• The Plant Pathology Journal
• /
• v.27 no.2
• /
• pp.170-182
• /
• 2011

Plants possess multiple resistance mechanisms that protect themselves against pathogen attack. To identify unknown components of the defense machinery in Arabidopsis, gene-expression changes were monitored in Arabidopsis thaliana under 18 different biotic or abiotic conditions using a DNA microarray representing approximately 25% of all Arabidopsis thaliana genes (www.genevestigator.com). Seventeen genes which are early responsive to salicylic acid (SA) treatment as well as pathogen infection were selected and their T-DNA insertion mutants were obtained from SALK institute. To elucidate the role of each gene in defense response, bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000 was inoculated onto individual T-DNA insertion mutants. Four mutants exhibited decreased resistance and five mutants displayed significantly enhanced resistance against Pst DC3000-infection as measured by change in symptom development as compared to wild-type plants. Among them, member of uridin diphosphate (UDP)-glycosyltransferase (UGT) was of particular interest, since a UGT mutant (At1g05680) showed enhanced resistance to Pst-infection in Arabidopsis. In systemic acquired resistance (SAR) assay, this mutant showed enhanced activation of SAR. Also, the enhanced SAR correlated with increased expression of defense-related gene, AtPR1. These results emphasize that the glycosylation of UGT74E2 is a part of the SA-mediated disease-resistance mechanism.

• Molecules and Cells
• /
• v.46 no.11
• /
• pp.710-724
• /
• 2023

The plant defense responses to microbial infection are tightly regulated and integrated with the developmental program for optimal resources allocation. Notably, the defense-associated hormone salicylic acid (SA) acts as a promoter of flowering while several plant pathogens actively target the flowering signaling pathway to promote their virulence or dissemination. Ralstonia pseudosolanacearum inject tens of effectors in the host cells that collectively promote bacterial proliferation in plant tissues. Here, we characterized the function of the broadly conserved R. pseudosolanacearum effector RipL, through heterologous expression in Arabidopsis thaliana. RipL-expressing transgenic lines presented a delayed flowering, which correlated with a low expression of flowering regulator genes. Delayed flowering was also observed in Nicotiana benthamiana plants transiently expressing RipL. In parallel, RipL promoted plant susceptibility to virulent strains of Pseudomonas syringae in the effector-expressing lines or when delivered by the type III secretion system. Unexpectedly, SA accumulation and SA-dependent immune signaling were not significantly affected by RipL expression. Rather, the RNA-seq analysis of infected RipL-expressing lines revealed that the overall amplitude of the transcriptional response was dampened, suggesting that RipL could promote plant susceptibility in an SA-independent manner. Further elucidation of the molecular mechanisms underpinning RipL effect on flowering and immunity may reveal novel effector functions in host cells.

• Journal of Bio-Environment Control
• /
• v.28 no.2
• /
• pp.178-184
• /
• 2019

Strawberry ($Fragaria{\times}ananassa$) is one of the most important and popular fruit crops in the world, and 'Sulhyang' is one of the principal cultivars cultivated in the Republic of Korea for the domestic market. The growth and flower induction in strawberry is the process which influences directly on fruit bearing and yield of this crop. In this study, effect of benzyladenine (BA), gibberellic acid ($GA_3$), and salicylic acid (SA) on growth and flower bud induction in strawberry 'Sulhyang' was investigated. The 3-week-old runner plants, grown in 21-cell propagation trays, were potted and cultivated in growth chambers with $25^{\circ}C/15^{\circ}C$ (day/night) temperatures, 70% relative humidity (RH), and light intensity of $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux density (PPFD) provided by white light emitting diodes (LEDs). The runner plants were treated with one of three concentrations, 0 (control), 100, and $200mg{\cdot}L^{-1}$ of BA, $GA_3$, or SA solution. The chemicals were sprayed two times on leaves of runner plants at an interval of two weeks. After 9 weeks the results showed that the application of all chemicals caused reduction of root length and chlorophyll (SPAD) content as compared to the control. The lowest chlorophyll (SPAD) content was recorded in plants treated with $GA_3$. However, the treatment of $200mg{\cdot}L^{-1}$ $GA_3$ promoted leaf area, leaf fresh weight, and plant fresh weight. The greatest flower induction (85%) and number of inflorescences (4.3 inflorescences per plant) were observed in the treatment of $200mg{\cdot}L^{-1}\;SA$, followed by $100mg{\cdot}L^{-1}\;SA$. Overall, results suggest that foliar application of $GA_3$ solution could accelerate plant growth, while foliar application of SA solution could induce hastened flowering. Further studies may be needed to find out the relationship between $GA_3$ and SA solutions treated in a combination, and the molecular mechanism involved in those responses observed.

