Abstract: L-type lectin receptor-like kinases (LecRKs) constitute a significant subfamily of plant receptor-like kinases, playing pivotal roles in plant development and immune responses. In this study, the CsLecRK gene family was systematically identified and analyzed in Camellia sinensis to explore their functions in growth, development and disease resistance. A total of 59 L-type CsLecRKs containing PF00069 and PF00139 domains were identified through HMMsearch analysis. Phylogenetic analysis shows these genes could be classified into 5 subgroups, revealing notable differences in exon-intron structures among the subgroups. Promoter region analysis shows enrichment of cis-acting elements associated with hormone responses and stress signaling pathways. Transcriptome data reveals that L-type CsLecRKs exhibited differential expressions in different tea plant tissues. qRT-PCR validation demonstrates that CsLecRK IV.1.2 and CsLecRK S.5 were significantly upregulated during the early stage of Colletotrichum camelliae infection and the later stages of Pestalotiopsis spp. infection. Notably, their expression levels were substantially higher in the resistant cultivar ‘Qianmei 419’ compared to the susceptible cultivar ‘Qianmei 818’, indicating their critical involvement in the immune response to pathogen infection. This study highlighted the critical mechanisms of L-type CsLecRKs in tea plant defenses against brown blight and anthracnose, elucidated the expression profiles of CsLecRK IV.1.2 and CsLecRK S.5 during pathogen infection, and demonstrated their potential to enhance disease resistance by activating the tea plant immune system. These findings provided valuable genetic resources and theoretical support for molecular breeding as well as green disease control strategies in tea plants.

Key words: tea plant, L-type lectin receptor kinases, tea anthracnose, tea brown blight, immune response