Alkyl Gallates Display Elicitor Activities In Tobacco Plants

Abstract

Alkyl gallates showed elicitor activities on tobacco in both whole plants and cell suspensions. Methyl gallate (MG), ethyl gallate (EG) and n-propyl gallate (PG) infiltration into tobacco leaves induced hypersensitive reaction-like lesions and topical production of autofluorescent compounds revealed under UV light. When sprayed on tobacco plants at 5 mM, EG promoted upregulation of defence-related genes such as the antimicrobial PR1, {beta}-1,3-glucanase PR2, chitinase PR3 and osmotin PR5 target genes. Tobacco BY-2 cells challenged with EG underwent cell death in 48 h, significantly reduced in the presence of the protease inhibitor aprotinin. The three alkyl gallates all caused alkalinisation of the BY-2 extracellular medium, whereas gallic acid did not trigger any pH variation. Using EGTA or LaCl3, we showed that Ca2+ mobilisation occurred in BY-2 cells elicited with EG. Overall, our findings are the first evidence of alkyl gallate elicitor properties with early perception events on plasma membrane, potential hypersensitive reactions and PR-related downstream defence responses in tobacco.\n\nHighlights- Alkyl gallates elicited defence reactions in tobacco\n- Alkyl gallates induced local biochemical changes in tobacco leaves\n- Alkyl gallates caused modification of plasma membrane properties\n- Ethyl gallate led to defence transcript accumulation and dose-dependent cell death associated with hypersensitive response\n- Alkyl gallates are novel elicitor agents well-suited to crop protection schemes.