Genome-wide identification and expression analyses of the LRR-RLK gene family in Actinidia chinensis

n this study, we identified and manually corrected <i>LRR-RLK</i> genes in two haplotypes of HY, resulting in a nonredundant set of 394 <i>AcLRR-RLK</i> genes. Phylogenetic analysis revealed that these <i>AcLRR-RLK</i> genes are classified into 21 subfamilies distributed across 29 chromosomes. Gene structure analysis revealed high diversity in the LRR domains of <i>AcLRR-RLK</i> genes, while the kinase domains were relatively conserved. Analysis of cis-acting elements further suggested the involvement of <i>AcLRR-RLK</i> genes in critical biological processes such as the light response, hormone response, growth and development, and biotic and abiotic stresses in HY. Furthermore, transcriptomic analysis across different tissues revealed that the majority of AcLRR-RLK genes play a role in five tissues: root, stem, leaf, flower, and fruit. Additionally, transcriptomic analysis under Psa infection indicated that, HY activated its defense response, with an increasing number of <i>AcLRR-RLK</i> genes responding to pathogen invasion. Among these genes, 48 <i>AcLRR-RLK</i> genes were identified as core genes responsive to <i>Psa</i>, and genes from subgroup XII may play a critical role in the defense mechanism against pathogen invasion. Our study provides an in-depth investigation into the characteristics and functions of the <i>AcLRR-RLK</i> gene family in A. chinensis, laying a molecular foundation for further disease-resistant and high quality breeding efforts.