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Infection by the mustard clubroot disease pathogen Plasmodiophora brassicae has a significant negative impact on the quality and yield of Chinese mustard (Brassica juncea). At present, screening resistant resources for breeding programs is the most economical and effective method available to control this disease. In this study, we isolated P. brassicae physiological race 4 from Chinese cabbage and examined 483 mustard germplasm resources (193 leaf mustard, 96 stem mustard, and 194 root mustard) from China and abroad to identify resistance to clubroot disease at the seedling stage through irrigation inoculation with the isolated pathogen. The results showed that there were no immune varieties among the tested mustard germplasm, but that there were differences in resistance to clubroot disease among the three mustard types. More than 90% of leaf and stem mustard resources were susceptible to clubroot disease, whereas 38.66% of root mustard resources showed resistance. In total, we detected 4 highly resistant, 9 resistant, and 83 moderately resistant varieties, of which 4 highly resistant, 8 resistant, and 63 moderately resistant varieties were root mustard resources, whereas only 1 resistant and 5 moderately resistant varieties were stem mustard resources, and 15 moderately resistant varieties were leaf mustard resources. In addition, we used seven molecular markers for clubroot disease resistance in Chinese cabbage to detect stem and root mustard resources. The results showed that the marker CRk was detected in 97.87% of stem mustard and 92.49% of root mustard resources. Six markers (Crr1, Crr2, Crr3, CRa, CRb, and CRc) were detected in 18.09%, 7.45%, 2.13%, 6.38%, 12.77%, and 12.77% of stem mustard germplasms, and four markers (Crr1, Crr2, Crr3, and CRc) were detected in 8.09%, 8.67%, 10.40%, and 8.67% of root mustard germplasms, respectively, suggesting that these markers are not suitable for detecting mustard germplasm resistance to clubroot disease. This study provides a technical reference and material support for the breeding of mustard varieties resistant to clubroot disease. [ABSTRACT FROM AUTHOR]

Plasmodiophora brassicae is a serious threat to Brassica crops worldwide, resulting in substantial economic losses for growers. Biocontrol with chitinolytic bacteria producing chitinase is gaining attention as a natural alternative to chemicals. This approach is favored due to the essential role chitinases play in protecting against chitin-containing pathogens. Given that chitin is a major component in the resting spores of P. brassicae and plays a crucial role during pathogenesis, it is probable that Paenibacillus chitinolyticus, producing a high level of chitinase, could suppress P. brassicae by targeting chitin in a critical stage of this pathogen's life cycle. Our research aimed to evaluate the effect of various applications of P. chitinolyticus on clubroot suppression in two economically important Brassica species: Chinese cabbage and rapeseed. The effectiveness of the cell-free supernatant (CFS) of an endemic strain of P. chitinolyticus from the Czech Republic at five different time points was studied in the greenhouse by measuring the disease severity index. Early application of P. chitinolyticus decreased the disease index significantly within both plant species resulting in increased shoot dry weight. In conclusion, the CFS of P.chitinolyticus has significant antagonistic activity against clubroot in Chinese cabbage and rapeseed in the early developmental stages of clubroot occurrence and holds the potential as a biofertilizer as well as bioprotectant agent in clubroot management of P. brassicae. [ABSTRACT FROM AUTHOR]

Abstract Aims: Straw turnover plays an important role in reducing soil diseases, improving the ecological environment of plowland and realizing the effective ecological utilization of straw. Methods: Pot and field experiments were carried out to investigate the effects of maize, rice and wheat straws on the growth, clubroot disease of Chinese cabbage and soil nutrients. Undecomposed and decomposed maize, rice and wheat straws were quantitatively added to the monocultural soil of Chinese cabbage, and the crops without straw were taken as the control. Results: The results showed that the addition of maize, wheat and rice straws could promote the growth of monocultural Chinese cabbage, inhibit the occurrence of clubroot disease, increase soil pH value, the content of soil organic matter, alkaline hydrolyzable nitrogen and available potassium in pot experiment. Exogenous straw application could reduce the incidence rate by 22.54 ~ 47.85%, increase the plot yield of field 95.15 ~ 365.81%. Conclusions: In terms of inhibiting clubroot disease and improving soil properties, undecomposed rice straw is superior to maize and wheat straw, while decomposed maize straw is superior to rice and wheat straw.

Clubroot disease, which is caused by the obligate biotrophic protist Plasmodiophora brassicae, leads to the formation of galls, commonly known as pathogen-induced tumors, on the roots of infected plants. The identification of crucial regulators of host tumor formation is essential to unravel the mechanisms underlying the proliferation and differentiation of P. brassicae within plant cells. To gain insight into this process, transcriptomic analysis was conducted to identify key genes associated with both primary and secondary infection of P. brassicae in Chinese cabbage. Our results demonstrate that the k-means clustering of subclass 1, which exhibited specific trends, was closely linked to the infection process of P. brassicae. Of the 1610 differentially expressed genes (DEGs) annotated in subclass 1, 782 were identified as transcription factors belonging to 49 transcription factor families, including bHLH, B3, NAC, MYB_related, WRKY, bZIP, C2H2, and ERF. In the primary infection, several genes, including the predicted Brassica rapa probable pectate lyase, RPM1-interacting protein 4-like, L-type lectin-domain-containing receptor kinase, G-type lectin S-receptor-like serine, B. rapa photosystem II 22 kDa protein, and MLP-like protein, showed significant upregulation. In the secondary infection stage, 45 of 50 overlapping DEGs were upregulated. These upregulated DEGs included the predicted B. rapa endoglucanase, long-chain acyl-CoA synthetase, WRKY transcription factor, NAC domain-containing protein, cell division control protein, auxin-induced protein, and protein variation in compound-triggered root growth response-like and xyloglucan glycosyltransferases. In both the primary and secondary infection stages, the DEGs were predicted to be Brassica rapa putative disease resistance proteins, Ltype lectin domain-containing receptor kinases, ferredoxin-NADP reductases, 1-aminocyclopropane-1-carboxylate synthases, histone deacetylases, UDPglycosyltransferases, putative glycerol-3-phosphate transporters, and chlorophyll a-binding proteins, which are closely associated with plant defense responses, biosynthetic processes, carbohydrate transport, and photosynthesis. This study revealed the pivotal role of transcription factors in the initiation of infection and establishment of intracellular parasitic relationships during the primary infection stage, as well as the proliferation and differentiation of the pathogenwithin the host cell during the secondary infection stage. [ABSTRACT FROM AUTHOR]

Clubroot disease poses a significant threat to Brassica crops, necessitating ongoing updates on resistance gene sources. In F2 segregants of the clubrootresistant inbred line BrT18-6-4-3 and susceptible DH line Y510, the genetic analysis identified a single dominant gene responsible for clubroot resistance. Through bulk segregant sequencing analysis and kompetitive allele-specific polymerase chain reaction assays, CRA8.1.6 was mapped within 110 kb (12,255-12,365 Mb) between markers L-CR11 and L-CR12 on chromosome A08. We identified BraA08g015220.3.5C as the candidate gene of CRA8.1.6. Upon comparison with the sequence of disease-resistant material BrT18-6-4-3, we found 249 single-nucleotide polymorphisms, seven insertions, six deletions, and a long terminal repeat (LTR) retrotransposon (5,310 bp) at 909 bp of the first intron. However, the LTR retrotransposon was absent in the coding sequence of the susceptible DH line Y510. Given the presence of a non-functional LTR insertion in other materials, it showed that the LTR insertion might not be associated with susceptibility. Sequence alignment analysis revealed that the fourth exon of the susceptible line harbored two deletions and an insertion, resulting in a frameshift mutation at 8,551 bp, leading to translation termination at the leucine-rich repeat domain's C-terminal in susceptible material. Sequence alignment of the CDS revealed a 99.4% similarity to Crr1a, which indicate that CRA8.1.6 is likely an allele of the Crr1a gene. Two functional markers, CRA08-InDel and CRA08-KASP1, have been developed for marker-assisted selection in CR turnip cultivars. Our findings could facilitate the development of clubrootresistance turnip cultivars through marker-assisted selection. [ABSTRACT FROM AUTHOR]

