Bioinformatics And Functional Preliminary Analyses Of HD-zip Ⅳ Genes In Cucumber

Cucumber (Cucumis sativus L.) is one of the most important vegetable crops cultivatedworld-wide. The tuberculate trait is one of the important appearance qualities in cucumber,and the surface of the cucumber is controlled by fruit spine and tubercule genes. Themorphology and hereditary basis of the fruit spine are in accordance with trichomes, so thestudy on trichome genes is helpful to understand the molecular mechanism of cucumber spineformation. HD-Zip Ⅳ genes are related to trichome formation in dicots Arabidopsis andtomato. HD-Zip Ⅳ genes in cucumber were searched by BLASTP program. Detailedbioinformatics of cucumber HD-Zip Ⅳ genes, which include protein sequences, conservedregulatory motifs, phylogeny, gene structure,3’ UTR and alternative splicing (AS) wereanalyzed. The expression profiles of these genes in roots, stems, leaves, male flowers, fruitsand tendrils of the cucumber plants were represented using RT-PCR. Heterologous expressionin Arabidopsis and genetic transformation to cucumber were done to analyze the function ofcucumber HD-Zip Ⅳ genes. The main results were as follows:1. In this study,11cucumber HD-Zip Ⅳ genes were identified in the latest cucumbergenome, this family is smaller than other species that have been studied, it may due to theabsence of whole genome duplication events in cucumber genome and the absence of tandemand segmental duplications in cucumber HD-Zip Ⅳ gene family.2. Phylogenetic analysis showed that HD-Zip Ⅳ genes of seven plant species could beclassified into five subgroups and cucumber HD-Zip Ⅳ genes appear to be closely related tothe dicotyledons. Gene structures and conserved motifs composition of CsHDZⅣs showsimilarities with Arabidopsis, maize and poplar.3. Two conserved motifs of19nt and21nt were found in3’ UTR of6cucumberHD-Zip Ⅳ genes, suggested that a post-transcriptional regulatory mechanism may influencecucumber HD-Zip Ⅳ gene functions. In addition,6out of11cucumber HD-Zip Ⅳ geneswere found to undergo alternative splicing events.4. RT-PCR analysis showed that cucumber HD-Zip Ⅳ genes have different patterns oftissue expression, and the transcript signal was more obvious in reproductive tissues than invegetative tissues.5. The result of heterologous expression experiment showed that the expressions of CsHDZⅣ6and CsHDZⅣ8under the control of35S promoter can not complementArabidopsis mutant phenotype.6. Overexpression and silencing vectors of5cucumber HD-Zip Ⅳ genes wereconstructed in this study. Genetic transformation was also conducted in cucumber.In summary, we performed comprehensive bioinformatics, expression and functionpreliminary analyses of the HD-Zip Ⅳ gene family in cucumber, which provided clues touncover their biological roles in cucumber growth and development.