Functional analysis of cotton lectin receptor-like kinase gene GhLecRK1 in response to damage caused by Aphis gossypii Glover

【Objective】To clone cotton（Gossypium hirsutum）lectin receptor-like kinase（LecRK1）gene GhLecRK1 and analyze its function in the response to Aphis gossypii Glover damage，so as to provide theoretical reference for breeding new cotton varieties resistant to aphids.【Method】Based on the analysis of whole-transcriptome sequencing data of cotton leaves induced by A. gossypii，GhLecRK1 gene which responded to A. gossypii damage was cloned and its sequence was analyzed through bio-information method. Real-time fluorescence quantitative PCR was used to measure GhLecRK1 gene expression pattern under the induction of cotton aphids. Transient overexpression technique was utilized to study its function in cotton defense response to cotton aphids.【Result】The open reading frame（ORF）of GhLecRK1 gene was made up of 1233 bp and encoded 410 amino acid residues. The theoretical isoelectric point（pI）was 8.36，and the predicted molecular weight of GhLecRK1 protein was 45948 Da. GhLecRK1 protein was consisted of one α-mannose lectin binding domain，one S-glycoprotein domain（SLG），and one plasminogen/apple/nematode domain（PAN），therefore，it was a Gtype lectin receptor-like kinase. Homologous sequence analysis showed that GhLecRK1 had high sequence similarity （94.39%）with G-type LecRLKs sequences from other plants. Phylogenetic analysis of indicated that GhLecRK1 was most closely related to Gr012449778.1 from Gossypium raimondii. The expressions of GhLecRK1 gene in the cotyledon， root and stem in cotton plants at 24 h，48 h and 72 h after A. gossypii feeding were up-regulated to varying degrees，but the relative expressio of GhLecRK1 gene only significantly increased in the cotyledon at 24 h after A. gossypii feeding（P<0.05，the same below）. In addition，the results of selective and non-selective tests showed that the number of A. gossypii on transiently overexpressed GhLecRK1 gene cotton plants was less than those on WT plants and pMD plants respectively，and the amount of honeydew secreted by A. gossypii in overexpressed GhLecRK1 gene cotton plants was significantly reduced at 48 h after A. gossypii feeding.【Conclusion】GhLecRK1 gene responds to cotton defense response to A. gossypii. When GhLecRK1 gene is overexpressed in cotton plants，the resistance of cotton to A. gossypii is enhanced.