A genetic analysis of segregation distortion revealed by molecular markers in Lophopyrum ponticum chromosome 7E

Segregation distortion can be defined as deviations from normal Mendelian segregation (Sandler et al. 1958). It is a common phenomenon found in most genetic mapping studies in many species (Faris et al. 1998). Lophopyrum ponticum (also syn. Agropyron elongatum (Host) Beau.) has been one of the most important perennial Triticeae germplasm sources for wheat improvement (Oliver et al. 2006). Chromosome 7E of L. ponticum is crucial because it is the carrier of a number of elite agronomic traits (Zhang et al. 2011). However, there is still no report about molecular markers showing segregation distortion region of L. ponticum chromosome 7E. Segregation distortion caused by preferential transmission may be affected by genetic background. Kong et al. (2008) reported that a segment of the Thinopyrum intermedium chromosome 7E present in the translocation line P98134 was preferentially transmitted through male gametes under different genetic background conditions. However, the transmission frequency of T. intermedium 7E segment present in another wheat T. intermedium translocation line, P961341, varied with different genetic backgrounds. Similarly, studies on the translocations involving T. ponticum chromosome 7el1 indicated that Thinopyrum chromosome 7el1 was transmitted normally in Thatcher and China Spring wheat backgrounds (McIntosh et al. 1976). However, high levels of distortion were observed when chromosome 7el1 was transferred in other genetic backgrounds (McIntosh et al. 1995). Both 7el1 and 7el2, are gametocidal chromosomes (KibirigeSebunya and Knott 1983; Prins et al. 1996). Gametocidal chromosomes cause abortion of gametes lacking the gametocidal chromosome, which results in partial sterility and exclusive transmission of these chromosomes (Endo 1990).