Non-anthocyanin polyphenols in healthy and Flavescence dorée infected Barbera and Nebbiolo leaves

Abstract

The first serious outbreak of Flavescence dorée (FD) in Piedmont (North-West Italy) dates back to 1998 in the Tortona area (Alessandria province). FD is a serious quarantine-worthy disease transmitted by the leafhopper Scaphoideus titanus Ball. Different Vitis vinifera L. biotypes react differently to the phytoplasma, in particular as to the accumulation of polyphenols in leaves. In this experimentation, we observed and described concentration and accumulation of the main classes of polyphenols in entire leaves and in leaf blades and veins of two varieties, Nebbiolo and Barbera, displaying different levels of susceptibility to FD. Their well-known different reactions could be related, at least partially, to leaf polyphenols, both as to concentrations and profiles. Nebbiolo displayed some specific traits: i) the higher percentage of incidence over totals of individual molecules known to be powerful antioxidants (caftaric acid over coutaric acid; quercetin glycosides over other flavonols); ii) the higher concentration of flavanols in veins with respect to Barbera and their wider profile (astilbin and a taxifolin-glycoside, this last accumulating exclusively in Nebbiolo).

Molecular memory of Flavescence dorée phytoplasma in recovering grapevines

“…Besides the increase in anthocyanins already attested in FDp-diseased 'Barbera' plants 7 , monomeric flavan 3-ols, such as catechines, were also more abundant in response to FDp than during recovery. Conversely, cumarins, cinnamates and hydroxycinnamiltartaric acids (HCA), such as caftaric and fertaric acids, and some flavonols, such as quercetin-3-glucuronide and kaempferol-3-glucuronide, were more concentrated in REC and H than in infected veins ( Supplementary Table S5), supporting recently published findings 41 . Total stilbenoids, particularly the piceid forms, were instead higher in FD than REC and H veins ( Supplementary Table S5).…”

“…Particularly, transcriptional changes underlying recovery are associated with a complete reprogramming of stress-mediated responses previously triggered by the infection and mainly affecting secondary and hormone metabolisms. Accordingly, hydroxycinnamates, the predominant group of non-flavonoid phenols in grape 43 , are specifically accumulated in REC samples (Supplementary Table S5 ), suggesting that the reduced amount of anthocyanins in the leaf veins of REC plants may divert carbon to the biosynthesis of phenylpropanoids 41 .…”

Polyphenolic diversity in Vitis sp. leaves

“…In some V. vinifera sativa varieties, we previously identified these molecules, particularly in veins (Kedrina-Okutan et al, 2018) where astilbin was the predominant compound. We also associated astilbin accumulation to a possible defense-mechanism in cv Nebbiolo (Ferrandino et al, 2019). In fact, in Nebbiolo leaves of plants affected by Flavescence dorée (FD), we found a significantly higher concentration of flavanonols compared to healthy vines, hypothesizing a possible capability to limit the pathogen development.…”

Flavescence Dorée Strain-Specific Impact on Phenolic Metabolism Dynamics in Grapevine (Vitis vinifera) throughout the Development of Phytoplasma Infection

“…Even though substantial data suggest phytoplasmas modulate phenolic metabolism, no study so far has identified putative effectors that could mediate this process. Although the impact of BNp infection on the phenolic profile of grapevine has been previously thoroughly investigated, − results for FDp are mostly lacking and only concentrated on a few groups of phenolic compounds. ,, Therefore, considering the data that suggest that FDp affects grapevine phenolic metabolism, our aim was to assess if there is a strain-specific impact. Considering that phenolic metabolism is an often-used biomarker of various stress conditions in plants, our aim was to evaluate it as a potential indicator of variable pathogenicity levels among FDp strains.…”

“…Although the impact of BNp infection on the phenolic profile of grapevine has been previously thoroughly investigated, 13−15 results for FDp are mostly lacking and only concentrated on a few groups of phenolic compounds. 9,11,16 Therefore, considering the data that suggest that FDp affects grapevine phenolic metabolism, our aim was to assess if there is a strain-specific impact.…”