Identification and biological characteristics of violet root rot pathogen of Pseudostellaria heterophylla in Fujian province / 中国中药杂志

Violet root rot is one of the main root diseases in the production process of Pseudostellaria heterophylla. To clarify the pathogenic species that cause the violet root rot of P. heterophylla in Fujian province, the roots and the sclerotia with violet root rot symptoms were collected from the main producing areas of P. heterophylla(Fujian province) from 2017 to 2021, and the pathogens were isolated by tissue separation method and identified by morphology and multi-gene phylogenetic analysis. Additionally, the biological characteristics of the pathogens were studied and the fungicides were determined. The results showed that 78 strains of violet root rot were isolated from the collected root samples, which belonged to one type after preliminary morphological identification. Two represen-tative strains were selected from the pathogens for multi-gene phylogenetic analysis, and they were clustered with Helicobasidium mompa together. The suitable culture conditions for the mycelium were OA medium, 25 ℃, pH 6, and ammonium oxalate as the nitrogen source. The lethal temperature of the mycelium was 50 ℃ for 10 minutes. Moreover, 99.1% propiconazole and 98.7% azoxystrobin had the optimal bacteriostatic effect, and the concentrations with the 50% bacteriostatic rate were 16.85 and 12.24 μg·mL~(-1), respectively. On the basis of the above results, the pathogen causing violet root rot of P. heterophylla in Fujian province was H. mompa. The medium type, growth temperature, pH value, nitrogen source, etc. had significant effect on the growth of mycelium.

Analysis of Fusarium oxysporum infection on changes of Astragalus metabolism by metabolomic approach / 药学学报

italic>Astragalus is a commonly used Chinese medicinal material in traditional Chinese medicine (TCM), and with the increase of planting area in recent years, the damage of Astragalus root rot has worsened year by year, which seriously affecting its quality and yield. Fusarium oxysporum is one of the main pathogens causing root rot in astragalus. In this study, UPLC-Q-TOF-MS based metabolomic approach combined with multivariate statistical analysis were used to analyze the metabolite changes of Astragalus in response to F. oxysporum infection. The results showed that 62 metabolites in the Astragalus had significant changes after inoculation of F. oxysporum. Polar metabolites included 40 flavonoids, 8 saponins, 2 nucleosides, 1 vitamin, 1 organic acid, 1 amino acid; while lipid metabolites included 3 fatty acids, 1 diradylglycerols, 2 lysophosphatidylcholine, 1 lysophosphatidylglycerol, 1 phosphatidylinositol, 1 sterol lipid. Among these differential metabolites, the relative content of flavonoids, vitamin B2, tryptophan and salicylic acid were increased, while the relative content of saponins were decreased. Correlation analysis showed that the flavonoids were positively correlated with each other, and positively correlated with most lipids, but negatively correlated with most saponins. In addition, studies have shown that F. oxysporum infection is not an influencing factor for the generation of malonyl substitution of flavonoid. This study elucidates the effect of F. oxysporum infection on Astragalus from the perspective of plant metabolism, which provides a basis for exploring the interaction mechanism between the Astragalus and F. oxysporum and further promoting molecular breeding.

Advances in research and application of Trichoderma for inducing resistance against root rot diseases in root and rhizome of Chinese medicinal materials / 中国中药杂志

