干旱胁迫对杏脂氧合酶活性的影响

为了研究脂氧合酶(LOX)在植物干旱反应中的作用,以抗旱的山杏和抗旱性弱的龙王帽实生苗为试材,观察了自然干旱过程中叶片的生长状况以及测定了土壤含水量、新叶生长率、叶片脱落率、根和叶片的LOX活性。结果表明,在自然干旱过程中随着土壤含水量的降低,山杏和龙王帽的新叶增长率也下降。干旱后期山杏比龙王帽的新叶增长速率下降快、生长停止早。干旱使山杏比龙王帽叶片早脱落,而且落叶比率明显高于龙王帽。自然干旱时杏的LOX活性表现为叶片升高,在根中变化不大。而且山杏叶片的LOX活性增加幅度比龙王帽大,峰值出现比龙王帽早。因此,干旱条件下抗旱的山杏叶片脂氧合酶活性比龙王帽提早增加而且叶片易早脱落。山杏叶片LOX活性急剧升高出现在叶片萎蔫衰老之前,推测LOX活性增强可能与引发衰老有关。

Relationship between lipoxygenase activity and senescence in apricot leaves under drought stress

Experiment was conducted with seedlings of apricot drought tolerant genotype (DT) Prunus armeniaca L. var. ansu Maxim. and drought sensitive genotype (DS) Armeniaca vulgaris Lam. cv. Longwangmao for studying the role of lipoxygenase (LOX) in drought stress and its relationship with leaf senescence. The two genotype seedlings given a soil drying treatment showed a significant restriction of leaf growth rate (compared to both their daily growth rate before drying and the average growth rate of well-watered plants on the same day). The growth rate of DT decreased more in comparison to DS. Moreover, abscission of leaves from apricot seedlings occurred due to drought stress. Earlier abscission was observed in DT and higher level of abscission was measured in DT than in DS. The LOX activity in old leaves of both genotype seedlings increased while water was withheld. There was no significant detectable difference in the LOX activity in the roots of well watered and non-watered seedlings of two genotypes. The lipoxygenase activity in the leaves of DT was more efficient in comparison to DS on day 6 since water withheld, and DT seemed to be submitted to senescence. Moreover, the increase of lipoxygenase activity was found before the senescence symptoms of leaf in DT. These results indicated that the enhancement of LOX activity in leaves induced by water deficit might be related to leaf senescence.