Biscogniauxia rosacearum the charcoal canker agent as a pathogen associated with grapevine trunk diseases in Zagros region of Iran

Abstract

Grapevine trunk diseases (GTDs) are well-known and significant fungal diseases of Vitis vinifera with a worldwide distribution. During August to November 2016 in a survey to characterize fungi associated with grapevine trunk diseases in Kermanshah Province (west of Iran) vineyards, 286 fungal isolates were obtained. Based on morphology and DNA sequences data eight species were identified, of which Biscogniauxia rosacearum, Neoscytalidium hyalinum and Phaeoacremonium minimum were the most aggressive fungal pathogenic species characterized in this research. N. hyalinum was the most prevalent species. N. hyalinum and Ph. minimum have previously been reported from Vitis vinifera. Thus far, there are two records of Biscogniauxia mediterranea and Biscogniauxia capnodes on grapevine in the world with no data on pathology aspects. To our knowledge, it is the first time B. rosacearum is reported from grapevine across the globe. Pathogenicity test with three strains of B. rosacearum on 2-year-old potted grapevines confirmed the pathogenicity of B. rosacearum on grapevine. The proximity of vineyards to the oak trees in Zagros forests as one of the plant hosts of Biscogniauxia spp. further highlights the need for extensive studies on B. rosacearum as a new fungal pathogen.

Figure 1

One of the two most parsimonious trees obtained from analysis of ITS sequence data. MP bootstrap values based on 1000 pseudoreplicates are above the branches. The isolates and species characterized in this study are in boldface. Bar = 15 changes. Annulohypoxylon cohaerens YMJ 310 and Hypoxylon rubiginosum YMJ 24 were included as outgroups.

Figure 2

Disease symptoms caused by pathogenic fungi on grapevines in greenhouse conditions. (a) Curvularia spicifera. (b) Kalmusia variispora. (c) Neoscytalidium hyalinum. (d) Pheoacremonium minimum. (e) Truncatella angustata.

Figure 3

Biscogniauxia rosacearum colony, asexual morphology and disease symptoms on grapevine. (a) wedge-shape brown necrosis of wood in cross-sections of trunks and cordons from which B. rosacearum was isolated. (b) seven-day-old colony on MEA at 25 °C. (c,d) conidiophores and phialides. (e) conidia. (f–h) inoculated plant after six weeks, chlorosis and necrosis on leaves and wedge-shape brown necrosis of wood in cross-sections of shoots in greenhouse conditions. Bars = 7 μm.