Hydrogen Sulfide Alleviates Manganese Stress in .

Hydrogen sulfide (HS) has been shown to participate in various stress responses in plants, including drought, salinity, extreme temperatures, osmotic stress, and heavy metal stress. Manganese (Mn), as a necessary nutrient for plant growth, plays an important role in photosynthesis, growth, development, and enzymatic activation of plants. However, excessive Mn in the soil can critically affect plant growth, particularly in acidic soil. In this study, the model plant was used to explore the mechanism of HS participation and alleviation of Mn stress. First, using wild-type with excessive Mn treatment, the following factors were increased: HS content, the main HS synthetase L-cysteine desulfhydrase enzyme (AtLCD) activity, and the expression level of the gene. Further, using the wild-type, deletion mutant () and overexpression lines ( and ) as materials, the phenotype of seedlings was observed by exogenous application of hydrogen sulfide donor sodium hydrosulfide (NaHS) and scavenger hypotaurine (HT) under excessive Mn treatment. The results showed that NaHS can significantly alleviate the stress caused by Mn, whereas HT aggravates this stress. The mutant is more sensitive to Mn stress than the wild type, and the overexpression lines are more resistant. Moreover, the mechanism of HS alleviating Mn stress was determined. The Mn content and the expression of the Mn transporter gene in the mutant were significantly higher than those of the wild-type and overexpression lines. The accumulation of reactive oxygen species was significantly reduced in NaHS-treated seedlings and overexpression lines, and the activities of various antioxidant enzymes (SOD, POD, CAT, APX) also significantly increased. In summary, HS is involved in the response of to Mn stress and may alleviate the inhibition of Mn stress on seedling growth by reducing Mn content, reducing reactive oxygen species content, and enhancing antioxidant enzyme activity. This study provides an important basis for further study of plant resistance to heavy metal stress.