High Temperature Induces Expression of Tobacco Transcription Factor NtMYC2a to Regulate Nicotine and JA Biosynthesis.
Environmental stress elevates the level of jasmonic acid (JA) and activates the biosynthesis of nicotine and related pyridine alkaloids in tobacco (Nicotiana tabacumL.) by up-regulating the expression of putrescineN-methyltransferase 1 (NtPMT1), which encodes a putrescineN-methyl transferase that catalyzes nicotine formation. The JA signal suppressor JASMONATE ZIM DOMAIN 1 (NtJAZ1) and its target protein, NtMYC2a, also regulate nicotine biosynthesis; however, how these proteins interact to regulate abiotic-induced nicotine biosynthesis is poorly understood. In this study, we found that high-temperature (HT) treatment activated transcription ofNtMYC2a, which subsequently stimulated the transcription of genes associated with JA biosynthesis, includingLipoxygenase(LOX),Allene oxide synthase(AOS),Allene oxide cyclase(AOC), and12-oxophytodienodate reductase(OPR). Overexpression ofNtMYC2aincreased nicotine biosynthesis by enhancing its binding to the promoter ofNtPMT1. Overexpression of eitherNtJAZ1or proteasome-resistantNtJAZ1ΔCsuppressed nicotine production under normal conditions, but overexpression only of the former resulted in low levels of nicotine under HT treatment. These data suggest that HT induces NtMYC2a accumulation through increased transcription to activate nicotine synthesis; meanwhile, HT-induced NtMYC2a can activate JA synthesis to promote additional NtMYC2a activity by degrading NtJAZ1 at the post-transcriptional level.
Jiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environment Protection, Jiangsu Key Laboratory for Eco-Agriculture Biotechnology around Hongze Lake, Huaiyin Normal UniversityHuaian, China; Department of Plant Pathology, University of GeorgiaTifton, GA, USA.
Liming
L
Yang
Department of Agronomy, Yunnan Academy of Tobacco Agricultural Sciences Kunming, China.
Junying
J
Li
Jiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environment Protection, Jiangsu Key Laboratory for Eco-Agriculture Biotechnology around Hongze Lake, Huaiyin Normal University Huaian, China.
Jianhui
J
Ji
Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University Shanghai, China.
Ping
P
Li
Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University Shanghai, China.
Liangliang
L
Yu
Plant Production Department, College of Food and Agricultural Sciences, King Saud UniversityRiyadh, Saudi Arabia; Seed Pathology Department, Plant Pathology Research Institute, Agriculture Research CenterGiza, Egypt.
Elsayed F
EF
Abd Allah
Jiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environment Protection, Jiangsu Key Laboratory for Eco-Agriculture Biotechnology around Hongze Lake, Huaiyin Normal University Huaian, China.
Yuming
Y
Luo
Laboratory of Tobacco Agriculture, Zhengzhou Tobacco Research Institute of CNTC Zhengzhou, China.
Liwei
L
Hu
Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University Shanghai, China.
Xiangyang
X
Hu
Jasmonic acid; NtMYC2a gene; expression regulation; high temperature stress; nicotine biosynthesis; protein interactions