Morphology, Phenotype, and Molecular Identification of Clinical and Environmental Fusarium solani Species Complex Isolates from Malaysia

Abstract

Fusarium infections in humans (fusariosis) and in economically important plants involve species of several Fusarium species complexes. Species of the Fusarium solani species complex (FSSC) are the most frequent cause of human fusariosis. The FSSC comprises more than 60 closely related species that can be separated into three major clades by multi-locus sequence typing (MLST) using translation elongation factor 1-alpha (TEF1-α) and RNA polymerase II (RPB2) DNA sequences. The MLST nomenclature for clade 3 of the FSSC assigns numbers to species types (e.g., FSSC 2) and lowercase letters to identify unique haplotypes. The aim of this study was to analyse the genotypic and phenotypic characteristics of 15 environmental and 15 clinical FSSC isolates from Malaysia. MLST was used for the genotypic characterisation of FSSC isolates from various locations within Malaysia, which was complemented by their morphological characterisation on potato dextrose and carnation leaf agar. MLST identified eight different FSSC species: thirteen Fusarium keratoplasticum (i.e., FSSC 2), six Fusarium suttonianum (FSSC 20), five Fusarium falciforme (FSSC 3+4), two Fusarium cyanescens (FSSC 27), and one each of Fusarium petroliphilum (FSSC 1), Fusarium waltergamsii (FSSC 7), Fusarium sp. (FSSC 12), and Fusarium striatum (FSSC 21). Consistent with previous reports from Malaysia, most (11 of 15) clinical FSSC isolates were F. keratoplasticum and the majority (9 of 15) of environmental isolates were F. suttonianum (5) or F. falciforme (4) strains. The taxonomic relationships of the isolates were resolved phylogenetically. The eight Fusarium species also showed distinct morphological characteristics, but these were less clearly defined and reached across species boundaries. Although TEF1-α and RPB2 sequences were sufficient for the species identification of most FSSC isolates, a more precise MLST scheme needs to be established to reliably assign individual isolates of the species-rich FSSC to their geographically-, epidemiologically-, and host-associated sub-lineages.

Identification and Characterization of Fusarium Species Causing Watermelon Fruit Rot in Northern Thailand

“…A phylogenetic tree of the F. solani species complex is shown in Figure 3 . Our phylogenetic tree was constructed with the aim of being similar to those in previous phylogenetic studies [ 50 , 55 , 56 ]. The phylogenetic tree successfully assigned the two fungal isolates (SDBR-CMU463 and SDBR-CMU464) assessed in this investigation within the same clade of F. paranaense , which consisted of the type species CML 1830.…”

“…In this study, two isolates of F. compactum (SDBR-CMU461 and SDBR-CMU462) and two isolates of F. paranaense (SDBR-CMU463 and SDBR-CMU464) were isolated from fruit rot lesions on watermelons from northern Thailand. These four fungal isolates were identified using a combination of their morphological features and phylogenetic analysis of multiple genes, according to the identification techniques used in previous studies [ 35 , 36 , 37 , 38 , 50 , 55 , 56 ]. Prior to this study, F. compactum and F. paranaense had previously been identified as plant pathogens; for example, F. compactum was found to be the cause of leaf spot on sweet cherry ( Prunus avium L.) [ 69 ] and leaf blight on maize ( Zea mays L.) [ 70 ] in China, root rot of banana ( Musa sp.)…”

Pathogenicity, Host Resistance, and Genetic Diversity of Fusarium Species under Controlled Conditions from Soybean in Canada

“…Non-negligible differences in species identification by morphology and molecular phylogenetics have been reported in other recent studies, illustrating the need to integrate both morphological characteristics and molecular technologies in the identification of Fusarium spp. [98,99].…”

Identification and Pathogenicity of Fusarium Isolated from Soybean in Poland

“…In the case of our study, the TEF1 and RPB2 sequences proved to be sufficient for the unambiguous assignment of the nineteen isolates to four Fusarium species. Many recent studies have used the same two regions for Fusarium species identification [ 7 , 8 , 38 , 39 , 40 , 41 , 42 , 43 ]. Our research has confirmed that sequencing is essential for distinguishing Fusarium species.…”