TAGGING AND MAPPING THE THERMOSENSITIVE GENIC MALE-STERILE GENE IN RICE (ORYZA-SATIVA L) WITH MOLECULAR MARKERS

The thermo-sensititve genic male-sterile (TGMS) gene in rice can alter fertility in response to temperature and is useful in the two-line sy stem of hybrid rice production. However, little is known about the TGM S gene at the molecular level. The objective of this study was to iden tify molecular markers tightly linked with the TGMS gene and to map th e gene onto a specific rice chromosome. Bulked segregant analysis of a n F-2 population from 5460s (a TGMS mutant line) x 'Hong Wan 52' was u sed to identify RAPD markers linked to the rice TGMS gene. Four hundre d RAPD primers were screened for polymorphisms between the parents and between two bulks representing fertile and sterile plants; of these, 4 primers produced polymorphic products. Most of the polymorphic fragm ents contained repetitive sequences. Only one single-copy sequence fra gment was found, a 1.2-kb fragment amplified by primer OPB-19 and subs equently named TGMS1.2. TGMS1.2 was mapped on chromosome 8 with a RIL population and confirmed by remapping with a DHL population. Segregati on analysis using TGMS1.2 as a probe indicated that TGMS1.2 both conse gregated and was lined with the TGMS gene in this population. It is lo cated about 6.7 cM from the TGMS gene. As TGMS1.2 is linked to the TGM S gene, the TGMS gene must be located on chromosome 8.