Genome wide analysis of NAC transcription factors and their expression pattern during high temperature and drought stress in groundnut

Abstract

NAC (NAM, ATAF1/2 and CUC2) is a prime plant specific transcription factor, which plays a pivotal role in stress signaling. Excavating a relatively large number of NAC TFs under complex environmental cues and understanding their molecular basis, remains a challenge. The objective of this study was to analyse a total of 76 NAC transcription factors of which 38 were from Arachis duranensis (AdNAC) and Arachis ipaensis (AiNAC) for phylogeny, chromosomal location, conserved motif identification including membrane bound NTLs (NAC trans-membrane like), promoter analysis and expression profiles under high temperature and drought stress. The study led to the identification of eight membrane bound NTLs, such as AdNAC26, AdNAC36, AiNAC16, AiNAC17, AiNAC37, AdNAC14, AiNAC12, and AiNAC29, and revealed that majority of NAC proteins had four NAC domain- containing conserved motifs and were localised at the nucleus. The study also reveals AdNAC21 and AiNAC3 as positive regulators under both stress conditions. Our results provide a basis for selection of promising stress- responsive NAC candidates for further functional analysis, leading to development of transgenics with improved productivity of groundnut varieties under drought and high temperature.

Keywords: Conserved motifs, NTL, phylogenetic tree, RT- qPCR