Plant Pathology Journal最新文献

Chlorella is a genus of aquatic photosynthetic microalgae used in the production of dietary supplements, cosmetics, and biofuels, and also recently utilized as biological control agents or biofertilizers in agricultural supplements. Chlorella supernatant elicits induced resistance in Arabidopsis thaliana but its effects on crop plants remain largely unknown. This study tested whether application of Chlorella supernatant elicited induced resistance in cucumber (Cucumis sativus L.). Foliar application of supernatants from six microalgal strains revealed that supernatants from the high biofuel-producing strains HS2 and ABC001 elicited induced resistance against Pseudomonas syringae pv. lachrymans, which causes angular leaf spot in cucumber. In addition, spraying plants with D-lactic acid, a previously known determinant of induced resistance in the Chlorella supernatant, reduced the severity of disease caused by P. syringae pv. lachrymans in cucumber leaves by activating the salicylic acid and jasmonic acid signaling pathways. The application of Chlorella supernatant thus protects a crop plant against disease while offering a cost-effective method of recycling waste supernatant.

Pratylenchus penetrans, an important soil pathogen, has been reported on various crops in the temperate regions of South Korea. In concern, there is an urgent need for a precise, species-specific quantitative polymerase chain reaction (qPCR) kit to detect and quantify root lesion nematodes for early pest management and to controls yield losses. The present study focuses on D2-D3 region, a known marker for molecular profiling of Pratylenchus sp. A primer set mined from the highly conserved D2-D3 region of P. penetrans was used in a SYBR green based qPCR assay. Initial examination identified P. penetrans from infested soil samples using morphological and phylogenetic analyses. The DPp7F12R primer set demonstrated significant specificity in identifying P. penetrants by both conventional polymerase chain reaction (PCR) and qPCR assays. Linear regression of serially diluted DNA from nematode and nematode inoculated soil revealed a limit of quantification of 2 picograms (r² = 0.984), while also highlighting the impact of soil inhibitors. The qPCR using the DNA from varying densities of P. penetrans inoculated in soil demonstrated a robust correlation (r² = 0.98), indicating the limit of detection down to single nematode. Primer specificity evaluation with field soil sample precisely detected only P. penetrants. Species-specific DPp7F12R facilitate the direct detection of P. penetrants from soil DNA in very shorter time. Reliability of PCR was confirmed using BLAST algorithm, which identified partial sequence of PCR amplicon (300 bp) as P. penetrants. Finally, PCR assay using DPp7F12R is crucial for early detection of P. penetrans infestations, helping improve the plant health.

Fire blight disease, caused by Erwinia amylovora, occurs in apples and other Rosaceae plants and is known to cause significant economic damage. The pathogen usually infects flowers during the reproductive growth period of plants, colonizes, and penetrates by producing exopolysaccharides in the stigma. A synthetic microbial community (SynCom) is an artificial community of microorganisms designed to enhance host viability. To construct SynCom, we attempted to identify and utilize the microbial characteristics of apple trees that are not infected with the pathogen compared to those that are infected. In our previous study, we composed SynCom with strains expected to reduce the density of fire blight pathogens through microbiome analysis, strain isolation, and continuous replacement culture. We are able to observe the disease control effect of the constructed SynCom. However, no study has been conducted to clearly determine the genetic mechanism underlying this effect of the SynCom. Here, we present that potential secondary metabolite candidates and nutritional competition with the pathogen were confirmed as biochemical mechanisms through whole genome analysis of SynCom strains. Additionally, by co-cultivating SynCom with the pathogen in limited nutrient conditions, such as apple blossom extracts, which are susceptible to the pathogen, we confirmed the potential of SynCom treatment to reduce the pathogen densities. This study demonstrates that genetic selection using metagenomics can effectively identify microorganisms with potential functional capabilities.