Root rot is a microbial disease that is difficult to control and can result in serious losses in the planting of most Chinese medicinal materials. As high as 87.6% of roots or rhizomes of Chinese medicinal materials are susceptible to root rot, which seriously affects the cultivation development of Chinese medicinal materials. Trichoderma fungi, possessing biological control functions, can induce plants to improve their resistance to microbial diseases, promote plant growth, and effectively reduce the losses caused by various microbial diseases on cultivation. At present, Trichoderma is rarely used in the cultivation of Chinese medicinal materials, so it has great application potential for the prevention and control of root rot diseases in farmed Chinese medicinal materials. Based on the above situation, after comparison and discussion, it is believed that compared with chemical control and physical control, biological control of root rot diseases of Chinese medicinal materials is more efficient and meets the development needs of Chinese medicinal materials ecological planting in China. This paper reviewed the progress in the research and application of Trichoderma in the control of root rot diseases in the root and rhizome of farmed Chinese medicinal materials in the past 10 years and found that most of the current research on the biological control of root rot diseases in Chinese medicinal materials was mostly limited to the verification of the inhibitory effect of Trichoderma strains on the growth of the pathogenic microbes. Studies on the induction effect of Trichoderma on Chinese medicinal materials are not in depth. Studies on the responding mechanisms of most Chinese medicinal materials to Trichoderma are highly absent. Moreover, there are few reports on field experiments, which indicates that there is a long way to go before Trichoderma is widely applied in the farming practice of Chinese medicinal materials. To sum up, this paper aimed to link the present and the future and advocated further relevant research and more experiments on the application of Trichoderma in the farming of Chinese medicinal materials.

Development and Evaluation of Biocontrol Agents Against Panax ginseng Root Rot / 中国实验方剂学杂志

ObjectiveTo develop safe and effective microbial agents against Panax ginseng root rot. MethodP. notoginseng endophytes were screened in plate confrontation tests， followed by morphological and molecular biological identification of antagonistic strains， optimization of strain fermentation conditions in a single factor test， and determination of optimal carriers and auxiliary agents of the microbial agent and their ratio using response surface methodology for formulating the production process. The prevention and control effects of the microbial agent were verified in the confrontation and pot culture experiments. ResultThe plate confrontation test yielded a strain named Fusarium pseudoanthophilum with significant resistance to root rot， and its antibacterial rate was 53.33%. According to the single factor test， the fermentation conditions of F. pseudoanthophilum were determined to be fermentation time 60 h， fermentation temperature 26 ℃， speed 120 r·min-1， and pH 6.5. The response surface optimization results showed that the number of viable bacteria reached the maximum （5.23×109 cfu·g-1） when the peat was 60.00 g， sodium carboxymethylcellulose 3.50 g， and sodium alginate 4.76 g. The influences of carriers and auxiliary agents on the number of viable bacteria were sorted by degree in a descending order as follows： peat>sodium carboxymethylcellulose >sodium alginate. The confrontation test results showed that when the microbial agent concentration was greater than 1.00 g·L-1， it had a significant inhibitory effect on the root rot pathogen F. oxysporum and the inhibitory rate was more than 42.3%. As demonstrated by the pot culture experiment， the inoculation of biocontrol agent for 28 d significantly reduced the incidence （66.99%） of root rot in P. ginseng seedlings and disease index （61.69%） and increased their leaf length （33.04%） and fresh weight （34.48%）. ConclusionF. pseudoanthophilum inoculant is efficient in preventing and controlling the root rot， making it worthy of further development and utilization.

Effectiveness of indigenous fluorescent pseudomonads in suppressing Rhizoctonia solani root rot disease and promoting plant growth in chilli seedlings

Aims@#This study aimed to isolate and evaluate the indigenous fluorescent Pseudomonas spp. with bio-control potential against Rhizoctonia solani and promoting growth in chilli seedlings. @*Methodology@#A total of 120 fluorescent bacterial were isolated from the healthy chilli rhizosphere soil from the seven major chilli cultivation localities in Terengganu, Malaysia. Only 115 Gram negative fluorescent isolates were further invitro screened for antagonistic activities against R. solani and plant growth-promoting properties. The 50 most effective fluorescent Pseudomonads antagonist against R. solani with minimum percentage inhibition of radial growth (PIRG) of 65% were selected. Hierarchical cluster analysis was further conducted with two dendrograms derived from SPSS Statistic 20 to facilitate the comparison between these 50 isolates for antagonistic and growth-promoting properties. A total of 40 fluorescent isolates within the most potential cluster were further selected and identified using 16S rRNA sequencing. Thirty four fluorescent isolates were identified as Pseudomonas spp. and six isolates as Burkholderia spp. The top 13 ranked fluorescent Pseudomonas spp. from the scoring index were evaluated for seed germination and vigor index in chilli seedlings. There was no significant difference in germination rate between fluorescent Pseudomonas inoculated with control. However, vigor index of chilli seeds pre-inoculated with fluorescent P. putida (B5C1), P. aeruginosa (B3C56) and P. putida (B5C7) were significantly increased with 4684.9, 4657.3 and 4401.0 over control (P ≤ 0.05).@*Conclusion, significance and impact of study@#These selected fluorescent isolates: P. putida (B5C1), P. aeruginosa (B3C56) and P. putida (B5C7) have the potential to be developed as biofungicide against R. solani and as growthpromoter in chilli production system.

