一个控制水稻叶色白化转绿及多分蘖矮杆性状基因hw-1(t)的鉴定

摘要

通过空间诱变从光身稻品种Francis的M2群体中发现1株叶色白化转绿、多分蘖矮秆突变体hfa-1.hfa-1在三叶期之前完全白化,随后转绿.白化转绿表型受生长发育和温度调控.亚细胞结构观察发现hfa-1叶绿体发育异常抑制叶绿素合成,造成光合效率降低,产生白化表型.hfa-1的多分蘖表型是由于高节位分蘖芽激活所致,初步鉴定与苗期叶片IAA(吲哚乙酸)含量无关.hfa-1的矮生性则由节间长度缩短所致,与苗期GA(赤霉素)的合成和信号 传导无关.遗传分析表明hfa-1的白化转绿、多分蘖矮秆表型受单隐性核基因hw-1(t)控制.利用hfa-1与粳稻品种02428杂交获得的F2群体将hw-1(t)定位在水稻第4染色体长臂上两个InDel标记HW27和HW7间46.9 kb的物理距离内,该区域有13个阅读框架,其中LOC_Os04g57320编码IMMUTANTS蛋白,推测为hw-1(t)的候选基因.%A rice (Oryza sativa L.) mutant hfa-1 exhibiting green-revertible albino, high-tillering dwarf was detected from a M2 population of an American variety Francis by space mutagenesis. Hfa-1 displayed distinctive albino before 3rd leaf stage but finally turned to normal green after 3rd leaf stage, and the expression of this phenotype was conditionally controlled by development and temperature. Examining ultrastructure and measuring chlorophyll content indicated that hfa-1 showed albino due to abnormal development of chloroplast, which resulted in inhibiting chlorophyll synthesis and decreasing photosynthetic efficiency. Moreover, the increased tiller number of hfa-1 was ascribed to initiate more higher-order tiller buds. Further endogenous hormones analysis demonstrated that the enhanced tillering capacity of hfa-1 might not result from inhibiting the synthesis of IAA. In addition, the dwarfism of hfa-1 was caused by shortening internodes and was independent of biosynthesis and signal transduction of GA. Genetic analysis indicated that the phenotype of green-revertible albino, high-tillering dwarf in hfa-1 was controlled by a recessive nucleic gene, namely hw-l(t). Using a large F2 mapping population derived from a cross between hfa-1 and an japonica rice variety, 02428, hw-l(t) was fine mapped into a 46.9 kb of physical distance between two InDel markers, HW27 and HW7 on chromosome 4, where 13 open reading frames were predicted. In the mapping interval LOC_Os04g57320 encoded a IMMUTANTS protein, which was the most properly candidate gene of hw-l(t).