Characterization and Gene Mapping of a Dominant Brittle Culm Mutant Bc18 in Rice (Oryza sativa L.)
A brittle culm mutant was obtained from the F2 population of three-way cross Ⅱ-32B//Xieqingzao B/Dular and named as Brittle culm 18 (Bc18 )according to its phenotypes.Each part of plant showed brittleness during the whole growth period.In order to identify the mutant,near isogenic line populations of Zhongcui B and Zhong 9B were created with Bc18 mutant as the donor of brittle gene and Zhong 9B,a normal culm-strength variety,as the receptor and recurrent parent.Compared with wild type,Bc18 significantly declined by 70.70% and 47.16% in mechanical strength of culm and leaves,respectively.No significant differences were found in terms of growth duration,plant height,panicle number per plant,spikelet number per panicle,seed setting rate and 1000-grain weight.Cell wall components analyses showed that cellulose content and lignin content in Bc18 had no significant difference as compared with those of wild type,while hemicellulose content in culm and leaf dramatically increased by 31.84% and 17.35%, respectively.Genetic analyses of six F2 and twelve BC1 F1 backcross populations revealed that the phenotype of Bc18 was controlled by a single dominant gene.Bc18/02428 and Bc18/9311 F2 populations were developed for Bc18 gene mapping.By means of map-based cloning technology,with some SSR markers published online and new designed InDel markers,Bc18 was localized between InDel marker PBC22 and PBC33 at a physical distance of about 154 kb on the long arm of chromosome 1 .This work laid the foundation for cloning Bc18 gene in the future.
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