Sense about Science ? equipping people to make sense of science and evidence
What would your ideal ‘super wheat’ be?
Live online Q&A
On Wednesday 22nd May wheat researchers, Dr Phil Howell, Dr Robert Koebner and Professor Mike Bevan discussed people's suggested traits; whether it could be bred into wheat and how it could be done. Meet our panel here. An event held by Sense About Science for Fascination of Plants Day.
23. How about wheat fields where you could simultaneously grow another (winter) root crop underground? (@SAPS_News)
PH: "For this to work you’d need to plant the root crop first, before drilling the wheat, and harvest it last, after the combine has taken all the grain. It would need to be a crop that puts on most of its growth before the wheat crop outcompetes it. It would cause problems at wheat harvest time if the root crop still had green leaves above the ground, as these will jam up the combine which is designed to operate on dry physiologically mature crops. At NIAB, our agronomists are looking at undersowing the wheat crop with a N-fixing cover crop like clover, which can fix some nitrogen before the wheat outcompetes it."
22. Wheat to suit grazing by animals pre-flowering? (@RoseGWhite)
PH: "In parts of the US, wheat is grown as a pasture crop. Wheat can be grazed pre-flowering and I always give my seedlings a gentle trim when they come out of the cold room before potting up, this helps the light reach the base of the plant (preventing against lodging later on), promotes tillering (the growth of side shoots) and puts a brake on “soft” lush growth that just sits there, gets mildew, and stops water reaching the roots. Getting the balance right is the difficult part – grazing animals don’t always know when to stop (rabbits!) and if the crop is grazed too hard or too late it can hold development back and really impact on yield. Plus grazing animals can cause compaction problems to the soil structure."
21. Can we create wheat that will thrive in wetter weather without much sun? (Mike Fife)
MB: "Good question. Wheat grows optimally in temperate climates- not too hot, not too cold, not too wet, not too dry. Any big variation from these optimal conditions lowers yield. We would have to approach the two problems you raise separately because each is a different physiological response. About sunlight, there is only a little that can be done because growth and grain production require energy from the sun. Bigger leaves angled to collect available light could increase yields. About water-logging more could be done to increase root health in wet soils, but I don't know how. To help in flooded conditions there is a gene used in rice to promote stem growth when the plant is submerged in the paddy field.
One of the biggest threats to crops growing in these conditions is diseases, particularly fungal pests. A lot is known about how plants mount defences against pathogens and this knowledge can be used to create in-built protection. This requires GM solutions but some consumers are not in favour of this approach. I think it will be essential to use this approach to stop crop wastage and increase the sustainability of food production."
PH: "If we get more years like the last 12 months, we will inevitably shift towards varieties that do better in dull wet conditions. We have to split this into two areas though. Firstly, the wet: this can cause problems with waterlogging (starving the roots of oxygen) leaching (washing the nutrients out of the soil) and most damagingly, change the soil structure making it a physically demanding environment for anything to grow in. It will take farmers a long time to repair the damage to their soils from the year we’ve just come through. Then there are diseases like septoria tritici blotch which thrive in wet conditions and fusarium head blight which was rampant last year because of damp weather at flowering time. If it’s raining, farmers can’t spray. If the ground is saturated, farmers can’t even travel across it even if the sun is shining. Then poor weather at harvest can cause problems with crop losses because of lodging and pre-harvest sprouting, and increased costs as the grain must be dried down before it can be safely stored without spoiling.
Then the lack of sunshine – obviously you need light for photosynthesis and one reason yields were so depressing last year was the lack of sunshine. Dull conditions at flowering can also cause sterility problems so the wheat ears contain “blind sites” where there are empty spaces instead of grains. Best yields come from cool, bright conditions from flowering onwards."
20. How bespoke can you make a "super wheat"? Could you design one with the capacity – built in – for it to change and adapt to a farmers' conditions over a number of years/decades? (Dominic Berry)
RK: "One can certainly adapt wheat to particular environmental conditions, after all, the crop is grown on every continent (even at the Equator, though admittedly at high altitudes). But the idea of building in the flexibility to adapt to changing conditions is problematic, since the genes present in a particular variety are fixed for that variety. Breeders tend to develop varieties which do well in a variety of environments (maybe not the very best in any of these environments) which gives some sort of assurance that they will be able to cope with the expected year to year variation in the climate. Bear in mind though that it takes about 10 years to go from a cross to a finished variety; that's a big investment in time, so it's not possible to fit every possible combination of climate/soil/ etc."
