<i>Diaporthe</i> diversity and pathogenicity revealed from a broad survey of grapevine diseases in Europe

Species of <i>Diaporthe</i> are considered important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Several species are well-known on grapevines, either as agents of pre- or post-harvest infections, including Phomopsis cane and leaf spot, cane bleaching, swelling arm and trunk cankers. In this study we explore the occurrence, diversity and pathogenicity of <i>Diaporthe</i> spp. associated with <i>Vitis vinifera</i> in major grape production areas of Europe and Israel, focusing on nurseries and vineyards. Surveys were conducted in Croatia, Czech Republic, France, Hungary, Israel, Italy, Spain and the UK. A total of 175 <i>Diaporthe</i> strains were isolated from asymptomatic and symptomatic shoots, branches and trunks. A multi-locus phylogeny was established based on five genomic loci (ITS, <i>tef1</i>, <i>cal</i>, <i>his3</i> and <i>tub2</i>), and the morphological characters of the isolates were determined. Preliminary pathogenicity tests were performed on green grapevine shoots with representative isolates. The most commonly isolated species were <i>D. eres</i> and <i>D. ampelina</i>. Four new <i>Diaporthe</i> species described here as <i>D. bohemiae</i>, <i>D. celeris</i>, <i>D. hispaniae</i> and <i>D. hungariae</i> were found associated with affected vines. Pathogenicity tests revealed <i>D. baccae</i>, <i>D. celeris</i>, <i>D. hispaniae</i> and <i>D. hungariae</i> as pathogens of grapevines. No symptoms were caused by <i>D. bohemiae</i>. This study represents the first report of <i>D. ambigua</i> and <i>D. baccae</i> on grapevines in Europe. The present study improves our understanding of the species associated with several disease symptoms on <i>V. vinifera</i> plants, and provides useful information for effective disease management.