Isolation and identification of a new phytopathogen causing root rot of Rehmannia glutinosa / 中国中药杂志

Root rot was occurred widely in the production area of Rehmannia glutinosa, and which result in serious influence on the yield and quality of R. glutinosa. In the present work, a new phytopathogen was isolated from roots with root rot symptom in the production area of R. glutinosa. The colony of the pathogen growing on PDA medium was gray-black, the structure of hyphae was compact, the aerial hyphae was less developed, and the back of the colony was black. The hyphae of the pathogen were uneven in size, about 2 to 3 μm in diameter and twined with each other, the conidia of the pathogen were small, nearly round and about 1 μm in diameter. The healthy roots of R. glutinosa were inoculated with the pathogen in vitro, black-brown rot was observed at the inoculate sites after a few days' incubation. The rhizosphere soil of healthy R. glutinosa seedlings were inoculated in vivo, the leaves were wilted and the roots were black-brown rotted after several days' normal culture, the symptoms were consistent with those observed in the field. The genomic DNA of the pathogen was amplified by fungus rDNA-ITS universal primer ITS1/ITS4 and homologous analyzed, the pathogen was in a branch with Heterophoma sp., Phoma sp., P. novae-verbascicola and P. herbarum with the nuclear acid homology of 99.21% to 99.43%. The pathogen shown 97.00% to 98.02% nuclear acid homology with H. verbascicola, H. novae-verbascicola, H. poolensis, P. herbarum, H. sylvatica, H. verbascicola and H. verbasci-densiflori when amplified by the tub2 gene special primer Btub2 fd/Btub4 rd, and H. novae-verbascicola was the highest. The pathogen was in a branch with H. novae-verbascicola when amplified by the lsu gene special primer LR0 R/LR7. Based on the morphological characteristics, nucleotide sequence analysis and Koch's test results, the isolated pathogen causing root rot of R. glutinosa was identified as H. novae-verbascicola. This study is of great significance for the further theoretical research on root rot of R. glutinosa and root rot control in field.

Real-time PCR detection method for Fusarium solani, pathogen of Panax notoginseng root rot / 中草药

Objective: In order to establish an accurate and rapid real-time fluorescence quantitative PCR method for the detection of Fusarium solani, the pathogenic fungus of Panax notoginseng root rot. Methods: Based on aminoadipate reductase Lys2 gene of F. solani, specific primers Fs-QF and Fs-QR were designed. The recombinant plasmid standard was prepared and the SYBR Green I fluorescence real-time quantitative PCR method and real-time fluorescent 1oop-mediated isothermal amplication (LAMP) system for detecting F. solani was established. Fifteen samples including P. notoginseng plants with typical symptoms of root rot and black spot as well as soil of P. notoginseng planting area were collected. The total DNA of these samples were extracted as templates, and then detected by the real-time fluorescence quantitative PCR method and 1oop-mediated isothermal amplification established in this study. Results: The real-time fluorescent quantitative PCR method and 1oop-mediated isothermal amplification technique established in this study had high specificity. P. notoginseng plants infected with F. solani can be detected quickly. In addition, the method has high sensitivity and the concentration of detection template can be as low as 0.2 pg/μL. Conclusion: The method established in this study can be used to reveal the dynamic changes of F. solani concentration in the complex P. notoginseng planting soil and diseased plants. Furthermore, it can provide technical supports for the soil treatment, early diagnosis and dynamic monitoring of root rot, and rapid molecular detection of P. notoginseng seeds and seedlings.

