Differentially expressed transcripts from cucumber (Cucumis sativus L.) root upon inoculation with Fusarium oxysporum f. sp. cucumerinum Owen

Fusarium wilt of cucumber is a serious vascular disease worldwide. The molecular interaction between cucumber (Cucumis sativus L.) and Fusarium oxysporum was investigated by construction and characterization of a suppression subtractive hybridization cDNA library, which was constructed from F. oxysporum-inoculated cucumber. To screen the differentially expressed genes, dot blotting was used with cDNA probes prepared from mRNAs of control and F. oxysporum-inoculated samples. The elevated expression levels and overall profiles over time of eight genes were conformed by semi-quantitative RT-PCR analysis. Acquired positive clones were subjected to sequence and homology search analysis. In total, 153 ESTs were acquired after screening. Among these 153 ESTs, 80 ESTs showed significant sequence similarity to known genes, 51 had unknown functions, 22 clones did not match any known sequences. Most of the ESTs with known functions were involved in defense response, metabolism and transcriptional regulation. So upon F. oxysporum inoculation, cucumber could express defense-related genes as well as enhance its metabolic activities. The most interesting finding was that several genes were related to ABA, suggesting ABA singling may play a positive role in defense mechanism in cucumber to F. oxysporum. Our study provides an overview of gene expression in F. oxysporum-inoculated cucumber, as well as useful information of the defense mechanism in plant to necrotrophic fungi pathogens.