水稻窄卷叶突变体nrl7的鉴定与基因定位

叶片的形态是理想株型的重要性状, 叶片适度卷曲能提高水稻(Oryza sativa)群体的光能利用率, 研究控制水稻叶片形态的相关基因能够进一步丰富株型理论。该研究在粳稻品系C275的群体中发现了1株自然变异的窄卷叶突变体nrl7(narrow rolled leaf 7)。与野生型相比, 突变体的叶片变窄且向内卷曲; 该突变体叶片连接中脉的泡状细胞严重变形, 中脉与小叶脉之间的维管束数量均减少至1个。此外, 突变体nrl7的株高、实粒数和实粒重均降低或减少, 分别为野生型的88.46%、69.77%和68.98%, 差异达极显著水平。叶片卷曲导致单叶光合速率减弱, 与野生型相比, 突变体的光合速率降低了17%, 达极显著水平。突变体nrI7叶片的气孔导度、胞间CO₂浓度和蒸腾速率则与野生型相比无明显变化。利用图位克隆的方法将目的基因定位于水稻第3染色体短臂上的分子标记RM5444和MM1300之间, 物理距离约为185.14 kb。研究结果为该基因的克隆和进一步的功能分析奠定了基础。

Identification and Gene Mapping of the nrl7 Mutant in Rice

Leaf morphology is an important trait of ideotype breeding; moderate rolling of leaves can enhance light-use efficiency. Study of genes that control leaf morphology can enrich the theory of ideal plant architecture in rice. We found a novel spontaneous mutant nrl7 with narrow rolled leaves in the japonica C275 population that can be stably inherited. Compared to the wild type, the leaves of nrl7 narrowed and rolled inward, the number of vascular bundles between the leaf midrib and the adjacent vein was reduced to one, and the bulliform cells showed significant morphological change. Nevertheless, the plant height, filled grains per panicle, and filled grain weight per panicle in the mutant were 88.46%, 69.77%, 68.98%, respectively, of that in the wild type. Photosynthetic rate was significantly higher in the mutant than the wild type and accounted for 17% of that in C275. Transpiration rate did not differ. Map-based cloning revealed NRL7 on chromosome 3 between markers RM5444 and MM1300, delimited to a 185.14 kb region. These results will lay a good foundation for molecular cloning and functional analysis of NRL7.