• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.79.2-80
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• 2003

To better understand plant defense responses against pathogen attack, we identified the transcription factor-encoding genes in the hot pepper Capsicum annuum that show altered expression patterns during the hypersensitive response raised by challenge with bacterial pathogens. One of these genes, Ca1244, was characterized further. This gene encodes a plant-specific Type IIIA - zinc finger protein that contains two Cys$_2$His$_2$zinc fingers. Ca1244 expression is rapidly and specifically induced when pepper plants are challenged with bacterial pathogens to which they are resistant. In contrast, challenge with a pathogen to which the plants are susceptible only generates weak Ca1244 expression. Ca1244 expression is also strongly induced in pepper leaves by the exogenous application of ethephon, an ethylene releasing compound. Whereas, salicylic acid and methyl jasmonate had moderate effects. Pepper protoplasts expressing a Ca1244-smGFP fusion protein showed Ca1244 localizes in the nucleus. Transgenic tobacco plants overexpressing Ca1244 driven by the CaMV 355 promoter show increased resistance to challenge with a tobacco-specific bacterial pathogen. These plants also showed constitutive upregulation of the expression of multiple defense-related genes. These observations provide the first evidence that an Type IIIA - zinc finger protein, Ca1244, plays a crucial role in the activation of the pathogen defense response in plants.

• The Plant Pathology Journal
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• v.40 no.5
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• pp.438-450
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• 2024

Arabidopsis MORC1 (Microrchidia) is required for multiple levels of immunity. We identified 14 MORC1-interacting proteins (MIPs) via yeast two-hybrid screening, eight of which have confirmed or putative nuclear-associated functions. While a few MIP mutants displayed altered bacterial resistance, MIP13 was unusual. The MIP13 mutant was susceptible to Pseudomonas syringae, but when combined with morc1/2, it regained wild-type resistance; notably, morc1/2 is susceptible to the same pathogen. MIP13 encodes MED9, a mediator complex component that interfaces with RNA polymerase II and transcription factors. Expression analysis of defense genes PR1, PR2, and PR5 in response to avirulent P. syringae revealed that morc1/2 med9 expressed these genes in a slow but sustained manner, unlike its lower-order mutants. This expression pattern may explain the restored resistance and suggests that the interplay of MORC1/2 and MED9 might be important in curbing defense responses to maintain fitness. Indeed, repeated challenges with avirulent P. syringae triggered significant growth inhibition in morc1/2 med9, indicating that MED9 and MORC1 may play an important role in balancing defense and growth. Furthermore, the in planta interaction of MED9 and MORC1 occurred 24 h, not 6 h, post-infection, suggesting that the interaction functions late in the defense signaling. Our study reveals a complex interplay between MORC1 and MED9 in maintaining an optimal balance between defense and growth in Arabidopsis.

• Toxicological Research
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• v.30 no.2
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• pp.77-81
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• 2014

In contrast to animals, plants do not have a circulatory system as well as mobile immune cells that allow them to protect themselves against pathogens. Instead, plants exclusively depend on the innate immune system to defend against pathogens. As typically observed in the animal innate immunity, plant immune responses are composed of pathogen detection, defense signaling which includes transcriptional reprogramming, and secretion of antimicrobial compounds. Although knowledge on recognition and subsequent signaling of pathogen-derived molecules called elicitors is now expanding, the mechanisms of how these immune molecules are excreted are yet poorly understood. Therefore, current understandings of how plants secrete defense products especially via exocytosis will be discussed in this review.

• The Plant Pathology Journal
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• v.32 no.5
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• pp.377-387
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• 2016

Tomato yellow leaf curl virus (TYLCV), a member of the genus Begomovirus, is one of the most important viruses of cultivated tomatoes worldwide, mainly causing yellowing and curling of leaves with stunting in plants. TYLCV causes severe problems in sub-tropical and tropical countries, as well as in Korea. However, the mechanism of TYLCV infection remains unclear, although the function of each viral component has been identified. TYLCV C4 codes for a small protein involved in various cellular functions, including symptom determination, gene silencing, viral movement, and induction of the plant defense response. In this study, through yeast-two hybrid screenings, we identified TYLCV C4-interacting host proteins from both healthy and symptom-exhibiting tomato tissues, to determine the role of TYLCV C4 proteins in the infection processes. Comparative analyses of 28 proteins from healthy tissues and 36 from infected tissues showing interactions with TYLCV C4 indicated that TYLCV C4 mainly interacts with host proteins involved in translation, ubiquitination, and plant defense, and most interacting proteins differed between the two tissues but belong to similar molecular functional categories. Four proteins-two ribosomal proteins, S-adenosyl-L-homocysteine hydrolase, and 14-3-3 family protein-were detected in both tissues. Furthermore, the identified proteins in symptom-exhibiting tissues showed greater involvement in plant defenses. Some are key regulators, such as receptor-like kinases and pathogenesis-related proteins, of plant defenses. Thus, TYLCV C4 may contribute to the suppression of host defense during TYLCV infection and be involved in ubiquitination for viral infection.

• The Plant Pathology Journal
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• v.40 no.5
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• pp.537-550
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• 2024

Pectobacterium is a major bacterial causal agent leading to soft rot disease in host plants. With the Arabidopsis-Pectobacterium pathosystem, we investigated the function of an Arabidopsis thaliana WRKY55 during defense responses to Pectobacterium carotovorum ssp. carotovorum (Pcc). Pcc-infection specifically induced WRKY55 gene expression. The overexpression of WRKY55 was resistant to the Pcc infection, while wrky55 knockout plants compromised the defense responses against Pcc. WRKY55 expression was mediated via Arabidopsis COI1-dependent signaling pathway showing that WRKY55 can contribute to the gene expression of jasmonic acid-mediated defense marker genes such as PDF1.2 and LOX2. WRKY55 physically interacts with Arabidopsis ORA59 facilitating the expression of PDF1.2. Our results suggest that WRKY55 can function as a positive regulator for resistance against Pcc in Arabidopsis.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1999.10a
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• pp.39.2-39
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• 1999

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2004.10a
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• pp.24-24
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• 2004

See Full Text

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2002.11a
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• pp.3-4
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• 2002

• The Plant Pathology Journal
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• v.19 no.1
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• pp.9-12
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• 2003

• The Plant Pathology Journal
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• v.35 no.6
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• pp.609-622
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• 2019

Sound vibration (SV) treatment can trigger various molecular and physiological changes in plants. Previously, we showed that pre-exposure of Arabidopsis plants to SV boosts its defense response against Botrytis cinerea fungus. The present study was aimed to investigate the changes in the proteome states in the SV-treated Arabidopsis during disease progression. Proteomics analysis identified several upregulated proteins in the SV-infected plants (i.e., SV-treated plants carrying Botrytis infection). These upregulated proteins are involved in a plethora of biological functions, e.g., primary metabolism (i.e., glycolysis, tricarboxylic acid cycle, ATP synthesis, cysteine metabolism, and photosynthesis), redox homeostasis, and defense response. Additionally, our enzyme assays confirmed the enhanced activity of antioxidant enzymes in the SV-infected plants compared to control plants. Broadly, our results suggest that SV pre-treatment evokes a more efficient defense response in the SV-infected plants by modulating the primary metabolism and reactive oxygen species scavenging activity.