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Plant Cell

Title:		Clustered transcription factor genes regulate nicotine biosynthesis in tobacco
Author(s):		Shoji T; Kajikawa M; Hashimoto T;
Address:		"Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan"
Journal Title:		Plant Cell
Year:		2010
Volume:		20101019
Issue:		10
Page Number:		3390 - 3409
DOI:		10.1105/tpc.110.078543
ISSN/ISBN:		1532-298X (Electronic) 1040-4651 (Print) 1040-4651 (Linking)
Abstract:		"Tobacco (Nicotiana tabacum) synthesizes nicotine and related pyridine alkaloids in the root, and their synthesis increases upon herbivory on the leaf via a jasmonate-mediated signaling cascade. Regulatory NIC loci that positively regulate nicotine biosynthesis have been genetically identified, and their mutant alleles have been used to breed low-nicotine tobacco varieties. Here, we report that the NIC2 locus, originally called locus B, comprises clustered transcription factor genes of an ethylene response factor (ERF) subfamily; in the nic2 mutant, at least seven ERF genes are deleted altogether. Overexpression, suppression, and dominant repression experiments using transgenic tobacco roots showed both functional redundancy and divergence among the NIC2-locus ERF genes. These transcription factors recognized a GCC-box element in the promoter of a nicotine pathway gene and specifically activated all known structural genes in the pathway. The NIC2-locus ERF genes are expressed in the root and upregulated by jasmonate with kinetics that are distinct among the members. Thus, gene duplication events generated a cluster of highly homologous transcription factor genes with transcriptional and functional diversity. The NIC2-locus ERFs are close homologs of ORCA3, a jasmonate-responsive transcriptional activator of indole alkaloid biosynthesis in Catharanthus roseus, indicating that the NIC2/ORCA3 ERF subfamily was recruited independently to regulate jasmonate-inducible secondary metabolism in distinct plant lineages"
Keywords:		"Cyclopentanes/metabolism Gene Expression Regulation, Plant Molecular Sequence Data Multigene Family Nicotine/*biosynthesis Oligonucleotide Array Sequence Analysis Oxylipins/metabolism Plant Proteins/genetics/*metabolism Plant Roots/genetics/metabolism Pla;"
Notes:		"MedlineShoji, Tsubasa Kajikawa, Masataka Hashimoto, Takashi eng Research Support, Non-U.S. Gov't England 2010/10/21 Plant Cell. 2010 Oct; 22(10):3390-409. doi: 10.1105/tpc.110.078543. Epub 2010 Oct 19"