Drawing up a collaborative contract: Amino acid cross‐feeding between interspecies bacterial pairs

Kelly, Erin; Fischer, Alexandria; Collins, Cynthia H.

doi:10.1002/bit.27837

Cited by 6 publications

(2 citation statements)

References 55 publications

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“…We suspect the difference between these findings may be because they tested a community of transposon insertion mutants in a TnSeq screen, where the presence of other mutants could potentially provide amino acids in trans to auxotrophs. In fact, metabolic exchange, including amino acid cross-feeding among microbes is characteristic and reciprocal in a microbial community [43][44][45]. Our data suggest that the rhizosphere may be limiting in many amino acids, and that by synthesizing certain amino acids, bacteria will alter the rhizosphere pH and affect plant immune homeostasis.…”

Section: Discussionmentioning

confidence: 82%

Amino acid availability determines plant immune homeostasis in the rhizosphere microbiome

Liu

Han

Wilson

et al. 2021

Preprint

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Microbes possess conserved microbe-associated molecular patterns (MAMPs) such as flagellin that are recognized by plant receptors to induce immunity. Despite containing the same MAMPs as pathogens, commensals thrive in the plant rhizosphere microbiome indicating they must suppress or evade host immunity. The beneficial bacteria Pseudomonas capeferrum WCS358 can suppress Arabidopsis root immunity via acidification by secreting gluconic acid. While gluconic acid is sufficient to suppress immunity, we found that it is not necessary in a second beneficial strain Pseudomonas simiae WCS417, which produces more gluconic acid than WCS358. To uncover mechanisms that contribute to the suppression of Arabidopsis immunity, we performed a forward genetic screen in EMS-mutagenized P. simiae WCS417 using a flagellin-inducible CYP71A12 pro:GUS reporter as an Arabidopsis immune readout. We identified a mutant that cannot suppress flagellin-elicited CYP71A12 pro:GUS expression or acidify the rhizosphere. Next generation sequencing revealed a mutation in the catabolic site of an ornithine carbamoyltransferase argF, which is required for arginine biosynthesis. The mutant could be complemented by expression of argF from a plasmid, and a ΔargF mutant could not suppress immunity. Fungal pathogens can use alkalization through production of ammonia and glutamate, the arginine biosynthetic precursors, to promote their own growth and virulence. Therefore, we hypothesized that the biosynthesis of specific amino acids may be necessary to reduce levels of ammonia and glutamate to prevent rhizosphere alkalization and bacterial overgrowth. Genetically blocking arginine, glutamine, or proline biosynthesis, or by adding corresponding exogenous amino acids, resulted in rhizosphere alkalization. Interestingly, exogenous amino acids caused bacterial overgrowth in a gluconic acid-deficient mutants. Our findings show that bacterial amino acid biosynthesis contributes to acidification by preventing accumulation of glutamate precursors and the resulting alkalization. Collectively this work shows that by regulating nutrient availability, plants have the potential to regulate their immune homeostasis in the rhizosphere microbiome.

show abstract

Section: Discussionmentioning

confidence: 82%

Amino acid availability determines plant immune homeostasis in the rhizosphere microbiome

Liu

Han

Wilson

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…We suspect the difference between these findings may be because of a community of transposon insertion mutants in a TnSeq screen, where the presence of other mutants could potentially provide amino acids in trans to auxotrophs. In fact, metabolic exchange, including amino acid cross-feeding among microbes, is characteristic and reciprocal in a microbial community ( 33 – 35 ). Our data suggest that the rhizosphere may be limiting in many amino acids, and that by synthesizing certain amino acids, bacteria will alter the rhizosphere pH and affect plant immune homeostasis.…”

Section: Discussionmentioning

confidence: 99%