Straw return is an effective agricultural management practice for alleviating soil sickness, but only a few studies have focused on the incorporation of straw with deep plowing and rotary tillage practices in vegetable production. To determine the effects of rice straw return on Chinese cabbage clubroot, a field experiment for three consecutive years in the same area was performed. Soil microbial high-throughput sequencing, quantitative real-time polymerase chain reaction (PCR) and other methods were used to detect Chinese cabbage plant growth, clubroot occurrence, soil chemical properties and soil microbial diversity and abundance. The results showed that straw addition could significantly reduce the clubroot disease incidence. Through Illumina Miseq sequencing, the diversity of the fungi decreased obviously. The relative abundance of the phyla Proteobacteria and Firmicutes was strikingly reduced, while that of Chloroflexi was significantly increased. Redundancy analysis suggests that soil properties may also affect the soil microbial composition; changes in the microbial structure of bacteria and fungi were associated with the available phosphorus. In conclusion, the continuous addition of rice straw can promote the growth and control the occurrence of clubroot, which is closely related to the microbial composition, and the inhibition effect is proportional to the age of addition. [ABSTRACT FROM AUTHOR]

The soil-borne pathogen Plasmodiophora brassicae is the causal agent of clubroot, a major disease in Chinese cabbage (Brassica rapa ssp. pekinensis). The host's resistance genes often confer immunity to only specific pathotypes and may be rapidly overcome. Identification of novel clubroot resistance (CR) from germplasm sources is necessary. In this study, Bap246 was tested by being crossed with different highly susceptible B. rapa materials and showed recessive resistance to clubroot. An F2 population derived from Bap246 × Bac1344 was used to locate the resistance Quantitative Trait Loci (QTL) by Bulk Segregant Analysis Sequencing (BSA-Seq) and QTL mapping methods. Two QTL on chromosomes A01 (4.67–6.06 Mb) and A08 (10.42–11.43 Mb) were found and named Cr4Ba1.1 and Cr4Ba8.1, respectively. Fifteen and eleven SNP/InDel markers were used to narrow the target regions in the larger F2 population to 4.67–5.17 Mb (A01) and 10.70–10.84 Mb (A08), with 85 and 19 candidate genes, respectively. The phenotypic variation explained (PVE) of the two QTL were 30.97% and 8.65%, respectively. Combined with gene annotation, mutation site analysis, and real-time quantitative polymerase chain reaction (qRT-PCR) analysis, one candidate gene in A08 was identified, namely Bra020861. And an insertion and deletion (InDel) marker (co-segregated) named Crr1-196 was developed based on the gene sequence. Bra013275, Bra013299, Bra013336, Bra013339, Bra013341, and Bra013357 in A01 were the candidate genes that may confer clubroot resistance in Chinese cabbage. The resistance resource and the developed marker will be helpful in Brassica breeding programs. [ABSTRACT FROM AUTHOR]

Clubroot, caused by Plasmodiophora brassicae, is a destructive soil-borne disease significantly harming global Brassica crop production. This study employed the Williams and European Clubroot Differential (ECD) and Williams systems to identify the pathotypes of P. brassicae collected from Hangzhou City, Yuhang District and Quzhou City, Kaihua County in Zhejiang Province. Greenhouse and field trials were conducted to evaluate the effects of plastic film covering and four chemical agents on the growth parameters and clubroot severity of the Chinese cabbage cultivar 'Granaat'. Potential treatment mechanisms on clubroot were explored through a qPCR analysis of the resting spore density and pH measurement of the soil. Furthermore, treatment with 1-napthaleneacetic acid (NAA), a synthetic auxin, was also evaluated for its potential role in suppressing clubroot. The results indicate that the pathotypes of P. brassicae in the two districts were P1, ECD20/31/12, and P3, ECD20/15/4. While an individual application of plastic film covering could not effectively control clubroot, calcium cyanamid, dazomet and ammonium bicarbonate demonstrated significant efficacy in its management. These three agents significantly reduced the resting spore density in the soil, with calcium cyanamid and ammonium bicarbonate also increasing soil alkalinity. Additionally, ammonium bicarbonate promotes lateral root development in 'Granaat,' helping infected plants access adequate water and nutrients. However, NAA exhibited no efficacy in clubroot control. Therefore, sustained lateral root development is crucial for effectively resisting P. brassicae invasion. Considering application costs and environmental friendliness, we propose the field application of ammonium bicarbonate as the optimal method for clubroot disease management in Zhejiang Province. [ABSTRACT FROM AUTHOR]

Chinese cabbage is an economically important Brassica vegetable worldwide, and clubroot, which is caused by the soil-borne protist plant pathogen Plasmodiophora brassicae is regarded as a destructive disease to Brassica crops. Previous studies on the gene transcripts related to Chinese cabbage resistance to clubroot mainly employed RNA-seq technology, although it cannot provide accurate transcript assembly and structural information. In this study, PacBio RS II SMRT sequencing was used to generate full-length transcriptomes of mixed roots at 0, 2, 5, 8, 13, and 22 days after P. brassicae infection in the clubroot-resistant line DH40R. Overall, 39 376 high-quality isoforms and 26 270 open reading frames (ORFs) were identified from the SMRT sequencing data. Additionally, 426 annotated long noncoding RNAs (lncRNAs), 56 transcription factor (TF) families, 1 883 genes with poly(A) sites and 1 691 alternative splicing (AS) events were identified. Furthermore, 1 201 of the genes had at least one AS event in DH40R. A comparison with RNA-seq data revealed six differentially expressed AS genes (one for disease resistance and five for defensive response) that are potentially involved in P. brassicae resistance. The results of this study provide valuable resources for basic research on clubroot resistance in Chinese cabbage.

Clubroot disease has spread explosively in recent years, posing a serious threat to cruciferous crop production. Take rapeseed for example, according to the statistics, until year 2022 the incidence of the clubroot has exceeded 1.33 million hectares in China. Breeding for resistant cultivars is considered as the most efficient and economical way to prevent clubroot disease spreading. However, the current CR cultivars mostly used CR loci of PbBa8.1 or CRb. Due to the complexity and diversity of Plasmodiophora brassicae from different locations, resources for resistant germplasm need to be explored. In this study, 14 clubroot-resistant Chinese cabbages were characterized using different clubroot pathogens and molecular markers for known CR loci. We found that among them, five materials, DG117, ZS105, SG01, SR06 and JQ07 did not contain CRb locus, and their disease resistance were stronger than Huashuang5R/Huayouza5R. At last, KL02 containing the CRb locus showed stronger resistance to PbXM (strain from Xinmin) than 409R, therefore it may contain other novel loci leading to better resistance. These six Chinese cabbage resources can be considerd as new resistance resources and could be utilized in future breeding work for CR Brassica napus. [ABSTRACT FROM AUTHOR]

Relevance and purpose of the study. Chinese cabbage is a vegetable crop with a high content of vitamins and low calorie content, valued for its ability to receive several crops per year and high productivity. Recently, there has been a reduction in the supply of the vegetable to Russia. There are less than 70 varieties and hybrids of the crop in the State Register of Selection Achievements, many of them are susceptible to the most important diseases. It is necessary to meet consumer demand with new commercial hybrids with resistance to stressors. The aim of the study was to evaluate and obtain genotypes with a set of valuable economic traits, including resistance to clubroot, powdery mildew, and early bolting.Materials and methods. The Chinese cabbage lines of various degrees of inbred and DH, as well as hybrid combinations from crossing these lines, were used as plant material. The lines were obtained in 2019-2020, the breeding material for them was selected on the ground infected with clubroot and with tolerance to tip burn of heads. To achieve the goal, the following methods were applied: plants cultivation; DNA isolation (CTAB method); PCR analysis; electrophoresis and visualization of results; productivity assessment and dispersion analysis; obtaining doubled haploids in culture of isolated microspores in vitro, assessment of resistance/susceptibility to powdery mildew.Results. 2 genotypes with high productivity and alignment in turnover summer-autumn 2022 and a genotype exceeding 3 standards in head weight in turnover spring-summer 2022 were recommended; as a result of molecular genotyping, 41 lines were differentiated according to the clubroot resistance gene CRb; DH plants for 4 genotypes with resistance to early bolting were obtained, their responsiveness to embryogenesis was studied; 18 lines were evaluated for resistance to powdery mildew, 7 genotypes with resistance to the disease were identified.

