Shu Sheng, Tang Yuanyuan, Yuan Yinghui, Sun Jin, Zhong Min, Guo Shirong
College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China; Facility Horticulture Institute, Nanjing Agricultural University, Suqian 223800, People's Republic of China.
College of Horticulture, Nanjing Agricultural University, Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, People's Republic of China.
Plant Physiol Biochem. 2016 Oct;107:344-353. doi: 10.1016/j.plaphy.2016.06.021. Epub 2016 Jun 16.
In the present study, we aimed to investigate the effects of exogenous 24-epibrassinolide (EBR) on growth, photosynthetic characteristics, chlorophyll fluorescence imaging, and nitrogen metabolism of tomato leaves under low temperature and weak light conditions. The results showed that foliar application of EBR significantly alleviated the inhibition of plant growth, and increased the fresh and dry weights of tomato plants under a combined low temperature and weak light stress. Moreover, EBR also increased the net photosynthetic rate (Pn), light saturation point (LSP), maximal quantum yield of PSII photochemistry (Fv/Fm), actual photochemical efficiency of PSII (ФPSII), and photochemical quenching coefficient (qP), but decreased the intercellular CO2 concentration (Ci), light compensation point (LCP) and apparent quantum efficiency (AQE) under low temperature and weak light conditions. In addition, application of EBR to tomato leaves significantly enhanced the activities of nitrate reductase (NR), glutamate dehydrogenase (GDH), glutamine synthetase (GS), and glutamate synthase (GOGAT), but decreased the ammonium content and nitrite reductase (NiR) activity. We observed that EBR remarkably increased the contents of aspartic acid, threonine, serine, glycine, and phenylalanine, while decreasing the accumulation of cysteine, methionine, arginine, and proline under a combined low temperature and light stress. These results suggest that EBR could alleviate the combined stress-induced harmful effects on photosynthesis and nitrogen metabolism, thus leading to improved plant growth.
在本研究中，我们旨在探究外源24-表油菜素内酯（EBR）对低温弱光条件下番茄叶片生长、光合特性、叶绿素荧光成像及氮代谢的影响。结果表明，叶面喷施EBR显著缓解了植物生长受到的抑制，增加了低温弱光复合胁迫下番茄植株的鲜重和干重。此外，EBR还提高了低温弱光条件下的净光合速率（Pn）、光饱和点（LSP）、PSII光化学最大量子产量（Fv/Fm）、PSII实际光化学效率（ФPSII）和光化学猝灭系数（qP），但降低了胞间CO2浓度（Ci）、光补偿点（LCP）和表观量子效率（AQE）。另外，对番茄叶片施用EBR显著提高了硝酸还原酶（NR）、谷氨酸脱氢酶（GDH）、谷氨酰胺合成酶（GS）和谷氨酸合酶（GOGAT）的活性，但降低了铵含量和亚硝酸还原酶（NiR）的活性。我们观察到，在低温弱光复合胁迫下，EBR显著增加了天冬氨酸、苏氨酸、丝氨酸、甘氨酸和苯丙氨酸的含量，同时减少了半胱氨酸、蛋氨酸、精氨酸和脯氨酸的积累。这些结果表明，EBR可以缓解复合胁迫对光合作用和氮代谢的有害影响，从而促进植物生长。
