Salt stress is an adverse environmental factor for plant growth and development. Under salt stress, plants can activate the selective autophagy pathway to alleviate stress. However, the regulatory mechanism of selective autophagy in response to salt stress remains largely unclear. Here, we report that the selective autophagy receptor PagNBR1 (neighbor of BRCA1) is induced by salt stress in Populus. Overexpression of PagNBR1 in poplar enhanced salt stress tolerance. Compared with wild type (WT) plants, the transgenic lines exhibited higher antioxidant enzyme activity, less reactive oxygen species (ROS), and higher net photosynthesis rates under salt stress. Furthermore, co-localization and yeast two-hybrid analysis revealed that PagNBR1 was localized in the autophagosome and could interact with ATG8 (autophagy-related gene). PagNBR1 transgenic poplars formed more autophagosomes and exhibited higher expression of ATG8, resulting in less accumulation of insoluble protein and insoluble ubiquitinated protein compared to WT under salt stress. The accumulation of insoluble protein and insoluble ubiquitinated protein was similar under the treatment of ConA in WT and transgenic lines. In summary, our results imply that PagNBR1 is an important selective autophagy receptor in poplar and confers salt tolerance by accelerating antioxidant system activity and autophagy activity. Moreover, the NBR1 gene is an important potential molecular target for improving stress resistance in trees.

盐胁迫是植物生长发育的不利环境因素。在盐胁迫下，植物可以激活选择性自噬途径来缓解胁迫。但是，选择性自噬响应盐胁迫的调节机制仍不清楚。在这里，我们报道了选择性自噬受体PagNBR1（BRCA1的邻居）是由盐胁迫引起的 胡杨。杨树中PagNBR1的过表达增强了盐胁迫的耐受性。与野生型（WT）植物相比，转基因品系在盐胁迫下表现出更高的抗氧化酶活性，更少的活性氧（ROS）和更高的净光合作用率。此外，共定位和酵母双杂交分析表明PagNBR1 被定位在自噬体中并且可以与ATG8（自噬相关基因）相互作用。 PagNBR1 转基因杨形成更多的自噬体，并表现出较高的表达。 ATG8，与野生型相比，在盐胁迫下，不溶蛋白和不溶泛素化蛋白的积累更少。在野生型和转基因株系中，在ConA处理下，不溶蛋白和不溶泛素化蛋白的积累相似。总而言之，我们的结果暗示PagNBR1是杨树中重要的选择性自噬受体，通过加速抗氧化系统活性和自噬活性赋予耐盐性。而且，丁腈橡胶1 基因是提高树木抗逆性的重要潜在分子靶标。