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Genes (Basel)

Title:		Increased Leaf Nicotine Content by Targeting Transcription Factor Gene Expression in Commercial Flue-Cured Tobacco (Nicotiana tabacum L.)
Author(s):		Liu H; Kotova TI; Timko MP;
Address:		"Department of Biology, University of Virginia, Charlottesville, VA 22904, USA"
Journal Title:		Genes (Basel)
Year:		2019
Volume:		20191114
Issue:		11
Page Number:		-
DOI:		10.3390/genes10110930
ISSN/ISBN:		2073-4425 (Electronic) 2073-4425 (Linking)
Abstract:		"Nicotine, the most abundant pyridine alkaloid in cultivated tobacco (Nicotiana tabacum L.), is a potent inhibitor of insect and animal herbivory and a neurostimulator of human brain function. Nicotine biosynthesis is controlled developmentally and can be induced by abiotic and biotic stressors via a jasmonic acid (JA)-mediated signal transduction mechanism involving members of the APETALA 2/ethylene-responsive factor (AP2/ERF) and basic helix-loop-helix (bHLH) transcription factor (TF) families. AP2/ERF and bHLH TFs work combinatorically to control nicotine biosynthesis and its subsequent accumulation in tobacco leaves. Here, we demonstrate that overexpression of the tobacco NtERF32, NtERF221/ORC1, and NtMYC2a TFs leads to significant increases in nicotine accumulation in T2 transgenic K326 tobacco plants before topping. Up to 9-fold higher nicotine production was achieved in transgenics overexpressing NtERF221/ORC1 under the control of a constitutive GmUBI3 gene promoter compared to wild-type plants. The constitutive 2XCaMV35S promoter and a novel JA-inducible 4XGAG promoter were less effective in driving high-level nicotine formation. Methyljasmonic acid (MeJA) treatment further elevated nicotine production in all transgenic lines. Our results show that targeted manipulation of NtERF221/ORC1 is an effective strategy for elevating leaf nicotine levels in commercial tobacco for use in the preparation of reduced risk tobacco products for smoking replacement therapeutics"
Keywords:		"Acetates/metabolism Alkaloids/biosynthesis/toxicity Anabasine/biosynthesis/toxicity Cyclopentanes/metabolism Ethylenes/metabolism Gene Expression Regulation, Plant Helix-Loop-Helix Motifs/genetics Nicotine/analogs & derivatives/*biosynthesis/economics/tox;"
Notes:		"MedlineLiu, Hai Kotova, Tatyana I Timko, Michael P eng Research Support, Non-U.S. Gov't Switzerland 2019/11/20 Genes (Basel). 2019 Nov 14; 10(11):930. doi: 10.3390/genes10110930"