Biomedical subjects

Ryoung Shin

Publications and source records attributed to Ryoung Shin.

14 recordsLinked to original sources

PubMed2007

Nutrient sensing and signaling: NPKS.

Plants often grow in soils that contain very low concentrations of the macronutrients nitrogen, phosphorus, potassium, and sulfur. To adapt and grow in nutrient-deprived environments plants must sense changes in external and internal mineral nutrient concentrations and adjust growth to match resource availability. The sensing and signal transduction networks that control plant responses to nutrient deprivation are not well characterized for nitrogen, potassium, and sulfur deprivation. One branch of the signal transduction cascade related to phosphorus-deprivation response has been defined through the identification of a transcription factor that is regulated by sumoylation. Two different microRNAs play roles in regulating gene expression under phosphorus and sulfur deprivation. Reactive oxygen species increase rapidly after mineral nutrient deprivation and may be one upstream mediator of nutrient signaling. A number of molecular analyses suggest that both short-term and longer-term responses will be important in understanding the progression of signaling events when the external, then internal, supplies of nutrients become depleted.

Adaptation, Physiological↗

PubMed2006

Transporters expressed during grape berry (Vitis vinifera L.) development are associated with an increase in berry size and berry potassium accumulation.

Potassium accumulation is essential for grapevine (Vitis vinifera L.) growth and development, but excessive levels in berries at harvest may reduce wine quality particularly for red wines. In addition to decreasing the free acid levels, potassium also combines with tartaric acid to form largely insoluble potassium bitartrate. This precipitates during winemaking and storage, resulting in an increase in wine pH that is associated with negative impacts on wine colour, flavour, and microbiological stability. For these reasons, a better understanding of potassium transport and accumulation within the vine and berries is important for producing fruit with improved winemaking characteristics. Here two genes encoding KUP/KT/HAK-type potassium transporters that are expressed in grape berries are described. Their function as potassium transporters was demonstrated by complementation of an Escherichia coli mutant. The two transporters are expressed most highly in the berry skin during the first phase of berry development (pre-veraison), with similar patterns in two grapevine varieties. The timing and location of expression of these transporters are consistent with an involvement in potassium accumulation in grape berries.

Blotting, Southern↗

PubMed2005

Reactive oxygen species and root hairs in Arabidopsis root response to nitrogen, phosphorus and potassium deficiency.

Plant root sensing and adaptation to changes in the nutrient status of soils is vital for long-term productivity and growth. Reactive oxygen species (ROS) have been shown to play a role in root response to potassium deprivation. To determine the role of ROS in plant response to nitrogen and phosphorus deficiency, studies were conducted using wild-type Arabidopsis and several root hair mutants. The expression of several nutrient-responsive genes was determined by Northern blot, and ROS were quantified and localized in roots. The monitored genes varied in intensity and timing of expression depending on which nutrient was deficient. In response to nutrient deprivation, ROS concentrations increased in specific regions of the Arabidopsis root. Changes in ROS localization in Arabidopsis and in a set of root hair mutants suggest that the root hair cells are important for response to nitrogen and potassium. In contrast, the response to phosphorus deprivation occurs in the cortex where an increase in ROS was measured. Based on these results, we put forward the hypothesis that root hair cells in Arabidopsis contain a sensing system for nitrogen and potassium deprivation.

Arabidopsis↗

PubMed2004

Hydrogen peroxide mediates plant root cell response to nutrient deprivation.

Potassium (K(+)) is an essential nutrient required by plants in large quantities, but changes in soil concentrations may limit K(+) acquisition by roots. It is not known how plant root cells sense or signal the changes that occur after the onset of K(+) deficiency. Changes in the kinetics of Rb(+) uptake in Arabidopsis roots occur within 6 h after K(+) deprivation. Reactive oxygen species (ROS) and ethylene increased when the plants were deprived of K(+). ROS accumulated in a discrete region of roots that has been shown to be active in K(+) uptake and translocation. Suppression of an NADPH oxidase in Arabidopsis (rhd2), which is involved in ROS production, prevented the up-regulation of genes that are normally induced by K(+) deficiency, but the induction of high-affinity K(+) transport activity was unchanged. Application of H(2)O(2) restored the expression of genes induced by K(+) deficiency in rhd2 and was also sufficient to induce high-affinity K(+) transport activity in roots grown under K(+)-sufficient conditions. ROS production is an early root response to K(+) deficiency that modulates gene expression and physiological changes in the kinetics of K(+) uptake.

Arabidopsis↗

PubMed2004

Capsicum annuum tobacco mosaic virus-induced clone 1 expression perturbation alters the plant's response to ethylene and interferes with the redox homeostasis.