19. What about wheat that provides extra vitamins, in a similar way to golden rice? (@RebeccaNesbit)
RK: "Just as golden rice has been engineered to make more Vitamin A, so wheat could be too. The reason for doing that work in rice was the large numbers of people for whom rice was a major component of their diet, and lacked a good source of vitamin A. Does that apply for consumers of wheat? Are there significant numbers of people who rely very heavily on wheat for sustenance? Before launching a project to engineer wheat (or any crop for that matter) to produce more of vitamin XXX, you would need to be sure that it would serve a useful purpose."
PH: "There is variation in carotenoid content in the wheat grain and a leading breadmaking variety often drew criticism from millers because it produced a loaf with a more golden crumb – consumers wanted white bread not yellow bread!
The bran and germ components of wholegrains are where most of the vitamins are found, so a switch to more wholegrain products is a good start. In other grains like barley there are some mutants which have large embryos, so the whole grain products have a different nutritional profile to conventional barley whole grains. So, there is variation (in nutritional content) there, it’s a case of finding it, understanding it, making sure it works (the 3 x copies of gene problem again), and then making sure it’s something people still want to eat."
18. "Ideally, would superwheat be able to fix N via symbiotic relationships with soil dwelling organisms? (@mattaudley)
"What about a "super-wheat" with increased nitrogen uptake?" (@olenyi)
PH: "We had some promising results from trials at Rothamsted and University of Nottingham which might point towards this material being better at nitrogen uptake. But we need to repeat the work over seasons and locations to check how robust this is. Nitrogen fixation would be great. JIC have just started a big programme of work to investigate this. However, turning atmospheric nitrogen into nitrate uses a lot of energy, whether done by bacteria or the Haber process, so we might end up with nitrogen-fixing wheat that only yields as much as peas!"
17. "Can you get fire resistant wheat? Increased temperatures, increased fire events with predicted climate change? (@Chr1s_Peters)
MB: "This is not possible as all living material can be easily burnt. What you can do is to reduce the chances of fire in the growing environment, as is done for forests world-wide with fire breaks and early detection. Climate change is predicted to have a big effect on crops by changing the environment that crops are adapted to grow in - this is the biggest risk. Scientists are working to understand how crops respond to seasons and temperature fluctuations and then identify lines that might be better adapted. For example, the time of year plants flower is very dependent on the cold they sense in the winter and the warming days of spring."
16. "Robust deep rooting system to cope with water logging. Robust stalks redesign seed architecture downwards. In other words cross with Scottish oats which cope better with Scottish weather?" (@RuralLeader)
PH: "Crossing Scottish oats with any wheat won’t work I’m afraid! The crops are too distantly related to cross together. Wheat roots remain a big target for improvement, partly because they are so difficult to get to and measure. There are several projects which are ongoing at the moment looking at wheat root development, aiming to increase rooting at depth in order to improve water uptake and nutrient uptake. Plus wheat has structural roots too which help to anchor the crop in the ground and prevent lodging (where the crop falls over) – stiff strawed varieties can lodge from the very base if they don’t have this strong foundation of structural roots."
15. "Could we breed "super wheat" with root exudates that inhibit black grass germination?" (@EwenMcEwen)
MB: "This is a very long shot, as black grass is very closely related to wheat. So anything made by wheat affecting black grass seeds/seedlings will probably affect the wheat crop as well. My solution, which is very feasible and has other benefits, would be to make the wheat crop tolerant to herbicides that kill black grass. When black grass emerges in the field along with other weeds, it can be killed directly and the wheat will grow happily. The other advantages of this approach include reduced tillage of the field between crop plantings so more organic matter can build up and less energy is used for growing the crop. Such herbicide tolerant crops are widely used and do not harm human health or the environment. The herbicides are widely used except in organic production."
14. "Wheat with radically different leaves in early and late growth stages, maximising interception early and radiation use efficiency late (how well you can turn light into yield)?" (@standardbrit)
PH: "Modern UK varieties already have a different canopy to older varieties, with quite erect leaves that allow light to penetrate deeper into the canopy rather than floppy upper leaves which shade the lower leaves. I like the idea of leafy early growth, which can smother competing weeds and build nice strong plants with vigorous root systems, but then switching across to the more erect-leaf model we currently have as the plant wakes up during the spring and stem extension commences. A new ideotype for crop physiologists to work on perhaps."
