Comparative Mapping Suggests Repeated Selection of the Same Quantitative Trait Locus for High Leaf Photosynthesis Rate in Rice High-Yield Breeding Programs

摘要

Rece (Oryza sativa L.) yield is determined by the relationship between sink, source, and plant architecture. 'Takanari', a high-yielding rice variety descended from 'IR8' and Tongil'. shows a semidwarf plant stature and has a large sink size and highphotosynthesis rate. Previ-ous studies have revealed that alleles of semi-dwarf1 (sd1) and GRAIN NUMBER1A (GN1A), which confer a semidwarf plant type and large panicles, respectively, have been selected repeatedly in breeding programs during the processof breeding for high yield. Until now. however, no genetic factors related to photosynthesis have been identified as having been Selected in breeding programs. In this study, we conducted comparative mapping of quantitative trait loci (QTLs) for photosynthesis-related traits using three F2 populations: 'Koshihikari' x Takanari, Koshihikari x Tongil, and Koshihikari x IR8. Comparison of QTL locations in the three populations revealed a QTL in the same loca-tion on the long arm of chromosome 4 in each one, with the allele for higher photosynthesis-related traits coming from the higher-yielding parent of each population. Further genotypic analysis of the Takanari pedigree revealed the same genotype on the long arm of chromosome 4 in varieties related toIR8 and Takanari. These results suggest that breeders have selected the fevorable allele of the QTL for photosynthesis on chromosome 4 in several breeding programs for high yield.