RESUMEN
To understand the genetic basis of yield-related traits of rice, we developed 39 chromosome segment substitution lines (CSSLs) from a cross between an average-yielding japonica cultivar, Sasanishiki, as the recurrent parent and a high-yielding indica cultivar, Habataki, as the donor. Five morphological components of panicle architecture in the CSSLs were evaluated in 2 years, and 38 quantitative trait loci (QTLs) distributed on 11 chromosomes were detected. The additive effect of each QTL was relatively small, suggesting that none of the QTLs could explain much of the phenotypic difference in sink size between Sasanishiki and Habataki. We developed nearly isogenic lines for two major QTLs, qSBN1 (for secondary branch number on chromosome 1) and qPBN6 (for primary branch number on chromosome 6), and a line containing both. Phenotypic analysis of these lines revealed that qSBN1 and qPBN6 contributed independently to sink size and that the combined line produced more spikelets. This suggests that the cumulative effects of QTLs distributed throughout the genome form the major genetic basis of panicle architecture in rice.
Asunto(s)
Cromosomas de las Plantas/genética , Oryza/genética , Sitios de Carácter Cuantitativo , Carácter Cuantitativo Heredable , Mapeo Cromosómico , Cruzamientos Genéticos , Oryza/metabolismo , FenotipoRESUMEN
Loss of seed shattering was a key event in the domestication of major cereals. We revealed that the qSH1 gene, a major quantitative trait locus of seed shattering in rice, encodes a BEL1-type homeobox gene and demonstrated that a single-nucleotide polymorphism (SNP) in the 5' regulatory region of the qSH1 gene caused loss of seed shattering owing to the absence of abscission layer formation. Haplotype analysis and association analysis in various rice collections revealed that the SNP was highly associated with shattering among japonica subspecies of rice, implying that it was a target of artificial selection during rice domestication.