Studio dei meccanismi molecolari coinvolti nel determinismo sintomatologico di piante infette da virus e virus-satelliti

The aim of our work was to study the molecular mechanisms involved in symptoms appearance of plants inoculated either with a virus or with a virus-satellite complex. In the first case, we tried to set up a reliable method for an early identification of PVYNTN strains present in Italy and causing potato tuber necrosis. This, to prevent their spread in the field and to avoid severe yield losses, especially in seed potato production. We tried to localize the particular genomic region responsible for tuber necrosis. To this purpose, we carried out RT-PCR experiments using various primer combinations, covering PVY genomic regions larger than those previously used by other authors. As the previous researchers, though, we were not able to differentiate all NTN from others PVY strains. This probably because of the frequent virus variability, due to both genomic mutations and possible recombination events among different strains. In the second case, we studied the influence of Y-sat (CaRNA5 satellite) on symptoms of CMV (Cucumber mosaic virus) in Nicotiana benthamiana plants: strong yellowing appearance instead of simple mosaic. Wang et al (2004), inoculating the same infectious complex on tobacco plants transformed with a viral suppressor of plant silencing (HC-PRO), did not experience the occurrence of yellowing anymore and, therefore, hypotesized that changes in symptoms were due to plant post transcriptional gene silencing (PTGS) mechanism. In our case, inoculation of N. benthamiana plants transformed with another PTGS viral suppressor (p19), and other plants defective for RNA polymerase 6 (involved in systemic silencing), still resulted in yellowing appearance. This, to our opinion, suggests that in our system another possible mechanism is involved.

Glyphosate, Manganese, and Zinc Soybean Trial

Often there is yellowing of soybeans following glyphosate applications that has been attributed by some as manganese or zinc deficiency. There have been varied reports of impacts of this ‘yellow flash’ on soybean yields. The trial was conducted to investigate such claims.

Organic Practices for the Production of Butternut Squash

Growers of organic squash need effective ways to manage insect and disease problems. The squash bug (Anasa tristis) sucks sap, causing leaves to wilt and turn black. The squash vine borer (Melittia cucurbitae) can devastate winter squash plantings. Burrowing by larvae into the base of the stem causes yellowing and wilting. Organic insecticides are expensive, have limited efficacy, require many applications, and some kill beneficial as well as target insects.

The influence of simulated cataract on retinal vessel oximetry measurements

PURPOSE: To assess the impact of human crystalline lens opacification and yellowing, similar to that observed in patients with cataracts, on retinal vessel blood oxygen saturation measurements using custom manufactured soft contact lenses. METHODS: Ten healthy, non-smoking individuals were enrolled for this study. All subjects underwent digital blood pressure measurements, assessment of non-contact intra-ocular pressure, pupil dilation and retinal vessel oximetry using dual-wavelength photography (Oximetry Module, Imedos Systems). To simulate lens changes, three different contact lenses were inserted, one to simulate opacities followed by two more lenses to simulate different levels of lens yellowing (Cantor & Nissel). RESULTS: The measurements obtained showed an opposite change in arterial and venous oxygen saturation and optical density ratio across conditions, resulting in a statistically significant difference in arterial minus venous oxygen saturation value (p = 0.003). However, this difference was only significant for the 'opacity' condition but not for the 'yellowing' conditions. CONCLUSION: Lenticular changes such as cataracts can impact on spectrophotometric analysis in particular dual-wavelength retinal vessel oximetry. Hence, lenticular assessment and cataract grading should be considered when assessing elderly individuals and patient groups developing cataract earlier in life such as those suffering from diabetes mellitus.

Nitrogen vs argon: what is the most effective atmosphere for shelf-life extension of buckler sorrel leaves?

Buckler sorrel (Rumex induratus Boiss. & Reut.) is an underutilized leafy vegetable with peculiar sensory properties and potential as a gourmet food. In the food industry, different packaging methods have been used for shelf-life extension, but it is important to know how the quality of minimally processed vegetable is affected by these treatments. Recently, nitrogen and argon have been used for food packaging. Nitrogen is low soluble in water and other food constituents and does not support the growth of aerobic microbes. In turn, argon is biochemically active and appears to interfere with enzymatic oxygen receptor sites. In this study, modified atmospheres enriched with nitrogen and argon were evaluated for shelf-life extension of buckler sorrel leaves. Wild samples were gathered in Bragança, Portugal, considering local consumers’ sites and criteria. Healthy and undamaged leaves were selected, rinsed in tap water, and a portion was immediately analyzed (non-stored control). The remaining fresh material was packaged in polyethylene bags under nitrogen- and argon-enriched atmospheres and a conventional control atmosphere (air). All packaged samples were stored at 4 ºC for 12 days and then analyzed. The headspace gas composition was monitored during storage. Different quality attributes were evaluated, including visual (colour), nutritional (macronutrients, individual sugars and fatty acids) and bioactive (hydrophilic and lipophilic molecules and antioxidant properties) parameters. Different statistical tools were used; the one-way analysis of variance (ANO VA) was applied for analyse the differences among treatments and a linear discriminant analysis (LDA ) was used to evaluate the effects on the overall postharvest quality. The argon-enriched atmosphere better prevent the samples yellowing. The proximate composition did not change significantly during storage. Samples in control atmosphere revealed higher protein and ash contents and lower levels of lipids. The non-stored control samples presented the higher amounts of fructose, glucose and trehalose. The storage time increased the palmitic acid levels and decreased the content in α-linolenic and linoleic acids. The γ- e δ-tocopherols were higher after the 12 days of cold storage. Probably, the synthesis of these lipophilic compounds was a plant strategy to fight against the abiotic stress induced by storage. Higher levels of total phenolics and flavonoids and increased reducing power and β-carotene bleaching inhibition capacity were also found in the stored control samples. Once again, this result may be attributed to the intrinsic plant-protection mechanisms. Overall, the argon atmosphere was more suitable for quality preservation and shelf-life extension of buckler sorrel.