13. How does the new "super wheat" respond to biotic and abiotic stresses? (@egilro)
PH: "Firstly there’s not just one “super wheat” (BBC’s term, not ours), we’re still testing hundreds of possible ones to try and identify the best. Biotic stresses? We’re testing against diseases in inoculated nurseries this year. Abiotic? Well the ones that did well are pretty tolerant of waterlogging!! The original work by CIMMYT (the international maize and wheat improvement centre) on their synthetic hexaploid wheats – which these were bred from – suggests they can be pretty robust, especially against heat and drought stress."
12. "Could straw quality and composition be changed to improve its end use, either as a feed for animals eg by improving its texture and nutritional quality, or its industial use as a material or fuel?" (Jeremy Sweet)
PH: Yes it can, provided that there are sources of variation out there. Traditionally wheat straw is used for animal bedding but barley straw can be fed, which suggests there is plenty of variation out there. If we find the right straw characters in old varieties, or land races (locally-adapted “farmer varieties”), or even closely related cereals, we can transfer this into wheat just by traditional crossing and selection. Casting further afield we would need to use tissue culture techniques like protoplast fusion. Further afield still and we might need a GM approach. Ultimately though straw is still seen as something of a by-product – we need a high-value use for it to justify investment in more research and breeding.
RK: "In principle one could target straw quality (and certainly its quantity) by either conventional breeding or genetic engineering. Most wheats have hollow straw, but a few have pith-filled straw (I have no idea whether animals would prefer this). The economics of using straw as animal feed is another matter. The same economic issue applies to industrial uses of straw. (Farmers in the past used to burn it in situ as it was considered to be a waste product with no market.) Upping the quantity of straw would have implications on the grain yield (see earlier question re short-stemmed wheats)."
11. "I'd like to see whole-wheat that didn't set off my IBS. Whole-wheat currently has too much fructan type fiber, but oats have a different fiber and are fine for IBS." (Olive)
PH: "Some grains are better than others for people with specific dietary requirements. Modifications to nutrional aspects are tricky in wheat because it’s a hexaploid – it has 3 complete sets of chromosomes - so typically you need to change 3 genes to make a difference rather than just one. There are groups looking at these problems around the world but progress is quite slow. Often you need to use mutations where one of the key genes has been altered, and then cross the different mutations together for each of the three sets of chromosomes, and then make sure everything is in the right genetic background. Slow and steady work, but hastened by modern marker-assisted breeding techniques."
10. "Wheat with quick maturation?" (@halften)
RK: "Fast maturing wheats are really important where the climate limits the length of the growing period. In India, it quickly gets too hot for wheat to able to grow, so Indian wheats are bred to mature very much faster than UK ones do. In general, the longer the growing period, the higher the yield, which is why most of UK wheat is sown in the autumn and harvested at the end of the next summer. If our climate becomes hotter and/or drier, our wheats will have to be quicker maturers. There's plenty of natural variation for this trait for breeders to work on."
MB: "Good question. Current wheat varieties grown in the UK are very finely tuned to respond as rapidly as possible to their growing environment such that grain development can use the full length of the summer to harvest the energy of the sun. Wheat varieties are autumn or spring sown. Spring sown wheats respond very quickly to the lengthening days and increasing temperatures of the spring to trigger flowering in the first week of June (maybe a little later this year). The grain can then develop over the summer and is harvested towards the end of August. Autumn grown wheat starts to grow then sits out the cold and dark winter. Flowering in these varieties is triggered by this exposure to a period of cold termed vernalization. When the spring arrives the plants are primed to flower in response to the lengthening days. Autumn-sown wheat typically matures earlier in the summer due to this head start.
This means the crop does not have to be harvested all at the same time. Only in the tropics is there enough energy from the sun to permit several growing seasons per year. In Vietnam for example they can get 2-3 rice harvests each year. Wheat cannot grow in these high temperatures, and its flowering is adapted to the long days we have in the summer of Northern Europe.
Perennial wheat, or a crop that is sown and can be harvested over several growing seasons is of great interest because it only has to be sown once over several growing seasons. But there may be several drawbacks such as the build-up of disease-causing organisms. That's the reason farmers rotate crops so that the same plant is not grown on the same ground each season."
