A thermo-sensitve seedling-colour mutant 7436S was detected in the field from a breeding nursery in China, in 1991. The experiments were conducted at artificially controlled temperatures (23.1℃,26.1℃，30.1℃) in growth chambers. The results showed that the seedling colour of the mutant 7436S was white (23.1℃), light yellow (26.1℃) and normal green (30.1℃) at 10 days after sowing and yellwish green (23.1℃) and normal green (26.1℃，30.1℃) at 20 days after sowing, respectively. It was concluded that its thermo-sensitivity decreased gradually with the increase of the seedling age. In addition, its thermo-sensitivity for seedling colour was oriented, as white seedlings turned green at high temperatures, but not in the opposite direction. The segregation ratios in the F2 populations showed that a recessive nuclear gene (tentatively designated as tsc-1) controlled the thermo-sensitive seedling-colour character. Based on genetic linkage and the recombination value (34.1%) between the tsc-1 gene and short panicle morphological marker(sp) gene in the F2 generation, the results indicated that the tsc-1 gene was located on chromosome 11.

Knowledge of the genetics of leaf chlorophyll content (LCC) at tillering and heading stages should help develop rice varieties with high photosynthetic ability. In this study, 182 backcross-recombinant inbred lines (BIL), derived from Koshihikari (japonica)/Kasalath (indica)//Koshihikari, were used to identify quantitative trait loci (QTL) for LCC at the tillering and heading stages of rice. Continuous variation and transgressive segregation for LCC were observed in the BIL population, indicating that LCC was a quantitatively inherited trait. Seven QTL for LCC were identified and mapped to chromosomes 1 (two QTL), 2, 3, 4, 6, and 8, which individually accounted for 5.1 to 14.8% of the total phenotypic variation. Three QTL (qLCC-1-1, qLCC-1-2 and qLCC-4) were common between the tillering and heading stages. The alleles at four QTL (qLCC-1-1, qLCC-1-2, qLCC-2, and qLCC-8) from Koshihikari and the alleles at the other three QTL (qLCC-3, qLCC-4 and qLCC-6) from Kasalath increased LCC. The tightly linked molecular markers flanking the QTL detected in this study should be useful in improving photosynthetic ability in rice.

Phenolic acids are secondary metabolic organic compounds produced by plants and often are mentioned as allelochemicals. This study was conducted to determine the genetic basis controlling the ferulic acid content of rice straw in a recombinant inbred (RI) population derived from a cross between a japonica variety, Asominori, with a higher content of ferulic acid, and an indica variety, IR24, with a lower content, using 289 RFLP markers. Continuous distributions and transgressive segregations of ferulic acid content were observed in the RI population, which showed that ferulic acid content in rice straw was quantitatively inherited. Single marker analysis and composite interval mapping identified three quantitative trait loci (QTLs) for ferulic acid content with LOD values of 2.03 (chromosome 3), 3.16 (chromosome 6), and 3.06 (chromosome 7); all three had increased additive effects (13.5, 18.3, and 18.1 μg g−1) from the Asominori parent and accounted for 5.5, 16.9, and 12.8% of total phenotypic variation, respectively. This is the first report on the identification of QTLs associated with ferulic acid and their chromosomal localization on the molecular map of rice. The tightly linked molecular markers that flank the QTLs might be useful in breeding and selection of varieties with higher phenolic acid content.