Effects of planting period on growth, yield and medicinal quality of Chrysanthemum morifolium / 中国中药杂志

In this paper, Chrysanthemum morifolium was used as the experimental object, eight different planting periods were set up in field plot experiment from April to August, which were 04-15, 05-19, 05-30, 06-09, 06-19, 07-20, 07-31, 08-15. The effects of different treatments on the occurrence of root rot, agronnmic traits, mineral element absorption and content of effective components of Ch. morifolium in Macheng country of Hubei province were studied. The results showed that delaying the planting time could effectively reduce the diseases occurrence of root rot of Ch. morifolium. With the advance of transplanting period, the plant height, the weight of one hundred flowers and the number of flowers of Ch. morifolium showed a trend of gradual decrease, while the number of primary branches and the thickness of main stem and the primary branch increased first and then decreased. The yield of Ch. morifolium per plant and per mu increased with the advance of the planting period, and the yield per mu increased during the planting period on June 19, which was 91.96% higher than that on April 15. And with the delay of the planting period,the absorption and accumulation of potassium(K) elements was promotes. The content of active ingredients such as chlorogenic acid, rutin, luteolin, and 3,5-O dicoffeoacy lquinic acid in the Ch. morifolium increased significantly and then gradually decreased with the delay of the planting period, which indicates that late planting can significantly improve the quality of Ch. morifolium. Considering factors such as the occurrence of root rot disease, yield and active ingredient content, combined with climatic conditions in the Dabie Mountains in eastern Hubei, the optimum planting period of Ch. morifolium was determined from mid-late June to early July.

Identification of Coptis chinensis root rot disease pathogenic Fusarium spp. fungi / 中国中药杂志

Root rot disease is vital disease of Coptis chinensis, it has bursted in most producing area in recent years, and has caused severe damage. To identify the pathogenic fungi, Fusarium spp. fungi were isolated from rot root, of which the pathogenic fungi were screened with inoculation on C. chinensis root and plant, and identified with molecular and morphological method. The 20 Fusarium spp. fungi were obtained, of which 5 displayed high pathogenicity. It was deduced that F. oxysporum, F. solani and F. tricinctum were the pathogen, possibly pioneer pathogen of C. chinensis root rot disease. Among which F. oxysporum was dominant and deserved to pay more attention. High temperature and high humidity can increase pathogenicity of Fusarium spp. So the global climate warming may lead to temperature rising of C. chinensis producing area and favor the pathogen fungi, which may be one of the main factors leading to bursting of C. chinensis root rot disease. To control the root rot, beside developing and using pesticide, producing base should be moved to a high altitude area.

Fungitoxic Potentials of Extracts of Plant Origin against Fugal Root Rot of Cassava (Manihot esculenta Crantz) in Storage

Investigations were carried out on the use of the water and ethanolic extracts of Piper guineense, Ocimum graticimum, Casia alata, and Tagetes erecta in the management of postharvest deterioration of cassava root caused by Aspergillus flavus and Rhizopus stolonifer. Water and ethanolic extracts of the plant materials had significant differences (p≤0.5) in their rates of fungitoxicity on the pathogenic organisms. Water and ethanol extracts of C. alata and T. erecta respectively at 50% concentration gave the same highest radial growth inhibition of 80.20% on A. flavus in vitro followed by ethanol extracts of C. alata, O. graticimum, and P. guineense. The ethanolic extract of T. erecta at 50% concentration gave the highest inhibitory effect of 53.50% on R. stolonifer followed by ethanol extracts of C. alata, O. graticimum, and P. guineense whereas the least growth inhibition of 0.17% was recorded by aqueous extract of P. guineense on R. stolonifer. In vivo test of the plant extracts applied before and after inoculation with spore suspension (1x105 spores/ml of distilled water) of test fungi showed significant reduction in root rot incidence and severity. The lowest incidence and severity of cassava root rot of 16.5% and 1.45 respectively were recorded with T. erecta ethanol extracts applied before inoculation of A. flavus indicating that the extracts of the plant materials could be better used as protectant than eradicant in the control of post harvest fungal deterioration of cassava root. R. stolonifer showed stronger resistance to the extracts of the plant materials than A. flavus during pathogenesis in vivo.

