School of Life Science, Northwest Normal University, Lanzhou 730070, PR China.
Tibetan medical college, Qinghai University, Xining 810016, PR China.
Ecotoxicol Environ Saf. 2017 Jan;135:75-81. doi: 10.1016/j.ecoenv.2016.09.013. Epub 2016 Sep 29.
Ascorbic acid (AsA) and nitric oxide (NO) are well known and widespread antioxidants and gaseous molecules that regulate plant tolerance to several stresses. However, the relationship between them in plant response to stress, especially heavy stress, is largely unclear. This study demonstrated that both AsA and NO could enhance the tolerance of wheat seedlings to cadmium stress evidenced by root length change, which resulted from their roles in maintaining the balance in reactive oxygen species (ROS) and reducing the absorption of Cd. Furthermore, exogenous AsA led to a significant increase of NO content and endogenous AsA content in wheat roots, which could be weakened by the NO scavenger c-PTIO. In addition, c-PTIO also inhibits the NO-induced production of endogenous AsA. Although the AsA synthesis inhibitor lycorine significantly inhibited the inductive effect of exogenous AsA on endogenous AsA production, it has little effect on NO content. In addition, we found that the protective effects of NO and AsA on Cd stress were removed by c-PTIO and lycorine. These results indicated that NO accumulation could be necessary for exogenous AsA-induced cadmium tolerance and endogenous AsA production, and the exogenous AsA-induced endogenous AsA production was likely mediated by NO signaling pathways and together they induced the tolerance of wheat to cadmium stress.
抗坏血酸（AsA）和一氧化氮（NO）是众所周知的广泛存在的抗氧化剂和气体分子，它们可以调节植物对多种胁迫的耐受性。然而，它们在植物对胁迫的反应中的关系，尤其是在严重胁迫下的关系，在很大程度上还不清楚。本研究表明，AsA 和 NO 都可以通过改变根长来增强小麦幼苗对镉胁迫的耐受性，这是由于它们在维持活性氧（ROS）平衡和减少 Cd 吸收方面的作用。此外，外源 AsA 导致小麦根中 NO 含量和内源性 AsA 含量显著增加，而 NO 清除剂 c-PTIO 可以削弱这种增加。此外，c-PTIO 还抑制了 NO 诱导的内源性 AsA 的产生。虽然 AsA 合成抑制剂石蒜碱显著抑制了外源 AsA 对内源性 AsA 产生的诱导作用，但对 NO 含量影响不大。此外，我们发现，NO 和 AsA 对 Cd 胁迫的保护作用被 c-PTIO 和石蒜碱消除了。这些结果表明，NO 的积累对于外源 AsA 诱导的镉耐受性和内源性 AsA 的产生是必要的，而外源 AsA 诱导的内源性 AsA 的产生可能是由 NO 信号通路介导的，它们共同诱导了小麦对镉胁迫的耐受性。
