【作者】 李利红；

【导师】 赵会杰；

【作者基本信息】 河南农业大学 ， 作物生理学， 2010， 博士

【摘要】 黄淮冬麦区灌浆期高温强光逆境发生频繁,造成光合机构损伤,光合功能过早衰退,阻碍籽粒发育,造成严重减产。本论文研究了外源水杨酸（SA）、Ca2+和一氧化氮对灌浆期高温强光胁迫下小麦叶片类囊体D1蛋白含量、蛋白激酶活性、叶绿素荧光参数、电子传递速率、抗氧化活性和细胞膜稳定性的调节作用,旨在为进一步阐明高温强光破坏光合机构的机理和生产中采取抗逆应变技术提供科学依据。试验于河南农业大学科教园区进行,以豫农949为材料,设置盆栽为主,土壤为潮土。于灌浆期（开花后20天）分别用0.5mmol·L-1SA、10mmol·L-1Ca2+和0.1mmol·L-1硝普钠（SNP,—氧化氮供体）溶液预处理小麦叶片,以水预处理为对照,然后将植株进行高温强光（36℃,1800μmol·m-2·s-1）处理,于照光1h、2h、3h和恢复后分别采样,进行生理生化指标测定。主要结果如下：1外源SA、Ca2+和NO对高温强光胁迫下小麦类囊体D1蛋白含量和蛋白激酶活性的调节作用本文试验结果表明,高温强光胁迫下,灌浆期小麦遭受高温强光的伤害,叶片PSⅡ反应中心发生可逆破坏,D1蛋白含量和磷酸化水平降低,D1蛋白发生降解；蛋白激酶活性和磷酸酯酶活性呈下降趋势,恢复期不能恢复到胁迫前水平。小麦叶面喷施低浓度SA （0.5mmol·L-1）,可显著提高强光胁迫下的蛋白激酶活性,磷酸酯酶活性仅在胁迫前和恢复期显著提高,酶活性的提高促进了PSⅡ蛋白的磷酸化和去磷酸化反应,加快了D1蛋白周转,提高了D1蛋白含量和磷酸化水平,有效维持了PSⅡ反应中心结构的稳定,降低了光抑制伤害。小麦叶面喷施一定浓度Ca2+（10mmol·L-1）,显著提高了胁迫前、照光期及恢复期的蛋白激酶活性和磷酸酯酶活性,大大提高了D1蛋白含量和磷酸化水平。本试验表明,小麦叶面喷施Ca2+显著提高了小麦抗光抑制能力,其提高作用强于水杨酸和NO。小麦叶面喷施低浓度NO供体硝普钠（0.1mmol·L-1）,仅仅提高了胁迫前的D1蛋白含量和D1蛋白磷酸化水平,且此期蛋白激酶活性和磷酸酯酶活性极显著高于对照；照光期间的激酶活性高于对照,但是酯酶活性低于对照；恢复期激酶活性低于对照,酯酶活性极显著高于对照,因此认为,NO主要是提高了胁迫前的磷酸化和去磷酸化反应,维持照光期间的磷酸化反应,促进恢复期间的去磷酸化反应,来保护蛋白免受光抑制破坏。2外源SA、Ca2+和NO对高温强光胁迫下小麦叶片PSⅡ功能的调节作用本文试验结果表明,胁迫下PSⅡ功能减弱,最大光化学效率（Fv/Fm）、实际光能捕获效率（φPSⅡ）和光化学猝灭系数（qP）下降,非光化学猝灭系数（NPQ）上升；PSⅡ电子传递速率、PSI电子传递速率和全链电子传递速率及净光合速率下降。SA、Ca2+和NO均有效抑制了PSⅡ功能的下降,维持了光合作用,提高了抗氧化酶活性,减少了活性氧积累,减轻了细胞膜伤害,保护了小麦叶片免受光抑制破坏。三者均延缓了最大光化学效率（Fv/Fm）、实际光能捕获效率（φPSⅡ）和光化学猝灭系数（qP）的下降,抑制了非光化学猝灭系数（NPQ）的上升,延缓了PSⅡ电子传递速率、PSI电子传递速率和全链电子传递速率及净光合速率的下降,3外源SA、Ca2+和NO对高温强光胁迫下小麦叶片抗氧化活性和细胞膜稳定性的调节作用本文试验结果表明,胁迫造成细胞活性氧积累,细胞膜受到伤害,抗氧化酶SOD、APX和CAT的活性均下降,H2O2含量和超氧阴离子自由基（0（?））浓度上升,丙二醛（MDA）积累,相对电导率增加。SA、Ca2+和NO明显提高了SOD、APX和CAT的活性,减少了H2O2和0（?）的积累,抑制了丙二醛（MDA）浓度和相对电导率的增加。因此,本试验结果表明,SA、Ca2+和NO三种外源信号物质通过诱导小麦叶片蛋白激酶活性,提高D1蛋白的可逆磷酸化反应,发挥了对光合机构完整性和PSⅡ功能的保护作用,从而保持了光合电子传递,提高了抗氧化酶活性,减轻了细胞膜伤害。本论文的研究结果不仅丰富了小麦光合逆境生理研究,也丰富了水杨酸、Ca^2-和NO的逆境生理研究。更多还原

