PT  - JOURNAL ARTICLE
AU  - Daniel Gómez-Pérez
AU  - Monja Schmid
AU  - Vasvi Chaudhry
AU  - Ana Velic
AU  - Boris Maček
AU  - Ariane Kemen
AU  - Eric Kemen
TI  - Proteins released into the plant apoplast by the obligate parasitic protist <em>Albugo</em> selectively repress phyllosphere-associated bacteria
AID  - 10.1101/2022.05.16.492175
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.05.16.492175
4099  - http://biorxiv.org/content/early/2022/05/17/2022.05.16.492175.short
4100  - http://biorxiv.org/content/early/2022/05/17/2022.05.16.492175.full
AB  - Biotic and abiotic interactions shape natural microbial communities. The mechanisms behind microbe-microbe interactions, particularly those protein-based, are not well understood. We hypothesize that secreted proteins are a powerful and highly specific toolset to shape and defend plant niches. We have studied Albugo candida, an obligate plant parasite from the protist Oomycota phylum, for its potential to modulate the growth of bacteria through secretion of proteins into the apoplast. Amplicon sequencing and network analysis of Albugo-infected and uninfected samples revealed an abundance of negative correlations between Albugo and other phyllosphere microbes. Analysis of the apoplastic proteome of Albugo colonized leaves combined with machine-learning predictors enabled the selection of candidates for heterologous expression and study of their inhibitory activity. We found that three of the candidate proteins show selective antimicrobial activity on gram-positive bacteria isolated from Arabidopsis thaliana and that these inhibited bacteria are important for the stability of the community structure. We could ascribe the antibacterial activity of the candidates to intrinsically disordered regions and positively correlate it with net charge. This is the first report of protist proteins with antimicrobial activity under apoplastic conditions that therefore are potential biocontrol tools for targeted manipulations of the microbiome.Competing Interest StatementThe authors have declared no competing interest.