Flavonoid profiling and biosynthetic gene expression in flesh and peel of two tomato genotypes grown under UV-B-depleted conditions during ripening

The aim of this study was to evaluate the effect of shielding solar ultraviolet B radiation on the accumulation of some flavonoids and their precursors hydroxycinnamic acids in tomato (Solanum lycopersicum) using LC-ESI-MS/MS. In particular, flesh and peel of two tomato hybrids, DRW 5981 and Esperanza, were separately analysed. The hybrids have been chosen on account of their different response to the light, since it was previously reported that they show a different pigmentation and an opposite behaviour under UV-B in terms of carotenoids and ascorbic acid content at different ripening stages. To determine the effect of UV-B radiation during tomato ripening, we also measured the expression of some flavonoid biosynthetic genes by Real Time RT-PCR analysis. The results here presented allowed us to conclude that UV-B radiation deeply and differentially affect the content of the considered flavonoids and hydroxycinnamic acids as well as the expression of some of their biosynthetic genes in both flesh and peel during the ripening process. On the other hand, the collected data clearly showed that this influence varies between different genotypes. We conclude that the use of specific plastic covers able to eliminate UV-B radiation may be an environmental-friendly approach to modulate the expression of structural genes and, in turn, to enhance healthy antioxidant compounds in fruits of specific tomato cultivars

Oxylipins from both pathogen and host antagonize jasmonic acid-mediated defence via the 9-lipoxygenase pathway in Fusarium verticillioides infection of maize

Oxylipins are a newly emerging group of signals that serve defence roles or promote virulence. To identify specific host and fungal genes and oxylipins governing the interactions between maize and Fusarium verticillioides, maize wild-type and lipoxygenase3 (lox3) mutant were inoculated with either F. verticillioides wild-type or linoleate-diol-synthase 1-deleted mutant (DFvlds1D). The results howed that lox3 mutants were more resistant to F. verticillioides. The reduced colonization on lox3 was associated with reduced fumonisin production and with a stronger and earlier induction of ZmLOX4, mLOX5 and ZmLOX12. In addition to the reported defence function of ZmLOX12, we showed that lox4 and lox5 mutants were more susceptible to F. verticillioides and possessed decreased jasmonate levels during infection, suggesting that these genes are essential for jasmonic acid (JA)-mediated defence. Oxylipin profiling revealed a dramatic reduction in fungal linoleate diol synthase 1 (LDS1)-derived oxylipins, especially 8-HpODE (8-hydroperoxyoctadecenoic acid), in infected lox3 kernels, indicating the importance of this molecule in virulence. Collectively, we make the following conclusions: (1) LOX3 is a major susceptibility factor induced by fungal LDS1-derived oxylipins to suppress JA-stimulating 9-LOXs; (2) LOX3-mediated signalling promotes the biosynthesis of virulence-promoting oxylipins in the fungus; and (3) both fungal LDS1- and host LOX3-produced oxylipins are essential for the normal infection and colonization processes of maize seed by F. verticillioides

Dietary exposure to fumonisins and evaluation of nutrient intake in a group of adult celiac patients on a gluten-free diet

Scope: The main objectives of this study were to estimate dietary fumonisin exposure and nutrient intake in a group of patients diagnosed with celiac disease compared to non-celiac subjects. Methods and results: The fumonisin level in 118 frequently consumed corn-based products was determined and dietary habits were recorded using a 7-day weighed food record. Data were then compared to those obtained for a control group. The fumonisin intake in the celiac patients was significantly higher than in controls, with mean values (\ub1 SE) of 0.395 \ub1 0.049 and 0.029 \ub1 0.006 g/kg body weight per day, respectively. With regard to nutritional habits, celiac patients showed a preference for a high fat diet, coupled with a high intake of sweets and soft drinks and a low intake of vegetables, iron, calcium and folate. Conclusion: These findings may have serious health implications for the celiac population due to the widespread occurrence of fumonisins in most of the widely consumed gluten-free products, leading to continuous exposure to this particular mycotoxin. Moreover, the recorded nutritional quality of the celiac patient\u2019s diet raises concerns regarding its long-term adequacy and its potential impact on chronic conditions such as type 2 diabetes and cardiovascular diseases

