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References
BBSRC invests around £78m a year in plant and
crop science research at universities and institutes
across the UK. Through partnerships with the EU
and other international partners, it also supports
research that is helping to improve crop yields in
developing countries across the world.
John Innes Centre
Rothamsted Research
www.jic.ac.uk
www.rothamsted.ac.uk
www.bbsrc.ac.uk
Professor Caroline Dean, John Innes Centre with University of
South California
Mikhail Semenov and colleagues, Rothamsted Research
Rothamsted Research
Professor John Snape, John Innes Centre, with colleagues at the University of Nottingham
Professor Keith Edwards, University of Bristol, and Professor Peter Shewry at Rothamsted Research
Dr John Foulkes and colleagues, University of Nottingham with
John Innes Centre and Rothamsted Research
Dr Dave Laurie, John Innes Centre
Professor Graham Moore, John Innes Centre
Professor Michael Holdsworth and Dr John Foulkes, University of Nottingham with Professor John Snape, John Innes Centre
Dr Dimah Habash and Dr Martin Parry, Rothamsted Research
Dr Mikhail Semenov and colleagues, Rothamsted Research with Crop and Food Research, New Zealand
Professor Peter Horton, University of Sheffield
Dr Adam Price, University of Aberdeen, with Dr Richard Whalley and colleagues, Rothamsted Research
Professor Wayne Powell, Institute of Biological, Environmental and Rural Sciences with NIAB and IRRI, Phillipines
Dr Ratan Yadav, Institute of Biological, Environmental with colleagues in Rural Sciences, ICRISAT, India and University of Cape Coast, Ghana
Professor Andrew Meharg, University of Aberdeen, with Dr Fangjie Zhao
and colleagues, Rothamsted Research
Professor William Davies, Lancaster University
Dr Nash Nashaat, Rothamsted Research
Dr Graham King and colleagues, Rothamsted Research
Professor Keith Lindsey, University of Durham with Warwick HRI
Richard Hayes and colleagues, Institute of Biological, Environmental and Rural Sciences
Dr Eric Ober, Broom’s Barn
Professor Chris Gilligan, University of Cambridge
Professor Brian Kerry, Rothamsted Research
Dr Richard Gutteridge and colleagues, Rothamsted Research
Frank Van Den Bosch, Rothamsted Research and Professor Chris Gilligan, University of Cambridge
Professor Chris Gilligan, University of Cambridge
Professor Bruce Fitt and colleagues, Rothamsted Research
Dr Ratan Yadav, Institute of Biological, Environmental and Rural Sciences with John Innes Centre
Dr Nash Nashaat, Rothamsted Research
Professor John Turner, University of East Anglia
Professor Jim Beynon, Warwick HRI
Professor Matthew Dickinson, University of Nottingham
Dr Paul Hand, Warwick HRI with CSL, CABI and KARI, Kenya
Professor Lin Field and colleagues, Rothamsted Research
Dr Graham Moores, Rothamsted Research, New South Wales Agriculture, Endura SpA, Italy
Dr Kim Hammond-Kosack and colleagues, Rothamsted Research
Professor David Rice, University of Sheffield
Professor John Pickett, Rothamsted Research
secure
harvests
T he world’s population is growing
inexorably and harvests worldwide are
threatened by climate change. Grain
stores must be sufficient to protect
against price volatility and speculation –
particularly in poor, developing countries.
Within a lifetime, regions near the equator
could face agricultural losses of up to
over a third.
BBSRC January 2009
1. 2. 3. 4. 5. 6. 7. 8. 9.
10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39.
Crop productivity increased dramatically
throughout the 20th Century, but
further increases are not automatic.
The scientific challenges in ensuring
adequate food supplies are considerable.
We need to focus on where production
gains are most readily and sustainably
achievable. This means identifying and
selecting crop traits and production
systems that can increase yields in
particular soils and climatic conditions,
and reducing losses to pests and diseases.
To do this requires knowledge of how
plants grow and of the factors that limit
productivity, as well as knowledge of
how they interact with other organisms
and environmental factors. The
following examples illustrate some
of the ways that scientific research
supported by the BBSRC and other
funders including Defra, DFID, EU and
BBRO are meeting these challenges.
Global food security
depends ultimately
on growing enough
crops. Economic,
political and social
factors are important,
but sufficiency and
sustainability of
harvests are the
primary needs.
