Abstract：The objective of this study is to develop more molecular markers for construction of high density genetic map of the leaf rust resistance gene Lr45 in wheat (Triticum aestivum L.). Twenty-six pairs of expressed sequence tag(EST) primers located on the short arm of wheat chromosome 2A in combination with 4 kinds of restriction enzyme, resulting in a total of 104 pairs of EST-CAPS(expressed sequence tags-cleaved amplified polymorphic sequences) markers were used to analyze the polymorphism between TcLr45 and Thatcher. The EST primers BE426158 and BE442876 expressed polymorphsim of the PCR products between TcLr45(resistant leaf rust parent) and Thatcher(susceptible leaf rust parent) with the polymorphism rate of 7.7%. Four of 104 primers/restriction enzyme combinations (3.8%), CD454036 /MspⅠ, CD454036 /HaeⅢ, BE406923 /MspⅠ and BE425962 / RsaⅠ, were polymorphic between Thatcher and TcLr45. In addition, a pair of primers designed based on the sequence of band amplified with BE426158 in TcLr45 and converted successfully to a stable STS(sequence tagged site) marker, LR45-1. The linkage distance of the LR45-1 with Lr45 was 8.2 cM based on the data of a F2 population derived from TcLr45×Thatcher. The specificity and stability were validated by testing the wheat leaf rust resistance near isogenic lines and rye(Secale cereale) varieties. The results described above indicate that the EST-CAPS markers can be used in analysising of polymorphisms and development of molecular markers in wheat leaf rust resistance genes.
