College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural University, Suqian, 223800, China.
College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
Plant Physiol Biochem. 2020 Nov;156:333-344. doi: 10.1016/j.plaphy.2020.09.010. Epub 2020 Sep 12.
Transglutaminase (TGase) is inextricably associated with plant growth and development. However, the mechanism by which TGase enhances salt tolerance of higher plants under salt stress is poorly understood. In this study, we investigated the effects of NaCl stress and exogenous o-phenanthroline (o-Phen, a metalloprotease inhibitor) on TGase activity, chlorophyll fluorescence parameters, carbohydrates contents, the reactive oxygen species (ROS) scavenging system, and endogenous polyamines (PAs) contents of salt-sensitive 'Jinyou No. 4' and salt-tolerant 'Inbred Line 9930' cucumber. Salt stress significantly inhibited plant growth of the two cultivars, as well as hindered carbohydrates transport, which was more evident in the salt-sensitive cultivar. TGase activity and expression, ROS scavenging capacity, and bound PAs content were up-regulated by salt stress to some extent, which was more distinct in the salt-tolerant cucumber cultivar. However, o-Phen treatment significantly inhibited TGase expression, and further decreased plant growth and the actual photochemical efficiency of photosystem II in the two cultivars. In addition, application of o-Phen significantly decreased endogenous PAs content in leaves of 'Jinyou No. 4' and 'Inbred Line 9930' seedlings by 9.60% and 42.32% under NaCl stress, respectively. These results suggested that high activity of TGase increases the salt stress tolerance of cucumber plants by increasing endogenous PAs content and ROS scavenging capacity, and promoting carbon assimilation and photosynthetic products.
转谷氨酰胺酶（TGase）与植物的生长和发育密切相关。然而，在盐胁迫下，TGase 增强高等植物耐盐性的机制还不清楚。在这项研究中，我们研究了 NaCl 胁迫和外源性邻菲啰啉（o-Phen，一种金属蛋白酶抑制剂）对 TGase 活性、叶绿素荧光参数、碳水化合物含量、活性氧（ROS）清除系统和内源性多胺（PAs）含量的影响盐敏感型‘金优 4 号’和耐盐型‘自交系 9930’黄瓜。盐胁迫显著抑制了两个品种的植物生长，同时阻碍了碳水化合物的运输，在盐敏感品种中更为明显。TGase 活性和表达、ROS 清除能力以及结合态 PAs 含量在一定程度上被盐胁迫上调，在耐盐性黄瓜品种中更为明显。然而，o-Phen 处理显著抑制了 TGase 的表达，进一步降低了两个品种的植物生长和光系统 II 的实际光化学效率。此外，在 NaCl 胁迫下，o-Phen 的应用分别使‘金优 4 号’和‘自交系 9930’幼苗叶片中的内源 PAs 含量降低了 9.60%和 42.32%。这些结果表明，高活性的 TGase 通过增加内源 PAs 含量和 ROS 清除能力，促进碳同化和光合产物，提高黄瓜植株的耐盐性。
