Oilseed rape NAC56 transcription factor modulates reactive oxygen species accumulation and hypersensitive response‐like cell death

Abstract

The NAC (NAM, ATAF1/2, CUC2) transcription factor gene family is plant-specific and plays diverse roles in development and responses to abiotic stresses and pathogen challenge. Oilseed rape (Brassica napus) or canola is an important oil crop worldwide, however, the function of NAC genes in it remains largely elusive. In the present study, we identified and characterized the NAC56 gene isolated from oilseed rape. Expression of BnaNAC56 was induced by abscisic acid (ABA), jasmonic acid (JA), methyl viologen (MV) and a necrotrophic fungal pathogen Sclerotinia sclerotiorum, but repressed by cold. BnaNAC56 is a transcription activator and localized to nuclei. Overexpression of BnaNAC56 induced reactive oxygen species (ROS) accumulation and hypersensitive response (HR)-like cell death, with various physiological measurements supporting these. Furthermore, BnaNAC56 expression caused evident nuclear DNA fragmentation. Moreover, quantitative reverse transcription PCR (qRT-PCR) analysis identified that the expression levels of multiple genes regulating ROS homeostasis, cell death and defense response were significantly induced. Using a dual luciferase reporter assay, we further confirmed that BnaNAC56 could activate the expression of a few ROS- and cell death-related genes. In summary, our data demonstrate that BnaNAC56 functions as a stress-responsive transcriptional activator and plays a role in modulating ROS accumulation and cell death.

Engineering Multiple Abiotic Stress Tolerance in Canola, Brassica napus

“…BnNAC19 and BnNAC82 have been shown to induce a hypersensitive response and cell death under stress due to ROS accumulation (Wang B. et al, 2015). Independent studies have reported similar observations in tobacco and B. napus protoplasts due to transient expression of BnNAC55, BnNAC56, BnNAC87, and BnNAC103 (Niu et al, 2014;Niu et al, 2016;Chen et al, 2017;Yan et al, 2017). Contrary to this transgenic rice overexpressing SNAC3 showed enhanced tolerance to high temperature, drought, and oxidative stress caused by methyl viologen (MV) due to lower accumulation of ROS (Fang et al, 2015).…”

Stressed to Death: The Role of Transcription Factors in Plant Programmed Cell Death Induced by Abiotic and Biotic Stimuli

“…The transcription of NAC089 is itself promoted by two membrane bound TFs, bZIP28 and bZIP60, highlighting the multiple levels of regulation involved in initiating the PCD cascade ( Yang et al., 2014 ). In rapeseed, four NAC TFs (BnaNAC55, BnaNAC56, BnaNAC87, and BnaNAC103) have separately been shown to be involved in PCD following treatment with diverse abiotic stressors ( Niu et al., 2014 ; Niu et al., 2016 ; Chen et al., 2017 ; Yan et al., 2017 ). In all cases, expression of the respective TF resulted in the development of HR-like lesions, reactive oxygen species (ROS) accumulation, and DNA degradation, however, the molecular mechanisms by which these TFs induce cell death has not been examined.…”

Under fire-simultaneous volatilome and transcriptome analysis unravels fine-scale responses of tansy chemotypes to dual herbivore attack

“…In the transcriptomic analysis, treatment contrast group (a), detailing plants that were treated with aphids in relation to untreated plants, DEGs encoding tansy orthologs of NAC56 transcription factor and a TMV resistance protein N were upregulated. The NAC56 transcription factor (TF) is known to play a role in plant responses to abiotic stress and challenge by pathogens [45]. Chen and colleagues demonstrated that in Brassica napus (oilseed rape), BnNAC56 was significantly induced by JA, SA, and ABA, indicating that it may play a central role in plant tolerance of biotic stresses.…”