Morphogenesis in Mucor mucedo: mutations affecting gamone response and organ differentiation

Area of Science:

• Mycology
• Molecular Biology
• Developmental Biology

Background:

• Trisporic acid (TA) is a key signaling molecule in Mucor mucedo reproduction, mediating zygophore formation.
• Understanding the genetic regulation of zygophore development is crucial for comprehending sexual reproduction in Mucorales.

Purpose of the Study:

• To isolate and characterize mutants of Mucor mucedo affected in trisporic acid (TA) mediated zygophore formation.
• To elucidate the role of TA and its precursor (P) in the regulation of zygophore development.

Main Methods:

• Isolation and phenotypic analysis of Mucor mucedo mutants exhibiting altered zygophore formation (cold-sensitive, temperature-sensitive, unstable zygophores).
• Assessment of mutant responses to varying concentrations of trisporic acid (TA) and its precursor (P).

Main Results:

• Isolated mutants with defects in zygophore formation, including cold-sensitive (cs), temperature-sensitive (ts), and unstable zygophores (Zst-).
• Deduced a sequential model for mycelial competence in organ formation based on pleiotropic phenotypes.
• Demonstrated that TA acts as a growth substance on a transient competence state.
• Showed that reduced response to TA correlates with reduced response to its precursor P, suggesting P conversion to TA is necessary.
• Identified a mutant where high TA concentrations promote zygophore formation, while high P concentrations inhibit it, indicating P may antagonize TA.

Conclusions:

• Trisporic acid (TA) is essential for zygophore growth, acting on a specific transient state of mycelial competence.
• The TA precursor (P) must be converted to TA to induce zygophore growth.
• P exhibits antagonistic activity towards TA in regulating zygophore development, adding complexity to the signaling pathway.