外源亚精胺对涝胁迫下玉米幼苗根的氧化伤害缓解效应

Mitigating effects of exogenous spermidine on oxidative injury induced by waterlogging stress in the roots of maize seedlings

【目的】研究亚精胺对涝胁迫下玉米幼苗根系抗氧化代谢酶活性及膜质过氧化产物的影响,为多胺的农业实践应用提供理论依据。【方法】以两个抗涝性不同的玉米品种(郑单958,抗涝性较弱;浚单22,抗涝性较强)为材料,设置正常供水、涝胁迫和涝胁迫+1 mmol/L亚精胺3个处理,处理6 d后取幼苗根测定其抗氧化代谢酶活性及膜质过氧化产物含量。【结果】涝胁迫下,两个品种玉米幼苗根系抗氧化酶活性、幼苗相对干物质增长速率(RDWIR)和根系活力均下降,相对电解质渗漏率(RELR)、超氧阴离子()产生速率和丙二醛(MDA)含量上升,且对抗涝性较弱的郑单958影响较为明显。施加亚精胺后,明显提高了涝胁迫下抗涝性较弱的郑单958幼苗根系的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸氧化酶(APX)活性、RDWIR和根系活力,降低了RELR、产生速率和MDA含量;与涝胁迫相比,其SOD、POD、CAT和APX活性、RDWIR和根系活力分别上升了46.4%、50.0%、96.0%、31.0%、33.5%和73.8%,而RELR、产生速率和MDA含量分别下降了28.4%、33.6%和19.4%。【结论】适当浓度的亚精胺能通过提高玉米幼苗根系中抗氧化代谢酶活性来降低的产生速率和MDA积累量,缓解涝胁迫对玉米根系质膜的伤害,从而提高玉米幼苗根系活力,促进玉米幼苗生长。

[Objective ]In order to provide theoretical basis for the agricultural practice application of polyamines ,the effects of exogenous spermidine （Spd） on the antioxidant enzyme activities and metabolite contents in maize seedling roots were studied under waterlogging stress. [Method]Two maize cultivars, Zhengdan 958 （waterlogging -sensitive）and Jundan 22 （waterlogging -tolerant）, were used as experiment materials. Three treatments were implemented, namely the control, waterlogging and waterlogging＋Spd（ 1 mmol/L）. After treating for six days, the antioxidant enzyme activities and metabolite contents in maize seedling roots were detected. [Result]Under waterlogging stress, the activities of these en- zymes（superoxide dismutase： SOD, peroxidase： POD, catalase： CAT, and ascorbic acid oxidase：APX）, relative drought weight increase rate （RDWIR） of seedling and root vigour decreased. Relative electrolyte leakage rate （RELR）, O2Tgen- eration rate and MDA contents increased, and the effect of waterlogging on Zhendan 958 （waterlogging -sensitive） was more obvious than Jundan 22 （waterlogging -tolerant）. However, Spd treatment markedly improved the activities of SOD, POD, CAT and APX, RDWIR and root vigour of Zhendan 958, but decreased RELR, O2 generation rate and MDA contents of Zhendan 958. Compared to waterlogging stress, the activities of SOD ,POD,CAT and APX,RDWIR and root vigour increased by 46.4%,50.0%,96.0%, 31.0%,33.5% and 73.8%, while RELR, O2 generation rate and MDA contents decreased by 28.4%,33.6% and 19.4%,respectively. [Conclusion]Under waterlogging stress, the appropriate concentration of Spd could decrease O2 generation rate and the contents of MDA via increasing the activities of antioxidant enzymes in maize seedlings roots to relieve the injury of waterlogging stress to the root plasma membrane and improve root vigour and the growth of maize seedlings.