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Published on: June 6, 2025
Structure, function, and phylogeny of the mating locus in the Rhizopus oryzae complex
Andrii P Gryganskyi1, Soo Chan Lee, Anastasia P Litvintseva
1Department of Biology, Duke University, Durham, North Carolina, United States of America. apg10@duke.edu
Plos One
|December 15, 2010
Summary
The Rhizopus oryzae complex has a conserved mating locus structure, with two distinct species, R. oryzae and R. delemar, exhibiting evidence of outcrossing despite limited in vitro sexual reproduction.
Area of Science:
- Mycology
- Genetics
- Evolutionary Biology
Background:
- The Rhizopus oryzae species complex comprises cosmopolitan fungi with dual roles as beneficial fermenters and opportunistic pathogens.
- Despite a known heterothallic mating system, sexual reproduction in R. oryzae is rarely observed, and its mating locus genetics remain uncharacterized.
Purpose of the Study:
- To investigate the mating behavior and genetic structure of the mating locus in 54 isolates of the R. oryzae complex.
- To determine the population structure and mating system of R. oryzae and R. delemar.
Main Methods:
- Comparative analysis of mating locus structure across 54 R. oryzae complex isolates.
- Phylogenetic analyses using multiple genes (mating loci, rDNA, RPB2, LDH).
- In vitro crosses between tester strains and R. oryzae/R. delemar isolates.
Main Results:
- A conserved mating locus organization was identified, similar to other zygomycetes, with distinct alleles for plus and minus mating types.
- Phylogenetic analyses revealed two cryptic species: R. oryzae sensu stricto and R. delemar.
- Evidence for outcrossing and random mating was found within each species, supported by discordant gene phylogenies and a 50:50 mating type ratio.
Conclusions:
- The Rhizopus oryzae complex harbors two cryptic species with conserved sex locus structures.
- Despite challenges in in vitro mating, genetic data strongly suggest a functional sexual cycle and outcrossing population structure in both R. oryzae and R. delemar.
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