Melothria scabra, an annual vine plant belonging to the family Cucurbitaceae, is usually found as a weed in agricultural ecosystems, making it a potential reservoir for crop viruses. Nonetheless, no plant virus has been documented to infect M. scabra to date. In the present study, M. scabra leaves with plant virus disease symptoms were sampled and subjected to sequencing through metatranscriptome and small RNA methods. High-throughput data analysis revealed the presence of two potyvirus species, zucchini tigre mosaic virus (ZTMV) and zucchini yellow mosaic virus (ZYMV), which were subsequently confirmed through reverse transcription PCR (RT-PCR) detection. The complete genome sequences of ZTMV and ZYMV in M. scabra, designated as ZTMV-ms (PQ720520) and ZYMV-ms (PQ720521), were determined by a combination of RT-PCR, rapid amplification of cDNA ends and Sanger sequencing. The full-genome length of ZTMV-ms and ZYMV-ms is 10,331 nt and 9,602 nt, respectively, excluding the 3' poly(A) tail. Notably, ZYMV-ms showed 80.15% similarity to its best BLASTn hit (AJ515911.1, ZYMV-WM), approaching the threshold for defining new Potyvirus species, thus classifying ZYMV-ms as a highly divergent ZYMV isolate. Both ZTMV-ms and ZYMV-ms show typical virus-derived small interfering RNA (vsiRNAs) characteristics of plant viruses, with 21- and 22-nt vsiRNAs, the latter being the most abundant, a feature rare among plant viruses. These findings provide new insights into the diversity of plant host antiviral RNAi response, as well as the evolution and host expansion of ZTMV and ZYMV, with implications for virus prevention and control.

Tomato yellow leaf curl virus (TYLCV) is a devastating pathogen that causes substantial yield losses, and this virus can infect both tomatoes (Solanum lycopersicum L.) and tobacco (Nicotiana benthamiana). In this study, a constructed infectious clone of TYLCV was used for the exploration of tomato and tobacco plants' response to virus infection. Infected plants exhibit typical symptoms of TYLCV, including leaf chlorosis, curling, and plant dwarfing. Reactive oxygen species accumulated, and severe cell necrosis appeared in the tomatoes and tobacco that were infected. After TYLCV infection, 6,775 and 900 genes' expressions were up-regulated in tomatoes and tobacco, including MYB and MADS-box transcription factors, serine/threonine protein kinase, heat shock proteins, cytochrome P450s, E3 ubiquitin-protein ligase, RAV transcription factors. Several stress-responsive kinases involved in autophagy were significantly up-regulated in tobacco but not in tomato. Moreover, silencing the RAV transcription factor, which is associated with the salicylic acid induced antiviral signaling, led to decreased virus abundance in tomato leaves. The results are helpful for an in-depth understanding of plants' resistance to TYLCV infection.

In 2022, a wilt disease was found in the melon in central Taiwan, resulting in severe yield losses. To identify the causal agent, both morphological and molecular identification were conducted. Together with the results of host range tests, the pathogen was identified as Fusarium oxysporum f. sp. melonis race 2 (FOM). To develop a sustainable and eco-friendly method for disease management, the culture broth and culture filtrate of two potential biocontrol agents, Bacillus mycoides strains BM02 and BM103, were evaluated against FOM in a greenhouse. The results revealed that B. mycoides strain BM02 consistently and significantly (P < 0.05) reduced the disease when applied via foliar spraying or soil-drenching, compared to the water control. To our knowledge, this is the first report confirming FOM race 2 in Taiwan and the biocontrol results suggested that BM02 could be promising for managing melon Fusarium wilt.

Sweet pepper (Capsicum annuum) is a highly nutritious and economically important vegetable grown worldwide. Black mold, caused by mycotoxin-producing Alternaria spp., is a common postharvest disease during cold storage and transport, leading to significant produce losses. A better understanding of the infection process is essential for improving disease control. This study examined Alternaria alternata isolates infecting green (mature unripe) and red (ripe) pepper fruit. Findings indicate that black mold can infect fruit at both ripening stages, with differences in symptom progression, growth rates, and sporulation. Disease development was influenced by fruit ripeness in a temperature-dependent manner. At 7°C, lesion size and sporulation were similar on green and red fruit, but at 22°C, lesions were significantly larger on red fruit (P < 0.05). Microscopic studies revealed comparable conidial germination on both fruit stages; however, appressoria formation was less frequent on green fruit early in infection. Fungal penetration into the pericarp occurred 8 hours post-inoculation through cuticle wounds, with hyphae growing intercellularly among pericarp walls. By 24 hours post-inoculation, cell contents were disorganized, and cell walls had dissolved. In red fruit, vascular bundles were destroyed, whereas in green fruit, they remained intact. At 22°C, high levels of the mycotoxins altenuene, alternariol, and alternariol monomethyl ether were detected in both green and red infected fruit. The susceptibility of mature green fruit to black mold highlights the need for effective field treatments to prevent pathogen establishment and reduce postharvest disease.

