Dr Huw Jones "Mankind has been engineering plant genomes since the move from hunter-gather lifestyles to farming-based communities. It is true that the one gene-one protein model is overly simple and that in specific cases, the situation is more complicated. For example, alternative splicing of exons from the same gene can generate different protein versions. Or different proteins can be generated from the same gene from RNA transcripts that overlap, or that originate from different reading frames or even in opposite orientations. However, these examples are understood and do not undermine the ability to reproducibly up- or down-regulate single genes to produce single proteins. This is the fundamental basis of the many biological research experiments in hundreds of Universities around the world to investigate exactly the point in your statement; gene function. I have absolutely no doubt that the constructions we inserted into our plants do not encode any other protein other that the ones intended."

Professor Julian Ma "I think it is fair to say that all molecules that are "foreign" to us are potentially biologically active compounds. And that we encounter many of these kinds of molecules everyday, in our food, the environment and from animals and other people. But you are right, some pharmaceuticals might be harmful if encountered inadvertently, we know that from the many toxic plants and micro-organisms in our environment."

"The use of GM plant biotechnology is not really different to other kinds of GM (in bacteria, yeast, mammalian cells, animals) that we currently use to make biotech medicines. But that is not to say that the risk management of these technologies does not have to be considered very carefully. Risk management is carried out on a product-to-product basis, the more highly you assess the risk of your target molecule, the more carefully you have to manage that risk. Many pharmaceuticals carry little risk, whilst others (as you point out) carry more. For the latter, the risk management strategy might be to increase the containment and isolation of your manufacturing. It would be possible to use plants that do not produce pollen or seed, or use plants (like moss or algae) that are grown entirely in containment."

"It's important to realise that GM plants for pharmceutical production does not refer to just one manufacturing platform. There are many options - different plant species, different levels of containment, production in different parts of a plant etc."

UK scientists have developed a new ‘super wheat’ variety and the early trials suggest that the new wheat is bigger and stronger than modern wheat varieties. If you could create a ‘super wheat’ what characteristics would it have?

We ran a live #plantsci Q&A with scientists working in this field, full text here.

Dr Joan Webber "Firstly, this figure of 90% of ash trees in Denmark have died from Chalara ash dieback is a mistake that has been promulgated widely in the press/media. Danish colleagues working in Chalara have made it clear that the correct version should be that 90% of ash in Denmark are affected, and not 90% dead. Affected doesn't mean that all trees will die and, in any event, the disease progress can be very slow in some trees and there are varying reports saying trees may take, 5, 8 or even 10 years before they succumb."

"It's much more difficult to answer the second part of the question - does this apply across Europe? All we can say is that many trees are affected across Europe, and the disease is now throughout most of the ash range in countries that have been affected for some years by the disease (eg Poland, Lithuania, Sweden, Norway and Denmark). So in those countries probably the majority of ash trees are affected by the disease and a high proportion, but not all, will have died as result of the disease either directly or indirectly. In the case of the latter, trees can be so weakened by the year on year effect of Chalara that they can succumb to other tree pathogens such as honey fungus (Armillaria) and these may be the final 'killing agents'."

"It's difficult to give exact figures because it would mean a huge survey effort to define the numbers of trees and then those affected/dead in all the various countries where ash is now affected by Chalara, so that's probably why there are no clear unambiguous figures for every country affected by Chalara."

Dr Timothy Marrs "Glyphosate cannot be linked to the neurological disorders listed. The toxicity of glyphosate has been extensively reviewed and is deemed safe to use by different organisations including the WHO (FAO/WHO, 1987; 2006). This herbicide has low or non-existent effects on how signals are transmitted in the brain. In addition to this glyphosate is poorly absorbed within our intestine, instead it is excreted unchanged in the urine. So not only does not affect how our brains work, there is also little chance of it entering our system if consumed, except in grose overdose."

"In addition to this there is no evidence of carcinogenic potential in longterm studies. There is little evidence to show that it damages the cell in a variety of in vitro and in vivo tests (FAO/WHO, 1987; Williams et al 2000; FAO/WHO (2006). Effects on fertility were not seen in multigeneration studies in the rat nor does it affect foetuses in utero."

"It is worth noting that the biochemical synthetic pathway that Roundup attacke in plants does not exist in humans."

References

Atkinson D. 1985. Toxicological properties of glyphosate, a summary. In: Grossbard E, Atkinson D, editors. The Herbicide Glyphosate. London: Butterworths 127-133.

FAO/WHO (1987). Pesticide residues in food - 1986. Evaluations 1986 Part II toxicology. FAO Plant production and protection paper 78/2. Rome. Food and Agriculture Organization of the United Nations. http://www.fao.org/docrep/W8141E/W8141E00.htm

FAO/WHO (1998). Pesticide residues in food - 1997. Report. FAO Plant Production and Protection Paper 145 . Rome. Food and Agriculture Organization of the United Nations. http://www.fao.org/docrep/W8141E/W8141E00.htm

FAO/WHO (2006). Pesticide residues in food - 1986. Evaluations 2004 Part II toxicology. Geneva. World Health Organization. http://whqlibdoc.who.int/publications/2006/9241665203_eng.pdf

Williams GM, Kroes R, Munro IC (2000). Safety evaluation and risk assessment of the herbicide Roundup and its active ingredient, glyphosate, for humans. Regul Toxicol Pharmacol;31:117-165.

Dr Astrid Wingler "Leaves normally contain green pigments (chlorophylls) and yellow pigments (carotenoids). In addition, red/purple pigments (anthocyanins) can contribute to leaf colour. Anthocyanins often accumulate during stress, especially in cold and sunny conditions, but also during the development of young leaves or during leaf senescence, e.g. in autumn. Some plants do, however, generally have high contents of anthocyanins, giving them a purple appearance, despite the presence of carotenoids and chlorophylls. By absorbing some of the light driving photosynthesis, anthocyanins can act as sunscreen, and it has been reported that leaves with high anthocyanin content therefore have lower rates of photosynthesis. On the other hand, anthocyanins can protect leaves, especially young and senescing leaves and evergreen species during winter. This protection may be due to the anti-oxidant activity of anthocyanins, but their exact function is controversial."

