Cherry trees (Prunus serrulata var. spontanea, Prunus × yedoensis), a widely cultivated ornamental street trees grown in Korea, are vulnerable to variety of diseases particularly the prevailing brown shot-hole disease, thus needs effective maintenance strategies for optimum plant growth and observation. The major fungal genera causing cherry brown shot-hole disease in Korea were identified as Alternaria, Diaporthe, Epicoccum, and Botryosphaeria, and their resistance to tebuconazole and difenoconazole was investigated. Both fungicides are classified as demethylation inhibitors and the emergence of resistant strains has been reported worldwide. In this study, we found significant differences in fungicide resistance depending on the type of pathogen and regional differences and performed base sequence analysis of the CYP51 gene on some Alternaria isolates with fungicide resistance to confirm the occurrence of point mutations and amino acid substitutions. However, point mutations were not detected in some resistant Alternaria isolates, suggesting that the resistance of some isolates is possibly unrelated to the alterations in the target site or may be due to genetic variations in unidentified genomic sequence CYP51 gene. These results will contribute to understanding the mechanism of antifungal resistance development in fungal plant pathogens and are expected to contribute to the control of brown shot hole disease in cherry trees.

Plant virus diseases reduce crop yield and quality worldwide; moreover, curative options once systemic infection is established remain scarce. Non-thermal plasma (NTP; cold atmospheric plasma) is a residuefree, near-ambient technology that generates reactive oxygen and nitrogen species (RONS) with strong virucidal activity. This review summarizes major sources of NTP, including dielectric barrier discharges, plasma jets, and corona/streamer discharges; plasma chemistry in gas and liquid phases; molecular mechanisms of virus inactivation, including capsid protein oxidation/denaturation, limited lipid peroxidation in enveloped plant viruses, and genome damage that suppresses replication. Evidence from plant virus studies indicates that highly stable viruses lose infectivity and that waterborne inactivation is efficient, supporting the use of NTP and plasma-activated water as practical tools for sanitizing irrigation water, recirculating hydroponic solutions, and contact surfaces. Emerging greenhouse studies have suggested that plasma-generated oxidants, including ozone, can curb water-mediated dissemination. Hence, we compare NTP with thermotherapy, irradiation, and chemical antiviral approaches, and discuss safety, scalability, and economic considerations. Key priorities for translation include standardized dose and chemistry metrics, infectivity-based endpoints in realistic matrices, scalable reactors that ensure uniform treatment at high throughput, and multi-site validation under commercial production conditions.

Rice is a crucial global crop of nutritional and economic importance. Burkholderia glumae, Burkholderia gladioli, and Burkholderia plantarii are the major phytopathogens that cause diseases in rice within the genus Burkholderia. These phytopathogenic Burkholderia spp. have an acylated homoserine lactone (AHL)-based quorum sensing (QS) system that regulates gene expression depending on the cell density. Differentially expressed genes (DEGs) between B. plantarii KACC 18965 wildtype and plaI deletion mutant were analyzed to understand the plaI-mediated QS system in B. plantarii, and transcriptome profiles were compared across three phytopathogenic Burkholderia spp. (B. glumae, B. gladioli, and B. plantarii) to investigate the impact of QS on their pathogenicity. Clusters of Orthologous Groups category and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses confirmed that diverse metabolic processes were regulated by QS in the three phytopathogenic Burkholderia spp. Additionally, characteristic differences in the regulation of gene expression across the three phytopathogenic Burkholderia spp. were observed in DEGs belonging to the bacterial secretion system (ko03070) pathway, using KEGG pathway analysis. The characterization and comparison of transcriptome profiles between phytopathogenic Burkholderia spp. in this study offers deeper insights into AHL-mediated QS systems in phytopathogenic Burkholderia spp. These results provide a foundation for future studies on the QS-based biology and pathogenicity of phytopathogenic Burkholderia spp.

