乙烯对低磷胁迫下大豆根形态和生理特性的影响

利用沙培方法研究了乙烯对磷胁迫下大豆幼苗的生理影响。结果表明:磷胁迫下大豆主根长度降低50%,侧根长度增加46%,侧根数目增加64%。缺磷时大豆根系磷含量降低,根系活力和根系组织酸性磷酸酶活性分别是全磷培养植株的1.2和1.3倍;与供磷植株相比,缺磷时大豆干物质累积量显著降低,缺磷主要抑制了地上部分干物质累积,而根系干物质累积几乎不变,根冠比增大。磷胁迫使大豆乙烯含量增加,但乙烯释放量被乙烯拮抗剂Co2+抑制。外源乙烯利抑制全磷大豆主根伸长,促进缺磷大豆侧根生长;乙烯拮抗剂Co2+逆转了低磷和乙烯对主根的抑制,减少侧根数目。乙烯利能够增加大豆幼苗根系活力和根系组织酸性磷酸酶活性,降低大豆生物量,增加根冠比,且磷胁迫时效果更为明显。

Effect of Ethylene on Morphology and Physiological Characteristic of Soybean Seedlings under Low-Phosphorus Stress

Plants grown in phosphorus-deficient solutions often exhibit up-regulation of root secreted acid phosphatase activity and enhanced ethylene production.To determine the role of ethylene in response of plants to P deficiency,we investigated the effects of ethylene donor ethephon and ethylene synthesis antagonists(CoCl2)on P concentrations in roots of soybean seedlings grown in P-sufficient(1 mmol·L-1 H2PO4)and P-deficient(10 μmol·L-1 H2PO4)solution.There was an increase in ethylene production when seedlings grown in P-deficient solutions,CoCl2 abolished the P deficiency-induced ethylene production.The main root length under the low phosphorus application treatment was about 50% lower than that of the control,and the main root length of soybean seedlings grown in P-sufficient solutions was insensitive to Co2+,while Co2+enhanced main root length for those grown in P-deficient solutions,suggesting that P-deficiency induced decrease in root length can be reversed by inhibiting ethylene production.Under P-deficient conditions the lateral root number increased by 64%,and the longest lateral root increased by 46% compared with the control.The lower root length and higher lateral root number induced by ethylene were reversed by Co2+.There was an increase in root activity and acid phosphatase(APase)activity when seedlings grown in P-deficient solutions,and the increase in root activity and APase activity were markedly induced by ethylene.Phosphorus deficiency affects the shoot dry mass accumulation and almost has no effects on accumulation of root dry mass.The root/shoot ratio was enhanced by ethylene.Ethylene promoted P concentration of P-deficient seedlings.Results suggest that ethylene induced by P deficiency may play an important role in P-stress adaption of soybean.