Screening and identification of antagonistic Bacillus against Astragalus membranaceus root rot and its effect on microorganism community in root zone soil / 中国中药杂志

The Astragalus membranaceus root rot disease,a soil-borne disease,has become increasingly severe in Shanxi province.This study was aimed at getting antagonistic Bacillus with excellent bio-control effects,and determining its effects on bacterial communities in root zone soil. With Fusarium solani and F. acuminatum as the target,antagonistic Bacillus was selected through such tests as living body dual culture,antifungal effect of bacteria-free filtrate,mycelia growth inhibition in vitro and control effect in detached roots,and identified with morphology,physio-biochemical characteristics and 16 S r DNA sequence analysis. The results showed that the Bacillus strain SXKF16-1 had obvious antifungal effect. The diameter of inhibition zone of its bacteria-free filtrate to F. solani and F. acuminatum was( 25. 90±1. 18) mm and( 25. 86±1. 85) mm respectively,and showed a lasting inhibition effect to mycelia growth. The disease index of the protective treatment and that of the cure treatment in detached roots test to F. solani and F. acuminatum were( 37. 50±8. 58),( 41. 67±4. 90) and( 25. 00±8. 33),( 38. 89±9. 62) respectively,both being significantly different( P<0. 05) from that of the control. The strain SXKF16-1 was identified as Bacillus atrophaeus. The B. atrophaeus SXKF16-1 showed significantly inhibition effect to pathogen causing root rot and could increase the bacterial diversity in root zone soil. It has potential to be developed as a special biocontrol agent.

Diversity of culturable fungi isolated from Coptis chinensis rot root in Shizhu city of Chongqing / 中国中药杂志

Root rot disease restricts the Coptis chinensis industry in Shizhu of Sichuan province. To disclose fungi composition and pathogen in rot root,so as to prevent and treat the root rot disease,the C. chinensis rot root of 5 years from 4 areas in Shizhu were collected in 3 seasons respectively. The fungi were isolated and molecularly and morphological identified,followed with population statistics. 437 fungi were isolated,belonging to 5 subphylum,11 classes,16 orders,22 families and 28 genus respectively. There are great difference among the fungi compositions of different area,year and sampling season,while there was no obvious variation rule. Ilyonectria sp.,Pythium sp.,Phoma sp,Trichoderma sp.are dominant genus,while Pythium sp.,Ilyonectria sp.,Phoma sp.,Fusarium sp. may contain root rot pathogen. Antagonistic bacteria may be screened from the strains of Trichoderma sp. isolated.

Illumina high-throughput sequencing reveals fungal community composition and diversity in root rot of Coptis chinensis in rhizosphere soil / 中草药

Objective To reveal fungal community composition and diversity in health and root rot of Coptis chinensis in rhizosphere soil. Methods High-throughput sequencing technology was used to characterize the fungal community composition, richness, and diversity of health and root rot Coptis chinensis in rhizosphere soil in Shizhu County of Chongqing Province. Spearman analysis was used to evaluate the correlation between soil physicochemical parameters and the first 35 most abundant fungal genera. Results More than 106 267 effective tags were obtained, and the community was composed of six phyla (Ascomycota, Zygomycota, Basidiomycota, Glomeromycota, Chytridiomycota, and Neocallimastigomycota). The fungal community diversity showed no significant difference in healthy and root rot samples. The relative abundance of Ascomycota, Basidiomycota and Chytridiomycota in root rot soil was significantly higher than that in healthy soil. Moreover, the relative abundance of Zygomycota, Glomeromycota, and Neocallimastigomycota in root rot soil was significantly lower than in healthy soil. The relative abundance of Fusarium was significantly higher in root rot samples than in healthy samples. Spearman analysis showed that the relative abundance of Fusarium was significantly positively correlated with pH and available phosphorus, but negatively correlated with alkali-hydrolyzable nitrogen. Conclusion Changes in soil physicochemical characteristics were related to the changes in soil fungal diversity.

