Author
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PARVEEN, IFFAT - University Of Mississippi |
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WANG, MEI - University Of Mississippi |
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ZHAO, JIANPING - University Of Mississippi |
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CHITTIBOYINA, AMAR - University Of Mississippi |
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TABANCA, NURHAYAT - University Of Mississippi |
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ALI, ABBAS - University Of Mississippi |
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Baerson, Scott |
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TECHEN, NATASCHA - University Of Mississippi |
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CHAPPELL, JOE - University Of Mississippi |
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KHAN, IKHLAS - University Of Mississippi |
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Pan, Zhiqiang - Peter |
Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/15/2015 Publication Date: 10/6/2015 Citation: Parveen, I., Wang, M., Zhao, J., Chittiboyina, A.G., Tabanca, N., Ali, A., Baerson, S.R., Techen, N., Chappell, J., Khan, I.A., Pan, Z. 2015. Investigating sesquiterpene biosynthesis in Ginkgo biloba: molecular cloning and functional characterization of (E,E)-farnesol and a-bisabolene synthases. Plant Molecular Biology. 89:451-462. Interpretive Summary: Terpenoids represent a large class of molecular compounds produced by a wide variety of plant species. Some of them may have medicinal values or pharmaceutical functions. Ginkgo biloba has been extensively investigated as a source of bioactive natural compounds, including terpenoids that accumulate in leaf tissues. Genomic data mining leads to the identification of two expressed sequence tags (ESTs) with high homology to plant terpene synthases, designated GbTPS1 and GbTPS2. Functional characterization of these clones using E.coli and yeast expression systems revealed that both enzymes possessed sesquiterpene synthase activities. The newly synthesized terpenes by GbTPS1 and GbTPS2 were identified as farnesol and a-bisabolene, respectively, by gas chromatography/mass spectrometry (GC/MS) and nuclear magnetic resonance (NMR) analyses Furthermore, the biting deterrent activity of alpha-bisabolene against mosquitoes was accessed and the results indicate its potential for development as a natural product-derived insect repellant. Technical Abstract: Ginkgo biloba is one of the oldest living tree species and has been extensively investigated as a source of bioactive natural compounds, including flavonoids, diterpene lactones, terpenoids and polysaccharides which accumulate in leaf tissues. Relatively few genes associated with biosynthetic pathways from ginkgo have been characterized to date, due in large part to the initial lack of publicly-available genome and transcriptome data. By mining a data set comprised of 64,057 expressed sequences derived from leaves of G. biloba, 16 candidate Expressed Sequence Tags (ESTs) potentially encoding enzymes associated with the biosynthesis of diterpenoid and terpenoids compounds were found, two of which were identified as putative terpene synthases (TPS). Here, the results for the cloning and functional characterization of GbTPS1 and GbTPS2, which were identified as farnesol and bisabolene synthases, respectively, are described. The amino acid sequence of both the enzymes showed DDXXD domains, characteristic of sesquiterpene synthases. The GbTPS2 gene product, alpha-bisabolene was tested for the first time in insect repellant assay and the proportion not biting (PNB) values against females Aedes Aegypti and Anophelese quadrimaculatus were found to be 0.78 and 0.59, respectively |