Tree diseases associated with phytoplasma infections predominantly affecting nine host trees have serious impacts on tree growth and cause significant economic losses in South Korea. Loop-mediated isothermal amplification (LAMP)-based primers for early detection were developed to evaluate their accuracy. First, the 16S rRNA gene of phytoplasma was successfully amplified from the extracted DNA of various infected tree species using the polymerase chain reaction method. Two types diagnostic kits developed for phytoplasma detection were evaluated. The first kit detected phytoplasma infection within 30 min under isothermal conditions at 65°C, while the second kit did so within 40 min. Both kits could detect the nine different species of host trees infected with phytoplasma. When tested with 10 ng of the synthetic target gene, the FAM value became detectable at 10 min and remained consistent until 40 min. The lowest detection concentration was 0.01 pg/µL, and the limit of detection was 100 copies/µL. All of the phytoplasmas from nine diseased hosts were early detected. Furthermore, phytoplasma was not detected in healthy specimens, confirming the diagnostic kits' accuracy in distinguishing between healthy and infected strains. The LAMP method confirmed rapid, accurate, and visually assessable detection of phytoplasma, suggesting it will enable early diagnosis of phytoplasma infections in South Korea.

Chinese cabbage (Kimchi cabbage), an essential vegetable in Asian cuisine, faces significant threats from diseases such as Verticillium wilt, primarily caused by Verticillium longisporum and Verticillium dahliae. The Brassicaceae family, which includes Chinese cabbage, possesses unique botanical characteristics that distinguish it from other flowering plant families. Various methods, including morphological analysis and molecular techniques, have been utilized to identify Verticillium species. Recent advancements in detection methods, such as PCR-based techniques and genome sequencing, have improved our ability to accurately identify and differentiate these species. Understanding the genetic diversity and pathogenic mechanisms of Verticillium species is crucial for developing effective disease management strategies to protect Chinese cabbage production. This review explores the history, identification methods, and disease control approaches related to Verticillium infections in Chinese cabbage.

Bacterial panicle blight (BPB), caused by the aerobic Gram-negative bacterium Burkholderia glumae, poses a significant threat to global rice production. Cinnamon bark extract (CBE), rich in bioactive compounds such as eugenol and cinnamaldehyde, exhibits potent antioxidant and antimicrobial properties. To enhance the stability and efficacy of these volatile compounds, this study employed nanoencapsulation techniques. CBE-loaded nanoformulations were synthesized using the ionic coupling method between chitosan (CS) and trisodium phosphate (TPP) at varying TPP concentrations (0%, 0.5%, 1%, 2%, and 4%), resulting in CBE-CS nanoparticles. The nanoformulations were evaluated for antibacterial activity, chemical composition, and morphological characteristics. The antibacterial assays demonstrated inhibition zones ranging from 7.5 to 11.8 mm, with the 0.5% TPP formulation exhibiting the highest efficacy (minimum inhibitory concentration = 15.6 μmol/mL; minimum bactericidal concentration = 31.25 μmol/mL). Chemical analysis identified over 15 active compounds in CBE, with (Z)-3-phenylacrylaldehyde being the most abundant (34%). The nanoparticles had sizes ranging from 43.66 nm to 106.1 nm, encapsulation efficiencies of 48.65-48.78%, and loading capacities of 25.65-33.9%. Scanning electron microscopy revealed spherical, homogenous nanoparticles, while Fourier transform infrared and X-ray diffraction confirmed the successful encapsulation of CBE within CS nanoparticles. Microscopic examination revealed significant membrane damage in B. glumae cells treated with CBE-loaded nanoparticles compared to untreated controls. These findings underscore the potential of CBE-loaded CS nanoencapsulation as an effective, ecofriendly solution for managing BPB. The study highlights the promise of nanoencapsulation techniques in enhancing the stability and bioactivity of natural antimicrobial agents, offering a sustainable alternative to traditional chemical controls in agriculture.