褪黑素通过调节棉花（Gossypium hirsutum L.）中的 ABA 和 GA 促进种子在盐胁迫下的萌发。

Melatonin promotes seed germination under salt stress by regulating ABA and GA in cotton (Gossypium hirsutum L.).

机构信息

State Key Laboratory of North China Crop Improvement and Regulation/College of Life Science, Hebei Agricultural University, Baoding, 071001, China; State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Crop Growth Regulation of Hebei Province/College of Agronomy, Hebei Agricultural University, Baoding, 071001, China.

College of Landscape and Tourism, Hebei Agricultural University, Baoding 071001, China.

出版信息

Plant Physiol Biochem. 2021 May;162:506-516. doi: 10.1016/j.plaphy.2021.03.029. Epub 2021 Mar 19.

DOI:10.1016/j.plaphy.2021.03.029

PMID:33773227

Abstract

Although previous studies have found that melatonin can promote seed germination, the phytohormone regulation mechanism by which exogenous melatonin mediates salt tolerance during cotton seed germination is still largely unknown. The effects of melatonin on germination traits and physiological parameters of GXM9 cotton seeds (Gossypium hirsutum L.) under three salt stress treatments (CK, germination of seeds pretreated with water alone; S, germination of seeds pretreated in 150 mM NaCl under salt stress; SM, germination of seeds pretreated in 20 μM melatonin under 150 mM NaCl solution) in the laboratory was investigated. The results showed that salt stress (150 mM) inhibited cotton seed germination and endogenous melatonin accumulation, and pretreatment with 20 μM exogenous melatonin enhanced the cotton germination rate and hypocotyl length as well as the content of endogenous melatonin during seed germination. This suggests that exogenous melatonin promotes seed germination from a morphological perspective. The contents of starch, α-amylase (EC3.3.1.1), β-galactosidase (EC3.2.1.23), abscisic acid (ABA), and gibberellin (GA) were determined simultaneously. The results showed that the α-amylase and β-galactosidase contents in the cotton seeds decreased by 56.97% and 20.18%, respectively, under salt stress compared with the control, while the starch content increased by 11.53% compared with the control at day 7. The ABA content increased by 25.18% and GA content decreased by 27.99% under salt stress compared with the control at 24 h. When exogenous melatonin was applied to the cotton seeds, the content of α-amylase and β-galactosidase increased by 121.77% and 32.76%, respectively, whereas the starch contents decreased by 13.55% compared with the S treatment at day 7. Similarly, the ABA content increased by 12.20% and the GA content increased by 4.77% at 24 h. To elucidate the molecular mechanism by which melatonin promotes seed germination under salt stress, the effects of ABA- and GA-related genes on plant hormone signal transduction were analyzed by quantitative real-time PCR and RNA sequencing. The results indicated that melatonin regulated the expression of ABA and GA genes in the plant signal transduction pathway, induced embryo root development and seed germination, and alleviated dormancy. The expression of the ABA signaling gene GhABF2 was up-regulated and GhDPBF2 was down-regulated, and the expression of GA signaling genes (e.g., GhGID1C and GhGID1B) was up-regulated by melatonin. In conclusion, melatonin enhances salt tolerance in cotton seeds by regulating ABA and GA and by mediating the expression of hormone-related genes in plant hormone signal transduction. This should help us to explore the regulatory mechanisms of cotton resistance and provide a foundation for the cultivation of new varieties.

摘要

虽然先前的研究发现褪黑素可以促进种子发芽，但外源褪黑素通过何种植物激素调节机制介导棉花种子发芽过程中的耐盐性还知之甚少。本研究在实验室条件下，采用三种盐胁迫处理（CK：单独用水预处理种子发芽；S：在 150 mM NaCl 溶液中用盐预处理种子发芽；SM：在 20 μM 褪黑素溶液中用盐预处理种子发芽），研究了外源褪黑素对 GXM9 棉花种子（Gossypium hirsutum L.）发芽特性和生理参数的影响。结果表明，盐胁迫（150 mM）抑制了棉花种子的发芽和内源褪黑素的积累，而 20 μM 外源褪黑素预处理提高了种子发芽率和下胚轴长度，以及种子发芽过程中内源褪黑素的含量。这表明外源褪黑素从形态学上促进了种子发芽。同时测定了淀粉、α-淀粉酶（EC3.3.1.1）、β-半乳糖苷酶（EC3.2.1.23）、脱落酸（ABA）和赤霉素（GA）的含量。结果表明，与对照相比，盐胁迫下棉花种子的α-淀粉酶和β-半乳糖苷酶含量分别下降了 56.97%和 20.18%，而淀粉含量在第 7 天与对照相比增加了 11.53%。与对照相比，盐胁迫下 ABA 含量增加了 25.18%，GA 含量下降了 27.99%，在 24 h 时。当外源褪黑素应用于棉花种子时，α-淀粉酶和β-半乳糖苷酶的含量分别增加了 121.77%和 32.76%，而淀粉含量在第 7 天与 S 处理相比下降了 13.55%。同样，ABA 含量增加了 12.20%，GA 含量增加了 4.77%，在 24 h 时。为了阐明褪黑素在盐胁迫下促进种子发芽的分子机制，通过定量实时 PCR 和 RNA 测序分析了与 ABA 和 GA 相关的基因对植物激素信号转导的影响。结果表明，褪黑素调节了植物信号转导途径中 ABA 和 GA 基因的表达，诱导了胚根的发育和种子的发芽，从而缓解了休眠。ABA 信号基因 GhABF2 的表达上调，GhDPBF2 的表达下调，GA 信号基因（如 GhGID1C 和 GhGID1B）的表达上调。综上所述，褪黑素通过调节 ABA 和 GA 以及调节植物激素信号转导中激素相关基因的表达，增强了棉花种子的耐盐性。这有助于我们探索棉花抗性的调控机制，并为培育新品种提供基础。