PDF(Pubmed)
Abstract：
Both melatonin and hydrogen sulfide (H2S) mitigate chromium (Cr) toxicity in plants, but the specific interaction between melatonin and H2S in Cr detoxification remains unclear. In this study, the interaction between melatonin and H2S in Cr detoxification was elucidated by measuring cell wall polysaccharide metabolism and antioxidant enzyme activity in maize. The findings revealed that exposure to Cr stress (100 μM K2Cr2O7) resulted in the upregulation of L-/D-cysteine desulfhydrase (LCD/DCD) gene expression, leading to a 77.8% and 27.3% increase in endogenous H2S levels in maize leaves and roots, respectively. Similarly, the endogenous melatonin system is activated in response to Cr stress. We found that melatonin had a significant impact on the relative expression of LCD/DCD, leading to a 103.3% and 116.7% increase in endogenous H2S levels in maize leaves and roots, respectively. In contrast, NaHS had minimal effects on the relative mRNA expression of serotonin-Nacetyltransferase (SNAT) and endogenous melatonin levels. The production of H2S induced by melatonin is accompanied by an increase in Cr tolerance, as evidenced by elevated gene expression, elevated cell wall polysaccharide content, increased pectin methylesterase activity, and improved antioxidant enzyme activity. The scavenging of H2S decreases the melatonin-induced Cr tolerance, while the inhibitor of melatonin synthesis, p-chlorophenylalanine (p-CPA), has minimal impact on H2S-induced Cr tolerance. In conclusion, our findings suggest that H2S serves as a downstream signaling molecule involved in melatonin-induced Cr tolerance in maize.
摘要：
褪黑激素和硫化氢（H2S）都可以减轻植物中铬（Cr）的毒性，但是褪黑素和H2S在Cr解毒中的具体相互作用尚不清楚。在这项研究中,通过测量玉米细胞壁多糖代谢和抗氧化酶活性，阐明了褪黑素与H2S在Cr解毒中的相互作用。研究结果表明，暴露于Cr胁迫（100μMK2Cr2O7）会导致L-/D-半胱氨酸脱硫酶（LCD/DCD）基因表达上调，导致玉米叶片和根中内源H2S水平增加77.8%和27.3%，分别。同样，内源性褪黑素系统响应Cr胁迫而被激活。我们发现褪黑素对LCD/DCD的相对表达有显著影响,导致玉米叶片和根中内源H2S水平增加103.3%和116.7%，分别。相比之下,NaHS对5-羟色胺-N乙酰转移酶（SNAT）的相对mRNA表达和内源性褪黑激素水平的影响最小。褪黑激素诱导的H2S的产生伴随着Cr耐受性的增加，基因表达升高证明了这一点，细胞壁多糖含量升高，增加果胶甲基酯酶活性，并提高了抗氧化酶的活性。H2S的清除降低了褪黑素诱导的Cr耐受性，而褪黑素合成的抑制剂，对氯苯丙氨酸(p-CPA),对H2S诱导的Cr耐受性影响最小。总之,我们的研究结果表明，H2S作为一个下游信号分子参与褪黑激素诱导的铬耐受玉米。
