In Site Bioimaging of Hydrogen Sulfide Uncovers Its Pivotal Role in Regulating Nitric Oxide-Induced Lateral Root Formation

Hydrogen sulfide (H(2)S) is an important gasotransmitter in mammals. Despite physiological changes induced by exogenous H(2)S donor NaHS to plants, whether and how H(2)S works as a true cellular signal in plants need to be examined. A self-developed specific fluorescent probe (WSP-1) was applied to track endogenous H(2)S in tomato (Solanum lycopersicum) roots in site. Bioimaging combined with pharmacological and biochemical approaches were used to investigate the cross-talk among H(2)S, nitric oxide (NO), and Ca(2+) in regulating lateral root formation. Endogenous H(2)S accumulation was clearly associated with primordium initiation and lateral root emergence. NO donor SNP stimulated the generation of endogenous H(2)S and the expression of the gene coding for the enzyme responsible for endogenous H(2)S synthesis. Scavenging H(2)S or inhibiting H(2)S synthesis partially blocked SNP-induced lateral root formation and the expression of lateral root-related genes. The stimulatory effect of SNP on Ca(2+) accumulation and CaM1 (calmodulin 1) expression could be abolished by inhibiting H(2)S synthesis. Ca(2+) chelator or Ca(2+) channel blocker attenuated NaHS-induced lateral root formation. Our study confirmed the role of H(2)S as a cellular signal in plants being a mediator between NO and Ca(2+) in regulating lateral root formation.