CHRONOLOGY OF THE TAXONOMY AND CLADISTICS OF GLOMEROMYCETES

Abstract

Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs of higher plants and constitute one of the most widespread groups of soil microorganisms. Classification, taxonomy and description of evolutionary relationships among AMF have been a fundamental part on the study of such organisms. Development of this knowledge can be separated into three major stages starting from the first reported observations of these microorganisms. The first stage corresponds to the recognition of morphological diversity among the species clustered in the genera Endogone (Zygomycota), and its separation into the AMF genera Gigaspora, Acaulospora, Glomus and Sclerocystis, and the non-mycorrhizal Modicella, Glaziella and Endogone, all of these subordinated to Endogonaceae. The second stage involves the study of common morphological features that resulted from the separation of AMF species in a monophyletic group at the rank of an order (Glomales). Finally, the third stage comprises most recent studies that rely on the use of molecular biology tools coupled with observation of morphological features. One of the most significant contributions of this period was placing AMF species in a higher taxa rank and grouping the species in the Glomales Order into the phylum Glomeromycota. This review addresses these three stages in detail, and provides a general view of the distinct taxonomical changes in AMF classification.