Hydrogen sulfide alleviates lead-induced photosynthetic and ultrastructural changes in oilseed rape

Hydrogen sulfide enhances salt tolerance through nitric oxide-mediated maintenance of ion homeostasis in barley seedling roots

Hydrogen sulfide (H2S) and nitric oxide (NO) are emerging as messenger molecules involved in the modulation of plant physiological processes. Here, we investigated a signalling network involving H2S and NO in salt tolerance pathway of barley. NaHS, a donor of H2S, at a low concentration of either 50 or 100 μM, had significant rescue effects on the 150 mM NaCl-induced inhibition of plant growth and modulated the K(+)/Na(+) balance by decreasing the net K(+) efflux and increasing the gene expression of an inward-rectifying potassium channel (HvAKT1) and a high-affinity K(+) uptake system (HvHAK4). H2S and NO maintained the lower Na(+) content in the cytoplast by increasing the amount of PM H(+)-ATPase, the transcriptional levels of PM H(+)-ATPase (HvHA1) and Na(+)/H(+) antiporter (HvSOS1). H2S and NO modulated Na(+) compartmentation into the vacuoles with up-regulation of the transcriptional levels of vacuolar Na(+)/H(+) antiporter (HvVNHX2) and H(+)-ATPase subunit β (HvVHA-β) and increased in the protein expression of vacuolar Na(+)/H(+) antiporter (NHE1). H2S mimicked the effect of sodium nitroprusside (SNP) by increasing NO production, whereas the function was quenched with the addition of NO scavenger. These results indicated that H2S increased salt tolerance by maintaining ion homeostasis, which were mediated by the NO signal.

Hydrogen sulfide alleviates the aluminum-induced changes in Brassica napus as revealed by physiochemical and ultrastructural study of plant

In the present study, ameliorating role of hydrogen sulfide (H2S) in oilseed rape (Brassica napus L.) was studied with or without application of H2S donor sodium hydrosulfide (NaHS) (0.3 mM) in hydroponic conditions under three levels (0, 0.1 and 0.3 mM) of aluminum (Al). Results showed that addition of H2S significantly improved the plant growth, photosynthetic gas exchange, and nutrients concentration in the leaves and roots of B. napus plants under Al stress. Exogenously applied H2S significantly lowered the Al concentration in different plant parts, and reduced the production of malondialdehyde and reactive oxygen species by improving antioxidant enzyme activities in the leaves and roots under Al stress. Moreover, the present study indicated that exogenously applied H2S improved the cell structure and displayed clean mesophyll and root tip cells. The chloroplast with well-developed thylakoid membranes could be observed in the micrographs. Under the combined application of H2S and Al, a number of modifications could be observed in root tip cell, such as mitochondria, endoplasmic reticulum, and golgi bodies. Thus, it can be concluded that exogenous application of H2S under Al stress improved the plant growth, photosynthetic parameters, elements concentration, and biochemical and ultrastructural changes in leaves and roots of B. napus.

Hydrogen sulfide alleviates cadmium-induced morpho-physiological and ultrastructural changes in Brassica napus

In the present study, role of hydrogen sulfide (H2S) in alleviating cadmium (Cd) induced stress in oilseed rape (Brassica napus L.) was studied under greenhouse conditions. Plants were grown hydroponically under three levels (0, 100, and 500µM) of Cd and three levels (0, 100 and 200µM) of H2S donor, sodium hydrosulfide (NaHS). Results showed that application of H2S significantly improved the plant growth, root morphology, chlorophyll contents, elements uptake and photosynthetic activity in B. napus plants under Cd stress. Moreover, addition of H2S reduced the Cd concentration in the leaves and roots of B. napus plants under Cd-toxicity. Exogenously applied H2S decreased the production of malondialdehyde and reactive oxygen species in the leaves and roots by improving the enzymatic antioxidant activities under Cd stress conditions. The microscopic examination indicated that application of exogenous H2S improved the cell structures and enabled a clean mesophyll cell having a well developed chloroplast with thylakoid membranes, and a number of mitochondria could be observed in the micrographs. A number of modifications could be found in root tip cell i.e. mature mitochondria, long endoplasmic reticulum and golgibodies under combined application of H2S and Cd. On the basis of these findings, it can be concluded that application of exogenous H2S has a protective role on plant growth, photosynthetic parameters, elements uptake, antioxidants enzyme activities and ultrastructural changes in B. napus under high Cd stress conditions.

Selenium inhibits root elongation by repressing the generation of endogenous hydrogen sulfide in Brassica rapa

Selenium (Se) has been becoming an emerging pollutant causing severe phytotoxicity, which the biochemical mechanism is rarely known. Although hydrogen sulfide (H2S) has been suggested as an important exogenous regulator modulating plant physiological adaptions in response to heavy metal stress, whether and how the endogenous H2S regulates Se-induce phytotoxicity remains unclear. In this work, a self-developed specific fluorescent probe (WSP-1) was applied to track endogenous H2S in situ in the roots of Brassica rapa under Se(IV) stress. Se(IV)-induced root growth stunt was closely correlated with the inhibition of endogenous H2S generation in root tips. Se(IV) stress dampened the expression of most LCD and DCD homologues in the roots of B. rapa. By using various specific fluorescent probes for bio-imaging root tips in situ, we found that the increase in endogenous H2S by the application of H2S donor NaHS could significantly alleviate Se(IV)-induced reactive oxygen species (ROS) over-accumulation, oxidative impairment, and cell death in root tips, which further resulted in the recovery of root growth under Se(IV) stress. However, dampening the endogenous H2S could block the alleviated effect of NaHS on Se(IV)-induced phytotoxicity. Finally, the increase in endogenous H2S resulted in the enhancement of glutathione (GSH) in Se(IV)-treated roots, which may share the similar molecular mechanism for the dominant role of H2S in removing ROS by activating GSH biosynthesis in mammals. Altogether, these data provide the first direct evidences confirming the pivotal role of endogenous H2S in modulating Se(IV)-induced phytotoxicity in roots.