Harnessing natural diversity
Plant science research reveals how plants
function. It explains, for example, why
leaves and plants are the shape they are,
why plants flower when they do, and why
some are better than others at converting
energy into seeds or growing in poor
soils. It also reveals how plants respond
to stresses such as drought (or flooding)
and attack by pests and diseases.
These are important characteristics
in crop breeding and agronomy, and
the underlying mechanisms can be
harnessed to improve crops.
P
lants vary greatly in shape and size, and grow
across the world under vastly different climatic and
soil conditions. But at a fundamental level they are
remarkably similar. As a result, adaptations, which
have evolved over many thousands of years to enable
plants to tolerate particular stresses or combat pests
and diseases, also exist in relatives of our crop species
and can be incorporated into modern varieties.
Information gained from one species, including the
small weed Arabidopsis (the ‘laboratory mouse’ of
plant science) is often directly applicable to complex
crops such as oilseed rape, wheat, rice and maize.
Manipulating plants for food stretches back over
thousands of years. The weedy wild relatives of some
crops are virtually unrecognisable from today’s high
yielding varieties. Familiar crops such as broccoli,
Brussels sprouts and cabbage have all arisen by selection
and breeding from a common ancestral gene pool.
Flowering time
Plant breeders are able to alter traits such as height
and shape; the rate of growth and the time of
flowering; as well as sensitivity to pests and disease.
But plant genetics is often complex; involving the
concerted action of many different genes, which are
influenced by seasonal and environmental factors.
Many plants survive winter by suppressing flowering until
temperatures rise. They need a spell of cold weather to trigger
flowering. But the amount of cold needed for different plants
depends on the conditions in which they live. Changes to the
length or severity of winters threaten this delicate balance; and
increase the risk of crops failing to flower or flowering too early.
Long term sustainability is an increasingly important
factor. High yields have to be achieved predictably
year after year in ways that sustain soil fertility for
future crops, keeping the agricultural ecosystem
working, without harming the environment.
The FLC gene plays a key role in delaying flowering over
winter. Subtly different forms of the gene exist in ‘varieties’
of Arabidopsis from the Arctic Circle to near the Equator,
determining how the plants control flowering as winter
progresses. In UK ‘varieties’, for example, a four-week cold
snap is enough to switch off FLC and trigger flowering, but
in Swedish ‘varieties’ 14 weeks are needed. Using variants
of corresponding FLC genes in crops could help breeders
to time flowering in line with changing weather patterns.[1]
Arabidopsis
Genome analysis of this small weed provides a guide
to the role of corresponding genes in major crops.
Increasing crop yields
Crop yield is determined by a complex
mix of genetic and environmental factors.
Ultimately, it depends on how much
energy the plant captures from sunlight
and how efficiently this is converted into
a harvestable product (e.g. grain or leaf).
Wheat:
W
heat is genetically complex, making
it difficult for breeders to identify and
select combinations of genes to improve
performance. The bread-making species
Triticum aestivum, for example, has three sets
of chromosomes. Nonetheless, researchers
are mapping the wheat genome, and have
found combinations of genes that have
general effects on wheat yield and some
with very specific effects. These include
some that influence a plant’s reserves of
stem soluble carbohydrate. The higher the
reserves the higher the yield can be.[4]
O ptimising crop yield involves trade-offs. The height
of a plant and the size, shape and angle of its leaves
affect how much sunlight it can capture. A big leaf
canopy at the top of a tall plant captures this energy
very efficiently and blocks the light from reaching the
base, so stopping weeds from growing there. A fastgrowing canopy also stops early-season rain from
penetrating the crop and so reduces the risk of fungal
spores splashing up from the ground. And rapid stem
growth in tall crops quickly moves the upper leaves
away from lower ones that can harbour these spores.
By identifying the linkage between genes
for easily observed ‘marker’ traits and those
that affect crop performance, scientists
have compiled libraries of DNA sequences
of wheat and other crops that are used in
the crop improvement programmes of major
international breeding companies. This
approach is helping to identify markers for
processing traits such as flour quality. A new
pan-European analysis of the composition of
grain from over 150 cereal varieties provides
the first clues about how they rank in terms
of the beneficial compounds they contain,
enabling breeders to combine high yield with
good milling qualities and health benefits.[5]
But all these benefits of tall, fast growing crops must be
weighed against the cost of less productive lower leaves,
the greater risk that plants will fall over in wet and windy
conditions, and the fact that they put proportionately
less of their energy into grain than shorter plants.
