Asian Natural Environmental Science Center (ANESC), The University of Tokyo, Nishitokyo-shi, Tokyo, 188-0002, Japan.
Laboratory of Crop Physiology, Research Faculty of Agriculture, Hokkaido University, Sapporo-shi, Hokkaido, Japan.
Plant Physiol Biochem. 2019 Feb;135:546-553. doi: 10.1016/j.plaphy.2018.11.004. Epub 2018 Nov 10.
Pearl millet (Pennisetum glaucum) is the sixth-leading cereal crop and a staple food crop. It is known for its high tolerance to abiotic stress and good nutrient profile. NAC (NAM, ATAF1/2 and CUC) transcription factors (TFs) play an important role in abiotic stress tolerance. In our study, the pearl millet stress-responsive NAC TF gene PgNAC21 was characterized. Gene expression analysis revealed that PgNAC21 expression is induced by salinity stress and abscisic acid (ABA) treatment. In silico promoter analysis showed the presence of ABA response elements (ABREs) and MYB TF binding sites. A yeast one-hybrid assay indicated that a putative MYB TF in pearl millet, PgMYB1, binds to the promoter of PgNAC21. A transactivation assay in yeast cells revealed that PgNAC21 functions as a transcription activator and that its activation domain is located in its C-terminus. Relative to control plants, Arabidopsis plants overexpressing PgNAC21 exhibited better seed germination, heavier fresh weight and greater root length under salinity stress. Overexpression of PgNAC21 in Arabidopsis plants also enhanced the expression of stress-responsive genes such as GSTF6 (GLUTATHIONE S-TRANSFERASE 6), COR47 (COLD-REGULATED 47) and RD20 (RESPONSIVE TO DEHYDRATION 20). Our data demonstrate that PgNAC21 functions as a stress-responsive NAC TF and can be utilized in transgenic approaches for developing salinity stress tolerance in crop plants.
珍珠粟（Pennisetum glaucum）是第六大谷类作物和主食作物。它以对非生物胁迫的高耐受性和良好的营养状况而闻名。NAC（NAM、ATAF1/2 和 CUC）转录因子（TF）在非生物胁迫耐受性中发挥重要作用。在我们的研究中，鉴定了珍珠粟应激响应 NAC TF 基因 PgNAC21。基因表达分析表明，PgNAC21 的表达受盐胁迫和脱落酸（ABA）处理诱导。通过计算机启动子分析表明存在 ABA 反应元件（ABREs）和 MYB TF 结合位点。酵母单杂交试验表明，珍珠粟中的一个假定 MYB TF，PgMYB1，与 PgNAC21 的启动子结合。酵母细胞中的转录激活试验表明，PgNAC21 作为转录激活因子发挥作用，其激活结构域位于其 C 末端。与对照植物相比，过表达 PgNAC21 的拟南芥植物在盐胁迫下表现出更好的种子萌发、更重的鲜重和更长的根。在拟南芥植物中过表达 PgNAC21 还增强了应激响应基因如 GSTF6（GLUTATHIONE S-TRANSFERASE 6）、COR47（COLD-REGULATED 47）和 RD20（RESPONSIVE TO DEHYDRATION 20）的表达。我们的数据表明，PgNAC21 作为应激响应 NAC TF 发挥作用，可用于转基因方法开发作物植物的耐盐性。
