The Role of Hydrogen Sulfide in Plant Roots during Development and in Response to Abiotic Stress

Abstract

Hydrogen sulfide (H₂S) is regarded as a "New Warrior" for managing plant stress. It also plays an important role in plant growth and development. The regulation of root system architecture (RSA) by H₂S has been widely recognized. Plants are dependent on the RSA to meet their water and nutritional requirements. They are also partially dependent on the RSA for adapting to environment change. Therefore, a good understanding of how H₂S affects the RSA could lead to improvements in both crop function and resistance to environmental change. In this review, we summarized the regulating effects of H₂S on the RSA in terms of primary root growth, lateral and adventitious root formation, root hair development, and the formation of nodules. We also discussed the genes involved in the regulation of the RSA by H₂S, and the relationships with other signal pathways. In addition, we discussed how H₂S regulates root growth in response to abiotic stress. This review could provide a comprehensive understanding of the role of H₂S in roots during development and under abiotic stress.

Keywords: auxin; heavy metal; hydrogen sulfide; nitric oxide; root growth; salt.

Figure 1

The proposed model of H₂S regulating plant root growth. Arrow and bar ends indicate activation and inhibitory effects, respectively. Green fonts represent genes or proteins, blue fonts represent signal molecules. H₂S: hydrogen sulfide; CH₄: methane; CA: cinnamaldehyde; BR: brassinosteroid; CO: carbon monoxide; NO: nitric oxide; DES1: L-cysteine desulfhydrase 1; HO1: haem oxygenase-1; RBOH1: respiratory burst oxidase 1; UGT74B1: UDP-glycosyltransferase 74B1; MPK6: mitogen-activated protein kinase 6; ABPs: actin-binding proteins; PINs: pin-formed family; SUT13: sugar transport protein 13; SWEET: bidirectional sugar transporter; INV: invertase; BSK: BR-signaling kinase; LBD16: LOB domain-containing protein 16.

Figure 2

The proposed model of H₂S alleviating plant root cell damage under abiotic stress. Arrow and bar ends indicate activation and inhibitory effects, respectively. The green, orange, and purple arrows refer to the response of H₂S in plant roots to heavy metals, hypoxia, and salt stress, respectively. H₂S: hydrogen sulfide; HM: heavy metal; ROS: reactive oxygen species; NO: nitric oxide; AsA-GSH cycle: ascorbate–glutathione cycle; ETH: ethylene; ADH: alcohol dehydrogenase; DES1: L-cysteine desulfhydrase 1; OASA1: o-acetylserine lyase isoform A1; SAT1: serine acetyltransferase 1; SAT5: serine acetyltransferase 5; PCS1/5: phytochelatin synthase 1/5; MT1A/1B/2B: metallothionein 1A/1B/2B; FRDL4: citrate efflux transporter; AACT1: citrate transporter.