"Some ornamental shrubs appear “golden” because of a reduced content of chlorophyll and the presence of carotenoids. Photosynthesis could not occur without any chlorophyll, but to what extent photosynthesis is affected in “golden” leaves depends on the light conditions. Often, only leaves of the upper branches appear yellow, and more chlorophyll is synthesised in the shaded lower leaves, thus allowing sufficient absorption of light energy."

Dr Andrew Kiggundu "Are there any pros for Uganda investing in GMO golden banana? Yes, about 35% of Ugandan children are stunted, meaning that they will never archive their potential in life. Also 28% of Ugandan children and 52% women are vitamin A and zinc deficient. These deficiencies exist because most communities depend on staple starchy crops such as banana, cassava etc. In some western districts of Uganda even protein is hard to come by. Although there are fruits which grow abundantly in some places, they are only available seasonally twice a year."

"In order to prevent these deficiency problems crops are being developed with increased vitamin levels, also known as bio-fortification. The community will have the plantain materials free and can freely replant bananas as well as share them with their relatives and friends. With bio-fortified crops the government program to improve public health in rural communities can be easily realised."

"Cons… There are really no cons here except for the delays associated with regulation. We hope that the laws ensuring the biosafety of these crops will be in place soon."

Dr Jeremy Sweet "Pioneer Xianyu XY335 hybrid corn (maize) is not a GM maize, I have confirmed this with Pioneer. Where there appears to be confusion is that in China it is being used in the breeding of GM varieties because of its high yield potential. Similarly one of its parent lines PH4CV is also being used in the breeding of GM varieties as is shown in the patent reference in the Asia Times article. I am not aware whether these new GM varieties have entered the market in China and also how they are or will be marketed. Officially no GM maize is approved for marketing in China, but GM maize is being imported and controls are not very tight in some regions. Because of the high reputation of XY335 it is likely that similar/same names are being or will be used to market the new GM varieties. It is also note worthy that there is some duplication of "varieties" in China by some unscrupulous seed producers who are also selling material labelled as XY335 but of variable genetic origin."

*Further clarification

"Maize breeding is generally done by outcrossing to produce new lines, developing inbred lines of the best types with particular traits and then hybridising them to produce new hybrid commercial varieties with the required combinations of traits. This means that breeders maintain separate "pure" inbred lines which can be selected and used in breeding programmes. GM types are maintained as separate lines and are only introduced into hybrid varieties in the generation that produces the commercial hybrid seed. Thus the GM line is one parent of the commercial hybrid, the other parent being another non GM line with desirable traits. If combinations of GM events are required in a hybrid then a line is produced containing the combination of events which forms one parent of the hybrid. Alternatively two different GM lines may be used as parent lines to produce the commercial hybrid seed containing two (or more) GM events."

"In the case of Pioneer XY335 no GM line would have been used in the development of its parental lines as this would or could introduce GM into the hybrid."

"If GM is used in the breeding of any parental lines of varieties, including hybrids, then the resulting plants are classed as GM, even if the transgene is "absent" from the plant. This is because the transformation process may leave residual amounts of trangenic DNA in the plant or may induce unintended changes to the plant and these would have to be examined for biosafety."

Dr Sarah Al-Beidh "As you rightly mentioned, terpenes are key constituents of essential oils, responsible for much of the aroma/ flavour associated with a particular plant. Plants often produce these essential oils to confer antibacterial, antifungal, and/or insecticidal benefits."

"To develop different flavours, plant breeders utilise the natural variation that exists in populations. To do this, they cross seedlings, selecting individuals that display the most desirable traits. If this selective breeding focusses on flavour or aroma, the process is likely to influence the terpene profile of the resulting generations. The process is repeated over several generations, consistently selecting the ‘best’ individuals in the population (i.e. those exhibiting the most desirable traits). For reliability and consistency, it is important that these 'new' characteristics are shown to be genetically robust/ stable."

"As terpenes are temperatures sensitive, methodologies such as High Performance Liquid Chromatography (HPLC) and gas chromatography (GC) will be used to identify, separate and quantify terpenes in plants. The terpene profile of a sample plant will be compared against those of pure terpene standards. In your example of blackcurrant mint for example, a sample of this plant would have a terpene profile similar to that produced by blackcurrants (and of course, mint)."

Dr Ellen Colebrook "A plant is generally considered to be stressed if its growth, health or yield is compromised by factors such as disease or environmental conditions. To determine the level of stress a plant is experiencing, we usually measure some aspect of the plant’s physiology which changes in response to stress. One approach to monitoring plant stress in the field is by remote sensing. This involves using data collected from large areas by satellite or aircraft to analyse the light reflected from plant foliage. For example, thermal cameras (which detect infrared light) can be used to measure canopy temperature, which can be affected by stress. Another common way of measuring plant stress under field conditions is by testing the way in which light interacts with the green pigment chlorophyll in the leaf (chlorophyll fluorescence). This gives an indication of the efficiency of photosynthesis, which can be compromised by stress. A number of portable tools suitable for high-throughput use in field settings are available for this."

Dr Wendy Harwood "It is important to remember that herbicide tolerant crops can be bred by conventional means as well as using GM techniques. The development of herbicide tolerant weeds is an issue for all such crops. Good agricultural management can limit the development of resistant weeds. Where there has been extensive use of any single herbicide, including Roundup, and where agricultural practices to limit the development of resistant weeds have not been effectively employed, it is not surprising to see some herbicide tolerant weeds. This would be one possible risk considered in a full risk / benefit assessment that would be carried out before growing herbicide tolerant crops in new areas."

Insecticides, in particular neonicotinoids, and bees are being widely discussed. Articles appear regularly in the media, campaign groups ask people to sign petitions to protect bees, in parliament MPs are investigating insecticides and insects, in the EU they are considering a partial ban of neonicotinoids and some UK garden centres have already stopped their sale. But what are your questions? Some that we have already received include: What is causing the decline in bee health? Is bee colony collapse disorder linked to the presence of neonicitinoid pesticides? What safeguards are there that any alternatives to neonicotinoids that farmers may use will not have unforseen consequences?

