Genetic structure and fungicide sensitivity of Botrytis cinerea populations isolated from grapevine in northern Italy

Abstract

Grey mould, caused by Botrytis cinerea, is a disease severely affecting grape production in northern Italy. However, little information is available on the variability of B. cinerea populations associated with grapevine. The mode of reproduction, sensitivity to fungicides, and for the first time in Italy, the genetic structure of B. cinerea populations isolated from grapevine in a northern Italian region are reported. Botrytis cinerea isolates (317) were completely genotyped for six microsatellite loci and characterized for the presence of the transposable elements Boty and Flipper, for the mating type and for resistance to cyprodinil, fludioxonil, boscalid and fenhexamid. All the isolates were found to belong to B. cinerea Group II, indicating the absence of B. pseudocinerea in the investigated areas. The populations possess a high genotypic diversity, different frequencies of transposable elements and a mixed mode of reproduction. At a regional level, B. cinerea populations belong to a large and interconnected pathogen population that includes the major grape-growing districts. The populations were generally sensitive to fungicides, with a low proportion (8%) of isolates resistant to cyprodinil, fludioxonil and boscalid. A small genetic distance was found between B. cinerea populations. However, the populations geographically isolated from the others by a mountain range showed a small but statistically significant genetic differentiation and a different pattern of fungicide resistance. The results show that northern Italian B. cinerea populations possess a high evolutionary potential and adaptive capacity.

Characterization of fungicide sensitivity profiles of Botrytis cinerea populations sampled in Lombardy (Northern Italy) and implications for resistance management

“…The EC 50 , which is the effective concentration of fungicide that reduces mycelial growth by 50% compared to the untreated control, was computed as a parameter of a log‐normal dose‐response model defined as follows: where y is the response variable associated to the inhibition level, c is the lower limit, d is the higher limit, Φ is the distribution function for Normal distribution, b is the model's slope, x is the fungicide's rate and e is the ED 50 . The sensitivity profile of each strain was determined according to the resistance factor (RF) …”

“…A previous study, principally aimed at characterizing the genetic variability of 317 B. cinerea strains isolated from 36 vineyards in Lombardy, showed that isolates resistant to cyprodinil, fludioxonil and boscalid were present at low frequency in the region . In this paper, 720 B. cinerea strains were isolated from the same vineyards with the objective of evaluating: (i) the frequency of resistant strains of B. cinerea isolated from vineyards treated with members of SDHI, AP, PP and KRI fungicides; (ii) the effect of the fungicide treatments carried out in vineyards on the selection of resistant strains; (iii) the genetic basis of resistance; and (iv) the fitness of resistant and sensitive strains.…”

Effect of year, sampling month and grape cultivar on noble rot incidence, mycelial growth rate and morphological type of Botrytis cinerea during noble rot development

“…Botrytis cinerea populations were widely studied in European wine regions suggesting that several factors can influence the population structure such as host, geographic origin, mode of reproduction, occurrence of mutations, the presence of transposon elements, and/or gene-flow (Campia et al 2016). Geographical diversity among the pathogen populations was associated with gray mold versus noble rot symptoms in various wine regions of France (Fournier et al 2013;Walker et al 2015).…”

A molecular epidemiology study reveals the presence of identical genotypes on grapevines and ground cover weeds and the existence of separate genetic groups in a Botrytis cinerea population

“…DNA was extracted from all the strains (63) and quantified (Campia et al ., 2017), and portions of six genes were amplified and sequenced. In detail, the genes analysed were: (a) ITS1‐ITS2, the internal transcribed spacer of the rDNA, widely used for phylogenetic analyses (Walker, 2016); (b) G3PDH , encoding glyceraldehyde‐3‐phosphate dehydrogenase, involved in basic cellular processes and with a moderate evolutionary rate (Staats et al ., 2005); (c, d) NEP1 and NEP2 , encoding necrosis‐ and ethylene‐inducing proteins that elicit cellular death in the host (Staats et al ., 2007); (e) sdh B , encoding the subunit B of succinate dehydrogenase that is the target protein of SDHI (succinate dehydrogenase inhibitor) fungicides (Leroux et al ., 2010); and (f) BC ‐hch , presumed to be involved in vegetative incompatibility (Fournier et al ., 2005).…”

“…cinerea possesses a prevalently heterothallic mating system, where sexual compatibility is controlled by a single mating type locus ( MAT1 ) with two idiomorphs: MAT1‐1 and MAT1‐2 (Faretra et al ., 1988; De Miccolis Angelini et al ., 2016). Fruiting bodies (apothecia) are rarely observed in nature, but cryptic sexual reproduction is likely to be occurring, as demonstrated by the low proportion of clones, low level of linkage disequilibrium, and analogous frequencies of strains harbouring the two mating types observed in field populations (Fournier and Giraud, 2008; Vercesi et al ., 2014; Shaw et al ., 2016; Campia et al ., 2017).…”