Table_1_Acetic Acid Treatment Enhances Drought Avoidance in Cassava (Manihot esculenta Crantz).XLSX

The external application of acetic acid has recently been reported to enhance survival of drought in plants such as Arabidopsis, rapeseed, maize, rice, and wheat, but the effects of acetic acid application on increased drought tolerance in woody plants such as a tropical crop “cassava” remain elusive. A molecular understanding of acetic acid-induced drought avoidance in cassava will contribute to the development of technology that can be used to enhance drought tolerance, without resorting to transgenic technology or advancements in cassava cultivation. In the present study, morphological, physiological, and molecular responses to drought were analyzed in cassava after treatment with acetic acid. Results indicated that the acetic acid-treated cassava plants had a higher level of drought avoidance than water-treated, control plants. Specifically, higher leaf relative water content, and chlorophyll and carotenoid levels were observed as soils dried out during the drought treatment. Leaf temperatures in acetic acid-treated cassava plants were higher relative to leaves on plants pretreated with water and an increase of ABA content was observed in leaves of acetic acid-treated plants, suggesting that stomatal conductance and the transpiration rate in leaves of acetic acid-treated plants decreased to maintain relative water contents and to avoid drought. Transcriptome analysis revealed that acetic acid treatment increased the expression of ABA signaling-related genes, such as OPEN STOMATA 1 (OST1) and protein phosphatase 2C; as well as the drought response and tolerance-related genes, such as the outer membrane tryptophan-rich sensory protein (TSPO), and the heat shock proteins. Collectively, the external application of acetic acid enhances drought avoidance in cassava through the upregulation of ABA signaling pathway genes and several stress responses- and tolerance-related genes. These data support the idea that adjustments of the acetic acid application to plants is useful to enhance drought tolerance, to minimize the growth inhibition in the agricultural field.

近期有研究报道，外源施用乙酸可提升拟南芥、油菜、玉米、水稻及小麦等植物的干旱存活能力，但针对木本热带作物木薯，乙酸施用对其抗旱性增强的具体作用仍尚不明确。解析木薯中乙酸诱导的避旱机制，有助于开发无需借助转基因技术或木薯栽培改良即可提升其抗旱性的相关技术。本研究对乙酸处理后的木薯在干旱胁迫下的形态、生理及分子响应进行了分析。结果显示，经乙酸处理的木薯植株较清水处理的对照组植株具有更强的避旱能力。具体而言，在干旱处理过程中土壤逐渐失水时，乙酸处理组木薯的叶片相对含水量、叶绿素及类胡萝卜素水平均显著高于对照组。与清水预处理的对照组相比，乙酸处理组木薯的叶片温度更高，且叶片中脱落酸（ABA）含量显著升高，这表明乙酸处理组植株的叶片气孔导度与蒸腾速率有所降低，从而维持叶片相对含水量以实现避旱。转录组分析结果显示，乙酸处理上调了脱落酸信号通路相关基因的表达，例如气孔开放因子1（OPEN STOMATA 1, OST1）与蛋白磷酸酶2C；同时也上调了干旱响应及抗旱相关基因的表达，例如外膜富色氨酸传感蛋白（TSPO）以及热激蛋白家族基因。综上，外源施用乙酸可通过上调脱落酸信号通路基因以及多种胁迫响应与抗旱相关基因的表达，提升木薯的避旱能力。本研究数据表明，优化植物的乙酸施用方案可有效提升作物抗旱性，进而减轻农业生产中干旱胁迫导致的生长抑制。