Mapping of a new thermo-sensitive leaf-color mutant gene in rice (Oryza sativa L.)

A thermo-sensitive leaf-color mutant, MR20, was discovered in progeny of a japonica variety, Jiahua No.1, induced by 60Co γ-rays irradiation. Under the conditions of low temperature (20 degree C ), the leaf-color of the mutant at seedling stage was yellow and tuned into green with the increase of temperature and its critical temperature was about 22.5 degree C. In addition, the significant difference of the chlorophyll contents at two temperatures (20 degree C and 32 degree C) was observed showing that MR20 was a thermo-sensitive chlorophyll-deficit mutant at the seedling stage. Genetic analysis revealed that the character of thermo-sensitive chlorophyll-deficit was controlled by a single recessive nuclear gene, tentatively designated as tsc (t). The F2 population derived from the cross MR20 x 9311 was as materials, and SSR markers was used, the tsc (t) gene was roughly mapped at between RM231 and RM14407 molecular markers on the short arm of chromosome 3 with the genetic distance of 1.5 cM and 0.5 cM, respectively. With larger F2 mapping population, the tsc (t) gene was narrowed to 440kb between MM0541 and RM14407 molecular markers. (authors)