Salicylic acid and proline modulate water stress tolerance in a traditional variety of cowpeas

ABSTRACT Exogenous applications of chemical compounds stimulate changes in plant metabolism and promote tolerance to different environmental stresses, including water deficit. This study aimed to evaluate the ability of salicylic acid (SA) and proline (PRO) to reduce water stress in a traditional variety of cowpea in a typical Brazilian semiarid climate. A completely randomized design was used in a 2 × 4 factorial scheme, with five replicates. Two irrigation regimes were evaluated corresponding to 100% (W100) and 50% of daily evapotranspiration (W50), respectively, with the addition of the following four attenuators: control (distilled water), SA (550 mg L-1), PRO (690 mg L-1), and 690 mg L-1 PRO + 550 mg L-1 SA. The treatments promoted changes in osmotic and antioxidant metabolism, which may contribute to the tolerance mechanisms of cowpea plants to water stress. The application of SA increased osmoregulator synthesis and protein concentrations, and modulated antioxidant enzyme activity in the cowpea plants under water stress. PRO concentrations increased synergistically in plants treated with PRO and SA, particularly in 50% of water replacement.

摘要：外源性施用化学物质可诱导植物代谢发生改变，并提升其对包括水分亏缺在内的多种环境胁迫的耐受能力。本研究旨在评估水杨酸（salicylic acid, SA）与脯氨酸（proline, PRO）在巴西典型半干旱气候下，缓解传统豇豆品种水分胁迫的效能。实验采用完全随机设计，设置2×4因子组合，共5次重复。设置两种灌溉制度，分别对应每日蒸散量的100%（W100）与50%（W50），并添加4种胁迫缓解剂：对照组（蒸馏水）、550 mg·L⁻¹水杨酸（SA）、690 mg·L⁻¹脯氨酸（PRO），以及690 mg·L⁻¹脯氨酸与550 mg·L⁻¹水杨酸的复合处理组。各处理均对渗透调节与抗氧化代谢产生调控作用，或可参与豇豆植株应对水分胁迫的耐受机制。施加水杨酸可提升水分胁迫下豇豆植株的渗透调节物质合成水平与蛋白浓度，并调控其抗氧化酶活性。单独施用脯氨酸或与水杨酸复配时，植株体内脯氨酸浓度呈协同升高趋势，尤其在50%灌溉量处理组中表现更为显著。