An expanded multilocus phylogeny does not resolve morphological species within the small-sporedAlternariaspecies complex

Abstract

Small-spored Alternaria species are a taxonomically challenging group of fungi with few morphological or molecular characters that allow unambiguous discrimination among taxa. The protein-coding genes most commonly employed in fungal systematics are invariant among these taxa, so noncoding, anonymous regions of the genome were developed to assess evolutionary relationships among these organisms. Nineteen sequence-characterized amplified regions (SCAR) were screened for phylogenetic utility by comparing sequences among reference isolates of small-spored Alternaria species. Five of nineteen loci were consistently amplifiable and had sufficient phylogenetic signal. Phylogenetic analyses were performed with 150 small-spored Alternaria isolates using sequence data from an endopolygalacturonase gene and two anonymous loci. Associations among phylogenetic lineage, morphological classification, geography and host were evaluated for use as practical taxonomic characters. Samples included isolates from citrus in Florida, pistachio in California, desert plants in Arizona, walnuts in France/Italy and apples in South Africa. No associations were found between host or geographic associations and phylogenetic lineage, indicating that these characters were not useful for cladistic classification of small-spored Alternaria. Similarly strict congruence between morphology and phylogenetic lineage was not found among isolates grouped morphologically with A. alternata or A. tenuissima. In contrast 34 isolates grouped morphologically with A. arborescens fell into discrete clades for all datasets. Although 5-9 well supported clades were evident among isolates, it is currently unclear if these clades should be considered phylogenetic species or emerging evolutionary lineages within the phylogenetically defined alternata species-group.

Especies de Alternaria de La Sabana de Bogotá, Colombia

“…Se ha discutido su papel como endófito (Aly et al, 2008; Lahlali y Hijri, 2010; Kaur et al, 2013), saprófito o parásito de plantas vivas (Pitt y Hocking, 1997). La base de datos de hongos del Departamento de Agricultura de los Estados Unidos (USDA) presenta 4000 asociaciones de Alternaria con diferentes hospederos (Farr et al, 2013), convirtiéndose en uno de los géneros de hongos con más amplio rango de hospederos como patógeno de plantas (Andrew et al, 2009). Farr et al (1989), posicionan a Alternaria en el décimo lugar en términos del número total de plantas hospederas.…”

Fungal Diagnostics

“…These patients are susceptible to infections from fungi rarely seen, or never reported as a human pathogen, which can cause identification problems for even the most experienced mycologists. Whereas mycologists in the past needed to be able to identify 50 commonly encountered fungi, and 300 total fungi that were pathogenic for humans, the number of potential fungal pathogens is likely many times what is described in textbooks, and will continue to grow as the severely immunosuppressed patient population continues to grow (Ajello and Hay 1998;Collier et al 1998;Andrew et al 2009). …”

Differential gene expression in Alternaria gaisen exposed to dark and light

“…Rossman (2007) described the rationale for selection of ITS for barcoding the fungi but acknowledged that ITS does not work for some clearly recognizable species, and Seifert (2009) noted that additional barcode genes may be necessary for such fungi. Molecular studies using ITS rDNA (Kusaba and Tsuge 1995), protein coding housekeeping genes (Peever et al 2004), and anonymous open reading frames (ORF; Andrew et al 2009) sequence data, rDNA RFLPs (Kusaba and Tsuge 1994), and IGS restriction mapping (Hong et al 2005) from the smallspored Alternaria have demonstrated a low level of variability that do not support most segregations resulting from morphological, chemotaxonomic, and DNA fingerprinting studies. Kusaba and Tsuge (1995) went as far as to conclude that the small-spored species are all intraspecific variants of one species, A. alternata.…”