Comprehensive Genome-Wide Characterization of L-Type Lectin Receptor-like Kinase (L-LecRLK) Genes in Wheat (Triticum aestivum L.) and Their Response to Abiotic Stress

L-type lectin receptor-like kinases (L-LecRLKs) play key roles in plant responses to environmental stresses and the regulation of growth and development. However, comprehensive studies of the L-LecRLK gene family in wheat (<i>Triticum aestivum</i> L.) are still limited. In this study, 248 L-LecRLK candidate genes were identified in wheat, which is the largest number reported in any species to date. Phylogenetic analysis grouped these genes into four clades (I-IV), with Group IV exhibiting significant monocot-specific expansion. Gene duplication analysis revealed that both whole-genome/segmental and tandem duplications contributed to family expansion, while Ka/Ks ratio analysis suggested that the genes have undergone strong purifying selection. The <i>TaL-LecRLK</i> genes displayed diverse exon-intron structures and conserved motif compositions. Promoter analysis revealed a <i>cis</i>-element associated with hormone signaling and abiotic stress responses. Transcriptome profiling showed that <i>TaL-LecRLKs</i> exhibit tissue- and stage-specific expression patterns. RNA-Seq data revealed that, under drought and heat stress conditions, <i>TaL-LecRLK35-3D</i> and <i>TaL-LecRLK67-6B</i> exhibited synergistic expression patterns, whereas <i>TaL-LecRLK67-6A</i> demonstrated antagonistic expression. A qRT-PCR further demonstrated that six <i>TaL-LecRLKs</i> may function through ABA-independent regulatory mechanisms. These findings provide valuable gene candidates for stress-resistant wheat breeding and shed light on the evolution and functional diversity of L-LecRLKs in plants.