Cabbage production is promoted as a cash crop for small-land holders to support poverty alleviation on the Bolaven Plateau in Champasak Province, Lao People's Democratic Republic (PDR). A stunted cabbage crop in Paksong was inspected due to a near total yield loss. Examination of the root systems revealed the presence of enlarged roots. Subsequently the disease was found in another round-head cabbage crop, and in a Chinese cabbage crop in a polyhouse. Air-dried clubroot specimens were forwarded to Australia where molecular methods confirmed the presence of Plasmodiophora brassicae. This is the first report of the obligate pathogen Plasmodiophora brassicae in the Lao PDR. [ABSTRACT FROM AUTHOR]

Straw return is an effective agricultural management practice for alleviating soil sickness, but only a few studies have focused on the incorporation of straw with deep plowing and rotary tillage practices in vegetable production. To determine the effects of rice straw return on Chinese cabbage clubroot, a field experiment for three consecutive years in the same area was performed. Soil microbial high-throughput sequencing, quantitative real-time polymerase chain reaction (PCR) and other methods were used to detect Chinese cabbage plant growth, clubroot occurrence, soil chemical properties and soil microbial diversity and abundance. The results showed that straw addition could significantly reduce the clubroot disease incidence. Through Illumina Miseq sequencing, the diversity of the fungi decreased obviously. The relative abundance of the phyla Proteobacteria and Firmicutes was strikingly reduced, while that of Chloroflexi was significantly increased. Redundancy analysis suggests that soil properties may also affect the soil microbial composition; changes in the microbial structure of bacteria and fungi were associated with the available phosphorus. In conclusion, the continuous addition of rice straw can promote the growth and control the occurrence of clubroot, which is closely related to the microbial composition, and the inhibition effect is proportional to the age of addition.

Clubroot is a soil-borne disease caused by Plasmodiophora brassicae, which can seriously affect the growth and production of cruciferous crops, especially Chinese cabbage crops, worldwide. At present, few studies have been conducted on the molecular mechanism of this disease's resistance response. In this experiment, we analyzed the bioinformation of bra-miR167a, constructed a silencing vector (STTM167a) and an overexpression vector (OE-miR167a), and transformed them to Arabidopsis to confirm the role of miR167a in the clubroot resistance mechanism of Arabidopsis. Afterwards, phenotype analysis and expression level analysis of key genes were conducted on transgenic plants. From the result, we found that the length and number of lateral roots of silence transgenic Arabidopsis STTM167a was higher than that of WT and OE-miR167a. In addition, the STTM167a transgenic Arabidopsis induced up-regulation of disease resistance-related genes (PR1, PR5, MPK3, and MPK6) at 3 days after inoculation. On the other hand, the auxin pathway genes (TIR1, AFB2, and AFB3), which are involved in maintaining the balance of auxin/IAA and auxin response factor (ARF), were down-regulated. These results indicate that bra-miR167a is negative to the development of lateral roots and auxins, but positive to the expression of resistance-related genes. This also means that the STTM167a can improve the resistance of clubroot by promoting lateral root development and the level of auxin, and can induce resistance-related genes by regulating its target genes. We found a positive correlation between miR167a and clubroot disease, which is a new clue for the prevention and treatment of clubroot disease. [ABSTRACT FROM AUTHOR]

Straw incorporation is known as an environmentally friendly agricultural practice that can effectively enhance soil nutrient contents and crop yields; its potential to suppress soil-borne disease has also been reported in recent years. Here, we perform a field experiment for two consecutive years (2017–2018) to evaluate the effectiveness of maize (Zea mays), rice (Oryzae sativa L.) and wheat (Triticum aestivum L.) straws incorporation in alleviating Chinese cabbage (Brassica rapa L. ssp. pekinensis) clubroot disease caused by Plasmodiophora brassicae Woronin. Microbial composition in Chinese cabbage rhizosphere and soil P. brassicae abundance were estimated by high-throughput amplicon sequencing and quantitative polymerase chain reaction (qPCR). Results showed that, during the two-year field experimental cycle, all three straw amendments promoted Chinese cabbage plant growth, inhibited clubroot disease and increased the alpha diversity of the bacterial community in Chinese cabbage rhizosphere. Rice and wheat straws also increased the alpha diversity of the fungal community. These straws diversified the composition of the Chinese cabbage rhizosphere microbial community. All three straws promoted Cryptococcus carnescens; both rice and wheat straws stimulated Lysobacter sp.; maize straw boosted Sphingomonas sp. and wheat straw increased Talaromyces sp. These microbial taxa are either considered to have positive influences on plant growth or potential biocontrol effects. In addition, straw amendments also increased soil pH, electrical conductivity, available nitrogen and available potassium contents in both years of the field experiment. Taken together, we concluded that these three gramineous straw amendments ameliorated Chinese cabbage rhizosphere microorganisms, inhibited clubroot disease and promoted the growth of Chinese cabbage, and that rice straw worked best amongst the three. This study could potentially provide a new tactic of massive grain crop straw utilization and a direction in dealing with clubroot disease. [ABSTRACT FROM AUTHOR]

Clubroot disease is a soil-borne disease caused by Plasmodiophora brassicae that leads to a serious yield reduction in cruciferous plants. In this study, ergothioneine (EGT) was used to culture P. brassicae resting spores, the germination of which was significantly inhibited. Further exogenous application of EGT and P. brassicae inoculation in Chinese cabbage showed that EGT promoted root growth and significantly reduced the incidence rate and disease index. To further explore the mechanism by which EGT improves the resistance of Chinese cabbage to clubroot, a Chinese cabbage inbred line BJN3-2 susceptible to clubroot treated with EGT was inoculated, and a transcriptome analysis was conducted. The transcriptome sequencing analysis showed that the differentially expressed genes induced by EGT were significantly enriched in the phenylpropanoid biosynthetic pathway, and the genes encoding related enzymes involved in lignin synthesis were upregulated. qRT-PCR, peroxidase activity, lignin and flavonoid content determination showed that EGT promoted the lignin and flavonoid synthesis of Chinese cabbage and improved its resistance to clubroot. This study provides a new insight for the comprehensive prevention and control of cruciferous clubroot and for further study of the effects of EGT on clubroot disease. [ABSTRACT FROM AUTHOR]

Trehalose is a nonreducing disaccharide that is widely distributed in various organisms. Trehalose-6-phosphate synthase (TPS) is a critical enzyme responsible for the biosynthesis of trehalose, which serves important functions in growth and development, defense, and stress resistance. Although previous studies have found that the clubroot pathogen Plasmodiophora brassicae can lead to the accumulation of trehalose in infected Arabidopsis organs, it has been proposed that much of the accumulated trehalose is derived from the pathogen. At present, there is very little evidence to verify this view. In this study, a comprehensive analysis of the TPS gene family was conducted in Brassica rapa and Plasmodiophora brassicae. A total of 14 Brassica rapa TPS genes (BrTPSs) and 3 P. brassicae TPS genes (PbTPSs) were identified, and the evolutionary characteristics, functional classification, and expression patterns were analyzed. Fourteen BrTPS genes were classified into two distinct classes according to phylogeny and gene structure. Three PbTPSs showed no significant differences in gene structure and protein conserved motifs. However, evolutionary analysis showed that the PbTPS2 gene failed to cluster with PbTPS1 and PbTPS3. Furthermore, cis-acting elements related to growth and development, defense and stress responsiveness, and hormone responsiveness were predicted in the promoter region of the BrTPS genes. Expression analysis of most BrTPS genes at five stages after P. brassicae interaction found no significant induction. Instead, the expression of the PbTPS genes of P. brassicae was upregulated, which was consistent with the period of trehalose accumulation. This study deepens our understanding of the function and evolution of BrTPSs and PbTPSs. Simultaneously, clarifying the biosynthesis of trehalose in the interaction between Brassica rapa and P. brassicae is also of great significance. [ABSTRACT FROM AUTHOR]

