BpNAC012 Positively Regulates Abiotic Stress Responses and Secondary Wall Biosynthesis

• Published in: Plant physiology (Bethesda) Vol. 179; no. 2; pp. 700 - 717
• Main Authors: Hu, Ping, Zhang, Kaimin, Yang, Chuanping
• Format: Journal Article
• Language: English
• Published: United States 01-02-2019
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.18.01167

NAC (NAM, ATAF1/2, and CUC2) transcription factors play important roles in plant biological processes and stress responses. Here, we characterized the functional roles of BpNAC012 in white birch (
). We found that BpNAC012 serves as a transcriptional activator. Gain- and loss-of-function analyses revealed that the transcript level of
was positively associated with salt and osmotic stress tolerance. BpNAC012 activated the core sequence CGT[G/A] to induce the expression of abiotic stress-responsive downstream genes, including Δ-1-pyrroline-5-carboxylate synthetase, superoxide dismutase, and peroxidase, resulting in enhanced salt and osmotic stress tolerance in
overexpression transgenic birch lines. We also showed that
is expressed predominantly in mature stems and that RNA interference-induced suppression of
caused a drastic reduction in the secondary wall thickening of stem fibers. Overexpression of
activated the expression of secondary wall-associated downstream genes by directly binding to the secondary wall NAC-binding element sites, resulting in ectopic secondary wall deposition in the stem epidermis. Moreover, salt and osmotic stresses elicited higher expression levels of lignin biosynthetic genes and elevated lignin accumulation in
overexpression lines. These findings provide insight into the functions of NAC transcription factors.