title: A three-component gene expression system and its application for inducible flavonoid overproduction in transgenic Arabidopsis thaliana.
abstract: Inducible gene expression is a powerful tool to study and engineer genes whose overexpression could be detrimental for the host organisms. However, only limited systems have been adopted in plant biotechnology. We have developed an osmotically inducible system using three components of plant origin, RD29a (Responsive to Dehydration 29A) promoter, CBF3 (C-repeat Binding Factor 3) transcription factor and cpl1-2 (CTD phosphatase-like 1) mutation. The osmotic stress responsible RD29a promoter contains the CBF3 binding sites and thus RD29A-CBF3 feedforward cassette enhances induction of RD29a promoter under stress. The cpl1-2 mutation in a host repressor CPL1 promotes stress responsible RD29a promoter expression. The efficacy of this system was tested using PAP1 (Production of Anthocyanin Pigment 1) transgene, a model transcription factor that regulates the anthocyanin pathway in Arabidopsis. While transgenic plants with only one or two of three components did not reproducibly accumulate anthocyanin pigments above the control level, transgenic cpl1 plants containing homozygous RD29a-PAP1 and RD29a-CBF3 transgenes produced 30-fold higher level of total anthocyanins than control plants upon cold treatment. Growth retardation and phytochemical production of transgenic plants were minimum under normal conditions. The flavonoid profile in cold-induced transgenic plants was determined by LC/MS/MS, which resembled that of previously reported pap1-D plants but enriched for kaempferol derivatives. These results establish the functionality of the inducible three-component gene expression system in plant metabolic engineering. Furthermore, we show that PAP1 and environmental signals synergistically regulate the flavonoid pathway to produce a unique flavonoid blend that has not been produced by PAP1 overexpression or cold treatment alone.
authors.affiliation: Vegetable and Fruit Improvement Center, Department of Horticultural Science, Texas A&M University, College Station, Texas, United States of America.
authors.forename: Yue
authors.initials: Y
authors.lastname: Feng
authors.forename: Cong-Mei
authors.initials: CM
authors.lastname: Cao
authors.forename: Meenu
authors.initials: M
authors.lastname: Vikram
authors.forename: Sunghun
authors.initials: S
authors.lastname: Park
authors.forename: Hye Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jong Chan
authors.initials: JC
authors.lastname: Hong
authors.forename: Luis
authors.initials: L
authors.lastname: Cisneros-Zevallos
authors.forename: Hisashi
authors.initials: H
authors.lastname: Koiwa
mesh_terms: D000872:Anthocyanins / Q000096:biosynthesis*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D003080:Cold Temperature; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005821:Genetic Techniques; D006720:Homozygote; D013058:Mass Spectrometry; D009997:Osmotic Pressure; D000073718:Pancreatitis-Associated Proteins; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D019076:Transgenes / Q000235:genetics
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; D000073718:Pancreatitis-Associated Proteins; C000612141:REG3A protein, human; D014157:Transcription Factors