Chromium (Cr) represents an important source of metallic stress in plants. Working with maize (Zea mays) seedlings, we characterize the suppressive effects of exogenously applied NaHS (a hydrogen sulfide; [H₂S] donor) on the toxic effects of Cr (VI). Heavy metal treatment reduced radicle and epicotyl lengths and fresh weights in seedlings at 6 and 9 days following germination. The negative Cr (200 μM) effect was countered by application with NaHS (500 μM) but this countering was reduced with the co-application of the H₂S generation inhibitor hydroxylamine (HA) or the H₂S scavenger hypotaurine (HT). The Cr-elicited H₂O₂ production was suppressed by NaHS and also by an inhibitor of the reactive oxygen species (ROS) generating NADPH oxidase (NOX). These effects were correlated with relative changes in carbomyl (-CO) and thiol (-SH) groups. Nitric oxide (NO) production increased by NaHS application with associated increase in S-nitrosoglutathione (GSNO) level, but low S-nitrosoglutathione reductase (GSNOR) activities indicating an elevated S-nitrosylation. Assessment of the role of the ascorbate-glutathione antioxidant cycle indicated that whilst ascorbate played at a best minor role, glutathione was more prominent. Methylglyoxal (MG) production was increased by Cr but reduced by NaHS through a mechanism which could be based on glutathione-S-transferase (GST) detoxification. Taken together data suggest that H₂S acts to counter Cr effect in maize by NOX suppression, mostly likely by the well-characterised S-nitrosylation mechanism, as well as a reduction of MG accumulation.

铬是植物中金属胁迫的重要来源。我们与玉米（Zea mays）幼苗一起工作，表征了外源施用NaHS（硫化氢； [H ₂ S]供体）对Cr（VI）毒性作用的抑制作用。重金属处理在发芽后第6天和第9天减少了幼苗的胚根和胚轴长度以及新鲜重量。通过使用NaHS（500μM）可以抵消负Cr（200μM）的影响，但同时使用H ₂ S生成抑制剂羟胺（HA）或H ₂ S清除剂次牛磺酸（HT）可以减少这种抵消作用。Cr引起的H ₂ O ₂NaHS以及产生NADPH氧化酶（NOX）的活性氧（ROS）抑制剂抑制了生产。这些影响与羰基（-CO）和硫醇（-SH）组的相对变化相关。一氧化氮（NO）的生产增加了硫氢化钠的应用与在相关联的增加小号-nitrosoglutathione（GSNO）水平，但低小号-nitrosoglutathione还原酶（GSNOR）指示升高的活动S-亚硝基化。对抗坏血酸-谷胱甘肽抗氧化剂循环作用的评估表明，尽管抗坏血酸发挥了最佳的次要作用，但谷胱甘肽却更为突出。铬可增加甲基乙二醛（MG）的产量，但NaHS可能通过一种基于谷胱甘肽-S-转移酶（GST）解毒。汇总的数据表明，H ₂ S通过抑制NOX来抵消玉米中的Cr效应，这很可能是由于特征明确的S-亚硝化机制以及MG积累的减少。