Viruses, a group of non-cellular parasites, pose serious threats to human health and agriculture. While viral genetic variations modulating virus adaptation to biotic stresses have been reported, whether and how they affect virus interactions with abiotic stresses such as high temperature remain unknown. Here, we report the impact of AV2 mutations on the life cycle of squash leaf curl China virus (SLCCNV), a bipartite begomoviruses. We first conducted sequence analysis and identified a naturally-occurring mutation at position 35 in AV2 that changes the codon TGG to TAG. Followed analysis revealed that this mutation did not significantly impact SLCCNV infectivity and transmission under both ambient and high temperatures. Next, we changed the start codon of AV2 to stop codon. While the mutation of start codon did not impact SLCCNV infection under ambient temperature, under high temperatures mutant SLCCNV displayed decreased infectivity. We then examined the underpinnings of AV2 function, and found that AV2 cannot compensate for the function of other viral genes and its expression relative to other viral genes was not induced at high temperature. Moreover, protein encoded by AV2 suppressed posttranscriptional gene silencing under both ambient and high temperatures. Our study unravels a novel function of viral factors in the regulation of begomovirus infection under high temperature, and sheds new lights on virus adaptation to abiotic stresses.

Lectin receptor-like kinases (LecRLKs) are plant-specific kinases that play critical roles in stress signaling. G-type LecRLKs, which possess an α-mannose-binding bulb lectin domain, are implicated in diverse stress responses; however, their roles in drought responses in pepper plants remain poorly understood. Therefore, this study aims to identify and functionally characterize a pepper G-type LecRLK, CaRLK1. CaRLK1 expression was significantly induced by multiple abiotic stresses, particularly dehydration. Additionally, functional analysis using virus-induced gene silencing revealed that CaRLK1-silenced pepper plants showed reduced drought tolerance and increased leaf water loss, associated with impaired stomatal closure and attenuated leaf temperature increases following abscisic acid (ABA) treatment. Moreover, CaRLK1 silencing reduced the expression of several drought-responsive genes, including CaOSR1, CaDREBLP1, and CaLOX1, under dehydration conditions. Collectively, these findings suggest that CaRLK1 functions as a positive regulator of drought stress responses in pepper plants by modulating ABA-dependent stomatal aperture dynamics and drought-responsive gene expression.

The circular leaf disease, caused by Pestalotiopsis spp., is a new primary foliar disease characterized by yellow-brown lesions that develop into dark-brown lesions on rubber leaves. This disease, named leaf fall disease, has recently led to significant economic losses in countries that produce natural rubber. However, molecular mechanisms that are involved in the interaction between P. microspora and rubber tree (Hevea brasiliensis) remain unclear. In this study, we conducted transcriptome analysis using RNA-seq of a susceptible rubber clone (GT1) after an inoculation with the mycelial plug of P. microspora. Among 84,443 rubber genes, the analysis revealed 3,799, 7,274, and 4,678 differentially expressed genes (DEGs) at 2, 4, and 6 days post-infection (dpi), respectively. Our Gene Ontology analysis of the DEGs detected the GO terms of the general hypersensitive response and systemic acquired resistance, which is known to be mediated by salicylic acid and hydrogen peroxide. We also detected the GO terms related to abscisic acid and ethylene responses. In addition, the detection of these two phytohormone transcriptional responses suggests the possible involvement of abscisic acid and/or ethylene in the process that led to the leaf fall symptom in susceptible rubber. Further, our promoter analysis to extract putative promoter elements responsive to the pathogen supported ethylene signaling activation by the pathogen infection. In addition, we extracted general Regulatory Element Groups that are position-dependent cis-regulatory elements, and established molecular markers for quantitative reverse transcription polymerase chain reaction. Our study provides genomic information and convenient tools for facilitating further exploration of Hevea-Pestalotiopsis interaction.

Verticillium wilt, caused by Verticillium dahliae and V. longisporum, has emerged as a serious threat to Chinese cabbage production in Korea. To clarify the population structure, pathogenicity, and host range of these pathogens, we collected 60 isolates from major Chinese cabbage-growing regions and conducted multilocus phylogenetic analyses based on five nuclear genes. Pathogenicity assays were carried out on Chinese cabbage, and host range assays were conducted on diverse crops. The results showed that V. longisporum lineage A1/D1, the predominant lineage in Europe and North America, dominated across all surveyed regions, while a single A1/D3 lineage isolate was detected for the first time in Korea. Pathogenicity tests demonstrated that V. longisporum was generally more aggressive on Chinese cabbage than V. dahliae, with the A1/D3 isolate displaying the highest virulence among all isolates tested. Host range assays revealed that V. longisporum was restricted to cruciferous crops, whereas V. dahliae infected crucifers as well as solanaceous and several other crops, indicating broader epidemiological risks. Non-host crops such as barley, buckwheat, carrot, maize, and sudangrass were not infected by either species, suggesting their potential use in crop rotation. Collectively, these findings demonstrate that V. longisporum, particularly lineage A1/D1, is the major causal agent of Verticillium wilt epidemics in Korean Chinese cabbage production. The detection of aggressive A1/D3 lineage and genetically diverse V. dahliae populations underscores additional long-term risks that necessitate continuous monitoring, resistance breeding, and integrated disease management.