We ran a live #plantsci Q&A with scientists working in this field, full text here.

Dr Eleanor Gilroy "The most time consuming stage of generating a GM crop is the years of fundamental plant science research that is required to gain the desired level of understanding of the plant characteristic to be modified."

"The transformation process itself, the means by which new DNA enters the plant cell nuclei, is relatively straightforward and takes a matter of days in the lab. The length of time it takes to physically make a transgenic plant from those transformed cells is roughly correlated with the length of the life cycle of any particular crop plant species. For example, the model plant Thale Cress (Arabidopsis thaliana) has a life cycle (seed to seed) of around 6 weeks which is why it is popular for scientists to use in the lab to study plant genetics. UK crops such as Barley and Potato would take 2-4 months to transform and generate seed. Tree-like crops such as apple or plum would take several years to reach a stage where they produce seeds."

"Developing an entire crop from a single transgenic plant however would take many generations to build up enough seed to plant a whole field or many fields, not to mention all the years of testing and legislation by food standards agencies before it could be considered a GM crop."

Dr Wendy Harwood "The key question is what testing is necessary to ensure that we can be confident of the safety of GM crops. Many scientists feel that GM crops have been subject to such extensive testing over the last 20 years that further animal testing is not scientifically justified. GM crops are currently assessed based on a comparative approach, looking to see if they are substantially the same as the equivalent non-GM crop. There has been 20 years of research using a range of techniques to compare GM crops to conventionally bred crops, looking for unintended changes in the GM crops. Such unintended changes have not been found (Herman & Price, 2012)."

"GM crops have been examined in feeding studies longer than 90 days. A review of 17 such studies is provided by Ricroch (2012). None of these studies found any new safety concerns and so did not add additional information to that obtained from 90-day feeding studies. 90-day feeding studies are the industry standard, it is important to remember that the life cycle of a mouse or rat is far shorter than that of humans. If extensive analysis of the composition of GM crops and 90-day feeding studies show no cause for concern, then longer feeding studies, with the associated delay to the approval process and extra costs, are not justified."

"Regarding the strain of rats used in the study by Séralini et al. and also for 90 day feeding studies, these were Sprague-Dawley rats. Sprague-Dawley rats are the standard lab rat for 90 day studies. They are not suitable for 2 year studies, because these rats only live an average of 2 years and are prone to spontaneous cancers. If these rats are fed a healthy balanced diet and kept for 2 years one might expect 40 to 75% to develop tumors making them unsuitable for long-term studies."

- Ricroch (2012), Assessment of GE food safety using ‘omics’ techniques and long-term animal feeding studies. New Biotechnology, dx.doi.org/10.1016/j.nbt.2012.12.001

- Herman & Price (2013) Unintended compositional changes in genetically modified (GM) crops: 20 years of research. J. Agric. Food Chem. dx.doi.org/10.1021/jf400135r

Sequencing and analysing the genomes of the ash dieback fungus and of ash will provide the information needed to help nature recover from the current epidemic. Scientists are pooling their expertise in collaborative research funded by BBSRC, announced on Friday 8th March.

The John Innes Centre ran a live Q&A about the research effort on Monday 11th March 12-1pm: http://oadb.tsl.ac.uk/?p=371

Professor Keith Lindsey "If you live in the UK, there is virtually no likelihood of GM pollen being present in your UK-produced honey, as there are no commercially grown GM crops planted out in this country. The small-scale research trials of potato and wheat do not produce significant amounts of pollen, and any pollen produced by such plants won't travel far because it is heavy, and the plants aren't bee-pollinated. Even if GM pollen did get into the food chain via honey, the genes present in commercially produced crops (outside the UK) are typically not expressed at high levels in pollen, and do not code for toxic or allergenic proteins - toxicity tests are carried out long before crop cultivation, as part of the very strict regulatory process. Remember that the genes present in GM crops are found in nature anyway, and you eat many of them all the time, with no deleterious consequences to your health."

Professor Martin Warren & Dr Sarah O’Connor "We are continually on the lookout for new plants. In addition to the secondary metabolites that plants make, we are also on the lookout for new crop plants with desirable traits. If we find a wheat plant that, for example, grows faster, is more disease resistant or is more drought tolerant, we can breed or "cross" that plant with the standard wheat plants used to generate a better crop. In fact, the wheat that we eat today looks very different from the wheat that we used hundreds of years ago! Scientists are also looking for the genes that control these desirable properties- if we know what the genes are, and where they are located on the plant genome, we will be able to do this selective breeding more quickly and effectively."

Professor Martin Warren "Genomics is discipline that analyses the structure and function of the genome and it is currently being used to gain a lot of knowledge through the comparison of genomes - which allows us to understand some of the larger scale phenotypic differences between plants. Through such comparisons we can learn how best to breed and/or engineer plants for useful traits and properties. Genetic modification (GM) is a technique rather than a discipline. The initial genetically modified plants and crops were contentious because the public was not fully engaged in the debate as to the usefulness of the approach. GM is being superseded by synthetic biology - but here there is full inclusion of social scientists to ensure that the subject is discussed in an open arena. The public perception is that genetic modification is not natural - but genomics tells us that nature has been shuffling large segments of DNA around for billions of years. So, getting back to the question, genomics tells us how and why plants are different and we can apply that information in a very targeted way to benefit agriculture - but this is likely to involve engineering of the genome. To try and disguise genetic engineering as genomics would likely cause more distrust. I would prefer to argue that genetic engineering is a natural process that can be harnessed for major agricultural and economic benefit."

Professor Alison Smith "Agricultural food production is facing an increasing number of challenges today in the face of increasing populations, climate changes, and reduction in fertile land. Ensuring security of food supply in the future - while at the same time avoiding further environmental problems and loss of natural habitats and species extinction - is going to be extremely difficult. We therefore need to use all the means we have to tackle the issues - not least because the problems differ around the world and for different agricultural products. In some cases it might be appropriate to modify agronomic practices to include havens for wildlife around field boundaries - as is encouraged for arable farmers in the UK today. In others, there may need to be more technological approaches such as modification of crop plants to withstand highly saline soils and/or particular pests and diseases. This latter approach may be conventional plant breeding - assuming that the desired trait is present in the gene pool for the plant - as well as GM to introduce novel traits."

