College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China.
Key Laboratory of Crop Growth Regulation of Hebei Province, Baoding, 071001, China.
Plant Cell Rep. 2020 Oct;39(10):1285-1299. doi: 10.1007/s00299-020-02564-6. Epub 2020 Jul 9.
Wheat MAPK gene TaMPK14 is N starvation response and is crucial in modulating plant low-N stress tolerance. Improving plant N use efficiency (NUE) contributes largely to the sustainable crop production worldwide. In this study, TaMPK14, a mitogen-activated protein kinase (MAPK) family gene in T. aestivum, was characterized for the role in mediating N starvation response. TaMPK14 harbors conserved domain/motifs specified by the plant MAPK proteins. In vitro assay for kinase activity of TaMPK14 validated its phosphorylation nature. TaMPK14 transcripts were upregulated in both roots and leaves under low-N treatment; moreover, the expression levels induced by N starvation were gradually restored following the N recovery progression. These results suggested transcriptional response of TaMPK14 upon the low-N stress. Compared with wild type (WT), the TaMPK14 overexpressing lines in N. tabacum displayed improved growth and N accumulation traits under deficient-N treatment, which indicated the crucial roles of the MAPK gene in mediating N starvation response. Additionally, the lines treated by N starvation were shown to be improved on cellular ROS homeostasis, displaying higher antioxidant enzymes (AE) activities and less ROS accumulative amount than WT. The transcripts of nitrate transporter gene NtNRT2.1 and those of AE genes NtSOD1, NtCAT1;2, and NtPOD4 were significantly upregulated in N-deprived TaMPK14 lines; overexpression of them conferred plants enhanced N uptake capacity and AE activities, respectively. Moreover, RNA-seq datasets generated from N-deprived transgenic lines contained numerous differential genes involving modulating various biological process, cellular component, and molecular function. Together, our investigation suggested that TaMPK14 improves plant N starvation response through transcriptional regulation of distinct NRT and AE genes as well as modulation of associated biological processes.
小麦 MAPK 基因 TaMPK14 对氮饥饿响应，在调节植物低氮胁迫耐受性方面至关重要。提高植物氮利用效率（NUE）对全球可持续作物生产有很大贡献。本研究中，对 T. aestivum 中的丝裂原活化蛋白激酶（MAPK）家族基因 TaMPK14 进行了氮饥饿响应调节作用的特征分析。TaMPK14 具有植物 MAPK 蛋白所特有的保守结构域/基序。体外激酶活性测定验证了 TaMPK14 的磷酸化性质。低氮处理下，TaMPK14 的转录本在根和叶中均上调；此外，氮饥饿诱导的表达水平随着氮的恢复而逐渐恢复。这些结果表明 TaMPK14 对低氮胁迫的转录响应。与野生型（WT）相比，在缺氮处理下，过表达 TaMPK14 的 N. tabacum 系表现出更好的生长和氮积累特性，这表明该 MAPK 基因在介导氮饥饿响应中起着关键作用。此外，经过氮饥饿处理的系表现出更好的细胞 ROS 稳态，显示出更高的抗氧化酶（AE）活性和更少的 ROS 积累量。硝酸盐转运基因 NtNRT2.1 的转录本和 AE 基因 NtSOD1、NtCAT1;2 和 NtPOD4 的转录本在氮饥饿的 TaMPK14 系中显著上调；它们的过表达分别赋予植物增强的氮吸收能力和 AE 活性。此外，从氮饥饿的转基因系生成的 RNA-seq 数据集包含了许多涉及调节各种生物学过程、细胞成分和分子功能的差异基因。总的来说，我们的研究表明，TaMPK14 通过对不同的 NRT 和 AE 基因的转录调控以及对相关生物学过程的调节来改善植物的氮饥饿响应。
