MAMP-elicited changes in amino acid transport activity contribute to restricting bacterial growth.

XIAOMU ZHANG; PRAMOD KHADKA; PATRYK PUCHALSKI; JOSS D. LEEHAN; FRANCO R. ROSSI; SAKIKO OKUMOTO; GUILLAUME PILOT; CRISTIAN H. DANNA

PLANT PHYSIOLOGY.

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2022

0032-0889

Plants live under the constant challenge of microbes that probe the environment in search of potential hosts. Plant cells perceive Microbe-Associated Molecular Patterns (MAMPs) from incoming microbes and activate defense responses that suppress attempted infections. Despite significant progress in understanding MAMP-triggered signaling pathways, the downstream mechanisms that suppress bacterial growth and disease remain poorly understood. Here we uncover that MAMP-perception in Arabidopsis elicits dynamic changes in extracellular concentrations of free L-amino acids (AA). Within the first three hours of MAMP perception, a fast and transient inhibition of AA uptake produces a transient increase in extracellular AA concentrations. Within four and twelve hours of MAMP perception, a sustained enhanced uptake activity decreases the extracellular concentrations of AA. Gene expression analysis showed that salicylic acid (SA)-mediated signaling contributes to inducing the expression of AA/H+ symporters responsible for the MAMP-induced enhanced uptake. A screening of loss-of-function mutants identified the AA/H+ symporter Lysin/Histidine Transporter-1 (LHT1) as a significant contributor to MAMP-induced enhanced uptake of AA. Infection assays in lht1-1seedlings revealed that high concentrations of extracellular AA promote bacterial growth in the absence of induced defense elicitation but contribute to suppressing bacterial growth upon MAMPs perception. Overall, the data presented in this study uncovered a mechanistic connection between MAMP-induced plant defense and suppression of bacterial growth through the modulation of AA transport activity.