Differential gene expression analysis in cucumber (Cucumis sativus L.) infected with Sphaerotheca fuliginea: a cDNA-AFLP-based study

Cucurbits powdery mildew, caused by Sphaerotheca fuliginea is an extremely damaging disease of cucumbers highly limiting its production throughout the world. However, little is investigated about factors and mechanisms involved in cucumber and S. fuliginea interaction. An amplified fragment length polymorphism-based analysis of complementary DNA (cDNA-AFLP) was used to comparatively profile gene expression patterns of two powdery mildew resistant and susceptible cucumber cultivars during interaction with S. fuliginea at 0, 24, 48, 96 hours post inoculation (hpi). Overall, 141 out of 1280 amplified transcription derived factors (TDF) showed differential regulation patterns with the majority (58%) of resistant cultivar TDFs being upregulated. By contrast, only 47% of susceptible cultivar TDFs were upregulated. The sequences of 55 differentially regulated TDFs were successfully obtained. According to BLAST homology search and bioinformatics analyses, sequences were mainly belonged to genes with functions involved in metabolism, regulatory, signaling and defence with 9, 8, 5 and 3 genes, respectively. The defence genes identified here can be suggested as the most possible candidate genes involved in the resistance of cucumber against S. fuliginea. The results of the present study give more insights into factors and mechanisms underlying the resistance of cucumber to powdery mildew caused by S. fuliginea and would be useful in cucumber breeding programs for releasing resistant cultivars against the pathogen.