水稻早衰突变体R7954(els)发育理化性质和亚显微结构特征

Physiological properties and ultra-structure features of an early leaf senescence rice mutant R7954( els)

以诱变获得的水稻早衰突变体R7954(els)为材料,研究了早衰突变对整个植株生长发育动态及剑叶亚显微结构的影响,以深入了解水稻早衰机制。结果表明,从分蘖始期起,突变体生长势弱,生长速度慢,随后叶片出现早衰症状,最终整株呈铁锈色和枯黄状。分蘖至成熟的5个重要生育时期,突变体抗氧化系统指标SOD活性,VC,VE和GSH含量降低,MDA积累增多;Chl a,Chl b和Chl(a+b)含量显著下降,净光合速率减弱。超微结构观察显示,随着衰老程度的加深,叶绿体内囊体结构解体严重,膜性氧化成分嗜锇颗粒、脂肪球等增多,细胞器整体结构崩解。

An early leaf senescence rice mutant R7954（ els）,obtained by60Co-γ irradiation from rice variety R7954,was applied to investigate the changes in physiological properties and in the ultra-structure of chloroplast in flag leaf during different developmental stages. Compared with wild type R7954,the mutant R7954（ els） showed weaker growth potential,lower growth rate and symptoms of early senescence,i. e. the presence of rusty and withered leaves since the beginning of the tillering stage. Lower activity of superoxide dismutase（ SOD）,deceased contents of vitamin C（ VC）,vitamin E（ VE） and glutathione（ GSH）,and higher content of malonaldehyde（ MDA）were observed,indicating a lower antioxidant system in the mutant. The mutant also showed lower content of chlorophyll a,chlorophyll b and chlorophyll（ a ＋ b）,resulting in photosynthetic decline. The ultra-structure of chloroplast in flag leaves in the mutant showed an increasing amount of disintegrating thylakoids,osmiophilic plastoglobuli and lipoid with the process of senescence,and the whole chloroplast were degraded at the mature stage.