Fine mapping and candidate gene prediction of the photoperiod and thermo-sensitive genic male sterile gene pms1(t) in rice.

Pei'ai64S, an indica sterile variety with photoperiod and thermo-sensitive genic male sterile (PTGMS) genes, has been widely exploited for commercial seed production for "two-line" hybrid rice in China. One PTGMS gene from Pei'ai64S, pms1(t), was mapped by a strategy of bulked-extreme and recessive-class approach with simple sequence repeat (SSR) and insert and deletion (In-Del) markers. Using linkage analysis for the F(2) mapping population consisting of 320 completely male sterile individuals derived from a cross between Pei'ai64S and 93-11 (indica restorer) lines, the pms1(t) gene was delimited to the region between the RM21242 (0.2 cM) and YF11 (0.2 cM) markers on the short arm of chromosome 7. The interval containing the pms1(t) locus, which was co-segregated with RM6776, is a 101.1 kb region based on the Nipponbare rice genome. Fourteen predicted loci were found in this region by the Institute for Genomic Research (TIGR) Genomic Annotation. Based on the function of the locus LOC_Os07g12130 by bioinformatics analysis, it is predicted to encode a protein containing a Myb-like DNA-binding domain, and may process the transcript with thermosensory response. The reverse transcription-polymerase chain reaction (RT-PCR) results revealed that the mRNA levels of LOC_Os07g12130 were altered in different photoperiod and temperature treatments. Thus, the LOC_Os07g12130 locus is the most likely candidate gene for pms1(t). These results may facilitate not only using the molecular marker assisted selection of PTGMS genes, but also cloning of the pms1(t) gene itself.