Scientists at Rothamsted Research (RRes) have
developed computer models that show the complex
interactions of factors such as weather, cropping, sprays,
fertilisers and machinery on yield and environmental
impact. These help farmers to optimise systems, for
example by making the best possible use of nutrients in
the soil, whilst retaining soil fertility for future crops.[2]
Hereward, a modern
short-strawed wheat
variety (foreground)
and an old variety,
Squrehead’s Master. The
former has smaller, more
erect upper leaves that
let light pass lower down,
so increasing yield from
lower leaves but allowing
more weed growth.[3]
Yields of UK winter wheat are currently
limited by the number of grains in the ‘ear’.
However, yield can be increased in plants
that (a) grow faster before flowering and then
produce more grains, and (b) have higher
reserves of stem soluble carbohydrate from
which to fill the grains. Researchers at
Nottingham, in collaboration with
the International Maize and
Wheat Improvement
Center (CIMMYT), have
developed lines of
wheat by crossing a
‘large ear’ wheat,
developed at
CIMMYT in Mexico, and a UK elite wheat,
with the aim of incorporating ‘longer ears’ into
UK adapted varieties. The lines have two to
three more spikelets than conventional wheat.
The team is working with a plant breeding
company to understand the physiology and
genetics of the large-ear variety, and to
increase grain production in elite varieties.
Predictable and stable quality of harvested
materials is very important commercially. In
collaboration with wheat breeders, the HGCA
and downstream industries, researchers at
the John Innes Centre (JIC), the University
of Nottingham, RRes and Harper Adams
University College, are investigating the factors
controlling Hagberg Falling Number (HFN), a
key determinant of wheat grain quality. The
findings will help in identifying ‘smart screens’
that breeders can use to improve HFN, as well
as identifying key combinations of genes.[6]
In traditional cool, wet UK summers, lateflowering crops have an advantage because
they fully utilise the long growing period.
But to cope with much hotter and drier
summers, we will need wheat varieties like
those of Southern Europe that flower and
amass yield earlier, but which are otherwise
suited to UK conditions and markets. A
gene in barley could hold the answer. It
controls the plant’s response to the length
of daylight. Different varieties of wheat and
barley have slightly different forms of the gene
and flower at different times. Understanding
this natural variation will help breeders to
optimise flowering time to UK climate.[7]
Rice and other
tropical crops
Increasing crop yields
Getting
novel traits
into wheat
P
lants need sunlight but they also need to
be able to dissipate potentially damaging levels
of energy if they are to resist enviromental
stress. This is a particular problem in parts
of South America, Africa and Asia. By
studying how some variants of Arabidopsis
can survive under conditions of excess light
intensity, scientists discovered that changes
in xanthophyll pigments bound to the lightharvesting complexes found in plant cells
increases the extent of stress tolerence.
Some of wheat’s wild relatives
have potentially useful traits such
as drought-tolerance and diseaseresistance. But these cannot be
bred into commercial varieties
because of a mechanism in wheat
that prevents its chromosomes
from swapping genes, except
with other wheat plants.
With EU-funding and BBSRC-DfID support
respectively, these researchers have
collaborated with local research institutions
to explore whether genes for similar
protective mechanisms can be used to
improve productivity of bean crops in South
Africa, and rice in the Philippines.[12]
Scientists at the JIC have found
that a gene called Ph1 senses
when parental wheat chromosomes
match and allows them to cross.
They are identifying ways to block
Ph1 temporarily so that breeders
can cross wheat varieties with
wild relatives to obtain hybrids
with new traits. Once a useful
gene is incorporated, Ph1 would
be switched on again, fixing
the new gene in subsequent
generations of the crop.[8]
A round 30% of the two million
hectares of winter wheat produced
annually in the UK is grown on droughtprone soils. But research suggests
that, by 2050, heat-stress may be a
much bigger problem than drought.
For early-flowering wheat varieties,
such as Avalon, higher temperatures
would bring forward maturation and
wetter winters would provide the
water they need. But later flowering
varieties would be adversely affected.
Crop trials by scientists at the JIC
and the University of Nottingham
show that a long-lasting green flagleaf area is by far the most important
determinant of high yield in winter
wheat during the late season drought.
These researchers have identified,
and located on wheat chromosomes,
genes that could offer new sources of
drought-tolerance for breeders.[9]
Around the Mediterranean basin the
situation is very different, with water
shortages severely reducing wheat yields.
