Genome-wide analysis of the L-type lectin-like receptor kinase (LecRLK) gene family in upland cotton and verification of the response of GhLecRLK90 to drought stress.

As an important cash crop, cotton is susceptible to drought stress, which leads to reduced yields. Receptor-like protein kinases are widely distributed in plants and play important roles in plant growth, development and stress response. In this study, 94 L-type LecRLK genes were identified in upland cotton, while 88, 49 and 55 LecRLK genes were identified in 3 additional cotton species, respectively. The LecRLKs were divided into four groups by phylogenetic and evolutionary analysis among Five species (Arabidopsis thaliana and four cotton species). In upland cotton, LecRLK was evenly distributed in the two subgenomes and was mostly localized to the cell membrane. The Ka/Ks values of 90% of the GhLecRLK genes were less than 1, indicating that GhLecRLK family genes were purified and selected. Analysis of promoter cis-acting elements revealed that the GhLecRLK gene contained multiple ABA and MYB response elements, and GO enrichment analysis revealed that the GhLecRLK gene was enriched in the biological process of hydrogen peroxide metabolism. RNA-seq analysis showed that some GhLecRLK genes were higher expression at 6-12 h after induction by drought stress. These highly expressed genes were verified by qRT-PCR in drought-tolerant material (Xinluzao 45) and drought-sensitive material (Xinluzao 26). GhLecRLK90 was significantly highly expressed at 6 h after drought stress induction, and the difference in expression between the two groups was significant. Viral-induced gene silencing (VIGS) of GhLecRLK90 was performed in the drought-tolerant material (Xinluzao 45), and the silenced plants exhibited severe wilting and had significantly lower peroxidase (SOD and POD) activity than the control plants. These results suggest that GhLecRLK90 potentially regulates peroxidase activity in response to drought stress.