9. How about a carnivorous wheat plant to cut down on use of pesticides? It would have sticky traps around the stem. (@SAPS_News)
PH: "There are some wheat varieties already (bred conventionally) which have natural pest resistance to Orange Wheat Blossom Midge. Other varieties overseas are resistant to greenbug or hessian fly which is a massive problem in the US. In the UK, I was talking to a breeder yesterday who is desperate for wheat bulb fly resistance – barley has it, but wheat doesn’t. Not sure about sticky traps on the stem working in the short term – they would probably just attract lots of fungal spores instead!"
8. Should we breed wheat with much higher nutritional value so requiring less weight yield per hectare to feed 'x' mouths? (@EwenMcEwen)
RK: "I'm not sure what is meant by "nutritional value" here. The wheat grain comprises typically 10-13% protein, 10-15% water, with the rest being mainly starch. The "nutritional value" of wheat is therefore overwhelmingly associated with its starch - you should think of wheat as an energy food. Its protein is important more for determining how the dough behaves than for supplying dietary protein; most of our dietary protein is provided by meat/fish, dairy products, eggs and pulses. Nevertheless it is possible to breed for higher protein wheat, although the nutritional quality of this protein is not too good (lacks lysine) and gains in protein generally come at the expense of overall yield."
7. "My super wheat would be gluten free." (Jon Poole)
"As the daughter of a coeliac, gluten free wheat would be amazing but only if the flour had the same properties as standard flour." (@ClaireDraper1)
"I would want a wheat strain that was gluten free." (Victoria Broadway)
MB: "Gluten is the protein in wheat grains that gives dough its elasticity for bread making. It also provides valuable protein nutrients. If wheat was gluten free it would not have these attributes and would not make good bread. It may be possible to alter the specific proteins in gluten to reduce their potential to cause coeliac disease. This could be done by GM or by genome editing if we new the exact changes to make but we don't know this. However, these changes could influence bread making quality. In the interim, food labelling for gluten containing products (it gets into the most surprising foods) helps sufferers to avoid gluten."
RK: "It is possible of course to process the flour of a normal wheat and so produce a gluten free flour. But as MB points out, you won't be able to make a loaf of bread with it (ok for crackers and biscuits). The question is whether biscuits made with gluten free wheat flour would taste any better than something made from rice flour (rice makes no gluten)."
6. Attempts have been made to breed C4 rice [this would boost yield by enabling the plants to devote most of their energy to carbon-fixing, and thus to growth]. Should future superwheat have C4 photosynthesis? (@mattaudley)
RK: "The C4 pathway evolved as an adaptation to the high light intensity and high temperatures typical of warmer parts of the world. The C4 process is somewhat more efficient in terms of fixing solar energy than the C3 one, but only where the temperature and light intensity is high. So while it makes sense to think about converting rice into a C4 type, given that rice is a tropical crop, the fact that wheat is a temperate crop (it is grown in warmer places such as India and Australia, but only during their winters) implies that it is not likely to be a very sensible idea."
PH: "We’d love to turn wheat into a C4 crop. Even in temperate UK summers, a high proportion of fixed carbon can be lost again because of photorespiration and C4 metabolism would help enormously. However this would require not only a change in metabolism but also a change in leaf structure. It remains a long term goal. Researchers like Julian Hibberd at Cambridge and Martin Parry at Rothamsted are looking into making crops more efficient in these ways."
5. "Wheat that has big, low GI grains?" (@halften)
PH: "Breeders routinely measure grain size as it is a key yield component. However, active selection for large grain is often at the expense of grain number and overall yield can actually decrease. All things being equal, larger grains will have a higher proportion of endosperm relative to bran, which makes them preferable for milling (higher flour extraction rates) and bioethanol/distilling (more starch available to turn to alcohol). Low glycaemic index (GI) is trickier: wheat products made from white flour are usually classified as high GI. In order to make them low GI you need to change the nature of the starch itself – the goal here is “resistant starch” – by altering part of the starch biosynthesis pathway. Wheat can be difficult to work with as it is a hexaploid – it has three entire sets of chromosomes, the A B and D genomes – so even if you are able to change one important gene then there are usually two other versions that still work. Research groups all over the world are looking at developing cereals with modified starch characteristics, including UK researchers at NIAB and JIC."
