过氧化氢提高燕麦幼苗耐碱性的活性氧代谢和渗透调节

Exogenous H_2O_2 improves alkali resistance of oat seedlings by regulating active oxygen metabolism and osmolyte accumulation

为探明过氧化氢(H_2O_2)提高燕麦耐碱性的作用,以‘定莜6号’幼苗为材料,采用珍珠岩栽培方法,在幼苗三叶一心期根部浇灌75mmol·L^(-1) NaHCO_3或添加二甲基硫脲(DMTU,H_2O_2淬灭剂)或抗坏血酸(ASA,H_2O_2清除剂)模拟碱胁迫,通过叶面喷施0.01mmol·L^(-1) H_2O_2来观测H_2O_2对碱胁迫下幼苗生长、活性氧代谢和渗透溶质积累的影响。结果表明:喷施H_2O_2能够缓解NaHCO_3胁迫对燕麦幼苗生长的抑制,降低幼苗叶片O_2·^-、H_2O_2和丙二醛含量,提高超氧化物歧化酶、抗坏血酸过氧化物酶等抗氧化酶活性和非酶抗氧化剂抗坏血酸、谷胱甘肽含量;使过氧化氢酶、过氧化物酶活性及渗透溶质可溶性糖、游离氨基酸和脯氨酸含量显著降低,有机酸和叶绿素含量明显提高,而可溶性蛋白质含量则变化不大;添加DMTU和ASA后有效逆转了喷施H_2O_2对NaHCO_3胁迫燕麦生长受抑和生理响应的调节。采用主成分和隶属函数分析显示,喷施H_2O_2显著提高了NaHCO_3胁迫下燕麦幼苗的综合评价值,添加DMTU和ASA完全或部分逆转了H_2O_2的作用。因此,外源H_2O_2是通过调控活性氧代谢和渗透调节来缓解碱胁迫导致的氧化伤害和生长抑制,从而增强燕麦幼苗的耐碱性。

Hydrogen peroxide(H2O2)is a signaling molecule with diverse physiological functions in plants.The objective of this study was to determine whether exogenous H2O2 could improve the alkali tolerance of oat(Avena nuda)seedlings.Seedlings of oat cv.Dingyou No.6 at the three-leaf stage were irrigated with 75 mmol·L-1 NaHCO 3 solution containing dimethylthiourea(DMTU,a quencher of H2O2)or ascorbate(ASA,a scavenger of H2O2),and the leaves were sprayed with 0.01 mmol·L-1 H2O2.Seedlings irrigated with water served as the control.After 7 days of treatment,seedling growth,chlorophyll content,active oxygen metabolism,and osmotic accumulation in leaves were measured.The results showed that treatments with exogenous H2O2 remarkably relieved the growth inhibition caused by NaHCO 3 stress,and significantly decreased the contents of O2·-,H2O2,malondialdehyde,soluble sugars,free amino acids,proline,and activities of catalase and peroxidase.Treatments with exogenous H 2O 2 also increased the activities of superoxide dismutase and ascorbate peroxidase,and increased the contents of ascorbic acid,glutathione,organic acids,and chlorophyll in leaves of oat seedlings.However,none of the treatments affected the soluble protein content.The regulating effects of exogenous H2O2 on alkali stress could be reversed by treatment with DMTU or ASA.A comprehensive evaluation based on principal components and subordinate function analyses revealed that foliar spraying with H2O2could improve the alkali stress adaptability of oat seedlings,and the promoting effect of H2O2 could be reversed by DMTU or ASA.Together,the results showed that H2O2 can increase alkali resistance in oat seedlings by regulating active oxygen metabolism and osmotic accumulation in leaves oat plants under alkali stress.