Diversity and pathogenicity of Lasiodiplodia species associated with banana crown rot in Northern and Northeastern Brazil

Crown rot is a major postharvest disease affecting bananas (Musa spp.), resulting in substantial economic losses by compromising fruit quality and limiting marketability. In 2023, symptoms of crown rot were observed on banana fruits sourced from ten states across the northern and northeastern regions of Brazil. Pathogen identification was carried out using morphological characteristics and multigene phylogenetic analysis based on the internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1-α), β-tubulin (tub2), and RNA polymerase II subunit (rpb2). A total of 116 fungal isolates recovered from diseased fruit exhibited morphological traits consistent with the genus Lasiodiplodia. Phylogenetic reconstruction based on concatenated multilocus data revealed that the new isolates belonged to the species Lasiodiplodia brasiliensis, Lasiodiplodia hormozganensis, Lasiodiplodia iraniensis, Lasiodiplodia laeliocattleyae, Lasiodiplodia pseudotheobromae, and Lasiodiplodia theobromae. Pathogenicity tests confirmed that all Lasiodiplodia species/isolates experimentally induced crown rot symptoms on banana fruits of cultivars 'Prata', 'Pacovan', and 'Terra'. Inoculated fungi were re-isolated from symptomatic tissues, which exhibited morphological characteristics identical to those of the original cultures, fulfilling Koch's postulates. This study represents the first large-scale and comprehensive survey on Lasiodiplodia species associated with banana crown rot in Brazil, revealing that a complex of at least six phylogenetically distinct Lasiodiplodia species are involved in the disease etiology.