水稻脆秆突变体bc-s1的表型分析和基因定位

茎秆机械强度影响植株抗倒伏能力, 是备受关注的重要农艺性状之一。与野生型相比, 水稻(Oryza sativa)脆秆隐性突变体bc-s1茎秆抗折力和抗张力分别降低31.1%和67.2%, 茎秆纤维素和木质素含量分别降低24.97%和增高38.82%。细胞学分析显示, bc-s1茎秆厚壁细胞发生不规则变化, 次生壁增厚受阻。通过图位克隆和测序分析, 初步确定bc-s1突变体中纤维素合成酶催化亚基Os09g25490/OsCesA9基因第1外显子的第28个碱基G突变为A。该等位突变体的获得为进一步揭示OsCesA9调控细胞壁建成的生物学功能提供了新的研究材料。

Characterisation and Gene Mapping of a Brittle Culm Mutant bc-s1 in Rice

The mechanical strength of rice stem is an important agronomic trait that affects crop lodging. In this study, a brittle culm mutant, bc-s1, was identified from the rice mutant library. The mutant showed inherited traits of brittleness from bolting to mature stage. Meanwhile, the leaf, leaf sheath, culm, node and seed shell of the mutant showed brittleness during the mature stage. Compared with breaking and elongation force in the wild type, that in bc-s1 culms decreased 31.1% and 67.2%, respectively. Besides showing irregular shape of sclerenchyma cells, in bc-s1, cellulose and lignin content in culm decreased 24.97% and increased 38.82%, respectively. The BC-S1 gene was mapped on chromosome 9 between InDel markers Ha6 and Ha9 within 101 kb physical distance. According to sequencing results for bc-s1, a candidate open reading frame (Os09g25490/OsCesA9), which encodes a cellulose synthase catalytic subunit (CesA), showed a point mutation at the 28^th base of first extron, changing GGG to AGG and causing the substitution at the 10th amino acid residue from glycine to arginine. Therefore, bc-s1 is a new allele of OsCesA9 and provides a new material for uncovering the biological function of OsCesA9 in rice cell-wall biosynthesis.