Segregation distortion in common wheat of a segment ofThinopyrum intermediumchromosome 7E carryingBdv3and development of aBdv3marker

Yellow dwarf (YD) disease is one of the most destructive diseases of cereals worldwide. Wheat (Triticum aestivum L.)-Thinopyrum intermedium 7E(7D) substitution line P29 carries resistance to YD, known as Bdv3, that originates on the long arm of chromosome 7E of Th. intermedium, and the resistance was introgressed into wheat chromosome 7D as T7DS.7DL-7EL in the translocation lines P961341 and P98134. Until now, quantification of YD viruses in cereal crops was usually done by enzyme-linked immunosorbent assay (ELISA), which is time consuming and laborious. To facilitate this analysis, SSR-Bdv3, a diagnostic molecular marker, was developed in this study. The transmission of the Th. intermedium segment with Bdv3 was investigated using the SSR-Bdv3 marker and ELISA in F 2 and testcross progeny derived by crossing two wheat-Th. intermedium translocation lines to four common wheat cultivars. A Th. intermedium chromosome 7E segment in the translocation line P98134 was preferentially transmitted through male gametes in all of its crosses with the four wheat cultivars. However, the transmission frequency of the Th. intermedium 7E segment in another wheat-Th. intermedium translocation line, P961341, varied in different genetic backgrounds. The F2 populations from reciprocal crosses of Chinese Spring and P961341 showed good fits to the expected ratio of 1: 2: 1. In this study, male preferential transmission for either chromosome 7E or chromosome 7D was observed in the progeny derived by crossing P961341 to other wheat cultivars.