Publications by authors named "Markus Rienth"

Background: Priming plants with natural products is extensively studied in the agricultural field to reduce the use of synthetic and copper-based pesticides. Previous studies have shown that Oregano essential oil vapour (OEOV) is an effective priming agent against downy mildew (DM) in grapevine (Vitis vinifera L. cv.

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Article Synopsis
  • Downy mildew (DM), caused by the fungus Plasmopara viticola, is a major problem in grape growing and leads to heavy fungicide use, prompting a search for natural alternatives.
  • This study explored how oregano essential oil vapor (OEOV) affects DM-infected grapevines by examining genetic changes that occur when OEOV is applied before and after infection.
  • Results showed that OEOV significantly reduced DM sporulation and involved new gene pathways related to plant immunity, offering insights into natural antifungal strategies that do not rely on traditional methods.
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Grapevine leafroll disease (GLD) is one of the most economically damaging virus diseases in grapevine, with grapevine leafroll-associated virus 1 (GLRaV-1) and grapevine leafroll-associated virus 3 (GLRaV-3) as the main contributors. This study complements a previously published transcriptomic analysis and compared the impact of two different forms of GLD to a symptomless control treatment: a mildly symptomatic form infected with GLRaV-1 and a severe form with exceptionally early leafroll symptoms (up to six weeks before veraison) infected with GLRaV-1 and GLRaV-3. Vine physiology and fruit composition in 17-year-old Pinot noir vines were measured and a gradient of vigor, yield, and berry quality (sugar content and berry weight) was observed between treatments.

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The grapevine is subject to high number of fungal and viral diseases, which are responsible for important economic losses in the global wine sector every year. These pathogens deteriorate grapevine berry quality either directly the modulation of fruit metabolic pathways and the production of endogenous compounds associated with bad taste and/or flavor, or indirectly their impact on vine physiology. The most common and devastating fungal diseases in viticulture are gray mold, downy mildew (DM), and powdery mildew (PM), caused, respectively by , , and .

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In grapevines, as in other plants, sucrose and its constituents glucose and fructose are fundamentally important and carry out a multitude of roles. The aims of this review are three-fold. First, to provide a summary of the metabolism and transport of sucrose in grapevines, together with new insights and interpretations.

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Temperature, water, solar radiation, and atmospheric CO concentration are the main abiotic factors that are changing in the course of global warming. These abiotic factors govern the synthesis and degradation of primary (sugars, amino acids, organic acids, etc.) and secondary (phenolic and volatile flavor compounds and their precursors) metabolites directly, via the regulation of their biosynthetic pathways, or indirectly, via their effects on vine physiology and phenology.

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Tartaric acid (TA) is an obscure end point to the catabolism of ascorbic acid (Asc). Here, it is proposed as a "specialized primary metabolite", originating from carbohydrate metabolism but with restricted distribution within the plant kingdom and lack of known function in primary metabolic pathways. Grapes fall into the list of high TA-accumulators, with biosynthesis occurring in both leaf and berry.

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Leafroll viruses are among the most devastating pathogens in viticulture and are responsible for major economic losses in the wine industry. However, the molecular interactions underlying the effects on fruit quality deterioration are not well understood. The few molecular studies conducted on berries from infected vines, associated quality decreases with the repression of key genes in sugar transport and anthocyanin biosynthesis.

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The reduction of synthetic fungicides in agriculture is necessary to guarantee a sustainable production that protects the environment and consumers' health. Downy mildew caused by the oomycete Plasmopara viticola is the major pathogen in viticulture worldwide and responsible for up to 60% of pesticide treatments. Alternatives to reduce fungicides are thus utterly needed to ensure sustainable vineyard-ecosystems, consumer health and public acceptance.

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Background: Fruit composition at harvest is strongly dependent on the temperature during the grapevine developmental cycle. This raises serious concerns regarding the sustainability of viticulture and the socio-economic repercussions of global warming for many regions where the most heat-tolerant varieties are already cultivated. Despite recent progress, the direct and indirect effects of temperature on fruit development are far from being understood.

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Background: The increasing temperature associated with climate change impacts grapevine phenology and development with critical effects on grape yield and composition. Plant breeding has the potential to deliver new cultivars with stable yield and quality under warmer climate conditions, but this requires the identification of stable genetic determinants. This study tested the potentialities of the microvine to boost genetics in grapevine.

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Background: Global climate change will noticeably affect plant vegetative and reproductive development. The recent increase in temperatures has already impacted yields and composition of berries in many grapevine-growing regions. Physiological processes underlying temperature response and tolerance of the grapevine fruit have not been extensively investigated.

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A rapid and sensitive method is presented for the determination of proline in grape berries. Following acidification with formic acid, proline is derivatized by heating at 100 °C for 15 min with 3% ninhydrin in dimethyl sulfoxide, and the absorbance, which is stable for at least 60 min, is read at 520 nm. The method was statistically validated in the concentration range from 2.

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Diurnal changes in gene expression occur in all living organisms and have been studied on model plants such as Arabidopsis thaliana. To our knowledge the impact of the nycthemeral cycle on the genetic program of fleshly fruit development has been hitherto overlooked. In order to circumvent environmental changes throughout fruit development, young and ripening berries were sampled simultaneously on continuously flowering microvines acclimated to controlled circadian light and temperature changes.

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