Genome-wide characterisation, evolution and expression analysis of the leucine-rich repeat receptor-like kinase (LRR-RLK) gene family in cucumbers.

The leucine-rich repeat receptor-like kinases (LRR-RLKs) compose a large gene family in plant genomes and implement essential functions in diverse plant physiology progress, including defence against pathogens. However, a systematic analysis of LRR-RLKs has not been accomplished in the economically important cucumber. 189 LRR-RLK genes were identified in the cucumber genome and further divided into 22 subgroups based on the sequence similarities in this study. A total of 31 segmental duplication events and 15 tandem duplication events were present in the genome, indicating that the two duplications were the main driving forces for the expansion of the LRR-RLK family in the cucumber. The expression profile analysis revealed that most of the CsLRR-RLKs were upregulated during a downy mildew infection, and resistant cucumbers comprised more upregulated CsLRR-RLKs than the sensitive lines. Taken together, our results provided information on the LRR-RLK gene family in the cucumber and contributed valuable information for the further research of CsLRR-RLKs. [ABSTRACT FROM AUTHOR]