Dr David Cooke "At the Ash Dieback workshop in London on 13th Dec two researchers from Denmark were present to share their experiences. During the coffee break I asked Lea Vig McKinney exactly this question. It is clear that the infection is airborne and there is no evidence for infection via the roots. The infection court is thought to be the leaves, leaf petioles or axils with the pathogen moving down the petiole into the twig and further into the stem from there. Girdling of shoots causes wilting symptoms. There are also some reports of infection at the base of the stem under high disease pressure. Surprisingly the infection phase of the life cycle has not been well studied. Much of the experimental work is based on wounding shoots and introducing the pathogen via these wounds."

Further information available at:

http://www.fraxback.eu/

http://forskning.ku.dk/search/profil/?id=203946

Plants can be modified to ‘grow’ medicines. For example, insulin can be ‘grown’ in a GM safflower plant, which would be cheaper and more efficient than current methods. These plant-made pharmaceuticals are never likely to enter the food-chain but they fall under the same EU regulations as GM crops that are grown as food. The EU GM regulatory system is lengthy and costly, making the cheaper plant-made alternative production method prohibitively expensive.

We ran a live #plantsci Q&A with scientists working in this field, full text here.

Dr Eleanor Gilroy "Yes you are right, genes are defined units of DNA and produce strings of RNA which are then translated into protein."

"So far no genes used in GM plants are predicted to make a protein that is dangerous to humans. Some GM crops have been developed to be dangerous to insects that eat them. Traditionally these plants would have been sprayed with a pesticide that would have killed a large number of non-target species along with the insects damaging the crops. Utilising GM means many more insects survive in the surrounding area allowing birds and other organisms to thrive better."

"GM crops and sprays are tested as vigorously as new drugs for their effect on us. After tests on their safety for human consumption more tests are performed on their impact on the environment by doing field trials. This is why it is so important that field trials are not destroyed. If they are, scientists have no way of measuring what the effect of growing GMs on the environment."

Dr Peter Eastmond "The answer to this question really depends on what biological process you want to study. Arabidopsis does most things your average plant does, and so for many biological questions it’s arguably the best experimental organism. However, it’s important to consider that there are also many things that Arabidopsis just doesn't do. For example its roots don't form symbiotic associations with mycorrhizal fungi or nitrogen-fixing bacteria like soybean for instance. Its leaves don’t employ C4-type photosynthesis like maize. Its seeds don’t contain a starchy endosperm like wheat or rice. And so on. To understand why Arabidopsis was adopted as a model organism and what advantages it holds over other plants, when it’s the appropriate tool for your question, then I recommend visiting the TAIR web site (http://www.arabidopsis.org/) and clicking on Arabidopsis thaliana. This is a route to a more comprehensive answer than I could hope to include here."

Professor Tim Benton "Yes, there is huge untapped variation in natural variation in crop species and this is important to local food security. However, the environment is also changing fast and GM is, at least in theory, a faster way of providing genetic variation than waiting for natural mutation and natural selection to maintain local productivity. Theoretically, there is nothing stopping drought resistant genes (for example) being designed in to a species and then it being bred into local varieties where they are particularly well locally adapted."

Professor Dave Goulson "The European Food Standards Agency recently reviewed the safety of neonicotinoid insecticides, and concluded that the three most widely used compounds, imidacloprid, clothianidin and thiamethoxam, pose an unacceptable risk when used on any crop visited by bees (e.g. oilseed rape, sunflower, maize). This decision is based on a number of recent scientific studies which demonstrate that the concentrations of neonicotinoids found in the pollen and nectar of treated crops are sufficient to have a range of impacts upon bees, including impaired ability to navigate and collect food, and reduced colony growth and reproduction in bumblebees. Concern has been heightened by recent evidence which suggests that neonicotinoids accumulate in soils and so are found in untreated follow-on crops, and that clouds of neonicotinoid dust are created during sowing of treated seeds which can kill bees and contaminate hedgerows. My personal opinion is that the EFSA stance is justified and sensible."

"However, it is important to realize that bees do also face many other threats, including a shortage of flowers in modern intensively farmed landscapes, and various parasites and diseases. Placing a moratorium on neonicotinoid use will not at one stroke solve all our bees’ problems."

Professor Huw Jones "The consumer can tell no difference but EU law requires food from GM crops to undergo a rigorous risk assessment before it can be imported or cultivated."

"Plants are the main source of food for Man and animals. Crop plants have been slowly improved, in one sense genetically modified, by farmers and plant breeders to give the highly efficient varieties we farm today. The early methods to develop new varieties were relatively passive, making simple crosses in the field. However, over the last century, plant breeding techniques have required more human intervention to provide useful genetic variation. Methods such as wide-crossing between species that would not hybridise in the wild, artificial mutagenesis to generate random changes in genes or marker assisted selection became increasingly used. Over the last thirty years, plant breeders have learned how to move single, specific genes form one organism to another by a method called ‘recombinant DNA technology’. Crops made by this method are what we know as GMOs and fall into EU legislation for testing and labelling. Many scientists see recombinant DNA technology as one more step (albeit an important one) in the continual development of ever better and predictable plant breeding methods."

Dr Alan Jones "Small trichromes (leaf hairs) exist in wheat and conventional plant breeders are working to enhance this. These hairs are advantageous for the wheat crop, as they reduce water consumption and increase resistance to pests. Special cultivars of wheat and other crops also have waxed (glaucous) leaves, which enhance drought resilience and reflect light. By implementing crops with features such as these globally, modelling analyses suggest a Global Warming reduction of -0.2˚C over 150 years. The only disadvantage might be that widespread changes to cropland reflectivity (and transpiration rates from changes to leaf morphology) would affect rainfall patterns in these agricultural regions."

Dr Jeremy Sweet "GM technologies being researched in developed countries can have useful applications in developing/poor countries. Examples are Bt maize, to control lepidopteran pests in Southern Africa, Vitamin A enriched rice and virus resistant GM papaya in SE Asia. Future examples are drought tolerance in maize and wheat which could have applications in many arid regions, and maize with herbicide tolerance for Stryga control in sub-Saharan Africa."

