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ABSTRACT: Rice brown leaf spot is a major disease in the rice paddy field. The causal agent Cochliobolus miyabeanus is an ascomycete fungus and a representative necrotrophic pathogen in the investigation of rice-microbe interactions. The aims of this research were to identify a quantitative evaluation method to determine the amount of C. miyabeanus proliferation in planta and determine the method's sensitivity. Real-time polymerase chain reaction (PCR) was employed in combination with the primer pair and Taqman probe specific to CmSCD1, a C. miyabeanus unigene encoding SCYTALONE DEHYDRATASE, which is involved in fungal melanin biosynthesis. Comparative analysis of the nucleotide sequences of CmSCD1 from Korean strains with those from the Japanese and Taiwanese strains revealed some sequence differences. Based on the crossing point (CP) values from Taqman real-time PCR containing a series of increasing concentrations of cloned amplicon or fungal genomic DNA, linear regressions with a high level of reliability (R(2)>0.997) were constructed. This system was able to estimate fungal genomic DNA at the picogram level. The reliability of this equation was further confirmed using DNA samples from both resistant and susceptible cultivars infected with C. miyabeanus. In summary, our quantitative system is a powerful alternative in brown leaf spot forecasting and in the consistent evaluation of disease progression.
The Journal of Microbiology 12/2012; 50(6):947-54. · 1.10 Impact Factor
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ABSTRACT: Two strains of necrotrophic Alternaria brassicicola, Ab40857 and Ab42464, are virulent on Korean cabbage and several wild types of Arabidopsis thaliana. Interaction between Ab42464 and Col-0 was compatible, whereas interaction between Ab40857 and Col-0 was incompatible. The
loss of defense, no death (dnd) 1 function abrogated the compatibility between Ab42464 and Col-0, and the accelerated cell death (acd) 2 mutation attenuated the Col-0’s resistance against Ab40857. These two fungal strains induced PR1 transcription in Col-0. Ab40857 accelerated transcription of PDF1.2, THI2.1, CAT, and POX by 12 h compared to those challenged with Ab42464. More abundant cell death was observed in Col-0 infected with Ab42464,
however, callose deposition was evident in the incompatible interaction. Remarkably, Ab40857-infected areas of acd2-2 underwent rampant cell death and Ab42464 triggered callose production in dnd1-1. Furthermore, the incompatibility between Ab40857 and Col-0 was nullified by the coronatine-insensitive 1 (coi1) and phytoalexin-deficient 3 (pad3) mutations but not by nonexpresser of PR genes (npr1) and pad4. Ab40857 induced abundant cell death in pad3. Taken together, cell death during the early infection stage is a key determinant that discriminates between a compatible
interaction and an incompatible one, and the resistance within Col-0 against Ab40857 is dependent on a defense-signaling pathway
mediated by jasmonic acid and PAD3.
Keywordsnecrotroph–programmed cell death
Molecules and Cells 04/2012; 31(6):593-601. · 2.18 Impact Factor
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ABSTRACT: A selected strain of rhizobacterium, Pseudomonas putida strain LSW17S (LSW17S), protects tomato plants (Lycopersicon esculentum L. cv. Seokwang) from bacterial speck by biotrophic Pseudomonas syringae pv. tomato strain DC3000 (DC3000) and bacterial wilt by necrotrophic Ralstonia solanacearum KACC 10703 (Rs10703). To investigate defense mechanisms induced by LSW17S in tomato plants, transcription patterns of pathogenesis-related (PR) genes and H(2)O(2) production were analyzed in plants treated with LSW17S and subsequent pathogen inoculation. LSW17S alone did not induce transcriptions of employed PR genes in leaves and roots. DC3000 challenge following LSW17S triggered rapid transcriptions of PR genes and H(2)O(2) production in leaves and roots. Catalase infiltration with DC3000 attenuated defense-related responses and resistance against DC3000 infection. Despite depriving H(2)O(2) production and PR1b transcription by the same treatment, resistance against Rs10703 infection was not deterred significantly. H(2)O(2) is indispensable for defense signaling and/or mechanisms primed by LSW17S and inhibition of bacterial speck, however, it is not involved in resistance against bacterial wilt.
Molecules and Cells 06/2011; 32(1):7-14. · 2.18 Impact Factor
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ABSTRACT: Two strains of necrotrophic Alternaria brassicicola, Ab40857 and Ab42464, are virulent on Korean cabbage and several wild types of Arabidopsis thaliana. Interaction between Ab42464 and Col-0 was compatible, whereas interaction between Ab40857 and Col-0 was incompatible. The loss of defense, no death (dnd) 1 function abrogated the compatibility between Ab42464 and Col-0, and the accelerated cell death (acd) 2 mutation attenuated the Col-0's resistance against Ab40857. These two fungal strains induced PR1 transcription in Col-0. Ab40857 accelerated transcription of PDF1.2, THI2.1, CAT, and POX by 12 h compared to those challenged with Ab42464. More abundant cell death was observed in Col-0 infected with Ab42464, however, callose deposition was evident in the incompatible interaction. Remarkably, Ab40857-infected areas of acd2-2 underwent rampant cell death and Ab42464 triggered callose production in dnd1-1. Furthermore, the incompatibility between Ab40857 and Col-0 was nullified by the coronatine-insensitive 1 (coi1) and phytoalexin-deficient 3 (pad3) mutations but not by nonexpresser of PR genes (npr1) and pad4. Ab40857 induced abundant cell death in pad3. Taken together, cell death during the early infection stage is a key determinant that discriminates between a compatible interaction and an incompatible one, and the resistance within Col-0 against Ab40857 is dependent on a defense-signaling pathway mediated by jasmonic acid and PAD3.
