Three new genera in Chytridiales from aquatic habitats in Argentina

Abstract

Sampling for chytrids in a variety of habitats has resulted in pure cultures that when analyzed have yielded hypotheses of relationships based on molecular and zoospore ultrastructural markers. To extend our understanding of diversity of Chytridiales in eastern Argentina and USA, we isolated and examined the morphology, ultrastructure and 28S and ITS1-5.8S-ITS2 rDNA sequences of numerous chytrids from aquatic habitats from these two regions. Three family-level lineages (Chytridiaceae, Chytriomycetaceae, family incertae sedis) are represented in our molecular phylogeny, and three new genera (Avachytrium, Odontochytrium in Chytriomycetaceae, Delfinachytrium in family incertae sedis) are described. These findings of new genera and species emphasize the potential for discovery of additional diversity.

Hypothesized evolutionary trends in zoospore ultrastructural characters in Chytridiales (Chytridiomycota)

“…Maximum parsimony (MP) trees were generated using PAUPRat (Sikes and Lewis 2001), and bootstrap values were generated as heuristic searches with 500 replicates, each with 10 random-addition replicates. Maximum likelihood (ML) phylogenetic trees were constructed as described (Vélez et al 2011). Modeltest 3.7 (Posada and Crandall 1998) was used to determine the best model of base substitution and GARLI 0.951 (Zwikl 2006) was used to assess maximum likelihood.…”

“…Partial 28S rDNA (LSU) sequences for all ingroup and outgroup isolates were generated as described by Letcher and Powell (2005a) or obtained from GenBank. Molecular phylogenetic analyses were performed as described by Vélez et al (2011). In summary, partial LSU sequences (794-850 bp) were aligned in Clustal X followed by manual adjustments.…”

“…Within three of these orders, ultrastructural analyses have revealed tremendous unrealized zoospore diversity, such that we now know of 18 zoospore subtypes in Rhizophydiales (Letcher and Powell 2005a;Letcher et al 2006Letcher et al , 2008aLetcher et al , b, 2012bLongcore et al 1999;Powell and Roychoudhury 1992;Powell et al 2011), six subtypes in Polychytriales (Longcore 1993, Longcore andSimmons 2012) and four subtypes in Lobulomycetales (Simmons et al , 2012. Here we examine previously published and new zoospore ultrastructural data from isolates in Chytridiales (sensu Vélez et al 2011) and reveal multiple zoospore subtypes in the order. From the ultrastructural data combined with the molecularbased phylogeny, we hypothesize that ultrastructural character state evolution within the ordinal lineage tends to go from numerous organelles to fewer and less complex organelles.…”

“…The collaborative Assembling the Fungal Tree of Life (AFTOL I) project resulted in a molecular phylogeny of Chytridiomycota (James et al 2006) containing several monophyletic lineages, seven of which were considered as clades of a polyphyletic Chytridiales. Subsequent expanded molecular and ultrastructural analyses of five of those clades resulted in delineation of the monophyletic orders Chytridiales (Vélez et al 2011), Cladochytriales (Mozley-Standridge et al 2009), Lobulomycetales ), Polychytriales (Longcore and Simmons 2012) and Rhizophydiales (Letcher et al 2006). Within three of these orders, ultrastructural analyses have revealed tremendous unrealized zoospore diversity, such that we now know of 18 zoospore subtypes in Rhizophydiales (Letcher and Powell 2005a;Letcher et al 2006Letcher et al , 2008aLetcher et al , b, 2012bLongcore et al 1999;Powell and Roychoudhury 1992;Powell et al 2011), six subtypes in Polychytriales (Longcore 1993, Longcore andSimmons 2012) and four subtypes in Lobulomycetales (Simmons et al , 2012.…”

“…Subsequent expanded molecular and ultrastructural analyses of five of those clades resulted in delineation of the monophyletic orders Chytridiales (Vélez et al 2011), Cladochytriales (Mozley-Standridge et al 2009), Lobulomycetales ), Polychytriales (Longcore and Simmons 2012) and Rhizophydiales (Letcher et al 2006). Within three of these orders, ultrastructural analyses have revealed tremendous unrealized zoospore diversity, such that we now know of 18 zoospore subtypes in Rhizophydiales (Letcher and Powell 2005a;Letcher et al 2006Letcher et al , 2008aLetcher et al , b, 2012bLongcore et al 1999;Powell and Roychoudhury 1992;Powell et al 2011), six subtypes in Polychytriales (Longcore 1993, Longcore andSimmons 2012) and four subtypes in Lobulomycetales (Simmons et al , 2012. Here we examine previously published and new zoospore ultrastructural data from isolates in Chytridiales (sensu Vélez et al 2011) and reveal multiple zoospore subtypes in the order.…”