Stress responsive gene regulation in relation to hydrogen sulfide in plants under abiotic stress

Plants often face a variety of abiotic stresses, which affects them negatively and lead to yield loss. The antioxidant system efficiently removes excessive reactive oxygen species and maintains redox homeostasis in plants. With better understanding of these protective mechanisms, recently the concept of hydrogen sulfide (H₂S) and its role in cell signaling has become the center of attention. H₂S has been recognized as a third gasotransmitter and a potent regulator of growth and development processes such as germination, maturation, senescence and defense mechanism in plants. Because of its gaseous nature, H₂S can diffuse to different part of the cells and balance the antioxidant pools by supplying sulfur to cells. H₂S showed tolerance against a plethora of adverse environmental conditions like drought, salt, high temperature, cold, heavy metals and flood via changing in level of osmolytes, malonaldialdehyde, Na⁺/K⁺ uptake, activities of H₂S biosynthesis and antioxidative enzymes. It also promotes cross adaptation through persulfidation. H₂S along with calcium, methylglyoxal and nitric oxide, and their cross talk induces the expression of mitogen activated protein kinases as well as other genes in response to stress. Therefore, it is sensible to evaluate and explore the stress responsive genes involved in H₂S regulated homeostasis and stress tolerance. The current article is aimed to summarize the recent updates on H₂S-mediated gene regulation in special reference to abiotic stress tolerance mechanism, and cross adaptation in plants. Moreover, new insights into the H₂S-associated signal transduction pathway have also been explored.