Phylogenetic Diversity, Pathogenicity and Host Range of Verticillium longisporum and V. dahliae Associated with Verticillium Wilt of Chinese Cabbage in Korea.

Verticillium wilt is an emerging threat to Brassicaceae crops worldwide, yet information on the species diversity and pathogenicity of Verticillium on Napa cabbage (Brassica rapa subsp. pekinensis) in South Korea remains limited. During surveys in 2020 and 2021, patches of wilted Napa cabbage plants were observed in highland cultivation regions, with disease incidence ranging from 1 to 10%. Twenty symptomatic plants were collected, and fifteen fungal isolates were obtained through tissue culture. Morphological observations and multilocus phylogenetic analyses based on four loci (ACT, EF, GPD, and TS) identified two species, V. dahliae and Verticillium longisporum (lineages A1/D1). Morphologically, V. longisporum produced longer conidia (>6.1 μm) and elongate microsclerotia, whereas V. dahliae produced shorter conidia (<6.0 μm) and spherical microsclerotia. Growth assays demonstrated that V. longisporum grew optimally at 22 °C and V. dahliae at 25 °C, with V8 agar supporting the best growth of both species. Pathogenicity tests on Napa cabbage seedlings confirmed that both species caused typical wilt symptoms, including leaf yellowing, senescence, and stunted growth. To our knowledge, this is the first report of V. longisporum associated with Verticillium wilt of Napa cabbage in South Korea. While Verticillium wilt has so far been confined to highland cultivation areas, considering the predominance of V. longisporum in autumn–winter cropping regions in Japan, continued monitoring in similar Korean production regions will be essential. These findings provide new insights into the distribution, morphology, and pathogenicity of Verticillium species, contributing to the development of effective management strategies for Napa cabbage production.

Chinese cabbage (Brassica rapa L.) is one of the most important vegetables in Korea due to its role as the main ingredient for the making of Kimchi. In June 2014, disease symptoms of leaves wilt, dry, and drop off on Chinese cabbage were observed in a Chinese cabbage farm located at Taebeak (37°26'50.7"N 128°95'50.0"E), Gangwon province, Korea. This disease was observed on approximately 35% of the plants in the field, causing an almost 10% decrease in total production. At the early stage of infection, the color at the edge of the plant foliage changed from green to yellow. As the disease progressed, infected leaves wilted, dried off, and detached from the plant. Soft rot that occurred at the base of the leaf stem and root tissues caused the infected leaves to dry and fell off the plant. To identify the causal agent, a small piece of infected leaf tissues was sterilized with 1% sodium hypochlorite solution for 1 min and rinsed with sterile water before it was transferred onto potato dextrose agar (PDA) media. The plates were then incubated at 25°C for 10 days in the dark. Fungal colonies grown on PDA media were of white-creamy in color with an abundance of mycelia and later develop into black color due to the formation of microsclerotia embedded in the media. Microscopic examination showed conidiophores and phialides were both appeared in a verticillate arrangement, whereas conidia were hyaline, smooth-walled, and ellipsoidal to oval with average size 5.4×2.5 µm (n=100). Microsclerotia appeared in elongate to an irregularly spherical shape and greatly variable in size. The morphological attributes of the fungal isolate described above were comparable to the characteristics of Verticillium dahliae Kleb. (V. dahliae) described by Hawksworth and Talboys (1970), and V. dahliae isolated from Chinese cabbage in Japan reported in Kishi (1998). Pathogenicity test was performed by soaking twelve individual Chinese cabbage seedlings for 15 min into fungal pathogen conidial suspension (1x106 conidium/ml) before transferred into soil tray. The same number of non-inoculated seedlings on the soil tray was used as a control. Inoculated and control plants were then covered with a plastic bag for 24 hours to maintain high humidity before transferred into the greenhouse (25°C). Seven days post-inoculation (dpi), treated plant leaves turned yellow, and soft rot was observed. At 10-dpi, plant leaf tissues dried off and severe soft rot occurred. Pathogenicity test was repeated three times and consistent results were obtained. The re-isolated fungal pathogen from the inoculated plants showed identical morphological characteristics to the original isolates, thus fulfilling Koch's postulates. For further identification, PCR amplification targeting Internal Transcribed Spacer (ITS) and RNA polymerase II gene (RPB2) regions were performed (Liu et al., 1999; White et al., 1990). Each PCR product was sequenced and deposited in the GenBank under the accession LC549667 and LC061275, respectively. Sequence analysis using BLAST showed that the nucleotide sequences of ITS and RPB2 DNA fragments are 99-100% identical to the reference strain of V. dahliae available in the NCBI database (MG585719, HE972023, XM_009652520 and DQ522468, respectively). Therefore, based on the results of morphological and molecular analyses, the fungal pathogen isolated from Chinese cabbage in this study was identified as V. dahliae and deposited in the National Institute of Horticultural and Herbal Science germplasm collection (NIHHS 13-252). Recently, due to high demand and a more competitive price, more Chrysanthemum farmers in Korea switch their crops to Chinese cabbage. Interestingly, the occurrence of V. dahliae infection was also reported to occur in Chrysanthemum plants in Korea (Han et al. 2007), which indicates a serious problem ahead to these farmers. Therefore, in this current study, the identification of V. dahliae pathogenic to Chinese cabbage will provide vital knowledge for the development of disease management strategies to minimize the loss of crop production. To our knowledge, this is the first report that V. dahliae causes Verticillium wilt disease on Chinese cabbage in 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.

