Rising temperature is among the most remarkably stressful phenomena induced by global climate changes with negative impacts on crop productivity and quality. It has been previously shown that volatiles belonging to the isoprenoid family can confer protection against abiotic stresses. In this work, two Vitis vinifera cv. ‘Chardonnay’ clones (SMA130 and INRA809) differing due to a mutation (S272P) of the DXS gene encoding for 1-deoxy-D-xylulose-5-phosphate (the first dedicated enzyme of the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway) and involved in the regulation of isoprenoids biosynthesis were investigated in field trials and laboratory experiments. Leaf monoterpene emission, chlorophyll fluorescence and gas-exchange measurements were assessed over three seasons at different phenological stages and either carried out in in vivo or controlled conditions under contrasting temperatures. A significant (p < 0.001) increase in leaf monoterpene emission was observed in INRA809 when plants were experiencing high temperatures and over two experiments, while no differences were recorded for SMA130. Significant variation was observed for the rate of leaf CO₂ assimilation under heat stress, with INRA809 maintaining higher photosynthetic rates and stomatal conductance values than SMA130 (p = 0.003) when leaf temperature increased above 30 °C. At the same time, the maximum photochemical quantum yield of PSII (F_v/F_m) was affected by heat stress in the non-emitting clone (SMA130), while the INRA809 showed a significant resilience of PSII under elevated temperature conditions. Consistent data were recorded between field seasons and temperature treatments in controlled environment conditions, suggesting a strong influence of monoterpene emission on heat tolerance under high temperatures. This work provides further insights on the photoprotective role of isoprenoids in heat-stressed Vitis vinifera, and additional studies should focus on unraveling the mechanisms underlying heat tolerance on the monoterpene-emitter grapevine clone.

中文翻译：

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田间生长的葡萄叶片单萜排放限制了热胁迫下的光合作用下调

温度升高是全球气候变化引起的最显着的压力现象之一，对作物的生产力和质量产生负面影响。先前已经表明，属于类异戊二烯家族的挥发物可以赋予针对非生物胁迫的保护。在这项工作中，两个葡萄简历。“霞多丽”克隆（SMA130和INRA809）由于编码1-脱氧-D-木酮糖-5-磷酸（2C-甲基-D-赤藓醇-4的第一个专用酶）的DXS基因的突变（S272P）而有所不同-磷酸盐（MEP）途径）和参与类异戊二烯生物合成的调控已在现场试验和实验室实验中进行了研究。在三个季节的不同物候阶段评估叶片单萜的排放，叶绿素荧光和气体交换测量，并在不同温度下在体内或受控条件下进行。显着性（p当植物处于高温和两个实验中时，在INRA809中观察到叶片单萜的排放增加（<0.001），而SMA130没有记录到差异。观察到在热胁迫下叶片CO ₂同化速率有显着变化，当叶片温度升高到30°C以上时，INRA809保持高于SMA130的光合作用速率和气孔导度值（p = 0.003）。同时，PSII的最大光化学量子产率（F _v / F _m）受非发光克隆（SMA130）中热应激的影响，而INRA809在高温条件下显示出显着的PSII弹性。在田间季节和受控环境条件下的温度处理之间记录了一致的数据，表明单萜类化合物的排放对高温下的耐热性有很大影响。这项工作提供了关于类异戊二烯在热胁迫的葡萄中的光保护作用的进一步见解，另外的研究应集中于揭示单萜-发射体葡萄克隆的耐热性基础。