Key message: In this study, we fine-mapped a clubroot resistance gene CRA3.7 in Chinese cabbage and developed its closely linked marker syau-InDel3008 for marker-assisted selection in CR cultivars breeding. Chinese cabbage is an important leafy vegetable rich in many nutrients widely grown in China. Clubroot disease caused by an obligate biotrophic pathogen Plasmodiophora brassicae was rapidly spread and challenged to Chinese cabbage production. A clubroot resistance (CR) gene, CRA3.7, was mapped on chromosome A03 of Brassica rapa. A Chinese cabbage line 'CR510', which harbor homozygous resistance locus CRA3.7 was selected from a BC4F3 family. 'CR510' was crossed with a clubroot susceptible Chinese cabbage inbred line '59-1'. Total 51 recombinant plants were identified from an F2 population including 3000 individuals. These recombinants were selfed and the clubroot resistance of F2/3 families was evaluated. Finally, a clubroot resistance gene CRA3.7 was fine-mapped to an interval of approximately 386 kb between marker syau-InDel3024 and syau-InDel3008. According to the reference genome, total 54 genes including five encoding the TIR-NBS-LRR proteins was annotated in the fine-mapped region. Further, nine candidate's gene expression in parental lines at 7, 14 and 21 days after inoculation of P. brassicae were evaluated. Bra019376, Bra019401, Bra019403 and Bra019410 are highly expressed in 'CR510' than '59-1'. Gene sequence of Bra019410 from 'CR510' was cloned and identified different from CRa. Therefore, Bra019376, Bra019401, Bra019403 and Bra019410 are the most likely candidates for CRA3.7. Our research provides a valuable germplasm resource against P. brassicae Pb3 and CRA3.7 closely linked marker for marker-assisted selection in CR cultivars breeding. [ABSTRACT FROM AUTHOR]

Clubroot, caused by Plasmodiophora brassicae, is an economically important soil-borne disease that threatens Brassicaceae crops worldwide. In recent years, the incidence area of Chinese cabbage (Brassica rapa ssp. pekinensis) clubroot disease has increased, which severely affects the yield and quality of Chinese cabbage. The resistance of varieties harboring the single clubroot-resistance (CR) gene is easily broken through by P. brassicae pathotypes. CRa and CRd, genetically identified in B. rapa, are CR genes known to be highly resistant to different P. brassicaea pathotypes. In our study, we perform the gene pyramiding of CRa and CRd in Chinese cabbages through marker-assisted selection (MAS), and develop homozygous pyramided lines. The newly generated pyramided lines exhibit greater resistance to six different pathotypes than that of two parental lines carrying a single CR gene. This study provides new CR-gene-pyramided lines for the development of clubroot-resistant Brassica varieties for future breeding programs. [ABSTRACT FROM AUTHOR]

Clubroot is a soil-borne disease of cruciferous crops, including Brassica rapa ssp. pekinensis, and causes substantial yield losses. In an attempt to develop clubroot-resistant B. rapa cultivars, we investigated the role of a root-abundant expansin-like B1 (EXLB1) during Plasmodiophora brassicae inoculation. The histochemical analyses of infected transgenic reporter lines showed a role for BrEXLB1 in disease response as early as 3 dpi. The transgenic overexpression of EXLB1 in B. rapa conferred disease-sensitive phenotypes and was comparable to non-transgenic controls at 30 dpi. In contrast, the heterogeneous population of antisense BrEXLB1-overexpressing lines conferred disease resistance against highly pathogenic P. brassicae race 2 inoculations under greenhouse conditions. Additionally, we profiled the relative expression of 32 other BrEXPs in wild-type seedlings, sampled on different days (1–10) after inoculation using qRT-PCR. The results indicate that the expression pattern of most BrEXP genes was significantly altered during different infection times, suggesting their participation in clubroot responses. In particular, the expressions of EXPA20, EXPA21, and EXPA34 were consistently downregulated, while the expression of EXPA5 was upregulated (log2FC ≥ 2) compared to controls. Altogether, our study showed that BrEXPs participate in clubroot disease response, and their genetic manipulation is likely to provide clubroot disease resistance. [ABSTRACT FROM AUTHOR]

Summary: Clubroot is one of the most important diseases for many important cruciferous vegetables and oilseed crops worldwide. Different clubroot resistance (CR) loci have been identified from only limited species in Brassica, making it difficult to compare and utilize these loci. European fodder turnip ECD04 is considered one of the most valuable resources for CR breeding. To explore the genetic and evolutionary basis of CR in ECD04, we sequenced the genome of ECD04 using de novo assembly and identified 978 candidate R genes. Subsequently, the 28 published CR loci were physically mapped to 15 loci in the ECD04 genome, including 62 candidate CR genes. Among them, two CR genes, CRA3.7.1 and CRA8.2.4, were functionally validated. Phylogenetic analysis revealed that CRA3.7.1 and CRA8.2.4 originated from a common ancestor before the whole‐genome triplication (WGT) event. In clubroot susceptible Brassica species, CR‐gene homologues were affected by transposable element (TE) insertion, resulting in the loss of CR function. It can be concluded that the current functional CR genes in Brassica rapa and non‐functional CR genes in other Brassica species were derived from a common ancestral gene before WGT. Finally, a hypothesis for CR gene evolution is proposed for further discussion. [ABSTRACT FROM AUTHOR]

Clubroot is a soil-borne disease caused by Plasmodiophora brassicae, which can seriously affect the growth and production of cruciferous crops, especially Chinese cabbage crops, worldwide. At present, few studies have been conducted on the molecular mechanism of this disease’s resistance response. In this experiment, we analyzed the bioinformation of bra-miR167a, constructed a silencing vector (STTM167a) and an overexpression vector (OE-miR167a), and transformed them to Arabidopsis to confirm the role of miR167a in the clubroot resistance mechanism of Arabidopsis. Afterwards, phenotype analysis and expression level analysis of key genes were conducted on transgenic plants. From the result, we found that the length and number of lateral roots of silence transgenic Arabidopsis STTM167a was higher than that of WT and OE-miR167a. In addition, the STTM167a transgenic Arabidopsis induced up-regulation of disease resistance-related genes (PR1, PR5, MPK3, and MPK6) at 3 days after inoculation. On the other hand, the auxin pathway genes (TIR1, AFB2, and AFB3), which are involved in maintaining the balance of auxin/IAA and auxin response factor (ARF), were down-regulated. These results indicate that bra-miR167a is negative to the development of lateral roots and auxins, but positive to the expression of resistance-related genes. This also means that the STTM167a can improve the resistance of clubroot by promoting lateral root development and the level of auxin, and can induce resistance-related genes by regulating its target genes. We found a positive correlation between miR167a and clubroot disease, which is a new clue for the prevention and treatment of clubroot disease.

Clubroot disease is a common soilborne disease caused by Plasmodiophora brassicas Wor. and widely occurs in Chinese cabbage. Soil microorganisms play vital roles in the occurrence and development of plant diseases. The changes in the soil bacterial community could indicate the severity of plant disease and provide the basis for its control. This study focused on the bacterial community of the clubroot disease-infected soil--root system with different severity aiming to reveal the composition and structure of soil bacteria and identified potential biomarker bacteria of the clubroot disease. In the clubroot disease-infected soil, the bacterial community is mainly composed of Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, Bacilli, Thermolrophilia, Bacteroidia, Gemmatimonadetes, Subgroup_6, Deltaproteobacteria, KD4-96, and some other classes, while the major bacterial classes in the infected roots were Oxyphotobacteria, Gammaproteobacteria, Alphaproteobacteria, Actinobacteria, Bacilli, Bacteroidia, Saccharimonadia, Thermoleophilia, Clostridia, Chloroflexia, and some other classes. The severe clubroot disease soil--root system was found to possess a poorer bacterial richness, evenness, and better coverage. Additionally, a significant difference was observed in the structure of the bacterial community between the high-severity (HR) and healthy (LR) soil--root system. Bacillus asahii and Noccaea caerulescens were identified as the differential bacteria between the LR and HR soil and roots, respectively. pH was demonstrated as a vital factor that was significantly associated with the abundance of B. asahii and N. caerulescens. This study provides novel insight into the relationship between soil bacteria and the pathogen of clubroot disease in Chinese cabbage. The identification of resistant species provides candidates for the monitoring and biocontrol of the clubroot disease. [ABSTRACT FROM AUTHOR]

