• Soo-Chul Park

      Articles written in Journal of Biosciences

    • Expression profiles of hot pepper (capsicum annuum) genes under cold stress conditions

      Eul-Won Hwang Kyung-A Kim Soo-Chul Park Mi-Jeong Jeong Myung-Ok Byun Hawk-Bin Kwon

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      In an attempt to determine a cold defense mechanism in plants, we have attempted to characterize changes occurringin the expression of cold-regulated transcript levels in the hot pepper (Capsicum annuum), using cDNA microarray analysis, combined with Northern blot analysis. After analysing a 3.1 K hot pepper cDNA microarray, we isolated a total of 317 cold inducible genes. We selected 42 genes which were up-regulated and three genes which were down-regulated due to cold treatment, for further analysis. Among the 45 genes which appeared to be upregulated by cold, 19 genes appeared to be simultaneously regulated by salt stress. Among the up-regulated cold-stress genes, we identified a variety of transcription factors, including: a family of 4 ethylene-responsive element binding protein (EREBP, designated CaEREBP-C1 to C4) genes, a bZIP protein (CaBZ1), RVA1, Ring domain protein, HSF1, and the WRKY (CaWRKY1) protein. As mentioned earlier, several genes appeared to be induced not only by cold stress, but also simultaneously by salt stress. These genes included: CaEREBP-C3, CaBZ1, putativetrans-activator factor, NtPRp27, malate dehydrogenase, putative auxin-repressed protein, protein phosphatase (CaTPP1), SAR8.2 protein precursor, late-embryogenesis abundant protein 5 (LEA5), DNAJ protein homologue, xyloglucanendo-l,4-Β-D-gucanase precursor, PR10, and the putative non-specific lipid transfer protein StnsLTP.

    • Pleurotus sajor-caju HSP100 complements a thermotolerance defect inhsp104 mutantSaccharomyces cerevisiae

      Jin-Ohk Lee Mi-Jeong Jeong Tack-Ryun Kwon Seung-Kon Lee Myung-Ok Byun Ill-Min Chung Soo-Chul Park

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      A putativeHsp100 gene was cloned from the fungusPleurotus sajor-caju. mRNA expression studies demonstrated that this gene (designatedPsHsp100) is highly induced by high temperature, induced less strongly by exposure to ethanol, and not induced by drought or salinity. Heat shock induction is detectable at 37‡C and reaches a maximum level at 42‡C.PsHsp100 mRNA levels sharply increased within 15 min of exposure to high temperature, and reached a maximum expression level at 2 h that was maintained for several hours. These results indicate that PsHsp100 could work at an early step in thermotolerance. To examine its function,PsHsp100 was transformed into a temperature-sensitivehsp104 deletion mutantSaccharomyces cerevisiae strain to test the hypothesis that PsHSP100 is an protein that functions in thermotolerance. Overexpression of PsHSP100 complemented the thermotolerance defect of thehsp104 mutant yeast, allowing them survive even at 50‡C for 4 h. These results indicate that PsHSP100 protein is functional as an HSP100 in yeast and could play an important role in thermotolerance inP. sajor-caju.

    • Pleurotus sajor-caju HSP100 complements a thermotolerance defect inhsp104 mutantSaccharomyces cerevisiae

      Jin-Ohk Lee Mi-Jeong Jeong Tack-Ryun Kwon Seung-Kon Lee Myung-Ok Byun Ill-Min Chung Soo-Chul Park

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    • Erratum

      Jin-Ohk Lee Mi-Jeong Jeong Tack-Ryun Kwon Seung-Kon Lee Myung-Ok Byun Ill-Min Chung Soo-Chul Park

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    • Overexpression of the mitogen-activated protein kinase gene OsMAPK33 enhances sensitivity to salt stress in rice (Oryza sativa L.)

      Seong-Kon Lee Beom-Gi Kim Taek-Ryoun Kwon Mi-Jeong Jeong Sang-Ryeol Park Jung-Won Lee Myung-Ok Byun Hawk-Bin Kwon Benjamin F Matthews Choo-Bong Hong Soo-Chul Park

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      Mitogen-activated protein kinases (MAPK) signalling cascades are activated by extracellular stimuli such as environmental stresses and pathogens in higher eukaryotic plants. To know more about MAPK signalling in plants, a MAPK cDNA clone, OsMAPK33, was isolated from rice. The gene is mainly induced by drought stress. In phylogenetic analysis, OsMAPK33 (Os02g0148100) showed approximately 47–93% identity at the amino acid level with other plant MAPKs. It was found to exhibit organ-specific expression with relatively higher expression in leaves as compared with roots or stems, and to exist as a single copy in the rice genome. To investigate the biological functions of OsMAPK33 in rice MAPK signalling, transgenic rice plants that either overexpressed or suppressed OsMAPK33 were made. Under dehydration conditions, the suppressed lines showed lower osmotic potential compared with that of wild-type plants, suggesting a role of OsMAPK33 in osmotic homeostasis. Nonetheless, the suppressed lines did not display any significant difference in drought tolerance compared with their wild-type plants. With increased salinity, there was still no difference in salt tolerance between OsMAPK33-suppressed lines and their wild-type plants. However, the overexpressing lines showed greater reduction in biomass accumulation and higher sodium uptake into cells, resulting in a lower K+/Na+ ratio inside the cell than that in the wild-type plants and OsMAPK33-suppressed lines. These results suggest that OsMAPK33 could play a negative role in salt tolerance through unfavourable ion homeostasis. Gene expression profiling of OsMAPK33 transgenic lines through rice DNA chip analysis showed that OsMAPK33 altered expression of genes involved in ion transport. Further characterization of downstream components will elucidate various biological functions of this novel rice MAPK.

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