Control of infertility in wheat by phenotype screening and genetic analysis of varieties and breeding lines

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.

Environmentally induced infertility in wheat is a serious threat to yield. The low yields of the variety 'Moulin' in the mid 1980's are an example of the problem, which is still detected in plant breeding programmes. Vulnerability to infertility is difficult to eliminate because very little is known about its genetic basis. To address this we will exploit the availability of doubled haploid populations made form parents with high or low vulnerability. These lines will be field tested in sites known to reliably induce infertility. Five diverse crosses will be used to identify QTL. A primary aim is to determine if there is a common underlying cause or several distinct causes. It is essential to know this in order to develop a coherent strategy for tackling the problem. Once QTL are identified, linked markers will be used to assess whether infertility in a collection 94 additional varieties and breeders' lines can be predicted. This provides QTL validation, which will also be tested using advanced breeding lines provided by the companies. The results will enable new testing regimes to be devised and will provide assays for marker assisted selection than will reduce the risk of inferitlity related yield losses in UK wheat.