"Research being conducted in developed countries into plant genetics, molecular breeding and genetic modification techniques can be used to identify and transfer useful genes ( eg pest and disease resistance) to a range crop species of value in developing countries in order to improve the performance and stress tolerance of these crops. Thus for example, the gene mapping of rice, banana and sorghum can have worldwide implications for the breeding of these crops (see http://www.nuffieldbioethics.org/sites/default/files/GM%20Crops%20summary.pdf). Several UK (eg NIAB, JIC, Rothamsted) and other EU research organisations are studying GM crops for developing countries to address production and supply problems."

Professor Ottoline Leyser "We are some way from creating new species truly ex nihilo, but I think in the long term it will be possible. Perhaps more importantly, the ethical question you raise has been of relevance already for 100s of years. Through classical selective breeding we have created many organisms so different from those produced by natural selection that they can reasonably be classified as new species. Some of these were produced primarily for utilitarian reasons, but even for these, aesthetics has played an important part. For example maize is very different from its closest wild relative, and maize breeders over 1000s of years have selected aesthetic characteristics such as kernel colour, as well as more utilitarian ones, such as kernel size. For plants, most people are comfortable with the extremely unnatural forms we have created for our gardens. There is more controversy over similar extremes in animal breeding, where animal health is affected because, for example, we like our dachshunds long."

Professor Lars Ostergaard "During the transformation procedure to produce a GM plant, it is still necessary to include an antibiotic resistance marker gene, such as the gene that makes the cells resistant to Ampicillin. Although I can't comment on whether companies specifically use the Ampicillin-resistance gene in maize, I am certainly not aware of any studies that would show, that GM maize or any other GM plant product has had any ill-effects in costumers."

"What I can say is that the studies that have been done into gene transfer from the eaten plant material to bacteria in the gut have revealed that the risk of gene transfer is extremely small. Although, one can never exclude such possibilities in biology, it is less likely that pathogenic bacteria will acquire antibiotic resistance in this way compared to other ways."

"If you want to learn more, please see the following links and the references included. http://www.jic.ac.uk/corporate/about/publications/gm-debate/armg.htm"

Professor Rob Chilcott Based upon current evidence, the simple answer is probably no: a diet based entirely on organically-grown produce would be unlikely to affect sperm levels.

There are a number of scientific studies which indicate that some pesticides may have “anti-androgenic” activity: an effect which interferes with the normal response of the body to male hormones. The actual quantity of such pesticides in the food we eat is subject to very strict controls and so it is unlikely that the concentration of any one pesticide would be sufficient to cause a measureable effect. In saying that, the effects of some pesticides may be additive. That is, exposure to a number of substances (at a low dose) may result in an overall dose which may be sufficient to cause an effect. However, no studies in humans have established a link between pesticide residues and male infertility.

It is worth considering that we are exposed on a daily basis to a wide variety of chemicals present in our diet and environment which may potentially affect fertility. So, sticking to organic food would probably not make much difference to our total daily intake. It is also worth pointing out that whilst organic foods may generally contain less pesticide residues, it doesn’t necessarily eliminate exposure. The type and amounts of pesticides used on all crops are subject to strict controls which are monitored and enforced by the UK’s Food Standards Agency (FSA).

Dr Sarah Al-Beidh "A few factors need to be considered to help answer this. First, tree species vary in their 'nutrient use efficiency' (NUE) which relates to how effectively they are able to utilise nutrients. A tree's response(s) to nutrient application can therefore vary depending on the species considered. Second, environmental conditions can influence the responses of trees to fertiliser application. Research conducted on Eucalyptus trees in Australia for example, found that N& P fertiliser applied in dry weather (low soil moisture) detrimentally affected pulp yield, wood fibre length and wood density- responses not observed when soil moisture was (near) optimal. Third, what we mean by 'quality timber' is likely to depend on the end product of the wood; one reason Stradivarius violins are considered the best quality in the world is that low ambient temperatures and slow, constant growth rates produced trees with uniform growth rings and (therefore) consistent timber density. Finally consider tree age and site quality; the effects of fertiliser application are likely to be reduced in older vs. younger trees and in trees growing in soil with high nutrient availability compared to those in nutrient-poor sites."

"In principle, responsible fertiliser application in optimal environmental conditions is unlikely to be detrimental; however, it is likely to affect tree volume and in doing so may affect timber quality. Whether this effect is considered detrimental or beneficial is likely to depend on how timber quality is defined."

Dr Ellen Colebrook "Agriculture is a contributor to climate change through many routes, for example through the use of fertilisers (which results in greenhouse gas emissions). Any changes in practice or new technologies which improve the efficiency of, or reduce the need for, inputs such as fertilisers, herbicides and insecticides have the potential to reduce emissions. The production of crops that grow better with lower inputs, including by genetic modification, could contribute to this. Also, the growing of non-food crops as renewable sources of energy and transport fuel could off-set the emissions produced by fossil fuels and lock more carbon in the soil, helping to combat climate change. It’s possible that GM could speed up the improvement of these crops."

Professor Maurice Moloney "1) The approximate breakdown (unaudited!) is as follows:
~60% from BBSRC in the form of Institute Strategic Program Grants and competitive responsive mode grants
~10% from other Exchequer sources including DEFRA, DECC, DIfD, NERC
~7% EU
~4% Foundations such as The Lawes Agricultural Trust, Bill and Melinda Gates, Perry Foundation, Felix Cobbold etc
~12% Industrial research collaborations
~5% Levy boards and crop research agencies (HGCA, BBRO, AHDB etc)
~2% royalties, licence fees etc"

"2) Yes, but not (as far as I know) in the more extreme end of the spectrum such as GM-freeze etc. Typically, we have staff who are members of RSPB, Butterfly Conservation, Wildlife Trust, FoE, CPRE etc. However, staff are not required to divulge involvement in any NGO or political organisation."

