The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) and Related Family: Mechanistic Insights in Plant Disease Resistance

Abstract

The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) and related NPR1-like proteins are a functionally similar, yet surprisingly diverse family of transcription co-factors. Initially, NPR1 in Arabidopsis was identified as a positive regulator of systemic acquired resistance (SAR), paralogs NPR3 and NPR4 were later shown to be negative SAR regulators. The mechanisms involved have been the subject of extensive research and debate over the years, during which time a lot has been uncovered. The known roles of this protein family have extended to include influences over a broad range of systems including circadian rhythm, endoplasmic reticulum (ER) resident proteins and the development of lateral organs. Recently, important advances have been made in understanding the regulatory relationship between members of the NPR1-like protein family, providing new insight regarding their interactions, both with each other and other defense-related proteins. Most importantly the influence of salicylic acid (SA) on these interactions has become clearer with NPR1, NPR3, and NPR4 being considered bone fide SA receptors. Additionally, post-translational modification of NPR1 has garnered attention during the past years, adding to the growing regulatory complexity of this protein. Furthermore, growing interest in NPR1 overexpressing crops has provided new insights regarding the role of NPR1 in both biotic and abiotic stresses in several plant species. Given the wealth of information, this review aims to highlight and consolidate the most relevant and influential research in the field to date. In so doing, we attempt to provide insight into the mechanisms and interactions which underly the roles of the NPR1-like proteins in plant disease responses.

Oregano essential oil vapour preventsPlasmopora viticolainfection in grapevine (Vitis Vinifera) by triggering autoimmune metabolic pathways

“…Amongst these latter, several isogenes of Enhanced Disease Susceptibility (EDS1; VIT_17s0000g07400, VIT_17s0000g07420, VIT_17s0000g07370) also known as Nonexpressor of PR Genes 1 (NPR 1 ), or Non-inducible Immunity 1 (NIM1) or Salicylic Acid Insensitive 1 (SAI1) , which is an important redox sensitive transcriptional regulator of SA response and a mediator of SA-JA crosstalk (51). This NPR1 gene is thought to be a central immune regulator for systemic-acquired resistance (SAR) and is considered as crucial for the regulation of Pathogenesis Related ( PR) genes expression (51–53).…”

The elicitor protein BcIEB1 and the derived peptide ieb35 provide long‐term plant protection

“…Surprisingly, the incubation of tobacco seedlings with BcIEB1or ieb35 caused the accumulation of transcripts of the NPR1 gene. The NPR1 protein is a positive regulator of SAR mediated by salicylic acid, through the expression of PR genes (Backer et al , 2019), and also positively regulates its own expression in Arabidopsis thaliana via cyclin‐dependent kinase 8 and WRKY DNA‐binding protein 18 (Chen et al , 2019). It is probable that the increased level of NPR1 transcript in seedlings treated with BcIEB1 or ieb35, and the putative accumulation of the protein in the nuclei of tobacco cells, helps maintain a vigilant status to enable a faster induction of PR genes after any challenge by pathogens.…”

“…These are small proteins with antimicrobial activity categorized into 17 families that play a critical role, among others, in disease resistance (Jain and Khurana, 2018). The expression of some of these PR proteins is controlled by the NONEXPRESSER OF PR GENES 1 ( NPR1 ) gene, a key positive regulator of the plant defence response mediated by salicylic acid (Backer et al , 2019).…”

Ultrahigh-activity immune inducer from Endophytic Fungi induces tobacco resistance to virus by SA pathway and RNA silencing

“…PR-1A and nonexpressor of PR (NPR) are the key factors in the SA pathway, involved in N. benthamiana resistance to viruses [33] or other pathogens, such as phytophthora infestations [34]. WRKYs can bind the promoter region of NPR and have functions in the SA signaling pathway [35][36][37]. The high expression of WRKY40 and WRKY70 in tobacco can increase resistance to pathogens [38]; the overexpression of WRKY70 can enhance the expression of SA-responsive PR genes [39]; SA is increased in Arabidopsis mutants by the positive regulation of WRKY genes, including WRKY51 [40].…”