Species of Colletotrichum are considered important plant pathogens, saprobes, and endophytes on a wide range of host plants. In Italy, several Colletotrichum species have been reported in glasshouse environments. In this study, we have explored the occurrence, diversity, and pathogenicity of Colletotrichum spp. associated with aromatic and ornamental plants belonging to the Lamiaceae family. Surveys were carried out during the 2011–2018 period in Liguria and Piedmont, Italy. A total of 19 Colletotrichum isolates were collected from symptomatic leaves and seeds of Ocimum basilicum (basil), Origanum vulgare (oregano) and different Salvia spp. A multi-locus phylogeny was established based on the basis of four genomic loci (ITS, GAPDH, ACT and TUB2). The aggressiveness of selected, representative isolates were tested. Colletotrichum isolates were identified as being members of three major species complexes: C. acutatum, C. destructivum, and C. gloeosporioides. Colletotrichum fioriniae, C. bryonicola, and C. fructicola were found in association with leaf lesions on Salvia leucantha, S. nemorosa, and S. greggii, respectively. Colletotrichum nigrum was isolated from twig lesions of S. greggii. Moreover, C. fioriniae and C. ocimi were found to be responsible for causing leaf anthracnose of oregano and basil, respectively. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in commercial glasshouses. The present study improves our understanding of Colletotrichum species associated with several hosts belonging to the Lamiaceae family, which are cultivated extensively throughout Italy for different purpose, and provides information that may be useful for an effective disease management program.
Species of Colletotrichum are considered among the most important plant pathogens, saprobes and endophytes on a wide range of ornamentals, fruits and vegetables. Several Colletotrichum species have been reported in nurseries and public or private gardens in northern Italy. In this study, the occurrence, diversity and pathogenicity of Colletotrichum spp. associated with several ornamental hosts was explored. Survey were carried out during the 2013–2019 period in Piedmont, Italy. A total of 22 Colletotrichum isolates were collected from symptomatic leaves and stems of two Campanula spp., Ceanothus thyrsiflorus, Coreopsis lanceolata, Cyclamen persicum, Hydrangea paniculata, Liquidambar styraciflua, Mahonia aquifolium and Rhyncospermum jasminoides. A multi-locus phylogeny was established based on the basis of three genomic loci (gapdh, act and tub2). The pathogenicity of selected, representative isolates was tested. Colletotrichum isolates were identified as members of four important species complexes: Acutatum, Gloeosporioides, Dematium and Destructivum. Colletotrichum fioriniae, C. nymphaeae and C. fuscum were found in association with leaf lesions of Mahonia aquifolium, Campanula rapunculoides and Coreopsis lanceolata, respectively. Colletotrichum lineola, C. grossum and C. cigarro were isolated from Campanula trachelium, Rhyncospermum jasminoides and Liquidambar styraciflua, respectively. Colletotrichum fructicola was found to be responsible of anthracnose of Ceanothus thyrsiflorus, Hydrangea paniculata, Cyclamen persicum and Liquidambar styraciflua. All the tested isolates were pathogenic and reproduced identical symptoms to those observed in private gardens and nurseries. The present study improves our understanding of Colletotrichum spp. associated with different ornamental hosts and provides useful information for an effective disease management programme.
Highbush blueberry is an increasingly important crop due to its economic value and demonstrated health benefits of blueberries. Leaf spots are considered as minor diseases of blueberry plants, but they adversely affect blueberry productivity, causing reduced photosynthetic activity, flower bud formation and berry production. Surveys of blueberry crops were conducted in Piedmont, Northern Italy, during 2019-2020. Fungi isolated from leaf spots of the blueberry cultivar ‘Blue Ribbon’ were identified as Colletotrichum helleniense through a robust multi-locus phylogeny. Eight genomic loci were considered: tub, gapdh, act, cal, his3, chs-1, ApMat and gs. Morphological characters of a representative strain were assessed. Pathogenicity was confirmed on four blueberry cultivars, although with different levels of aggressiveness to the cultivars. This study shows the importance of a polyphasic approach to investigate species of Colletotrichum, and the relevance of molecular tools for the species-level characterization within the ‘Kahawae’ clade. This is the first report of Colletotrichum helleniense causing leaf anthracnose on Vaccinium corymbosum.
Red raspberry (Rubus idaeus L.) represents a relevant crop which production has largely increased worldwide during the last decade. Cane blight is one of the most common diseases of red raspberry and it can produce considerable losses. During 2019–2021, surveys were conducted in red raspberry orchards in Cuneo province, Northern Italy, to investigate the etiology and pathogen diversity in association with cane blight. Eleven isolates were collected from symptomatic plants of the cultivars ‘Diamond Jubilee’ and ‘Grandeur’, and were identified through multi-locus phylogenies and morphological features. Three fungal species were identified: Paraconiothyrium fuckelii, Diaporthe eres and Neocosmospora parceramosa. Four different genomic regions were included in the molecular analyses: ITS, tef1, tub2 and rpb2. The species pathogenicity was confirmed and P. fuckelii was revealed as the most aggressive. This study provides an insight into raspberry cane blight in Italy and the genomic loci sequencing lay the basis to develop specific diagnostic protocols to monitor the presence of pathogens and to prevent disease spread, adopting effective integrated control strategies.
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