Sung-Min Jung

Transcriptional analysis of Dehydrin1 genes responsive to dehydrating stress in grapevines

Dehydrins (DHNs) are proteins that are induced under dehydrating stress conditions such as drought, cold, and salinity. We investigated the expression of the DHN1 genes over time after drought treatment for 14 days and subsequent rehydration in the Korean native species, Vitis flexuosa, main cultivars ‘Campbell Early’ (Vitis spp.) and ‘Tamnara’ (Vitis spp.). Two highly homologous dehydrins, DHN1a and DHN1b, were isolated from ‘Campbell Early’ and ‘Tamnara’ grapevines, but only DHN1a cDNA was cloned from V. flexuosa leaves. Amino acid sequences of DHN1 deduced from five cDNAs of DHN1a/b from three grapevines were of the YSK2-type having the Y-, S-, and K-domain. Analysis of expression using quantitative real-time polymerase chain reaction and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) revealed that expression of the DHN1a and DHN1b genes was induced earlier in V. flexuosa under drought stress conditions than in ‘Campbell Early’ and ‘Tamnara’. During drought stress, a large amount of DHN1a and DHN1b was continuously expressed. V. flexuosa could be a resource in stress-tolerant grape breeding for enhancing drought tolerance.

Changes in the aromatic composition of grape cv. Cheongsoo wine depending on the degree of grape ripening

The volatile composition and properties of wine made using the ‘Cheongsoo’ grape cultivar harvested at different stages of ripening were evaluated. There were changes in the chemical composition of ‘Cheongsoo’ wine, including pH, total acidity, total polyphenols, and tannins according to the degree of grape ripening. Colorimetric analysis indicated that wines had yellow tones and deep and very strong colors with a high chromatic intensity depending on the degree of grape ripening. Of 87 detected flavor compounds, 26 had high OAV (odor active values). Based on OAV, 26 compounds were considered to be important odorants for ‘Cheongsoo’ wine. A harvest date of September 19 showed good separation from August 29 and September 8 and 29, depending on the degree of grape ripening, on a principle components analysis plot for grape ripening. More volatile compounds were present in September 19 harvested grapes.

Regional Differences of Leaf Spot Disease on Grapevine cv. `Campbell Early` Caused by Pseudocercospora vitis in Plastic Green House

Pseudocercospora leaf spot was major disease of grape cultivar `Campbell Early` in Korea. Leaf spot first appeared in early June and rapidly dispersed to other leaves through rainy season. Disease progress of leaf spot by Pseudocercospora vitis in plastic green house, in the two provinces (Gimje and Gimcheon), were investigated in 2007. Differences of Infected leaves (%) between cultivation systems were observed in field and plastic green house, but there was no difference between provinces. Micro environmental factors, such as temperature and relative humidity, were correlated with infected leaves by PROC REG procedure of SAS (Statistical Analysis System). As a result, regression model best described (

Transcript profiling of native Korean grapevine species Vitis flexuosa exposed to dehydration and rehydration treatment

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Pre-bloom application of gibberellin in ‘Tamnara’ grape increases γ-aminobutyric acid (GABA) production at full bloom

Vitis flexuosa, a native Korean wild grapevine species, is more tolerant to abiotic stress than cultivated grapevines, but little is known about the mechanism underlying this tolerance. To better characterize the responses of V. flexuosa to drought stress and subsequent rehydration, we treated V. flexuosathe plants with four stress conditions: short- and long-term dehydration, rehydration immediately after long-term drought, and long-term rehydration after long-term drought. We examined gene expression profiles in response to these treatments using whole-genome microarray analysis at 12X coverage (using the NimbleGen protocol). We identified a 5,964 genes that were differentially expressed between the stress treatments and the well-watered control. Gene ontology analysis showed that most of the differentially expressed genes (DEGs), regardless of treatment, participate in the metabolism of proteins or phosphatecontaining compounds and function in the binding of metal ions, as kinases, or as phosphotransferases. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that genes involved in secondary metabolite biosynthesis were downregulated during dehydration but upregulated during rehydration. Among the DEGs encoding transcription factors, genes in the MYB family were the most common differentially genes in all treatment groups. The NAC family was the second most common group during dehydration, while the AP2/ERF family was the second most common during rehydration. These results will help elucidate the mechanisms underlying the response of V. flexuosa to drought stress and will be valuable for breeding drought-tolerant grapevines.

Application of Color Index for Red Grapes (CIRG) for Assessment of Grape Quality

A pre-bloom application of gibberellin (GA) on grapevines (Vitis spp.) induces fruit set without fertilization (parthenocarpy) by inhibiting pollen tube growth. In the present study, we analyzed transcriptional changes in the Vitis γ-aminobutyric acid (GABA) metabolic genes and the levels of GABA in grapevines with or without GA treatment to understand how GA induces parthenocarpy in grapevines. Four Vitis glutamate decarboxylases (VvGAD), two GABA transaminases (VvGABA-T), and three succinic semialdehyde dehydrogenases (VvSSADH) were identified in grapevines, and their expression patterns were analyzed during inflorescence development from 14 days before full bloom (DBF) to 5 days after full bloom (DAF). Without GA treatment, we observed simultaneously high expression levels of VvGAD1 and VvGABA-T2, with low levels of GABA from 10 to 5 DBF. With GA application, the levels of GABA were mostly unaltered, and the expression levels of VvGAD1 and VvGABA-T2 were around 30% lower compared to the plants without GA treatment at 12 DBF. However, at near full bloom in the plants treated with GA, GABA levels increased more than two-fold and VvGAD1 was upregulated. These results indicate that GABA levels are tightly regulated by VvGAD1 and VvGABA-T2 before pollination and that application of GA alters the pattern of GABA accumulation at near full bloom. This is the first report to describe how treatment with GA disrupts the crosstalk between the pistil and pollen via changes in GABA metabolism during GA-mediated parthenocarpic fruit initiation.

Transcriptional changes of gibberellin oxidase genes in grapevines with or without gibberellin application during inflorescence development.

Hunter value (L*, a*, b*) is a rapid and convenience method for compare with different skin color, but not suitable to compare quality with various grape cultivars. Color Index for Red Grapes (CIRG) is one of a simply convert method for grape skin color as numeric data, and many previously result showed that high correlation between CIRG index and various quality factors of grape. In this experiment, we measured CIRG index, total soluble solids (TSS), titratable acidity (TA), and total anthocyanin content on the grapes (Campbell Early, Heukbosuk, Kyoho) from the varaison to harvest. As a result, CIRG index and anthocyanin contents have an exponential correlation; r-square is each 0.8595 in the ‘Campbell Early’ and 0.8500 in ‘Heukbosuk’. And TSS and CIRG index have a positive r-square, at the Campbell Early is 0.7758 and Heukbosuk is 0.7253. Also TA and CIRG index have a positive r-square, at the Campbell Early is 0.7279 and Heukbosuk is 0.6630. These results were shown that CIRG index is a reliable indicator for a none-destructive evaluation of the grape quality. Additional key words : color space, colorimeter, regression analysis