Identification of a Protein that Interacts with LeATL6 Ubiquitin-protein Ligase E3 Upregulated in Tomato Treated with Elicitin-Like Cell Wall Proteins ofPythium oligandrum

Abstract

The expression of LeATL6, which encodes RING-H2 zinc finger ubiquitin-protein ligase E3, is highly induced in tomato roots treated with the elicitin-like cell wall protein fraction (CWP) from the non-pathogenic oomycete Pythium oligandrum, which enhances resistance to pathogens through a jasmonic acid (JA)-dependent signalling pathway. In this study, the role of LeATL6 for CWP-induced defence response was further analysed. To screen the putative target protein of LeATL6 for the CWP-induced defence mechanism in tomato, we used a yeast two-hybrid system to screen five clones encoding a protein that interacts with LeATL6. Four clones had a function associated with the ubiquitin-proteasome system. Another positive clone encoded a protein sharing homology with S-adenosylmethionine decarboxylase (SAMDC). In CWP-treated tomato roots, SAMDC activity was clearly suppressed. Thus, the interaction of SAMDC with LeATL6 and the decreased SAMDC activity may be associated with JA-dependent induced resistance in tomato treated with P. oligandrum.