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The discovery of new mechanisms of resistance and natural bioactive molecules could be two of the possible ways to reduce fungicide use in vineyard and assure an acceptable and sustainable protection against Plasmopara viticola , the grapevine downy mildew agent. Emission of volatile organic compounds (VOCs), such as terpenes, norisoprenoids, alcohols and aldehydes, is frequently induced in plants in response to attack by pathogens, such as P. viticola , that is known to cause a VOCs increment in cultivars harboring American resistance traits. In this study, the role of leaf VOCs in the resistance mechanism of two resistant cultivars (Mgaloblishvili, a pure Vitis vinifera cultivar, and Bianca, an interspecific hybrid) and the direct antimicrobial activity of four selected VOCs have been investigated. The leaf VOCs profiles, analyzed through solid-phase microextraction gas chromatography-mass spectrometry analysis, as well as the expression of six terpene synthases (TPSs), were determined upon pathogen inoculation. In both cultivars, the expression pattern of six TPSs increased soon after pathogen inoculation and an increment of nine VOCs has been detected. While in Mgaloblishvili VOCs were synthesized early after P. viticola inoculation, they constituted a late response to pathogen in Bianca. All the four terpenes (farnesene, nerolidol, ocimene and valencene), chosen according to the VOC profiles and gene expression analysis, caused a significant reduction (53–100%) in P. viticola sporulation. These results support the role of VOCs into defense mechanisms of both cultivars and suggest their potential role as a natural and eco-friendly solution to protect grapevine from P. viticola. • P. viticola infection induces the biosynthesis of VOCs in grapevine cultivars. • The terpene synthase genes are expressed following P. viticola colonization. • Farnesene, nerolidol, ocimene and valencene counteract P. viticola infection. [ABSTRACT FROM AUTHOR]

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum—ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run. [ABSTRACT FROM AUTHOR]

In all land plants, the outer surface of aerial parts is covered by the cuticle, a complex lipid layer that constitutes a barrier against damage caused by environmental factors and provides protection against nonstomatal water loss. We show in this study that both cuticle deposition and cuticle-dependent leaf permeability during the juvenile phase of plant development are controlled by the maize (Zea mays) transcription factor ZmFUSED LEAVES 1 (FDL1)/MYB94. Biochemical analysis showed altered cutin and wax biosynthesis and deposition in fdl1-1 mutant seedlings at the coleoptile stage. Among cutin compounds, ω-hydroxy fatty acids and polyhydroxy-fatty acids were specifically affected, while the reduction of epicuticular waxes was mainly observed in primary long chain alcohols and, to a minor extent, in long-chain wax esters. Transcriptome analysis allowed the identification of candidate genes involved in lipid metabolism and the assembly of a proposed pathway for cuticle biosynthesis in maize. Lack of ZmFDL1/MYB94 affects the expression of genes located in different modules of the pathway, and we highlighted the correspondence between gene transcriptional variations and biochemical defects. We observed a decrease in cuticle-dependent leaf permeability in maize seedlings exposed to drought as well as abscisic acid treatment, which implies coordinated changes in the transcript levels of ZmFDL1/MYB94 and associated genes. Overall, our results suggest that the response to water stress implies the activation of wax biosynthesis and the involvement of both ZmFDL1/MYB94 and abscisic acid regulatory pathways. [ABSTRACT FROM AUTHOR]