Efficient marker-assisted screening of structural changes involving Haynaldia villosa chromosome 6V using a double-distal-marker strategy

Wild relatives of wheat possess many agronomic traits important to wheat improvement. Wheat–alien translocation and deletion lines are important genetic stocks in wheat breeding or physical mapping of important alien genes. However, screening for chromosomal structural changes by conventional cytogenetic analyses is time-consuming work. It is necessary to develop an efficient method of finding alien chromosomal structural changes. In this research, two amplicon markers, 6VS- ₃₈₁ and 6VL- ₃₅₈ , specific to the distal regions of the short and long arms, respectively, of Haynaldia villosa chromosome 6V, were developed based on the expressed sequence tags located on the distal regions of wheat group 6. Marker-assisted screening work was then carried out in two individual radiation-induced populations. The first contained 365 plants involving 43 M₁:₂families derived from a pollen irradiation treatment of a wheat–H. villosa monosomic 6V addition line. The other was a M₁population containing 100 plants derived from an irradiation treatment of a wheat–H. villosa disomic 6V(6A) substitution line. The female parent in both treatments was a common wheat cultivar Chinese Spring. Those plants marked by a single positive distal marker were considered to be putative structural changes of 6V. After cytogenetic analysis, a total of 20 structure-changed chromosomes were identified, comprising 12 whole-arm translocations, four terminal translocations, one 6VL terminal deletion, one translocation deletion, and two intercalary translocations. The double-distal-marker strategy proposed in this study gives an efficient model for finding structural aberrations involving a specific alien chromosome.