Selenium Biofortification Impacts the Tomato Fruit Metabolome and Transcriptional Profile at Ripening.

In the present work, the effects of enriching tomatoes with selenium were studied in terms of physiological, metabolic, and molecular processes in the last stages of fruit development, particularly during ripening. A selenium concentration of 10 mg L-1 with sodium selenate and selenium nanoparticles was used in the spray treatments on the whole plants. No significant effects of selenium enrichment were detected in terms of ethylene production or color changes in the ripening fruit. However, selenium enrichment had an influence on both the primary and secondary metabolic processes and thus the biochemical composition of ripe tomatoes. Selenium decreased the amount of ß-carotene, increased the accumulation of naringenin and chlorogenic acid, and decreased the coumaric acid level. Selenium also affected the volatile organic compound profile, with changes in the level of specific apocarotenoid compounds, such as ß-ionone. These metabolomic changes may, to some extent, be due to the impact of selenium treatment on the transcription of genes involved in the metabolism of these compounds. RNA-seq analysis showed that the selenium application mostly impacted the expression of the genes involved in hormonal signaling, secondary metabolism, flavonoid biosynthesis, and glycosaminoglycan degradation.

Edible vegetables as a source of aldose reductase differential inhibitors.

The hyperactivity of aldose reductase (AR) on glucose in diabetic conditions or on glutathionyl-hydroxynonenal in oxidative stress conditions, the source of cell damage and inflammation, appear to be balanced by the detoxifying action exerted by the enzyme. This detoxification acts on cytotoxic hydrophobic aldehydes deriving from membrane peroxidative processes. This may contribute to the failure in drug development for humans to favorably intervene in diabetic complications and inflammation, despite the specificity and high efficiency of several available aldose reductase inhibitors. This paper presents additional features to a previously proposed approach, on inhibiting the enzyme through molecules able to preferentially inhibit the enzyme depending on the substrate the enzyme is working on. These differential inhibitors (ARDIs) should act on glucose reduction catalyzed by AR without little or no effect on the reduction of alkenals or alkanals. The reasons why AR may be an eligible enzyme for differential inhibition are considered. These mainly refer to the evidence that, although AR is an unspecific enzyme that recognizes different substrates such as aldoses and hydrophobic aldehydes, it nevertheless displays a certain degree of specificity among substrates of the same class. After screening on edible vegetables, indications of the presence of molecules potentially acting as ARDIs are reported.

Indoleacetic acid concentration and metabolism changes during bud development in tubers of two potato (Solanum tuberosum) cultivars.

Plant growth regulators are involved in the control of potato (Solanum tuberosum) tuber dormancy. Evidence concerning the role of IAA is controversial; we therefore investigated its role by analyzing two cultivars with varying lengths of dormancy. We examined the time course of free and conjugated IAA in tuber tissue isolates from the final stages of tuber growth to the end of dormancy, the distribution of free IAA in tuber tissues by in situ analysis, and the biosynthesis of the hormone by feeding experiments. The time course of free IAA showed marked differences between the examined cultivars, although the concentration of the auxin generally was the highest at the early stages of tuber dormancy. Immunodetection showed a similar pattern of IAA distribution in both genotypes: in dormant buds from freshly harvested tubers, the free hormone accumulated mostly in apical meristem, leaf and lateral bud primordia, and differentiating vascular tissues underlying the apical meristem, while at the end of the storage period only axillary bud primordia from growing buds displayed appreciable auxin levels. Feeding experiments indicated that changes in IAA biosynthesis rate were a major cause of auxin variation in buds. In both cultivars, dormancy apparently ceased when free IAA fell below a threshold value. Despite this, our data led us to conclude that IAA would not be directly responsible for inhibiting sprouting. Instead, auxin might shorten dormancy, in a cultivar-dependent manner, by enhancing early developmental processes in buds, ultimately leading to dormancy termination.