Background: CRa is a key gene in Chinese cabbage (Brassica rapa ssp. pekinensis) that confers resistance to Plasmodiophora brassicae. In order to efficiently screen the clubroot resistance (CR) gene CRa in breeding, two functional codominant markers of the CRa gene were developed. Methods and results: In this study, through comparing the CRa allele sequences in resistant and susceptible cultivars of Chinese cabbage, we found two insertion and deletion of sequence variations in the fourth exon between resistant and susceptible cultivars. Two functional codominant markers for CRa gene were obtained based on the variations, namely, CRaEX04-1 and CRaEX04-3. The lengths of the extended fragment of CRaEX04-1 marker were 321 bp and 186 bp in resistant and susceptible cultivars, respectively. In contrast, those of CRaEX04-3 were 704 bp and 413 bp, respectively. We verified the genetic stability between the developed markers and CRa gene using 57 Chinese cabbage cultivars with known resistance and two genetic populations. The results showed that the marker identification was completely consistent with the known phenotypes in 57 cultivars. The marker identification results followed the 3:1 of Mendel's first law in the F2 population, and the 1:1 of Mendel's first law in the BC1. Conclusions: CRaEX04-1 and CRaEX04-3 can be used as a practical molecular marker for breeding and germplasm resource creation of clubroot disease-resistant Chinese cabbage. [ABSTRACT FROM AUTHOR]

Simple Summary: Clubroot, caused by Plasmodiophora brassicae Woron, seriously affects cruciferous plants. The pathogen survives in the soil in the form of resting spores and infects crops for many generations. Currently, clubroot management relies on pesticides and resistant varieties with several limitations. Therefore, there is a need to devise environmentally friendly control measures to mitigate this devastating pathogen. The occurrence and damage of clubroot can be alleviated by microbial consortia. The biocontrol potential of Bacillus cereus BT-23, Lysobacter antibioticus 13-6, and Lysobacter capsici ZST1-2 was investigated as sole strains, intra-/inter-genus co-cultures, and microbial consortia for clubroot disease, plant growth, and rhizosphere bacterial diversity in a field experiment. The microbial consortia efficiently controlled the disease incidence with a successful biocontrol effect of about 65.78%, reshaped the rhizosphere's microbial diversity, and reduced the soil acidity. Thus, we conclude that microbial consortia suppress the disease incidence by recovering the imbalance in the indigenous microbial community composition. This study highlights the potential of microbial consortia as an engineering tool to control soilborne diseases by reshaping the rhizosphere microbiome. Clubroot disease, caused by Plasmodiophora brassicae, is a serious threat to Chinese cabbage (Brassica rapa subsp. pekinensis) production, which results in extensive yield losses. At present, clubroot control mainly depends upon pesticides, which provoke food-safety concerns, and the application of sole biocontrol agents cannot successfully control the disease. In this study, we investigated the effect of Bacillus cereus BT-23, Lysobacter antibioticus 13-6, and Lysobacter capsici ZST1-2 as sole strains, intra-/inter-genus co-culture, and microbial consortia on clubroot disease, plant growth, and rhizosphere bacterial diversity in a field experiment. The microbial consortia efficiently controlled the incidence of clubroot disease, with a biocontrol effect of about 65.78%, by decreasing the soil acidity and enhancing the yield (17,662.49 kg/acre). The high-throughput sequencing results demonstrated that the phyla Proteobacteria and Bacteroidetes were present in high relative abundance in the rhizosphere soil of the Chinese cabbage. Furthermore, Firmicutes was found as a unique phylum in the rhizosphere soil of CK-H and T1-T7, except for CK-D. The application of microbial consortia recovers the imbalance in indigenous microbial communities. Therefore, we conclude that microbial consortia can reduce the clubroot incidence in Chinese cabbage by decreasing the soil acidity and altering the diversity and structure of rhizosphere bacterial communities. This study highlights the potential of microbial consortia as an engineering tool to control devastating soilborne diseases in commercial crops. [ABSTRACT FROM AUTHOR]

Plasmodiophora brassicae is a soil-borne pathogen that attacks the roots of cruciferous plants and causes clubroot disease. CircRNAs are noncoding RNAs, widely existing in plant and animal species. Although knowledge of circRNAs has been updated continuously and rapidly, information about circRNAs in the regulation of clubroot disease resistance is extremely limited in Brassica rapa. Here, Chinese cabbage (BJN 222) containing clubroot resistance genes (CRa) against P. brassicae Pb4 was susceptible to PbE. To investigate the mechanism of cicRNAs responsible for clubroot disease resistance in B. rapa, circRNA-seq was performed with roots of 'BJN 222' at 0, 8, and 23 days post-inoculated (dpi) with Pb4 and PbE. A total of 231 differentially expressed circRNAs were identified between the groups. Based on the differentially expressed circRNAs, the circRNA–miRNA–mRNA network was constructed using the target genes directly or indirectly related to plant resistance. Upregulated novel_circ_000495 suppressed the expression of miR5656-y, leading to the upregulation of Bra026508, which might cause plant resistance. Our results provide new insights into clubroot resistance mechanisms and lay a foundation for further studies exploring complex gene regulation networks in B. rapa. [ABSTRACT FROM AUTHOR]

Clubroot is caused by Plasmodiophora brassicae , which threatens Brassicaceae crop production worldwide. In recent years, there has been an outbreak and rapid spread of clubroot in many major cruciferous crop-producing areas of China. In this study, we identified a cabbage material DingWen (DW) with different resistant capabilities from Huashuang5R (H5R) and Huayouza62R of Brassica napus , which are currently used as the main resistant cultivars for clubroot management in China. We used a next-generation sequencing-based bulked segregant analysis approach, combined with genetic mapping to identify clubroot-resistant (CR) genes from F1 population generated from a cross between the DW (CR) and HZSX (clubroot susceptible). The CR locus of DW (named CRA8.1) was mapped to a region between markers A08-4346 and A08-4853, which contains two different loci CRA8.1a and CRA8.1b after fine mapping. The CRA8.1b loci contain a fragment of 395 kb between markers A08-4624 and A08-4853 on A08 chromosome, and it is responsible for the resistance to PbZj and PbXm isolates. However, together with CRA8.1a , corresponding to a 765-kb region between markers A08-4346 and A08-4624, then it can confer resistance to PbXm +. Finally, through expression analysis between resistant and susceptible materials, two genes encoding TIR-NBS-LRR proteins (BraA08g039211E and BraA08g039212E) and one gene encoding an RLP protein (BraA08g039193E) were identified to be the most likely CR candidates for the peculiar resistance in DW. [ABSTRACT FROM AUTHOR]

