Marina Cavaiuolo

Nitrates and Glucosinolates as Strong Determinants of the Nutritional Quality in Rocket Leafy Salads

Rocket is an important leafy vegetable crop and a good source of antioxidants and anticancer molecules such as glucosinolates and other sulfur compounds. Rocket is also a hyper-accumulator of nitrates which have been considered for long time the main factors that cause gastro-intestinal cancer. In this review, the content of these compounds in rocket tissues and their levels at harvest and during storage are discussed. Moreover, the effect of these compounds in preventing or inducing human diseases is also highlighted. This review provides an update to all the most recent studies carried out on rocket encouraging the consumption of this leafy vegetable to reduce the risk of contracting cancer and other cardiovascular diseases.

The Antioxidants Changes in Ornamental Flowers during Development and Senescence

The concentration of antioxidant compounds is constitutive and variable from species to species and is also variable considering the development of the plant tissue. In this review, we take into consideration the antioxidant changes and the physiological, biochemical and molecular factors that are able to modulate the accumulation of antioxidant compounds in ornamental flowers during the whole development process until the senescence. Many ornamental flowers are natural sources of very important bioactive compounds with benefit to the human health and their possible role as dietary components has been reported. The most part of antioxidants are flower pigments such as carotenoids and polyphenols, often present in higher concentration compared with the most common fruits and vegetables. The antioxidants content changes during development and during senescence many biochemical systems and molecular mechanisms are activated to counteract the increase of reactive oxygen species and free radicals. There is a tight correlation between antioxidants and senescence processes and this aspect is detailed and appropriately discussed.

Development and optimization of an ELISA based method to detect Listeria monocytogenes and Escherichia coli O157 in fresh vegetables

Food-borne pathogen contamination of fresh produce represents a crucial problem in terms of food safety and economic losses. To avoid outbreaks and release of contaminated products in the market, food producers must assure that safety and control measures are followed throughout the production chain. Since traditional methods are complex and time consuming, the use of rapid and reliable methods is needed for a reproducible detection of low pathogen levels prior to packaging. To respond to this need, an indirect ELISA assay was developed to detect the presence of Listeria monocytogenes and Escherichia coli O157. Bacteria isolation procedure, antibody working concentration and limit of detection were studied and optimized to verify the presence of the two bacteria on cucumber. Incubation times for antigen (overnight, 4 °C), antibodies (60 minutes, 25 °C) and for substrate reaction (30 min, 25 °C) were selected. Results show that the ELISA method was highly sensitive with a detection limit lower than 103 CFU g−1 and relatively fast because bacteria isolation was achieved from 1 to 7 hours.

The maize fused leaves1 (fdl1) gene controls organ separation in the embryo and seedling shoot and promotes coleoptile opening.

Highlight This study provides the first characterization of an R2R3 family MYB transcription factor involved in cuticle and epicuticular wax deposition, whose action is confined to maize embryogenesis and juvenile phase.

Identification of innovative potential quality markers in rocket and melon fresh-cut produce

Ready-to-eat fresh cut produce are exposed to pre- and postharvest abiotic stresses during the production chain. Our work aimed to identify stress responsive genes as new molecular markers of quality that can be widely applied to leaves and fruits and easily determined at any stage of the production chain. Stress responsive genes associated with quality losses were isolated in rocket and melon fresh-cut produce and their expression levels analyzed by quantitative real time PCR (qRT-PCR) at different time points after harvest at 20 °C and 4 °C. qRT-PCR results were supported by correlation analysis with physiological and biochemical determinations evaluated at the same conditions such as chlorophyll a fluorescence indices, total, reducing sugars, sucrose, ethylene, ascorbic acid, lipid peroxidation and reactive oxygen species. In both species the putative molecular markers increased their expression soon after harvest suggesting a possible use as novel and objective quality markers of fresh-cut produces.

Gene expression analysis of rocket salad under pre-harvest and postharvest stresses : a transcriptomic resource for Diplotaxis tenuifolia

Diplotaxis tenuifolia L. is of important economic value in the fresh-cut industry for its nutraceutical and sensorial properties. However, information on the molecular mechanisms conferring tolerance of harvested leaves to pre- and postharvest stresses during processing and shelf-life have never been investigated. Here, we provide the first transcriptomic resource of rocket by de novo RNA sequencing assembly, functional annotation and stress-induced expression analysis of 33874 transcripts. Transcriptomic changes in leaves subjected to commercially-relevant pre-harvest (salinity, heat and nitrogen starvation) and postharvest stresses (cold, dehydration, dark, wounding) known to affect quality and shelf-life were analysed 24h after stress treatment, a timing relevant to subsequent processing of salad leaves. Transcription factors and genes involved in plant growth regulator signaling, autophagy, senescence and glucosinolate metabolism were the most affected by the stresses. Hundreds of genes with unknown function but uniquely expressed under stress were identified, providing candidates to investigate stress responses in rocket. Dehydration and wounding had the greatest effect on the transcriptome and different stresses elicited changes in the expression of genes related to overlapping groups of hormones. These data will allow development of approaches targeted at improving stress tolerance, quality and shelf-life of rocket with direct applications in the fresh-cut industries.