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.

中文翻译：

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GmNAC8 在大豆干旱胁迫中起正调节作用

NAC 蛋白代表了最大的转录因子 (TF) 家族之一，涉及植物发育的调节和对非生物胁迫的响应。在本研究中，我们阐明了 GmNAC8 在调节大豆干旱胁迫耐受性中的详细作用。GmNAC8 蛋白定位于细胞核中，响应干旱、脱落酸 (ABA)、乙烯 (ETH) 和水杨酸 (SA) 处理显着诱导 GmNAC8 基因的表达。因此，我们产生了 GmNAC8 过表达（OE1 和 OE2）和 GmNAC8 敲除（KO1 和 KO2）系，以确定 GmNAC8 在干旱胁迫耐受性中的作用。我们的结果表明，与野生型 (WT) 植物相比，GmNAC8 过表达和 GmNAC8 敲除系分别表现出显着更高和更低的耐旱性。此外，在干旱胁迫下，GmNAC8 过表达株系的 SOD 活性和脯氨酸含量显着高于 GmNAC8 基因敲除株系，而 GmNAC8 基因敲除株系的 SOD 活性和脯氨酸含量显着低于 WT 植物。此外，还发现 GmNAC8 蛋白与细胞核中的干旱诱导蛋白 GmDi19-3 发生物理相互作用。此外，GmDi19-3 表达模式与 GmNAC8 基因在干旱和激素（ABA、ETH 和 SA）处理下以及 GmDi19-3 过表达系（GmDi19-3-OE9、GmDi19-3-OE10 和 GmDi19 -3-OE31) 显示出与 WT 植物相比增强的耐旱性。因此，上述结果表明 GmNAC8 作为大豆耐旱性的正调节因子，并推断 GmNAC8 可能通过与另一种正调节蛋白 GmDi19-3 相互作用而发挥作用。