USSR5, a japonica rice variety from the former Soviet Union, is an extremely early maturing rice variety. To elucidate the genetic basis for its early heading, genetic analysis was carried out by crossing it with a se...USSR5, a japonica rice variety from the former Soviet Union, is an extremely early maturing rice variety. To elucidate the genetic basis for its early heading, genetic analysis was carried out by crossing it with a set of major gene nearly isogenic lines （NIL） and QTL-isogenic lines. The early heading of USSR5 was attributed to the presence of photoperiod-insensitive alleles at E1 and Se-1 gene, the photoperiod-sensitive inhibitor gene i-Se-1, and the dominant earliness gene Ef-1. Analysis of a backcrossed population （BCIF1） derived from the cross USSR5 x N22 indicated that two quantitative trait loci （QTL） for early heading were located on chromosomes 7 and 8, accounting for 27.4% and 11.2% of the phenotypic variance, respectively, with both early alleles originating from USSRS. From an F2 population of the same cross, early heading QTLs were detected on chromosomes 1, 2, 7, 9, and 10, with individual QTL accounting for between 4.1% and 15.4% of the phenotypic variance. Early heading alleles at four of these five QTLs originated from USSRS. A comparison of chromosomal locations suggests that one of these QTLs may be identical with the known gene Hd4 （E1）. The relationship between the other QTLs and known genes for heading date are not clear. USSR5 is a promising source for propagating earliness for the development of improved early heading rice varieties.展开更多
基金This work was supported by the National Natural Science Foundation of China (No. 30571142), the 948 Project from the Ministry of Agricultue (No. 2004-Z24), Jiangsu Province High Technology Foundation (No. BG2004303), the Key Technology of Agricultural Structural Adjustment (No. 05-01-05B) and PCSIRT.
文摘USSR5, a japonica rice variety from the former Soviet Union, is an extremely early maturing rice variety. To elucidate the genetic basis for its early heading, genetic analysis was carried out by crossing it with a set of major gene nearly isogenic lines （NIL） and QTL-isogenic lines. The early heading of USSR5 was attributed to the presence of photoperiod-insensitive alleles at E1 and Se-1 gene, the photoperiod-sensitive inhibitor gene i-Se-1, and the dominant earliness gene Ef-1. Analysis of a backcrossed population （BCIF1） derived from the cross USSR5 x N22 indicated that two quantitative trait loci （QTL） for early heading were located on chromosomes 7 and 8, accounting for 27.4% and 11.2% of the phenotypic variance, respectively, with both early alleles originating from USSRS. From an F2 population of the same cross, early heading QTLs were detected on chromosomes 1, 2, 7, 9, and 10, with individual QTL accounting for between 4.1% and 15.4% of the phenotypic variance. Early heading alleles at four of these five QTLs originated from USSRS. A comparison of chromosomal locations suggests that one of these QTLs may be identical with the known gene Hd4 （E1）. The relationship between the other QTLs and known genes for heading date are not clear. USSR5 is a promising source for propagating earliness for the development of improved early heading rice varieties.
