Biology subjects

Agorsor, I. D. K.

Publications and source records attributed to Agorsor, I. D. K..

2 recordsLinked to original sources

bioRxiv2025

The Arabidopsis UMAMIT30 transporter contributes to amino acid root exudation

ABSTRACTO_ST_ABSBackgroundC_ST_ABSRoot exudation is an important trait that enables plants to shape their interactions with soil-borne organisms. Amino acids present in root exudates play important roles in bacterial chemotaxis, bacterial metabolism, and root colonization, contributing to plant nutrition and health. Notwithstanding the importance of amino acids in shaping the rhizosphere microbiome, the identities of the plant amino acid transporters that mediate their root exudation have remained elusive. ResultsHere, we report that the Arabidopsis UMAMIT30 transporter, robustly expressed in root and shoot tissues, significantly contributes to amino acid root exudation. umamit30 loss-of-function mutants were compromised for amino acid root exudation as shown by the low concentration of amino acids, particularly glutamine, recovered from root exudates compared to wild-type plants. Amino acid quantification, as well as uptake and secretion assessments using radiolabelled glutamine, revealed that the shoots of umamit30 accumulate amino acids and have a reduced capacity to secrete glutamine, impacting root exudation. ConclusionsOur results identify UMAMIT30 as a broadly specific amino acid exporter strongly expressed in Arabidopsis vasculature. Loss-of-function mutants displayed reduced amino acid levels in root exudates, with significant drops in glutamine and asparagine among others, yet exhibited no detectable growth defects. UMAMIT30 disruption led to elevated shoot amino acid content and reduced glutamine efflux from shoots, suggesting a role in phloem uploading rather than root exudation alone. Despite decreased levels of root exuded amino acids, beneficial Pseudomonas interactions and plant-growth-promotion remained unaffected.

plant biology↗

bioRxiv2022

The LHT1 amino acid transporter limits Pseudomonas simiae growth in the rhizosphere, an essential function for bacteria-mediated plant growth promotion

The root microbiome structure ensures optimal plant-host health and fitness, and it is, at least in part, defined by the plant genotype. It is well-documented that root-secreted amino acids promote microbial chemotaxis and growth in the rhizosphere. However, whether the plant-mediated re-uptake of amino acids contributes to maintaining optimal levels of amino acids in the root exudates, and in turn, microbial growth and metabolism, remains to be established. Here we show that LHT1, an amino acid inward transporter expressed in Arabidopsis thaliana roots, limits the growth of the plant-growth-promoting bacteria Pseudomonas simiae WCS417r (Ps WCS417r). Amino acid profiling of the lht1 mutant root exudates showed increased levels of glutamine, among other amino acids. Interestingly, lht1 exudates or Gln-supplemented wild-type exudates enhance Ps WCS417r growth. However, despite promoting bacterial growth and robust root colonization, lht1 exudates and Gln-supplemented wild-type exudates inhibited plant growth in a Ps WCS417r-dependent manner. Transcriptional analysis of defense and growth marker genes revealed that plant growth inhibition was not linked to the elicitation of plant defense, but likely to the impact of Ps WCS417r amino acids metabolism on auxin signaling. These data suggest that an excess of amino acids in the rhizosphere impacts Ps WCS417r metabolism which in turn inhibits plant growth. Together, these results unveil that LHT1 regulates the amino acid-mediated interaction between plants and Ps WCS417r and suggest a complex relationship between root-exuded amino acids, root colonization by beneficial bacteria, bacterial metabolism, and plant growth promotion.

plant biology↗