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

• H2S alleviated the toxic effects of Cd and improved the plant growth in B. napus.
• Application of H2S enhanced the photosynthetic parameters under Cd-stress.
• H2S regulated nutrients uptake in the leaves and roots of B. napus under Cd-stress.
• Exogenous H2S enhanced the antioxidant activities in B. napus under Cd-stress.
• H2S alleviated cell-structures in the leaves and roots of B. napus under Cd-stress.

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 500 µM) of Cd and three levels (0, 100 and 200 µM) 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.