Corn Smut Fungus Uses Multiple Pathways to Metabolize Sucrose, Switching Strategies Based on Growth Stage
Researchers studying the corn smut fungus Ustilago maydis discovered that the pathogen uses different metabolic pathways to acquire sucrose depending on whether it is growing as yeast or during infection. The fungus employs a non-canonical pathway involving maltose transporters during yeast-like growth, but switches to a canonical sucrose utilization pathway during pathogenic development. This metabolic flexibility may be a common adaptive strategy among pathogenic fungi.
A new study published on bioRxiv reveals that Ustilago maydis, a fungus that causes corn smut disease, possesses unexpected complexity in how it metabolizes sucrose, the primary transport sugar in plants. Researchers found that the fungus encodes a secreted invertase enzyme (Suc2) with a dimeric structure, which differs from previously characterized versions in other fungi. Surprisingly, deletion of genes for the canonical sucrose utilization pathway—including the invertase Suc2, transporter Srt1, and hydrolase Suc1—did not prevent yeast-like growth on sucrose. Instead, the fungus relies on an alternative pathway using a maltose transporter (Agt1) and intracellular maltases during this growth stage. However, during pathogenic development and infection, the fungus switches to the canonical pathway mediated by Srt1 and Agt1. This lifestyle-dependent metabolic switch suggests that flexible carbon acquisition strategies may be widespread among basidiomycete pathogenic fungi.
What's missing
The study does not discuss potential implications for developing fungicides or disease management strategies targeting sucrose metabolism, nor does it address whether this metabolic flexibility exists in other corn pathogens or how it compares quantitatively to sucrose utilization efficiency in related fungi.
What different sources said
- bioRxivCenter
Disentangling the sucrose metabolism of the corn smut Ustilago maydis reveals unexpected complexity
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