Transcriptome Comparison between Two Strains of Ustilago esculenta during the Mating

Area of Science:

• Plant pathology
• Mycology
• Fungal genetics

Background:

• Ustilago esculenta, an obligate pathogen of Zizania latifolia, causes gall formation.
• MT-type U. esculenta exhibits unique proliferation and host-offspring infection strategies, differing from T-type.
• Degeneration in telispore production, haploid life, and cuticle penetration may occur in MT-type.

Purpose of the Study:

• To investigate transcriptome changes during the mating of T- and MT-type U. esculenta.
• To compare mating processes and identify key genes and secreted proteins involved in U. esculenta infection.
• To validate the function of candidate secreted proteins using knock-out mutants.

Main Methods:

• Comparative transcriptome analysis of T- and MT-type U. esculenta mating.
• Gene knock-out experiments to assess the function of specific secreted proteins (e.g., g6161, g943, g4344).
• Analysis of co-expression modules, particularly the purple module enriched with secreted protein genes.

Main Results:

• MT-type U. esculenta senses mating signals but exhibits delayed conjunction tube formation and cytoplasmic fusion compared to T-type.
• A purple co-expression module, rich in secreted protein genes, is upregulated late in T-type mating, suggesting a role in infection.
• Knock-out of g6161 (xylanase) attenuated symptoms, while g943 and g4344 knock-outs completely blocked early-stage infection.

Conclusions:

• MT-type U. esculenta mating is slower than T-type, despite similar environmental sensing capabilities.
• Secreted proteins, particularly those in the purple co-expression module, are crucial for U. esculenta infection.
• g943 and g4344 represent promising candidate effectors for understanding U. esculenta pathogenesis.