Identification and expression analysis of LEA gene family members in cucumber genome

LEA (late embryogenesis abundant) proteins are firstly discovered in seeds and then identified in vegetative tissues of different plant species. They are mainly regulated under abiotic stress conditions. Although genome wide studies of different gene family members have been performed in cucumber, there is no such a study for LEA genes. We have identified 79 LEA genes in the cucumber genome. Based on phylogenetic analysis, CsLEA genes could be classified into seven groups in which structural motifs are relatively conserved. Tandem duplications play an important role in cucumber genome for LEA gene expansion. Orthologous and chromosomal relationships of CsLEA genes were observed based on comparative mapping analysis with other species. The in silico micro-RNA (miRNA) target analyses indicated that 37 CsLEA genes were targeted by different miRNAs, especially mir854 and mir414 are the most abundant identified ones. Public available RNA-seq data were analyzed for expression analysis of CsLEA genes in different tissues of cucumber. According to genome-wide expression analysis, nine CsLEA genes showed higher expression profiles in all tissues. The expression profiles of ten CsLEA genes in the root and leaf tissues of drought-stressed cucumber were examined using qRT-PCR. Among them, CsLEA-54 induced after stress application in leaf and root tissues and might provide adaptation to drought stress for cucumber. CsLEA-09, CsLEA-32 and CsLEA-57 genes responded to drought after 3 h later and might be considered as early response genes to water limitation. This research could help us to improve understanding of contribution of CsLEAs to drought tolerance in cucumber.