Fig A) Mucor mucedo multispored sporangia borne terminally on aerial sporangiophores. Fig B) M. mucedo zygospore held between opposed suspensors. Images by Kerry O'Donnell.

Mucor mucedo NRRL 3635 is a zygomycete fungus classified in the family Mucoraceae [Order Mucorales, Phylum Mucoromycota; Spatafora et al. 2016].  It was deposited in the Westerdijk Fungal Biodiversity Institute (formerly CBS-KNAW) as CBS 144.24 by H. Burgeff in 1924, who determined through mating experiments that this strain represents the [+] mating type of this heterothallic or self-sterile species.  Using M. mucedo as a model organism, Burgeff discovered trisporic acid, a volatile compound derived from β-carotene, the first mating pheromone characterized in the fungi (Burgeff 1924; Lee and Heitman 2015).  During the asexual phase of the life cycle, M. mucedo produces multispored sporangia that are borne terminally on aerial sporangiophores (Fig. A).  When the sexually compatible NRRL 3635 [+] and NRRL 3634 [–] strains are paired on suitable agar media, hyphal fusion leads to the production of an ornamented zygospore between opposed suspensors (Fig. B).  Molecular phylogenetic studies have shown that Mucor and the Mucoraceae are polyphyletic as currently circumscribed (O’Donnell et al. 2000; Walther et al. 2013).  The whole-genome sequence of this early diverging mucoralean mold was generated within the framework of the 1000 Fungal Genome Project and the ZyGoLife project, which aim to advance our knowledge of fungal evolution and genomics of early diverging fungi.

References:

Burgeff H. 1924. Untersuchungen über Sexualitat und Parasitismus bei Mucorineen. Verlag von Gustav Fischer.

Lee SC, Heitman J. 2015. Sex in the mucoralean fungi. Mycoses 57:18─24.

O’Donnell K, Lutzoni F, Ward TJ, Benny GL. 2000. Evolutionary relationships among mucoralean fungi (Zygomycota): Evidence for family polyphyly on a large scale. Mycologia 93:286─296.

Spatafora JW, Chang Y, Benny GL, Lazarus K, Smith ME, Berbee ML, Bonito G, Corradi N, Grigoriev I, Gryganskyi A, James TY, O’Donnell K, Roberson RW, Taylor TN, Uehling J, Vilgalys R, White MM, Stajich JE. 2016. A phylum-level phylogenetic classification of zygomycete fungi based on genome-scale data. Mycologia 108:1028─1046.

Walther G, Pawłowska J, Alastruey-Izquierdo A, Wrzosek M, Rodriguez-Tudela JL, Dolatabadi S, Chakrabarti A, de Hoog GS. 2013. DNA barcoding in Mucorales: an inventory of biodiversity. Persoonia 30:11–47.