水稻窄叶突变体nal20的表型分析与基因定位

Phenotypic Analysis and Gene Mapping of the Rice Narrow-leaf Mutant nal20

叶片作为植物光合作用的主要器官,其面积的大小影响着光能利用率和最终产量。为了研究水稻叶片形态建成的分子机制,利用60Co-γ射线诱变粳稻品种春江06,在M2代中得到1份窄叶突变体,命名为narrow leaf20(nal20)。该突变体叶片变窄、株高降低、分蘖增多、茎节间缩短、抽穗期提前。本研究重点调查了3片功能叶的形态,发现突变体叶片宽度减少了50%,叶片长度变化较小。细胞学观察表明,叶片变窄主要是由于表皮细胞数目的减少,而细胞大小变化不大。遗传分析表明,该突变体表型受1对隐性基因控制。利用具有多态性的In Del分子标记及nal20与Dular配制的F2定位群体,将该基因定位于第7染色体着丝粒区1.9 Mb范围内。二代测序结果表明,在该范围内有455 kb的大片段缺失。本研究结果为窄叶基因NAL20的克隆和功能分析奠定了良好基础,也为水稻株型改良提供了基因资源和育种材料。

Leaf is the major organ for photosynthesis in plant,and its area influences the light energy utilization efficiency and grain yield.To study the molecular mechanism of rice leaf morphology,we mutagenized the japonica cultivar Chunjiang 06 through 60Co-γradiation.A stable narrow leaf mutant named as narrow leaf20(nal20)was obtained in the M2 population.The nal20 mutant showed narrow leaf,reduced plant height,increased tiller number,shortened internodes,and earlier heading date.Here we mainly focused on the morphology of the flag leaf,the second top leaf and the third top leaf.We found that the blade width of the mutant reduced by 50%,compared with the wild type.Meanwhile,the variation on the blade length was relatively small.Cytological observation of leaf epidermal cells indicated that the reduced leaf width was mainly due to the decreased cell number,but not the cell size.Genetic analysis indicated that the narrow leaf phenotype was controlled by a recessive gene.Using the mutant plants from the F2 mapping population derived from a cross between nal20 and Dular,the candidate mutation locus was mapped to 1.9 Mb within the centromere of chromosome 7 by using polymorphic InDel markers.The next-generation sequencing result showed that a deletion of 455 kb occurred in the predicted region.Our study lays a good foundation for the cloning and functional study of the NAL20 gene and provides gene resources and breeding materials for the improvement of rice plant architecture.