Responses of photosystem II photochemistry and the alternative oxidase pathway to heat stress in grape leaves

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• 作者：Yongjiang Sun ; Xiaohong Liu ; Heng Zhai ; Huiyuan Gao…
• 关键词：Heat stress ; Photoinhibition ; AOX ; Grapevine
• 刊名：Acta Physiologiae Plantarum
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：38
• 期：10
• 全文大小：682 KB
• 刊物主题：Plant Physiology; Plant Genetics & Genomics; Plant Biochemistry; Plant Pathology; Plant Anatomy/Development; Agriculture;
• 出版者：Springer Berlin Heidelberg
• ISSN：1861-1664
• 卷排序：38

文摘

To study the photochemical responses of photosystem II (PSII) and mitochondrial alternative oxidase (AOX) to heat stress in grapevine (Vitis vinifera L. cv. ‘Cabernet Sauvignon’), we exposed grape leaves to a range of temperatures (25, 30, 35, 40, and 42.5 °C) in the light (600 µmol m−2 s−1). At temperatures >35 °C, the rate of photosynthetic O₂ evolution and the maximal photochemistry efficiency of PSII (F_v/F_m) decreased significantly. We observed that the relative variable fluorescence increased at the J step, and there was also an accumulation of H₂O₂. In addition, there was an increase in both the non-photochemical quenching (NPQ) and the capacity of the alternative oxidase pathway (AOX) at higher temperatures. When the leaves were treated with the AOX inhibitor salicylhydroxamic acid, a significant decrease in the PSII electron transport rate and NPQ and an increase in H₂O₂ content occurred. Our results suggest that high temperature limits electron transport beyond Q_A−, resulting in a strong accumulation of H₂O₂ in grape leaves. Inhibition of the AOX pathway increases the formation and accumulation of H₂O₂ in grape leaves, and may thereby increase photoinhibition in leaves experiencing heat stress.