AAL-toxin induced stress in Arabidopsis thaliana is alleviated through GSH-mediated salicylic acid and ethylene pathways

AAL toxin, the major virulence factor of Alternaria alternata f. sp. lycopersici, is recognized to cause necrotic cell death in plants. Glutathione (GSH) is a noteworthy participant in plant defence. However, how GSH is involved in regulating the AAL treated cell death is yet to be explored. Here, Arabidopsis thaliana Col-0, and previously developed transgenic line AtECS1, were exogenously treated with AAL toxin and a proteomic profile (ProteomeXchange accession: PXD017124) was obtained by nano LC–MS/MS analysis. Few salicylic acid (SA) and ethylene (ET) responsive proteins, along with others were identified. Selected SA-responsive genes were noted to be up regulated in AAL treated AtECS1 compared to Col-0 by quantitative real time-PCR (qRT-PCR), beside the up regulation of ascorbate peroxidase 1 (APX1) and chaperone like heat shock protein (HSP), together with myrosinase. Interestingly, ET biosynthetic and signaling marker genes were down regulated in AAL treated AtECS1 compared to Col-0. Augmentation of SA content and proteins regulated by it, while, reduction of endogenous 1-aminocyclopropane-1-carboxylate (ACC) content and ET-related proteins was significant in AAL treated AtECS1 compared to Col-0. Collectively, these findings suggested that under necrotrophic attack as mimicked here by AAL treatment, GSH may be involved in resistance primarily by SA-mediated ET suppression in addition to various stress responsive molecules.