Post-translational control of biotic stress-related nicotine biosynthesis by a MAP kinase signaling cascade

Authors

• Yan Zhou, University of Kentucky
• Yongliang Liu, University of KentuckyFollow
• Ruiqing Lyu, University of KentuckyFollow
• Sanjay Kumar Singh, University of KentuckyFollow
• Xueyi Sui, Yunnan Academy of Tobacco Agricultural Sciences
• Xin Hou, Shandong Agricultural University
• Sitakanta Pattanaik, University of KentuckyFollow
• Ling Yuan, University of KentuckyFollow

Abstract

The evolutionarily conserved mitogen-activated protein kinase (MAPK) cascades relay extracellular signals into cells, triggering a variety of cellular responses. We previously revealed NtMPK4 as a positive regulator of nicotine biosynthesis; however, its upstream regulation remains unclear. Here, we characterized a MAPK cascade, comprising NtMEKK1b, NtMPKK2a, and NtMPK4, that promotes nicotine biosynthesis. This signaling module transduces external cues, including jasmonate and pathogen elicitors such as flg22, into post-translational modifications that enhance transcriptional activity and pathway gene expression. NtMPKK2a physically interacts with and phosphorylates NtMPK4 in vivo, confirming its role as an upstream kinase. RNAi-mediated silencing of NtMPKK2a significantly reduced the expression of nicotine pathway genes and decreased nicotine accumulation, whereas induced-overexpression of NtMPKK2a upregulated nicotine pathway genes and increased nicotine contents in tobacco hairy roots. Overexpression of NtMPKK2a in tobacco cells enhanced the transactivation activity of a NIC2-locus Ethylene Response Factor NtERF221 on Putrescine N-methyltransferase (NtPMT) promotor, further supporting its role in promoting nicotine biosynthesis. Furthermore, we identified NtMEKK1b, a tobacco MEKK that interacts with NtMAPKK2a in yeast cells. Knock-down of NtMEKK1b in transgenic tobacco plants attenuated the expression of nicotine pathway genes and reduced nicotine contents, whereas induced-overexpression of NtMEKK1b upregulated gene expression and nicotine accumulation. Our findings uncover a previously uncharacterized MAPK cascade module, NtMEKK1b-NtMPKK2a-NtMPK4, that regulates nicotine biosynthesis, highlighting the importance of posttranslational regulation in nicotine biosynthesis.

Document Type

Article

Publication Date

2-1-2026

Notes/Citation Information

Publisher Copyright: © 2025 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/

Digital Object Identifier (DOI)

10.1016/j.cj.2025.08.012

Archival?

Archival

Repository Citation

Zhou, Yan; Liu, Yongliang; Lyu, Ruiqing; Singh, Sanjay Kumar; Sui, Xueyi; Hou, Xin; Pattanaik, Sitakanta; and Yuan, Ling, "Post-translational control of biotic stress-related nicotine biosynthesis by a MAP kinase signaling cascade" (2026). Plant and Soil Sciences Faculty Publications. 205.
https://uknowledge.uky.edu/pss_facpub/205