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通过双环氧丁烷(diepoxybutane)诱变籼稻品种IR64获得遗传稳定的水稻褐色斑点叶突变体hm197。在自然条件下,该突变体褐色斑点自播种后10周开始于叶尖出现,而后慢慢扩散至全叶。遗传分析表明,该褐色斑点性状受一对隐性核基因控制,暂名splhm197,并将其定位在第4染色体长臂上140kb的区段内。与野生型IR64相比,突变体株高、结实率和千粒重等农艺性状均显著下降。遮光处理表明,hm197褐色斑点的形成受自然光照的诱导。此外,hm197光合色素含量和光合效率也比野生型显著降低。组织化学分析表明,突变体中有过氧化氢和大量超氧阴离子O2的沉积。与IR64相比,hm197叶片中清除氧自由基酶系统中SOD和APX活性极显著上升,其余均极显著下降,同时伴随总可溶蛋白含量下降以及MDA含量上升,hm197表现出早衰迹象。抗病性鉴定表明,与野生型相比突变体对白叶枯病菌的抗性显著增强。
A rice brown spotted leaf mutant hm197 was obtained by mutagenesis of indica rice IR64 with diepoxybutane. Under natural conditions, the mutant brown spot appeared at the tip of the leaf tip 10 weeks after sowing, and then slowly diffused to the whole leaf. Genetic analysis indicated that the brown spot trait was controlled by a pair of recessive nuclear genes, tentatively named splhm197, and located in the segment of 140kb on the long arm of chromosome 4. Compared with wild-type IR64, the agronomic traits such as plant height, seed setting rate and 1000-grain weight of mutant were significantly decreased. Shading showed that the formation of hm197 brown spots was induced by natural light. In addition, hm197 photosynthetic pigment content and photosynthetic efficiency also significantly lower than the wild-type. Histochemical analysis showed that hydrogen peroxide and a large number of superoxide anion O2 deposition in the mutant. Compared with IR64, the activities of SOD and APX in the scavenging oxygen free radical system of hm197 leaves increased significantly, and the balance decreased significantly, accompanied by the decrease of total soluble protein content and MDA content, hm197 showed the signs of premature aging. Disease resistance identification showed that the resistance of the mutant to Xanthomonas oryzae was significantly increased compared to the wild type.