Capsicum annuum tobacco mosaic virus (TMV)-induced clone 1 (CaTin1) gene was expressed early during incompatible interaction of hot pepper (Caspsicum annuum) plants with TMV and Xanthomonas campestris. RNA-blot analysis showed that CaTin1 gene was expressed only in roots in untreated plants and induced mainly in leaf in response to ethylene, NaCl, and methyl viologen but not by salicylic acid and methyl jasmonate. The ethylene dependence of CaTin1 induction upon TMV inoculation was demonstrated by the decrease of CaTin1 expression in response to several inhibitors of ethylene biosynthesis or its action. Transgenic tobacco (Nicotiana tabacum) plants expressing CaTin1 gene in sense- or antisense-orientation showed interesting characteristics such as the accelerated growth and the enhanced resistance to biotic as well as abiotic stresses. Such characteristics appear to be caused by the elevated level of ethylene and H2O2. Moreover, in transgenic plants expressing antisense CaTin1 gene, the expression of some pathogenesis-related genes was enhanced constitutively, which may be mainly due to the increased ethylene level. The promoter of CaTin1 has four GCC-boxes, two AT-rich regions, and an elicitor-inducible W-box. The induction of the promoter activity by ethylene depends on GCC-boxes and by TMV on W-box. Taken together, we propose that the CaTin1 up-regulation or down-regulation interferes with the redox balance of plants leading to the altered response to ethylene and biotic as well as abiotic stresses.

Acetates↗

PubMed2004

Expression of KT/KUP genes in Arabidopsis and the role of root hairs in K+ uptake.

Potassium (K(+)) is the most abundant cation in plants and is required for plant growth. To ensure an adequate supply of K(+), plants have multiple mechanisms for uptake and translocation. However, relatively little is known about the physiological role of proteins encoded by a family of 13 genes, named AtKT/KUP, that are involved in K(+) transport and translocation. To begin to understand where and under what conditions these transporters function, we used reverse transcription-PCR to determine the spatial and temporal expression patterns of each AtKT/KUP gene across a range of organs and tested whether selected AtKT/KUP cDNAs function as K(+) transporters in Escherichia coli. Many AtKT/KUPs were expressed in roots, leaves, siliques, and flowers of plants grown under K(+)-sufficient conditions (1.75 mm KCl) in hydroponic culture. AtHAK5 was the only gene in this family that was up-regulated upon K(+) deprivation and rapidly down-regulated with resupply of K(+). Ten AtKT/KUPs were expressed in root hairs, but only five were expressed in root tip cells. This suggests an important role for root hairs in K(+) uptake. The growth and rubidium (Rb(+)) uptake of two root hair mutants, trh1-1 (tiny root hairs) and rhd6 (root hair defective), were studied to determine the contribution of root hairs to whole-plant K(+) status. Whole-plant biomass decreased in the root hair mutants only when K(+) concentrations were low; Rb(+) (used as a tracer for K(+)) uptake rates were lower in the mutants at all Rb(+) concentrations. Seven genes encoding AtKUP transporters were expressed in E. coli (AtKT3/KUP4, AtKT/KUP5, AtKT/KUP6, AtKT/KUP7, AtKT/KUP10, AtKT/KUP11, and AtHAK5), and their K(+) transport function was demonstrated.

Arabidopsis↗

PubMed2004

Pathogenesis-related protein 10 isolated from hot pepper functions as a ribonuclease in an antiviral pathway.

A hot pepper (Capsicum annuum) cDNA clone encoding pathogenesis-related protein 10 (CaPR-10) was isolated by differential screening of a cDNA library prepared from pepper leaves inoculated with tobacco mosaic virus pathotype (TMV-P0). CaPR-10 transcripts were induced in the incompatible interaction with TMV-P0 or Xanthomonas campestris pv. vesicatoria (Xcv) but not induced in the compatible interaction. Characterization of enzymatic properties of CaPR-10 indicated that the recombinant protein exhibits a ribonucleolytic activity against TMV RNA, as well as against pepper total RNA, and shows its putative antiviral activity in several conditions. The CaPR-10 protein existed at very low level in leaf tissue but was dramatically induced as soon as plants were inoculated with TMV-P0, and this was correlated with the increase of its ribonucleolytic activity. Immunoblot analysis and pull-down assays using proteins extracted from pepper leaves showed that TMV-P0 inoculation led to the phosphorylation of CaPR-10, a modification that should affect its capacity for RNase function. We present data that the induction and subsequent phosphorylation of CaPR-10 increased its ribonucleolytic activity to cleave invading viral RNAs, and this activity should be important to its antiviral pathway during viral attack in vivo.

Amino Acid Sequence↗

PubMed2003

A novel TMV-induced hot pepper cell wall protein gene (CaTin2) is associated with virus-specific hypersensitive response pathway.