As part of a European project coordinated
by RRes scientists, the search is on
for combinations of genes that control
how pasta-making varieties sense and
respond to drought, and which traits are
needed for stable high yield. This involves
correlating data about gene activity under
different conditions with physiological
changes in crop performance.[10]
Having the most appropriate crop
varieties is only the start. Growers need
to know how to manage crops in terms
of sowing and harvesting times, soil
conditions, and fertiliser and pesticide
interventions. Predictive computer models
that assess the likely impact of climate
change on grain yield, yield variability
and geographical distribution
are helping farmers to
optimise land use in a
changing climate.[11]
Climate change poses a risk to rice production,
the staple crop for over two billion people. At
the University of Aberdeen, researchers are
identifying the basis of how varieties of rice
differ in drought-tolerance. Marker assisted
selection is also being used to develop
drought-tolerant varieties. In particular, and with
scientists at Rothamsted Research, work is
underway to identify genetic markers that reflect
the ability of rice varieties to penetrate hard
soils – a key feature of drought tolerance.[13]
Irrigation
Irrigation waters accumulate salts that
can damage plants. We need to know
more about the mechanisms by which
plants protect themselves, as a step
to developing more resistant crops.
Using Arabidopsis as a model species,
research at the University of Glasgow
shows that some protease enzymes
are critical in protecting plants, and that
varieties with high levels of proteases are
much more tolerant of high salt levels.
Arsenic contamination of groundwater
is a problem in some irrigated rice
fields in South East Asia. The search
is on to improve local varieties of rice
by breeding-in genes from varieties
that export only low levels of inorganic
arsenic to protect human health.[16]
A BBSRC-DfID funded project is using
new techniques to identify rice genes that
confer tolerance to extremes of climate and
attack by disease, with a view to developing
new rice varieties for Africa and Asia.[14]
A partnership between scientists in Wales,
India and Ghana is exploring the genetic
make-up needed to increase the drought
tolerance of pearl millet (below), a crop
that provides food security to around 500
million people in Africa and Asia.[15]
Increasing crop yields
Increasing crop yields
UK grasses
Cotton
When plants are at risk of drying-out their roots send signals to the leaves to close leaf pores and conserve water. Research at
Lancaster University shows that Partial Root Drying (PRD), in which alternately some roots are watered and others are not, slows
leaf growth but enables plants to maintain themselves on low levels of water. An EC-funded study in Turkey showed that cotton
plants grown with PRD used half the water and could be harvested three weeks earlier than those irrigated conventionally.[17]
Oilseeds
Y ield is not the only factor in
determining grass quality as a
forage crop. Levels of water-soluble
carbohydrate play a crucial role
in improving digestibility and the
quality of silage made from grass,
as well as in improving the efficiency
of nitrogen-use and reducing
pollution from excreted nitrogen.
Working with British
Seed Houses (part of
Germinal Holdings Ltd),
and with support from
BBSRC and Defra,
researchers have
developed a perennial
ryegrass variety,
AberMagic (above), that
combines several key
attributes including:
high digestibility, high
dry matter yield and
good persistency,
high quality silage
and good nitrogenuse efficiency.[21]
I ndia is the world’s largest grower of oilseeds, but at
yields below half of those obtained in developed
countries. The main problems are drought, poor soils,
low inputs and losses to pests and diseases.
Collaborative research between RRes and Indian
scientists has led to the development of droughttolerant breeding lines of rapeseed-mustard, and
has shown that varieties can be bred successfully
for use on rice-fallow land, which otherwise would
be left uncultivated.[18]
New research between RRes and the University of Delhi,
Pant University of Agriculture and Technology and
Krishida Seeds Ltd is using a common brassica
genome sequence to identify options for
increasing oilseed productivity and
disease resistance.[19]
Researchers in the UK are (i) identifying
genes that regulate oil production in
embryonic Arabidopsis with a view to
targeting equivalent genes in crop species
such as oilseed rape, and (ii) exploring options
for blocking enzymes that breakdown stored oils in
oilseed species. Both approaches offer breeders the
prospect of being able to increase yields significantly.[20]
UK Sugar beet
The sugar-beet crop in the UK is grown in
the dry east, where drought is an increasing
risk. With industrial funding, scientists at
Broom’s Barn are assessing a wide range of
genetic material to identify varieties that can
grow well under drought conditions and still
produce good yields of sugar in their roots.