"3) Funding from BBSRC and other research councils is for work covered in their strategic plans (e.g. http://www.bbsrc.ac.uk/nmsruntime/saveasdialog.aspx?lID=3719&sID=6953 ) and therefore the funding sources do play a role in determining which areas are studied. However, the funding bodies, including industry, have no say in how a Rothamsted scientist interprets her/his own results. The principles of academic freedom apply in Institutes just as they do in Universities."

Dr Astrid Wingler "Roots can take up nutrients directly from the soil. In nature, however, most plant species form symbioses with mycorrhizal fungi which, through their extensive mycelium, increase nutrient uptake, thereby improving the supply of nutrients to the roots."

"Like other plant cells, root cells are enclosed by a membrane, which in turn is surrounded by a cell wall. While the cell wall is permeable to water and most nutrients, specific transport proteins are required to take up nutrients, such as nitrate, phosphate or potassium, into the root cells. Water and nutrients are transported from the roots to the shoots in a system called xylem. On their way from the soil into the xylem nutrients have to cross cell membranes at least twice: (i) to get into the centre of the root which is sealed off by a hydrophobic strip that prevents transport through the cell wall; (ii) to be loaded into the xylem."

"Nanoparticles can, in theory, follow the same route, but they can also enter the roots through wounding. Whether or not they are taken up and transported to the shoots depends on e.g. their size, surface charge and also the plant species. There is concern that nanoparticles taken up by plants may be toxic to the plants themselves or accumulate in the food chain. On the other hand, it may be possible to use nanoparticles for the delivery of fertilisers, herbicides or pesticides."

Dr Alan Jones Much of the flora of North America may have become extinct. However, plant life is generally resilient to mass extinction events, owing to long-lived seeds and underground rhizomes. It is likely that over millions of years, the global genetic diversity of plants was able to fully recover from this event. The most photosynthetically efficient plants ever to exist are the C4 plants, which evolved carbon concentrating mechanisms around 25 million years ago; some 40 million years after the K-T mass extinction event. At times in the Earth's history when CO2 levels were lower than present, plants evolved more stomata to cope. This adaptation is not an advantage under present conditions, because it increases water use (i.e. droughting).

Professor Tim Benton "With new technologies, which are truly untried, the precautionary principle indicates that one should be very cautious about deployment. However, as technologies get adopted and if risks are not realised the need for precaution falls. GM crops have been around for decades now, and are grown, globally, over about 10% of the cropped area by millions of farmers big and small. They also increase farm-gate incomes (when taking out the seed-provider premium) by about USD78bn per year. Both these suggest the caution with which the EU has approached GM is not needed and the costs of not using GM are increasing (in terms of lost revenue and lost R&D); and both are being recognised in Europe. Indeed, in a recent report by the Commission concludes (p16) “The main conclusion to be drawn from the efforts of more than 130 research projects, covering a period of more than 25 years of research, and involving more than 500 independent research groups, is that biotechnology, and in particular GMOs, are not per se more risky than e.g. conventional plant breeding technologies.” (http://www.plantsci.org.uk/sites/default/files/a-decade-of-eu-funded-gmo-research_en.pdf)."

Professor Maurice Moloney "In a general sense, the fact that Monsanto has a patent on a new gene does not interfere with the work of a conventional plant breeder. The patent system does not allow a patent of something that occurs naturally. The Company must have "improved" it in some way outside the plant. This means that a 'naturally occurring' plant gene cannot be blocked by a Company. Sometimes, the combination of the Company "improved gene" and the variety that the plant breeder has developed is seen to be a beneficial combination. If that is the case, the breeder and the Company have to negotiate a deal. Generally, the breeders have done quite well in those negotiations (see Pioneer Hybred, Limagrain, KWS and SES van der Have). This is because (and most people don't know this) plant breeders also have protection called Plant Breeders rights under the international Plant Variety Protection system (PVP, http://en.wikipedia.org/wiki/Plant_Variety_Protection_Act_of_1970). This provides for 20 year protection for the plant breeder for their registered varieties. Overall, the system is well-balanced and plant breeding companies have done just as well as the big companies like Monsanto. Without a plant breeder, none of the companies have access to the market really."

Professor Dave Goulson "Neonicotinoids have been in use since ~1994, and their use has increased greatly over time. They are not uniquely harmful to bees; more or less all known insecticides are inevitably toxic to bees. Neonicotinoids are predominantly used as a seed dressing; they are systemic, spreading through the plant tissues and entering the nectar and pollen of treated crops such as oilseed rape. They are quite persistent chemicals, remaining in the plant for months and in the soil for years. In contrast, non-systemic alternatives such as pyrethroid insecticides which are typically sprayed on the crop are short-lived in the environment, breaking down within a few days, so as long as they are not sprayed on flowering crops they pose little threat to bees."

Dr Astrid Wingler "In contrast to animals, which need to burn organic compounds in respiration for energy supply, green plants can convert light energy into chemical energy in the form of ATP in the process of photosynthesis. However, plants cells also contain mitochondria, the organelles in which respiration takes place. Respiration is required in the non-green organs of the plant (e.g. roots), but also happens in green organs, such as the leaves. While 24-hour days are unlikely to directly affect rates of respiration in non-green organs (especially if they are underground), it is widely assumed that light suppresses respiration in leaves. This is, however, not trivial to analyse: in the light the rates of carbon dioxide and oxygen exchange between leaves and the atmosphere are not only resulting from respiration, but also (and more strongly so) from photosynthesis and another process called photorespiration. Nevertheless, sophisticated measurements show that respiration does happen in the leaves in the light, even if the rates are reduced. To what extent respiration in green organs is required for plant growth is another interesting question."

Professor Huw Jones and Professor Patrick du Jardin "No. The natural plant virus, the Cauliflower mosaic virus, is ubiquitous in plants and derived foods, both GM and non-GM and does not pose safety concerns to human and animal health."

Dr Smita Kurup "Yes, peppermint is a hybrid of Mentha spicata and Mentha aquatica. Seeds of peppermint are set from this cross, however peppermint (Mentha piperita) is sterile so the hybrid plant will not set seed. It's not normal to find peppermint seed unless the cultivator has crossed the two required species, even then, the essential oils can vary between crosses. I think a lot of the time, M. spicata (spearmint) is sold as peppermint. I would suggest being cautious about any seed sold as peppermint. I think its best to buy the plant and propagate vegetatively (by rhizome)."