Fifteen Years of Verticillium Wilt of Lettuce in America's Salad Bowl: A Tale of Immigration, Subjugation, and Abatement.

Verticillium wilt on Chinese cabbage, caused by Verticillium dahliae and V. longisporum, is one of the most important soilborne plant diseases that is difficult to control and can greatly reduce production. We tested the extent to which treatment of mulch rows with dazomet, which is easy to handle compared with other common treatments, could reduce the incidence of Verticillium wilt on Chinese cabbage. We conducted eight trials in a total of four plots during 2020 to 2022. The results of each trial were analyzed using a generalized linear mixed model. In the model constructed with diseased plants versus healthy plants data as the objective variable, the regression coefficient of the treatment of dazomet on the untreated (reference) was −1.60. The dazomet treatment was effective ( P &lt; 0.01) in reducing Verticillium wilt incidence. Dazomet treatment inside mulch beds is highly practical as a new control technology for Verticillium wilt on Chinese cabbage because it has a large effect size, does not cause any chemical damage to Chinese cabbage, and is simple and labor-saving.

A tobamovirus, Ribgrass mosaic virus (RMV), was identified newly from chinese cabbage (Brassica campestris L. pekinensis) in Korea. Virus disease incidence of RMV on chinese cabbage was 37.9% in alpine area on August in 1993. RMV induced the symptoms of necrotic ring spots, necrotic streak on midrib and malformation. RMV, Ca1 and Ca3 isolate, could infect 35 species out of 45 plants including Chenopodium amaranticolor. Physical properties of RMV Ca1 isolate were very stable as 10.8 over for dilution end point, <TEX>$95^{\circ}C$</TEX> for temperature inactivation point and 18 weeks for longevity in vitro. RMV had the soil transmission rate of 75.0% for the chinese cabbages, 'Chunhawang' and 'Seoul' cultivars. The purified virions of RMV had the typical ultraviolet absorption spectrum of maximum at 260 nm and minimum at 247 nm. RMV of Ca1 isolate was related serologically with antisera of Tobacco mosaic virus (TMV)-Cym, TMV-O and Pepper mottle virus, but not related with antiserum of Odontoglossum ring spot virus. coat protein gene of RMV-Ca1, sized 473 nucleotides, encoded 158 amino acid residues. Nucleotide identity of RMV-Ca1 CP gene was 96.4% with RMV-Shanghai (GenBank accession No. of AF185272) from China and 96.0% with RMV-Impatiens (GenBank accession No. of AM040974) from Germany. Identity of amino acids between RMV-Ca1 and the two RMV isolates was 96.8%. Specific three primers were selected for rapid and easy genetic detection of RMV using Virion Captured (VC)/RT-PCR method.

