Seon Ae Kim

Comparison of accumulation of stilbene compounds and stilbene related gene expression in two grape berries irradiated with different light sources

In this study, the accumulation of stilbene compounds and the expression of genes related to their syntheses in ‘Campbell Early’ and ‘Kyoho’ grapes (Vitis sp.) were investigated by irradiating the harvested berries with four different light sources (white fluorescent and purple, blue, and red LED lights) for 48 hours. The total concentrations of five stilbene derivatives at 24 hours after irradiation differed in response to different light sources and cultivars. The accumulation of stilbenic compounds in the skins of two grape cultivars and the expression of PAL and STS1 genes were mainly induced under red and blue LED lights. The expression of PAL, CHS, CHI, STS1, STS12, and ROMT was differently induced in response to irradiation with different light sources in both grape cultivars. The mRNA levels of PAL and STS1 were higher than those of CHS, CHI, STS12 and ROMT in the two grapes berries. Overall, the results of this study indicated that red and blue LED induced the accumulation of stilbene compounds and the expression of genes related to their syntheses in grape berries, suggesting that irradiation with LEDs can be used to induce the accumulation of phytochemicals that have positive impacts on human health via the induction of related genes.

Transcriptome analysis of grapevine shoots exposed to chilling temperature for four weeks

Low temperature is an important factor that can limit the growth of grapevine (Vitis spp.). In this study, we analyzed the transcriptome of grapevine shoots exposed to cold temperatures to identify genes expressed specifically at low temperature, determine their function based on GO-term analysis, and compare their differential expression. We analyzed two varieties that differed in cold tolerance, the more-tolerant ‘Campbell Early’ and the less-tolerant ‘Kyoho’ grapevine varieties. This was accomplished through annotation of data from sequencing short reads on the Solexa platform. We assembled more than 120 million high-quality trimmed reads using Velvet followed by Oases. Functional categorization of up-regulated transcripts revealed the conservation of genes involved in various biological processes including cellular processes, primary metabolic processes, and biological regulation. The major up-regulated genes in ‘Campbell Early’ included loci encoding response regulator 20, expansin-like B1, a leucine-rich repeat (LRR) family protein, and galactinol synthase 2. The major down-regulated genes in ‘Campbell Early’ included loci encoding fasciclinlike arabinogalactan 9, a GDSL-like lipase/acylhydrolase superfamily protein, early nodulin-like protein 14, and trichome birefringence-like 38. The differential expression observed by sequence analysis was confirmed by real-time PCR. Genes encoding a non-specific serine/threonine protein kinase, peroxidase, and ubiquitin-protein ligase showed reduced expression in response to low temperature in both grapevine varieties. Transcriptome analysis of shoots exposed to chilling could lead to new insights into the molecular basis of tolerance to low-temperature in grapevine.

INHIBITING WILDFIRE AND INDUCING DEFENSE-RELATED GENE EXPRESSION BY LED TREATMENT ON NICOTIANA BENTHAMIANA

Light plays an important role in the induction of resistance responses in various plants against diseases. In this study, the inhibition was investigated of wildfire disease caused by Pseudomonas syringae pv. tabaci in Nicotiana benthamiana in response to irradiation with light emitting diodes (LEDs) To identify the effects of various wavelengths on the induction of defense responses, N. benthamiana plants were irradiated for three days with various LEDs (380, 440, 470, and 660 nm) before and after inoculation. Symptom development showed greater suppression in response to irradiation with blue (440 nm) and red (660 nm) light than fluorescent lights. Additionally, fewer bacterial cells were recovered from the lesions of LEDtreated leaves than those of fluorescent light-treated leaves. Simple LED irradiation induced the expression of defense-related genes including catalase (CAT), chalcone synthase (CHS), gluthatione-S-transferase (GST), pathogenesis-related protein (PR Q), proteinase inhibitor II (PinII), and thaumatin-like protein (TLP). Taken together, these data suggest that irradiation by LEDs could inhibit wildfire development by inducing defense responses in N. benthamiana plants.

Accumulation of stilbene compounds and induction of related gene expression by hairy vetch and ryegrass extracts in grape berries

The present study investigated the accumulation of stilbene compounds (trans- and cis-resveratrol, piceides, and piceatannol) and induction of gene expression related to their synthesis in the berries of ‘Campbell Early’ and ‘Kyoho’ grapes following treatment with water-based shoot extracts from hairy vetch and ryegrass. Trans-resveratrol was present in substantial amounts (4.1 ± 0.0 to 5.3 ± 0.07 μg/g fresh weight) in ‘Campbell Early’ and (7.6 ± 1.24 to 10.4 ± 0.35 07 μg/g fresh weight) in ‘Kyoho’, whereas trace amounts of cis-resveratrol were detected in treated grape berries. Moreover, the concentration of piceid and piceatannol in berries of both cultivars was markedly enhanced in response to treatment with plant extracts. Accumulation of stilbene compounds in berries increased at 24 h after treatment with the test extracts. Moreover, berries treated with extracts showed increased transcript levels of genes encoding enzymes involved in stilbene compound biosynthesis. Changes in the content of stilbene compounds were correlated with levels of stilbene synthase mRNA, indicating transcriptional control of stilbene synthase activity. Additionally, pre-treatment with the tested extracts resulted in reduced lesion size in berries inoculated with Botrytis cinerea. These results suggest that hairy vetch/ryegrass extracts can be used to elicit resistance responses against pathogen infection in grape berries.

