Gao Yanqiang, Zhang Jing, Wang Cheng, Han Kangning, Hu Lixia, Niu Tianhang, Yang Yan, Chang Youlin, Xie Jianming
College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China.
Plants (Basel). 2023 Feb 17;12(4):928. doi: 10.3390/plants12040928.
This study aimed to explore how exogenous proline induces salinity tolerance in celery. We analyzed the effects of foliar spraying with 0.3 mM proline on celery growth, photosystem, phenolic compounds, and antioxidant system under salt stress (100 mM NaCl), using no salt stress and no proline spraying as control. The results showed that proline-treated plants exhibited a significant increase in plant biomass due to improved growth physiology, supported by gas exchange parameters, chlorophyll fluorescence, and Calvin cycle enzyme activity (Ketosasaccharide-1,5-diphosphate carboxylase and Fructose-1,6-diphosphate aldolase) results. Also, proline spraying significantly suppressed the increase in relative conductivity and malondialdehyde content caused by salt stress, suggesting a reduction in biological membrane damage. Moreover, salt stress resulted in hydrogen peroxide, superoxide anions and 4-coumaric acid accumulation in celery, and their contents were reduced after foliar spraying of proline. Furthermore, proline increased the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and the content of non-enzymatic antioxidants (reduced ascorbic acid, glutathione, caffeic acid, chlorogenic acid, total phenolic acids, and total flavonoids). Additionally, proline increased the activity of key enzymes (ascorbate oxidase, ascorbate peroxidase, glutathione reductase, and dehydroascorbate reductase) in the ascorbic acid-glutathione cycle, activating it to counteract salt stress. In summary, exogenous proline promoted celery growth under salt stress, enhanced photosynthesis, increased total phenolic acid and flavonoid contents, and improved antioxidant capacity, thereby improving salt tolerance in celery.
本研究旨在探讨外源脯氨酸如何诱导芹菜的耐盐性。我们分析了在盐胁迫（100 mM NaCl）下，叶面喷施0.3 mM脯氨酸对芹菜生长、光系统、酚类化合物和抗氧化系统的影响，以无盐胁迫且未喷施脯氨酸作为对照。结果表明，脯氨酸处理的植株由于生长生理改善，生物量显著增加，这得到了气体交换参数、叶绿素荧光以及卡尔文循环酶活性（酮糖-1,5-二磷酸羧化酶和果糖-1,6-二磷酸醛缩酶）结果的支持。此外，喷施脯氨酸显著抑制了盐胁迫引起的相对电导率和丙二醛含量的增加，表明生物膜损伤减少。而且，盐胁迫导致芹菜中过氧化氢、超氧阴离子和对香豆酸积累，叶面喷施脯氨酸后其含量降低。此外，脯氨酸提高了抗氧化酶（超氧化物歧化酶、过氧化物酶和过氧化氢酶）的活性以及非酶抗氧化剂（还原型抗坏血酸、谷胱甘肽、咖啡酸、绿原酸、总酚酸和总黄酮）的含量。另外，脯氨酸提高了抗坏血酸-谷胱甘肽循环中关键酶（抗坏血酸氧化酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶和脱氢抗坏血酸还原酶）的活性，激活该循环以对抗盐胁迫。总之，外源脯氨酸在盐胁迫下促进了芹菜生长，增强了光合作用，增加了总酚酸和黄酮含量，并提高了抗氧化能力，从而提高了芹菜的耐盐性。