With the development of sustainable agriculture, trials on the benefits of the application of organic fertilizers around the world have been conducted. Herein, we investigated the impact of the pure chemical fertilizers (CFs) combined with organic fertilizers compared with the application of CFs (100% CFs) and no fertilizers (NFs) on soil properties as well as the yield and quality of Chinese cabbage through meta-analysis. Results indicate that: (1) Compared with NFs, the application of organic fertilizers can significantly improve the yield and quality of Chinese cabbage and increase soil nutrients. (2) Compared with CFs, the application of organic fertilizers can increase the fresh weight, number of leaves, transverse diameter, leaf length, and development of Chinese cabbage per plant, with increases of 8.54%, 6.6%, 9.905%, 8.42%, and 10.03%; Meanwhile, organic fertilizers can significantly increase the yield (total amount of above-ground parts produced) and commercial yield (the portion that meets the required quality standards and is intended for sale) of Chinese cabbage to increase the yield and commercial yield by 10.08% and 35.56%, respectively. However, it has no significant impact on the income from growing Chinese cabbage. (3) Compared with CFs, the application of organic fertilizers can significantly increase the content of vitamin C (11.06%), soluble sugar (19.16%), and soluble protein (8.83%) and reduce the content of nitrate and nitrite in Chinese cabbage, with a reduction of up to 19.02% and 20.9%, respectively. The application of organic fertilizers will also have a certain impact on the absorption of heavy metals in Chinese cabbage. (4) Compared with CFs, the application of organic fertilizers can significantly improve soil organic matter, soil carbon sequestration, nitrogen absorption, and potassium absorption, showing increases of 12.73%, 13.19%, 7.91%, and 7.37%, and the application of organic fertilizers reduces soil electrical conductivity and available nitrogen, showing decreases of 36.78% and 38.75%, respectively. (5) The application of organic fertilizers significantly increased the content of soil urease and soil sucrase, increasing by 9.42% and 17.16%, respectively. This study helps inform the application of organic fertilizers in Chinese cabbage production.

Since Chinese cabbage is consumed fresh, its wholesale price varies with the total amount supplied on the market. However, in these days, climate variability presents a large threat to sustainable Chinese cabbage production in South Korea. To manage Chinese cabbage production well under unexpected weather conditions, it is important to study the impacts of climate variability on Chinese cabbage economic yields in South Korea. In this study, 2-year field trials were conducted in multiple locations across seven provinces in South Korea. The collected morphological data from 24 different varieties were used to develop a yield prediction model using a machine learning technique. Three Chinese cabbage groups were carried out through the clustering analysis, and a yield model was developed for each cluster group. The developed model was used to predict the cabbage economic yields under different combinations of climate change and cropping management plans. According to simulation results, Group 1 had the shortest growing degree days and produced higher yields than the other two groups. However, the overproduction of Group 1 led to a price reduction in the market of (USD(0.04–0.08) per kg), which suggested that producing Group 2 of (USD(0.31–0.96) per kg) is more beneficial to farmers. Based on the production results of the groups, their revenue varied by location and cropping management. The results of this study provide farmers with a better understanding of the relationship between production and economic benefits in future climate change scenarios.

