GmNAC8 acts as a positive regulator in soybean drought stress

•GmNAC8 can respond to drought stress as well as stress-related hormones and is significantly upregulated under drought and hormone treatments.•Compared with WT plants, GmNAC8 overexpression lines exhibited drought tolerance, whereas GmNAC8 knockout lines were drought-sensitive.•Compared with WT plants, Overexpression of GmNAC8 exhibited significantly higher SOD activity and proline content during drought stress.•GmNAC8 physically interacts with GmDi19-3 in the nucleus, and GmDi19-3 is also a positive regulator in soybean under drought stress. NAC proteins represent one of the largest transcription factor (TF) families involved in the regulation of plant development and the response to abiotic stress. In the present study, we elucidated the detailed role of GmNAC8 in the regulation of drought stress tolerance in soybean. The GmNAC8 protein was localized in the nucleus, and expression of the GmNAC8 gene was significantly induced in response to drought, abscisic acid (ABA), ethylene (ETH) and salicylic acid (SA) treatments. Thus, we generated GmNAC8 overexpression (OE1 and OE2) and GmNAC8 knockout (KO1 and KO2) lines to determine the role of GmNAC8 in drought stress tolerance. Our results revealed that, compared with the wild type (WT) plant, GmNAC8 overexpression and GmNAC8 knockout lines exhibited significantly higher and lower drought tolerance, respectively. Furthermore, the SOD activity and proline content were significantly higher in the GmNAC8 overexpression lines and significantly lower in the GmNAC8 knockout lines than in the WT plants under drought stress. In addition, GmNAC8 protein was found to physically interact with the drought-induced protein GmDi19-3 in the nucleus. Moreover, the GmDi19-3 expression pattern showed the same trend as the GmNAC8 gene did under drought and hormone (ABA, ETH and SA) treatments, and GmDi19-3 overexpression lines (GmDi19-3-OE9, GmDi19-3-OE10 and GmDi19-3-OE31) showed enhanced drought tolerance compared to that of the WT plants. Hence, the above results indicated that GmNAC8 acts as a positive regulator of drought tolerance in soybean and inferred that GmNAC8 probably functions by interacting with another positive regulatory protein, GmDi19-3.