Identification of quantitative trait locus and epistatic interaction for degenerated spikelets on the top of panicle in rice: QTL and interaction for spikelet degeneration

P>The phenomenon of degenerated spikelets is very common in cereal crops, and considered as a serious physiological defect to grain production. However, little is known about the genetic base of the spikelet degeneration in rice. To identify genetic factors conferring spikelet degeneration in rice, a line showing severe degenerated spikelets on the top of panicle was selected from a set of chromosomal segment substitution lines that derived from a cross of the sequenced japonica variety 'Nipponbare' and the indica variety '9311'. Using its derived progeny, two quantitative trait loci (QTL) for the degenerated spikelets were identified on chromosomes 3 and 9. The one on chromosome 3 was confirmed in an about 600-kb physical interval, and had an epistatic interaction with the other QTL on chromosome 9. The QTL region on chromosome 3 was also found conferring primary panicle length, heading date, the number of primary branches and second branches simultaneously. These results would be helpful in understanding the genetic control of spikelet degeneration on the top of panicle in rice.