COI1 dependent jasmonic acid signalling positively modulates ROS scavenging system in transgenic hairy root culture of tomato

Abstract

Reactive oxygen species (ROS) production is a routine event in plants. ROS function as signalling molecules in regulating plant development and defence. However, their accumulation beyond threshold leads to toxicity. Hence, plants are evolved with specialized ROS scavenging system involving phytohormones (synthesis and signalling), enzymes and metabolites. To understand the role of phytohormone jasmonic acid (JA) signalling in ROS scavenging, tomato coronatine insensitive 1 (SlCOI1), a key gene in JA signalling, was silenced and overexpressed in tomato transgenic hairy roots (HR) under the constitutive promoter. Targeted metabolomics of transgenic HR revealed accumulation of phenolic acids including ferulic acid, coumaric acid, vanillic acid, and flavonoid catechin in SlCOI1 overexpressed line. Moreover, osmolyte amino acids proline, asparagine, and glutamine showed a positive co-relation with transgenic overexpression of SlCOI1. Ascorbic acid-glutathione, a crucial antioxidant system was found to be influenced by COI1-mediated JA signalling. The expression of genes encoding enzymes superoxide dismutase 1, ascorbate peroxidase 1, and dehydroascorbate reductase 2 was found to be down and upregulated in SlCOI1 silenced and overexpressed lines, respectively. Methyl jasmonate and Fusarium oxysporum f.sp. lycopersici crude extract treatment further confirmed the regulatory role of COI1-mediated JA signalling in regulation of enzymatic components involved in ROS scavenging. The COI1-mediated JA signalling could also elevate the expression of RESPIRATORY BURST OXIDASE HOMOLOG-B gene which is involved in ROS wave signal generation. The present study underscores the role of COI1-mediated JA signalling in modulating enzymatic and non-enzymatic components of ROS scavenging system and pathogen associated molecular pattern triggered immunity.