水稻叶片内卷突变体rl(t)的鉴定与基因定位

Identification and Gene Mapping of a Rolled Leaf Mutant rl(t) in Rice

【目的】叶片是水稻理想株型的重要内容,叶片适度卷曲可以提高光合效率。对卷叶相关基因进行遗传分析和初步定位,为下一步的基因克隆与功能分析提供研究基础。【方法】利用EMS诱变雄性不育保持系宜香1B获得一份稳定遗传的叶片向内卷曲突变体,暂命名为rl(t)。在成熟期,测定野生型和rl(t)的主要农艺性状;在分蘖期,取野生型和rl(t)叶片用FAA固定液固定进行石蜡切片,同时,用野生型和rl(t)剑叶测定叶绿素含量;在抽穗期,利用Li-6400便携式光合仪测定10株抽穗期的野生型和rl(t)的光合参数;将rl(t)与野生型及日本晴杂交,观察F_1植株表型,对F_2表型分离进行χ~2测验,对突变体进行遗传分析。以rl(t)/日本晴的F_2群体为材料,利用BSA法进行定位。【结果】与野生型相比,突变体叶片向内卷曲明显,叶片更加直立,叶色变深,其他主要农艺性状均有不同程度降低。光合特性分析表明,突变体比野生型具有更高的光合色素含量,但光合效率没有明显差异。叶片组织切片观察表明,突变体中泡状细胞变小可能是导致叶片卷曲的主要原因。遗传分析表明,该突变体受一对隐性核基因控制,利用突变体与日本晴的F_2群体进行基因定位,最终将该基因定位在第7染色体长臂InDel标记Ind3和Ind4间610 kb的物理区间。【结论】rl(t)叶片内卷是由于近轴面泡状细胞面积减小。RL(t)定位区间内未见卷叶相关基因报道,推测RL(t)可能是一对新基因。

【Objective】Rice leaf is an important factor for ideal plant architecture in rice,and moderate rolling of the leaves can improve light acceptance and photosynthetic rate.Genetic analysis and primary mapping of the target genes are useful in map-based cloning and function analysis.【Method】A stable inherited mutant,derived from an indica maintainer line Yixiang1B by EMS treatment,exhibited significantly inward-rolling,more erect and green leaves.At the maturity stage,10plants of rl(t)and its wild type(WT)were randomly selected to measure the main agronomic traits including leaf rolling index and leaf erect index.At the tillering stage,the same part of leaf of rl16(t)and WT was taken and fixed by FAA for paraffin sectioning.The chlorophyll content in rl16(t)and WT was tested at the same stage.At the heading stage,the photosynthetic rate,intercellular carbon dioxide concentration,stamatal conductance,and transpiration rate of flag leaves inrl15(t)and WT were measured by using the portable gas exchange system Li-6400.【Result】Compared to wide type,rl(t)displayed reduced plant height,shortened panicle length as well as other agronomic traits.Leaf photosynthetic pigmentcontents were significantly higher than those of the wild type.However,no difference is observed in photosynthetic efficiency.Cytological analysis showed that the rolled leaf phenotype was possibly caused by the reduced size of bulliform cells.Geneticanalysis indicated that rolled leaf phenotype in rl(t)was controlled by a single recessive nuclear gene.In an F2population derived from a cross between the mutant and Nipponbare,RL(t)was mapped to a610kb region between Ind3and Ind4on the long arm of chromosome7.In target region,there are102genes altogether.【Conclusion】The rolled leaf of rl(t)was due to increased area of bulliform cells in adaxial layer and no gene related to roll-leaf was reported in the target region.So,RL(t)gene would be a putative novel rolled leaf gene.