水稻短根白化突变体sra1生理生化分析及基因定位

叶色突变体是研究光合作用及叶绿素合成与降解途径的理想材料,有助于了解高等植物叶绿体发育和光合作用的调控机制。利用甲基磺酸乙酯(EMS)处理西农1B,获得一个短根白化突变体sra1 (short radicle and albino 1),从出芽至第三叶期叶片始终为白色,胚根较同时期野生型明显变短。对相同位置的叶片观察发现,西农1B叶肉细胞叶绿体含量丰富且膜系统发育完整,而sra1叶肉细胞液泡化严重,叶绿体数目明显减少或没有,基粒类囊体垛叠松散且稀少。生理生化分析发现sra1叶绿素a、叶绿素b和类胡萝卜素含量接近于零,净光合速率为负值。遗传分析表明该短根白化表型由单个隐性核基因控制,最终将SRA1定位于水稻第3染色体长臂InDel标记Z-20和Z-42间,物理距离约657 kb,是一个未报道的新基因。

Physiological and biochemical analysis and gene mapping of a novel short radicle and albino mutant sra1 in rice

The leaf color mutant is an ideal material for studying the process of photosynthesis and the pathways of chlorophyll synthesis and degradation. Studies on rice leaf color mutants are helpful to explain the gene network of chloroplast development and photosynthesis in higher plants. The mutant sra1, derived from the progeny of EMS-treated indica rice Xinong 1B. Leaves of sra1 were white in color from budding to the third leaf, and the radicle of sra1 was significantly shorter than that of wild type in the same stage. The observation of leaves in the same position showed that in Xinong 1B, the chloroplast of mesophyllous cells was abundant and the membrane system was fully developed, while in sra1, the vacuolarization of mesophyll cells was serious, the number of chloroplasts was significantly reduced or absent, and the granule thylakoids were loosely folded. The contents of chlorophyll a, chlorophyll b, and carotenoid in sra1 were close to zero, and the net photosynthetic rate was negative. Genetic analysis indicated that the short-root and albino phenotype was controlled by a single recessive nuclear gene, and SRA1 was localized between the long-arm InDel markers Z-20 and Z-42 of rice chromosome 3. The physical distance between the two InDel markers was about 657 kb. No genes related to chloroplast and root development have been reported in this interval, indicating that sra1 is a novel mutant. The sra1 is a novel mutant with albino and accompanying short roots, suggesting that SRA1 may be involved in regulating chloroplast and root development.