Phytobiome as a Potential Factor in Nitrogen-Induced Susceptibility to the Rice Blast Disease

Jeon, Junhyun The Korean Society of Plant Pathology 2019 식물병연구 Vol.25 No.3

Roles of nutrients in controlling plant diseases have been documented for a long time. Among the nutrients having impact on susceptibility/resistance to crop diseases, nitrogen is one of the most important nutrients for plant growth and development. In rice plants, excess nitrogen via fertilization in agricultural systems is known to increase susceptibility to the rice blast disease. Mechanisms underlying such phenomenon, despite its implication in yield and sustainable agriculture, have not been fully elucidated yet. A few research efforts attempted to link nitrogen-induced susceptibility to concomitant changes in rice plant and rice blast fungus in response to excess nitrogen. However, recent studies focusing on phytobiome are offering new insights into effects of nitrogen on interaction between plants and pathogens. In this review, I will first briefly describe importance of nitrogen as a key nutrient for plants and what changes excess nitrogen can bring about in rice and the fungal pathogen. Next, I will highlight some of the recent phytobiome studies relevant to nitrogen utilization and immunity of plants. Finally, I propose the hypothesis that changes in phytobiome upon excessive nitrogen fertilization contribute to nitrogen-induced susceptibility, and discuss empirical evidences that are needed to support the hypothesis.

Phytobiome as a Potential Factor in Nitrogen-Induced Susceptibility to the Rice Blast Disease

Junhyun Jeon 한국식물병리학회 2019 식물병연구 Vol.25 No.3

Roles of nutrients in controlling plant diseases have been documented for a long time. Among the nutrients having impact on susceptibility/resistance to crop diseases, nitrogen is one of the most important nutrients for plant growth and development. In rice plants, excess nitrogen via fertilization in agricultural systems is known to increase susceptibility to the rice blast disease. Mechanisms underlying such phenomenon, despite its implication in yield and sustainable agriculture, have not been fully elucidated yet. A few research efforts attempted to link nitrogen-induced susceptibility to concomitant changes in rice plant and rice blast fungus in response to excess nitrogen. However, recent studies focusing on phytobiome are offering new insights into effects of nitrogen on interaction between plants and pathogens. In this review, I will first briefly describe importance of nitrogen as a key nutrient for plants and what changes excess nitrogen can bring about in rice and the fungal pathogen. Next, I will highlight some of the recent phytobiome studies relevant to nitrogen utilization and immunity of plants. Finally, I propose the hypothesis that changes in phytobiome upon excessive nitrogen fertilization contribute to nitrogen-induced susceptibility, and discuss empirical evidences that are needed to support the hypothesis.

A putative MAP kinase kinase kinase, MCK1, is required for cell wall integrity and pathogenicity of the rice blast fungus, Magnaporthe oryzae.

Jeon, Junhyun,Goh, Jaeduk,Yoo, Sungyong,Chi, Myoung-Hwan,Choi, Jaehyuk,Rho, Hee-Sool,Park, Jongsun,Han, Seong-Sook,Kim, Byeong Ryun,Park, Sook-Young,Kim, Soonok,Lee, Yong-Hwan APS Press 2008 Molecular plant-microbe interactions Vol.21 No.5

<P>Insertional mutagenesis of Magnaporthe oryzae led to the identification of MCK1, a pathogenicity gene predicted to encode mitogen-activated protein kinase kinase kinase (MAPKKK) homologous to BCK1 in Saccharomyces cerevisiae. Targeted disruption of MCK1 resulted in the fungus undergoing autolysis and showing hypersensitivity to cell-wall-degrading enzyme. The mck1 produced significantly reduced numbers of conidia and developed appressoria in a slightly retarded manner compared with the wild type. Appressorium of the mck1 mutant was unable to penetrate into plant tissues, thereby rendering the mutant nonpathogenic. Cytorrhysis assay and monitoring of lipid mobilization suggested that the appressorial wall was altered, presumably affecting the level of turgor pressure within appressorium. Furthermore, the mck1 mutant failed to grow inside plant tissue. Complementation of the mutated gene restored its ability to cause disease symptoms, demonstrating that MCK1 is required for fungal pathogenicity. Taken together, our results suggest that MCK1 is an MAPKKK involved in maintaining cell wall integrity of M. oryzae, and that remodeling of the cell wall in response to host environments is essential for fungal pathogenesis.</P>

A Brief Guide to Statistical Analysis and Presentation for the Plant Pathology Journal

Junhyun Jeon 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.4

Functional genomics in the rice blast fungus to unravel the fungal pathogenicity.