Research on relationship between occurrence of root rot and changes of fungal communities in rhizosphere of Panax quinquefolius / 中国中药杂志

The root rot disease is a common disease during the cultivation of Panax quinquefolius. In order to provide some clues for solving the root rot disease of P. quinquefolius, the relationship between rhizosphere soil fungal communities and root rot of P. quinquefolius was investigated in this study. The diversities and the changes of fungal communities structure in blank control group (group C), rhizosphere soil of healthy P. quinquefolius (group N) and occurrence of root rot in rhizosphere soil of P. quinquefolius (group R)were analyzed byusing the Illumina MiSeq high-throughput sequencing technology. A total of 505 968 high-quality sequences were obtained through high-throughput sequencing and the rare faction curves analysis showed that the sequencing depth was sufficient and the sampling was reasonable. The fungal communities structure of rhizosphere soil samples mainly belonged to 9 phylums including Ascomycota(54.9%), Basidiomycota(5.6%), etc., and the dominant specie was Ascomycota of the total fungal identified, respectively. The 115 genera of fungi were tested, including Monographella (3.9%), Archaeorhizomyces (3.9%), Mortierella, etc., and the dominant specie was Monographella. At the genus level, the abundance of Monographella and Mortierella in group R increased significantly compared with the abundance in groups C and N. Alpha diversity index of species showed that the diversity index of fungal communities reduced and the numbers of fungi reduced in group N and R, compared with group C, and reaching the minimum in group R. Beta diversity index of species showed that there was a significant difference in the fungal communities structure in each sample. In addition, the heat map analysis revealed that the dominant fungal genera were significantly different among the each sample. The proportion of Monographella and Mortierella in group R was significantly higher than that in group C and N, while the proportion of Trichoderma,Penicillium and Cadophora in group R was extremely low. The proportion of Phoma and Gibberella in group R increased significantly compared with group C. This study clarified the decline of diversity index and the imbalance of community structure in fungi may lead to the occurrence of root rot in P. quinquefolius by analysis of fungal diversity and community composition in the rhizosphere soil of P. quinquefolius in this study, which provided a theoretical basis for the prevention and treatment of occurrence of root rot in P. quinquefolius.

Characterization and pathogenicity of Rhizoctonia SPP. isolated from vegetable crops grown in greenhouses in Samsun province, Turkey / Caracterização e patogenicidade de Rhizoctonia SPP. isolada a partir de culturas vegetais crescidas em estufas na província de Samsun, Turquia

A total of one hundred and five isolates of Rhizoctonia belonging to 7 anastomosis groups (AGs) were obtained from the diseased roots and rhizosphere soils of bean, cucumber, eggplant, pepper and tomato plants grown in greenhouses in Samsun province (Black Sea region, Turkey) during the period 2011­2012. The isolates of Rhizoctonia spp. were examined for their cultural characteristics, anastomosis groups and pathogenicity. Of these, 83.8% were multinucleate Rhizoctonia solani (AG-2, AG-4, AG-5 and AG-6) and 16.2% were binucleate Rhizoctonia (AG-A, AG-E and AG-F). Sixty five of the isolates belonged to AG-4 which was the most frequent group (61.9%) in all greenhouses surveyed. Numbers of the isolates belonging to AG-2 (7.6%), AG-5 (6.7%) and AG-6 (7.6%) were 8, 7 and 8, respectively. Seventeen isolates recovered from greenhouses surveyed were identified as binucleate Rhizoctonia AG-A (1.9%), AG-E (6.7%) and AG-F (7.6%). All isolates of Rhizoctonia spp. tested for growth rates grew at temperatures of 10, 15, 20, 25 and 30°C, whereas they were completely inhibited at 5°C. The results of pathogenicity tests showed that the differences in virulence among isolates of Rhizoctonia spp. were statistically significant (P < 0.001). The tests on bean seedlings showed that the highest disease severity was caused by AG-4 isolates. The disease severity index (DSI) of the R. solani AG-4 isolates ranged from 3.2 to 3.8. In addition, the isolates of three AGs belonging to binucleate Rhizoctonia spp. were generally found to be moderately virulent (DSI 2.0­2.4).

