Mitogen-Activated Protein Kinases Associated Sites of Tobacco Repression of Shoot Growth Regulates Its Localization in Plant Cells

作者：Wang, Luyao^*; Gui, Ying; Yang, Bingye; Dong, Wenpan; Xu, Peiling; Si, Fangjie; Yang, Wei; Luo, Yuming; Guo, Jianhua; Niu, Dongdong; Jiang, Chunhao

来源：INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES, 2022, 23(16): 8941.

DOI：10.3390/ijms23168941

• MAPK
• phosphorylation
• RSG
• abiotic stress
• protein interaction

Plant defense and growth rely on multiple transcriptional factors (TFs). Repression of shoot growth (RSG) is a TF belonging to a bZIP family in tobacco, known to be involved in plant gibberellin feedback regulation by inducing the expression of key genes. The tobacco calcium-dependent protein kinase CDPK1 was reported to interact with RSG and manipulate its intracellular localization by phosphorylating Ser-114 of RSG previously. Here, we identified tobacco mitogen-activated protein kinase 3 (NtMPK3) as an RSG-interacting protein kinase. Moreover, the mutation of the predicted MAPK-associated phosphorylation site of RSG (Thr-30, Ser-74, and Thr-135) significantly altered the intracellular localization of the NtMPK3-RSG interaction complex. Nuclear transport of RSG and its amino acid mutants (T30A and S74A) were observed after being treated with plant defense elicitor peptide flg22 within 5 min, and the two mutated RSG swiftly re-localized in tobacco cytoplasm within 30 min. In addition, triple-point mutation of RSG (T30A/S74A/T135A) mimics constant unphosphorylated status, and is predominantly localized in tobacco cytoplasm. RSG (T30A/S74A/T135A) showed no re-localization effect under the treatments of flg22, B. cereus AR156, or GA(3), and over-expression of this mutant in tobacco resulted in lower expression levels of downstream gene GA20ox1. Our results suggest that MAPK-associated phosphorylation sites of RSG regulate its localization in tobacco, and that constant unphosphorylation of RSG in Thr-30, Ser-74, and Thr-135 keeps RSG predominantly localized in cytoplasm.

• 单位
  南京农业大学