Abstract: 【Objective】 The aim of this study was to detect the terpenes and their contents in Alexandria grape, analyze the terpenes accumulation and genes transcript profiles related to their biosynthesis in developing grape berries, to elucidate the regulation of aromatic components for breeding of aromatic grapes. 【Method】 The berries were sampled once a week from veraison to full mature stage, 80-100 berries were randomly chosen, seeds and pedicels were removed, then crushed into juice, after centrifuged, the supernatant was prepared for detection of aromatic substances. Volatile components were extracted by head space solid phase micro extraction method, the compounds were identified by a combination of matching retention index and time with NIST05 library and authentic standards, the compounds were quantified using the internal standard. The primers were designed according to the ORF sequence of DXS gene, RNA of full ripening berries were reverse transcripted into cDNA, which was used as a template to amplify OFR fragments. DXS gene of Alexandria grape was obtained through several times of independent PCR, and single nucleotide polymorphism sites were found by blast of sequence results. Primers of eight key genes in the terpenes biosynthesis pathway were designed, three housekeeping genes of Ubiquitin, EF1-α and GAPDH were used as internal references, transcription abundance of these genes were detected by real-time PCR. 【Result】 The contents of linalool and geraniol were much higher than other monoterpenes, the concentration of various terpenes increased from veraison to ripening, linalool, myrcene and limonene increased by 6-8 times, geraniol, terpineol, geranial and terpinolene increased by 2 to 3 times, rose oxide and neral increased slightly. The concentrations of linalool, gerniol, rose oxide and myrcene were higher than their odor threshold. In the early pathway of monoterpenes biosynthesis, DXS1 gene was gradually up-regulated from veraison and increased by 5 times at the time of 15 weeks after blossom (15WAB). DXS3 gene was up-regulated from 12WAB and DXR gene showed a fluctuating trend, the relative expression level of HDR gene was most abundant in the early pathway and reached 10 to 20 times of DXS1, DXS3 and DXR genes. FPPS gene was up-regulated by 4 times and GPPS by 2 times in the middle pathway, Liner-syn gene and Terp-syn gene were up-regulated from 11 to 15 WAB in the late pathway, and all the genes were down-regulated significantly from 17 WAB. The total contents of monoterpenes accumulated drastically from 12 to 16 WAB, which were in accordance with the expression trend of DXS3, DXR, HDR, GPPS and FPPS genes, the correlation coefficient of total terpenes to DXS3 was 0.831. The ORF length of DXS1 gene was 2 151 bp, it encoded 716 amino acids, 16 single nucleotide polymorphism sites were found by blast of 20 independent sequence results, which caused the change of 4 amino acids.【Conclusion】In the pathway of terpenes biosynthesis, many genes were up-regulated at late-ripening stage, which led to two-eight fold increase of terpenes. DXS3 gene expression was correlated significantly to the total content of terpenes.

Key words: Alexandria grape , monotterpenes , biosynthesis , RT-PCR