Diaporthe diversity and pathogenicity revealed from a broad survey of grapevine diseases in Europe

Abstract

Species of Diaporthe 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 Diaporthe spp. associated with Vitis vinifera 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 Diaporthe strains were isolated from asymptomatic and symptomatic shoots, branches and trunks. A multi-locus phylogeny was established based on five genomic loci (ITS, tef1, cal, his3 and tub2), 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 D. eres and D. ampelina. Four new Diaporthe species described here as D. bohemiae, D. celeris, D. hispaniae and D. hungariae were found associated with affected vines. Pathogenicity tests revealed D. baccae, D. celeris, D. hispaniae and D. hungariae as pathogens of grapevines. No symptoms were caused by D. bohemiae. This study represents the first report of D. ambigua and D. baccae on grapevines in Europe. The present study improves our understanding of the species associated with several disease symptoms on V. vinifera plants, and provides useful information for effective disease management.

Keywords: Vitis; canker; multi-locus sequence typing; pathogenicity.

Fig. 1

Consensus phylogram of 86 082 trees resulting from a Bayesian analysis of the combined ITS, tub2, his3, tef1 and cal sequence alignments of the D. eres complex. Bootstrap support values and Bayesian posterior probability values are indicated at the nodes. The asterisk symbol (*) represents full support (1/100). Substrate and country of origin are listed next to the strain numbers. Ex-type isolates are indicated in bold. The novel species are shown in red text. The tree was rooted to Diaporthe toxica (CBS 534.93).

Fig. 1

Consensus phylogram of 86 082 trees resulting from a Bayesian analysis of the combined ITS, tub2, his3, tef1 and cal sequence alignments of the D. eres complex. Bootstrap support values and Bayesian posterior probability values are indicated at the nodes. The asterisk symbol (*) represents full support (1/100). Substrate and country of origin are listed next to the strain numbers. Ex-type isolates are indicated in bold. The novel species are shown in red text. The tree was rooted to Diaporthe toxica (CBS 534.93).

Fig. 2

Consensus phylogram of 3 862 trees resulting from a Bayesian analysis of the combined ITS, tub2, his3, tef1 and cal sequence alignments of Diaporthe spp. Bootstrap support values and Bayesian posterior probability values are indicated at the nodes. The asterisk symbol (*) represents full support (1/100). Substrate and country of origin are listed next to the strain numbers. Ex-type isolates are indicated in bold. The novel species are shown in red text. The tree was rooted to Diaporthella corylina (CBS 121124).

Fig. 2

Consensus phylogram of 3 862 trees resulting from a Bayesian analysis of the combined ITS, tub2, his3, tef1 and cal sequence alignments of Diaporthe spp. Bootstrap support values and Bayesian posterior probability values are indicated at the nodes. The asterisk symbol (*) represents full support (1/100). Substrate and country of origin are listed next to the strain numbers. Ex-type isolates are indicated in bold. The novel species are shown in red text. The tree was rooted to Diaporthella corylina (CBS 121124).

Fig. 3

Diaporthe bohemiae (CBS 143347). a–c. Colonies on MEA, PDA and OA, respectively; d. conidiomata sporulating on PNA; e. conidiogenous cells; f. alpha conidia. — Scale bars = 10 μm.

Fig. 4

Diaporthe celeris (CBS 143349). a–c. Colonies on MEA, PDA and OA, respectively; d. conidiomata sporulating on OA; e. conidiophores; f. conidiogenous cells; g. alpha conidia; h. beta conidia. — Scale bars = 10 μm.

Fig. 5

Diaporthe hispaniae (CBS 143351). a–c. Colonies on MEA, PDA and OA, respectively; d. conidiomata sporulating on PDA; e. conidiogenous cells; f. alpha conidia; g. beta conidia. — Scale bars = 10 μm.

Fig. 6

Diaporthe hungariae (CBS 143353). a–c. Colonies on MEA, PDA and OA, respectively; d. conidiomata sporulating on PNA; e. conidiogenous cells; f. alpha conidia. — Scale bars = 10 μm.

Fig. 7

a–e. Natural and f–g. artificial symptoms on V. vinifera with associated Diaporthe species. a–c. Lesions of Phomopsis cane and leaf spot on shoot: a. initial symptoms (courtesy Alessandro Vitale); b. severe symptoms on green; c. dead shoot (courtesy José Luis Ramos Sáez de Ojer). — d–e. Cane bleaching (courtesy José Luis Ramos Sáez de Ojer). — f–g. External and internal discoloration of shoot inoculated with D. hispaniae (CPC 30323).