Thiamine cross-feeding drives microbial coexistence in the leaf microbiome.

Thiamine cross-feeding between Dioszegia hungarica and Albugo laibachii promotes their coexistence in the leaf microbiome.

• Why it matters: Understanding microbial community stability is vital for host health and ecosystem function, but the molecular mechanisms behind community assembly remain unclear.
• What they did: A continental-scale microbiome survey identified an asymmetric mutualism where Dioszegia supplies thiamine to Albugo, with genomic and transcriptomic analyses showing natural selection on thiamine production; in planta assays confirmed mutual support.
• The result: This metabolic cross-feeding mediates microbial coexistence and microbiome stability, suggesting that targeting nutrient flows could help engineer microbiomes and improve plant resilience.