Fusarium basal rot (FBR) poses a serious threat to onion (Allium cepa L.) production worldwide. In South Korea, FBR is primarily associated with Fusarium oxysporum, F. commune, and F. proliferatum. To investigate the relationship between effector gene profiles and virulence, we screened 34 isolates collected from FBR-affected fields for 14 Secreted in Xylem (SIX) genes and three additional effector candidates (CRX1, CRX2, and C5). F. oxysporum isolates carrying the effector suite SIX3, SIX5, SIX7, SIX9, SIX10, SIX12, SIX14, together with CRX1, CRX2 and C5, exhibited significantly higher aggressiveness on onion seedlings and bulbs than effector-negative strains. Among F. commune isolates lacking SIX genes, those carrying both CRX1 and CRX2 tended to show greater pathogenicity than CRX-negative strains. Nevertheless, SIX-negative strains still caused substantial seedling loss and bulb-rot, indicating the involvement of SIX-independent virulence factors. All F. proliferatum isolates were comparably pathogenic to SIX-negative F. oxysporum and F. commune strains, and uniformly carried SIX2-1 and CRX2, with a subset also harboring the SIX2-2 homologue. Across all isolates, SIX9 was the most frequently detected SIX gene and was markedly enriched in strains exhibiting strong pathogenicity. We developed and validated a SIX9-targeted quantitative PCR (qPCR) assay that specifically detects SIX9-positive Fusarium isolates (mainly F. oxysporum and F. commune), with detection limits of 1 pg of DNA or 10⁴ conidia/g soil. These findings enhance our understanding of effector repertoires contributing to Fusarium pathogenicity on onion and provide a molecular tool to support FBR diagnosis.

Wildfire, caused by Pseudomonas amygdali pv. tabaci (Pat), is a severe bacterial disease of soybean [Glycine max (L.) Merr.]. Enhancing resistance to wildfire is an important breeding goal, yet genetic studies remain limited. This study aimed to identify quantitative trait loci (QTL) associated with partial resistance to Pat using a Daepung × Taekwang recombinant inbred line (RIL) population. Sixty RILs were evaluated for resistance to the Pat isolate 'W14-M1'. Two QTL associated with resistance to Pat were identified on chromosomes 4 and 5, explaining 14.1% and 19.1% of the phenotypic variance, respectively. Daepung contributed the resistance alleles at both loci. The identified genomic regions overlapped with previously reported resistance QTL for bacterial, fungal, and nematode Pathogens. These findings indicate that Daepung is a valuable source of resistance to Pat, and the detected QTL may facilitate the development of molecular markers for pyramiding multiple disease resistance traits in soybean breeding program.

Bacterial identification and classification are commonly performed based on the sequence of the 16S rRNA and several gold-standard marker genes, such as gyrB and recA. However, certain bacterial genera, including Xanthomonas and Pseudomonas, present challenges in clear classification at the species or subspecies level using these single-marker genes. Here, we explored the potential of the rfbA gene as a novel marker for bacterial classification. The rfbA gene, involved in lipopolysaccharide synthesis, is a conserved gene present in most gram-negative bacteria and is sufficiently short (approximately 850 bp). In this study, we identified that rfbA has undergone host-specific adaptive evolution, distinguishing it from conserved housekeeping genes. Therefore, we targeted Xanthomonas and Pseudomonas species to demonstrate the utility of rfbA in resolving taxonomic challenges at the pathovar level. These differences were strongly associated with the hosts of the respective strains, suggesting a potential evolutionary link between rfbA variation and host specificity.