臭氧与光照协同伤害葡萄叶片光合机能的机理

Ozone, a primary enviromental contamination factor, has become much higher than PM2.5. Synergetic induction of photooxidation by ozone and light hurts grapevine leaves seriously. On the base of suscepbility of different grapevine varieies to zone stress, we treated grapevines with light and ozone stress to clarify the injury threshold valule of ozone under different light intensity, Studied the sequencing effect of light intensity and ozone stress treatment to stomatal movement; PSⅡactivity and D1 protein content were tested to clarify the synergetic effect of light intensity and ozone stress on PSⅡafter treated with chloramphenicol; Studied the ozone stress to PSⅠactivity and the antioxidant system of PSⅠafter DCMU applied; Analyzed the relative enzyme in photosynthetic carbon assimilating to clarify the effect of light intensity and ozone stress on dark reactions; The expression of psbA gene, encoding D1 protein, were analyzed to study the light intensity and ozone stress on the inhibition of D1 repair; Meanwhile, photorespiration and xanthophyll cycle responses were analyzed to clarify the effect of light intensity and ozone stress on photoprotection pathways.Which completely reveal the synergistic effects of light and ozone stress on photosynthetic function in grapevine leaves, and provided theory basis of training system to alleviate ozone injury.

臭氧已超过PM2.5成为我国很多地区5~10月份首要环境污染因子。臭氧与光照协同产生的光氧化作用对植物伤害极大。本项目在前期进行了不同葡萄品种臭氧敏感性研究的基础上，利用臭氧发生室进行臭氧与光胁迫协同处理，探讨不同光强下发生臭氧伤害的臭氧浓度阈值；摸清臭氧与强光胁迫发生的先后顺序对气孔运动的影响；引入D1蛋白合成抑制剂氯霉素，测定PSⅡ活性、D1蛋白含量，摸清臭氧与强光协同处理对PSⅡ的破坏机制；引入敌草隆（DCMU）阻断PSII向PSI的电子传递，探讨臭氧胁迫对PSⅠ活性及PSⅠ活性氧清除系统的影响；分析光合碳同化相关酶/基因表达和光合同化产物积累，探讨协同胁迫对光合作用暗反应的影响。测定编码D1蛋白基因psbA 表达，探讨臭氧胁迫在抑制D1蛋白修复中的作用；分析光破坏防御途径光呼吸、叶黄素循环的响应，进而全面揭示臭氧与光协同作用对葡萄光合性能伤害机制，为调整架势缓解臭氧伤害提供理论依据

臭氧已超过PM2.5成为我国很多地区5-10月份首要环境污染因子。本项目旨在摸清不同光照强度下葡萄叶片发生伤害的臭氧浓度阈值，探明臭氧和光照协同胁迫对光合机能伤害及D1 蛋白修复和光破坏防御途径的影响。研究结果表明臭氧与光照对葡萄叶片协同胁迫产生光氧化作用，通过响应面设计建立了Fv/Fm（Y）与臭氧浓度A、光照强度B及其互作效应AB的模型方程Y=+0.73-0.034* A-0.022*B-0.018*A*B-5.163E-003*A2+8.375E-004*B2，根据此模型方程可确定不同光照强度下发生臭氧伤害的浓度及不同臭氧浓度下发生臭氧伤害的光照强度。明确了当叶片Fv/Fm值为0.711（叶片开始出现胁迫症状前的最大光化学效率值）时，临界光照强度为1222.93 μmol•m-2•s-1，臭氧浓度为117.43 nL • L-1，当光照强度或O3浓度单独或同时升高，都会造成PSII最大光化学效率值下降；不同栽培架式研究结果表明棚架较篱架缓解了臭氧胁迫对葡萄叶片的影响。由此提出通过监测臭氧浓度及光照强度，根据预警阈值进行遮阳网覆盖及在臭氧污染地区采用棚架栽培措施缓解臭氧胁迫的栽培技术，对生产具有重要的指导意义；超微结构结果表明，臭氧胁迫下，随光强增加，气孔开放程度逐渐降低，叶片叶绿体形状逐渐变圆，叶绿体膜逐渐变模糊溶解，基粒片层逐渐变形紊乱，淀粉粒逐渐减小；对光合性能研究结果表明，臭氧胁迫降低了光合同化的关键酶Rubisco活性，降低了葡萄叶片的光呼吸速率、羧化效率、用于碳同化的激发电子Je(PCR))和用于光呼吸的激发电子Je(PCO)。PSII和PSI都受到臭氧胁迫的影响。在臭氧胁迫下，PSII和PSI的结构蛋白PsbR，PsaK，PsaA表达下调可能是PSII (Y(II))显著降低的原因。臭氧胁迫下调了D1蛋白表达，抑制D1蛋白周转进而加剧PSⅡ的光破坏。臭氧胁迫上调叶黄素循环相关蛋白VDE 和 ZEP表达参与热耗散响应。臭氧胁迫导致了较高的ETRI-ETRII值并上调PGR5-like protein 1A 和NDH subunit of subcomplex B1蛋白表达，说明PGR途径和NDH途径的环式电子传递参与臭氧胁迫下的光破坏防御。这些结果为进一步深入研究葡萄应对臭氧胁迫的响应机制奠定了理论基础。