A leaf yeast supplies the vitamin its microbial partner cannot make
A leaf yeast releases thiamine that helps another microorganism colonize Arabidopsis leaves. A single peer-reviewed study combines a European field survey with genetic and plant experiments to trace the exchange. The yeast also persists better when its partner is present within a wider microbial community. That benefit disappears in a simplified pairing, showing that the surrounding community changes the outcome of this relationship.
Science··Morning
A field survey identified partners for plant experiments
Nutrient sharing helps two microorganisms coexist on leaves in a single peer-reviewed study published on October 5. The field survey covered four European countries. Researchers sampled 15 natural Arabidopsis sites and examined 347 plants. Arabidopsis is the model plant used in the work. Marker genes mapped bacteria, fungi, oomycetes and other eukaryotic microbes. The field associations supplied candidates for controlled experiments; some apparently positive associations instead showed opposite effects in tests involving two partners.[1]
The yeast releases thiamine through a membrane protein
The yeast Dioszegia hungarica supplies thiamine to Albugo laibachii, a plant-dependent oomycete that cannot make the vitamin itself. A particular yeast strain releases it through the membrane transport protein DhPER1, helping Albugo establish itself on leaves. Disrupting expression of that gene removed the colonization-promoting effect; restoring it brought the effect back. Different yeast strains did not provide identical support.[1]
Transferring DhPER1 to another strain did not fully reproduce the outcome, indicating that the required gene is not sufficient by itself. Vitamin supplementation and RNA measurements early in infection supported the nutritional link. Sequence comparisons, nearby structural differences and translation-related features supplied additional evidence for the proposed evolutionary interpretation of this nutrient exchange.[1]
Other microbes change the yeast’s benefit
In controlled plant conditions containing a native microbiome, the presence of Albugo supported the yeast’s persistence over 32 days. The same benefit was absent when only the two partners were present. Competition within the wider community therefore changed the relationship’s outcome. The findings concern selected strains on a model plant; field-scale control of plant disease or gains in crop yield were not demonstrated.[1]