• Journal of Plant Biotechnology
• /
• v.42 no.1
• /
• pp.34-42
• /
• 2015

This study was conducted to investigate the productivity of biomass and antioxidant compounds in Polygonum multiflorum by culturing explants in air-lift bioreactor containing Murashige and Skoog (MS) medium, by adding different concentrations of auxins [indole-3-butyric acid (IBA) and naphthalene acetic acid (NAA)], sucrose, methyl jasmonate (MeJA), and salicylic acid (SA). Results of this study revealed that the explants culturing on the medium supplemented with $9.84{\mu}M$ IBA and 50 g/L sucrose were observed to have higher productivity of biomass and bioactive compound than other treatments used. Thus, we expect that these results will be helpful for large-scale production of biomass and antioxidant compounds from Polygonum multiflorum.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.287-287
• /
• 2022

In this study, we analyze RNA-seq data from OxF3Hand WT at several points (Oh, 3 h, 12 h, and 24 h) after WBPH infection. A number of the genes were further validated by RT-qPCR. Results revealed that highest number of DEGs (4,735) between the two genotypes detected after 24 h of infection. Interestingly, many of the DEGs between the WT and OsF3H under control conditions were also found to be differentially expressed in OsF3H in response to WBPH infestation. These results indicate that significant differences in gene expression between the "OxF3H" and "WT" exist as the infection time increases. Many of these DEGs were related to oxidoreductase activity, response to stress, salicylic acid biosynthesis, metabolic process, defense response to pathogen, cellular response to toxic substance, and regulation of hormones level. Moreover, genes involved in salicylic acid (SA) and Ethylene (Et) biosynthesis were upregulated in OxF3H plants while jasmonic acid (JA), Brassinosteroid (Br), and abscisic acid (ABA) signaling pathways were found downregulated in OxF3H plant during WBPH infestation. Interestingly, many DEGs related to pathogenesis such as OsPR1, OsPR1b, NPR1, OsNPR3 and OsNPR5 were found significantly upregulated in OxF3H plants. Additionally, genes related to MAPKs pathway, and about 30 WRKY genes involved in different pathways were found upregulated in OxF3H plants after WBPH infestation. This suggests that overexpression of the OxF3H gene leads to multiple transcriptomic changes and impact plant hormones, pathogenic related and secondary metabolites related genes and enhancing the plant resistance to WBPH infestation.

• Journal of Plant Biotechnology
• /
• v.45 no.4
• /
• pp.340-346
• /
• 2018

In this study, the effect of elicitors such as yeast extract (YE), methyl jasmonate (MeJA) and salicylic acid (SA) on the accumulation of eurycomanone in Eurycoma longifolia cell cultures were investigated. Suspension cells of E. longifolia was cultured in Murashige and Skoog (MS) medium supplemented with 30 g/L sucrose, 1.25 mg/L naphthaleneacetic acid (NAA) and 1 mg/L kinetin at a shaking speed of 120 rpm. Elicitors were added in the culture at different concentrations and times to stimulate eurycomanone accumulation in the Eurycoma longifolia cells. Eurycomanone content was determined by HPLC with a C18 column, flow rate of 0.8 mL/min, run time of 17.5 min, and a detector wavelength of 254 nm. The stationary phase was silica gel and the mobile phase was acetonitrile: $H_2O$. Non-elicited cells were used as the control. The study showed the effect of different elicitor concentrations, YE at 200 mg/L, MeJA at $20{\mu}M$ and SA at $20{\mu}M$ stimulated high production of eurycomanone. In which, treatment of $20{\mu}M$ MeJA after 4 days of culture resulted in the highest accumulation of this compound (17.36 mg/g dry weight), approximately 10-fold higher than that of untreated cells (1.70 mg/g dry weight).

• Journal of Plant Biotechnology
• /
• v.31 no.1
• /
• pp.83-88
• /
• 2004

Expression of an anionic peroxidase swpa2 gene isolated from cultured cells of sweetpotato (Ipomoea batatas) was investigated under various stress conditions by RT-PCR. The swpa2 gene was not expressed in any tissues of intact sweetpotato plant grown at the normal condition. The expression of this gene was strongly induced in leaf tissue by treatment of $H_2O$$_2$ (440mM). Treatment of NaCl (100mM), ABA (0.1mM) and methyl jasmonate(MeJA, 0.1mM) also induced the expression of swpa2 gene. Interestingly, salicylic acid (SA, 0.1 mM) did not induce the expression of swpa2 gene, indicating that anionic swpa2 POD is differently involved in SA and MeJA signaling pathways. In addition, swpa2 gene was strongly induced in sweetpoato leaf tissues infected with Pectobacterium chrysanthemi, indicating that swpa2 is involved in defense related to the pathogenesis of P. chrysanthemi in sweetpotato plants. These results strongly suggest that swpa2 gene is involved in overcoming oxidative stresses caused by both abiotic and biotic stress.

