The resistance of transgenic wheat lines against fungal infections in field trials

The transfer of additional resistance genes by transgenesis allows to better understand their function and interactions with the other genes of the plant. This study examines the resistance of different wheat lines against powdery mildew, stripe rust and Fusarium head blight. On the one hand, the race specific resistance gene Pm3b of the wheat landrace Chul has been transferred to the variety Bobwhite, on the other hand, non specific, quantitative resistance provided by chitinase and glucanase genes has been added to the variety Frisal. The trials have been realized under strong infection pressure in order to compare the resistance level of the transgenic lines with their original varieties. In the case of Pm3b descendants, it was possible to include non-transgenic sister lines. The sister lines underwent the same transformation process as the transgenic lines but the transgene was lost after regeneration of the plant by seeds due to segregation. The results show that the additional Pm3b improves considerably the resistance against powdery mildew infections on leaves but also on the ears. Surprisingly, one of the transgenic lines displays improved resistance against stripe rust. Resistance against Fusarium head blight is not affected by the presence or absence of the transgene. Additionally introduced chitinase and glucanase genes did not improve the resistance improvement under the present experimental conditions. The new insight obtained with the present trials are useful for the classical breeding of resistant varieties.