Related Experiment Video
Updated: Jul 5, 2026
05:34
Sexual Crosses with the Mucoromycete Phycomyces blakesleeanus
Published on: June 6, 2025
Sex in smut fungi: Structure, function and evolution of mating-type complexes
Guus Bakkeren1, Jörg Kämper, Jan Schirawski
1Agriculture & Agri-Food Canada, Pacific Agri-Food Research Centre, Summerland, BC, Canada.
Fungal Genetics and Biology : FG & B
|May 27, 2008
Summary
Smut fungi require cell fusion for pathogenicity, regulated by conserved mating-type genes. Structural variations in these genes across species suggest independent evolutionary shifts from tetrapolar to bipolar mating systems.
Area of Science:
- Plant Pathology
- Mycology
- Evolutionary Biology
Background:
- Smut fungi are basidiomycete pathogens impacting cereal crops.
- Pathogenicity requires compatible mating-type cells to fuse.
- Fusion and pathogenicity are controlled by conserved genes within 'a' and 'b' loci.
Purpose of the Study:
- To review the functions of mating-type complexes in Ustilago maydis.
- To analyze the structural evolution of mating-type loci in smut fungi.
- To investigate the evolutionary transition from tetrapolar to bipolar mating behavior.
Main Methods:
- Sequence comparison of mating-type loci across diverse smut and related fungi.
- Review of established knowledge on mating-type complex functions in Ustilago maydis.
Main Results:
- Mating-type loci ('a' and 'b') harbor conserved genes regulating fusion and pathogenicity.
- Significant structural differences were observed in mating-type loci among various fungal species.
- These structural variations indicate a potential evolutionary trend from tetrapolar to bipolar mating systems.
Conclusions:
- The structure of mating-type loci is highly variable across smut fungi.
- Evolutionary transitions from tetrapolar to bipolar mating likely occurred multiple times independently.
- Understanding these loci is crucial for controlling smut fungal diseases in agriculture.
Related Concept Videos
01:29Overview of Fungi
Fungi are a diverse group of eukaryotes more closely related to animals than other eukaryotes. Fungal cell walls comprise chitin, a polysaccharide that provides structural strength, and glucans, which contribute to flexibility and integrity. Other polysaccharides, such as mannans and galactosans, may supplement or replace chitin in some fungi. These adaptations, along with their preference for acidic environments and tolerance for high osmotic pressure, enable fungi to thrive in various...
01:28Fungal Phylum Ascomycota
Phylum Ascomycota, a major division within the subkingdom Dikarya, comprises a diverse range of fungal species, including both unicellular yeasts and filamentous molds such as Aspergillus and Penicillium. These fungi thrive in a variety of habitats, from aquatic ecosystems to terrestrial environments, playing crucial ecological and economic roles.Morphology and ReproductionThe defining characteristic of Ascomycetes, commonly referred to as sac fungi, is the ascus—a sac-like structure that...
01:28Yeast Signaling
Yeasts are single-celled organisms, but unlike bacteria, they are eukaryotes (cells with a nucleus). Cell signaling in yeast is similar to signaling in other eukaryotic cells. A ligand, such as a protein or a small molecule released from a yeast cell, attaches to a receptor on the cell surface. The binding stimulates second-messenger kinases to activate or inactivate transcription factors that further regulate gene expression. Many of the yeast intracellular signaling cascades have similar...
01:29Fungal Group Zygomycota
Zygomycota, previously classified as a distinct fungal group, are primarily terrestrial, saprophytic molds that play a crucial role as decomposers. Recent phylogenetic studies have revealed that these fungi are now divided into two major clades — Mucoromycota, which includes many symbiotic species, and Zoopagomycota, which primarily consists of parasitic and pathogenic fungi. These groups exhibit distinct ecological roles and reproductive strategies while sharing key structural and...
01:26Fungal Phylum Basidiomycota
Basidiomycota is a diverse phylum of fungi that includes ecologically significant decomposers such as white rot fungi, symbionts like mycorrhizal fungi, plant pathogens such as rusts and smuts, and edible species like Agaricus bisporus (the common button mushroom). These fungi play crucial roles in nutrient cycling, symbiotic relationships, and even human health. Their defining feature is the basidium, a microscopic club-shaped structure responsible for producing basidiospores.Fruiting Bodies...
01:27Diversity of Protists IV
Amoebozoa represent a diverse group of terrestrial and aquatic protists that utilize lobe-shaped pseudopodia for locomotion and feeding. This characteristic differentiates them from the Rhizaria, which possess threadlike pseudopodia. The primary classifications within Amoebozoa include gymnamoebas, entamoebas, and the plasmodial and cellular slime molds. Phylogenetic evidence indicates that Amoebozoa diverged from a lineage that ultimately gave rise to fungi and animals.Gymnamoebas and...