Mango Microcosm: Unveiling the species diversity and pathogenic potential of fungi isolated from mango (Mangifera indica) in northern Thailand

Abstract

This study aimed to identify fungal pathogens responsible for diseases affecting mango orchards and fruits in the primary mango-growing regions of northern Thailand, and to evaluate their pathogenicity against mango. Mango leaves, branches, and fruits showing fruit and leaf anthracnose, leaf spots, fruit rot, stem-end rot, fruit decline, leaf and stem blight, and shoot dieback were collected and examined from Chiang Rai, Kalasin, Nan, and Sakon Nakhon provinces located in northern Thailand. The isolated fungi were identified based on morphological characteristics and multi-locus phylogenetic analysis based on the most reliable markers and loci combinations suggested for each genus. This study illustrates and describes nine pathogenic genera, including eight known genera and one new genus, Pseudopallidocercospora. Botryosphaeria fabicerciana, Botryosphaeria scharifii, Colletotrichum asianum, Colletotrichum gigasporum, Colletotrichum guajavae, Colletotrichum musae, Colletotrichum plurivorum, Colletotrichum siamense, Diaporthe rosae, Diaporthe siamensis, Diaporthe subellipicola, Neofusicoccum sinoeucalypti, Neopestalotiopsis chrysea, Neopestalotiopsis cubana, Neopestalotiopsis dendrobii, Neopestalotiopsis psidii, Neopestalotiopsis rhododendri, Neoscytalidium dimidiatum, Pestalotiopsis humicola and Pestalotiopsis menhaiensis were identified as known species. Five new species, including Neopestalotiopsis mangiferae, Neopestalotiopsis mangifericola, Neopestalotiopsis mangiferigena, Pseudopallidocercospora mangiferae, and Zasmidium mangiferae were fully illustrated and justified. Moreover, this study reports twelve globally new host-fungus occurrences and six new geographical records. Furthermore, pathogenicity assessment revealed that the majority of the isolates (91.6 %) were pathogenic against mango, while their virulence was significantly different. C. asianum was found to be the predominant pathogenic species with a frequency of 31.6 %. Haplotype networks generated using ITS sequence data for 220 C. asianum strains isolated from mango across 14 countries revealed eight haplotypes, indicating high genetic diversity (Hd = 0.5936) within the species. However, the analysis did not reveal a clear grouping of isolates based on their country of origin.