Comprehensive and evolutionary analysis of Spodoptera litura-inducible Cytochrome P450 monooxygenase gene family in Glycine max elucidate their role in defense

Abstract

Plants being sessile organisms and lacking both circulating phagocytic cells and somatic adaptive immune response, have thrived on various defense mechanisms to fend off insect pests and invasion of pathogens. CYP450s are the versatile enzymes, which thwart plants against insect pests by ubiquitous biosynthesis of phytohormones, antioxidants, and secondary metabolites, utilizing them as feeding deterrents and direct toxins. Therefore, a comprehensive analysis of biotic stress-responsive CYPs from <i>Glycine max</i> was performed to ascertain their function against <i>S. litura</i>-infestation. Phylogenetic analysis and evolutionary studies on conserved domains and motifs disclosed the evolutionary correspondence of these <i>GmCYPs</i> with already characterized members of the CYP450 superfamily and close relatedness to <i>Medicago truncatula.</i> These <i>GmCYPs</i> were mapped on 13 chromosomes; they possess 1-8 exons; they have evolved due to duplication and are localized in endoplasmic reticulumn. Further, identification of methyl-jasmonate, salicylic acid, defense responsive and flavonoid biosynthesis regulating <i>cis</i>-acting elements, their interaction with biotic stress regulating proteins and their differential expression in diverse types of tissues, and during herbivory, depicted their responsiveness to biotic stress. Three-dimensional homology modelling of <i>GmCYPs</i>, docking with heme cofactor required for their catalytic activity and enzyme-substrate interactions were performed to understand the functional mechanism of their action. Moreover, to gain insight into their involvement in plant defense, gene expression analysis was evaluated, which revealed differential expression of 11 <i>GmCYPs</i> upon <i>S. litura</i>-infestation, 12 <i>GmCYPs</i> on wounding while foliar spray of ethylene, methyl-jasmonate and salicylic acid differentially regulated 11 <i>GmCYPs</i>, 6 <i>GmCYPs</i>, and 10 <i>GmCYPs</i> respectively. Our study comprehensively analysed the underlying mechanism of <i>GmCYPs</i> function during <i>S. litura</i>-infestation, which can be further utilized for functional characterization to develop new strategies for enhancing soybean resistance to insect pests.