Extracellular matrix (ECM) acts as a physical scaffold preventing recognition and entry of phyto-pathogens while guard cell perceives and integrates signals metabolically. Wilt disease caused by Fusarium oxysporum is a major impediment for crop productivity. Chitosan and its acetylated form chitin are known MAMPs implicated in plant defense, the precise mechanism of chitosan triggered immunity (CTI) that leads to resistance against pathogens remains unknown. To understand the role of ECM and CTI against wilt disease, examination of stomata, ECM components, ROS, NO, eATP levels was investigated in wilt resistant and susceptible chickpea (Cicer arietinum) genotypes. Multiomics using quantitative ECM proteomics and metabolomics was investigated .
Patho-stress was imposed on untreated and chitosan treated three-week-old chickpea seedlings and tissues were harvested at different post-infection time points. Stomatal mechanics were measured using GFS3000. ECM components were analysed in scanning electron microscopy and raman spectroscopy. Temporal ECM proteome and metabolome was developed using iTRAQ coupled Triple-TOF/MS and GC-MS analyses, respectively. Chitosan-induced immunity related network was built and qRT-PCR analysis was performed to validate omicsdatasets.
Morpho-histological examination revealed stomatal closure, reduced stomatal conductance and transpiration rate in chitosan-treated compared to untreated seedlings upon fusariosis. ECM showed fortification leading to oligosaccharide signalling as documented by increased galactose, pectin and secondary carbohydrates. Multiomics using ECM proteomics and metabolomics identified 325 chitosan-triggered IRPs (CTIRPs), 65 CTIRMs that includes, LYM2, kinases, sugars, organic acids and aminoacids linking ROS production, stomatal movements, root nodule development and architecture. Data provide evidence that ROS, NO and eATP governs CTI. Induction of PR proteins, CAZymes and PAL was observed during CTI.
Chitosan regulate ECM dynamics, stomatal movements and root architecture. ECM signaling and stomatal immunity plays pivotal role in CTI. Multi-omics provides evidence how chitosan imparts immunity against Fusariosis. Increased ROS production, antioxidant enzymes, NO and eATP restrict Fusarium attack.