Insight into the Plant Stress Adaptation Strategies during Tripartite Interaction of Plant-Pathogen and Nanoparticles Using Comparative Proteomics Approach

Biosynthesized silver nanoparticles have emerged as an economical approach to combat pathogenic microbes but still remain in nascent stage in field of agriculture. The plants responses during tripartite interaction of plant pathogen and nanoparticles also remain largely unknown. This study demonstrates the use of biosynthesized silver nanoparticles (Spherical, 2-5nm) in combating black spot disease in model plant pathosystem of Arabidopsis thaliana and Alternaria brassicicola. The particles reduced disease severity by 70-80% at a low concentration of 5µg/ml without showing pytotoxicity. It also elicited plant immunity as evident by significant reduction in reactive oxygen species, lipid peroxidation, proline content and consequently decrease in stress enzymes viz. superoxide dismutase, catalase, guaiacol peroxidase, polyphenol oxidase and phenylalanine ammonia lyase. Further, mass spectrometry based comparative proteomics approach was carried out to gain an insight into the protein dynamics during the interaction. After two dimensional gel electrophoresis, a total of 599 proteins expressed during the interaction, in which 144 were found to be differential. 117 differential proteins were identified with significant scores. Out of 117 significant proteins with differential expression, 44% were involved in bioenergy and metabolism (BEM), 20% were in plant defence related proteins, 14, 10 and 12% were involved in cell signalling, storage and biogenesis, and miscellaneous functions respectively. It was observed that expression level of protein involved in protein biogenesis were enhanced to produce abundant antimicrobial metabolites and proteins involved in early stage of plant defence so that production of ROS is minimized, and thus the proteins of late defence were downregulated. Biosynthesized silver nanoparticles performed dual functions to combat the pathogen attack by killing plant pathogen and eliciting plant immunity by altering plant proteome.