Unravelling the outcome of calcium nitrate and organic amendments on nitrogen fixation and flavonoids in Arachis hypogaea

Abstract

Nod inducing gene (NIG) families plays a crucial role in several stages of biological nitrogen fixation which includes flavonoids exudation from roots and perception on rhizobacteria, phosphorylation cascade of protein kinases, node genes expression in rhizobacteria, node proteins causing root hair curling and nodule formation. Nod inducing genes characterization has not been performed in Arachis hypogaea except for some nodulation inducing genes in other legumes. In this study, we performed a genome-wide analysis of NIG family in Arachis hypogaea followed by phylogenetic clustering analysis, gene structure determination, detection of conserved motifs, subcellular localization, conserved motifs, cis-acting elements and promoter region analysis. Based on homology study total of 15 Nod inducing genes were identified and characterization of the genes reveals the structural and functional similarity with the difference in amino acids at few positions. Invitro studies were conducted on the golden variety of peanut to identify the effects of nitrogen fertilizer (calcium nitrate) on flavonoid exudation and biological nitrogen fixation. The experimental design consisted of four different treatments (T1=soil control, T2=Ca(NO3)2, T3 = biochar, T4=Biochar+ Ca(NO3)2 ). Phenotypic and chlorophyll analysis suggested that the use of calcium nitrate fertilizer has no growth benefits to the plant. This study not only not only provides identification and characterization of genes underlying developmental and functional stages of nodulation and biological nitrogen fixation but also lays the foundation for further revelation of Nod inducing gene family. In addition, this study also helps to make a potent nitrogen fertilizer that is not only environmentally friendly but also provides high yields of plants.