Providing access to safe, nutritious and affordable food to the growing global population is a huge challenge (ref 1). To achieve this aim scientists will need to work together, across disciplines, to overcome some major research challenges.
The good news is that certain organisations, such as the Consultative Group on International Agricultural Research, an alliance of international agricultural centres that aim to achieve sustainable food security and reduce poverty through research-related activities, have stated that with appropriate funding a doubling of food production is possible (ref 2).
- Video: Professor John Lucas discusses ongoing crop improvement goals
- Enhancing photosynthesis
- Reducing environmental impact
- Increasing nutritional benefits
- Defeating exotic diseases
- Tougher crops
- Exploiting genome advances
- Improving wheat
- Understanding diet and health
- From food production to economic progress
Duration: 0:00:41 - Video transcript
Ultimately all the food we consume – and all life on Earth – relies on the conversion of carbon dioxide into sugars using energy from sunlight through photosynthesis.
Photosynthesis could be enhanced
Improvements in the yields of major crops could be achieved if scientists can understand how to improve the efficiency of photosynthetic pathways and increase production using the same amount of sunlight.
Not all plants have the same photosynthetic pathways. C3 carbon fixation is one of three biochemical mechanisms, along with C4 and CAM photosynthesis. Most plants use the C3 pathway, but around 25-30M years ago the C4 system evolved many times (an example of convergent evolution); it is called C4 because the first product of CO2 fixation in C4 plants has four carbon atoms, rather than three as in C3 plants.
C4 plants possess distinctive features, particularly in leaf anatomy and biochemistry, which lead to higher photosynthetic efficiency (especially in warm climates) and lower requirements for water. C4 plants dominate many tropical savannahs and grasslands and account for 30% of global terrestrial carbon fixation, even though only 5% of plant species use the C4 pathways (ref 3).
Some major agricultural grass species, such as maize, sugar cane, sorghum and millet, use C4 photosynthesis. Scientists are therefore keen to investigate the introduction of C4 pathways into cereals such as rice and wheat that use the less productive C3 metabolism (ref 2) through conventional breeding or genetic modification. It could provide massive benefits in yield and save water – C3 plants lose 97% of the water taken up through their roots to transpiration (ref 4) and the C4 system raises water-use efficiency compared to the C3 type (ref 5).
Efforts are also needed to increase the sustainability of farming practices, which are responsible for 7% of total greenhouse-gas (GHG) emissions in the UK (ref 17).
Possible solutions include less ploughing, and instead covering the ground with organic residue such as straw to counter weed growth, or rotating crops. Known as conservation agriculture, this avoids damaging soil and releasing GHGs (from ploughing) and can conserve soil structure, nutrients, as well as saving energy (ref 2).
Another strategy includes incorporating nitrogen-fixing capability into non-leguminous plants. Nitrogen is vital for plant growth. Despite making up 79% of the Earth’s atmosphere it cannot be used by plants in that form and plant biomass is often limited by the amount of nitrogen (and phosphorus) they can obtain. This is the reason plants respond with significant extra growth when fertilisers are applied.
A few plants have evolved symbiotic relationships with bacteria that convert (or ‘fix’) atmospheric nitrogen into a usable form. The roots of leguminous plants like peas and beans possess nodules filled with symbiotic bacteria that can convert the inert atmospheric form of nitrogen into compounds usable by plants – the result is that they need less nitrogen fertiliser than crops without the nodules.
Legumes such as White Clover are used to naturally enrich agricultural soils with nitrogen. Image: JIC
Soya and alfalfa are examples of other plants that have this ability. But what if you could understand the mechanism enough (ref 6) to cross the trait into wheat, rice or barley?
The benefits could be enormous (ref 7). Less fertiliser would be needed, which would save time, money, and the energy required to produce the fertiliser in the first place. This would lead to a reduction in greenhouse gas emissions and reduced runoff from fertilisers that can pollute aquatic habitats.
Drought-tolerance in crops is also important for securing future harvests, especially as water becomes more scarce. Nearly three-quarters of the world’s fresh water that is abstracted for human use is used for irrigation in agriculture and the UN predicts that irrigation demands will increase by 50-100% by 2025 (ref 8).
Principal mechanisms to make plants more tolerant to drought include improving water retention in roots, reducing water loss through leaves and changing plants’ reactions to lack of water (ref 9).
Both conventional breeding and genetic modfication (GM) techniques could help scientists enhance plants’ ability to withstand drought. Scientists at Rothamsted Research (RRes, an institute of BBSRC) have collaborated with scientists from India to develop drought-tolerant rapeseed-mustard crops. These varieties can also be used on rice-fallow land, which would otherwise be left uncultivated (ref 10).
As well as yield benefits and reducing fertiliser inputs, scientists are looking at the advantages of incorporating additional nutrients into crops, or improving the post-harvest processing characteristics of certain plants.