Molecules and Cells 06/2011; 31(6):593-601. · 2.18 Impact Factor
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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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ABSTRACT: 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, aMAPK 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.
Journal of Biosciences 03/2011; 36(1):139-51. · 1.65 Impact Factor
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Dongjin Shin,
Seok-Jun Moon,
Seyoun Han,
Beom-Gi Kim, Sang Ryeol Park,
Seong-Kon Lee,
Hye-Jin Yoon,
Hye Eun Lee,
Hawk-Bin Kwon,
Dongwon Baek,
Bu Young Yi,
Myung-Ok Byun
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ABSTRACT: Potato (Solanum tuberosum) is relatively vulnerable to abiotic stress conditions such as drought, but the tolerance mechanisms for such stresses in potato are largely unknown. To identify stress-related factors in potato, we previously carried out a genetic screen of potato plants exposed to abiotic environmental stress conditions using reverse northern-blot analysis. A cDNA encoding a putative R1-type MYB-like transcription factor (StMYB1R-1) was identified as a putative stress-response gene. Here, the transcript levels of StMYB1R-1 were enhanced in response to several environmental stresses in addition to drought but were unaffected by biotic stresses. The results of intracellular targeting and quadruple 9-mer protein-binding microarray analysis indicated that StMYB1R-1 localizes to the nucleus and binds to the DNA sequence (G)/(A)GATAA. Overexpression of a StMYB1R-1 transgene in potato plants improved plant tolerance to drought stress while having no significant effects on other agricultural traits. Transgenic plants exhibited reduced rates of water loss and more rapid stomatal closing than wild-type plants under drought stress conditions. In addition, overexpression of StMYB1R-1 enhanced the expression of drought-regulated genes such as AtHB-7, RD28, ALDH22a1, and ERD1-like. Thus, the expression of StMYB1R-1 in potato enhanced drought tolerance via regulation of water loss. These results indicated that StMYB1R-1 functions as a transcription factor involved in the activation of drought-related genes.
Plant physiology 10/2010; 155(1):421-32. · 6.53 Impact Factor
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Hye Eun Lee,
Dongjin Shin, Sang Ryeol Park,
Sang-Eun Han,
Mi-Jeong Jeong,
Tack-Ryun Kwon,
Seong-Kon Lee,
Soo-Chul Park,
Bu Young Yi,
Hawk-Bin Kwon,
Myung-Ok Byun
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ABSTRACT: To identify components of the plant stress signal transduction cascade and response mechanisms, we screened plant genes using reverse Northern blot analysis, and chose the ethylene responsive element binding protein 1 (StEREBP1) for further characterization. To investigate its biological function in the potato, we performed Northern blot analysis and observed enhanced levels of transcription in response to several environmental stresses including low temperature. In vivo targeting experiments using a green fluorescent protein (GFP) reporter indicated that StEREBP1 localized to the nucleus of onion epidermal cells. StEREBP1 was found to bind to GCC and DRE/CRT cis-elements and both microarray and RT-PCR analyses indicated that overexpression of StEREBP1 induced expression of several GCC box-containing stress response genes. In addition, overexpression of StEREBP1 enhanced tolerance to cold and salt stress in transgenic potato plants. The results of this study suggest that StEREBP1 is a functional transcription factor that may be involved in abiotic stress responses in plants.
Biochemical and Biophysical Research Communications 03/2007; 353(4):863-8. · 2.48 Impact Factor
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ABSTRACT: This study generated transgenic tobacco plants expressing trehalose phosphorylase of Pleurotus sajor-caju (PsTP) constitutively under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Sixteen transgenic lines were selected by genomic Southern blot analysis for further study. Unlike yeast TPS1-transformed or Escherichia coli TPS1-transformed tobacco or potato, all of the PsTP transgenic tobacco lines showed normal growth phenotypes both in the culture tubes and soil mixture. The study measured the trehalose contents of PsTP-transformed tobacco plants as well as the wild type and empty vector-transformed control plants. Results showed that the PsTP transformant contained 6.3molg–1 of plant tissues, while the wild type and the control plants had only minimal levels of trehalose. Because this study detected a significant amount of trehalose in PsTP transgenic tobacco plants, it decided to carry out a bioanalysis of the PsTP transgenic tobacco plants by drought treatment by not watering the plants for over 10days. A significant difference in drought resistance was observed from the second nonwatering day between the transgenic and the control tobacco plants. The transgenic tobacco plants had normal growth and did not wither, while the wild type and the only empty vector-transformed control plants withered severely. Among all the transgenic lines, line 10-4 showed the strongest resistance to drought stress. It did not wither even after 10days without watering. In addition, when the drought resistance of PsTP transgenic tobacco plants was tested using detached leaves, most transgenic plants, except one line, showed better capacity to retain water than the empty vector-transformed transgenic plant.
Plant Cell Tissue and Organ Culture 07/2005; 82(2):151-158. · 3.09 Impact Factor
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ABSTRACT: Salt stress is a major environmental factor influencing plant growth and development and plants have many tolerance mechanisms to overcome salt stress. To identify salt tolerance determinants in higher plants, an Arabidopsis cDNA clone that encodes translation elongation factor 1 alpha (AtEF1α) was isolated by functional complementation of the salt-sensitive phenotype of a calcineurin (CaN)-deficient yeast mutant (cnbΔ). AtEF1α displayed a chaperone activity in a dose-dependant manner in vitro and the chaperone activity of AtEF1α was required for NaCl tolerance in cnbΔ cells. When compared with wild-type Arabidopsis, AtEF1α knock-out plants were more sensitive to NaCl stress. Furthermore, transgenic plants with transgene AtEF1α were more tolerant to NaCl than the wild-type. These results suggest that AtEF1α functions as molecular chaperone, and this activity enhances NaCl tolerance in yeast and plants.
Plant Science.
