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Identification, functional characterization, and regulation of the enzyme responsible for floral (E)-nerolidol biosynthesis in kiwifruit (Actinidia chinensis).

Green SA, Chen X, Nieuwenhuizen NJ, Matich AJ, Wang MY, Bunn BJ, Yauk YK, Atkinson RG - J. Exp. Bot. (2011)

Bottom Line: Using a genomics-based approach, a single gene (AcNES1) was identified in an A. chinensis expressed sequence tag library that had significant homology to known floral terpene synthase enzymes.This result, together with subcellular protein localization to the cytoplasm, indicated that AcNES1 was acting as a (S)-(E)-nerolidol synthase in A. chinensis flowers.The synthesis of high (E,E)-farnesol levels appears to compete for the available pool of FDP utilized by AcNES1 for sesquiterpene biosynthesis and hence strongly influences the accumulation and emission of (E)-nerolidol in A. chinensis flowers.

View Article: PubMed Central - PubMed

Affiliation: The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand. sol.green@plantandfood.co.nz

ABSTRACT
Flowers of the kiwifruit species Actinidia chinensis produce a mixture of sesquiterpenes derived from farnesyl diphosphate (FDP) and monoterpenes derived from geranyl diphosphate (GDP). The tertiary sesquiterpene alcohol (E)-nerolidol was the major emitted volatile detected by headspace analysis. Contrastingly, in solvent extracts of the flowers, unusually high amounts of (E,E)-farnesol were observed, as well as lesser amounts of (E)-nerolidol, various farnesol and farnesal isomers, and linalool. Using a genomics-based approach, a single gene (AcNES1) was identified in an A. chinensis expressed sequence tag library that had significant homology to known floral terpene synthase enzymes. In vitro characterization of recombinant AcNES1 revealed it was an enzyme that could catalyse the conversion of FDP and GDP to the respective (E)-nerolidol and linalool terpene alcohols. Enantiomeric analysis of both AcNES1 products in vitro and floral terpenes in planta showed that (S)-(E)-nerolidol was the predominant enantiomer. Real-time PCR analysis indicated peak expression of AcNES1 correlated with peak (E)-nerolidol, but not linalool accumulation in flowers. This result, together with subcellular protein localization to the cytoplasm, indicated that AcNES1 was acting as a (S)-(E)-nerolidol synthase in A. chinensis flowers. The synthesis of high (E,E)-farnesol levels appears to compete for the available pool of FDP utilized by AcNES1 for sesquiterpene biosynthesis and hence strongly influences the accumulation and emission of (E)-nerolidol in A. chinensis flowers.

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Related in: MedlinePlus

Rates of sesquiterpene and monoterpene accumulation in A. chinensis flowers during a day/night cycle. Terpene volatiles were solvent extracted at 4-h intervals over the course of 24 h. Data are presented as mean ± SEM (n = 3). Means labelled without a common letter are significantly different (P < 0.05) based on LSD of one-way ANOVA.
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fig2: Rates of sesquiterpene and monoterpene accumulation in A. chinensis flowers during a day/night cycle. Terpene volatiles were solvent extracted at 4-h intervals over the course of 24 h. Data are presented as mean ± SEM (n = 3). Means labelled without a common letter are significantly different (P < 0.05) based on LSD of one-way ANOVA.

Mentions: Solvent extractions of flowers taken at the equivalent time points to the above headspace analysis were analysed for the presence of accumulated volatiles. In contrast to the emitted volatiles, the profile of accumulated volatiles was significantly less complex and primarily consisted of sesquiterpenes (Table 2). On a whole-flower fresh-weight basis, the dephosphorylated FDP derivative (E,E)-farnesol was by far the most prevalent compound occurring at ∼18,700 ng gFW−1, or ∼72%, of the total extracted terpene volatiles. The accumulated terpenes, presumed to be produced by TPS enzymes, were dominated by linalool and (E)-nerolidol, with ∼1500 and ∼890 ng gFW−1 respectively. Time point analysis of these terpenes (Fig. 2) showed that (E,E)-farnesol and (E)-nerolidol were largely accumulated during the day, with peak concentrations occurring at noon. Notably, the highest concentrations of accumulated (E)-nerolidol corresponded to the lowest rate of emitted (E)-nerolidol and vice versa, while linalool accumulation remained relatively constant over the course of the day/night cycle.


