Genetics, fertility behaviour and molecular marker analysis of a new TGMS line, TS6, in rice

The thermosensitive genic male sterility (TGMS) system has great potential for revolutionizing hybrid rice production through simple, less expensive and more efficient seed production technology. For the successful utilization of this novel male sterility system, knowledge of the breeding and fertility behaviour of a TGMS line is essential. In this study, the fertility transformation behaviour, the critical fertility and sterility temperatures and the mode of inheritance of male sterility were studied for a new TGMS line, TS6, identified at Tamil Nadu Agricultural University, Coimbatore, India. The pollen and spikelet fertilities recorded on plants raised at fortnightly intervals revealed that this line was completely sterile for 78 consecutive days (35/22 to 32/23°C, maximum/minimum temperatures) and reverted to fertile when the temperature was 30/18°C. It remained fertile continuously for 69 days and the maximum pollen and spikelet fertilities recorded were 75 and 70%, respectively. The fertility was highly influenced by daily maximum temperature followed by average and minimum temperatures. It was not influenced by relative humidity, sunshine hours or photoperiod. The critical temperature inducing sterility and fertility was 26.7 and 25.5°C, respectively. The male sterility in TS6 was inherited as a monogenic recessive in the F₂ and BC₁ populations of TS6 × MRST9 as well as TS6 × IR68281B. Using bulked segregant analysis on an F₂ population of TS6 × MRST9, an RAPD marker, OPC05₂₉₆₂, was identified to be associated with TGMS in TS6.