Clubroot disease caused by Plasmodiophora brassicae is one of the major threats to Brassica crops. New clubroot resistant varieties of Chinese cabbage (B. rapa ssp. pekinensis) have been developed through breeding, but the underlying genetic mechanism of clubroot resistance is still unclear. In this study, two Chinese cabbage DH lines, clubroot-resistant Y635-10 and susceptible Y177-47 were crossed to develop F2 population for fine mapping and cloning resistance gene CRq. After sequence analysis, the expression vector was constructed by gateway technology and transferred into Arabidopsis thaliana for functional characterization. Bulked segregant analysis sequencing (BSA-seq) confirmed that CRq is located in the 80 kb genomic region on chromosome A03 between markers GC30-FW/RV and BGA. In silico tools confirmed that the gene length was 3959 bp with 3675 bp coding sequences (CDs), and it has three exons and two introns. In addition, we found 72bp insertion in the third exon of CRq in the susceptible line. We developed and verified functional marker Br-insert1, by which genotyping results showed that 72bp insertion might lead to the destruction of the LRR region of Y177-47, resulting in a loss of resistance relative to clubroot. The results of genetic transformation showed that the roots for wild-type Arabidopsis thaliana were significantly enlarged compared with T2 generation transgenic Arabidopsis after treatment by P. brassicae spores, and transgenic Arabidopsis had certain resistance. Therefore, CRq is a candidate gene of clubroot disease resistance in Chinese cabbage, which could be used as a reference for elucidating disease resistance mechanisms and the marker-assisted breeding of clubroot resistant varieties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plasmodiophora brassicae manipulates host sugar transporters. • BrSWEET genes up-regulate in Chinese cabbage upon plasmodiophora brassicae infection. • Functional analysis reveals BrSWEET genes' role in sugar transport and clubroot disease susceptibility. • BrSWEET1a , BrSWEET11a , BrSWEET12a identified as key genes in response to P. brassicae. Plasmodiophora brassicae , the causative agent of clubroot disease, establishes a long-lasting parasitic relationship with its host by inducing the expression of sugar transporters. Previous studies have indicated that most BrSWEET genes in Chinese cabbage are up-regulated upon infection with P. brassicae. However, the key BrSWEET genes responsive to P. brassicae have not been definitively identified. In this study, we selected five BrSWEET genes and conducted a functional analysis of them. These five BrSWEET genes showed a notable up-regulation in roots after P. brassicae inoculation. Furthermore, these BrSWEET proteins were localized to the plasma membrane. Yeast functional complementation assays confirmed transport activity for glucose, fructose, or sucrose in four BrSWEETs, with the exception of BrSWEET2a. Mutants and silenced plants of BrSWEET1a , - 11a , and - 12a showed lower clubroot disease severity compared to wild-type plants, while gain-of-function Arabidopsis thaliana plants overexpressing these three BrSWEET genes exhibited significantly higher disease incidence and severity. Our findings suggested that BrSWEET1a , BrSWEET11a , and BrSWEET12a play pivotal roles in P. brassicae -induced gall formation, shedding light on the role of sugar transporters in host-pathogen interactions. [ABSTRACT FROM AUTHOR]

Crop rotation can improve soil properties and is one of the important measures to prevent soil-borne diseases. This study aimed to evaluate the effects of different preceding crops on clubroot disease in Chinese cabbage and soil microorganisms, to provide a theoretical basis for the ecological control of clubroot scientifically. In this experiment, soybeans, potato onions, and wheat were used as the preceding crops and compared with the local preceding crop garlic. The growth of the Chinese cabbage, disease occurrence, soil chemical properties and changes in microbial community structure were determined by using quantitative real-time polymerase chain reaction (PCR), soil microbial high-throughput sequencing and other methods. The results showed that the rotation of potato onion and wheat with Chinese cabbage could reduce the clubroot disease index of Chinese cabbage remarkably. Through Illumina Miseq sequencing, when three previous crops were harvested, the abundance and diversity of the bacteria increased obviously, while the fungi decreased. The relative abundance of the phylum Proteobacteria and Firmicutes was strikingly reduced, while that of Chloroflexi was significantly increased. These results show that three previous crops changed the structure of soil microorganisms, reduced the clubroot disease of Chinese cabbage, promoted growth, and suppressed disease. The ranked effect on promoting growth and inhibiting diseases was potato onion > wheat > soybean. [ABSTRACT FROM AUTHOR]

Clubroot resistance (CR) is an important trait in Chinese cabbage breeding worldwide. Although Crr1a, the gene responsible for clubroot-resistance, has been cloned and shown to encode the NLR protein, its allelic variation and molecular function remain unknown. Here, we investigated the sequence variation and function of three Crr1a alleles cloned from six CR F1 cultivars of Chinese cabbage. Gain-of-function analysis revealed that Crr1aKinami90_a isolated from the cv. ‘Kinami 90’ conferred clubroot resistance as observed for Crr1aG004 . Because two susceptible alleles commonly lacked 172 amino acids in the C-terminal region, we investigated clubroot resistance in transgenic Arabidopsis harboring the chimeric Crr1a, in which 172 amino acids of the functional alleles were fused to the susceptible alleles. The fusion of the C-terminal region to the susceptible alleles restored resistance, indicating that their susceptibility was caused by the lack of the C-terminus. We developed DNA markers to detect the two functional Crr1a alleles, and demonstrated that the functional Crr1a alleles were frequently found in European fodder turnips, whereas they were rarely introduced into Japanese CR cultivars of Chinese cabbage. These results would contribute to CR breeding via marker)assisted selection and help our understanding of the molecular mechanisms underlying clubroot resistance. [ABSTRACT FROM AUTHOR]

Plasmodiophora brassicae , an obligate biotrophic pathogen-causing clubroot disease, can seriously affect Brassica crops worldwide, especially Chinese cabbage. Understanding the transcriptome and metabolome profiling changes during the infection of P. brassicae will provide key insights in understanding the defense mechanism in Brassica crops. In this study, we estimated the phytohormones using targeted metabolome assays and transcriptomic changes using RNA sequencing (RNA-seq) in the roots of resistant (BrT24) and susceptible (Y510-9) plants at 0, 3, 9, and 20 days after inoculation (DAI) with P. brassicae. Differentially expressed genes (DEGs) in resistant vs. susceptible lines across different time points were identified. The weighted gene co-expression network analysis of the DEGs revealed six pathways including "Plant–pathogen interaction" and "Plant hormone signal transduction" and 15 hub genes including pathogenic type III effector avirulence factor gene (RIN4) and auxin-responsive protein (IAA16) to be involved in plants immune response. Inhibition of Indoleacetic acid, cytokinin, jasmonate acid, and salicylic acid contents and changes in related gene expression in R-line may play important roles in regulation of clubroot resistance (CR). Based on the combined metabolome profiling and hormone-related transcriptomic responses, we propose a general model of hormone-mediated defense mechanism. This study definitely enhances our current understanding and paves the way for improving CR in Brassica rapa. [ABSTRACT FROM AUTHOR]

Clubroot is an important disease infectible to cruciferous plants and a major threat to rapeseed production in Japan. However, no clubroot resistant rapeseed cultivars have been released. We surveyed pathotype variation of six isolates collected from rapeseed fields and found they were classified as pathotype groups 2 and 4 using Japanese F1 Chinese cabbage cultivars. We produced the resynthesized clubroot resistant Brassica napus harboring two resistant loci, Crr1 and Crr2, by interspecific crossing and developed resistant rapeseed lines for southern and northern regions by marker-assisted selection and backcrossing. We improved the DNA marker for erucic acid content to remove linkage drag between Crr1 and high erucic acid content and successfully selected lines with clubroot resistance and zero erucic acid for northern regions. A novel line, 'Tohoku No. 106', suitable for southern regions showed stable resistance against all six isolates and high performance in infested fields. We conclude that Crr1 and Crr2 are important genes for CR rapeseed breeding and marker-assisted selection is effective in improving clubroot resistance. [ABSTRACT FROM AUTHOR]

Clubroot, caused by the soil-borne protist Plasmodiophora brassicae , is one of the most destructive diseases of Chinese cabbage worldwide. However, the clubroot resistance mechanisms remain unclear. In this study, in both clubroot-resistant (DH40R) and clubroot-susceptible (DH199S) Chinese cabbage lines, the primary (root hair infection) and secondary (cortical infection) infection stages started 2 and 5 days after inoculation (dai), respectively. With the extension of the infection time, cortical infection was blocked and complete P. brassica resistance was observed in DH40R, while disease scales of 1, 2, and 3 were observed at 8, 13, and 22 dai in DH199S. Transcriptome analysis at 0, 2, 5, 8, 13, and 22 dai identified 5,750 relative DEGs (rDEGs) between DH40R and DH199S. The results indicated that genes associated with auxin, PR, disease resistance proteins, oxidative stress, and WRKY and MYB transcription factors were involved in clubroot resistance regulation. In addition, weighted gene coexpression network analysis (WGCNA) identified three of the modules whose functions were highly associated with clubroot-resistant, including ten hub genes related to clubroot resistance (ARF2 , EDR1 , LOX4 , NHL3 , NHL13 , NAC29 , two AOP1 , EARLI 1 , and POD56). These results provide valuable information for better understanding the molecular regulatory mechanism of Chinese cabbage clubroot resistance. [ABSTRACT FROM AUTHOR]

Clubroot, caused by the soil-borne protist Plasmodiophora brassicae, is one of the most destructive diseases of Chinese cabbage worldwide. However, the clubroot resistance mechanisms remain unclear. In this study, in both clubroot-resistant (DH40R) and clubroot-susceptible (DH199S) Chinese cabbage lines, the primary (root hair infection) and secondary (cortical infection) infection stages started 2 and 5 days after inoculation (dai), respectively. With the extension of the infection time, cortical infection was blocked and complete P. brassica resistance was observed in DH40R, while disease scales of 1, 2, and 3 were observed at 8, 13, and 22 dai in DH199S. Transcriptome analysis at 0, 2, 5, 8, 13, and 22 dai identified 5,750 relative DEGs (rDEGs) between DH40R and DH199S. The results indicated that genes associated with auxin, PR, disease resistance proteins, oxidative stress, and WRKY and MYB transcription factors were involved in clubroot resistance regulation. In addition, weighted gene coexpression network analysis (WGCNA) identified three of the modules whose functions were highly associated with clubroot-resistant, including ten hub genes related to clubroot resistance (ARF2, EDR1, LOX4, NHL3, NHL13, NAC29, two AOP1, EARLI 1, and POD56). These results provide valuable information for better understanding the molecular regulatory mechanism of Chinese cabbage clubroot resistance.

