ABSTRACT

To probe the mechanism of action of NaCl in regulating drought adaptation in Medicago sativa, we pretreated M. sativa with different concentrations (0, 50, 100 and 200 mM) of NaCl, then studied the effects of NaCl pretreatment on water content, chlorophyll content, photosynthetic function, and membrane peroxidation of M. sativa plants subjected to drought stress. Although pretreatment with different concentrations of NaCl significantly increased the Na⁺ content in the aboveground of M. sativa, it had no significant effect on the activity of PSII and PSI. However, different concentrations of NaCl pretreatment significantly increased the water content of the aboveground of M. sativa under drought stress, alleviated the degree of photoinhibition of PSII and PSI, and maintained the flow and stability of donor and acceptor electrons in PSII. NaCl pretreatment promotes the increase of non-photochemical quenching (NPQ), which relieves oxidative damage in the leaves of M. sativa under drought stress, playing an important role in maintaining the activity of PSII and PSI. In conclusion, pretreatment with a certain concentration of NaCl can help M. sativa leaves maintain relatively high-water content and alleviate the photosynthesis inhibition of PSII and PSI under drought stress, thereby improving the drought resistance of M. sativa.

摘要

为了探讨氯化钠在调节紫花苜蓿干旱适应中的作用机理，我们用不同浓度（0、50、100和200 mM）的氯化钠对苜蓿进行了预处理，然后研究了氯化钠预处理对水分，叶绿素含量的影响。干旱胁迫下苜蓿植株的光合作用，光合功能和膜过氧化 尽管用不同浓度的NaCl预处理显着增加了苜蓿地上部分的Na ⁺含量，但对PSII和PSI的活性没有明显影响。然而，不同浓度的氯化钠预处理显着增加了苜蓿地上部分的水分含量。在干旱胁迫下，减轻了PSII和PSI的光抑制程度，并维持了PSII中供体和受体电子的流动和稳定性。NaCl预处理可促进非光化学猝灭（NPQ）的增加，从而减轻干旱胁迫下紫花苜蓿叶片的氧化损伤，在维持PSII和PSI的活性中起重要作用。综上所述，用一定浓度的NaCl预处理可以帮助紫花苜蓿叶片保持较高的水分含量，减轻干旱胁迫下PSII和PSI的光合作用抑制，从而提高紫花苜蓿的抗旱性。