RK: "GI (glycaemic Index) is a ranking of carbohydrate containing foods based on their effect on blood glucose levels. Most of the wheat grain is starch, and the moment it is ground into flour, this will inevitably up the GI of the product (eating a whole grain, as opposed to a milled one, will drop the GI). So I'd suggest that for those people who need to be concerned about GI (primarily diabietics), the way to approach this is to control their diet and the preparation of their food, rather than to be concerned with the GI of the raw product. It's hard to imagine what a wheat grain could be if most of it was not composed of starch. It may be that altering the composition of the starch could affect the GI of the flour, but is the effort to do this worthwhile?"
4. "Short-stemmed wheat?" (@halften)
RK: "The "Green Revolution" wheats, which were introduced in the 1960s and 1970s, were based on exactly this idea. The first of these were produced by crossing with short-stemmed plants (called "semi-dwarf") discovered in Japan, although other sources of semi-dwarfism have in the meantime been exploited as well. Almost 100% of modern varieties, both in the UK and around the world, are semi-dwarf. Short stems have two advantages: (1) the stems are stronger and therefore less likely to fall over, and (2) because less energy goes into making a shorter stem, more is left over to make grain. Fully dwarf wheats are known, but there seems to be a threshold for the plant's height below which yield and fertility dips. So it's unlikely that breeding for shorter varieties will be advantageous; in fact the consensus for a long time has been to breed for "tall dwarf" types, since these seem to be the more vigorous."
3. "Take-all' resistant wheat?" (@TinaBarsby_NIAB)
PH: "Take-all' is a soil-borne fungal disease which can severely affect the root systems of many cereal crops and have a big impact on yield. It builds up quickly in the soil if wheat is grown in the same field for successive seasons, and is one of the main reasons why “second wheat” (wheat grown after wheat) doesn’t yield as well as “first wheat” (wheat grown following a non-cereal crop). Scientists at Rothamsted have shown that varieties differ in the rate at which they build up take-all levels in the soil. However, it seems that once take-all is there in the soil, wheat (and its close relatives within the Triticeae, including barley and rye) has little natural resistance.
Oats, on the other hand, do show resistance. Scientists at JIC and NIAB are working together to see whether the take-all resistance from oats can be transferred to wheat: this cannot be done through crossing (the species are too distantly related) so a GM approach is being used instead."
2. "Will the newly developed "super wheat" be more effective in out-competing weeds?" (Adrian Belton).
PH: "Many of these breeding lines show vigorous growth habit and high biomass. These are the type of traits which should help the crop to compete against weeds, although we have not grown any experiments specifically to look at this character."
1. "How about very salt tolerant wheat that could be grown on rafts at sea? This could help solve problems of water and land requirements for food production." (@Toby_Bruce).
MB: "It is possible to grow plants that float on rafts in water that contain the correct balance of nutrients for growth. This is called hydroponic growth and is widely used for horticultural crops such as tomatoes grown in greenhouses. It's not used for wheat as it is a crop that is grown in huge areas to produce the 600 million tonnes we need each year. So it has to be grown on land to achieve this yield cheaply and sustainably. But there is a lot of work going on to make wheat more salt tolerant so it can grow in soils that are currently not suitable for wheat - e.g. in the Gulf and Australia. This work is done by hybridising wheat with a related wild grass called Agropyron. This plant grows on the seashore of the Eastern Mediterranean."
PH: "Adding to Mike’s point, there are vast areas of Australia that used to be suitable for growing crops but the soils are now too salinated because of irrigation. This is going to become a bigger problem so the need for salt-tolerant crops is growing. If we were to grow wheat on rafts at sea we’d need hovercraft seed drills and combine harvesters too!"
RK: ""Apart from the idea of exploiting salinity tolerant relatives of wheat mentioned by MB, there is also a good deal of interest in trying to improve tolerance by transgenesis, since this approach does seem to work in a number of model plant species. Getting to this point in wheat is still a long way off though. Incidentally, among the major crops, wheat is one of the most salinity tolerant that there is (rye and barley are a bit better)."
Our Q&As answer the questions people put, which may mean that some parts of a subject are covered well and others not. If there is an issue that you think is not tackled, you are welcome to send a follow up question to our plant science panel