College of Life Sciences, Laboratory Center of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Center of Hydrogen Science, Shanghai Jiao Tong University, Shanghai, 200240, China.
College of Life Sciences, Laboratory Center of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Free Radic Biol Med. 2020 Dec;161:1-14. doi: 10.1016/j.freeradbiomed.2020.09.021. Epub 2020 Sep 25.
Although ample evidence showed that exogenous hydrogen gas (H) controls a diverse range of physiological functions in both animals and plants, the selective antioxidant mechanism, in some cases, is questioned. Importantly, most of the experiments on the function of H in plants were based on pharmacological approaches due to the synthesis pathway(s) in plants are still unclear. Here, we observed that the seedling growth inhibition of Arabidopsis caused by low doses of mannitol could progressively recover by recuperation, accompanied with the increased hydrogenase activity and H synthesis. To investigate the functions of endogenous H, a hydrogenase gene (CrHYD1) for H biosynthesis from Chlamydomonas reinhardtii was expressed in Arabidopsis. Transgenic plants could intensify higher H synthesis compared with wild type and Arabidopsis transformed with the empty vector, and exhibited enhanced osmotic tolerance in both germination and post-germination stages. In response to mannitol, transgenic plants enhanced -Cys desulfhydrase (DES)-dependent hydrogen sulfide (HS) synthesis in guard cells and thereafter stomatal closure. The application of des mutant further highlights HS acting as a downstream molecule of endogenous H control of stomatal closure. These results thus open a new window for increasing plant tolerance to osmotic stress.
尽管有大量证据表明外源氢气（H）可控制动物和植物的多种生理功能，但在某些情况下，其选择性抗氧化机制仍受到质疑。重要的是，由于植物中的合成途径尚不清楚，大多数关于 H 在植物中功能的实验都是基于药理学方法。在这里，我们观察到低剂量甘露醇引起的拟南芥幼苗生长抑制可以通过恢复逐渐恢复，同时伴随着氢化酶活性和 H 合成的增加。为了研究内源性 H 的功能，我们从衣藻中表达了一种用于 H 生物合成的氢化酶基因（CrHYD1）在拟南芥中。与野生型和转化为空载体的拟南芥相比，转基因植物能够增强 H 的合成，并且在发芽和发芽后阶段均表现出增强的耐渗胁迫能力。对甘露醇的响应，转基因植物增强了保卫细胞中依赖 -Cys 脱巯基酶（DES）的硫化氢（HS）合成，随后气孔关闭。des 突变体的应用进一步强调了 HS 作为内源性 H 控制气孔关闭的下游分子的作用。这些结果为提高植物对渗透胁迫的耐受性开辟了新的途径。