Soya beans can be modified to be more nutritious. Image: USDA
Around 2013 a soya variety is set for launch designed to result in fewer unhealthy transfats after processing. A soya bean with higher amounts of omega-3, the fatty acid which can improve cardiovascular health, may also be on the way (ref 9). Scientists at RRes have already developed oilseeds with increased omega-3 content (ref 11).
All plants contain omega-3 fatty acids. However, not all omega-3 fatty acids possess the health benefits associated with the fish oils that are rich in a particular type called omega-3 long-chain polyunsaturated fatty acids. These long-chain omega-3 fatty acids are absent from higher plants; hence the rationale for trying to incorporate them into crops.
At present, omega-3 is harvested from oily fish like sardines and mackerel, which in turn gain their omega-3 from algae (ref 9). Inserting the relevant genetic material from algae into soya beans could reduce pressure on some fish stocks. Such products could also play a part in providing sustainable feed for farmed fish, reducing the inefficient use of wild-caught fish as a feedstock. It remains to be seen, however, how well consumers will take to GM omega-3-enriched products.
The food security challenge cannot be met by just improving plants. Livestock are valuable assets to developed and developing countries and convert inedible resources such as grass and some waste products into items that people can eat.
In many developing countries wealth is measured by head of cattle, sheep or goats, and diseases like rinderpest have in the past devastated livestock numbers across large swathes of Europe and Africa (see Rinderpest: confining animal plagues to history).
Although rinderpest is on the verge of eradication, other diseases such as bluetongue are endemic in some countries and threaten the health of animals and economies in others, including the UK (see Bluetongue: strategy and success).
The African Swine Fever virus. Image: IAH
But unlike rinderpest and bluetongue some diseases have no vaccine. African Swine Fever (ASF) is one of them, and it poses a major risk to pig industries across the world. There is no cure or vaccine, and the highly contagious virus causes a haemorrhagic fever with an extreme mortality rate that can reach 100% (ref 12).
African Swine Fever Virus (ASFV) is endemic to sub-Saharan Africa and persistently infects its natural hosts, warthogs and bushpigs with no disease signs. Its alternate host is the soft tick (Ornithodoros spp.) (ref 13).
Following sporadic outbreaks in Europe from 1957, the virus arrived in Georgia in 2007 and has spread into Armenia, Azerbaijan and Southern regions of the Russian Federation. Scientists became even more alarmed when the virus suddenly appeared in St. Petersburg in north-west Russia, close to the European Union.
Dr Linda Dixon, Head of the ASF research programme at the Institute for Animal Health (IAH, an institute of BBSRC) says their genetic fingerprinting of the virus indicates that it came from South-Eastern Africa, and was transported by ship to Georgia.
The IAH is the specialist diagnostic reference laboratory for ASF on behalf of the World Organisation for Animal Health (OIE) and Defra (ref 13).
It isn't known how the virus jumped from southern Russia to the north of the country. The movement of infected pigs or meat are both possible. The virus can survive for months in cold store meat, and for years in frozen carcasses. All parts of the animal can contain the virus, and contaminated offal and off-cuts fed to pigs are likely to result in infection.
ASF symptoms in a pig.
It took more than thirty years to eradicate ASFV from Spain and Portugal following its appearance there in the 1950s. Control of the disease is achieved by slaughter and strict adherence to movements on and off farms. The virus remains endemic on the Italian island of Sardinia.
Attempts to make a vaccine by conventional means have not been successful. Scientists are removing genes from the virus to see if they can produce a virus that still grows in the pig and induces protection but without causing disease. “We are also identifying precisely which ASFV components induce protection in pigs; these might also be used in vaccine development,” says Dr Dixon.
Optimising crop yields involves trade-offs. Tall plants with large canopies capture light efficiently and shade the ground which prevent weeds growing on the same patch. However, bigger is not always better. Tall, fast-growing plants shadow their own lower leaves, can fall over (lodge) in the wind and rain, and they put more of their energy into inedible stem than edible grain.
Modern cereal varieties are shorter. Image: JIC
Today’s wheat cultivars are much shorter than they were one hundred years ago (try looking at the height of wheat in old paintings – it used to be as tall as the person harvesting it – see Picture gallery: past and present). Modern ‘semi-dwarf’ plants are less likely to lodge and more energy is channelled to the grain rather than the stalk. These varieties of wheat, rice and sorghum formed the basis of the increased yields of the ‘green revolution’ because they responded well to the increased availability of fertilisers (see Modern agriculture and food security – a history).
The semi-dwarf form is a natural variant of wheat that humans have taken advantage of; the gene responsible was identified and characterised only 10 years ago at the John Innes Centre (JIC, an institute of BBSRC). Currently, JIC and RRes scientists are collaborating to identify additional dwarfing gene variants that may provide increased tolerance to an increasingly unpredictable environment.
Many advances and major breakthroughs will come from reading the DNA code of organisms and deciphering the genetic mechanisms of traits that manage plants’ reactions to stresses such as disease and drought.
