The molecular control of tomato fruit quality traits: the trade off between visual attributes, shelf life and nutritional value

Tomato (Solanum lycopersicum) is an established model to study fleshy fruit development and ripening and is an important crop in terms of its economic and nutritional value. Tomato fruit quality is a function of metabolite content which is prone to physiological changes related to fruit development and ripening. It has been described some ripening tomato mutants, delayed fruit deterioration (DFD), non-ripening (NOR) and ripening-inhibitor (RIN) which substantially extend “shelf life” in tomato for up to several months when defined in terms of softening, water loss and resistance to postharvest biotic infection. However, it is not known whether this extension in “shelf life” is in fact a desirable objective from the perspective of nutritional quality of the fruits. The aim of this work was to use a metabolomics approach join to genomic tools to characterize compositional changes (sugars, amino acids, organic acids and carotenoids) of non-softening tomato mutants reported (DFD, NOR and RIN) in comparison with the normally softening fruits (Ailsa Craig and M82) during ripening and postharvest shelf-life. Important results related with ripening gene expression and metabolic evolutions are shown

The effect of chilling and 1-MCP on quality attributes and physicochemical aspects of cell wall components of Passe-Crassane pears

Most winter pear cultivars, including Passe-Crassane, do not ripen at warm temperatures. Post-harvest exposure to chilling temperatures is re-quired for synchronize the onset of the climacteric increase in ethylene production and the ripening of individual fruit. During ripening pears softened, developing a melting texture after a period of shelf life. Softening and textural changes result principally from primary cell wall modifications. This study was initiated to evaluate the changes in cell wall fractions throughout the postharvest life of Passe-Crassane, comparing them with loss of firmness and with the production of ethylene dur-ing cold storage, ripening and failure to ripen. Pears (Pyrus communis L. \u2018Passa Crassana\u2019) were picked at commercial ripening stage; one group was kept at 20\ub0C, another was stored at 0\ub0 C and a third group was treated with 400 ppb of 1-MCP for 12 h before cold stor-age. Fruits were sampled after 30 days and cold-stored fruits after 135 days too. Flesh firmness was evaluated using a hand penetrometer. Internal ethylene concentration was determined with a gas chromatograph equipped with an alumina column. Isolation of cell wall material (alcohol insoluble solids, AIS) was obtained by extraction of fruit tissue in boiling ethanol. Samples of water-soluble and water-insoluble fractions of AIS were assayed spectrophotometrically for total uronic acid (UA) and by GLC for noncellulosic neutral sugar compositio

Trafficking Processes and Secretion Pathways Underlying the Formation of Plant Cuticles.

Cuticles are specialized cell wall structures that form at the surface of terrestrial plant organs. They are largely comprised lipidic compounds and are deposited in the apoplast, external to the polysaccharide-rich primary wall, creating a barrier to diffusion of water and solutes, as well as to environmental factors. The predominant cuticle component is cutin, a polyester that is assembled as a complex matrix, within and on the surface of which aliphatic and aromatic wax molecules accumulate, further modifying its properties. To reach the point of cuticle assembly the different acyl lipid-containing components are first exported from the cell across the plasma membrane and then traffic across the polysaccharide wall. The export of cutin precursors and waxes from the cell is known to involve plasma membrane-localized ATP-binding cassette (ABC) transporters; however, other secretion mechanisms may also contribute. Indeed, extracellular vesiculo-tubular structures have recently been reported in Arabidopsis thaliana (Arabidopsis) to be associated with the deposition of suberin, a polyester that is structurally closely related to cutin. Intriguingly, similar membranous structures have been observed in leaves and petals of Arabidopsis, although in lower numbers, but no close association with cutin formation has been identified. The possibility of multiple export mechanisms for cuticular components acting in parallel will be discussed, together with proposals for how cuticle precursors may traverse the polysaccharide cell wall before their assimilation into the cuticle macromolecular architecture