Regulatory Network Identification, Promoter and Expression Analysis of Arabidopsis thaliana NPR1 in Defense Responses against Stresses

Abstract

Salicylic acid (SA) and jasmonic acid (JA) phytohormones have been known for their roles in plant defense behaviour against biotic and abiotic stresses. They regulate defense pathways by antagonistic interaction. NPR1 as a key regulatory factor in the cross-talk between SA and JA, signaling is essential for the inhibition of JA-responsive gene expression by SA. In silico promoter analysis of 1.5 kb promoter regions of NPR1 gene revealed that NPR1 contains 23 MYB and 20 WRKY transcription factor binding sites. Different cis-elements associated with various stress responses were identified in Arabidopsis thaliana NPR1. The most common element was allocated to the defense responses against biotic stresses. Based on gene network analysis, NPR1, TGA2 and TGA3 were predicted to have functional cooperation with each other. Affymetrix microarray data analysis of A. thaliana under SA treatment demonstrated that most genes involved in NPR1 network are up-regulated under SA treatment. Therefore, interaction and cooperation between these factors might serve to fine-tune regulation of defense and immune responses against biotic and abiotic stresses.

Keywords

• abiotic and biotic stresses
• Arabidopsis thaliana
• gene network
• in silico analysis
• NPR1
• regulatory elements