Identification of Ethylene-Responsive Genes in Ethrel-Treated Shoot Apices of Cucumber by Suppression Subtractive Hybridization

Abstract

Ethylene is one of the most important hormones for flowering of cucumber (Cucumis sativus L.). The molecular interaction between cucumber and ethylene was investigated by construction and characterization of a suppression subtractive hybridization cDNA library from stem apex of ethrel-treated cucumber. To screen differentially expressed genes, dot blotting was used with cDNA probes prepared from mRNAs isolated from control and ethrel-treated samples. Acquired positive clones were subjected to sequence and homology search analysis. In total, 103 expressed sequence tags (ESTs) were acquired after screening; among these, 73 showed significant sequence similarity to known genes, 26 had unknown functions, and four clones did not match any known sequences. Gene ontology (GO) analysis revealed that ESTs with known functions were involved in photosynthesis, metabolism, protein synthesis, cellular communication and transport, signal transduction, and transcriptional regulation. The expression levels and overall profiles in female and male buds of 11 ESTs were confirmed by reverse transcription polymerase chain reaction (RT–PCR) and three of them were detected by real-time quantitative PCR (qRT–PCR) in the whole plant. One of these was an F-box protein, EBF1 (EIN3 BINDING F-BOX1), which might play a positive role in female expression of cucumber.