Regional Variation In Sus2 In Wheat.

Wheat is an important staple crop, providing about one-fifth of the calories consumed by humans worldwide. The enzyme sucrose synthase 2 plays an important role in grain-filling. A recent study of the sucrose synthase 2 gene described two alleles for the sequence encoding this enzyme in the B genome of hexaploid wheat. These were reportedly associated with either higher (HapH) or lower (HapL) thousand grain weight among a set of modern Chinese wheat cultivars. In order to facilitate genotyping for the Sus2 alleles, we developed a CAPS marker for a diagnostic SNP. We surveyed 168 hard winter wheat cultivars from the U.S. Great Plains and 48 spring wheat lines from CIMMYT. We found that the predominant allele is HapL.  We continue to screen U.S. wheat cultivars for sucrose synthase 2 while also investigating the possible role of the polymorphism in grain weight.