A true scale study of the maize chain with focus on free and hidden fumonisins and related fungi

The aim of this work was to study the dynamic profile of mycotoxin producing fungi and free and hidden fumonisins into raw maize collected in 28 fields and derived products. The maize bulk was stored in a commercial silo and used for milling. The reliability of the sampling approach, applied in different points at maize harvest-drying, was preliminary tested in this study. Fusarium section Liseola included the prevalent fungi in maize kernels; sampling, in field at harvest and at the storehouse, gave comparable results, while a reduction in fungi colony forming units was noticed after drying, attributed to the thermal treatment. Similar amounts of free and hidden fumonisins were detected, irrespective of the sampling step; this confirmed the reliability of the sampling approach. During silo discharge, till to 10 month storage, a significant decrease resulted both in free and total fumonisins. A significant increase of the free-to-total fumonisins ratio was observed moving from stored kernels to commercial flour, suggesting that milling leads to a reduction of the masked fraction. This result, together with the increase of free fumonisins after maize drying should be considered in future studies

Effect of UV-B depletion on flavonoid content and flavonoid biosynthetic gene expression in flesh and peel of wild-type and hp-1 tomato fruits during ripening

Flavonoids are a class of plant polyphenols that comprises up to 5000 different molecules, many of which have shown to be useful for human health. In plants, generally, they are ascribed to have an important role in plant defense, especially to ultraviolet radiation. Tomato is an important crop which is worldwide cultivated and eaten. It is the source of some health-beneficial secondary metabolites. The most represented ones are carotenoids but tomato fruit has proven a modest source of flavonoids too, especially in peel. Little is known about the possibility of enhancing flavonoids in tomato fruits by modulating light quality instead of biotechnological approaches and, therefore, aim of this study was to evaluate the effect of ultraviolet B radiation depletion on the expression of some genes involved in flavonoid biosynthesis and on the accumulation of some flavonoids in two tomato genotypes. Wild type and mutant hp-1 tomato plants were grown until complete fruit ripening under two different light conditions: whole sunlight spectrum and sunlight spectrum deprived of the UV-B region (280-320 nm). Flesh and peel of fruit were harvested at three different ripening stages and samples analyzed to evaluate the influence of the genotype and UV-B depletion on the flavonoid content and the expression of some flavonoid structural and regulatory genes. Our analyses indicate that the hp-1 mutation enhances flavonoid gene expression and accumulation both in flesh and peel. However light quality differentially affects the content of the phenolics analysed and the expression of some of the biosynthetic genes in the two tissues during the ripening process

Response of wild-type and high pigment-1 tomato fruit to UV-B depletion : flavonoid profiling and gene expression

The tomato high pigment-1 (hp-1) mutant is characterized by exaggerated photoresponsiveness and increased fruit pigmentation and carries a mutation in the HP1/LeDDB1 gene, encoding the tomato homologue of the negative regulator of the light signal transduction DDB1a from Arabidopsis. Here, we investigated the molecular events underlying flavonoid accumulation in flesh and peel of wild-type and hp-1 fruits in presence or absence of UV-B light. In hp-1 peel, a 2-fold higher level of rutin and an earlier accumulation of flavonoids than in wild-type were observed, which correlated to the earlier activation of most flavonoid biosynthetic genes compared to wild-type. In hp-1 flesh, flavonoid content was up to 8.5-fold higher than in wild-type and correlated to the higher transcript level of flavonoid genes compared to wild-type. In both tissues, the expression of flavonoid genes was correlated with the anticipated and/or enhanced activation of the light signal transduction genes LeCOP1LIKE, LeCOP1 and LeHY5. In wild-type, flavonoid content was severely reduced by UV-B depletion mostly in peel, whereas in hp-1 it was significantly increased in flesh. The activation of flavonoid and light signal transduction genes was UV-B dependent mostly at the mature green stage, whereas LeDDB1 expression was not regulated by UV-B