• Journal of Bio-Environment Control
• /
• v.28 no.4
• /
• pp.352-357
• /
• 2019

In this study, we investigated the limit temperature range which is effective for dormancy release of 'Hongro' and 'Fuji' apples during the endodormancy period. The germination rate was 50% or more in all treatments except of 'Hongro' $-5^{\circ}C$ treatment. The germination rate of 'Fuji' was 86.3% at the temperature of $-5^{\circ}C$. The concentrations of carbohydrate and mineral components were significantly different between treatments but did not show any tendency or specific change. However, the sorbitol contents of 'Hongro' $-5^{\circ}C$ treatment were higher at 29.62 mg/g than those of 'Fuji', which was not affected for dormancy release. The results of hormone analysis showed that ABA(abscisic acid) and JA(jasmonic acid) in 'Hongro' $-5^{\circ}C$ treatment were respectively 176.48 and 15.72 ng/g. ABA, JA and SA(salicylic acid) contents in 'Fuji' apple tree were significantly lower than those of 'Hongro'. As a result of this study, the limit temperature range effective for dormancy release was different according to the varieties, and 'Hongro' did not affect with 30.3% of germination rate at $-5^{\circ}C$. However, 'Fuji' is 86.3% even at $-5^{\circ}C$ it was suggested that 'Fuji' had a chilling accumulation for dormancy release.

• Journal of Plant Biology
• /
• v.33 no.2
• /
• pp.135-140
• /
• 1990

The membrane potential in the subepidermal cells of Lemna gibba G3 fronds was measured in the dark with glass capillary microelectrodes. At pH 7, the membrane potential, approximately-215 mV, could be depolarized to -82∼-88 mV by 0.1 mM dicyclohexylcarbodiimide (DCCD) or by KCN at 0.3 mM or higher concentrations. When the pH of the medium was altered the potential showed reversible changes, while it revealed no response to the external pH changes when energy transduction across the membrane was being blocked by 0.1 mM DCCD. The results support an assumption that the active component of the membrane potential of Lemna subepidermal cells is generated by electrogenic H+ -pump. By the addition of 0.10∼5.00 mM salicylic acid(SA) to the bathing medium the membrane potential was depolarized to a great extent, and the removal of SA from the medium repolarized the potential showing almost complete recovery, 92.3∼97.6% to the initial levels. Although the potential was greatly depolarized by 5.0% or higher concentrations of dimethylsulfoxide (DMSO), the recovery rate by DMSO removal was decreased as the pretreatment concentration had increased. Twenty percent DMSO pretreatment limited the recovery at only 47.1%. The presence of SA in the bathing medium could reversibly increase the permeability of the plasmalemma. DMSO at its concentration of 5.0% or higher increased the permeability of the membrane by irrevesibly impairing the membrane component involved in the membrane permeability.

• Journal of Bio-Environment Control
• /
• v.23 no.4
• /
• pp.329-336
• /
• 2014

As an abiotic stress, chilling stress is one of the major factors limiting plant growth and increasing susceptibility to pathogens. Therefore, enhancing stress tolerance in plants is an important strategy for their survival under unfavorable environmental conditions. The objective of this study was to determine the effects of the exogenous application of salicylic acid (SA) or nitric oxide (NO) on chilling tolerance in pepper seedlings. Pepper (Capsicum annuum L. 'kidaemanbal') seedlings were grown under normal growing conditions ($20/25^{\circ}C$, 15 hours photoperiod, $145{\pm}5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, fluorescence lamps) for 23 days after transplanting. The solution (3 mL) of 1 mM SA and 0.3 mM NO with surfactant triton 0.1% were sprayed two times a week, respectively. Right after the completion of chemical application, seedlings were subjected to chilling condition at $4^{\circ}C$ for 6 hours under dark condition and then the seedlings were recovered at the normal growing conditions for 2 days. In order to assess plant tolerance against chilling stress, growth characteristics, chlorophyll fluorescence (Fv/Fm), and membrane permeability were determined after chilling stress imposition. Total phenolic concentration and antioxidant capacity were measured during the whole experimental period. Disease incidence for pepper bacterial spot and wilt was also analyzed. Pepper seedlings treated with SA or NO were maintained similar dry mass ratio, while the value in control increased caused by chilling stress suggesting relatively more water loss in control plants. Electrolyte leakage of pepper seedlings treated with SA or NO was lower than that of control 2 days after chilling treatment. Fv/Fm rapidly decreased after chilling stress in control while the value of SA or NO was maintained about 0.8. SA increased higher total phenolic concentration and antioxidant capacity than NO and control during chemical treatment. In addition, increase in total phenolic concentration was observed after chilling stress in control and NO treatment. SA had an effect on the reduction of bacterial wilt in pepper seedlings. The results from this study revealed that pre-treatment with SA or NO using foliar spray was effective in chilling tolerance and the reduction of disease incidence in pepper seedlings.