Incompatible plant-pathogen interactions result in the rapid cell death response known as hypersensitive response (HR) and activation of host defense related genes. To understand the cellular mechanism controlling defense response better, a novel pathogenesis-related (PR) gene and putative cell wall protein gene, CaTin2, was isolated through differential screening of a hot pepper cDNA library and characterized. CaTin2 gene was locally and systemically induced in hot pepper plants upon TMV-P0 inoculation which induces HR. However, CaTin2 gene wasn't regulated by bacterial HR-specific signal pathway. The full-length cDNA for CaTin2, which is 864 nucleotides long, contained the open reading frame of 200 amino acids including cell wall targeting sequences of 26 amino acids. CaTin2 gene has no sequence similarity with other cell wall protein genes except the signal sequence and exists as only one copy in hot pepper genome. CaTin2 gene contains repeated helix-turn-helix motif consisting of 39 amino acids. CaTin2 mRNA accumulation was induced in response to various treatments such as ethylene, SA, MeJA, ABA, methyl viologen, NaCl and wounding at early time points. Subcelluar localization of CaTin2 was confirmed in the cell wall in hot pepper leaves by making CaTin2::smGFP fusion protein. The transgenic plants overexpressing CaTin2 cDNA were resistant to TMV and CMV inoculation. From these results, CaTin2 gene may encode a virus-related new cell wall protein member.

Abscisic Acid↗

PubMed2003

The CaTin1 (Capsicum annuum TMV-induced clone 1) and CaTin1-2 genes are linked head-to-head and share a bidirectional promoter.

CaTin1 was expressed relatively early in the TMV-inoculated leaves of hot pepper which is resistant to TMV-P(0) infection. Interestingly, there was another homologous gene (CaTin1-2) located in front of CaTin1 in a head-to-head fashion and they shared a single promoter. The expression profile of the CaTin1-2 was very similar to CaTin1 in all the treatments except the slower induction time compared to CaTin1 upon TMV-P(0) inoculation. The promoter analysis of CaTin1 and CaTin1-2 revealed bidirectionality both in cis-elements and activity. The CaTin1-2 promoter had two TATA-boxes, four GCC-boxes, the root responsive element, and a W1-box. The ethylene-inducible promoter activity depended on GCC-boxes and TMV-inducible activity of the CaTin1-2 promoter reached its highest activity when this promoter had a W1-box.

Amino Acid Sequence↗

PubMed2003

Differential metal selectivity and gene expression of two zinc transporters from rice.

Zinc is an essential mineral for a wide variety of physiological and biochemical processes. To understand zinc transport in cereals, we identified putative zinc transporters in gene databases. Three full-length cDNAs were identified and characterized from rice (Oryza sativa). Two of the cDNAs partially complemented a yeast (Saccharomyces cerevisiae) mutant deficient in zinc uptake at low concentrations. The two transporters showed many similarities in function but differed in ionic selectivity and pH optimum of activity. Expression patterns also differed between the two genes. One gene was broadly expressed under all conditions, and the other gene was mainly induced by zinc deficiency to higher levels in roots than in leaves. Although the timing of expression differed between the two genes, localization of expression overlapped in roots. Comparisons of the protein sequences, ionic selectivity, and gene expression patterns of the two transporters suggest that they may play different roles in the physiology of the whole plant.

Amino Acid Sequence↗

PubMed2002

A hot pepper cDNA encoding ascorbate peroxidase is induced during the incompatible interaction with virus and bacteria.

Capsicum annuum L. is infected by a number of viruses, including the tobacco mosaic virus (TMV). To study the defense-related genes that are induced by TMV in hot peppers, the pepper plant, which is susceptible to P1.2 but resistant to the P0 pathotype of TMV, was inoculated with TMV-P0. Differential screening isolated the genes that were specifically up- or down-regulated during the hypersensitive response (HR). The CaAPX1 cDNA clone that putatively encodes a polypeptide of cytosolic ascorbate peroxidase was selected as an up-regulated gene. It was isolated for further study. The full-length cDNA for CaAPX1, which is 972 bp long, contained the open-reading frame of 250-amino acid residues. A genomic Southern blot analysis showed that there were only limited copies of the CaAPX1 gene in the hot pepper genome. In hot pepper cv. Bugang, which is resistant to TMV-P0 and susceptible to TMV-P1.2, the CaAPX1 gene transcript was accumulated by TMV-P0, but not by TMV-P1.2 inoculation. CaAPX1 transcripts began to accumulate 24 h post-inoculation of TMV-P0, and increased gradually until 96 h. To investigate whether each transcript is induced by other stimuli, the plants were treated with various chemicals and wounding. A striking induction of the CaAPX1 transcript was observed at 2 h. It subsided 12 h after salicylic acid (SA), ethephon, and methyl jasmonate (MeJA) treatments. The response of the gene upon other pathogen infection was also examined by a bacterial pathogen (Xanthomonas campestris pv. vesicatoria race 3) inoculation. The CaAPX1 gene was induced in a hot pepper (C. annuum cv. ECW 20R) that was resistant to this bacterial pathogen, but not in a susceptible hot pepper (C. annuum cv. ECW). These results suggest the possible role(s) for the CaAPX1 gene in plant defense against viral and bacterial pathogen.

