Functional characterization of NAC55 transcription factor from oilseed rape (Brassica napus L.) as a novel transcriptional activator modulating reactive oxygen species accumulation and cell death

Plant Mol Biol. 2016 Sep;92(1-2):89-104. doi: 10.1007/s11103-016-0502-7. Epub 2016 Jun 16.

Abstract

NAC transcription factors (TFs) are plant-specific and play important roles in development, responses to biotic and abiotic cues and hormone signaling. So far, only a few NAC genes have been reported to regulate cell death. In this study, we identified and characterized a NAC55 gene isolated from oilseed rape (Brassica napus L.). BnaNAC55 responds to multiple stresses, including cold, heat, abscisic acid (ABA), jasmonic acid (JA) and a necrotrophic fungal pathogen Sclerotinia sclerotiorum. BnaNAC55 has transactivation activity and is located in the nucleus. BnaNAC55 is able to form homodimers in planta. Unlike ANAC055, full-length BnaNAC55, but not either the N-terminal NAC domain or C-terminal regulatory domain, induces ROS accumulation and hypersensitive response (HR)-like cell death when expressed both in oilseed rape protoplasts and Nicotiana benthamiana. Furthermore, BnaNAC55 expression causes obvious nuclear DNA fragmentation. Moreover, quantitative reverse transcription PCR (qRT-PCR) analysis identified that the expression levels of multiple genes regulating ROS production and scavenging, defense response as well as senescence are significantly induced. Using a dual luciferase reporter assay, we further confirm that BnaNAC55 could activate the expression of a few ROS and defense-related gene expression. Taken together, our work has identified a novel NAC TF from oilseed rape that modulates ROS accumulation and cell death.

Keywords: Brassica napus; Cell death; NAC; Reactive oxygen species; Stress; Transcription factor.

MeSH terms

  • Brassica napus / genetics
  • Brassica napus / metabolism*
  • Cell Death / genetics
  • Cell Death / physiology
  • Gene Expression Regulation, Plant / genetics
  • Gene Expression Regulation, Plant / physiology
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Reactive Oxygen Species / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Plant Proteins
  • Reactive Oxygen Species
  • Transcription Factors