|Wechter, William - Pat|
Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2008
Publication Date: 6/5/2008
Citation: Wechter, W.P., Levi, A., Harris-Shultz, K.R., Davis, A.R., Fei, Z.J., Katzir, N., Giovannoni, J.J., Salman-Minkov, A., Hernandez, A., Thimmapuram, J., Tadmor, Y., Portnoy, V., Trebitsh, T. 2008. Gene expression in developing watermelon fruit. Biomed Central (BMC) Genomics. 9:275-282. Interpretive Summary: Watermelon is a major vegetable crop in the USA with a farm value of $300 million. The watermelon industry and consumers have great interest in improving watermelon fruit quality, as well as enhancing a specific carotenoid pigment called lycopene in the watermelon fruit. Lycopene, like many carotenoids found in a number of fruits and vegetables, are important dietary source of vitamin A in humans. Lycopenes, like those found in tomato and watermelon fruit, are being studied for their ability to reduced the risk of cancer, heart disease and eye degeneration. Developing more nutritious watermelon cultivars with high lycopene levels will help address consumer health needs. In addition, an understanding of the genetics involved in watermelon fruit development also greatly benefits growers by providing the seed industry the information needed to develop more disease resistant and vitamin rich cultivars. However, there is limited information about the genes that control watermelon fruit quality, particularly the genes controlling lycopene production in watermelon. Recently we developed a library of genes for watermelon fruit. In this study, we used an advanced technology, microarray analysis, to study the activity of more than 800 watermelon fruit genes during fruit development and ripening. We have identified 335 genes that appear to be involved in fruit development and nutritional quality, including several genes associated with lycopene production. The results of this study has provided the science community with a large pool of genes that are active in the watermelon fruit, and that can be used by industry and researchers to further improve watermelon and enhance its nutritional qualities.
Technical Abstract: A microarray and Real-Time PCR-based study was conducted in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] in order to elucidate the flow of events associated with fruit development and ripening in this species. RNA from three different maturation stages of watermelon fruit, as well as leaf, were collected from field grown plants during three consecutive years, and hybridized to custom, high-density, photolithography microarrays. Microarray analysis identified three hundred and thirty-five unique ESTs that are differentially regulated by at least two-fold in watermelon fruit during the early, ripening, or mature stage when compared to leaf. Of the 335 ESTs identified, 217 share significant homology with known gene products and 90 had no significant matches with any database accession. Of the modulated watermelon ESTs related to annotated genes, a significant number were found to be associated with or involved in the vascular system, ethylene biosynthesis, fruit softening, carotenoid and flavonoid biosynthesis, transcriptional regulation, and pathogen and stress response. Quantitative Real-Time PCR was used to further validate expression of 127 ESTs that were differentially expressed in developing and ripening fruit based on array analysis. This study highlights the importance of the vascular system and ethylene in fruit development and ripening and provides a foundation of information of genes that are involved in this process.