Investigating some antioxidant enzymes activity and changing the expression of some defense chitinase genes of potato (Solanum tuberosum L.) after inoculation with chitin

Plant diseases, particularly diseases caused by fungi and oomycetes pose significant challenges in modern agriculture worldwide. Pathogen associated molecular pattern (PAMP) like chitin found in the cell walls of fungi and oomycetes, trigger defence signalling, leading to expression of R-genes and the production of reactive oxygen species (ROS), and accumulation of a wide range of metabolites. Chitin elicitors prompt the expression of defence-related genes such as chitinases, ultimately the resulting in the breakdown of chitin in the pathogen's cell wall. To assess the expression level of certain chitinases in potatoes and the activity of antioxidant enzymes, leaves of a tolerant potato genotype (jelly) was challenged with chitin oligomers in vitro. Result of this study revealed that 48 hours post chitin induction, the expression of different classes of chitinase genes were significantly increased. Class I chitinase (Soltu.DM.10G017450) and class III chitinase (Soltu.DM.11G026160) genes, had respectively the highest (5.5-fold relative to control) and the lowest (1.1-fold relative to control) expression level after 48 hours post chitin inoculation. However, the activities of antioxidant enzymes catalase and ascorbate peroxidase did not change significantly compared to the control. These findings suggest that the application of chitin does not activate the signaling pathways involved in the biosynthesis of antioxidant enzymes 48 hours after chitin treatment. In addition, results of this study may imply that chitinase genes can be cloned by genetic engineering approaches to generate transgenic plants resistant to pathogens.