Genetic Analysis and Gene Mapping of Light Brown Spotted Leaf Mutant in Rice

A light brown spotted-leaf mutant of rice was isolated from an ethane methyl sulfonate (EMS)-induced IR64 mutant bank. The mutant, designated as lbsl1 (light brown spotted-leaf 1), displayed light brown spot in the whole growth period from the first leaf to the flag leaf under natural summer field conditions. Agronomic traits including plant height, growth duration, number of filled grains per panicle, seed-setting rate and 1000-grain weight of the mutant were significantly affected. Genetic analysis showed that the mutation was controlled by a single recessive gene, tentatively named lbsl1(t), which was mapped to the short arm of chromosome 6. By developing simple sequence repeat (SSR) markers, the gene was finally delimited to an interval of 130 kb between markers RM586 and RM588. The lbsl1(t) gene is likely a novel rice spotted-leaf gene since no other similar genes have been identified near the chromosomal region. The genetic data and recombination populations provided will facilitate further fine-mapping and cloning of the gene.