The study was carried out on phytoplasma susceptible grapevine variety 'Chardonnay' (Vitis vinifera L.). The changes in total and individual phenolics, with a focus on hydroxycinnamic acids, flavanols and flavonol contents, were studied in phytoplasmasymptomatic and non-symptomatic berries of Bois noir (BN) infected and uninfected vines. Evident responses to BN infection at veraison have been monitored in a decreased accumulation of caftaric and coutaric acids, pcoumaroyl hexose, procyanidin B1, procyanidin trimer as well as of quercetin-3-O-glucoside, quercetin-3-O-glucuronide and quercetin-3-O-xyloside. At berry softening BN infection statistically increased the content of total phenolics, hydroxycinnamic acids and flavanols, but decreased the flavonol contents, especially at phytoplasmasymptomatic berry skins. Later, at harvest, the BN infection caused an additional significant decrease of coutaric acid and p-coumaroyl pentose contents, moreover of procyanidin B1 and procyanidin dimmers (1, 2, and 3), trimer, kaempferol-3-O-glucoside and of most identified quercetins, except of quercetin-3-O-xyloside. At harvest, non-symptomatic berries from infected plants showed similar dynamics in the total phenolic content compared to berry skins from uninfected plants, but in total flavanols and flavonols content similarity to those symptomatic was observed. The latter decreases grape quality and its antioxidant potential. The Bois noir disease showed specific, local and growth-phase-induced responses regarding the content of phenolics in berry skins, where in particular the differences between phytoplasmasymptomatic and non-symptomatic grapes have to be underlined. AbbreviationsBN bois noir HLT healthy (non infected) INF infected (bois noir) INFWS infected without symptom BBCH Biologische Bundesanstalt Bundessortenamt und Chemische Industrie Eur J Plant Pathol (2012) 133:965-974

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The influence of eggplant grafting on tomato rootstock was evaluated during the two growing seasons. Yield, quality traits, and individual phenolics in fruits were assessed. Three commercial varieties and one landrace were used as scions. Grafting significantly increased eggplant yield and decreased the presence of calyx prickles. The effect of grafting on the accumulation of major phenolic constituents in eggplant fruit was inconsistent: in the year with less solar radiation and lower mean daily air temperatures, grafting decreased phenolic content in commercial variety/rootstock fruit and increased the content in landrace/rootstock fruit. An opposite effect in the latter combination was observed in the year with improved conditions for eggplant cultivation. The browning potential of fruit pulp was highly dependent on variety/landrace and partly also on grafting combination. Differences in correlations between phenolic constituents and browning potential (positive for varieties and negative for landrace) could also be ascribed to the importance of other antioxidants for diminished eggplant pulp browning.

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Background and Aims Bois noir (BN) is developing into one of the most serious phytosanitary problems in global viticulture. The aim of this work was to study the phenolic substances in incompletely lignified shoots/canes from BN‐infected vines. Methods and Results The study was conducted on 25‐year‐old BN‐infected and BN‐free vines of Vitis vinifera cv. Chardonnay. Shoots and canes were sampled at three key phenological stages (BBCH 89 – berries ripe for harvest; BBCH 91 – after harvest, end of wood maturation; BBCH 97 – end of leaf‐fall), cut into three sections (base, middle and apex) and stored at −80°C until analysis. Phenolic substances were identified and quantified with a liquid chromatography‐mass spectrometry system with a reverse phase column. The BN infection affects the synthesis of ellagic acid derivatives, flavonoids and stilbenoids, especially in the earlier phenological stages of shoot/cane lignification. Modulation of the phenylpropanoid pathway occurred in canes from BN‐infected vines, leading to a significantly higher concentration of ferulate, 5‐hydroxyconiferyl aldehyde and eriodictyol‐5‐rhamnoside, quercetins, resveratrol trimers 1, 3, 4, vitisins, piceatannol and ε‐viniferins during shoot lignification (BBCH 89). Conclusions The study demonstrated that incomplete cane lignification caused by phytoplasma affected many phenolic substances, especially individual flavonoids and stilbenoids in earlier phenological stages of cane lignification. Moreover, the significantly higher concentration of identified hydroxycinnamic acid and monolignol derivatives and flavanone in canes from BN‐infected vines suggested an alteration of the monolignol pathway and may be responsible for the lack of cane maturation. Significance of the Study To our knowledge, this is the first paper that has reported a modulation of phenylpropanoid pathway in 1‐year‐old canes with incomplete lignification caused by phytoplasma.

Effects of spraying over apple trees (Malus domestica; 'Topaz') with methyl salicylic acid (MeSA) and SA during fruit maturation were investigated for quality parameters (weight, firmness, hue angle, red blush, yield) and phenolic profile of the peel and pulp (HPLC–mass spectrometry). These treatment effects were also investigated for activities of the phenylpropanoid pathway enzymes phenylalanine ammonia-lyase, chalcone synthase and isomerase (combined), and flavanone-3β-hydroxylase. The MeSA and SA treatments resulted in poor fruit peel coloration, with higher hue angles and 20% and 10% lower red blush, respectively. Anthocyanin levels were also significantly lower (56%) for MeSA treatment. MeSA stimulated activities of phenylalanine ammonia-lyase and chalcone synthase/isomerase, which resulted in higher levels of flavanols (to 34%), flavonols (to 33%), and hydroxycinnamic acids (to 29%), versus control. Therefore, while these salicylate treatments improve levels of some beneficial polyphenols, they also have negative effects on the external quality characteristics of the fruit.

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Phenolic compounds are involved in plant responses to various biotic and abiotic stress factors, with many studies suggesting their role in defense mechanisms against fungal pathogens. Soilborne vascular pathogen Verticillium nonalfalfae causes severe wilting and consequent dieback in a wide range of economically important crops, including hops (Humulus lupulus L.). In this study, we investigated the differential accumulation of phenolics in the susceptible “Celeia” and resistant “Wye Target” hop cultivars during the pathogenesis of Verticillium wilt. Quantitative polymerase chain reaction showed that colonization in the roots of both cultivars was intensive, but decreased continuously throughout the experiment in the resistant cultivar, while the relative fungal amount continuously increased in the stems of the susceptible cultivar. In response to colonization in the roots of the resistant cultivar, a significant increase in total flavanols was detected at three days postinoculation (dpi), suggesting a possible role in preventing fungus spread into the stems. The accumulation of phenolic compounds was less pronounced in the stems of the resistant cultivar since, compared to the latter, significant increases in flavonols at 3 and 15 dpi and hydroxycinnamic acids at 6 dpi were observed in the stems of the susceptible cultivar.