Systemic development of wheat-Thinopyrum elongatum translocation lines and their deployment in wheat breeding for Fusarium head blight resistance.

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is one of the most destructive diseases of wheat around the world. FHB causes significant yield losses and reduces grain quality. The lack of resistance resources is a major bottleneck for wheat FHB resistance breeding. As a wheat relative, Thinopyrum elongatum contains many genes that can be used for wheat improvement. Although a novel gene Fhb-7EL was mapped on the chromosome 7EL of Th. elongatum, no successful example of transferring the FHB-resistance gene into commercial wheat varieties was reported. In this study, we developed 836 wheat-Th. elongatum translocation lines of various types by irradiating the pollen of the wheat-Th. elongatum addition line CS-7EL at the flowering stage, among which 81 were identified as resistant to FHB. By backcrossing the FHB-resistance lines with the main cultivar Jimai 22, three wheat-Th. elongatum translocation lines, Zhongke 1878, Zhongke 166, and Zhongke 545, were successfully applied into wheat breeding without yield penalty. Combining karyotype and phenotype analysis, we mapped the Fhb-7EL gene to the distal end of chromosome 7EL. Five molecular markers linked with the FHB-resistance interval were developed, which facilitates molecular marker-assisted breeding. Altogether, we successfully applied the alien chromatin with FHB resistance from Th. elongatum into wheat breeding without yield penalty. These newly developed FHB-resistance wheat-Th. elongatum translocation lines, Zhongke 1878, Zhongke 166, and Zhongke 545, can be used as novel resistance resources for wheat breeding.