水稻斑点叶突变体hm197的鉴定及其基因定位

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spl^hm197,并将其定位在第4染色体长臂上140 kb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O_{2 ?}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。

Identification and Gene Mapping of a Spotted-leaf Mutant hm197 in Rice

A stable inherited rice spotted-leaf mutant hm197 was isolated from a diepoxybutane-induced IR64 mutant bank. Under natural conditions, brown lesions were first observed on the tips of the mutant leaves 10 weeks after sowing, and spread gradually downward to cover the whole leaf blades. Genetic analysis indicated that the mutant trait was controlled by a novel single recessive nuclear gene, tentatively termed as spl^hm97,located in the long arm of chromosome 4. Agronomic traits including the plant height, seed-setting rate and 1000-grain weight were significantly decreased in hm197. The initiation of brown lesions in hm197 was induced by natural sun light. In addition, the photosynthetic pigment contents and net photosynthetic rate in the mutant were significantly lower than those in the wild type IR64. Histochemical analysis showed that H₂O₂ and accumulation were presented in and around the lesions in hm197. Furthermore, senescence-related parameters including the activities of SOD, APX,total soluble protein and MDA contents were also significantly altered in the mutant while resistance to bacterial blight pathogens was largely enhanced in the mutant in contrast to the wild type IR64.