They have found some useful markers, such
as green crop canopy size, which plant
breeders can use to predict drought-tolerance,
and are working with an international seed
company to accelerate selection of new
drought-tolerant varieties.[22]
Reducing the impact of pests and diseases
Around 25% of the world’s crops are
lost to pests or diseases. In some
circumstances, climate change will
make this worse for some pests and
diseases as the environment has
more effect on their development. For
instance, milder winters enable aphids
to survive and so damage crops earlier
in the growing season. There are also
ongoing challenges from pests and
disease-causing organisms that have
evolved to overcome pesticides, and
from the restriction or banning of some
effective control agents because of
concerns about environmental impact.
Soils
R
esearch is providing several options for improved control of pests
and disease including:
Efficient disease control requires an understanding
of the interactions between soils, crops and pests
and pathogens in the soil. For example, work at RRes
is characterising how populations of microbes in the
soil may be used to help suppress fungi that attack
roots and nematodes. Research supported by the
EU and DfID has led to a novel biological control
agent, based on a strain of a natural soil fungus that
is a particularly effective parasite of nematodes.[24]
better preventative, diagnostic and pre-emptive strategies
development of naturally resistant crops
strategies to prolong the effectiveness and sustainable use of
existing pesticides
development of novel control agents (chemical and biological)
The knowledge required for such strategies includes understanding the
mechanisms by which organisms infect plants, and how these might be
blocked; as well as understanding the ways plants respond to attack, and how
these defences might be strengthened. It also includes understanding how
pests and diseases build up and spread between crops, as well as how they,
in turn, evolve to counter to plants’ natural defences and the use of pesticides.
Research at RRes has also shown that maintaining
levels of phosphate in the soil can help to protect
against take-all disease in wheat. Using grass
leys in rotation also delays the risk of epidemics
starting in subsequent wheat crops.[25]
Computer modelling has helped growers in Africa and
Asia to improve yields of their staple crop cassava by
controlling Cassava Mosaic Virus Disease (CMVD),
which is spread by whitefly. The models, generated
from experimental data, revealed that frequent
removal of infected plants is by far the most
effective way of limiting CMVD infections.
Growing resistant varieties, on the other hand,
can prevent disease spread only when whitefly
density is low; although combined use of
resistant varieties and frequent removal of
infected plants can prevent the start of an
epidemic in many cases. The models also
showed that some control strategies can
inadvertently select strains of the virus that grow
faster in plants and so counteract control.[26]
Predicting and
minimising attacks
P redictive modelling of how diseases spread, and the probable impact of
different control methods can identify when and where farmers should intervene.
This helps to eliminate unnecessary spraying and to optimise dosage. But it
can be counter-intuitive. For example, research at the University of Cambridge
shows that, when deploying limited resources to treat disease in two interconnected regions, it is more effective to treat the one with the lower level of
infection first, rather than trying to equalise the level of infection in each region.[23]
Robert Brook/Science Photo Library
Rhizomania is a
serious disease of
sugar beet, caused
by a soil-borne virus
that is spread by farm
machinery. By the
time symptoms
appear the disease
has spread, making
containment difficult.
Field scale control
fails to halt the
disease but farm
scale response,
i.e. responding to
the arrival of
symptoms on
the next-nearest
neighbouring farm
is effective.[27]
Research on the life
cycle and biology of
pests and diseasecausing organisms
underpins several
online forecasting
services that provide
growers with
frequent updates on
when a significant
percentage of
crops is likely to be infected in their regions. This enables
them to prepare controls in advance against diseases such
as light leaf spot, which causes an estimated £30m annual
loss in winter oilseed rape in the UK, and phoma stem canker
that can cause losses of £100m in epidemic years and is
predicted to increase in severity with climate change.[28]
Reducing the impact of pests and diseases
Disease-resistant crops
A
round 500 million people worldwide
depend on the grain crop pearl millet.
Downy mildew disease can reduce crop
yields by up to 80%. Collaborative research
with scientists in India has led to the
breeding of a new variety that is resistant
to attack by the causative pathogen.[29]
Work led by RRes scientists in India has
helped to develop disease-resistant oilseed
brassicas. This involved 5,000 farmers
in training programmes at 73 sites and
has led to increased self-sufficiency in
vegetable oils and enabled short-duration
oilseed production in rotation with rice
where land was previously left fallow. This
has included identifying breeding lines of
Indian mustard and oilseed rape-Ghobi
sarson resistant to multiple strains of the
downy mildew and white rust pathogens,
and lines of oliseed rape-Ghobi sarson
that are tolerant to Alternaria blight and
stem rot under Indian field conditions.[30]
Healthier coconut palms
Working with the Oil Palm Research Institute in Ghana, scientists
at the University of Nottingham are searching genetic varieties of
coconut palm to find types that can resist the lethal yellowing-type
disease called Cape St Paul wilt, which is devastating plantations in
coastal tropical Africa.