Jeon, Junhyun,Choi, Jaehyuk,Park, Jongsun,Lee, Yong-Hwan Zhejiang University Press 2008 Journal of Zhejiang University. Science B. Biomedi Vol.9 No.10

<P>A rapidly growing number of successful genome sequencing projects in plant pathogenic fungi greatly increase the demands for tools and methodologies to study fungal pathogenicity at genomic scale. Magnaporthe oryzae is an economically important plant pathogenic fungus whose genome is fully sequenced. Recently we have reported the development and application of functional genomics platform technologies in M. oryzae. This model approach would have many practical ramifications in design and implementation of upcoming functional genomics studies of filamentous fungi aimed at understanding fungal pathogenicity.</P>

Histone Acetylation in Fungal Pathogens of Plants

Jeon, Junhyun,Kwon, Seomun,Lee, Yong-Hwan The Korean Society of Plant Pathology 2014 Plant Pathology Journal Vol.30 No.1

Acetylation of histone lysine residues occurs in different organisms ranging from yeast to plants and mammals for the regulation of diverse cellular processes. With the identification of enzymes that create or reverse this modification, our understanding on histone acetylation has expanded at an amazing pace during the last two decades. In fungal pathogens of plants, however, the importance of such modification has only just begun to be appreciated in the recent years and there is a dearth of information on how histone acetylation is implicated in fungal pathogenesis. This review covers the current status of research related to histone acetylation in plant pathogenic fungi and considers relevant findings in the interaction between fungal pathogens and host plants. We first describe the families of histone acetyltransferases and deacetylases. Then we provide the cases where histone acetylation was investigated in the context of fungal pathogenesis. Finally, future directions and perspectives in epigenetics of fungal pathogenesis are discussed.

RNA Modification and Its Implication in Plant Pathogenic Fungi

Junhyun Jeon,Song Hee Lee 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.6

Interaction of a pathogen with its host plant requires both flexibility and rapid shift in gene expression programs in response to environmental cues associated with host cells. Recently, a growing volume of data on the diversity and ubiquity of internal RNA modifica- tions has led to the realization that such modifications are highly dynamic and yet evolutionarily conserved system. This hints at these RNA modifications being an additional regulatory layer for genetic information, cul- minating in epitranscriptome concept. In plant patho- genic fungi, however, the presence and the biological roles of RNA modifications are largely unknown. Here we delineate types of RNA modifications, and provide examples demonstrating roles of such modifications in biology of filamentous fungi including fungal patho- gens. We also discuss the possibility that RNA modifica- tion systems in fungal pathogens could be a prospective target for new agrochemicals.

A Brief Guide to Statistical Analysis and Presentation for the Plant Pathology Journal

전준현(Junhyun Jeon) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.3

Statistical analysis of data is an integral part of research projects in all scientific disciplines including the plant pathology. Appropriate design, application and interpretation of statistical analysis are also, therefore, at the center of publishing and properly evaluating studies in plant pathology. A survey of research works published in the Plant Pathology Journal, however, cast doubt on high standard of statistical analysis required for scientific rigor and reproducibility in the journal. Here I first describe, based on the survey of published works, what mistakes are commonly made and what components are often lacking during statistical analysis and interpretation of its results. Next, I provide possible remedies and suggestions to help guide researchers in preparing manuscript and reviewers in evaluating manuscripts submitted to the Plant Pathology Journal. This is not aiming at delineating technical and practical details of particular statistical methods or approaches.

Large-Scale Screening of the Plant Extracts for Antifungal Activity against the Plant Pathogenic Fungi

Song Hee Lee(Song Hee Lee),Young Taek Oh(Young Taek Oh),Do-Yeon Lee(Do-Yeon Lee),Eunbyeol Cho(Eunbyeol Cho),Byung Su Hwang(Byung Su Hwang),Junhyun Jeon(Junhyun Jeon) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.6

Plants produce chemicals of immense diversity that provide great opportunities for development of new antifungal compounds. In search for environmentfriendly alternatives to the fungicide of current use, we screened plant extracts obtained from more than eight hundred plant materials collected in Korea for their antifungal activity against the model plant pathogenic fungus, Magnaporthe oryzae. This initial screening identified antifungal activities from the eleven plant extract samples, among which nine showed reproducibility in the follow-up screening. These nine samples were able to suppress not only M. oryzae but also other fungal pathogens. Interestingly, the plant extracts obtained from Actinostemma lobatum comprised five out of eight samples, and were the most effective in their antifungal activity. We found that butanol fraction of the A. lobatum extract is the most potent. Identification and characterization of antifungal substances in the A. lobatum extracts would provide the promising lead compounds for new fungicide.

Variation of Floating Potential in the Topside Ionosphere Observed by STSAT-1

Junhyun Lee,Ensang Lee,Jaejin Lee,Khan-Hyuk Kim,Jongho Seon,Dong-Hun Lee,Ho Jin,Eung-Hyun Kim,Hyun-Jin Jeon,Seong-Bin Lim,Taeyoun Kim,Jaewoong Jang,Kyung-Duk Jang,Kwangsun Ryu 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.4

In this study, we investigated the effect of space plasmas on the floating potential variation of a low-altitude, polar-orbiting satellite using the Langmuir Probe (LP) measurement onboard the STSAT-1 spacecraft. We focused on small potential drops, for which the estimation of plasma density and temperature from LP is available. The floating potential varied according to the variations of plasma density and temperature, similar to the previously reported observations. Most of the potential drops occurred around the nightside auroral region. However, unlike the previous studies where large potential drops were observed with the precipitation of auroral electrons, the potential drops occurred before or after the precipitation of auroral electrons. Statistical analysis shows that the potential drops have good correlation with the temperature increase of cold electrons, which suggests the small potential drops be mainly controlled by the cold ionospheric plasmas.