Chinese cabbage yellows caused by Verticillium dahliae and V. longisporum is one of the most economically important diseases in Japan. Verticillium isolates from infected Chinese cabbage in Japan were identified as V. dahliae and V. longisporum based on morphological characteristics and newly developed molecular genotyping methods using group I intron of 18S rDNA, mitochondrial-SSU rDNA and cob gene. Although the two species were equally virulent to Chinese cabbage in the greenhouse, V. longisporum was more virulent in the field compared with V. dahliae. Among the 67 Verticillium isolates from Chinese cabbage, 53 were V. longisporum and considered to be the major pathogen. The isolation frequency of V. longisporum was 98 % in Ibaraki and eastern Gunma where Chinese cabbage was cropped from autumn to winter. In contrast, the frequency was 48 % in Nagano and north to west Gunma where the plant was cropped in cool summer and highland conditions and the rests were V. dahliae. This is the first report to show the different geographical distribution of V. longisporum and V. dahliae in Chinese cabbage production area of Japan.

Verticillium wilt greatly hampers Chinese cabbage growth, causing significant yield limitations. Rapid and accurate detection of Verticillium wilt in the Chinese cabbage (Brassica rapa L. ssp. pekinensis) can provide significant agronomic benefits. Here, we propose a detection model, DSConv-GAN, which is based on images acquired by an unmanned aerial vehicle (UAV). Based on YOLOv8, with the addition of the dynamic snake convolution (DSConv) module and the improved loss function maximum possible distance intersection-over-union (MPDIoU), we acquired enhanced complex structures and global characteristics in Chinese cabbage images under different growth conditions. To reduce the difficulty of acquiring diseased Chinese cabbage data, a cycle-consistent generative adversarial network (CycleGAN) was used to simulate and generate images of the Verticillium wilt characteristics for multiple fields. The detection of lightly infected plants achieved precision, recall, mean average precision (mAP), and F1-score of 81.3, 86.6, 87.7, and 83.9%, respectively. DSConv-GAN outperforms other models in terms of precision, detection speed, robustness, and generalization. The model is combined with software to improve the practicability of the proposed method. Our results demonstrate DSConv-GAN to be an effective intelligent farming tool that provides early, rapid, and accurate detection of Chinese cabbage Verticillium wilt in complex growing environments.

Purpose of the study: To explore the effects of adding different bacterial agents before fermentation on the Agricultural Jiaosu derived from waste from Chinese cabbage. Material and methods: This study used the waste from Chinese cabbage as the raw material and added Lactobacillus, Acetobacter, Yeast, and Bacillus subtilis respectively for fermentation treatment. Systematic research was conducted on the effects of different bacterial agents on the nutritional elements, microbial diversity, organic acid content of Agricultural Jiaosu, as well as their impacts on the growth and yield of Chinese cabbage. Results: The results showed that there were significant differences in the above aspects among the treatments with different bacterial agents. In terms of nutritional elements, the treatment group with Lactobacillus addition had the highest total carbon, total nitrogen, and total phosphorus contents; the treatment group with Acetobacter addition had the highest total potassium and carbon-nitrogen ratio. Microbial diversity analysis revealed that the relative abundance of Bacteroides was higher in the Lactobacillus treatment group; Arcobacter and Vishniacozyma were relatively more abundant in the Acetobacter and Bacillus subtilis treatment groups; and the relative abundance of Lysinibacillus was higher in the Yeast treatment group. Organic acid content analysis indicated that the benzoic acid content was higher in the Lactobacillus treatment group; the benzenepropanoic acid, azelaic acid, and pyroglutamic acid contents were higher in the Acetobacter treatment group; the succinic acid content was the highest in the Yeast treatment group; and the glutaric acid content was the highest in the Bacillus subtilis treatment group. Moreover, the effects of the Yeast and Acetobacter treatment groups on promoting the growth of Chinese cabbage were more significant. Conclusion and future prospective: In conclusion, Agricultural Jiaosu is rich in abundant nutritional elements, diverse microbial communities, and various organic acids, and has a significant fertilizer effect on Chinese cabbage production. Adding different bacterial agents before fermentation leads to differences in the composition and function of the finished Agricultural Jiaosu products. Therefore, appropriate bacterial agents can be selected for fermentation according to specific application goals to optimize the performance and application effect of Agricultural Jiaosu.

