水稻幼苗叶绿体保护系统对干旱的反应

RESPONSES OF PROTECTION SYSTEM IN CHLOROPLASTOF RICE SEEDLINGS TO THE DROUGHT

摘要:

干旱条件下水稻耐旱品种湘中籼2号比不耐旱品种湘早籼12号具有较低的质膜相对透性、叶绿素含量降低较少，表明耐旱品种受伤害较轻，两个品种的抗坏血酸。过氧化物酶（AsA-POD）均降低，但耐旱品种降低较少。耐旱品种的谷胱甘肽还原酶（GR）活性在干旱初期提高，不耐旱品种的则变化不大。0.01 mmol/L的百草枯和0.1 mmol/L的H₂O₂亦能诱导耐旱品种的ＧＲ活性，但对不耐旱品种的ＧＲ活性不受影响，说明可能是干旱诱导的氧化胁迫诱导了ＧＲ活性。干旱条件下两品种的抗坏血酸（ASA）和还原型谷胱甘肽（GSH）含量均是先升后降，但耐旱品种提高幅度较大。结果表明，耐旱品种的叶绿体保护系统的活性比不耐旱品种的高。

Abstract:

Under drought condition, the drought-tolerant riee cultivar "Xiangzhongxian No.2" showed lower relative plasmalemma permeability and less reduction in chlorophyllcontent as compared with drought-sensitive cultivar "Xiangzaoxian No. 12" , whichindicated that the drought-tolerant cultivar was less demaged by drought stress. Ascorbate-peroxidase (AsA-POD) activity decreased in both cultivars, but less decreased in drought-tolerant one. The glutathione reductase (GR) activity increased at the beginning of drought in drought-tolerant cultivar，but that did not change obviously in drought-sensitive one．The results also showed that GR activity could be induced by paraquat(0.01 mmol／L)and H₂0₂(0.1 mmol／L)in drought-tolerant cultivar，but they had no effects on drought_sensitive one，which indicated that the increase of GR activity in drought-tolerant cultivar under drought stress might result from the induction by oxidative stress．In addition，the contents of ascorbate (AsA) and reduced glutathione (GSH) showed a tendency of being increased at first，then decreased in both cultivars，but with greater increase in the drought-tolerant cultivar．The results suggested that drought_tolerant cultivar had better protection system in chloroplasts against drought stress than the drought-sensitive cultivar.