College of Life Sciences, Laboratory Center of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, China.
BMC Plant Biol. 2018 Sep 24;18(1):207. doi: 10.1186/s12870-018-1426-y.
Osmotic stress is a major abiotic stress limiting crop production by affecting plant growth and development. Although previous reports discovered that methane (CH) has a beneficial effect on osmotic stress, the corresponding downstream signal(s) is still elusive.
Polyethylene glycol (PEG) treatment progressively stimulated the production of CH in germinating mung bean seeds. Exogenous CH and sodium nitroprusside (SNP) not only triggered nitric oxide (NO) production in PEG-stressed plants, but also alleviated the inhibition of seed germination. Meanwhile, amylase activity was activated, thus accelerating the formation of reducing sugar and total soluble sugar. Above responses could be impaired by NO scavenger(s), suggesting that CH-induced stress tolerance was dependent on NO. Subsequent tests showed that CH could reestablish redox balance in a NO-dependent fashion. The addition of inhibitors of the nitrate reductase (NR) and NO synthase in mammalian (NOS), suggested that NR and NOS-like protein might be partially involved in CH-alleviated seed germination inhibition. In vitro and scavenger tests showed that NO-mediated S-nitrosylation might be associated with above CH responses.
Together, these results indicated an important role of endogenous NO in CH-enhanced plant tolerance against osmotic stress, and NO-regulated redox homeostasis and S-nitrosylation might be involved in above CH action.
渗透胁迫通过影响植物的生长和发育，从而限制作物的产量，是一种主要的非生物胁迫。尽管之前的研究发现甲烷（CH）对渗透胁迫有有益的影响，但相应的下游信号仍然难以捉摸。
聚乙二醇（PEG）处理逐渐刺激萌发绿豆种子中 CH 的产生。外源 CH 和硝普钠（SNP）不仅在 PEG 胁迫下的植物中引发了一氧化氮（NO）的产生，而且缓解了种子萌发的抑制。同时，淀粉酶活性被激活，从而加速还原糖和总可溶性糖的形成。上述反应可以被一氧化氮清除剂（scavenger）损害，这表明 CH 诱导的胁迫耐受性依赖于 NO。随后的测试表明，CH 可以以依赖于 NO 的方式重新建立氧化还原平衡。添加哺乳动物硝酸盐还原酶（NR）和一氧化氮合酶（NOS）抑制剂表明，NR 和 NOS 样蛋白可能部分参与了 CH 缓解种子萌发抑制的过程。体外和清除剂试验表明，NO 介导的 S-亚硝基化可能与上述 CH 反应有关。
综上所述，这些结果表明内源性 NO 在 CH 增强植物对渗透胁迫的耐受性中起着重要作用，NO 调节的氧化还原平衡和 S-亚硝基化可能参与了 CH 的作用。
