Home • Polychytrium aggregatum JEL109 v1.0
Polychytrium aggregatum JEL109. Photo by D. Rabern Simmons.
Polychytrium aggregatum JEL109. Photo by D. Rabern Simmons.

Polychytrium aggregatum (JEL109) is a polycentric, inoperculate chytrid species cultured from chitin baiting of a water and detritus sample of Bryant’s Bog taken near the University of Michigan Biological Station in Cheboygan Co., Michigan on Sept 28, 1992. This species was first described by Libero Ajello in 1942 from a bog in New Jersey and was also reported by Ajello in Brazil in 1944. The hyphal-like rhizomycelium of the developing thallus gives rise to intercalary and terminal zoosporangia, varying from generally pyriform to occasionally tuberculate. In Fred Sparrow’s 1960 monograph Aquatic Phycomycetes, he concluded his discussion on the species with, “It is abundant in bogs in Northern Michigan where it is obtained on shrimp chitin bait.” Sparrow’s student Joyce E. Longcore took this to heart when, 32 years later, she isolated JEL109 on chitin bait from one of the sites Sparrow had investigated during his tenure as the Director of the University of Michigan Biological Station. A molecular phylogeny placed P. aggregatum JEL109 outside of the Chytridiales along with other genera of both polycentric and monocentric species (James et al. 2000). A distinct phylogenetic placement and zoospore ultrastructure of Polychytrium and the related genus Karlingiomyces was confirmed by additional studies (James et al. 2006). Longcore and Simmons (2012) examined the ultrastructure of this and related species and described the Polychytriales, with JEL109 representing the type species of the new order. This order has only 5 genera and 6 species discovered thus far and may be the earliest diverging lineage in Chytridiomycotina. Genomic comparisons across orders will elucidate the mechanisms of how polycentricity arose in multiple chytrid orders (Dee et al. 2015), along with helping us fully understand the ecological niche of this order, whose species tend to subside on chitin substrates.

References:

Dee, J. M., M. Mollicone, J. E. Longcore, R. W. Roberson, and M. L. Berbee (2015). Cytology and molecular phylogenetics of Monoblepharidomycetes provide evidence for multiple independent origins of the hyphal habit in the Fungi. Mycologia, 107: 710-728.

James, T. Y., D. Porter, C. A. Leander, R. Vilgalys, and J. E. Longcore. (2000). Molecular phylogenetics of the Chytridiomycota supports the utility of ultrastructural data in chytrid systematics. Canadian Journal of Botany 78: 336-350.

James, T. Y., P. M. Letcher, J. E. Longcore, S. E. Mozley-Standridge, D. Porter, M. J. Powell, G. W. Griffith, R. Vilgalys (2006). A molecular phylogeny of the flagellated Fungi (Chytridiomycota) and a proposal for a new phylum (Blastocladiomycota). Mycologia 98: 860-871.

Longcore, J. E., and D. R. Simmons (2012). The Polychytriales ord. nov. contains chitinophilic members of the rhizophlyctoid alliance. Mycologia 104: 276-294.