ABSTRACT

The effects of exogenous γ-glutamic acid (GABA) on photosynthetic gas exchange capacity, PSII function, proline (Pro) synthesis and ROS metabolism of tobacco leaves under cadmium (Cd) stress were studied. The results showed that both stomatal and non-stomatal factors were the important factors to limit the photosynthetic capacity of tobacco leaves under Cd stress. Pro accumulation and glutathione (GSH) content increase are the important ways for tobacco leaves to adapt to Cd stress. Exogenous GABA significantly increased the stability of oxygen-evolving complex (OEC) and the electron transfer rate of PSII in tobacco leaves under Cd stress, and increased G_s and P_n in varying degrees. Exogenous GABA also increased the expression of P5CS and P5CR genes in tobacco leaves under Cd stress, thus promoting Pro accumulation. In conclusion, 0.5 mmol·L⁻¹ exogenous GABA can not only improve the carbon assimilation ability by increasing the G_s, but also alleviate the oxidative damage by promoting the synthesis and accumulation of Pro and GSH, and improve the stability of photosynthetic function of tobacco leaves under Cd stress.

摘要

研究了外源γ-谷氨酸(GABA)对镉(Cd)胁迫下烟叶光合气体交换能力、PSII功能、脯氨酸(Pro)合成和ROS代谢的影响。结果表明，气孔和非气孔因素都是限制镉胁迫下烟叶光合能力的重要因素。Pro积累和谷胱甘肽（GSH）含量增加是烟叶适应Cd胁迫的重要途径。外源GABA显着提高了Cd胁迫下烟叶中析氧复合物（OEC）的稳定性和PSII的电子转移速率，并不同程度地提高了G _s和P _n。外源性 GABA 也增加了P5CS的表达和P5CR基因在 Cd 胁迫下的烟叶中，从而促进 Pro 的积累。综上所述，0.5 mmol·L ^-1外源GABA不仅可以通过增加G _s来提高碳同化能力，还可以通过促进Pro和GSH的合成和积累减轻氧化损伤，提高光合功能的稳定性。镉胁迫下的烟叶。