Um total de cento e cinco isolados de Rhizoctonia pertencentes a 7 grupos de anastomose (AGs) foram obtidos a partir de raízes doentes e solos rizosféricos de plantas de feijão, pepino, berinjela, pimenta e tomate cultivados em estufas na província de Samsun (região do Mar Negro, Turquia) durante o período 2011-2012. Os isolados de Rhizoctonia spp. foram examinados por suas características culturais, grupos de anastomose e patogenicidade. Destes, 83,8% eram Rhizoctonia solani multinucleadas (AG-2, AG-4, AG-5 and AG-6) e 16,2% era Rhizoctonia binucleadas (AGA, AG-E and AG-F). Sessenta e cinco dos isolados pertenciam ao AG-4, que foi o grupo mais freqüente (61,9%) em todas as estufas pesquisadas. O número de isolados pertencentes a AG-2 (7,6%), AG-5 (6,7%) e AG-6 (7,6%) foi de 8, 7 e 8, respectivamente. Dezessete isolados recuperados de estufas pesquisadas foram identificados como Rhizoctonia binucleada AG-A (1,9%), AG-E (6,7%) e AG-F (7,6%). Todos os isolados de Rhizoctonia spp. testados para taxas de crescimento cresceram a temperaturas de 10, 15, 20, 25 e 30ºC, enquanto que foram completamente inibidos a 5ºC. Os resultados dos testes de patogenicidade mostraram que as diferenças de virulência entre os isolados de Rhizoctonia spp. foram estatisticamente significativas (P <0,001). Os testes em mudas de feijão mostraram que a maior severidade da doença foi causada por isolados AG-4. O índice de gravidade da doença (do inglês, disease severity index - DSI) dos isolados de R. solani AG-4 variou de 3,2 a 3,8. Além disso, os isolados de três AGs pertencentes à Rhizoctonia spp. binucleadas foram geralmente encontrados como moderadamente virulentos (DSI 2,0-2,4).

Molecular cloning, bacterial expression analysis and functional characterization of pathogenesis-related PR10-2 gene in Panax notoginseng / 中国中药杂志

Base on the transcriptome analysis and RT-PCR techniques,a pathogenesis-related protein 10 gene was isolated from Panax notoginseng root and named as PnPR10-2. Bioinformatics and phylogenetic trees analysis revealed that open reading frame (ORF) of PnPR10-2 was 465 bp in length,encoding 154 amino acids,containing one typical conserved domain of pathogenesis related protein Bet v I family, and showed high similarity with that from P. ginseng. The recombinant expressed plasmid pET32a(+)-PnPR10-2 was expressed in Escherichia coli BL21. The expression conditions were optimized and it could be expressed well in soluble and inclusion body protein. Purified PnPR10-2 recombinant protein from the supernatant of cells was used to analysis the pathogen resistance activity by paper method. The purified recombinant protein could inhibit typical root rot disease pathogen (Fusarium solani and Cylindrocarpon destructans）growth evidently, we conjecture that PnPR10-2 may participated in defense response of P. notoginseng resistance to root rot disease pathogen.