Chinese cabbage [Brassica rapa L. subsp. pekinensis (Lour.) Hanelt] has been grown commercially for many decades in Huade County, Inner Mongolia. In 2018 and 2019, an unusual stem and leaf wilt disease with an average disease incidence of approximately 3% was observed. Diseased plants with spindle-shaped stem lesions were collected and small pieces (0.3 × 0.3 cm) of the diseased tissues were cut from the margins of stem lesions, surface sterilized with 75% alcohol for 3 to 5 s, 0.1% NaClO for 2 to 3 min, and washed three times with sterilized water. The treated tissues were placed on 1.5% (w/v) water agar plates and incubated at 25°C for 3 days. The mycelia were cut and transferred onto potato dextrose agar (PDA) for culture purification. Three isolates with similar morphology were obtained and named as BC-2, BC3-2 and BG2. To confirm their pathogenicity, Chinese cabbage (cv. Chunqiuhuang) seed was planted into plugs. After 30 days, the fibrous roots were wounded with a fruit knife and root-dipped in the conidium suspension (1 × 106 conidia/ml) for 20 min. Inoculated seedlings were transplanted in pots (30 × 25 cm) with sterilized nursery soil, with one seeding per pot. The roots of control plants were also wounded and dipped in sterilized water. Five seedlings were inoculated with each isolate and the experiment was repeated three times. Treated seedlings were maintained in a greenhouse at 25 to 28°C under a 12-h photoperiod. Chlorosis and wilting were observed approximately 4 weeks after inoculation, and the outer layer of leaves of the inoculated seedlings developed discoloration and wilted symptoms after 50 days. The symptoms induced by all three isolates were the same as the symptoms observed in the field, whereas no symptoms developed on the control plants. To confirm the Koch's postulates, the fungus was successfully re-isolated from the infected leaves and had similar growth and morphology as the original isolates. The three isolates were cultured for both morphology and molecular identification. The 14-day-old colonies on PDA were buff or salmon pink with few aerial hyphae, and slimy surfaces. Aerial hyphae were sparse with simple or branched conidiophores. Conidia were ellipsoidal, hyaline, surface smooth, septate or aseptate, and (4.0 to 9.7 μm × 2.0 to 3.9 μm). Such characteristics are typical of Plectosphaerella spp. (Palm et al. 1995). For molecular identification, the internal transcribed spacer (ITS) region of rDNA was amplified using the primer pair ITS1/ITS4 (White et al. 1990), and the products were directly sequenced. BLAST analysis showed that the sequences of Isolates BC-2 (511 bp out of 515 bp), BC3-2 (512 bp out of 516 bp) and BG2 (503 bp out of 505 bp) showed 99% identity to an isolate of P. cucumerina (acc. no. KT826571.1) from Bottle gourd [Lagenaria siceraria (Molina) Standl.] (Yan et al. 2016). The sequences of Isolates BC-2, BC3-2 and BG2 were deposited in GenBank (acc. nos. MW320463, MW320462 and MW320464). Although P. cucumerina was reported causing root rot of cabbage (B. oleracea) in Gansu, China (Li et al. 2017), to our knowledge, this is the first report of P. cucumerina causing Chinese cabbage wilt in Inner Mongolia, China. The presence of the disease could cause significant economic losses in Chinese cabbage production. For this reason, strategies for the management and control of this disease should be implemented.

