Plant Pathology Journal最新文献

Soybean (Glycine max [L.] Merr.) is a globally important crop; however, its productivity is severely constrained by the soybean cyst nematode (Heterodera glycines Ichinohe). This nematode often remains undetected during early infection and persists in the soil as dormant cysts, causing long-term yield losses. Although conventional detection methods, such as microscopic inspection and polymerase chain reaction assays, provide accuracy, they are labor-intensive and unsuitable for large-scale monitoring. Therefore, an artificial intelligence-based framework was established for the classification and segmentation of female soybean cyst nematodes using advanced deep learning architectures. Soil samples were collected from infected fields in South Korea and female nematodes were imaged with red-green-blue cameras under a dissecting microscope. Instance segmentation was benchmarked across YOLOv5, YOLOv8, YOLOv11, and Detectron2. The finetuned YOLOv11 model achieved the best performance, with a precision of 0.977, a recall of 0.980, and a mean Average Precision at 50% intersection-over-union of 0.988. Additionally, color-based phenotyping using hue-saturation-value thresholds classified 4,392 nematode images into yellow, orange, and brown groups, representing the reproductive and developmental stages. Consequently, this integrated framework highlights the potential of artificial intelligence-driven detection systems to reduce labor-intensive practices and support sustainable soybean production through the improved management of nematode-induced yield losses.

Cassava mosaic disease, caused by Cassava mosaic begomoviruses in the family Geminiviridae, poses a major threat to cassava production, with Sri Lankan cassava mosaic virus (SLCMV) being the dominant strain in Southeast Asia. Transmitted via infected propagative stems and whiteflies (Bemisia tabaci), SLCMV's impact on cassava metabolite dynamics remains poorly understood. This study investigated metabolite profile changes in resistant, tolerant, and susceptible cassava cultivars at 1, 3, and 7 days after inoculation by viruliferous whiteflies. Distinct metabolite patterns were observed among cultivars, with several pathways linked to plant defense identified, including flavonoid biosynthesis, phenylpropanoid biosynthesis, and purine metabolism. Secondary metabolite pathways, such as the energy-signaling SnRK1/AMPK-liked proteins, alpha-linolenic acid metabolism, and starch and sucrose metabolism, were also implicated. The results provide insights into metabolite-mediated defense mechanisms during early and late infection, enhancing understanding of cassava's responses to SLCMV inoculation after exposure to viruliferous whitefly infestation. This study supports the development of SLCMV-resistant cassava cultivars.

Northern corn leaf blight (NCLB), caused by Exserohilum turcicum (Setosphaeria turcica), is a major disease that negatively impacts the yield and quality of sweet corn. Plant-associated microbes hold great potential for enhancing crop productivity and sustainability. This study investigated the fungal and bacterial communities associated with NCLB in resistant and susceptible sweet corn cultivars using amplicon metagenomic sequencing. The structural composition and diversity of the fungal community in symptomatic NCLB-susceptible cultivars differed significantly from those in asymptomatic NCLB-resistant cultivars. In contrast, the bacterial communities showed no significant differences between resistant and susceptible cultivars in both the phyllosphere and rhizosphere. Exserohilum and Alternaria were significantly more abundant in the phyllosphere of symptomatic NCLB-susceptible plants, while fungal genera such as Sporobolomyces and Aureobasidium, along with the order Dothideales and the bacteria Bacillus, were significantly more abundant in the phyllosphere of asymptomatic NCLB-resistant cultivars. Microbial metabolic functions related to sugar metabolism-including sucrose biosynthesis and the degradation of glucose and xylose, compounds abundant in plant cell walls-were enriched in the phyllosphere of symptomatic NCLB-susceptible plants. In contrast, functions associated with detoxification and defense responses to plant phenolic compounds were enriched in microbes from asymptomatic NCLB-resistant cultivars. Additionally, Bacillus, identified ash part of the core microbiome, and the epiphytic yeast Sporobolomyces, identified as a hub in the microbial network, exhibited antimicrobial activity that may suppress E. turcicum. These findings offer valuable insights into the role of microbial communities in plant health and disease resistance, with promising implications for developing microbiome-based strategies to manage NCLB.

