Harpin Proteins Improve Bioactive Compounds Content in Crimson Seedless Table Grape

Pasquale Crupi,Gianvito Masi,Luigi Tarricone,Giambattista Debiase,Francesca Mangione

doi:10.2174/1874847301907010001

Abstract

Background:Frequently, in warm climates such as Mediterranean areas, a red-pink table grape ‘Crimson Seedless’ does not reach a good berry skin color; and an acceptable anthocyanin bioactive compounds content, responsible for the red color of berries. Harpin proteins are biotechnologically developed bio-activators that, if applied on plants during the growing period, trigger the expression of hundreds of genes among which those associated with the biosynthesis of bioactive compounds (such as anthocyanins).Aim:This research aimed at using harpin proteins to test their suitability in improving the grape skin color.Methods and Materials:Beta-harpin protein 1% p.a. (400 g/Ha) was applied to ‘Crimson Seedless’ vines three times at the beginning of veraison. Six samplings were carried out for both the treated and control grapes until commercial harvest. In the skin extracts, total and individual anthocyanins content was determined by UV-Vis and RP-HPLC-DAD analyses, respectively.Results:The collected results confirmed that the application of harpin proteins effectively stimulated the anthocyanin biosynthesis leading to make peonidin-3O-glucoside, cyanidin-3O-glucoside, and malvidin-3O-glucoside values from 2 to almost 10 folds higher in treated grapes than in control grapes (P< 0.05).Conclusion:Actually, harpin proteins improved the color of the berry skin, leading to a significantly higher concentration of anthocyanins in treated than in control grapes.

Highlights

Anthocyanins are the pigments which determine the color of grape varieties
The collected results confirmed that the application of harpin proteins effectively stimulated the anthocyanin biosynthesis leading to make peonidin-3O-glucoside, cyanidin-3O-glucoside, and malvidin-3O-glucoside values from 2 to almost 10 folds higher in treated grapes than in control grapes (P < 0.05)
Harpin Proteins (HrP), encoded by hpr genes from gram-negative plant pathogenic bacteria, are non-host-specific elicitors of the hypersensitive response [14] and can be considered as Plant Growth Regulators (PGRs), in the sense that, if applied on plants during the growing period, they trigger the expression of hundreds of genes related to the plant disease resistance, among which those involved in the biosynthesis of bioactive compounds (i.e. VvPAL, VvCHS, and VvUFGT) such as anthocyanins [15 - 17]

Summary

Introduction

Anthocyanins are the pigments which determine the color of grape varieties. Grapes with high levels of these compounds in their skin appear darker and more red-colored than grapes with low levels of anthocyanins, even though the relationship between pigments content and berry color is not linear [1, 2]. Harpin Proteins (HrP), encoded by hpr (hypersensitive response and pathogenicity) genes from gram-negative plant pathogenic bacteria, are non-host-specific elicitors of the hypersensitive response [14] and can be considered as PGR, in the sense that, if applied on plants during the growing period, they trigger the expression of hundreds of genes related to the plant disease resistance, among which those involved in the biosynthesis of bioactive compounds (i.e. VvPAL, VvCHS, and VvUFGT) such as anthocyanins [15 - 17]. The aim of this work was to apply foliar spraying on ‘Crimson Seedless’ grapes, a HrP commercial formulation (named PhCO2 – SIPCAM Italia S.p.A.), in order to improve the color and the anthocyanin content in grapes’ skin for overcoming the issue related to the coloration defect and giving higher nutraceutical quality to this variety. Harpin proteins are biotechnologically developed bio-activators that, if applied on plants during the growing period, trigger the expression of hundreds of genes among which those associated with the biosynthesis of bioactive compounds (such as anthocyanins)

Objectives

Results

Conclusion