Organic acids are of fundamental importance in all plant species. They have been clearly described to have roles as important as photosynthate, energy production, carbon storage, biosynthesis of amino acids, stomatal conductance, and plant-microbe interactions (REF). In addition to these varied roles, organic acids are important for taste, being responsible for sourness and contributing to the flavour. Acidity is also one of the main ripening indices that determines the harvest date of fruits. But, in addition, in the fruit of tomato has shown that the levels of this acid are related to the maintenance of the quality of the fruit in post-harvest (Centeno et al., 2011; Lopez et al., 2015).
Understanding the mechanistic basic of ripening regulation and postharvest has been the focus of industry. In particular, tomato (Solanum lycopersicum) fruit has special importance since it is one of the most important horticultural crops worldwide (http://faostat3.fao.org/home/E). Also, tomato has emerged as the pre-eminent experimental model for studying fleshy fruit, including the developmental control of ripening and ethylene synthesis and perception (Carrari and Fernie, 2006; Hyang et al., 2009).
In this study, we investigated the photosynthesis and primary metabolome, of leaves and fruits jointly with ripening-related gene expression of fruit from transgenic tomato plants overexpressing a bacterial maleate isomerase gene to better understand the factors that influence the concentration of two important acids, fumarate and malate, in fruit and plant.
In the transgenic plants we observed dwarf phenotype, flowering delay, and alteration in postharvest life. Furthermore, metabolomics analysis allowed us to assess the changes of amino acids, sugars and organic acids during fruit ripening and leaf development of the transgenic plants indicating a pivotal role of malate and fumarate, as regulatory metabolites.