To this end, the Earlham Institute, an institute of BBSRC, was opened in 2009 to further research aimed at understanding the genetic makeup of organisms and the genetic differences that exist between individuals.
Understanding the genetic mechanisms underlying the synthesis of plant compounds could allow breeders to develop crops with higher amounts of beneficial antioxidants. The plant pigments lycopene and anthocyanin (a flavonoid) both have anti-cancer properties, and could be more concentrated in tomatoes for example.
Plant pigments have proven health benefits. Image: USDA
The use of genome analysis to understand the behaviour of plant pigments could also enhance crop production. For instance, scientists have discovered that changes in another plant pigment, xanthophyll, and the way that it binds to light-collecting complexes in plant cells alters stress tolerance. These researchers are now exploring whether other genes for similar protective mechanisms can improve productivity in beans in South Africa and rice in the Philippines (ref 10).
The International wheat genome sequencing consortium is toiling to decode the wheat genome. It’s a huge task – the species that is used for bread-making, Triticum aestivum, contains three sets of chromosomes and has five times more DNA than the human genome (ref 10).
Decoding the wheat genome will help scientists in many tasks. For example, to understand why crossing wheat with other species is difficult – a genetic mechanism prevents its chromosomes from swapping genes with anything except other wheat plants.
Wheat has a larger genome than a human
However, scientists at JIC have identified a gene, Ph1, which allows chromosomes to cross. Identifying ways to temporarily block the action of the Ph1 gene could allow traits from related plants, such as wild wheats and grasses, to be incorporated into wheat. This would be a huge leap forward and enable a whole range of novel traits to be added, such as drought and salt tolerance, increased biomass and nitrogen-use efficiency, and resistance to insects and fungi (ref 14).
JIC scientists are also determining the best characteristics for winter wheat, which is sown in the autumn (ref 15). Wheat responds to day length and temperature, and these responses can be adjusted to match flowering and maturation times to predicted future climates that have different temperature and rainfall patterns (see Seasonal flower power).
Similarly, scientists at RRes are coordinating a pan-European collaboration to optimise yields from pasta-making wheat varieties under Mediterranean conditions. It’s work that involves matching data on gene activity in the plants cells with physiological changes in the growth of the whole plant.
Meanwhile, researchers at Nottingham University, in collaboration with scientists at the International Maize and Wheat Improvement Center (CIMMYT), are crossing a Mexican wheat variety with more grains per ‘ear’ with a UK variety to increase yields during the UK’s long summer growing period (ref 10).
The food we do produce needs to be as healthy as it can be. Looking to the future, there is a lot that we have to learn about what food does to our bodies, besides providing energy and essential nutrients. The embryonic field of nutrigenomics – the study of how nutrition interacts with the genome and gene expression – could provide valuable new information on how different foods (and nutrients within food) affect metabolism, patterns of gene expression and our overall health and well being.
We understand little about how food affects gene expression. Image: iStock
Nutrigenomics will be partnered by other genomic technologies including metabolomics – which involves the rapid measurement of many small-molecule metabolites (ref 16). The metabolome represents all metabolites in a cell, tissue or organism, and advanced metabolic profiling aims to provide a snapshot of the physiology of any cell and its many biochemical pathways. In time, new fields such as these could provide insights that might improve our food, influence which foods we choose to eat and lead to deeper understanding of how we respond to foodstuffs.
Food manufacturing is the UK’s single largest manufacturing sector and accounts for 7% of GDP, employing 3.7M people (ref 1 and ref 17). Certainly, from farm gate to food plate, agriculture and the food supply chain can be a massive revenue creator for any country.
Many challenges remain, but scientific research can drive development in many countries – not just richer industrialised countries. Surveys have showed that adoption of new maize varieties in West Africa have led more than a million people out of poverty (ref 18).
Therefore, scientific development for agriculture, alongside socio-economic advances, such as agreement on international trade rules, translation of research and technology into practice, and aid for developing countries to support their agricultural development and improvements to infrastructure, can lead to successful, sustainable progress.
- Cabinet Office – Food matters: Towards a strategy for the 21st Century
- New Scientist – Four ways to feed the world
- Nature's green revolution: the remarkable evolutionary rise of C4 plants
- Roots: evolutionary origins and biogeochemical significance
- Ecological selection pressures for C4 photosynthesis in the grasses
- Nodulation independent of rhizobia induced by a calcium-activated kinase lacking autoinhibition
- New research may reduce global need for nitrogen fertilizers
- Water wars, Eureka #2, The Times
- The Economist – The parable of the sower
- BBSRC – The Bioscience Behind: secure harvests
- Rational metabolic engineering of transgenic plants for biosynthesis of omega-3 polyunsaturates
- OIE African Swine Fever
- Wheat meiosis and the Ph1 locus
- Winter Survival Skills, BBSRC Business January 2007
- Human Metabolome Project
- DEFRA – The Future of our Farming
- The economic and poverty impacts of maize research in West and Central Africa