Combined approach of morphological and molecular diagnosis of Fusaria spp. Causing diseases in crop plants

Abstract

Fusarium species cause a huge range of diseases on an extraordinary range of host plants. Fusarium taxonomy has been plagued by changing species concepts, with as few as nine or well over 1,000 species being recognized by various taxonomists during the past 100 years, depending on the species concept employed. The possible outcome from morphological diagnosis alone may identify quickly when the number of species associated with particular host or disease symptoms is relatively limited. Morphological characters frequently are homoplastic, and the circumscription of taxa, based on the size and shape of conidia and conidiophores and the color and texture of colonies, has resulted in an underestimation of species diversity within Fusarium. Phylogenetic species recognition, based on DNA sequence data from multiple loci, allows greater numbers of species to be distinguished than in the exclusive use of morphological features. Closely related species may show considerable divergence in IGS, often reflecting both length and sequence variation; length and restriction site variation may even occur within the rDNA of an individual in some fungi.