Arabidopsis clues to disease resistance
Scientists at the University of East Anglia have
identified genes in Arabidopsis that protect the plant
against a wide range of powdery mildew diseases. They
also showed that when transferred into laboratory tobacco
plants, the genes again provided this protection.
In current research these genes are being tested for their
ability to provide disease resistance in squash – genetically
modified forms of which are widely grown in the USA.[31]
A major programme at Warwick HRI is identifying genes
in Arabidopsis that trigger plants to defend themselves
against downy mildew. These researchers are also
studying the genes in the pathogen that suppress the
plant’s response. Information about the mechanisms of
this ‘arms race’ between the plant and the pathogen will
inform new strategies for breeding durable resistance into
crops and reveal new targets for attack.[32]
The disease is caused by a phytoplasma bacterium. As well as finding
resistant forms of palms, the scientists are also exploring how infection
spreads from palm to palm, so that replanting may be managed to
reduce further losses in future. Transmission by seed is one possible
explanation being investigated.[33]
In related work, the Nottingham team is
investigating the molecular basis of phytoplasma
infection using Catharanthus rosea (Madagascar
periwinkle) as a model system.
...and kale and cabbages
B
lack rot is a bacterial disease caused by Xanthomonas
campestris. It can devastate vegetable crops in warm climates,
such as East Africa, and often destroys entire crops grown by
smallholders. Control of this seed-borne disease is difficult as there
is no effective chemical treatment.
UK geneticists and pathologists are working with crop scientists
in Kenya, using the latest genomic tools in brassicas and
Arabidopsis, to identify genes that confer broad-spectrum
resistance to black rot. This will enable more rapid breeding of
resistance into local varieties. the large-ear variety, and to increase
grain production in elite varieties.[34]
Reducing the impact of pests and diseases
Reducing the impact of pests and diseases
Overcoming resistant pests
New forms of control
C otton boll weevil, whitefly and diamondback moth are among the major crop pests that are
becoming increasingly difficult to control. This is because exposure to pesticides has driven the
selection of resistance, for example individuals that produce much higher levels of enzymes that
deactivate pesticides.
P lants use chemical signals to repel pest species and to
attract beneficial insects that they need for pollination.
By planting companion species with crops this ‘push-pull’
effect can be harnessed for pest control.
Research is identifying the biochemical and molecular basis of pesticide resistance, as well
as the conditions that result in the selection and spread of resistance in insect populations.
From this, scientists have developed rapid diagnostics for detecting resistance and
methods for predicting, and therefore counteracting, its development.[35]
Working with maize growers in East Africa, scientists at RRes
used inter-crop lines of Desmodium to repel stem borers from
A novel approach, developed by scientists at
RRes and New South Wales Agriculture
in Australia, can restore the
effectiveness of conventional
pesticides to which pests
have become resistant.
In partnership with
Italian company
Endura SpA, they have
developed a product
that first inhibits the
pesticide-degrading
enzymes and then delivers
a dose of pesticide. In field
trials in Spain, this approach
achieved 100% control of whitefly that
were previously resistant to the pesticide.[36]
Cotton boll weevil (top, photo by Pest and Diseases
Image Library) and diamondback moth.
New targets for
fungicides and herbicides
H
eadblight or ‘scab’ in wheat costs millions of pounds
worldwide each year, in terms of lost yield and reduced
quality as a result of fungal toxins making the grain
unusable in food or animal feed. There are no varieties
with high levels of resistance and current fungicides
provide only partial control.
By using high throughput screening of the metabolic
compounds produced by the fungus as it causes
infection, scientists at RRes are finding new targets
for novel pesticides.[37]
Scientists at the University of Sheffield and the
agrochemical company Syngenta are combining the
academics’ structural biology expertise with the company’s
identification of new chemicals that have potential as
new generation herbicides. The partnership advances
understanding of how molecular structure determines the
activity of herbicides, and offers industry the opportunity
of novel targeted compounds capable of killing weeds that
have become resistant to conventional herbicides.[38]
The active site of a novel herbicide target (imidazoleglycerol
phosphate dehyrdatase), which binds its substrate between two
manganese ions.
within the crop and a peripheral crop of attractive Napier
grass to ‘lure’ them away from the maize. This dramatically
increased yields, and as a bonus the intercrop suppressed
the parasitic weed Striga, and the border crop provided
forage to rear calves.[39]