Data on microsatellite markers in Colletotrichum gloeosporioides s.l., polymorphism levels and diversity range

High Genetic Diversity and Structure of Colletotrichum gloeosporioides s.l. in the Archipelago of Lesser Antilles

Colletotrichum gloeosporioides is a species complex of agricultural importance as it causes anthracnose disease on many crop species worldwide, and strong impact regionally on Water Yam (Dioscorea alata) in the Caribbean. In this study, we conducted a genetic analysis of the fungi complex in three islands of the Lesser Antilles-Guadeloupe (Basse Terre, Grande Terre and Marie Galante), Martinique and Barbados. We specifically sampled yam fields and assessed the genetic diversity of strains with four microsatellite markers. We found a very high genetic diversity of all strains on each island, and intermediate to strong levels of genetic structure between islands. Migration rates were quite diverse either within (local dispersal) or between islands (long-distance dispersal), suggesting important roles of vegetation and climate as local barriers, and winds as an important factor in long-distance migration. Three distinct genetic clusters highlighted different species entities, though there was also evidence of frequent intermediates between two clusters, suggesting recurrent recombination between putative species. Together, these results demonstrated asymmetries in gene flow both between islands and clusters, and suggested the need for new approaches to anthracnose disease risk control at a regional level.

Emergent Ascomycetes in Viticulture: An Interdisciplinary Overview

The reduction of pesticide usage is a current imperative and the implementation of sustainable viticulture is an urgent necessity. A potential solution, which is being increasingly adopted, is offered by the use of grapevine cultivars resistant to its main pathogenic threats. This, however, has contributed to changes in defense strategies resulting in the occurrence of secondary diseases, which were previously controlled. Concomitantly, the ongoing climate crisis is contributing to destabilizing the increasingly dynamic viticultural context. In this review, we explore the available knowledge on three Ascomycetes which are considered emergent and causal agents of powdery mildew, black rot and anthracnose. We also aim to provide a survey on methods for phenotyping disease symptoms in fields, greenhouse and lab conditions, and for disease control underlying the insurgence of pathogen resistance to fungicide. Thus, we discuss fungal genetic variability, highlighting the usage and development of molecular markers and barcoding, coupled with genome sequencing. Moreover, we extensively report on the current knowledge available on grapevine-ascomycete interactions, as well as the mechanisms developed by the host to counteract the attack. Indeed, to better understand these resistance mechanisms, it is relevant to identify pathogen effectors which are involved in the infection process and how grapevine resistance genes function and impact the downstream cascade. Dealing with such a wealth of information on both pathogens and the host, the horizon is now represented by multidisciplinary approaches, combining traditional and innovative methods of cultivation. This will support the translation from theory to practice, in an attempt to understand biology very deeply and manage the spread of these Ascomycetes.

A Molecular Assay Allows the Simultaneous Detection of 12 Fungi Causing Fruit Rot in Cranberry

Cranberry fruit rot (CFR) is arguably one of the most limiting factors of cranberry (Vaccinium macrocarpon) production throughout its growing areas. The disease is caused by a group of closely related fungi that require identification using long and cumbersome steps of isolation and microscopic observations of structural features. The objective of this study was to develop a molecular assay to simultaneously detect and discriminate 12 of the most important fungal species reported to be pathogenic on cranberry fruit to facilitate the diagnosis of CFR. As the first approach, internal transcribed spacers and large subunit regions of all fungi were sequenced and confirmed with sequences available in the NCBI database. These data were used to develop primers able to differentiate seven of the 12 species. The five remaining species, including three in the Phacidiaceae family and two in the Glomerellaceae family, were differentiated on the basis of a more discriminant marker, the translation elongation factor 1-α. Two PCR reactions were optimized to clearly delineate the 12 species. The multiplex test was first validated using pure fungal cultures; it was subsequently validated using fruit collected in cranberry beds in eastern Canada. In the latter case, the test was rigorous enough to clearly discriminate the fungal pathogens from contaminants. Within the tested samples, Physalospora vaccinii and Coleophoma empetri were most commonly found. This molecular test offers scientists, diagnosticians, and growers a powerful tool that can rapidly and precisely identify fungi causing CFR so they can implement appropriate control methods.