脆秆突变体是研究植物茎秆机械强度遗传机制的理想材料。本研究利用~(60)Co-γ诱变粳稻品种‘武运粳7号’(‘Wuyunjing7’,wy7),在其后代中选到1份叶片、叶鞘、茎秆等组织易折断的脆性突变体,命名为bc-wy7(brittle culm from‘Wuyunjing7’)。与野生型相比,突变体bc-wy7在全生育期期间均表现出脆性,其株高变矮、穗长变短、穗粒数减少、生育期推迟,并出现包颈的表型。茎秆细胞壁糖组分分析表明,突变体bc-wy7茎秆细胞壁中纤维素和葡萄糖含量显著降低,木糖及阿拉伯糖的含量显著增加,其他糖成分含量与野生型无显著差异。荧光显微镜观察表明,突变体bc-wy7茎秆表皮层下方厚壁组织及厚壁细胞细胞壁变薄,薄壁细胞呈现变小的趋势,但排列更紧密。遗传分析结果表明,突变体bc-wy7的脆性性状由1对隐性核基因控制,利用图位克隆技术将该基因定位于第2染色体分子标记S2-52与S2-56间180 kb的物理区段内,该区段内包含1个已克隆的与茎秆机械强度相关的基因Brittle Culm 3(BC3)。测序结果表明,突变体bc-wy7中BC3基因第9外显子处有2个碱基缺失,造成移码突变使翻译提前终止;定量RT-PCR结果表明,脆秆突变体bc-wy7茎秆和叶片中BC3基因的表达量均降低。据此推断定位的脆秆基因bc-wy7为BC3基因的等位基因。 Embarrassed mutant is an ideal material for studying the genetic mechanism of mechanical strength of plant stem. In this study, a japonica rice cultivar ’Wuyunjing7’ (wy7) was mutated with ~ (60) Co-γ, and one fragile mutant was selected from its offspring, which was easily broken by leaves, leaf sheaths and stems , Named bc-wy7 (brittle culm from ’Wuyunjing7’). Compared with the wild type, the mutant bc-wy7 showed brittleness during the whole growth period, its plant height was shortened, the spike length was short, the number of grains per spike was reduced, the growth period was postponed, and the phenotype of the neck was appeared. The analysis of sugar content in stem cell wall showed that the content of cellulose and glucose in the cell wall of mutant bc-wy7 decreased significantly, the content of xylose and arabinose increased significantly, while the content of other sugar components had no significant difference with the wild type. Fluorescence microscopy showed that the thick walled cells and the thick walled cells under the bc-wy7 stalk were thinner and the parenchyma cells tended to become smaller, but arranged more closely. The results of genetic analysis indicated that the brittle trait of mutant bc-wy7 was controlled by a pair of recessive nuclear genes. Using the map-based cloning technique, the gene was mapped to a 180 kb physical region between S2-52 and S2-56 on chromosome 2 Within this segment was a Brittle Culm 3 (BC3) gene that was cloned to correlate with the mechanical strength of the stalk. The results of sequencing showed that there was a 2-base deletion at BC9 gene in the mutant bc-wy7, which caused the frameshift mutation to terminate the translation prematurely. The quantitative RT-PCR results showed that the bc-wy7 stalk And BC3 gene expression in leaves were reduced. Based on this, it was inferred that the locus of brittle culm gene bc-wy7 is the allele of BC3 gene.