Tomato atypical receptor kinase 1 protein abundance is differentially regulated during pathogen infection.
A. GUZMAN (1), D. Lanver (2), K. Taylor (1), J. Kim (1), H. Liu (3), M. Mudgett (1) (1) Stanford University, U.S.A.; (2) Max-Planck-Institut für terrestrische Mikrobiologie, Germany; (3) Department of Plant Pathology, Nanjing Agricultural University, China

Tomato atypical receptor kinase 1 (TARK1) encodes a plasma membrane (PM) protein with five extracellular leucine repeats and a non-RD kinase domain. TARK1-silenced tomato plants are more susceptible to Xanthomonas euvesicatoria (Xcv) strains lacking the bacterial effector XopN or a functional type III secretion (T3S) system, linking TARK1 with PAMP-triggered immunity (PTI). Given that TARK1 has a short extracellular domain and no detectable kinase activity, we hypothesize that it may interact with pattern recognition receptors (PRRs) or other membrane associated components to regulate defense signal signaling. To isolate and characterize TARK1-associated immune complexes, we generated TARK1-HA overexpression lines in tomato. Surprisingly, TARK1 protein did not accumulate significantly in uninfected leaves despite high levels of TARK1 mRNA detected. TARK1 protein however accumulated in response to wounding, PAMPs, defense hormones, and the T3S deficient mutant, Xcv ?hrcV, but was reduced during Xcv infection. High levels of TARK1 correlated with reduced Xcv growth suggesting that TARK1 abundance at the PM contributes to the magnitude of PTI signaling during infection. These data also indicate that one or more Xcv T3S effectors destabilize TARK1 at the PM. Recent progress in the isolation and characterization of TARK1-associated immune complexes required for Xcv immunity will be discussed.

Abstract Number: P17-530
Session Type: Poster