【Abstract】 In China’s Huanghuai winter wheat zone, cross-stress of heat and high irradiance occurs frequently, which results in damage to photosynthetic apparatus, decline of photosynthesis in leaves, retard of seed growth and decrease in grain yield. In this paper, we studied the regulating effects of exogenous salicylic acid(SA), calcium ion (Ca2+)and nitric oxide (NO) on chloroplast protein kinase(PK), phosphorylation of D1 protein, performance of photosystemⅡ(PSⅡ), resistance to oxidative damage induced by high irradiance. The aim was to provide the reference for selection of the exogenous substance which could prevent photosynthetic apparatus from the damage caused by high temperature and irradiance stress.Using wheat variety "Yunong 949" as material, the experiments were carried out on the experimental farm of Henan Agricultual University. Wheat seeds were planted in pots and routine culturing system was adopted. Foliar sprayings of salicylic acid (SA, 0.5mmol·L-1),Ca2+(10mmol·L-1), sodium nitroprusside (SNP, 0.1mmol·L-1; which was used as NO donor) and water (as control) were done the 20th day after anthesis (grain filling stage). Then the plants were exposed to irradiance of 1800μmol·m-2·s-1 provided by 1000W tungsten lamp and temperature of 36℃. The physiological and biochemical characteristics of flag leaves were determined at 1,2,3 hours after irridance and at the stage of recovery under proper condition. The main results were as follows:1. Effects of exogenous SA, Ca2+ and NO on the content of D1 protein and the activity of protein kinases under heat and high irradiance stress in wheat leavesCross-stress of heat and high irradiance caused reversible damage to D1 protein and PSⅡfunction. The contents of D1 and D1* (phosphorylated D1 protein) decreased because of the degradation of D1. The activity of protein kinse (PK) and phosphatase declined.Pretreatment with SA, Ca2+ and NO had the distinct effects on the integrated structure of D1 protein. They all heightened the contents of D1 and D1*. Application of SA at 0.5mmol·L-1 had remarkably lifted the activity of PK, but the activity of phosphatase was remarkablrly lifted only before and after stress. Application of Ca2+ at 10mmol·L-1 had markedly lifted the activity of PK and the phosphatase. Application of SNP with 0.1mmol·L-1 had markedly lifted the activity of PK before and during stress; the activity of phosphatase was advanced before and after stress. It was concluded that Ca2+ had better effect on protecting D1 than S A and NO.2. Effects of exogenous SA, Ca2+ and NO on the function of PSⅡunder heat and high irradiance stress in wheat leavesHeat and high irradiance stress led to the lower of Fv/Fm,ΦPSⅡ, qp and electron transport rate(ETR) in PSI, PSⅡor whole chain and Pn. Spraying SA, Ca2+ and NO had effectively alleviate the damage to the function of PSⅡcaused by high temperature and irradiance stress. They all retarded the drop of Pn, Fv/Fm,ΦPSⅡ, qp, ETR, Pn.and the rise of NPQ.3. Effects of exogenous SA, Ca2+ and NO on the stress-induced oxidative damage and the stability of membrane under heat and high irradiance stress in wheat leavesCompared with control, spraying SA, Ca2+ and NO solution to leaves during grain-filling increased the antioxidant capacity of wheat leaves.Exogenous SA, Ca2+ and NO could maintain higher activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate-peroxidase (APX), reduced accumulation of H2O2,O2·and MDA content and keep lower relative permeability of cell membrane.In conclusion, it was turned out that spraying wheat plants with proper concentration of SA、Ca2+ and SNP during grain-filling could prevent the leaves from the photoinhibition induced by heat and high irradiance stress, keep higher phosphorylation level of D1 protein effectively, maintain higher activity of PSⅡ, improve photosynthetic characteristics to some extent, increase the activity of SOD,CAT and APX, decrease the content of H2O2, O2·-, relative conductance and the concentration of MDA.更多还原