Antagonistic Evaluation of Chromobacterium sp. JH7 for Biological Control of Ginseng Root Rot Caused by Cylindrocarpon destructans

Cylindrocarpon destructans is an ascomycete soil-borne pathogen that causes ginseng root rot. To identify effective biocontrol agents, we isolated several bacteria from ginseng cultivation soil and evaluated their antifungal activity. Among the isolated bacteria, one isolate (named JH7) was selected for its high antibiotic activity and was further examined for antagonism against fungal pathogens. Strain JH7 was identified as a Chromobacterium sp. using phylogenetic analysis based on 16S rRNA gene sequences. This strain was shown to produce antimicrobial molecules, including chitinases and proteases, but not cellulases. Additionally, the ability of JH7 to produce siderophore and solubilize insoluble phosphate supports its antagonistic and beneficial traits for plant growth. The JH7 strain suppressed the conidiation, conidial germination, and chlamydospore formation of C. destructans. Furthermore, the JH7 strain inhibited other plant pathogenic fungi. Thus, it provides a basis for developing a biocontrol agent for ginseng cultivation.

Research on bacteria microecology in root rot rhizosphere soil of Coptis chinensis produced in Shizhu city / 中国中药杂志

Illumina Hiseq 2500 high-throughput sequencing platform was used to study the bacteria richness and diversity, the soil enzyme activities, nutrients in unplanted soil, root-rot and healthy rhizophere soil of Coptis chinensis for deeply discussing the mechanism of the root-rot of C. chinensis. The high-throughput sequencing result showed that the artificial cultivation effected the bacteria community richness and diversity. The bacteria community richness in healthy and diseased rhizosphere soil showed significant lower than that of in unplanted soil (P<0.05) and declined bacteria diversity. The bacteria community richness in root-rot rhizosphere soil increased significantly than that of health and unplanted soil and the diversity was lower significant than that of unplanted soil (P<0.05). The results of soil nutrients and enzyme activities detected that the pH value, available phosphorus and urease activity decreased and the sucrase activity increased significantly (P<0.05). The content of organic carbon and alkaline hydrolysis nitrogen the catalase and urease activity in root rot soil samples was significantly lower than that of healthy soil samples (P<0.05). However, the contents of available phosphorus and available potassium were significantly in root-rot sample higher than that of healthy soil samples (P<0.05). Comprehensive analysis showed that the artificial cultivation declined the bacteria community richness and diversity. The bacteria community richness decreased significantly and the decreased diversity may be the cause of the root-rot. Meanwhile, the decrease of carbon and the catalase activity may be another cause of the root-rot in C. chinensis produced in Shizhu city, Chongqing province.

DNA marker-assisted selection of medicinal plants (Ⅲ)Evaluation of disease resistance of "Miaoxiang Kangqi 1" --a new cultivar of Panax notoginseng / 中国中药杂志

DNA marked-assisted selection of medicinal plants accelerated the breeding and promotion of new cultivars, and guaranteed the healthy development of Chinese medicinal materials industry. The first disease-resistant cultivar of notoginseng, namely "Miaoxiang Kangqi 1", served as the object of study. We evaluated the Kangqi's resistance of seeds, seedlings and root against the pathological bacteria (Fusarum oxysporum) of root rot. Compared to the traditional cultivars, the disease index of notoginseng seeds declined by 52.0% after inoculation for seven days; the death rate of seedlings and disease index of root respectively decreased by 72.1% and 62.4% after inoculation for 25 days. Additionally, the growth inhibition ratio of notoginseng seeds and seedlings declined after inoculation. The seeds, seedlings and roots of "Miaoxiang Kangqi 1" showed significantly resistant to root rot. The evaluation of disease-resistance of Kangqi provided the basis for the popularization of new cultivar and guaranteed the favoring conduct of notoginseng pollution-free cultivation.

First Report of Root Rot Caused by Plectosphaerella cucumerina on Cabbage in China

Severe root rot was observed in fields of cabbages (Brassica oleracea L.) in 2015 in China. Cardinal symptoms of this disease included root rot and wilting leaves. A fungus was isolated from diseased tissues consistently. Based on the morphological features and molecular analysis of the ITS-5.8S rDNA and D1/D2 domain of the 28S rRNA gene, it was identified as Plectosphaerella cucumerina. This is the first report of P. cucumerina causing cabbage root rot in China and the world.