Identification and expression analysis of LRR-RLK genes reveal their roles in plant development and stress responses in Kiwifruit (Actinidia chinensis)

As an important economic crop, the growth and development of kiwifruit are sensitive to environmental stresses, which can lead to reduced yield and quality. Leucine-rich repeat receptor-like kinases (LRR-RLKs) constitute one of the largest groups of receptor-like kinases and play crucial roles in regulating plant growth and development, as well as responses to biotic and abiotic stresses. In this study, 307 LRR-RLK genes were identified in the kiwifruit genome and grouped into 13 subclades. A comprehensive analysis was conducted, encompassing physiochemical properties, evolutionary relationships, gene structure, conserved motifs, gene family expansion, functional annotation, tissue-specific expression, and responses to stresses. Members within each subclade displayed analogous conserved motifs, gene structures, and protein structures. During gene family expansion, 47.9% AcLRR-RLK genes originated from tandem or segmental duplication events and evolved under strong purifying selection. Most AcLRR-RLK genes were differentially expressed in kiwifruit tissues, with some members exhibited continuously increased expression during the fruit ripening process. Furthermore, a series of differentially expressed AcLRR-RLK genes were detected under biotic and abiotic stresses. This study establishes a foundational framework for understanding LRR-RLK members and provides valuable insights into the potential applications of molecular breeding in kiwifruit cultivation.