Abstract
Hydrogen sulfide (H2S) is a cell signal molecule produced endogenously and involved in regulation of tolerance to biotic and abiotic stress in plants. In this work, we used molecular biology, physiology, and histochemical methods to investigate the effects of H2S on cadmium- (Cd-) induced cell death in Chinese cabbage roots. Cd stress stimulated a rapid increase of endogenous H2S in roots. Additionally, root length was closely related to the cell death rate. Pretreatment with sodium hydrosulfide (NaHS), a H2S donor, alleviated the growth inhibition caused by Cd in roots—this effect was more pronounced at 5 μM NaHS. Cd-induced cell death in roots was significantly reduced by 5 μM NaHS treatment. Under Cd stress, activities of the antioxidant enzymes were significantly enhanced in roots. NaHS + Cd treatment made their activities increase further compared with Cd exposure alone. Enhanced antioxidant enzyme activity led to a decline in reactive oxygen species accumulation and lipid peroxidation. In contrast, these effects were reversed by hydroxylamine, a H2S inhibitor. These results suggested that H2S alleviated the cell death caused by Cd via upregulation of antioxidant enzyme activities to remove excessive reactive oxygen species and reduce cell oxidative damage.
Highlights
Hydrogen sulfide (H2S) has become appreciated as an endogenous signaling molecule, after nitric oxide and carbon monoxide [1]
The results showed that H2S could decrease cell death rate to alleviate Cd-induced growth inhibition through regulating the reactive oxygen species (ROS) balance in Chinese cabbage roots
Of the positive effects of H2S on the plant growth inhibition caused by Cd
Summary
Hydrogen sulfide (H2S) has become appreciated as an endogenous signaling molecule, after nitric oxide and carbon monoxide [1]. In the 1980s, H2S release in plants was discovered [2]. Some genes encoding these enzymes, which are responsible for endogenous H2S generation, were recently cloned in higher plants. Two cysteine desulfhydrases with the ability to decompose cysteine to pyruvate, ammonia, and H2S have been identified: L-cysteine desulfhydrase (LCD) with L-cysteine as substrate and D-cysteine desulfhydrase (DCD) with D-cysteine as substrate [3, 4]. Alvarez et al reported a novel L-cysteine desulfhydrase, named DES1, which is an O-acetylserine(thiol)lyase homolog [5]. Some enzymes with similar function are being discovered, but detailed information remains limited
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