Flowering in wheat results in the production of grain that is harvested for human, animal and industrial use. Yield is a product of the number of flowers and the proportion of the flowers that successfully set grain. Wheat yields in the UK are generally high but some varieties show infertility (a low proportion of flowers setting grain) under certain environmental conditions. An example of this problem occurred in the winter wheat variety 'Moulin' in the mid 1980's when poor grain set caused losses to growers of up to 90%. Wheat infertility remains a serious threat because a variety with this weakness may slip through the current trialling system and give a serious yield failure. In addition, lower and less obvious levels of infertility may be suppressing wheat yields. Each 1% loss in fertility is estimated to cost £18m to the UK (i.e. 15mt production at a grain price of £120 per ton). Eliminating alleles that cause infertility will therefore enhance yield and protect against yield failure. Despite the seriousness of this problem very little is known about the genes that make some varieties vulnerable to infertility. To address this, Nickerson-Advanta UK Ltd, RAGT Seeds Ltd and KWS UK Ltd, who produce 95% of the current wheat varietes in the UK, have initiated a project in collaboration with the Home Grown Cereals Authority (HGCA), the Scottish Agricultural College (SAC) and the John Innes Centre (JIC). The companies will provide doubled haploid (DH) populations between parent known to differ in vulnerability to infertility. These popluations will be grown by SAC in sites known to induce reproducible levels of infertility. By combining this with genotying data it will be possible to identify quantitative trait loci (QTL) that control the trait. This will allow breeders to select against these undesirable effects. Five diverse populations will be studied, and a primary aim is to determine if there are one or several genetic causes of infertility. This is important for developing a strategy to combat this problem. Results will be tested in a larger collection of varieties and lines provided by the companies and results will ultimately feed through into new testing regimes that will help prevent 'at risk' lines from reaching the market place.

Rhynchosporium leaf blotch of barley, caused by the fungus Rhynchosporium secalis, is of increasing importance in world agriculture. It is the most serious disease on winter and spring barley in the UK, causing substantial losses nationally, despite expenditure of £50M per year on fungicides. The disease is difficult to control with fungicides, as the fungus can exist for a long period in the crop without causing symptoms. A severe epidemic may then emerge without warning. The sources of infection responsible for such epidemics are not well understood. We have recently discovered, for instance, that contaminated seed may be an important primary source of the disease. This project aims to clarify the origin and early dynamics of epidemics using molecular techniques (quantitative PCR) that can detect and quantify the DNA of the pathogen in barley plants before symptoms occur. The same techniques can also detect genetic characteristics of the fungus, such as mating type, virulence, and genes responsible for resistance to fungicides. Each season, epidemics will be monitored on both winter (October-sown) and spring (March-sown) barley. Work will also be done on historical spring barley samples archived at Rothamsted over 150 years, and on samples from current crops from at least 10 sites in England, Scotland and Ireland. We aim to study short-term and long-term changes in the pathogen population. Knowledge from this project will be combined with new information from related projects being funded by BBSRC LINK, Defra, HGCA and SEERAD (at ADAS, and in Scotland, SAC and SCRI) to develop guidelines for crop husbandry and agronomic practices to reduce R. secalis population size and genetic variation to achieve sustainable control of rhynchosporium disease of barley.