Spatial and temporal stolbur population structure in a cv. Chardonnay vineyard according to vmp1 gene characterization

Abstract

Bois noir is a grapevine disease caused by the stolbur phytoplasma. It is widespread in all European and Mediterranean viticultural areas, and it can induce severe damage to the quality and quantity of production. The recent disease recrudescence has encouraged studies on the use of molecular markers to assess the genetic diversity of stolbur strains. The aim of this study was to evaluate the presence of Bois noir symptoms and to monitor the spatial genetic structure of the stolbur population according to vmp1 genotypes, through 2011 and 2012 in a cv. Chardonnay vineyard. In both years, there were increased vines with symptoms from July to September. The analysis of dispersal indices showed that the spatial distribution was uniform in the vineyard. However, the two-dimensional contour maps show that Bois noir severity was higher in plants located on the borders than in the central parts of the vineyard. Stolbur population was composed of two prevalent vmp genotypes (V14, V12) across both years, along with other minor haplotypes (V3, V4, V9, V11, V15, V18, in 2011; V3, V18 in 2012). The data indicate that the vmp1 gene is an efficient marker to study the population structure of stolbur phytoplasma, to track the movement of the pathogen, and to identify the inoculum source, which will all serve in the planning of control strategies.

In-vineyard population structure of ‘Candidatus Phytoplasma solani’ using multilocus sequence typing analysis

“…Based on the information acquired during the survey carried out in September 2011, the symptomatic grapevines represented about 50% of all of the grapevines in the vineyard (Murolo et al, 2014), for which the average BN severity was 2.32. In the studied vineyard, 'Ca.…”

“…This collection was carried out in a commercial vineyard in central-eastern Italy (42°59 0 00 00 N, 13°36 0 00 00 E), with the infection previously assessed by molecular tools to belong to 'Ca. P. solani' (Murolo et al, 2014). Based on the information of BN severity of each infected vine recorded according to an empirical scale, as proposed in a previous study (Murolo et al, 2014), the disease severity that occurred in the vineyard and that was induced by different strains of 'Ca.…”

“…P. solani' (Murolo et al, 2014). Based on the information of BN severity of each infected vine recorded according to an empirical scale, as proposed in a previous study (Murolo et al, 2014), the disease severity that occurred in the vineyard and that was induced by different strains of 'Ca. Phytoplasma solani' was calculated according to the formula S = P (c  f)/n, where c is the severity class, f is the frequency of the class, and n is the number of symptomatic plants.…”

“…On the basis of the RFLP characterisation of the tuf gene (the present study) and the vmp1 gene (Murolo et al, 2014), representative samples amplified with specific primer pairs for the vmp1, stamp and secY genes were purified using Wizard SV gels and PCR Clean-Up kits (Promega Corporation, Madison, WI, USA), and quantified using a BioPhotometer (Eppendorf, Hamburg, Germany). These samples were sequenced using an ABI 3730XL DNA sequencer (Applied Biosystems, Carlsbad, CA, USA) at Beckman Coulter Genomics (Essex, UK), edited using the Chromas version 2.33 software, and assembled using the GAP4 Staden Package (http://www.staden.sourceforge.net), to obtain a consensus sequence.…”

“…P. solani'-infected grapevines (Murolo et al, 2014), 329 samples were used as the template for amplification with different primer pairs specific for 'Ca. P. solani'.…”