Celery is a vegetable crop with rich nutrition and economic value. It is easy to be affected by abiotic stress in its cultivation. Ascorbate (AsA) is considered as an important nutrient component in vegetable crops and an antioxidant for plants against abiotic stress. Dehydroascorbate reductase (DHAR) is a critical enzyme involved in AsA recycling. The study on the characteristics and functions of DHAR in celery were limited to date. Here, we identified a gene, AgDHAR2, encoding dehydroascorbate reductase from celery. AgDHAR2 was a chloroplast-localized protein and belonged to the member of glutathione S-transferases (GSTs) with conserved GST_N_3 and GST_C_2 domains. Transcript level of AgDHAR2 and the AsA accumulation in celery cvs. ‘Jinnan Shiqin’ and ‘Huangtaiji’ were induced under diverse stress conditions. Transgenic Arabidopsis thaliana and celery plants transformed with AgDHAR2 were generated to further investigate its role in AsA accumulation and drought stress response. Overexpression of AgDHAR2 in A. thaliana and celery led to elevated AsA contents and up-regulated AsA:DHA ratio. When subjected to drought stress, the progeny of transgenic A. thaliana plants hosting AgDHAR2 gene exhibited improved antioxidant-related genes expression, SOD and POD activities, proline accumulation and plant survival rates compared with wild-type plants, thereby showing higher drought tolerance. Taken together, the results of this study demonstrated that AgDHAR2 might contribute to enhanced drought tolerance through increasing AsA concentrations and maintaining redox state in celery.

芹菜是一种营养丰富且具有经济价值的蔬菜作物。其栽培中易受非生物胁迫的影响。抗坏血酸 (AsA) 被认为是蔬菜作物的重要营养成分和植物抗非生物胁迫的抗氧化剂。脱氢抗坏血酸还原酶 (DHAR) 是参与 AsA 回收的关键酶。迄今为止，关于芹菜中DHAR的特性和功能的研究有限。在这里，我们鉴定了一个基因AgDHAR2，它编码芹菜中的脱氢抗坏血酸还原酶。AgDHAR2 是一种叶绿体定位蛋白，属于具有保守 GST_N_3 和 GST_C_2 结构域的谷胱甘肽S-转移酶 (GST) 成员。AgDHAR2的转录水平和芹菜 cvs 中的 AsA 积累。在不同的胁迫条件下诱导了'金南石琴'和'皇太极'。生成了用AgDHAR2转化的转基因拟南芥和芹菜植物，以进一步研究其在 AsA 积累和干旱胁迫响应中的作用。拟南芥和芹菜中AgDHAR2的过表达导致 AsA 含量升高和 AsA:DHA 比率上调。当受到干旱胁迫时，携带 AgDHAR2的转基因拟南芥植物的后代与野生型植物相比，该基因表现出更高的抗氧化相关基因表达、SOD和POD活性、脯氨酸积累和植物存活率，从而表现出更高的耐旱性。总之，这项研究的结果表明，AgDHAR2可能通过增加 AsA 浓度和维持芹菜中的氧化还原状态来增强耐旱性。