低氧胁迫下24-表油菜素内酯对黄瓜幼苗根系生长及其无氧呼吸同工酶表达的影响

Effects of 24-epibrassinolide on root growth and anaerobic respiration isozyme expression of cucumber seedlings under hypoxia stress

采用营养液水培,研究了低氧胁迫下24-表油菜素内酯(EBR)对黄瓜幼苗根系生长及其无氧呼吸同工酶表达的影响。结果表明:低氧胁迫增强了黄瓜幼苗根系丙酮酸脱羧酶(PDC)、乙醇脱氢酶(ADH)、乳酸脱氢酶(LDH)同工酶的表达,低氧胁迫下施用外源EBR的第3天PDC、ADH同工酶的表达量分别提高了18.8%、28.8%,而第6、第9天PDC、ADH、LDH同工酶的表达减弱,比单纯低氧处理分别降低19.5%、25.6%、53.4%及26.4%、26.0%、28.4%;低氧胁迫至第9天,黄瓜幼苗根系的生长受到了显著抑制(P<0.05),而低氧胁迫下施用EBR,黄瓜幼苗根系的生长受抑制程度减轻,其根系总长、干重、根尖数较单纯低氧处理显著增加(P<0.05),低氧抑制了黄瓜幼苗根系的生长,低氧胁迫下营养液添加EBR可调节黄瓜根系无氧呼吸同工酶的表达,缓解低氧胁迫对黄瓜幼苗根系的伤害。

A hydroponic experiment was conducted to investigate the effects of exogenous 24-epi- brassinolide （EBR） on the root growth and anaerobic respiration isozyme expression of cucumber seedlings under hypoxia stress. Hypoxia stress induced the isozyme expression of root pyruvate decarboxylase （ PDC ） , alcohol dehydrogenase （ ADH ） , and lactate dehydrogenase （ LDH ）, while the application of EBR increased the expression of PDC and ADH isozymes by 18.8% and 28.8% on the 3rd day and decreased the expression of PDC, ADH, and LDH isozymes by 19.5% , 25.6% and 53.4% , and 26.4% , 26.0% and 28.4% on the 6th and 9th day, respectively. On the 9th day of hypoxia stress, the root growth was inhibited significantly （P〈0.05）, while the application of EBR alleviated the growth inhibition, as indicated by the significant increase of root length, dry weight, and root tips （P〈0.05）. These results indicated that hypoxia stress inhibited the root growth of cucumber seedlings, whereas EBR could alleviate the inhibitory effect of hypoxia stress via regulating the isozyme expression of anaerobic respiration enzymes in seedling roots.