In vitro Test of Mycelial Growth Inhibition of 5 Fungi Pathogenic to Strawberries by Ultraviolet-C (UV-C) Irradiation

In strawberry production, among others, the high incidence of diseases by pathogenic fungi resulting in the reduction of fruit yield and quality requires the development of eco-friendly management systems rather than chemical sprays to control them. The diameter of colonies grown in media at 25 o C for 5 days was measured to evaluate the in vitro inhibition of mycelial growth of 5 pathogenic fungi by irradiation with ultraviolet (UV-C, 264 nm). The mycelial growth of 5 pathogenic fungi was inhibited in potato dextrose agar (PDA) by the irradiation of UV-C for 1 hour a day, and was dramatically inhibited by the irradiation of UV-C for 9-12 h a day. The irradiation of UV-C for 9-12 h a day inhibited completely the growth of the late blight pathogen, Phytophthora cactorum. The irradiation distance of 40 to 50 cm was effective for the inhibition of mycelial growth of fungi. The mycelial growth of fungi without pre-incubation was inhibited strongly by UV-C irradiation compared to fungi pre-incubated for 2 days without light. The mycelia growth of Colletotrichum gloeosprioides and Fusarium oxysporum was inhibited strongly by UV-C irradiation in vegetable 8 juice agar compared to PDA.

Transcriptomic changes in dormant buds of two grapevine cultivars following exposure to freezing temperature

In this study, transcriptomes of buds from two grapevine (Vitis labruscana) cultivars, moderately cold-tolerant ‘Campbell Early’ and cold-susceptible ‘Muscat Baily A’, exposed to freezing temperatures were analyzed to identify genes involved in cold hardiness. Selected differentially expressed genes (DEGs) were evaluated for their expression patterns and transcripts obtained from next generation sequencing were analyzed for their gene ontologies. We assembled ~100 million high-quality trimmed reads, and the functional categorization of transcripts induced by freezing revealed the differential regulation of genes involved in cellular processes, metabolic processes, and cellular metabolic process in ‘Campbell Early’ and ‘Muscat Baily A’ grapes. The most upregulated genes in ‘Campbell Early’ included those encoding a chalcone and stilbene synthase family protein, a RmlC-like cupin superfamily protein, a homolog of carrot EP3-3 chitinase, and a cytochrome P450. The most downregulated genes in the cold-sensitive ‘Muscat Baily A’ included those encoding a 17.6 kDa class II heat shock protein, a HXXXD-type acyl-transferase family protein, and GIBBERELLIN 2-OXIDASE 8. All major DEGs identified by the transcriptomic analysis were confirmed to be differentially expressed using real-time PCR. A protein domain analysis using UniprotKB revealed that non-specific serine/threonine protein kinase, nitrilase and cyanoalanine nitrilase were upregulated in both grapevine cultivars. The transcriptome profile of dormant buds exposed to freezing can provide valuable molecular information about the tolerance of grapevines to extremely low temperatures during winter.

Transcriptomic analysis of ‘Campbell Early’ and ‘Muscat Bailey A’ grapevine shoots exposed to freezing cold stress

To understand the responses of grapevines in response to cold stress causing the limited growth and development, differentially expressed genes (DEGs) were screened through transcriptome analysis of shoots from 2 grapevine cultivars (`Campbell Early` and `Muscat Baily A`) kept at - for 4 days. In gene ontology analysis of DEGs from `Campbell Early`, there were 17,424 clones related with biological process, 28,954 with cellular component, and 6,972 with molecular function genes in response to freezing temperature. The major induced genes included dehydrin xero 1, K-box region and MADS-box transcription factor family protein, and MYB domain protein 36, and inhibited genes included light-harvesting chlorophyll B-binding protein 3, FASCICLIN-like arabinoogalactan 9, and pectin methylesterase 61 in `Campbell Early` grapevines. In gene ontology analysis of DEGs from `Muscat Baily A`, there were 1,157 clones related with biological process, 1,350 with cellular component, and 431 with molecular function gene. The major induced genes of `Muscat Baily A` included NB-ARC domain-containing disease resistance protein, fatty acid hydrozylase superfamily, and isopentenyltransferase 3, and inhibited genes included binding, IAP-like protein 1, and pentatricopeptide repeat superfamily protein. All major DEGs were shown to be expressed differentially by freezing temperature in real time-PCR analysis. Protein domain analysis using InterPro Scan revealed that ubiquitin-protein ligase was redundant in both tested grapevines. Transcriptome profile of shoots exposed to cold can provide new insights into the molecular basis of tolerance to low-temperature in grapevines, and can be used as resources for development new grapevines tolerant to coldness.