Plant Pathology (2020) 69, 1125-1138

Dionicio Fuentes-Aragón, Vladimiro Guarnaccia, Angel Rebollar-Alviter, Sandra B. Juárez-Vázquez, Fortino Aguirre-Rayo and Hilda V. Silva-Rojas (2020)
Multilocus identification and thiophanate-methyl sensitivity of Colletotrichum gloeosporioides species complex associated with fruit with symptoms and symptomless leaves of mango
Plant Pathology 69 (6), 1125-1138
Abstract: Colletotrichum spp. are known causal agents of anthracnose in a broad host range, causing severe losses. Currently, the most effective way to reduce disease is by fungicide application, which could give rise to resistant populations. This study aimed to determine the Colletotrichum species present in conventional and organic mango orchards and to evaluate their pathogenicity and sensitivity to the benzimidazole fungicide thiophanate-methyl. Seventy-one isolates from fruit with symptoms and symptomless leaves were obtained. From these, 20 representative morphotypes were analysed based on glyceraldehyde-3-phosphate dehydrogenase partial gene sequencing. A subset of 10 isolates based on different species, isolation source, and fungicide sensitivity was used for morphological and multilocus phylogenetic analysis. Colletotrichum queenslandicum was only identified in conventional production systems, C . chrysophilum only in organic systems, and C . asianum and C . siamense in both. Pathogenicity tests showed all species were pathogenic, and only C . asianum caused symptoms via both unwounded and wounded inoculation methods. Overall, 25.3% of isolates (n = 18) that belong to C . siamense , isolated from a conventional orchard, grew on thiophanate-methyl amended media at 1,000 µg/ml, suggesting high resistance. Resistance was not correlated with any common point mutations at positions 198 and 200 of the β-tubulin 2 protein, as commonly found in other fungal pathogens resistant to benzimidazole. The 74.7% remaining isolates (n = 53) belonging to the other species were sensitive, reaching 100% inhibition at <10 µg/ml. Even with benzimidazole application, anthracnose symptoms persist due to the emergence of pathogenic Colletotrichum subpopulations that are resistant to thiophanate-methyl.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Vladimiro Guarnaccia, Angel Rebollar-Alviter

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution
pesticide resistance of pest

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Colletotrichum siamense	Mango (Mangifera indica)	Mexico
	Colletotrichum asianum	Mango (Mangifera indica)	Mexico
	Colletotrichum queenslandicum	Mango (Mangifera indica)	Mexico