水稻茎秆脆性及叶尖枯死突变体fld1的鉴定与基因定位

用EMS诱变籼型水稻(Oryza sativa)恢复系缙恢10号, 获得稳定遗传的脆性叶尖枯死突变体fld1, 苗期植株呈现脆性和叶尖枯死, 机械强度显著下降, 一直持续到成熟。突变体fld1茎秆中的纤维素和木质素含量仅分别为野生型的67.92%和50.16%, 差异达极显著水平。与野生型相比, fld1叶片中的光合色素含量呈现一定程度的下降。其中, 类胡萝卜素含量在衰老和正常部位均极显著降低, 净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)也极显著降低, 胞间CO₂浓度(C_i)则极显著升高。遗传分析表明, fld1的脆性和叶尖枯死性状共分离, 且受1对隐性核基因调控。利用西农1A/fld1和fld1/日本晴的F₂群体, 最终将FLD1定位在第9染色体Indel标记Ind09-2与Ind09-3之间215 kb的物理距离内, 包含33个注释基因。研究结果为下一步基因的克隆和功能研究奠定了基础。

Identification and Gene Mapping of a Fragile and Leaf-tip Dead Mutant fld1 in Oryza sativa

A fragile and leaf-tip dead mutant, fld1, was identified from the progeny of the restorer line Jinhui10 with seeds treated with ethyl methanesulfonate (EMS). The mutant showed stable inherited traits of brittleness as well as dry and withered leaf tip throughout development. Besides showing significantly decreased mechanism strength, in fld1, cellulose and lignin content in culm occupied only 67.92% and 50.16% of that in the wild type, for a significant difference. The content of photosynthetic pigment was lower in fld1 than the wild type, as was that of carotenoid. Photosynthetic parameters of photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r) were lower and intercellular CO₂ concentration (C_i) were higher in fld1 than the wild type. The mutational traits of brittleness and dead leaf-tip were co-segregated and controlled by one recessive nuclear gene. The FLD1 gene was mapped on chromosome 9 between Indel markers Ind09-2 and Ind09-3 with 215 kb physical distance with F₂ groups of Xinong 1A/fld1 and fld1/Nipponbare. The restricted region has 33 annotated genes. These results provide a stable foundation for FLD1 gene cloning and its application in molecular breeding.