MAMP-elicited changes in amino acid transport activity contribute to restricting bacterial growth.
Zhang, X., Khadka, P., Puchalski, P., Leehan, J. D., Rossi, F. R., Okumoto, S., Pilot, G. and Danna, C. H.
Department of Biology, University of Virginia, Charlottesville, VA 22904, USA.
Instituto Tecnologico Chascomus (INTECH), Universidad Nacional de General San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET). Chascomus, Buenos Aires 7130, Argentina.
School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
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 the substantial progress made in understanding MAMP-triggered signaling pathways, the downstream mechanisms that suppress bacterial growth and disease remain poorly understood. Here, we uncover how MAMP perception in Arabidopsis (Arabidopsis thaliana) elicits dynamic changes in extracellular concentrations of free L-amino acids (AAs). Within the first 3 hours of MAMP perception, a fast and transient inhibition of AA uptake produces a transient increase in extracellular AA concentrations. Within 4 and 12 hours of MAMP perception, a sustained enhanced uptake activity decreases the extracellular concentrations of AAs. 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 an important contributor to MAMP-induced enhanced uptake of AA. Infection assays in lht1-1 seedlings revealed that high concentrations of extracellular AA promote bacterial growth in the absence of induced defense elicitation but contribute to suppressing bacterial growth upon MAMP perception. Overall, the data presented in this study reveal a mechanistic connection between MAMP-induced plant defense and suppression of bacterial growth through the modulation of AA transport activity.
Plant Physiology : (2022)