title: Engineering a Platform for Photosynthetic Pigment, Hormone and Cembrane-Related Diterpenoid Production in Nicotiana tabacum.
abstract: Plants synthesize a large number of isoprenoids that are of nutritional, medicinal and industrial importance. 1-Deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) catalyzes the first committed step for plastidial isoprenoid biosynthesis. Here, we identified two DXR isogenes, designated NtDXR1 and NtDXR2, from tetraploid common tobacco (Nicotiana tabacum L.). Southern blotting and genotyping analysis revealed that two NtDXR genes existed in the tetraploid tobacco genome; NtDXR1 and NtDXR2 were separately derived from N. tomentosiformis and N. sylvestris. Both NtDXRs were localized in chloroplasts. Expression patterns indicated that NtDXR1 and NtDXR2 had similar expression profiles. NtDXR genes were highly expressed in leaves with or without trichomes; expression was relatively reduced in ﬂowers and stems, weak in leaf trichomes and marginal in roots and seeds. Overexpressing NtDXR1 under control of the 35S promoter resulted in longer primary roots and enhancement of various photosynthetic pigments and hormones in leaves. In contrast, there were no significant changes in cembrane-related diterpenoids synthesized in glandular trichomes. To elucidate further the function of DXR in the biosynthesis of diterpenoids, overexpression vectors for NtDXR1 under the control of a trichome-specific CYP promoter were transferred to tobacco plants. CYP:NtDXR1 tobacco exhibited larger glandular cells and increased cembrane-related diterpenoids in leaf glandular trichomes. Moreover, transcripts of eight MEP (2-C-methyl-d-erythritol 4-phosphate) pathway genes were significantly up-regulated in NtDXR1-overexpressing tobacco plants, indicating that overexpression of NtDXR could boost the expression of downstream genes in the MEP pathway. Our results suggested that overexpression of NtDXR1 could increase the levels of photosynthetic pigments, leaf surface exudates and hormones though the MEP pathway.
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
authors.forename: Hongying
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
authors.forename: Dexin
authors.initials: D
authors.lastname: Niu
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
authors.forename: Songtao
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
authors.forename: Yongxia
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China.
authors.forename: Hongfang
authors.initials: H
authors.lastname: Jia
authors.affiliation: Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, China cuihonger_13@163.com.
authors.forename: Hong
authors.initials: H
authors.lastname: Cui
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D053898:Biosynthetic Pathways; D003001:Cloning, Molecular; D015870:Gene Expression; D005818:Genetic Engineering; D008969:Molecular Sequence Data; D010802:Phylogeny; D030821:Plants, Genetically Modified; D016415:Sequence Alignment; D013729:Terpenes / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics*
chemical_list: D013729:Terpenes; C114231:1-deoxy-D-xylulose 5-phosphate reductoisomerase; D019747:Aldose-Ketose Isomerases
keywords: 1-Deoxy-d-xylulose 5-phosphate reductoisomerase; Expression pattern; Glandular trichome; Isoprenoid; Morphological character; Transgenic tobacco