Professor Ottoline Leyser "Even in the UK where farming methods are well developed and yields are already high, I think sustainable intensification is achievable, especially if you consider the whole food production system from farm to fork. Improvements to reduce inputs while stably increasing outputs can be made right across the system. These include research-driven improvements to crop management and crop varieties both in the field and post-harvest, reducing waste throughout and reducing meat consumption. What are the chances of these improvements being realised? Unfortunately, I think progress is likely to be reactive rather than proactive, driven by continued increases food prices and instability in food supply."

Dr Cornelia Eisenach "In the ‘dark’, blue light would make the light-dependent photosynthetic reactions work, albeit at lower efficiency. However, the ‘products’ of the photochemical work are used in a complex metabolic pathway, called the Calvin-Benson Cycle. Some of the enzymes of this cycle are ‘activated’ by light, so the cycle, in effect, does not work in the dark. The ferredoxin/thioredoxin system is responsible for the light-dependence of Calvin-Benson Cycle enzyme activity. I don’t know exactly the action spectrum of the ferredoxin/thioredoxin system, i.e. whether it would still be able to ‘activate’ enzymes under blue light, or whether it has even been tested."

Professor Keith Lindsey Companies hoping to introduce new GM crops onto the market in Europehave to submit a very large dossier of relevant evidence, which includes data on the molecular characterization of the introduced genes, their safety in terms of toxicological studies, effects on the plant, and effects on the environment. Some of these data are published in the peer-reviewed scientific literature, for all to scrutinize. The dossier is assessed in Europe by expert panels, that include in the UK for example molecular biologists, ecologists, agronomists and farmers. The advice produced by the regulatory panel (known in the UK as the Advisory Committee on Releases to the Environment, ACRE) is published on its public website (http://www.defra.gov.uk/acre/) and informs government ministers, who then consider the advice and make a decision on whether to support the application from the company at European level, prior to further action. Sothere is a large body of scientific evidence on various types of GM maize and soya available to the public, which is considered in relation to determining whether there is a significant risk to human health and the environment.

Dr Anne Osterrieder "Plant cells synthesise compounds in a chain of chemical processes, also known as metabolic pathways. In each step an enzyme makes changes to a precursor, just like a machine in a factory, and passes them on to the next enzyme until the precursor has been turned into the end product. If you externally supplied nutrients or precursors, you would first need to make sure that all cells take them up. Then the cell would need to include the additional compounds into its existing pathway. Production of more end products would depend on a number of things, such as the availability of free enzyme molecules or the ability of the cell to make more enzymes on demand. I think the answer to this is: ‘It depends!’"

Dr Peter Eastmond "If the daisies are the common English species Bellis perennis then they would usually flower in early to midsummer. However, they are also known to flower in mild winters and it's most probable that the recent mild weather is the cause."

Dr Sarah Al Beidh "The short answer is – they're big because they can be! Bananas grow predominantly in wet tropical lowlands where the growing conditions are more favourable than temperate regions. Adequate natural soils, no shortage of water, along with warm weather and almost 12 hours of daylight throughout the year enable banana trees to grow quickly and have large leaves. As you rightly mentioned, for plants growing in the shady understory of a forest, large leaves also capture as much of the available light as possible and so can make the maximum amount of ‘food’ through photosynthesis. In comparison, plants in temperate regions have to endure freezing temperatures so have developed strategies to cope. These include shedding their leaves in winter (e.g. deciduous trees) or reducing them to tough needle-like structures filled with natural ‘anti-freeze’ (e.g. pines in northern forests)."

Professor Alison Smith "Some studies have shown that the nutrient content of today's fruit and vegetables are lower than those measured in the past. In the case of apples, one explanation is that the newer varieties have been bred for yield and appearance, with little attention paid to the nutrient content. However these varieties have all been established by conventional plant breeding - that is crossing two varieties together and then selecting different traits from amongst the offspring. As far as I know there are no GM apples. In fact the first major GM crop, and the one that was sold in the UK in the 1990s, was GM tomatoes - called Flavr Savr. These were modified so that during ripening, although the fruits turned red, and became sweeter as the acid was turned to sugar, they did not soften very much. This gave them a longer time to sweeten, and also facilitated processing. I think that in the UK all the fruit was used for making tomato puree. Analysis of the nutrient content - vitamin A, vitamin C, vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin) and vitamin B6 (pyridoxal), as well as elements such as Ca - showed no difference compared to non-GM fruit."

Dr Sarah Al-Beidh "In recent years, there have been a number of new pests and diseases recorded in Britain. Most of these however, have come here as a result of the international trade in plants and plant products, rather than climate change. Global warming does have the potential to affect many types of plants- not just deciduous trees. Some plants will benefit from a warmer and wetter climate while others may be adversely affected. Where climate change is gradual, plants are able to adapt; however, rapid climate change puts plants under stress and this may cause some plants to decline in areas where the climate is no longer suitable. Stressed plants may become more vulnerable to pest and diseases."

Dr Hanna Tuomisto "‘Food forest’ or forest gardening is a form of agroforestry where food crops and trees are planted together. In a forest garden food plants can be grown in many layers, including fruit trees, nut trees, berry bushes, vegetables, herbs, mushrooms, root vegetables and vines. A well designed forest garden can be nearly self-maintaining. More information about forest gardening and other types of agroforestry can be found on www.agroforestry.co.uk."

Dr Alan Jones "White flowers suggest this species is pollinated by night-flying moths, which are the most visible flowers at night, particularly during full-moon nights. This species produces large, highly fragranced (and, therefore, highly attractive) flowers. By minimising the time spent investing in this organ, and being synchronous with other members of the species, this plant minimises the total 'cost' of reproduction and maximises its chance of reproductive success. This is essentially the basis of natural selection. Selenicereus grandiflorus, maximises pollination potential by putting all its 'eggs in one basket' in one night, monopolising pollinator activity for several hours - by sheer force of numbers. This strategy will go wrong if the timing coincides with adverse weather conditions."