Clubroot caused by Plasmodiophora brassicae is one of the most destructive diseases in cruciferous crops. Streptomyces alfalfae XY25 T , a biological control agent, exhibited great ability to relieve clubroot disease, regulate rhizosphere bacterial and fungal communities in Chinese cabbage, and promote its growth in greenhouse. Therefore, field experiments were carried out to investigate the effects of S. alfalfae XY25 T on clubroot and rhizosphere microbial community in Chinese cabbage. Results showed that the control efficiency of clubroot by S. alfalfae XY25 T was 69.4%. Applying the agent can alleviate soil acidification; increase the contents of soil organic matter, available nitrogen, available phosphorus, and available potassium; and enhance activities of invertase, urease, catalase, and alkaline phosphatase. During Chinese cabbage growth, bacterial diversity decreased first and then increased, and fungal diversity decreased gradually after inoculation with S. alfalfae XY25 T . High-throughput sequencing analysis showed that the main bacterial phyla were Proteobacteria, Bacteroidetes, Acidobacteria, and Planctomycetes, and the major fungal phyla were Ascomycota and Basidiomycota in rhizosphere soil. The dominant bacterial genera were Flavobacterium , Candidatus , Pseudomonas , Stenotrophomonas , Sphingomonas , Flavisolibacter , and Gemmatimonbacteria with no significant difference in abundance, and the major fungal genera were Monographella , Aspergillus , Hypocreales , Chytridiaceae , Fusarium , Pleosporales , Agaricales , Mortierella , and Pleosporales. The significant differences were observed among Pleosporales , Basidiomycota , Colletotrichum , two strains attributed to Agaricales , and another two unidentified fungi by using S. alfalfae XY25 T . Moreover, quantitative real-time PCR results indicated that P. brassicae content was significantly decreased after the agent inoculation. In conclusion, S. alfalfae XY25 T can affect rhizosphere microbial communities; therefore, applying the agent is an effective approach to reduce the damage caused by clubroot. [ABSTRACT FROM AUTHOR]

Clubroot, caused by the obligate parasite Plasmodiophora brassicae , is one of the most important diseases of brassicas. The antagonistic bacterium Paenibacillus polymyxa ZF129 can suppress clubroot while its effectiveness is often unstable. To control clubroot more effectively, the macrobeads for controlled release of ZF129 were prepared using microencapsulation technology. Macrobeads with various ratios of chitosan (2 % w/w): carrageenan (0.3 % w/v) were prepared by an ionotropic gelation method and the bacteria ZF129 was loaded into macrobeads. The 1:1 chitosan: carrageenan showed the maximum swelling ratio (634 %), and the maximum survival rate (61.52 ± 1.12 %) after freeze-drying. Fourier transform infrared revealed the electrostatic interactions between chitosan and carrageenan. The macrobeads can efficiently release ZF129 strains into phosphate buffer solution and reach equilibrium in 48 h. The maximum number of bacteria cells to be released in the soil was observed after 25–30 days. The control efficacy of ZF129 macrobeads (chitosan: carrageenan, 1:1) and ZF129 culture against clubroot disease was 76.33 ± 3.65 % and 59.76 ± 4.43 % in greenhouse experiments, respectively and the control efficacy was calculated as 60.74 ± 5.00 % for ZF129 macrobeads and 40.94 ± 4.05 % for ZF129 culture under field experiments, respectively. The ZF129 macrobeads had significant growth-promoting effects on pak choi and Chinese cabbage. The encapsulation method described in this study is a prudent approach toward efficient biopesticides utilization with reduced environmental implications. • The 1:1 chitosan: carrageenan showed the maximum swelling ratio. • The 1:1 chitosan: carrageenan showed the maximum survival rate. • Bacteria cells can release into the soil from macrobeads in a slow manner. • Macrobeads significantly improve the control efficacy of free bacteria on clubroot. [ABSTRACT FROM AUTHOR]

Abstract Background Plasmodiophora brassicae is a soil-borne plant pathogen that causes clubroot disease, which results in crop yield loss in cultivated Brassica species. Here, we investigated whether a quantitative trait locus (QTL) in B. rapa might confer resistance to a Korean P. brassicae pathotype isolate, Seosan. We crossed resistant and susceptible parental lines and analyzed the segregation pattern in a F2 population of 348 lines. We identified and mapped a novel clubroot resistance QTL using the same mapping population that included susceptible Chinese cabbage and resistant turnip lines. Forty-five resistant and 45 susceptible F2 lines along with their parental lines were used for double digest restriction site-associated DNA sequencing (ddRAD-seq). High resolution melting (HRM)-based validation of SNP positions was conducted to confirm the novel locus. Results A 3:1 ratio was observed for resistant: susceptible genotypes, which is in accordance with Mendelian segregation. ddRAD-seq identified a new locus, CRs, on chromosome A08 that was different from the clubroot resistance (CR) locus, Crr1. HRM analysis validated SNP positions and constricted CRs region. Four out of seventeen single nucleotide polymorphisms (SNPs) positions were within a 0.8-Mb region that included three NBS-LRR candidate genes but not Crr1. Conclusion The newly identified CRs locus is a novel clubroot resistance locus, as the cultivar Akimeki bears the previously known Crr1 locus but remains susceptible to the Seosan isolate. These results could be exploited to develop molecular markers to detect Seosan-resistant genotypes and develop resistant Chinese cabbage cultivars.

Crop rotation can improve soil properties and is one of the important measures to prevent soil-borne diseases. This study aimed to evaluate the effects of different preceding crops on clubroot disease in Chinese cabbage and soil microorganisms, to provide a theoretical basis for the ecological control of clubroot scientifically. In this experiment, soybeans, potato onions, and wheat were used as the preceding crops and compared with the local preceding crop garlic. The growth of the Chinese cabbage, disease occurrence, soil chemical properties and changes in microbial community structure were determined by using quantitative real-time polymerase chain reaction (PCR), soil microbial high-throughput sequencing and other methods. The results showed that the rotation of potato onion and wheat with Chinese cabbage could reduce the clubroot disease index of Chinese cabbage remarkably. Through Illumina Miseq sequencing, when three previous crops were harvested, the abundance and diversity of the bacteria increased obviously, while the fungi decreased. The relative abundance of the phylum Proteobacteria and Firmicutes was strikingly reduced, while that of Chloroflexi was significantly increased. These results show that three previous crops changed the structure of soil microorganisms, reduced the clubroot disease of Chinese cabbage, promoted growth, and suppressed disease. The ranked effect on promoting growth and inhibiting diseases was potato onion > wheat > soybean.

