Development of TGMS lines and two-line rice hybrids through a shuttle breeding program between IRRI and China

摘要

Based on the discovery of photoperiod-sensitive genie male sterile (PGMS) rice mutant Nongken 58S (Shi 1981), rice scientists in China began work on the two-line system of hybrid rice breeding in the early 1980s, Subsequently, some thermosensitive genie male sterile (TGMS) rice mutants, such as Annong S-l and 5460S, were developed in 1988 through screening of breeding materials and radiation, respectively (Lu et al 1998). The two-line system was established in China by using PGMS and TGMS lines. Thismethod was considered more efficient than the three-line system in exploiting het-erosis to increase yield. More than 10 environment-sensitive genie male sterile lines have been used to breed more than 32 commercial two-line hybrids in China, The area planted to two-line hybrids, which gave 5% higher yield than three-line hybrids, was 2 million ha in 2002. In the tropics, TGMS lines may be more useful than PGMS lines because of the significant temperature variation among seasons. A shuttle breeding program between China and IRRI was conducted in the past 5 years to develop and evaluate TGMS lines and two-line rice hybrids. Several useful TGMS lines have so far been developed.