《植物生理学报》 2017, 53(2): 209-218

水稻脆秆突变体bc-wy7的鉴定与基因定位

许作鹏^1,2,*, 李善策^2,*, 张冬梅², 仲崇元¹, 张丽佳¹, 朱奕雯¹, 刘巧泉^1,**

¹扬州大学农学院植物功能基因组学教育部重点实验室/江苏省粮食作物现代产业技术协同创新中心, 江苏扬州225009; ²中国科学院遗传与发育生物学研究所植物基因组学国家重点实验室, 北京100101

通信作者：许作鹏；E-mail: qqliu@yzu.edu.cn

摘　要：

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⁶⁰Co-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。

关键词：水稻; 脆秆突变体bc-wy7; BC3基因; 遗传分析; 基因定位

收稿：2016-11-28   修定：2017-01-11

资助：国家重点基础研究发展计划(“973”) (2013CBA01402)和江苏高校品牌专业建设工程(PPZY2015A060)。

Identification and gene cloning of the brittle culm mutant bc-wy7 in rice

XU Zuo-Peng^1,2,*, LI Shan-Ce^2,*, ZHANG Dong-Mei², ZHONG Chong-Yuan¹, ZHANG Li-Jia¹, ZHU Yi-Wen¹, LIU Qiao-Quan^1,**

¹Key Laboratory of Plant Functional Genomics of Ministry of Education / Co-Innovation Center for Modern Production Technology of Grain Crops, Agriculture College, Yangzhou University, Yangzhou, Jiangsu 225009, China; ²State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China

Corresponding author: XU Zuo-Peng; E-mail: qqliu@yzu.edu.cn

Abstract:

Brittle culm is an ideal material for researching of genetics for culm strength. In this study, the mutant bc-wy7 (brittle culm from ‘Wuyunjing7’) exhibited brittle culm, leaf sheath and leaf, was obtained from the japonica variety ‘Wuyunjing7’ (wy7) after ⁶⁰Co-γ induced mutagens. Compared with its wild type (WT), the plant height, panicle length and grain number of panicle of bc-wy7 showed significant decreased, and the heading date appeared significant delayed. It was also showed that there were significant difference in cell wall composition between WT and mutant. The cellulose and glucose content decreased significantly in the culm of mutant, but the content of xylose and arabinose increased significantly. Besides the number of sclerenchyma cell layers and their cell wall thickness were both decreased in culm of the mutant, the number of parenchymal cell increased in the bc-wy7. Genetic analysis implied that the brittle trait in bc-wy7 was controlled by one single recessive nuclear gene. Ultimately, the mutated locus was delimited to ~180 kb genomic region on chromosome 2 between the molecular markers S2-52 and S2-56. In the mapped region, there is a cloned gene named Brittle Culm 3 (BC3) that can cause the brittle phenotype appeared when that gene was mutated, and the bc-wy7 might be allelic to BC3. We further sequenced the allele of BC3 in WT and mutant, and the results showed that there were two nucleotides deletion at the 9^th exon in the mutant, resulted in a frame shift and premature termination of translation. Meanwhile, the data from real-time RT-PCR indicated that there was significant decrease in the expression of BC3 gene in culm and leaf of the mutant. Taken together, we can confirm that bc-wy7 mapped in this study is allelic to BC3 gene.

Key words: Oryza sativa; brittle culm mutant bc-wy7; BC3 gene; genetics analysis; gene mapping