GENOME-WIDE STUDY AND EXPRESSION ANALYSIS OF NODULE-INCEPTION-LIKE PROTEIN (NLP) GENE FAMILY IN PHYSCOMITRELLA PATENS REVEALS ITS ROLE IN NITROGEN RESPONSE

NODULE-INCEPTION- LIKE Proteins (NLPs) are plant specific transcription factors that play a significant role in orchestrating nitrogen response. NLPs have been widely studied in vascular plants but they are not explicitly reported in non-vascular bryophytes till date. In the current study, in silico tools were employed for identification and characterization of NLPs in model bryophyte Physcomitrella patens. Furthermore, the expression profiles of PpNLPs were assessed under variable supply of nitrogen. A total of 6 Physcomitrella patens NLP genes ( PpNLPs) were identified that shared resemblance in their physical and chemical attributes with Arabidopsis thaliana NLPs (AtNLPs). PpNLP genes possessed resemblances in their iso-electric point and hydropathicity values with those of AtNLPs while gene lengths, protein lengths, and molecular weights were found higher in PpNLPs. The online tools suggested that all PpNLPs, except PpNLP6, yield acidic hydrophilic proteins localized in the nucleus and share a significant degree of homology in their gene structures and protein motifs with AtNLPs. Phylogenetic analysis indicated that PpNLPs possess significant evolutionary linkage with Arabidopsis thaliana, Oryza sativa, and Zea mays. Protein-protein interaction analysis suggested that PpNLPs possess substantial coordination with nitrogen responsive genes like nitrate reductase. Expressions of all PpNLPs were up-regulated in the availability of nitrogen (5 and 10 mM) while no significant increment was observed in the absence (0 mM) of nitrogen. The expression levels increased with increasing time treatment of 0, 6, 12, 24, 48, and 72 hours. Results proposed that NLPs are responsive to as well as significantly regulated by nitrogen supply.