水稻叶片早衰及盐敏感突变体osles的生理分析和基因精细定位

突变体osles(Oryza sativa leaf early-senescence and salt-sensitive)是利用60Co辐射诱变籼稻品种自选1号后筛选获得的,该突变体从分蘖期开始叶片就出现早衰,主要表现为叶尖和叶边缘变黄,伴有红褐色斑点。此外,盐胁迫下,不仅突变体叶片卷曲枯萎,而且植株高度和生物量显著降低。与野生型相比,突变体除倒一叶外,倒二和倒三叶在分蘖期的叶绿素含量均显著降低,而POD活性则在倒一、倒二和倒三叶中依次显著升高;突变体3片叶片的MDA含量均高于野生型15%左右。除倒一叶外,突变体的SOD活性均显著高于野生型。此外,突变体和野生型3片叶中的可溶性蛋白含量依次下降,但突变体的倒一和倒二叶中的可溶性蛋白含量显著高于野生型,而倒三叶则相反;遗传分析表明,osles突变性状受一隐性基因控制,借助图位克隆技术将控制该性状的基因精细定位于第6染色体长臂的IN6-005769-11/12和RM20547两个标记之间,物理距离为210 kb,为进一步克隆该基因并揭示叶片的早衰分子生理机制奠定基础。

Physiological Characterization and Gene Fine Mapping of a Leaf Early Senescence and Salt-Sensitive Mutant osles in Rice

A osles (Oryza sativa leaf early-senescence and salt-sensitive) mutant, produced by ⁶⁰Co γ-radiation treatment of indica cultivar Zixuan 1, was identified. The osles showed yellow at tip and margin of leaf blade with red brown spots during growth at tillering stage. In addition, under salt stress, the leaves were rolled and wilted, and plant height and plant dry weight were significantly decreased. Compared with the control plant, in the mutant plant, the contents of chlorophyll and soluble protein decreased significantly, while the activities of SOD and POD increased significantly; higher soluble protein content appeared in the 1st and 2nd leaves from top, and decreased in the 3rd leaf. Genetic analysis indicated that osles was controlled by a recessive nuclear gene, which was finely mapped in a 210 kb interval between two markers IN6-005769-11/12 and RM20547 on long arm of chromosome 6. These results will facilitate the positional cloning and functional studies of the gene.