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Wine is a kind of beverage with a variety of compounds beneficial to human health, which makes it popular all over the world and it contributes importantly to economics. The excessive oxidation of wine has always been a major problem in wine production and storage. Unlike traditional wines which are made from Eurasian grapes, wines made from muscadine grapes (Muscadinia rotundifolia Michx.) can maintain their sensory qualities under natural oxidation conditions for relatively long periods of time despite the insight mechanisms still being unclear. In this study, two muscadine wines, Carlos (CAL) and Noble (NOB), and two traditional wines, Chardonnay (CH) and Marselan (MAS), were chosen for comparison of their compositional alteration during oxidation, in order to analyze the principal components contributing to the antioxidant characteristics of muscadine wines. The DPPH, ORAC, color intensity, and total phenolic content changes during the natural oxidation process were analyzed. Six core significantly changed metabolites (SCMs, avicularin, beta-lactose, delphinidin-3-O-glucoside, ellagic acid, myricetin, and 4-methylcatechol [p < 0.05]) related to the oxidation process were determined. In addition, HPLC–MS was also used to identify pyrogallol which is a unique antioxidant compound in muscadine wine. The present work aims to reveal the crucial antioxidant compounds of muscadine wine and provide valuable information and a new platform for future research on wine oxidation. [ABSTRACT FROM AUTHOR]

Plasmopara viticola, the causal organism of grapevine downy mildew, secretes a vast array of effectors to manipulate host immunity. Previously, several cell death‐inducing PvRXLR effectors have been identified, but their functions and host targets are poorly understood. Here, we investigated the role of PvRXLR111, a cell death‐inducing RXLR effector, in manipulating plant immunity. When coexpressed with other PvRXLR effectors, PvRXLR111‐induced cell death was prevented. Transient expression of PvRXLR111 in Nicotiana benthamiana suppressed bacterial flagellin peptide flg22‐elicited immune responses and enhanced Phytophthora capsici infection. PvRXLR111 induction in Arabidopsis increased susceptibility to Hyaloperonospora arabidopsidis. PvRXLR111 expression in Pseudomonas syringae promoted bacterial colonization. By immunoprecipitation‐mass spectrometry analysis, yeast two‐hybrid, pull‐down, and bimolecular fluorescence complementation assays, it was shown that PvRXLR111 interacted with Vitis vinifera putative WRKY transcription factor 40 (VvWRKY40), which increased VvWRKY40 stability. Transient expression of VvWRKY40 in N. benthamiana inhibited flg22‐induced reactive oxygen species burst and enhanced P. capsici infection and silencing NbWRKY40 attenuated P. capsici colonization. These results suggest VvWRKY40 functions as a negative regulator in plant immunity and that PvRXLR111 suppresses host immunity by stabilizing VvWRKY40. [ABSTRACT FROM AUTHOR]

Based on previous cloning of VpRPW8‐e, we obtained a 1,126 bp VpRPW8‐e promoter sequence in this study. A large number of TATA‐boxes, CAAT‐boxes, and other cis‐acting elements were predicted including light‐responsive elements, hormone‐responsive elements, stress‐responsive elements, and growth‐ and development‐associated elements within the promoter sequence. To further investigate the function of this promoter, we examined its activity in response to biotic and abiotic stress. The VpRPW8‐e promoter was strongly activated by Plasmopara viticola infection, and activation also occurred when the orientation of the promoter was reversed, although to a lesser extent. Deletion analysis showed that the −1,126 to −475 bp region of VpRPW8‐e promoter had high activity. A promoter fragment 5′ deleted to −475 bp (P−475) was activated in response to heat and cold stress, and even more strongly in response to Phytophthora capsici and salicylic acid (SA). Furthermore, Transgenic Nicotiana benthamiana were generated, VpRPW8‐e driven by P−475 enhanced resistance to Ph. capsici in N. benthamiana. Based on these results, the −475 bp region was deduced to be an indispensable part of the VpRPW8‐e promoter. VpRPW8‐e promoter is involved in pathogen‐ and stress‐inducible expression. [ABSTRACT FROM AUTHOR]

The protein family with nucleotide binding sites and leucine-rich repeat (NBS-LRR) in plants stimulates immune responses caused by effectors and can mediate resistance to hemi-biotrophs and biotrophs. In our previous study, a Toll-interleukin-1(TIR)-NBS-LRR gene cloned from Vitis amurensis "Shuanghong", VaRGA1, was induced by Plasmopara viticola and could improve the resistance of tobacco to Phytophthora capsici. In this study, VaRGA1 in "Shuanghong" was also induced by salicylic acid (SA), but inhibited by jasmonic acid (JA). To investigate whether VaRGA1 confers broad-spectrum resistance to pathogens, we transferred this gene into Arabidopsis and then treated with Hyaloperonospora arabidopsidis (Hpa), Botrytis cinerea (B. cinerea), and Pseudomonas syringae pv. tomato DC3000 (PstDC3000). Results showed that VaRGA1 improved transgenic Arabidopsis thaliana resistance to the biotrophic Hpa and hemi-biotrophic PstDC3000, but decreased resistance to the necrotrophic B. cinerea. Additionally, qPCR assays showed that VaRGA1 plays an important role in disease resistance by activating SA and inhibiting JA signaling pathways. A 1104 bp promoter fragment of VaRGA1 was cloned and analyzed to further elucidate the mechanism of induction of the gene at the transcriptional level. These results preliminarily confirmed the disease resistance function and signal regulation pathway of VaRGA1, and contributed to the identification of R-genes with broad-spectrum resistance function. [ABSTRACT FROM AUTHOR]