Grain appearance is one of the most important traits along with yield and palatability in rice production and breeding programs. To identify the chromosomal regions controlling grain appearance, we performed quantitative trait locus (QTL) analysis using chromosome segment substitution lines (CSSLs) derived from a cross between an indica cultivar, Kasalath (donor), and a japonica cultivar, Koshihikari (recurrent). The grain appearances of CSSLs were classified into six categories: perfect grains, immature white grains subclassified as white-back kernels, basal-white kernels, white berry kernels, milk-white kernels, and white core kernels. The ratios of kernels were used as traits in QTL identification. It was suggested that 12 chromosomal regions of chromosomes 1 (two regions), 2 (two regions), 5, 6, 7, 8, 9, 10, 11, and 12 were involved in QTLs for grain appearance. The total percentage of white-back and basal-white kernels was decreased by the substitution of the Kasalath chromosomal regions of chromosomes 2, 9, 11, and 12, but was increased by five regions of chromosomes 2, 5, 6, 8, and 10. The Kasalath alleles in one region of chromosome 1 and two regions of chromosomes 1 and 7 increased the proportion of white berry and milk-white kernels individually. Furthermore, we performed QTL mapping for grain appearance to validate the QTLs of chromosomes 1, 2, 5, and 12 using four F₂ populations derived from a cross between CSSLs and Koshihikari. As a result, it was confirmed that four QTLs (RM3865 or RM3703 (chr2), RM1208 (chr12), S1946 (chr5), and RM8084 (chr12)) were involved in the gene causing phenotypic differences between the CSSLs and Koshihikari.

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The genetic analysis of scald (Rhynchosporium secalis (Oud.) Davis) resistance of barley plants was conducted among progeny lines derived from crosses that include Brier as a donor parent for resistance. Phenotypic and genotypic correlations between the severity of infection and growth characteristics, yield, and pearled-grain quality were calculated for F₂ generations to clarify problems regarding introducing resistance genes of Brier into Japanese varieties. Barley plants in the early tilling stage in a field were infected with scald by distributing infected barley seedlings which had been inoculated in a greenhouse by fungus strain NB1-1-1, classified as a dominant race in the Hokuriku district. Genetic segregations of resistance were investigated using progeny lines evaluated on a scale of zero to five for the severity of infection at 30 days after heading in a field. The resistance to scald seemed to be controlled by three recessive genes which were highly heritable, suggesting that it is relatively straightforward to select plants with high-level resistance in an early hybrid generation. However, heritability for resistance was low in environments unsuitable for scald infection and development. Inoculation tests must be conducted for several years to evaluate the resistance of plants. In the present experiments, a small number of progeny with resistance and marked quality was obtained by a single cross with Brier. Therefore, successive crosses among favorable progeny lines appear promising. It is necessary to choose parents to cross with Brier carefully, because Brier's resistance to scald may be associated with undesirable traits such as late maturity and low pearled-grain whiteness.

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