Submitted to: Journal of Experimental Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/12/2009
Publication Date: 4/4/2009
Citation: Ioannidi, E., Kalamaki, M., Engineer, C., Petaraki, I., Alexandrou, D., Giovannoni, J.J., Kanellis, A. 2009. Expression profiling of ascorbic acid-related genes during tomato fruit development and ripening and in response to stress conditions. Journal of Experimental Botany. 60:663-678. Interpretive Summary: Fruit is a significant part of the human diet, supplying fiber, minerals, vitamins, and other chemopreventive agents such as antioxidants. Tomato is a nutritious component of the Mediterranean diet containing antioxidants such as ascorbic acid (vitamin C), ß-carotene, lycopene, lutein and zeaxanthin. The Mediterranean diet, rich in plant-derived foods, has been associated with lower risk of certain cancers and cardiovascular disease. Understanding the role of vitamin C in plant and fruit physiology provides us with opportunities to engineer the amount present in commercial crop varieties and to minimize losses due to post-harvest manipulation. Understanding vitamin C biosynthesis and metabolism in fruit tissues is required in order to develop plant foods with elevated vitamin C content. We present the monitoring of gene expression of enzymes involved in vitamin C biosynthesis, oxidation and recycling during tomato fruit ripening, in response to wounding, ethylene, heat and cold treatment, hypoxia and post-anoxic injury as first steps toward understanding the regulation of this important biosynthetic pathway.
Technical Abstract: L-Ascorbate (the reduced form of Vitamin C) participates in diverse biological processes including pathogen defense mechanisms, the modulation of plant growth and morphology and also acts as an enzyme cofactor, and redox status indicator. One of its chief biological functions is as an antioxidant. L-Ascorbate intake has been implicated in the prevention/alleviation of varied human ailments and diseases including cancer. To study the regulation of accumulation of this important nutraceutical in vegetables, we have characterized the expression of 22 tomato (Solanum lycopersicon) genes involved in the biosynthesis, oxidation and recycling of L-Ascorbate during the development and ripening of fruit. Taken together with L-Ascorbate abundance data, our results show distinct changes in the expression profiles for these genes implicating them in nodal regulatory roles during the process of L-Ascorbate accumulation in tomato fruit. We have further studied the expression of these genes in the context of abiotic and post-harvest stress, including the effects of heat, cold, wounding, oxygen supply and ethylene. Important aspects of the hypoxic and post-anoxic response in tomato fruit are discussed.