Identification, functional characterization, and regulation of the enzyme responsible for floral (E)-nerolidol biosynthesis in kiwifruit (Actinidia chinensis).

Green SA, Chen X, Nieuwenhuizen NJ, Matich AJ, Wang MY, Bunn BJ, Yauk YK, Atkinson RG - J. Exp. Bot. (2011)

Rates of sesquiterpene and monoterpene accumulation in A. chinensis flowers during a day/night cycle. Terpene volatiles were solvent extracted at 4-h intervals over the course of 24 h. Data are presented as mean ± SEM (n = 3). Means labelled without a common letter are significantly different (P < 0.05) based on LSD of one-way ANOVA.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3295389&req=5

fig2: Rates of sesquiterpene and monoterpene accumulation in A. chinensis flowers during a day/night cycle. Terpene volatiles were solvent extracted at 4-h intervals over the course of 24 h. Data are presented as mean ± SEM (n = 3). Means labelled without a common letter are significantly different (P < 0.05) based on LSD of one-way ANOVA.
Mentions: Solvent extractions of flowers taken at the equivalent time points to the above headspace analysis were analysed for the presence of accumulated volatiles. In contrast to the emitted volatiles, the profile of accumulated volatiles was significantly less complex and primarily consisted of sesquiterpenes (Table 2). On a whole-flower fresh-weight basis, the dephosphorylated FDP derivative (E,E)-farnesol was by far the most prevalent compound occurring at ∼18,700 ng gFW−1, or ∼72%, of the total extracted terpene volatiles. The accumulated terpenes, presumed to be produced by TPS enzymes, were dominated by linalool and (E)-nerolidol, with ∼1500 and ∼890 ng gFW−1 respectively. Time point analysis of these terpenes (Fig. 2) showed that (E,E)-farnesol and (E)-nerolidol were largely accumulated during the day, with peak concentrations occurring at noon. Notably, the highest concentrations of accumulated (E)-nerolidol corresponded to the lowest rate of emitted (E)-nerolidol and vice versa, while linalool accumulation remained relatively constant over the course of the day/night cycle.

Bottom Line: Using a genomics-based approach, a single gene (AcNES1) was identified in an A. chinensis expressed sequence tag library that had significant homology to known floral terpene synthase enzymes.This result, together with subcellular protein localization to the cytoplasm, indicated that AcNES1 was acting as a (S)-(E)-nerolidol synthase in A. chinensis flowers.The synthesis of high (E,E)-farnesol levels appears to compete for the available pool of FDP utilized by AcNES1 for sesquiterpene biosynthesis and hence strongly influences the accumulation and emission of (E)-nerolidol in A. chinensis flowers.

View Article: PubMed Central - PubMed

Affiliation: The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand. sol.green@plantandfood.co.nz

ABSTRACT
Flowers of the kiwifruit species Actinidia chinensis produce a mixture of sesquiterpenes derived from farnesyl diphosphate (FDP) and monoterpenes derived from geranyl diphosphate (GDP). The tertiary sesquiterpene alcohol (E)-nerolidol was the major emitted volatile detected by headspace analysis. Contrastingly, in solvent extracts of the flowers, unusually high amounts of (E,E)-farnesol were observed, as well as lesser amounts of (E)-nerolidol, various farnesol and farnesal isomers, and linalool. Using a genomics-based approach, a single gene (AcNES1) was identified in an A. chinensis expressed sequence tag library that had significant homology to known floral terpene synthase enzymes. In vitro characterization of recombinant AcNES1 revealed it was an enzyme that could catalyse the conversion of FDP and GDP to the respective (E)-nerolidol and linalool terpene alcohols. Enantiomeric analysis of both AcNES1 products in vitro and floral terpenes in planta showed that (S)-(E)-nerolidol was the predominant enantiomer. Real-time PCR analysis indicated peak expression of AcNES1 correlated with peak (E)-nerolidol, but not linalool accumulation in flowers. This result, together with subcellular protein localization to the cytoplasm, indicated that AcNES1 was acting as a (S)-(E)-nerolidol synthase in A. chinensis flowers. The synthesis of high (E,E)-farnesol levels appears to compete for the available pool of FDP utilized by AcNES1 for sesquiterpene biosynthesis and hence strongly influences the accumulation and emission of (E)-nerolidol in A. chinensis flowers.

Show MeSH
Related in: MedlinePlus