Strategic approach to mitigating weather induced defects of wheat quality

Weather related defects of wheat quality cause about $100 million of crop losses annually in Canada. The degree of down-grading from post-maturity moisture intensity and duration relates directly to seed deterioration and indirectly to biotic infestation. A multi-pronged project was implemented to study genotype response over environment to moisture-induced degrading factors. In post-physiological maturity field weathering studies, loss in the early response factors, test weight and kernel colour, was similar across cultivars, but cultivars with greater initial test weight and better colour retained grade longer. A later response factor, seed sprouting, is being studied under field and controlled environmental conditions in three genetic populations: one each of a white-seeded, a red seeded hexaploid wheat (Triticum aestivum L.) and a durum wheat (T. turgidum L. var. durum) population. Transgressive segregation for resistance to sprouting was found in the durum and the white seeded hexaploid populations; analysis is pending on the third population. The application of DNA mapping to these populations has generated quantitative trait loci (QTL) associated with sprouting resistance. The populations will be tested for cross applicability of markers identified within this project and from elsewhere. Pre-harvest sprout resistant and susceptible lines selected from the white seeded hexaploid population, SC8021V2/AC Karma, are being used to determine gene expression of factors related to grade protection by transcript profiling of early developmental genes using a wheat EST biochip. A field study of the effect of fungal infestation on the induction of susceptibility to pre-harvest sprouting of genotypes varying for resistance to pre-harvest sprouting has been implemented. Kernel blackpoint may also cause down-grading of wheat, and an investigation of environmental determinants of blackpoint across genotypes is underway.