TY - JOUR

T1 - The Chytrid-like Parasites of Algae Amoeboradix gromovi gen. et sp. nov. and Sanchytrium tribonematis Belong to a New Fungal Lineage

AU - Karpov, Sergey A.

AU - López-García, Purificación

AU - Mamkaeva, Maria A.

AU - Klimov, Vladimir I.

AU - Vishnyakov, Andrey E.

AU - Tcvetkova, Victoria S.

AU - Moreira, David

PY - 2018/2/1

Y1 - 2018/2/1

N2 - Fungi encompass, in addition to classically well-studied lineages, an ever-expanding diversity of poorly known lineages including zoosporic chytrid-like parasites. Here, we formally describe Amoeboradix gromovi gen. et sp. nov. comprising a set of closely related strains of chytrid-like parasites of the yellow-green alga Tribonema gayanum unusually endowed with amoeboid zoospores. Morphological and ultrastructural features of A. gromovi observed by light and transmission electron microscopy recall previous descriptions of Rhizophydium anatropum. A. gromovi exhibits one of the longest kinetosomes known in eukaryotes, composed of microtubular singlets or doublets. To carry out molecular phylogenetic analysis and validate the identification of different life cycle stages, we amplified 18S rRNA genes from three A. gromovi strains infecting T. gayanum cultures, single sporangia and single zoospores. Molecular phylogenetic analyses of 18S+28S rRNA concatenated genes of the type strain revealed that A. gromovi is closely related to the recently described species Sanchytrium tribonematis, another parasite of Tribonema that had been tentatively classified within Monoblepharidomycetes. However, our phylogenetic analysis with an extended taxon sampling did not show any particular affinity of Amoeboradix and Sanchytrium with described fungal taxa. Therefore, Amoeboradix gromovi and Sanchytrium tribonematis likely represent a new divergent taxon that remains incertae sedis within Fungi.

AB - Fungi encompass, in addition to classically well-studied lineages, an ever-expanding diversity of poorly known lineages including zoosporic chytrid-like parasites. Here, we formally describe Amoeboradix gromovi gen. et sp. nov. comprising a set of closely related strains of chytrid-like parasites of the yellow-green alga Tribonema gayanum unusually endowed with amoeboid zoospores. Morphological and ultrastructural features of A. gromovi observed by light and transmission electron microscopy recall previous descriptions of Rhizophydium anatropum. A. gromovi exhibits one of the longest kinetosomes known in eukaryotes, composed of microtubular singlets or doublets. To carry out molecular phylogenetic analysis and validate the identification of different life cycle stages, we amplified 18S rRNA genes from three A. gromovi strains infecting T. gayanum cultures, single sporangia and single zoospores. Molecular phylogenetic analyses of 18S+28S rRNA concatenated genes of the type strain revealed that A. gromovi is closely related to the recently described species Sanchytrium tribonematis, another parasite of Tribonema that had been tentatively classified within Monoblepharidomycetes. However, our phylogenetic analysis with an extended taxon sampling did not show any particular affinity of Amoeboradix and Sanchytrium with described fungal taxa. Therefore, Amoeboradix gromovi and Sanchytrium tribonematis likely represent a new divergent taxon that remains incertae sedis within Fungi.

KW - amoeboid zoospore

KW - kinetosome.

KW - life cycle

KW - molecular phylogeny

KW - Parasites of algae

KW - ultrastructure

UR - http://www.scopus.com/inward/record.url?scp=85042374403&partnerID=8YFLogxK

U2 - 10.1016/j.protis.2017.11.002

DO - 10.1016/j.protis.2017.11.002

M3 - Article

AN - SCOPUS:85042374403

VL - 169

SP - 122

EP - 140

JO - Protist

JF - Protist

SN - 1434-4610

IS - 1

ER -