DisplayTitle

Identification and Characterization of a Novel Etiological Agent of Mango Malformation Disease in Mexico, Fusarium mexicanum sp. nov.

First author: Colegio de Postgraduados, Campus Montecillo, Montecillo, Edo. Mex., C.P. 56230 México; second and third authors: Laboratorio de Patología Vegetal, IIAF, Universidad Michoacana de San Nicolás de Hidalgo, Km. 9.5 Carr. Morelia-Zinapécuaro, Michoacán 58880, México; fourth and eighth authors: Department of Plant Pathology and Weed Research, Agricultural Research Organization (ARO), The Volcani Center; P.O. Box 6, Bet Dagan, 50250, Israel; fifth author: Department of Plant Pathology, Tropical Research and Education Center, University of Florida, 18905 SW 280th Street, Homestead 33031-3314; sixth author: NIAS Genebank (MAFF), National Institute of Agrobiological Sciences, 2-1-2, Kannondai, Tsukuba, Ibaraki 305-8602 Japan; and seventh author: Bacterial Foodborne Pathogens and Mycology Research Unit, United States Department of Agriculture–Agricultural Research Service–NCAUR, 1815 N. University St., Peoria, IL 61604.

The primary objective of this study was to characterize Fusarium spp. associated with the economically devastating mango malformation disease (MMD) in Mexico. In all, 142 Fusarium strains were isolated from symptomatic mango inflorescences and vegetative tissues in eight geographically diverse Mexican states from 2002 through 2007. Initially, all the Mexican isolates were screened for genetic diversity using appolymerase chain reaction and random amplified polymorphic DNA markers and were grouped into seven distinct genotypes. Based on results of these analyses, evolutionary relationships and species limits of the genetically diverse MMD-associated Fusarium spp. were investigated using multilocus DNA sequence data and phylogenetic species recognition. Maximum parsimony analyses of a five-locus data set comprising 5.8 kb of aligned DNA sequence data indicated that at least nine phylogenetically distinct Fusarium spp. within the Gibberella fujikuroi species complex are associated with MMD, including one species within the African clade (Fusarium pseudocircinatum), two species within the Asian clade (F. mangiferae and F. proliferatum), and at least six species within the American clade (F. sterilihyphosum and five undescribed Fusarium spp.). Molecular phylogenetic analyses indicate that a novel genealogically exclusive lineage within the American clade was the predominant MMD associate in Mexico. This new Fusarium sp. caused MMD and could be distinguished from all other known species morphologically by the production of mostly sterile, coiled hyphae which are typically associated with sporodochial conidiophores together with unbranched or sparsely branched aerial conidiophores. Koch's postulates were completed for isolates of the new species on nucellar seedlings of mango cv. Ataulfo. This pathogen is formally described herein as F. mexicanum.

Additional keywords: Fusarium moniliforme, F. subglutinans, genealogical concordance phylogenetic species recognition (GCPSR), Mangifera indica.