Articles
MONOTERPENE ACCUMULATION AND ITS BIOSYNTHESIS: GENE TRANSCRIPT PROFILES OF TWO GRAPE CULTIVARS DURING BERRY DEVELOPMENT
Article number
1082_2
Pages
37 – 42
Language
English
Abstract
The aim of this study was to analyze monoterpene accumulation and the biosynthesis gene transcripts profiles during the berry development of two types of grape cultivars: Muscat Alexandria with a strong Muscat flavor and Moldova with neutral flavor.
The samples were collected every ten days from veraison to the fully ripened stage.
The monoterpene concentration was measured by gas chromatography and mass spectrometry using head space solid phase micro-extraction method.
Seven genes in the monoterpene synthesis pathway were chosen to study their transcription by real-time PCR.
For Muscat Alexandria, the concentration of various monoterpenes increased from veraison to ripening.
Linalool, β-myrcene and limonene increased
6- to 8-fold, geraniol, terpineol and geranial increased 2- to 3-fold, rose oxide and neral increased slightly.
The most abundant monoterpenes were linalool and geraniol, the concentrations were above their odor threshold.
In Moldova, monoterpenes were all only detected as traces.
At the transcription level, for both cultivars, DXS3, DXR, HDR and α-Terp gene were up regulated from veraison to 20 days weeks after veraison but the relative expression of these genes in Muscat Alexandria was higher than in Moldova. The Liner-syn gene showed slight changes during berry development.
For the cultivar of Muscat Alexandria, the correlation coefficient between the total content in monoterpene and the gene transcript abundance of DXS3 and α-Terp was 0.831 and 0.884, respectively, suggesting that these two genes may serve as biomarker for monoterpene accumulation.
The full ORF of the DXS1 gene was cloned and sequenced for the two cultivars. 8 SNPs and 16 SNPs were found for Moldova and Muscat Alexandria respectively. Muscat Alexandria, like most of the Muscat-flavored genotypes, is heterozygous at the VvDXS locus, thus containing a Muscat-type allele (284N) and a neutral allele (284K) as well, while Moldova is homozygous at the VvDXS locus, containing only a neutral allele (284K).
The samples were collected every ten days from veraison to the fully ripened stage.
The monoterpene concentration was measured by gas chromatography and mass spectrometry using head space solid phase micro-extraction method.
Seven genes in the monoterpene synthesis pathway were chosen to study their transcription by real-time PCR.
For Muscat Alexandria, the concentration of various monoterpenes increased from veraison to ripening.
Linalool, β-myrcene and limonene increased
6- to 8-fold, geraniol, terpineol and geranial increased 2- to 3-fold, rose oxide and neral increased slightly.
The most abundant monoterpenes were linalool and geraniol, the concentrations were above their odor threshold.
In Moldova, monoterpenes were all only detected as traces.
At the transcription level, for both cultivars, DXS3, DXR, HDR and α-Terp gene were up regulated from veraison to 20 days weeks after veraison but the relative expression of these genes in Muscat Alexandria was higher than in Moldova. The Liner-syn gene showed slight changes during berry development.
For the cultivar of Muscat Alexandria, the correlation coefficient between the total content in monoterpene and the gene transcript abundance of DXS3 and α-Terp was 0.831 and 0.884, respectively, suggesting that these two genes may serve as biomarker for monoterpene accumulation.
The full ORF of the DXS1 gene was cloned and sequenced for the two cultivars. 8 SNPs and 16 SNPs were found for Moldova and Muscat Alexandria respectively. Muscat Alexandria, like most of the Muscat-flavored genotypes, is heterozygous at the VvDXS locus, thus containing a Muscat-type allele (284N) and a neutral allele (284K) as well, while Moldova is homozygous at the VvDXS locus, containing only a neutral allele (284K).
Authors
L. Sun, B.Q. Zhu, X.R. Sun, X.Q. Xu, G.J. Zhang, A.L. Yan, H.Y. Xu
Keywords
Vitis, monoterpenoids, synthesis, expression, veraison
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