Abiotic stresses, such as drought and high salinity, threaten global food security by severely limiting crop yields. Among diverse agricultural practices, the usage of plant growth-promoting rhizobacteria has been expanding to enhance plant resilience against environmental stresses. In this study, we examined the effects of Bacillus subtilis W1-like strain (BsW1L) on increasing plant tolerance in lettuce plants (Lactuca sativa) grown under drought and high-salt stresses. BsW1L-treated plants exhibited improved tolerance to both stresses, as indicated by increased shoot and root growth, leaf area, and chlorophyll content. Application of the BsW1L strain enhanced the mRNA expression and activity of key antioxidant enzymes, catalase and ascorbate peroxidase. This facilitated the detoxification of reactive oxygen species, leading to decreased hydrogen peroxide levels, reduced malondialdehyde accumulation, and increased total soluble sugars. Notably, treatment with the BsW1L strain elevated proline levels in the leaves of lettuce plants grown under drought stress but reduced them in plants exposed to salt stress. Taken together, these findings suggest that BsW1L can serve as an ecofriendly biostimulant for improving plant tolerance to abiotic stresses, contributing to sustainable agricultural practices.

This study presents a comprehensive, long-term assessment of the performance and economic impact of virus-free (VF) apple seedlings distributed to commercial orchards in Korea. We compared VF and virus-infected (VI) 'Hongro' and 'Fuji' apple trees over five years, starting from four to five years after planting. VF trees maintained no reinfection for up to nine years, while VI trees showed a high infection rate (78.6%). VF trees consistently showed higher fruit set, greater yield, and superior fruit quality-including size, color, and soluble solids-than VI trees. VI trees produced more unmarketable fruit in both cultivars. Economic analysis showed that adopting VF seedlings increased net grower income by KRW 825,000 per 10 a. These results demonstrate that VF apple trees provide sustained improvements in productivity, fruit quality, and profitability in orchard conditions, supporting the continued expansion of VF seedling programs for sustainable apple production in Korea.

Fire blight, caused by Erwinia amylovora, is a highly destructive bacterial disease that affects apple and pear orchards worldwide, leading to significant economic losses. In this study, we isolated and characterized endophytic bacterial strains from apple trees in Gyeongsangbuk-do, South Korea, to identify potential biocontrol agents against E. amylovora. Among the five antagonistic strains identified, Bacillus velezensis JE80 and JE250 exhibited the strongest inhibitory effects. Further analysis using culture filtrates (CFs) from these strains demonstrated that the CFs of JE80 and JE250 not only suppressed E. amylovora growth in a growth-phase-dependent manner but also significantly impaired bacterial motility and biofilm formation. Notably, in planta assays revealed that JE250 effectively reduced fire blight symptoms in apple blossoms, performing comparably to streptomycin sulfate. Whole-genome sequencing of JE250 identified biosynthetic gene clusters associated with the production of antimicrobial compounds, including difficidin, fengycin, bacillaene, macrolactin, bacillibactin, and bacilysin, further supporting its strong antagonistic potential. These findings suggest that B. velezensis JE250 is a promising biocontrol agent for sustainable fire blight management. Future research should focus on optimizing formulation methods for field application, characterizing specific antimicrobial compounds, and evaluating its long-term efficacy in orchard environments.

Bacterial panicle blight (BPB) is a serious rice disease that causes spikelet abortion and yield loss under high-temperature and humid conditions. To identify the genetic basis of BPB resistance, we performed a genomewide association study (GWAS) using 307 Korean rice cultivars. A significant quantitative trait locus (QTL), qBG6.1, was identified on chromosome 6, with a lead single nucleotide polymorphism surpassing the genome-wide significance threshold. Within this QTL, haplotype analysis based on whole-genome resequencing data from 157 accessions revealed two candidate genes significantly associated with the percentage of healthy seeds per panicle: Os06g0255900 and Os06g0259850. These genes encode proteins with functions related to exocyst-mediated vesicle trafficking (EXO70F5) and pathogen response (tobacco mosaic virus [TMV]-related protein), respectively, indicating their potential involvement in BPB resistance mechanisms. Our findings highlight the value of integrating GWAS and haplotype analysis to dissect complex traits such as disease resistance. Although the functional roles of these candidate genes require further validation, they represent promising targets for molecular breeding and future genetic studies aimed at developing BPB-resistant rice cultivars.

