The overall aim of the proposed project is to develop and test strategies for manipulating the frequency and distribution of crossover (CO) formation during meiosis in barley. The ability to control and manipulate COs and consequently genetic recombination in crop plants will improve the speed and efficiency of plant breeding, an important tool that is likely be increasingly important in providing food security for the 21st century. This would be particularly useful for crop species such as barley and wheat where a highly skewed distribution of CO events means that up to half of the genes rarely if ever recombine. As a consequence a substantial proportion of the chromosomes are inherited together as a large linkage block, preventing the generation of novel gene combinations and subsequently the release of useful variation that could be exploited in breeding programs. Thus changing the distribution of recombination events would release previously inaccessible genetic diversity. We have already shown in the model plant, Arabidopsis that chromatin and chromosome organization contribute to the determination of CO distribution and frequency. Further we have also demonstrated that by using chemicals that affect chromatin condensation we can alter the distribution of COs in Arabidopsis. In this project, a survey will be carried out to identify barley genes that have been implicated in chromatin modification in Arabidopsis. Efforts to moderate recombination will be either by developing overexpressing or RNAi lines. Confirmation of the attempts to manipulate recombination in barley will be by using two strategies: Firstly, cytological analysis will be used to determine the number and distribution of crossovers. Secondly, test lines will be made and used for the demonstration of a significant change in recombination frequency in defined genetic intervals as a result of the modifcation in chromatin organization.

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There are major opportunities to increase crop resilience to climate change by increasing diversity. In the UK, weather patterns are likely to become more variable; with increased frequency of droughts, floods and short spells of high temperature stress (11). These changes will render UK agriculture highly vulnerable, with sudden temperature changes, rather than the mean rise, likely to have major effects on agricultural productivity (11; 24). The most economically important crop in the UK is wheat. The interaction between crop development and temperature is complex, but it has been demonstrated that the most vulnerable stage is at flowering (anthesis) (e.g. 6). The intensity and the duration of an extreme weather event affects the period of grain filling and yield reduction is directly linked to maximum temperature stress (2). These sudden, extreme events are distinct from the mean changes in global temperature; gradual increase enables selection of characteristics that improve genetic adaptation to an environment (16) whereas sudden events are considered to be largely beyond the threshold of cellular function. Plant communities with high species diversity have a greater resilience to environmental variations, in terms of (i) resource use (22); and (ii) the stability of biomass production (10). In applying these ecological principles to arable systems, the risk of crop failure can be reduced by increasing crop diversity by harnessing the complementation between different genotypes. At anthesis, an extension of this vulnerable growth stage will increase the chance that a number of individuals will escape the extreme event by flowering before, or after it. In winter wheat, the genetic mechanisms controlling ear emergence and anthesis are categorised according to their environmental interaction. Twenty eight to 56 days of cold treatment (vernalization) induces ear emergence. Genes shown to control vernalization requirement include Vrn-A1, Vrn-B1, Vrn-D1, and Vrn-B3 (14; 15). Varieties can also be categorised according to daylight (photoperiod) requirement. In bread wheat this difference is largely controlled by Ppd-D1 and Ppd-B1 (17), dominant alleles which confer early ear emergence through photoperiod insensitivity. These genes have profound effects on mega-environment adaptation but a third set, earliness per se (eps) genes, can mediate developmental rate independent of specific environmental signals (19). The vernalization and photoperiod genes confer environmental adaptation; but the eps effects facilitate more subtle manipulation of the life cycle for regional adaptation. The advent of whole genome genotyping and Quantitative Trait Locus (QTL) analysis has allowed the identification a number of important eps effects segregating in Western European elite germplasm; a large proportion of the genetic variation in ear emergence can now be accounted for (8). The eps genes describe the mean flowering time point, but variation in genotype can result from: (1) Time of first anthesis; (2) Duration of anthesis within a single ear; (3) Duration across tillers; and (4) Time of day for peak anthesis. Further genotypic effects involve absolute temperature tolerance at seed set. This proposed research aims to test the hypothesis that: greater genotypic heterogeneity increases crop resilience under increasing climatic stress. The single character of flowering has been selected to test the proof of concept. The proposed research will develop new genetic markers for heading date. NILs for the UK eps QTLs and two CCPs, one heterogeneous for eps genes alone, and the other with a wide genetic background, will be dissected genetically and physiologically. The performance of the different genotypes to specific timed heat stress events will determine the contribution of flowering diversity to crop resilience.

