PROGRESSES IN MAP-BASED CLONING OF AGRICULTURALLY IMPORTANT GENES IN RICE

National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China

We have recently identified and mapped a large number of agriculturally important genes in rice using molecular markers, including genes for disease resistance, grain quality, male sterility, wide compatibility and agronomic performance. We are currently cloning several of the genes following a map-based cloning approach. A BAC library consisting of approximately 26,000 clones with the average insert size ca. 150 kb was constructed to the cultivar Minghui 63, which represented a capacity of nine-genome equivalent. A cosmid library consisting of 45,000 clones with the average insert size ca. 40 kb was also constructed to the same cultivar, representing a capacity of 4.2-genome equivalent. We have also been constructing BAC libraries with insert size in the range of 40-50 kb using varieties carrying various targeted genes. Chromosomal walking has been conducted for several genomic regions. We are now at the stage of near completion of contig maps for a gene for photoperiod sensitive male sterility (pms1), a gene for wide compatibility (S5) and a gene for bacterial blight resistance (Xa22). The progresses will be presented in details in the conference.