Bipolar, not tetrapolar: mating system determination in Inonotus hispidus through genomic and phenotypic analysis

Area of Science:

• Mycology
• Plant Science
• Biotechnology

Background:

• Inonotus hispidus is a valuable medicinal mushroom with growing production.
• Strain improvement is vital for industry progress.
• Identifying homokaryotic strains is challenging due to the absence of clamp connections.

Purpose of the Study:

• To confirm the mating system of Inonotus hispidus.
• To develop reliable methods for identifying homokaryotic strains.
• To revise traditional concepts of mycelial types in this species.

Main Methods:

• Genome sequencing and homologous gene BLAST analysis to identify mating type loci.
• Distinguishing homokaryotic and heterokaryotic strains using sequence differences.
• Traditional mating tests combined with growth rate and antagonism observations.

Main Results:

• Confirmed multinucleate nature of both heterokaryotic and homokaryotic mycelia.
• Identified mating type loci and elucidated a bipolar mating system, refuting tetrapolar system reports.
• Demonstrated growth rate and antagonism as reliable indicators for homokaryon identification.

Conclusions:

• Established a reliable method for homokaryotic strain identification in Inonotus hispidus.
• Systematically characterized the bipolar mating system for the first time.
• Provided a scientific foundation for understanding the life cycle and developing new germplasms.