Elucidating the Effects of Organic Amendment and Nitrogen Source on Flavonoids and Nitrogen Fixation in Arachis Hypogaea

Abstract

Biological nitrogen fixation plays a crucial role in the fixation of atmospheric nitrogen. Process of BNF involves flavonoids exudation from the root of leguminous plants, perception of flavonoids on receptors of plant growth-promoting rhizobia, entry of rhizobia in the roots, formation of infectious thread, nod genes induction, and nodules organogenesis in roots. Nodules are the sites for the fixation of atmospheric nitrogen. Identification and characterization of genes in the process of nodulation have not been achieved in the past. In this study, genome-wide analysis of genes involved in the nodulation process has been performed which consists of phylogenetic analysis, conserved motif analysis, gene structure prediction, conserved domain identification, subcellular localization, promoter region prediction, and cis-acting element identification. Homology study identified and characterized a total of 15 genes that revealed functional and structure similarity with few amino acid differences at a scarce position. These genes are widely distributed in the genome of Arachis hypogaea on 10 chromosomes among 20 chromosomes. In-vitro experiment on a golden variety of peanut plants identifies the effect of urea fertilizer with and without biochar on biological nitrogen fixation and plant growth and development. Four different treatments (T1 = control, T2 = Urea, T3 = Biochar, T4 = Urea + Biochar) are included in experimental design. Phenotypic analysis revealed that nitrogen fertilizer with and without biochar is not affecting plant growth and development, however, chlorophyll analysis suggested that urea fertilizer is directly proportional to chlorophyll content. Identification and characterization of nodulation genes lay down the foundation for the improvement of the biological nitrogen fixation process in the future. Moreover, it is proven from the experiment that nitrogen fertilizer (urea) usage in a leguminous crop field is a waste of resources which is environmentally friendly results with high