Genome-wide identification and functional analysis of the WRKY transcription factor family in Reynoutria japonica reveals its role in balancing growth and abiotic stress tolerance

Reynoutria japonica, known for its exceptional growth capacity and tolerance to multiple abiotic stresses, represents an ideal model for studying the trade-off between plant growth and stress adaptation. However, the molecular mechanisms underlying the balance between plant growth and stress resistance in R. japonica remain unclear. Increasing evidence indicates that WRKY proteins play a direct role in regulating the equilibrium between plant growth and resistance. In this study, we identified and conducted bioinformatics analysis about WRKY gene family from two haplotype chromosomes (HapA 89, HapE 82) in R. japonica. These 171 RjWRKY members distributed in three groups: group I (34), group II (115), and group III (22). RjWRKY members within the same group or subgroup typically exhibited similar conserved motifs and gene structures. Promoter sequences in the WRKY gene family contained a series of cis-acting elements related to plant growth and development, stress response, and hormone response. Based on transcriptome data, we screened 12 candidate RjWRKY genes that are associated with stem elongation and are simultaneously responsive to methyl jasmonate (MeJA, a stress-response ‘messenger’) and ultraviolet (UV) radiation. Further, we confirmed the relative expression levels of 12 RjWRKY genes during different stem-growth stages as well as under auxin (IAA) or auxin antagonist (PEO-IAA), salt, cadmium (Cd) and manganese(Mn) treatments by qRT-PCR. The 12 RjWRKY genes, responsive to both auxin signals and abiotic stress, may thus represent key regulators mediating the trade-off between plant growth and stress in this invasive plant species. In addition, overexpression of HuZ00251595.1 (a homology of AtWRKY11, designated as RjWRKY11) in A. thaliana significantly enhanced resistance to Cd. These results establish a solid foundation for further exploration into the functions of the RjWRKYs in the balance of growth and adaptation to various abiotic stresses in R. japonica.