Chapter 14 - Interplay between phytohormones and hydrogen sulfide regulates plant growth and development under normal and abiotic stresses

Abstract

Plant developmental physiology involves a combination of several environmental and intrinsic factors which along with genetic makeup influences its structure. Among endogenous signals, basic to this process are many growth regulators, termed as plant hormones or phytohormones. These are categorized into two broad groups: (1) traditional or classical hormones viz. auxins, gibberellins, cytokinins, abscisic acid, and ethylene and (2) newly discovered hormones, namely, jasmonates, brassinosteroids, and salicylic acid. At extremely low concentrations, these chemical messengers impact plant growth, tolerance to various stresses, and productivity whereas they may become detrimental at higher levels. Hydrogen sulfide (H2S) is an intrinsic gaseous transmitter or signaling molecule in plants that performs diverse roles in regulating plant growth and development under both normal and stressful conditions. Notwithstanding endogenous liberation of H2S, its exogenous application [extensively used H2S donor, sodium hydrosulfide (NaHS)] has revealed that H2S plays regulatory role in plant responses to several abiotic stresses. These responses require expression of certain genes and proteins that take part in metabolic pathways and signaling cascades stimulated via several phytohormones. Due to variations in H2S-mediated signaling grid, interplay of this gasotransmitter with plant hormones has been investigated in plant signaling. With this backdrop, this chapter summarizes cross talk of different phytohormones with H2S in modulating plant growth during normal conditions and in ameliorating negative effects of various abiotic stresses on plants. Furthermore, our current conception of signaling network involving phytohormones and H2S is also reviewed with an aim to highlight promising novel research directions.