A two-component system family in Moso bamboo (Phyllostachys edulis) analysis reveals the role of PheRRB8 in salt stress

The two-component system (TCS) regulates plant growth and stress responses by affecting phytohormone signalling; however, its role in Moso bamboo (Phyllostachys edulis) is poorly understood. Here, we identified 87 Moso bamboo TCS genes (PheTCSs), including 24 that encode PheHKs (histidine kinases), 10 that encode PheHPts (histidine phosphotransfer proteins) and 53 that encode PheRRs (response regulators). The PheTCSs and their corresponding proteins were comprehensively analysed using bioinformatics: this covered their gene structure, conserved motifs, phylogenetic tree, cis-acting elements on promoters, collinearity analysis and transcriptome data. Within 24 h of subjecting Moso bamboo to salt and drought stress, the expression of PheRRB8 increased from 1.2-fold to 6.1-fold and from 8.1-fold to 31.9-fold, respectively. Subcellular localisation and transcriptional activity experiments demonstrated that PheRRB8 localised to the nucleus and cytoplasm and exhibited transactivation activity in yeast. Furthermore, in silico protein interaction predictions indicated that PheRRB8 may interact with most PheHPts. A weighted correlation network analysis centred on PheRRB8 revealed 500 co-expressed genes, which were mostly annotated as 'response to stimulus' in the Gene Ontology database and were enriched in the 'metabolism' pathway in the Kyoto Encyclopedia of Genes and Genomes database. Subsequently, PheRRB8 was overexpressed in Arabidopsis thaliana for functional studies. The phenotype and physiological indexes of PheRRB8-overexpressing transgenic A. thaliana plants under stress treatment showed that PheRRB8 weakened A. thaliana's tolerance to salt stress. Our results present the Moso bamboo TCS family more comprehensively to researchers and contribute to the understanding of Moso bamboo's responses to abiotic stresses.