Iin BBSRC Project BB/F014295/1 we identified genes whcih are responsible for determing the soluble non-starch polysaccharide (NSP) content and extract viscosity of wheat grain. Using a GM approach to suppress the action of these genes, we produced wheat plants where NSP content and extract viscosity was lowered by 70-80%. This low-viscosity property would be highly desirable in wheat varieties for whisky and animal feed uses, however a GM approach is not possible due to regulatory costs and consummer resistance. Here we intend to start developing a low-viscosity wheat using the non-GM approach of TILLING to find versions of these genes (alleles) which are inactive. By the project end, we will have identified such alleles for all the target genes and established whether they confer the low-viscosity property and check that there are no adverse effects. Our breeding partner will then begin the process of inroducing these alleles into commercial wheat varieties.

Wheat is an important agricultural crop in the United Kingdom. Greenfly (aphids) can reduce grain quality and yield by direct feeding and transmission of diseases to this crop and they need to be controlled. The Department of the Environment, Food and Rural Affairs and the agricultural industry have invested much effort into controlling these pests and others, including fungi and weeds, with pesticides, but there is concern that excessive use of such agents could harm the environment and pass into the human food chain. Attempts have been made to reduce pesticide use by transferring insecticidally active agents into wheat from other organisms by genetic modification. However, many plants species can mount their own defence by producing small amounts of natural chemicals that can deter invading pests. We plan to exploit this property to develop alternative, more environmentally compatible pest resistance strategies for cereal crop plants. Specifically, we are interested in the hydroxamic acids (HAs), a family of compounds produced in wheat and other cereals that defend plants against pests. These chemicals reduce the development of aphids and may deter other insects and weeds. The potential of HAs to control pests in cereals has been intensively studied and, the pathway involved in their biosynthesis within the plant is now known. We plan to examine HA production in wheat varieties that have varying degrees of resistance to pests and disease to confirm that these compounds do indeed have a significant role in aphid resistance. Besides differences in HA levels in these varieties that can be detected under normal conditions, we will exploit ways of increasing production in the wheat by investigating the action of other natural plant chemicals, called plant activators, which can cause increased production in the defence chemistry of plants. In this way we hope to develop means to switch on the production of the plant's natural defence compounds only when necessary, thereby conserving the plant's energy and reducing the development of pest resistance. In addition to demonstrating the effect of high levels of HAs on aphids, we will also investigate their effects on other insects such as gout fly, and to weeds such as black-grass. We know the genetic backgrounds, or pedigrees, of the varieties that we have chosen to study, so we will be able to identify the original parents of wheat varieties that produce high levels of HAs or that are capable of increasing production by the action of the plant activators. Therefore, by the end of the project, working under more practically oriented funding programmes, we will develop our findings together with industrial partners to produce new varieties of wheat that will be able to protect themselves more effectively in the face of a pest attack. This will involve breeding techniques to introduce high production of HAs into wheat plants that can grow in the United Kingdom. The HAs are naturally produced in the roots and green tissue of the plant and so do not influence the nutritional value of the seed from which we make flour for food production, but we will ensure that high HA producing varieties do not show detectable amounts of HAs in the grain. However, full human risk assessment would be part of the work done following this project. Although we can only speculate on how valuable increased HA production will be in developing new means for controlling pests on wheat, we know that HAs are antagonistic to a range of pests, weeds and fungal pathogens. We have established chemical analytical and molecular biological methods for analysing the natural chemicals and associated genes involved in the production of these materials and we have, in preliminary studies, demonstrated increased production of HAs with the natural plant activator chemical, cis-jasmone.