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Published on: March 9, 2021
Thiamine is a vitamin for plant-pathogenic powdery mildew fungi
Björn Sabelleck1, Matthias Freh1, Meltem Lammertz1
1Unit of Plant Molecular Cell Biology, Institute for Biology I, RWTH Aachen University, Worringerweg 1 52056 Aachen, Germany.
Abstract:
Thiamine (vitamin B1) is an essential micronutrient in all forms of life that serves as a cofactor for several enzymes in primary metabolism. Plant-pathogenic and obligate biotrophic powdery mildew fungi appear to be auxotrophic for the micronutrient, as they have lost the majority of the genes needed for thiamine biosynthesis. Using the barley powdery mildew pathogen, Blumeria hordei, as a study object, we found that (1) asexual conidiospores contain detectable levels of thiamine, (2) the B. hordei THI80 gene encodes a functional thiamine pyrophosphokinase, and (3) B. hordei has a functional DUR31-like thiamine transporter likely localizing to the cell surface. We further demonstrated a requirement of the metabolite for the activity of B. hordei transketolase, an enzyme of central carbon metabolism known to be thiamine-dependent in other organisms. Taken together, our data suggest that thiamine is a vitamin for B. hordei and, thus, likely all powdery mildew fungi.
Insights
Powdery mildew fungi, like Blumeria hordei, cannot produce thiamine (vitamin B1). This study confirms thiamine is essential for these plant pathogens, suggesting it
Area of Science:
- Plant Pathology
- Mycology
- Biochemistry
Background:
- Thiamine (vitamin B1) is vital for all life, acting as a cofactor for key enzymes.
- Obligate biotrophic powdery mildew fungi lack genes for thiamine biosynthesis, suggesting auxotrophy.
Purpose of the Study:
- To investigate thiamine's role in the barley powdery mildew fungus, Blumeria hordei.
- To determine if Blumeria hordei requires thiamine as an essential nutrient.
Main Methods:
- Quantified thiamine levels in B. hordei conidiospores.
- Characterized the B. hordei THI80 gene and its encoded thiamine pyrophosphokinase.
- Identified a functional DUR31-like thiamine transporter in B. hordei.
- Assessed the thiamine-dependence of B. hordei transketolase activity.
Main Results:
- Thiamine is present in B. hordei asexual spores.
- A functional thiamine pyrophosphokinase and a cell surface thiamine transporter were identified in B. hordei.
- Thiamine is required for the activity of B. hordei transketolase, an enzyme in central carbon metabolism.
Conclusions:
- Blumeria hordei requires thiamine, indicating it is auxotrophic for this vitamin.
- Thiamine is likely an essential vitamin for all powdery mildew fungi.
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