Amino Acid Sequence↗

PubMed2002

Induction of pepper cDNA encoding a lipid transfer protein during the resistance response to tobacco mosaic virus.

Pepper (Capsicum annuum) plants exhibit hypersensitive response (HR) against infection by many tobamoviruses. A clone encoding a putative nonspecific lipid transfer protein (CaLTP1) was isolated by differential screening of a cDNA library from resistant pepper leaves when inoculated with tobacco mosaic virus (TMV) pathotype P0. The predicted amino acid sequence of CaLTP1 is highly similar to that of the other plant LTPs. Southern blot analysis showed that a small gene family of LTP-related sequences was present in the pepper genome. Transcripts homologous to CaLTP1 accumulated abundantly in old leaves and flowers. CaLTP1 expression was induced in the incompatible interaction with TMV-P0 but was not induced in the compatible interaction with TMV-P1.2. In correlation with the temporal progression of HR in the inoculated leaves, CaLTP1 transcripts started to accumulate at 24 h after TMV-P0 inoculation, reaching a maximal level at 48 h. A strain of Xanthomonas campestris pv. vesicatoria (Xcv) that carries the bacterial avirulence gene, avrBs2, was infiltrated into leaves of a pepper cultivar containing the Bs2 resistance gene. A marked induction of CaLTP1 expression was observed in Xcv-infiltrated leaves. Effects of exogenously applied abiotic elicitors on CaLTP1 expression were also examined. Salicylic acid caused a rapid accumulation of CaLTP1 transcripts in pepper leaves and ethephon treatment also induced the expression of the CaLTP1 gene. Transient expression in the detached pepper leaves by biolistic gene bombardment indicated that CaLTP1 is localized mostly at the plant cell surface, possibly in the cell wall. These results suggest possible role(s) for LTPs in plant defense against pathogens including viruses.

Amino Acid Sequence↗

PubMed2002

The potential use of a viral coat protein gene as a transgene screening marker and multiple virus resistance of pepper plants coexpressing coat proteins of cucumber mosaic virus and tomato mosaic virus.

Transgenic pepper plants coexpressing coat proteins (CPs) of cucumber mosaic virus (CMV-Kor) and tomato mosaic virus (ToMV) were produced by Agrobacterium-mediated transformation. To facilitate selection for positive transformants in transgenic peppers carrying an L gene, we developed a simple and effective screening procedure using hypersensitive response upon ToMV challenge inoculation. In this procedure, positive transformants could be clearly differentiated from the nontransformed plants. Transgenic pepper plants expressing the CP genes of both viruses were tested for resistance against CMV-Kor and pepper mild mottle virus (PMMV). In most transgenic plants, viral propagation was substantially retarded when compared to the nontransgenic plants. These experiments demonstrate that our transgenic pepper plants might be a useful marker system for the transgene screening and useful for classical breeding programs of developing virus resistant hot pepper plants.

Agrobacterium tumefaciens↗

PubMed2002

Ectopic expression of Tsi1 in transgenic hot pepper plants enhances host resistance to viral, bacterial, and oomycete pathogens.

In many plants, including hot pepper plants, productivity is greatly affected by pathogen attack. We reported previously that tobacco stress-induced gene 1 (Tsi1) may play an important role in regulating stress responsive genes and pathogenesis-related (PR) genes. In this study, we demonstrated that overexpression of Tsi1 gene in transgenic hot pepper plants induced constitutive expression of several PR genes in the absence of stress or pathogen treatment. The transgenic hot pepper plants expressing Tsi1 exhibited resistance to Pepper mild mottle virus (PMMV) and Cucumber mosaic virus (CMV). Furthermore, these transgenic plants showed increased resistance to a bacterial pathogen, Xanthomonas campestris pv. vesicatoria and also an oomycete pathogen, Phytophthora capsici. These results suggested that ectopic expression of Tsi1 in transgenic hot pepper plants enhanced the resistance of the plants to various pathogens, including viruses, bacteria, and oomycete. These results suggest that using transcriptional regulatory protein genes may contribute to developing broad-spectrum resistance in crop plants.

Bacteria↗