Phytotoxins Produced by Fungi Associated with Grapevine Trunk Diseases

Abstract

Up to 60 species of fungi in the Botryosphaeriaceae family, genera Cadophora, Cryptovalsa, Cylindrocarpon, Diatrype, Diatrypella, Eutypa, Eutypella, Fomitiporella, Fomitiporia, Inocutis, Phaeoacremonium and Phaeomoniella have been isolated from decline-affected grapevines all around the World. The main grapevine trunk diseases of mature vines are Eutypa dieback, the esca complex and cankers caused by the Botryospheriaceae, while in young vines the main diseases are Petri and black foot diseases. To understand the mechanism of these decline-associated diseases and the symptoms associated with them, the toxins produced by the pathogens involved in these diseases were isolated and characterised chemically and biologically. So far the toxins of only a small number of these decline fungi have been studied. This paper presents an overview of the toxins produced by the most serious of these vine wood pathogens: Eutypa lata, Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and some taxa in the Botryosphaeriaceae family, and examines how these toxins produce decline symptoms. The chemical structure of these metabolites and in some cases their vivotoxin nature are also discussed.

Extracellular compounds produced by fungi associated with Botryosphaeria dieback induce differential defence gene expression patterns and necrosis in Vitis vinifera cv. Chardonnay cells

“…These fungi produce a variety of compounds in their hosts as well as in artificial media, and some of these molecules have been characterised (for review, see Andolfi et al 2011). The effects of fungal extracellular compounds on defence gene expression in V. vinifera can be evaluated under different conditions: in the field, in greenhouses or in vitro.…”

“…To understand the toxicity, we decided to evaluate whether mellein which is produced by these fungi and is described as both a characteristic toxin of Botryosphaeriaceae and a possible diagnostic marker for diseased grapevines (Andolfi et al 2011), was responsible for the reactions observed in calli. Mellein was first reported as a toxin produced by D. seriata.…”

“…Given that pathogens can be found in the wood but never in the leaves of infected plants, it was hypothesised that the observed leaf and berry symptoms are actually caused by extracellular compounds produced by fungi in the discoloured woody tissues of the trunk, which then translocate to the leaves via the transpiration stream (Mugnai et al 1999). Botryosphaeriaceae produces phytotoxic metabolites whose synergic activities could lead to the foliar symptoms observed on grapevines; however, the cause of these symptoms and the role of these metabolites in disease development remain unclear (Andolfi et al 2011). Since the 1990s, some of the Botryosphaeriaceae phytotoxic metabolites have been isolated and characterised both chemically and biologically (for review, see Andolfi et al 2011).…”

“…Botryosphaeriaceae produces phytotoxic metabolites whose synergic activities could lead to the foliar symptoms observed on grapevines; however, the cause of these symptoms and the role of these metabolites in disease development remain unclear (Andolfi et al 2011). Since the 1990s, some of the Botryosphaeriaceae phytotoxic metabolites have been isolated and characterised both chemically and biologically (for review, see Andolfi et al 2011). Some earlier research identified phytotoxic exopolysaccharides that are secreted by botryosphaeriaceous fungi (Martos et al 2008), and more recently, two studies identified additional toxic compounds: mellein, cis-and trans-4-hydroxymellein, 4,7-dihydroxymellein, isosclerone and tyrosol (Djoukeng et al 2009;Evidente et al 2010).…”

“…Whereas isosclerone and tyrosol are produced by botryosphaeriaceous fungi and fungi causing esca; the melleins and their derivatives appear to be produced only by botryosphaeriaceous fungi. Moreover, Andolfi et al (2011) proposed mellein as a good diagnostic marker of diseased plants.…”