Transcriptomic analyses reveal the effect of nitric oxide on the lateral root development and growth of mangrove plant Kandelia obovata

Background and aims Kandelia obovata, a dominant mangrove species in China, produces complex buttress roots and prop roots in intertidal wetlands where high quantities of nitric oxide (NO) are produced by reducing sediments. NO, a key signaling molecule, participates in an array of plant physiological and developmental processes. However, it is unclear whether NO functions in K. obovata root system establishment. Methods Here, we used a transcriptomic approach to investigate the potential role of NO in the regulation of K. obovata lateral root development and growth. Transcript profiles and bioinformatics analyses were used to characterize potential regulatory mechanisms. Results Application of exogenous sodium nitroprusside (SNP, an NO donor) enhanced K. obovata lateral root development and growth in a dose-dependent manner. Furthermore, the effects of SNP were abolished by the addition of cPTIO (NO scavenger). RNA-seq analysis identified 1,593 differentially expressed genes (DEGs), of which 646 and 947 were up- and down-regulated in roots treated with NO donor. Functional annotation analysis demonstrated that the starch and sucrose pathway was significantly induced in response to NO. A suite of DEGs involved in hormone signal transduction and cell wall metabolism was also differentially regulated by NO. Taken together, our results suggest that a complex interaction between energy metabolism, multiple hormone signaling pathways, and cell wall biosynthesis is required for the NO regulation on lateral root development and growth in mangrove plant K. obovata. Conclusion NO appears to contribute to the formation of the unique root system of mangrove plants.