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plasmodiophora brassicae , which is known for its broad genetic diversity for virulence, is the causal agent of clubroot disease of Brassica crops worldwide. Studies on pathotype characterization with four differential hosts according to Williams' classification system showed the predominance of pathotype 4 in China. However, the genetic variability within pathotype 4 complicates the breeding of durable clubroot-resistant (CR) cultivars. Herein, a Sinitic clubroot differential (SCD) set was developed using a set of eight differential inbred lines of Chinese cabbage with known or novel CR genes. The presence of immense diversity within pathotype 4 of Williams' system was verified, and 11 pathotypes were characterized using the developed SCD system. The scalability and practicability of the system was further confirmed with a subset of 95 field isolates from different Brassica crops and different regions of China and Korea. Sixteen pathotypes were detected from 132 field isolates, named Pb1 to Pb16, respectively. Among them, Pb1 and Pb4 were prevalent in diverse Brassica crops in the southern and northern regions of China. Pb12, Pb13, Pb14, and Pb16 showed area-specific distribution. The SCD set developed herein will provide important genetic resources for pathogenicity studies of P. brassicae and for CR breeding in Chinese cabbage and other Brassica crops. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research aimed to evaluate the effect of clubroot disease on the yield of two canola hybrids with different clubroot resistance levels under field conditions in Alberta. In Alberta, Canada, clubroot ( I Plasmodiophora brassicae i Woronin) is managed mainly by planting clubroot resistant (CR) canola ( I Brassica napus i L.) cultivars. Clubroot, caused by I Plasmodiophora brassicae i Woronin, is a soil-borne disease that has become a constraint to canola ( I Brassica napus i L.) production in Alberta, Canada. In the control treatments at all inoculum levels, the susceptible canola developed severe clubroot (92-100%) while the moderately resistant canola developed mild clubroot (9-13%). Several 4-year rotation sequences with resistant canola cultivars reduced the severity of clubroot compared with continuous canola, although a 4-year non-host or fallow sequence reduced clubroot incidence to zero. [Extracted from the article]

Highlights • A highly potent strain Bacillus subtilis XF-1 has strong inhibitory effects on the resting spores of P. brassicae. • The suppression effects on clubroot increased with increased seedling age. • We concluded that prevention and treatment at early stage is the best way to reduce the damage of clubroot disease. Abstract Clubroot caused by Plasmodiophora brassicae Woron is one of the most destructive diseases of Chinese cabbage (Brassica napus). A highly potent strain of Bacillus subtilis , XF-1, which was isolated from the rhizosphere of Chinese cabbages with severe clubroot in Guandu District of Kunming, Yunnan Province, China, had strong inhibitory effects on both the survival and germination of resting spores of P. brassicae. Several strategies were evaluated to efficiently manage clubroot in Chinese cabbage, and different mechanisms were investigated. The ability of Chinese cabbage root hairs to reduce infection by P. brassicae in the growth and efficiency of colonization of XF-1 on seedling roots was also studied. Responses to the suppression of clubroot increased with increased seedling age in pot and field conditions, and the rate of noninfectious root hair was enhanced by the inoculation of pathogens, suggesting that seedling age impacts the infection by P. brassicae. The application of B. subtilis XF-1 liquid culture for treatment during the developmental stages of infected Chinese cabbage seedlings gradually decreased the control effect. Moreover, soaking seeds with B. subtilis XF-1 culture reduced clubroot disease incidence rate and disease incidence by 40% and 69%, respectively. These results indicate that prevention and treatment by B. subtilis XF-1 at an early stage is the best way to reduce the damage caused by clubroot disease. [ABSTRACT FROM AUTHOR]

Straw amendment can improve soil properties and is an effective strategy to control soil-borne diseases. However, gramineous straw application to vegetable fields has rarely been studied. In this study, rice straw was added to the field of Chinese cabbage for one or two years (repeated), and Chinese cabbage plant growth, disease occurrence and changes in soil chemical properties were measured. In addition, the bacterial community composition of Chinese cabbage was analyzed using Illumina MiSeq sequencing. Results showed that rice straw application increased the content of available nutrients, pH and electrical conductivity, but decreased the diversity and richness of the bacterial community. The relative abundances of Acidobacteria and Chloroflexi were increased after repeated rice straw application, which were associated with the available potassium and pH in the soil. Network analysis revealed that rice straw amendment differentially affected the key bacterial genera. These results suggest that repeated application of rice straw changed the soil chemical properties and altered the bacterial community composition to suppress the clubroot disease incidence in Chinese cabbage.

Clubroot disease caused by Plasmodiophora brassicae is one of the most serious diseases in Brassica crops worldwide. In this study, the pathotypes of 12 Korean P. brassicae field isolates were determined using various Chinese cabbage including 22 commercial cultivars from Korea, China, and Japan, and 15 inbred lines. All P. brassicae isolates exhibited the typical clubroot disease on non-clubroot resistant cultivar, indicating that the isolates were highly pathogenic. According to the reactions on the Williams’ hosts, the 12 field isolates were initially classified into five races. However, when these isolates were inoculated onto clubroot-resistant (CR) cultivars of Chinese cabbage, several isolates led to different disease responses even though the isolates have been assigned to the same race by the Williams’ host responses. Based on the pathogenicity results, the 12 field isolates were reclassified into four different groups: pathotype 1 (GN1, GN2, GS, JS, and HS), 2 (DJ and KS), 3 (HN1, PC, and YC), and 4 (HN2 and SS). In addition, the CR cultivars from Korea, China, and Japan exhibited distinguishable disease responses to the P. brassicae isolates, suggesting that the 22 cultivars used in this study, including the non-CR cultivars, are classified into four different host groups based on their disease resistance. Combining these findings, the four differential hosts of Chinese cabbage and four pathotype groups of P. brassicae might provide an efficient screening system for resistant cultivars and a new foundation of breeding strategies for CR Chinese cabbage.

Auxins play a pivotal role in clubroot development caused by the obligate biotroph Plasmodiophora brassicae. In this study, we investigated the pattern of expression of 23 genes related to auxin biosynthesis, reception, and transport in Chinese cabbage (Brassica rapa) after inoculation with P. brassicae. The predicted proteins identified, based on the 23 selected auxin-related genes, were from protein kinase, receptor kinase, auxin responsive, auxin efflux carrier, transcriptional regulator, and the auxin-repressed protein family. These proteins differed in amino acids residue, molecular weights, isoelectric points, chromosomal location, and subcellular localization. Leaf and root tissues showed dynamic and organ-specific variation in expression of auxin-related genes. The BrGH3.3 gene, involved in auxin signaling, exhibited 84.4-fold increase in expression in root tissues compared to leaf tissues as an average of all samples. This gene accounted for 4.8-, 2.6-, and 5.1-fold higher expression at 3, 14, and 28 days post inoculation (dpi) in the inoculated root tissues compared to mock-treated roots. BrNIT1, an auxin signaling gene, and BrPIN1, an auxin transporter, were remarkably induced during both cortex infection at 14 dpi and gall formation at 28 dpi. BrDCK1, an auxin receptor, was upregulated during cortex infection at 14 dpi. The BrLAX1 gene, associated with root hair development, was induced at 1 dpi in infected roots, indicating its importance in primary infection. More interestingly, a significantly higher expression of BrARP1, an auxin-repressed gene, at both the primary and secondary phases of infection indicated a dynamic response of the host plant towards its resistance against P. brassicae. The results of this study improve our current understanding of the role of auxin-related genes in clubroot disease development.

The obligate biotroph Plasmodiophora brassicae causes clubroot disease in oilseeds and vegetables of the Brassicaceae family, and cytokinins play a vital role in clubroot formation. In this study, we examined the expression patterns of 17 cytokinin-related genes involved in the biosynthesis, signaling, and degradation in Chinese cabbage inoculated with the Korean pathotype group 4 isolate of P. brassicae, Seosan. This isolate produced the most severe clubroot symptoms in Chinese cabbage cultivar “Bullam-3-ho” compared to three other Korean geographical isolates investigated. BrIPT1, a cytokinin biosynthesis gene, was induced on Day 1 and Day 28 in infected root tissues and the upregulation of this biosynthetic gene coincided with the higher expression of the response regulators BrRR1, on both Days and BrRR6 on Day 1 and 3. BrRR3 and 4 genes were also induced during gall enlargement on Day 35 in leaf tissues. The BrRR4 gene, which positively interact with phytochrome B, was consistently induced in leaf tissues on Day 1, 3, and 14 in the inoculated plants. The cytokinin degrading gene BrCKX3-6 were induced on Day 14, before gall initiation. BrCKX2,3,6 were induced until Day 28 and their expression was downregulated on Day 35. This insight improves our current understanding of the role of cytokinin signaling genes in clubroot disease development.