Characterization, evolution, and abiotic stress responses of leucine-rich repeat receptor-like protein kinases (LRR-RLK) in Liriodendron chinense.

BACKGROUND

Liriodendron chinense is susceptible to extinction due to the increasing severity of abiotic stresses resulting from global climate change, consequently impacting its growth, development, and geographic distribution. However, the L. chinense remains pivotal in both socio-economic and ecological realms. The LRR-RLK (leucine-rich repeat receptor-like protein kinase) genes, constituting a substantial cluster of receptor-like kinases in plants, are crucial for plant growth and stress regulation and are unexplored in the L. chinense.

RESULT

233 LchiLRR-RLK genes were discovered, unevenly distributed across 17 chromosomes and 24 contigs. Among these, 67 pairs of paralogous genes demonstrated gene linkages, facilitating the expansion of the LchiLRR-RLK gene family through tandem (35.82%) and segmental (64.18%) duplications. The synonymous and nonsynonymous ratios showed that the LchiLRR-RLK genes underwent a purifying or stabilizing selection during evolution. Investigations in the conserved domain and protein structures revealed that the LchiLRR-RLKs are highly conserved, carrying conserved protein kinase and leucine-rich repeat-like domians that promote clustering in different groups implicating gene evolutionary conservation. A deeper analysis of LchiLRR-RLK full protein sequences phylogeny showed 13 groups with a common ancestor protein. Interspecies gene collinearity showed more orthologous gene pairs between L. chinense and P. trichocarpa, suggesting various similar biological functions between the two plant species. Analysis of the functional roles of the LchiLRR-RLK genes using the qPCR demonstrated that they are involved in cold, heat, and salt stress regulation, especially, members of subgroups VIII, III, and Xa.

CONCLUSION

Conclusively, the LRR-RLK genes are conserved in L. chinense and function to regulate the temperature and salt stresses, and this research provides new insights into understanding LchiLRR-RLK genes and their regulatory effects in abiotic stresses.