ABSTRACT: Watermelon (Citrullus lanatus) is one of the most important vegetable crops in the world and accounts for 20% of the world’s total area devoted to vegetable production. Fusarium wilt of watermelon is one of the most destructive diseases in watermelon worldwide. Transcriptome profiling of watermelon during its incompatible interactions with Fusarium oxysporum f.sp. niveum (FON) was generated using an Agilent custom microarray which contains 15,000 probes representing approximately 8,200 watermelon genes. A total of 24, 275, 596, 598, and 592 genes that are differentially expressed genes between FON- and mock-inoculated watermelon roots at 0.5, 1, 3, 5 and 8 days post inoculation (dpi), respectively, were identified. Bioinformatics analysis of these differentially expressed genes revealed that during the incompatible interaction between watermelon and FON, the expression of a number of pathogenesis-related (PR) genes, transcription factors, signaling/regulatory genes, and cell wall modification genes, was significantly induced. A number of genes for transporter proteins such as aquaporins were down-regulated, indicating that transporter proteins might contribute to the development of wilt symptoms after FON infection. In the incompatible interaction, most genes involved in biosynthesis of jasmonic acid (JA) showed expressed stronger and more sustained than those in compatible interaction in FON-infected tissues. Similarly, genes associated with shikimate-phenylpropanoid-lignin biosynthesis were also induced in incompatible interaction, but expression of these genes were not changed or repressed in the compatible interaction. Fusarium oxysporum f.sp. niveum induced gene expression in watermelon root was measured at 0.5,1d, 3d, 5d and 8d after inoculation. Sample inoculated with water were used as the mock controls. Three independent experiments were performed.
