PeSNAC-1, a NAC transcription factor from moso bamboo (Phyllostachys edulis) confers tolerance to salinity and drought stress in transgenic rice

NAC (NAM, AFAT, and CUC) proteins play necessary roles in plant response to environmental stresses. However, the functional roles of NAC genes in moso bamboo (Phyllostachys edulis), an essential economic perennial woody bamboo species, are not well documented. In this study, we retrieved 152 PeNAC genes from the moso bamboo V2 genome, and PeSNAC-1 was isolated and functionally characterized. PeSNAC-1 was localized in the nucleus and had no transactivation activity in yeast. PeSNAC-1 extremely expressed in rhizome and young roots (0.1 and 0.5 cm) and was significantly induced by drought and salt treatments but repressed by abscisic acid (ABA), methyl jasmonate (MeJA) and high temperature (42°C) in moso bamboo. Under water shortage and salinity conditions, survival ratios, Fv/Fm values, physiological indexes such as activities of superoxide dismutase, peroxidase, and catalase and contents of malondialdehyde, H2O2, and proline were significantly higher in transgenic rice than the wild type, which suggests enhanced tolerance to drought and salt stress in PeSANC-1 overexpressed plants. Transcript levels of Na+/H+ antiporter and Na+ transporter genes (OsSOS1, OsNHX1 and OsHKT1;5), ABA signaling and biosynthesis genes (OsABI2, OsRAB16, OsPP2C68, OsLEA3-1, OsLEA3, OsNCED3, OsNCED4 and OsNCED5) and ABA independent genes (OsDREB1A, OsDREB1B and OsDREB2A) were substantially higher in transgenic as compared to the wild type. Moreover, protein interaction analysis revealed that PeSNAC-1 could interact with stress responsive PeSNAC-2/4 and PeNAP-1/4/5 in both yeast and plant cells, which indicates a synergistic effect of those proteins in regulating the moso bamboo stress response. Our data demonstrate that PeSNAC-1 likely improved salt and drought stress tolerance via modulating gene regulation in both ABA dependent and independent signaling pathways in transgenic rice. In addition, PeSNAC-1 functions as an important positive stress regulator in moso bamboo, participating in PeSNAC-1 and PeSNAC-2/-4 or PeSNAC-1 and PeNAP-1/4/5 interaction networks.

Keywords: PeSNAC-1; NAC transcription factor; abscisic acid (ABA); moso bamboo; salt and drought stress tolerance.