Iqbal Nasir, Hussain Sajad, Raza Muhammad Ali, Yang Cai-Qiong, Safdar Muhammad Ehsan, Brestic Marian, Aziz Ahsan, Hayyat Muhammad Sikander, Asghar Muhammad Ahsan, Wang Xiao Chun, Zhang Jing, Yang Wenyu, Liu Jiang
Key Laboratory of Crop Ecophysiology and Farming System in Southwest, Ministry of Agriculture, College of Agronomy, Sichuan Agricultural University, Chengdu, China.
Department of Agronomy, College of Agriculture, University of Sargodha, Sargodha, Pakistan.
Front Physiol. 2019 Jul 3;10:786. doi: 10.3389/fphys.2019.00786. eCollection 2019.
Water deficiency significantly affects photosynthetic characteristics. However, there is little information about variations in antioxidant enzyme activities and photosynthetic characteristics of soybean under imbalanced water deficit conditions (WDC). We therefore investigated the changes in photosynthetic and chlorophyll fluorescence characteristics, total soluble protein, Rubisco activity (RA), and enzymatic activities of two soybean varieties subjected to four different types of imbalanced WDC under a split-root system. The results indicated that the response of both cultivars was significant for all the measured parameters and the degree of response differed between cultivars under imbalanced WDC. The maximum values of enzymatic activities (SOD, CAT, GR, APX, and POD), chlorophyll fluorescence (Fv/Fm, qP, ɸPSII, and ETR), proline, RA, and total soluble protein were obtained with a drought-tolerant cultivar (ND-12). Among imbalanced WDC, the enhanced net photosynthesis, transpiration, and stomatal conductance rates in T2 allowed the production of higher total soluble protein after 5 days of stress, which compensated for the negative effects of imbalanced WDC. Treatment T4 exhibited greater potential for proline accumulation than treatment T1 at 0, 1, 3, and 5 days after treatment, thus showing the severity of the water stress conditions. In addition, the chlorophyll fluorescence values of FvFm, ɸPSII, qP, and ETR decreased as the imbalanced WDC increased, with lower values noted under treatment T4. Soybean plants grown in imbalanced WDC (T2, T3, and T4) exhibited signs of oxidative stress such as decreased chlorophyll content. Nevertheless, soybean plants developed their antioxidative defense-mechanisms, including the accelerated activities of these enzymes. Comparatively, the leaves of soybean plants in T2 displayed lower antioxidative enzymes activities than the leaves of T4 plants showing that soybean plants experienced less WDC in T2 compared to in T4. We therefore suggest that appropriate soybean cultivars and T2 treatments could mitigate abiotic stresses under imbalanced WDC, especially in intercropping.
水分亏缺显著影响光合特性。然而，关于大豆在不平衡水分亏缺条件（WDC）下抗氧化酶活性和光合特性的变化，相关信息较少。因此，我们在分根系统下，研究了两个大豆品种在四种不同类型的不平衡WDC处理下，光合和叶绿素荧光特性、总可溶性蛋白、核酮糖-1,5-二磷酸羧化酶活性（RA）以及酶活性的变化。结果表明，两个品种对所有测量参数的响应均显著，且在不平衡WDC条件下，不同品种的响应程度存在差异。耐旱品种（ND-12）的酶活性（超氧化物歧化酶、过氧化氢酶、谷胱甘肽还原酶、抗坏血酸过氧化物酶和过氧化物酶）、叶绿素荧光（Fv/Fm、qP、ɸPSII和ETR）、脯氨酸、RA和总可溶性蛋白的最大值均较高。在不平衡WDC中，T2处理下增强的净光合速率、蒸腾速率和气孔导度，使得胁迫5天后能够产生更高的总可溶性蛋白，从而补偿了不平衡WDC的负面影响。处理T4在处理后0、1、3和5天比处理T1表现出更大的脯氨酸积累潜力，从而表明水分胁迫条件的严重性。此外，随着不平衡WDC的增加，FvFm、ɸPSII、qP和ETR的叶绿素荧光值降低，在处理T4下的值更低。生长在不平衡WDC（T2、T3和T4）中的大豆植株表现出氧化应激迹象，如叶绿素含量降低。然而，大豆植株也发展出了抗氧化防御机制，包括这些酶活性的加速。相比之下，T2处理下大豆植株叶片的抗氧化酶活性低于T4处理下的叶片，这表明与T4相比，T2处理下大豆植株经历的水分亏缺更少。因此，我们建议，合适的大豆品种和T2处理可以减轻不平衡WDC下的非生物胁迫，特别是在间作中。