Fire blight, caused by Erwinia amylovora, poses a significant threat to Rosaceae crops and has caused substantial damage to South Korea since its emergence in 2015. Traditional control methods, including antibiotic- and copper-based treatments, have shown limitations, underscoring the necessity for alternative solutions to enhance efficacy while addressing the concerns associated with antibiotics. This study evaluated the efficacy of FireFighter-A, a novel phage cocktail, in managing fire blight. Comprising four phages-Fifi318, Fifi451, pEa_27, and pEa_47-FireFighter-A demonstrates a broad host range that covers all recent isolates against E. amylovora and E. pyrifoliae, along with high stability under various conditions, including temperature, pH, and buffers. Trials with immature apple fruits, tissue culture rootstock plantlets, acclimated M26 rootstock plantlets, and blossoms have demonstrated that FireFighter-A provides superior biocontrol efficacy through synergistic effects, outperforming individual phages. Moreover, it significantly reduced fire blight symptoms and infection rates with a performance comparable to or exceeding that of streptomycin. These findings support the use of FireFighter-A as an effective and environment-friendly alternative for fire blight control.

The Fusarium fujikuroi species complex (FFSC) includes numerous phytopathogenic and mycotoxigenic species of significant agricultural importance. In this study, 81 Korean isolates within the FFSC from the Korean Agricultural Culture Collection (KACC) were re-identified using multi-locus sequence analyses of partial gene fragments of the translation elongation factor 1-alpha (tef1), beta-tubulin (tub2), calmodulin (CaM), RNA polymerase II largest subunit (rpb1), and RNA polymerase II second largest subunit (rpb2). Phylogenetic analyses clarified the taxonomic identities of these isolates, revealing that many strains previously reported as F. proliferatum, F. subglutinans, and F. circinatum were re-identified as F. annulatum, F. dendrobii, and a novel species, F. ipomoeicola sp. nov., respectively. In total, eight species were confirmed within the FFSC, including seven known species (F. annulatum, F. concentricum, F. dendrobii, F. elaeagni, F. fujikuroi, F. planum, and F. thapsinum) and one novel species described herein. Notably, the taxonomic status of four recently described species was revised, indicating that F. hipposidericola, F. jacksoniae, F. xishuangbannaense, and F. oryzigenum are synonyms of F. annulatum, F. babinda, F. hechiense, and F. planum, respectively. In addition, F. annulatum, F. dendrobii, F. elaeagni, and F. planum are reported for the first time in Korea, and 22 previously undocumented fungus-host associations from Korea were identified, including 15 novel combinations not previously reported worldwide. However, the pathogenicity of these fungal species on their respective hosts was not confirmed in this study.

Seeds harbor diverse microbial communities, including endophytes, some of which are vertically transmitted and may contribute to plant health and productivity. However, the temporal dynamics of seed endophytic communities remain poorly understood in many crop species. In this study, we monitored the composition of bacterial and fungal endophytes in soybean (Glycine max) seeds, along with rhizosphere microbiomes, across three plant generations using a culture-independent approach. Our results revealed two key patterns: seed endophytic communities are distinct from those of bulk soil and rhizosphere microbiomes; and the composition of seed endophytes fluctuates over generations, likely influenced by both pre-existing endophytes, environmental factors, and microbial influx from the surrounding soil and rhizosphere, suggesting possible microbial transmission from the rhizosphere into seeds. Interestingly, despite generational variation, the seed fungal endophyte communities consistently maintained higher phylogenetic diversity compared to bacterial endophytes, which showed limited overlap across generations and were composed of fewer, closely related taxa. Analysis of community assembly mechanisms indicated that both seed and rhizosphere microbiomes significantly contributed to the next generation of seed microbiota, primarily through stochastic drift and homogeneous selection processes. Collectively, our findings offer valuable insights into the intergenerational dynamics of seed endophytes in soybean and provide a foundation for future efforts to harness seed-associated microbiomes for improving crop health and productivity.