Dothistromin genes at multiple separate loci are regulated by AflR

Area of Science:

• Mycology
• Fungal Genetics
• Secondary Metabolite Biosynthesis

Background:

• Secondary metabolite genes in fungi are typically located in clusters.
• Dothistromin, a toxin produced by Dothistroma septosporum, is an exception, with its genes dispersed across the genome.
• Understanding the regulation of dispersed genes is crucial for comprehending fungal pathogenicity.

Purpose of the Study:

• To investigate the regulation of dispersed dothistromin biosynthesis genes in Dothistroma septosporum.
• To identify the complete set of dothistromin production genes and their regulatory mechanisms.
• To explore the evolutionary implications of fragmented gene clusters in fungal pathogens.

Main Methods:

• Genome sequencing of Dothistroma septosporum.
• Gene knockout experiments, specifically targeting the AflR gene (ΔDsAflR).
• Gene expression analysis using quantitative methods.

Main Results:

• Most dothistromin biosynthesis genes are spread over six loci on chromosome 12, not correlated with telomere distance.
• The regulatory gene AflR controls the expression of these dispersed genes.
• Knocking out AflR significantly reduced dothistromin production, aiding in the identification of additional genes like NorB.

Conclusions:

• Dothistromin gene regulation in D. septosporum demonstrates coordinated control of dispersed secondary metabolite genes.
• Fragmented gene clusters may facilitate adaptation to new pathogenic lifestyles, as seen with the loss of dothistromin production in Cladosporium fulvum due to pseudogenization.