Dr Astrid Wingler "Over half of the nitrogen added to the soil as fertiliser is lost, e.g. by leaching of nitrates or production of the greenhouse gas N2O. Fertiliser input into agricultural systems could be reduced by engineering crops, such cereals, to form symbioses with N2-fixing bacteria or by introducing the N2-fixing enzyme nitrogenase directly into plants. The higher input of nitrogen could theoretically result in increased leaching of e.g. nitrates. However, since the nitrogen would be fixed within the plants and therefore be directly available for growth, the amount leached would probably be much less than for fertiliser applied to the soil."

Dr Sarah Al-Beidhe "When it comes to applying biochar to soil, more horticulturally-focused research in temperate systems is needed as we still have questions on its long-term effect(s) on soil health. Also not all biochar is the same - different raw materials and production processes result in biochar with different chemical and physical properties. Even fewer studies have investigated the impact of biochar on soil fauna so, whilst it’s unlikely that it has any adverse effects on soil-dwelling invertebrates, more research is definitely needed! The physical structure of a clay soil can be considerably improved by digging a 10cm layer of bulky organic matter (such as mature garden compost) into each 30cm of soil."

Professor Rob Chilcot "Our digestive tract has evolved to produce a wide range of enzymes which are very effective at breaking down our food into small molecules to allow absorption into our body. The same goes for the DNA within our food: it is extensively digested into its component molecules before being absorbed. Therefore, we do not actually absorb the genes present within our food (whether genetically modified or not), but we do absorb the molecules the genes were originally built from. The molecules we absorb from our digestive tract can then be used by our bodies to produce, amongst other things, new (human) DNA. Some people have argued that we do absorb genes from our food and that these can be inserted into our genome. If that were true then we would all be carrying genes from everything we had ever eaten: the human race would probably have died out millennia ago or we would currently be evolving into our favourite meals."

Paul Temple "Low yield is a problem for one very simple reason, there are more people every year to feed and we haven't more land in which to carry out expansive farming low output agriculture. Taking the UK as a example. The recent census revealed an additional two million people now live and need food in the UK. As a net importing nation we therefore require yet more land in other countries to service demand. Producing less food simply adds tension to an already rising food market and while the wealthier part of the population can cope it creates real problems for the poorest."

Dr Wendy Harwood "Genetically modified crops are already widely grown; on over 395 million acres worldwide last year. If this area was expanded further the issue of whether ecosystems would gain or lose would depend entirely on what sort of crop was grown and where. It has to be remembered that GM is just a technology and it is the particular introduced trait that is important rather than the technology used to develop the crop. Some traits could impact the environment negatively and some positively."

Dr Hanna Tuomisto "A recent study suggests that urban noise may be a key cause of declining sparrow populations. Changes in agricultural practices play a role too. Farmers can help sparrows by providing feeding and nesting habitats, such as non-cropped areas, wild flower plantations and over-winter stubbles."

Paul Temple "It is possible to farm organically without livestock. However it makes more sense and improves the fertility build up required in an organic system to use livestock through grazing, feeding green crops, utilising straw and returning manure. Organic crop output is significantly lower than conventional routes, using livestock improves overall food output in the cycle, offering the chance to improve soil fertility and organic matter."

Professor Keith Goulding (guest contributor) "As a scientific community, Rothamsted Research does not seek to ‘take on’ anyone but works with farmers and all those who have an interest in good soil management. Organisations such as ours work with LEAF (Linking Environment And Farming) and its collaborators such as Waitrose and ASDA, directly with M&S and Sainsbury’s, and with multinationals such as BASF, to translate our research on soils into practice. Current projects are exploring the role of organic matter in stimulating earthworms and good soil structure, how plants can be used to manage soils, and what simple measures of soil biodiversity can be used as indicators of soil health. The challenge for all of us in a global market is to work with farmers to help them manage their soils well while producing food at a price that people can and will pay. Rothamsted and others who have a commitment to soil health, are members of the Global Soil Biodiversity Initiative: http://www.globalsoilbiodiversity.org/?q=participants "

Questions were answered on the environmental impact of organic and conventional farming on the land used.
• Is organic farming better for local wildlife?
• If we want to increase yields doesn’t that mean we have to use a lot more pesticides?
• We waste so much food; do we really need to grow more?

We ran a live #plantsci Q&A with scientists working in this field, full text here: http://www.senseaboutscience.org/pages/-environmental-impact-of-conventional-and-organic-farming-on-the-land-used-480.html

Questions were answered on GM trials, super-weeds, and ecosystems.

We ran a live #plantsci Q&A with scientists working in this field, full text here: http://www.senseaboutscience.org/pages/-safety-and-regulation-of-gm-478.html

Questions were answered about the interplay between genes from GM and wild species, the identity of a species after multiple modifications, and testing of GM crops.

We ran a live #plantsci Q&A with Professor Jones about these issues, full text here: http://www.senseaboutscience.org/pages/-genes-and-testing-of-gm-crops-476.html

Questions were answered about putting animal genes into crops to increase protein content, and risk of increased incidence of allergic reactions due to novel proteins.

We ran a live #plantsci Q&A with Dr Aradottir about these issues, full text here: http://www.senseaboutscience.org/pages/-consumption-of-gm-crops-474.html

Questions were asked about 'super-weeds' and GM crops - what they are, their impact on the ecosystem, and what we know about their safety.

We ran a live #plantsci Q&A with scientists working in this field, full text here: http://www.senseaboutscience.org/pages/-gm-trials-super-weeds-and-ecosystems-472.html

Questions about GM crop patenting and ownership, and the ethics of GM research were answered by Professor Maurice Moloney, Director and Chief Executive of Rothamsted Research, and Professor Jonathan Jones, Senior Scientist at the Sainsbury Laboratory.

The questions and answers from this live #plantsci Q&A can be seen here: http://www.senseaboutscience.org/pages/-commercialisation-of-gm-470.html

Experts on GM cereal crops answered questions about the spread of wheat pollen, 'jumping genes', and other risks and benefits of GM wheat crops.

All the questions and answers from this live #plantsci Q&A can be found here: http://www.senseaboutscience.org/pages/-cross-pollination-468.html