Changes in high molecular weight glutenin subunit composition can be genetically engineered without affecting wheat agronomic performance

The genomes of modem cultivars; have been painstakingly selected for the presence of favorable alleles at multiple loci, which interact to produce superior phenotypes. Genetic transformation provides a tool to introduce new genes without altering the original gene combinations. However, the random genetic and epigenctic changes sometimes generated by the transformation process have been associated with losses in agronomic performance. The agronomic performance of 50 transgenic wheat (Triticum aestivum L.) lines containing additional copies of native or modified high molecular weight glutenin subunit (HMW-GS) genes and the selectable marker bar, their untransformed parent 'Bobwhite', four lines containing only bar, and 10 null segregant lines were assessed in small plot trials over 2 yr and three locations. Most of the transgenic lines did not show significant changes in performance relative to Bobwhite, although the transgenic lines as a group tended toward lower performance. Null-segregant and bar-only lines performed similarly to Bobwhite. No relationship could be established between performance and particular transgenes or their expression levels. Despite the overall lower performance of the transgenic lines, many with agronomic performance equivalent to Bobwhite were identified. These findings suggest that extant techniques for genetic engineering of wheat are capable of producing agronomically competitive lines for use as cultivars or parents in breeding programs.