Phenolic responses in 1-year-old canes of Vitis vinifera cv. Chardonnay induced by grapevine yellows (Bois noir)

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.