Fine mapping of , a quantitative trait locus for resistance to , on rice chromosome 1.

Bacterial grain rot (BGR), caused by the bacterial pathogen , is a destructive disease of rice. At anthesis, rice panicles are attacked by the pathogen, and the infection causes unfilled or aborted grains, reducing grain yield and quality. Thus, increasing the level of BGR resistance is an important objective for rice breeding. A quantitative trait locus (QTL) on rice chromosome 1 that controls BGR resistance was previously detected in backcross inbred lines (BILs) derived from a cross between Kele, a resistant traditional lowland cultivar () that originated in India, and Hitomebore, a susceptible modern lowland cultivar () from Japan. Further genetic analyses using a BCF population derived from a cross between a resistant BIL (BCF) and Hitomebore confirmed that a QTL for BGR resistance was located on the long arm of chromosome 1. To define more precisely the chromosomal region underlying this QTL, we identified nine BCF plants in which recombination occurred near the QTL. Substitution mapping using homozygous recombinant and nonrecombinant plants demonstrated that the QTL, here designated as (), was located in a 502-kb interval defined by simple sequence repeat markers RM1216 and RM11727.