QTL Mapping of Spikelet Number in Rice(Oryza sativa L.).

We conducted a QTL (quantitative trait locus) analysis to identify the genetic characteristics of traits related to yield in rice, using 191 recombinant inbred (R.I.) lines derived from Milyang 23/Akihikari. We found that a QTL at the end of chromosome 1 clearly contributed to the spikelet number per panicle and spikelet number per unit area. One of the 191 R.I. lines, H8, showed a segregation of the spikelet number per panicle or per unit area in 1998. H8 was also heterozygous near the QTL. We determined the spikelet number per unit area and panicle number for 74 individual plants of line H8. An RFLP linkage map was constructed using data for heterozygous regions on chromosome 1 and other chromosomes. For the QTL analysis, this linkage map and the spikelet number data were used. The results showed that a QTL explaining 38.7% of the variance of the increased spikelet number per panicle was located neaer the RFLP marker R3192, at the end of the short arm of chromosome 1. This QTL was considered to be very effective in increasing the spikelet number per panicle; it originated from an indica variety, Milyang 23.