持续干旱下接种PGPR对核桃苗抗氧化系统的影响

Effects of PGPR on the Antioxidant System in the Leaves of Juglans regia Seedlings Under Continuous Drought Stress

为探讨植物根际促生细菌(PGPR)对持续干旱胁迫下核桃叶片抗氧化系统的影响,采用盆栽试验,以1年生核桃苗为试验材料,研究持续干旱胁迫下接种PGPR对核桃苗株高和茎粗、叶片ROS积累和膜脂过氧化产物以及抗氧化酶活性、非酶类抗氧化物质含量的影响。结果表明,与正常浇水相比,持续干旱胁迫使核桃苗的株高和茎粗显著降低19.47%和15.49%,叶片超氧阴离子(O_(2)^(-·))、过氧化氢(H_(2)O_(2))和丙二醛(MDA)含量显著升高,同时,叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)与单脱氢抗坏血酸还原酶(MDHAR)活性以及还原型谷胱甘肽(GSH)含量均明显升高。在持续干旱逆境下接种PGPR则能显著促进株高和茎粗生长,有效减少叶片内ROS积累和MDA含量,显著提高叶片SOD、CAT、APX和MDHAR活性以及还原型抗坏血酸(AsA)、GSH含量,并不同程度提高叶片AsA/DHA(双脱氢抗坏血酸)和GSH/GSSG(氧化型谷胱甘肽)比值。以上分析认为,持续干旱逆境下核桃苗接种PGPR,可通过提高叶片抗氧化酶活性和非酶类抗氧化物质含量来有效清除活性氧,从而增强核桃苗的耐旱能力,促进其生长。

This study aimed to investigate the effects of plant growth-promoting rhizobacteria(PGPR)on the antioxidant system in the leaves of Juglans regia seedling under drought stress.The effects of PGPR inoculation on the plant height and stem diameter,the reactive oxygen species(ROS)accumulation and membrane lipid peroxidation products,as well as the antioxidant enzyme activities and the contents of nonenzymatic antioxidant substances in the leaves of Juglans regia seedling under drought stress were studied in a pot experiment by using one-year-old J.regia seedlings as experimental materials.The results indicated that in comparison with the normal watering treatment,the plant height and stem diameter were significantly decreased by 19.47%and 15.49%,respectively,and the contents of superoxide anion(O_(2)^(·-)),hydrogen peroxide(H_(2)O_(2))and malondialdehyde(MDA)in the leaves significantly increased.At the same time,the activities of superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX),glutathione reductase(GR)and monodehydroascorbate reductase(MDHAR),and glutathione(GSH)contents in the leaves under continuous drought stress significantly increased.However,PGPR inoculation under continuous drought stress could significantly promote the growth of plant height and stem diameter,effectively reduce the ROS accumulation and MDA content in the leaves,and significantly increase the activities of SOD,CAT,APX and MDHAR,as well as the contents of ascorbic acid(AsA)and GSH in the leaves.In addition,the ratios of AsA/DHA(didehydroascorbic acid)and GSH/GSSG(oxidized glutathione)in the leaves increased in different degrees.In conclusion,PGPR inoculation under continuous drought stress can effectively remove the ROS by means of increasing the activity of antioxidant enzymes and the content of non-enzymatic antioxidant substances in the leaves,and therefore enhance the drought tolerance of J.regia seedling,and promote their growths.