Nitric oxide and hydrogen sulfide: an indispensable combination for plant functioning

Nitric oxide (NO) and hydrogen sulfide (HS) are gasotransmitters, which are involved in almost all plant physiological and stress-related processes. With its antioxidant regulatory properties, NO on its own ameliorates plant stress, while HS, a foul-smelling gas, has differential effects. Recent studies have shown that these signaling molecules are involved in intertwined pathway networks. This is due to the contrasting effects of NO and HS depending on cell type, subcellular compartment, and redox status, as well as the flux and dosage of NO and HS in different plant species and cellular contexts. Here, we provide a comprehensive review of the complex networks of these molecules, with particular emphasis on root development, stomatal movement, and plant cell death.V.P.S. is grateful to the Science and Engineering Research Board, New Delhi (EMR/2017/000518) for providing financial assistance to carry out this work. Research by F.J.C. is supported by a European Regional Development Fund cofinanced grant from the Ministry of Economy and Competitiveness (PID 2019-103924 GB-I00), the Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI 2020) (P18-FR-1359), and Junta de Andalucía (group BIO192), Spain. We apologize to all those authors whose work could not be cited due to space limitations