1. Academic Validation
  2. Melatonin Positively Regulates Both Dark- and Age-Induced Leaf Senescence by Reducing ROS Accumulation and Modulating Abscisic Acid and Auxin Biosynthesis in Cucumber Plants

Melatonin Positively Regulates Both Dark- and Age-Induced Leaf Senescence by Reducing ROS Accumulation and Modulating Abscisic Acid and Auxin Biosynthesis in Cucumber Plants

  • Int J Mol Sci. 2022 Mar 25;23(7):3576. doi: 10.3390/ijms23073576.
Tongtong Jing 1 Kun Liu 1 Yanan Wang 1 Xizhen Ai 1 Huangai Bi 1
Affiliations

Affiliation

  • 1 State Key Laboratory of Crop Biology, Key Laboratory of Crop Biology and Genetic Improvement of Horticultural Crops in Huanghuai Region, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an 271018, China.
Abstract

Melatonin (MT), as a signaling molecule, plays a vital role in regulating leaf senescence in Plants. This study aimed to verify the antioxidant roles of MT in delaying dark- or age-induced leaf senescence of cucumber Plants. The results showed that endogenous MT responds to darkness and overexpression of CsASMT, the key gene of MT synthesis, and delays leaf senescence stimulated by darkness, as manifested by significantly lower malonaldehyde (MDA) and Reactive Oxygen Species (ROS) contents as well as higher activities and gene expression of antioxidant Enzymes compared to the control. Moreover, MT suppressed both age- or dark-induced leaf senescence of cucumber, as evidenced by a decrease in senescence-related gene SAG20 and cell-death-related gene PDCD expression and ROS content and an increase in antioxidant capacity and chlorophyll biosynthesis compared with the H2O-treated seedlings. Meanwhile, the suppression of age-induced leaf senescence by melatonin was also reflected by the reduction in Abscisic acid (ABA) biosynthesis and signaling pathways as well as the promotion of Auxin (IAA) biosynthesis and signaling pathways in cucumber Plants in the solar greenhouse. Combining the results of the two separate experiments, we demonstrated that MT acts as a powerful antioxidant to alleviate leaf senescence by activating the antioxidant system and IAA synthesis and signaling while inhibiting ABA synthesis and signaling in cucumber Plants.

Keywords

abscisic acid; antioxidant system; auxin; cucumber; leaf senescence; melatonin.

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