Taxonomy and diversity of basal fungi with an emphasis on Mucorales and Chytridiomycota

Name: Vedprakash Godadhar Hurdeal

keyword: Basal Fungi

MeSH: Fungi -- 304218

Classification :.DDC: e-Theses

; Evolution of Characters

MeSH: Fungi -- Classification -- 52208

MeSH: Biology -- Classification -- 59923

MeSH: Mucorales -- 304219

MeSH: Phylogeny -- 304220

LCSH: Fungi -- 304218

LCSH: Fungi -- Classification -- 52208

LCSH: Biology -- Classification -- 59923

LCSH: Mucorales -- 304219

LCSH: Phylogeny -- 304220

Abstract: Early diverging fungal lineages, also known as basal fungi, cluster at the base of the fungal tree of life relative to Dikarya. These lineages encompass diverse groups and can be broadly classified into two categories: zoosporic and zygosporic fungi. Among these lineages, Mucoromycota and Chytridiomycota emerge as the most species-rich groups and hold pivotal ecological significance in various ecosystems. Mucoromycota, encompassing taxa such as Mucorales, exhibit a cosmopolitan distribution and commonly inhabit soil, decaying plant matter, and animal dung. While some species function as post-harvest pathogens in stored fruits and cereals, others display facultative fungal parasitism and opportunistic pathogenicity in humans. Mucoromycota comprises taxa responsible for the severe disease mucormycosis, particularly affecting immunocompromised individuals. Within Mucoromycota, the order Mucorales is the most diverse, comprising 55 genera and over 300 species. However, for the majority of these species, their ecological roles and geographic distributions remain poorly understood. The Chytridiomycota, a phylum of zoosporic eufungi, thrive in a variety of terrestrial, freshwater, and oceanic habitats. They play a prominent role as saprobes and parasites of phytoplankton, particularly in aquatic networks. Rhizophydiales is one of 15 orders in the Chytridiomycota. Prior to the advent of molecular techniques for inferring evolutionary relationships, various morphology-based species were assigned to the genus Rhizophydium. This taxonomic grouping presented challenges due to its broad definition, encompassing over 200 described species. However, the integration of ultrastructural characters with molecular phylogenetics facilitated the revision of the Rhizophydium clade, subsequently elevated to the ordinal level as Rhizophydiales. Despite the progress made in the taxonomy of Rhizophydiales, the classification of many species within this order, which relied solely on morphology, continues to pose challenges. This study led to the identification of 16 novel taxa belonging to the Mucoralean group, encompassing, eight Absidia, six Mucor, one Backusella and one Cunninghamella species. The introduction of the new species was based on comprehensive polyphasic approach, incorporating morpho-physiological data and phylogenetic analyses. In cases where protein-coding genes were available and could be amplified, genealogical concordance phylogenetic species recognition was also used for species delimitation. Moreover, this investigation yielded significant findings in terms of geographical records, highlighting new occurrences within Absidia, Cunninghamella, Gongronella, Lichtheimia, Mucor, Rhizopus, and Saksenaea. Furthermore, this study led to the discovery of chytrids belonging to 7 genera from Thailand. Phylogenetic analyses placed the isolates within Rhizophydiales and Chytridiales. A tripartite approach that employed phylogeny, ITS genetic distances, and Poisson tree processes (PTP) delineated taxonomic novelties (new species) within each taxon. The results of these comprehensive approaches strongly suggested the existence of multiple species within each genus. Consequently, this study introduced two new species of Angulomyces, one species of Alphamyces, four species of Gorgonomyces, one species of Pateramyces and three species of Terramyces. Intrageneric genetic distances in the internal transcribed spacer (ITS) ranged between 1.5 and 20%. Morphological differences could be observed in the size of sporangia, zoospores, and number of discharge papilla. Two new geographical records of Chytriomyces hyalinus and Delfinachytrium mesopotamicum are reported as well. This study contributes to the knowledge of chytrids, an understudied group in Thailand and worldwide. Phylogenetic assessment of Mucorales revealed significant taxonomic gaps that required attention. To address this, a comprehensive analysis utilizing a concatenated dataset of ITS, LSU, SSU, ACT, and EF-1α, accompanied by ancestral state reconstruction, was conducted. The results underscored the necessity for several amendments to ensure adherence to the principles of monophyly and the phylogenetic species concept, while also considering morphological characteristics. Consequently, this study proposes multiple amendments and introduces three novel genera within the Rhizopodaceae, alongside various new combinations. Furthermore, analyses employing Reconstruct Ancestral State in Phylogenies (RASP) were performed on spore-bearing and producing structures (traits), revealing that the most recent common ancestor likely possessed a sporangium and that the presence of sporangiolum or merosporangium was independently acquired. These findings significantly contribute to our understanding of the evolutionary history and morphological diversification within Mucorales. The taxonomic classification of freshwater fungi has been comprehensively revised and updated. Through meticulous examination of diverse taxonomic papers and biodiversity studies, this study presents a comprehensive list comprising 684 freshwater fungal species. These species belong to 11 phyla, namely Chytridiomycota, Rozellomycota, Blastocladiomycota, Monoblepharomycota, Mucoromycota, Aphelidiomycota, Entomophthoromycota, Mortierellomycota, Olpidiomycota, Zoopagomycota, and Sanchytriomycota.

Mae Fah Luang University. Learning Resources and Educational Media Center

Address: CHIANG RAI

Email: library@mfu.ac.th

Name: Gentekaki Eleni

Role: Advisor

Created: 2022

Modified: 2023-06-29

Issued: 2023-06-29

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: e-Theses

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Biological Sciences

Grantor: Mae Fah Luang University

©copyrights Mae Fah Luang University

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