BackgroundTipburn, also known as leaf tip necrosis, is a severe issue in Chinese cabbage production. One known cause is that plants are unable to provide adequate Ca2+ to rapidly expanding leaves. Bacterial infection is also a contributing factor. Different cultivars have varying degrees of tolerance to tipburn. Two inbred lines of Chinese cabbage were employed as resources in this research.ResultsWe determined that the inbred line ‘J39290’ was the tipburn resistant material and the inbred line ‘J95822’ was the tipburn sensitive material based on the severity of tipburn, and the integrity of cell membrane structure. Ca2+ concentration measurements revealed no significant difference in Ca2+ concentration between the two materials inner leaves. Transcriptome sequencing technology was also used to find the differentially expressed genes (DEGs) of ‘J95822’ and ‘J39290’, and there was no significant difference in the previously reported Ca2+ uptake and transport related genes in the two materials. However, it is evident through DEG screening and classification that 23 genes are highly linked to plant-pathogen interactions, and they encode three different types of proteins: CaM/CML, Rboh, and CDPK. These 23 genes mainly function through Ca2+-CaM/CML-CDPK signal pathway based on KEGG pathway analysis, protein interaction prediction, and quantitative real-time PCR (qRT-PCR) of key genes.ConclusionsBy analyzing the Ca2+ concentration in the above two materials, the transcription of previously reported genes related to Ca2+ uptake and transport, the functional annotation and KEGG pathway of DEGs, it was found that Ca2+ deficiency was not the main cause of tipburn in ‘J95822’, but was probably caused by bacterial infection. This study lays a theoretical foundation for exploring the molecular mechanism of resistance to tipburn in Chinese cabbage, and has important guiding significance for genetics and breeding.

A new kind of postharvest rot on Chinese cabbage (Brassica rapa L. ssp. pekinensis) caused by a fungus was observed in vegetable cellars in Harbin, China in 2019 and 2020, causing considerable economic losses. A water-soaked spot appeared at the base of the midrib of leaves, extended into the upper part of the midrib, and ultimately turned into rot. The diseased part was dark brown or black with a few black spores on the surface. Fungal isolates were obtained from the diseased plants and identified as Aspergillus welwitschiae through morphological observation and multigene sequencing analysis of the internal transcribed spacer, β-tubulin and calmodulin genetic regions. Pathogenicity tests were conducted, and the resulting symptoms on Chinese cabbage were similar to those seen in the vegetable cellar. The isolates were also associated with rot and leaf spot on seedlings and affected the seed germination of Chinese cabbage. A host range test showed that the isolates could infect some common vegetables, including carrot, kidney bean, broccoli, radish, Chinese flowering cabbage, root-mustard, cabbage, non-heading Chinese cabbage, pepper, lettuce, oilseed rape, tomato and cucumber. The isolation, identification, and host range of the pathogen can provide a basis for the study of the occurrence, prevention and management of the disease in the future.

Water deficit or water excess can affect development and yield of vegetables. The objective of this study was to evaluate the effect of different soil water stress ranges for Chinese cabbage (Brassica pekinensis) in a protected cultivation. The researches were carried out at the Olericulture Sector of Universidade Federal Tecnologica do Paraná between April and July, 2015 and January and April, 2016. Two Chinese cabbage cultivars were analyzed (Eikoo and Kinjitsu) with four soil water stress range (13-17, 23-27, 33-37 and 43-47 kPa) moments of irrigation indicative parameters. The trial design was completely randomized, with four replications, in a factorial scheme. For head fresh mass, a soil stress range of 13-17 kPa resulted in higher yield (527.2 g/plant), in the first research. In the second one, ‘Eikoo’ showed higher productivity in the stress range 13-17 kPa (70.7 t ha-1). About water use efficiency, higher values were obtained, 42.1 kg m-³ in the first research and 47.3 kg m-³ in the second one with Kinjitsu and Eikoo cultivars, respectively, in the stress range 13-17 kPa. ‘Eikoo’ had a higher productivity than ‘Kinjitsu’ in the second research (summer), but in the first one (autumn-winter) these differences were not expressive. The use of stress ranges as indicative of irrigation return time between 13-17 kPa is suitable for Chinese cabbage crop.