Soon Young Ahn

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.

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.