Abstract: 【Objective】 The objective of this study is to conduct genetic analysis and molecular mapping of lesion mimic mutant C23 in rice. 【Method】 A lesion mimic mutant was isolated by chemical mutagen EMS. The phenotypes and main agronomic traits of the mutant were observed. Histochemical analysis was used to detect the cell death type. Genetic mapping of the mutant gene was conducted by using molecular marker and F2 mapping population of C23/Zhefu802. 【Result】 The lesion first appeared on leaves as straw-yellow and approximate circular spot at 3-leaf stage. With the growth of the mutant plant, the number of the lesion increased, its area gradually expanded and coalesced into larger lesion with dry yellow center and orangish brown edge. The lesion almost occupied the whole plant till the maturaty stage. The trypan blue staining indicated that the cell death of C23 probably belonged to the programmed cell death. Compared with its wild-type parent, the plant height decreased, the number of productive panicles per plant and the number of spikelets per panicle reduced, 1000-grain-weight and seed setting rate dropped. Genetic analysis showed that the lesion mimic character of C23 was controlled by one pair of recessive nuclear genes. This gene is located on rice chromosome 12, nearby centromere, between SSR marker RM101 and InDel marker Ch12-112. The genetic distances from the target gene to two markers were 0.36 and 0.73cM, respectively. At the same time, the mutant gene co-segregated with four InDel markers, Ch12-91, Ch12-92, Ch12-95 and Ch12-104. 【Conclusion】 It was considered that the mutant gene of C23 is located on nearby of spl1 gene loci, but the mutant C23 and spl1 have obviously difference in the lesion mimic phenotypes.

Key words: rice (Oryza sativa L.), lesion mimic gene, genetic analysis, molecular mapping