Abstract Rising air CO2 concentration ([CO2]) is believed to mitigate the negative impacts of global climate changes such as increased air temperatures and drought events on plant growth and survival. Nonetheless, how elevated [CO2] affects the way coffee (Coffea arabica L.) plants sense and respond to drought remains a critical unknown. In this study, potted coffee plants were cultivated under two air [CO2] (ca. 400 ppm or 700 ppm) in open top chambers under greenhouse conditions. After a 5-month exposure to [CO2] treatments, plants were submitted to a progressive, controlled soil water deficit down to 20 % soil field capacity. Under well-watered (100 % field capacity) conditions, 700-plants displayed lower whole-plant transpiration rates (T) than their 400-counterparts. Changes in T were unrelated to stomatal conductances at the leaf scale (as well as stomatal morphology) or foliar ABA levels, but they were rather associated with faster stomata closure rates upon rapid increases in vapor pressure deficit in the 700-plants. During drought, 700-plants were able to maintain higher water potentials and plant hydraulic conductances for longer in parallel to higher T than their 400-counterparts. Under elevated [CO2], the faster stomatal closure rates (irrigated conditions) or the maintenance of plant hydraulic conductances (drought conditions) were associated with higher (3 to 40-fold) transcript abundance of most aquaporin genes. Altogether, our results suggest that elevated [CO2] has marked implications on how coffee plants respond to soil water deficit, ultimately permitting 700-plants to have improved fitness under drought when compared to 400-plants.

中文翻译：

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咖啡植物通过气孔功能、植物水力传导和水通道蛋白表达的变化来应对干旱和 [CO2] 升高

摘要 空气中二氧化碳浓度 ([CO2]) 的升高被认为可以减轻全球气候变化的负面影响，例如气温升高和干旱事件对植物生长和生存的负面影响。尽管如此，[CO2] 升高如何影响咖啡（Coffea arabica L.）植物感知和应对干旱的方式仍然是一个关键的未知数。在这项研究中，盆栽咖啡植物在温室条件下在开放式顶室中在两种空气 [CO2]（约 400 ppm 或 700 ppm）下栽培。经过 5 个月的 [CO2] 处理后，植物逐渐处于受控的土壤缺水状态，土壤水分亏缺降至 20% 的土壤田间容量。在充分浇水（100% 田间容量）条件下，700 株植物的全株蒸腾速率 (T) 低于 400 株植物。T 的变化与叶尺度（以及气孔形态）或叶面 ABA 水平的气孔导度无关，但它们与 700 株植物中蒸气压不足迅速增加时更快的气孔关闭率相关。在干旱期间，与 400 株植物相比，700 株植物能够保持更高的水势和植物水力传导率，同时与更高的 T 平行。在 [CO2] 升高的情况下，更快的气孔关闭速率（灌溉条件）或植物水力传导的维持（干旱条件）与大多数水通道蛋白基因的转录本丰度更高（3 到 40 倍）有关。总而言之，我们的结果表明，升高的 [CO2] 对咖啡植物如何应对土壤缺水具有显着影响，