Morpho-molecular Characterization of Carrot Soft Rot Incitant, Pectobacterium carotovorum subsp carotovoroum

Carrot is an important root vegetable which plays an important role in human health. Globally, Post harvest diseases are the major constraint in carrot production, especially soft rot which resulting in severe yield loss. Early diagnosis of these post-harvest diseases paves a way for reducing the economic losses. Carrot samples showing typical rotting symptoms were collected from markets of four different districts of Tamil Nadu and the pathogen involved were isolated. Severe carrot soft rot incidence (66.74%) was observed in samples collected from Ooty area of The Nilgiris district and the least disease incidence of (16.21%) was recorded in Perundurai of Erode district. Pathogenicity of soft rot pathogen were conducted and the virulent isolates were identified based on Percent Disease Index (PDI) showing >50% rotting falls under disease grade 9 using disease grade scale (0 to 9). The bacterial isolates (KPB-7 and OCB-5) causing soft rot were characterized using various biochemical assays where in they showed positive response for methyl red, H2S gas production, KOH and catalase tests besides showing negative response for gram’s reaction. Furthermore, molecular characterization of 16s rRNA region revealed the soft rot isolate (KPB-7) as Pectobacterium carotovorum subsp carotovorum (with an accession number OR251119).

Identification, biological characteristics, and control of pathogen causing Pinellia ternata soft rot in Hubei province / 中国中药杂志

This study was designed to identify the pathogen causing soft rot of Pinellia ternata in Qianjiang of Hubei province and screen out the effective bactericides, so as to provide a theoretical basis for the control of soft rot of P. ternata. In this study, the pathogen was identified based on molecular biology and physiological biochemistry, followed by the detection of pathogenicity and pathogenicity spectrum via plant tissue inoculation in vitro and the indoor toxicity determination using the inhibition zone method to screen out bactericide with good antibacterial effects. The control effect of the bactericide against P. ternata soft rot was verified by the leave and tuber inoculation in vitro. The phylogenetic tree was constructed based on the 16 S rDNA, dnaX gene, and recA gene sequences, respectively, and the result showed that the pathogen belonged to the same branch as the type strain Dickeya fangzhongdai JS5. The physiological and biochemical tests showed that the pathogen was identical to D. fangzhongdai, which proved that the pathogen was D. fangzhongdai. The pathogenicity test indicated that the pathogen could obviously infect leaves at 24 h and tubers in 3 d. As revealed by the indoor toxicity test, 0.3% tetramycin, 5% allicin, and 80% ethylicin had good antibacterial activities, with EC_(50) values all less than 50 mg·L~(-1). Tests in tissues in vitro showed that 5% allicin exhibited the best control effect, followed by 0.3% tetramycin and 10% zhongshengmycin oligosaccharide, and their preventive effects were better than curative effects. Therefore, 5% allicin can be used as the preferred agent for the control of P. ternata soft rot, and 0.3% tetramycin and 10% zhongshengmycin oligosaccharide as the alternatives. This study has provided a certain theoretical basis for the control of P. ternata soft rot.

Biocontrol capability of bacteriophages against soft rot disease caused by Dickeya chrysanthemi

Aims@#This study aims to evaluate the effectiveness of bacteriophages isolated from Klang and Penang, Malaysia against Dickeya chrysanthemi that causes soft rot disease.@*Methodology and results@#Basic characterization such as dextrose test, citrate test, lactose fermentation test and ornithine test were carried out on D. chrysanthemi. Activity of bacteriophages against D. chrysanthemi was evaluated using spot test. Double agar overlay assay was performed to purify and enumerate the quantify of bacteriophages.Bacteriophages were also checked for its effectiveness in controlling soft rot on post-harvested vegetables: potato (Solanum tuberosum), cucumber (Cucumis sativus) and apple (Malus domestica). Results showed that D. chrysanthemiable to utilize citrate and dextrose as the source of energy, which indicated that D. chrysanthemi inclined to choose fruits and vegetables containing citrate and dextrose as the target of attack. Clear zone observed on the bacterial lawn (spot test) indicated the ability of the bacteriophages to infect and lyse D. chrysanthemi. All the bacteriophages studied herein reached the highest concentration on day 3 and were monovalent.@*Conclusion, significance and impact of study@#All the isolated bacteriophages were able to restrain the spreading of soft rot caused by D. chrysanthemi either work alone or as cocktail. This study provides information for the formulation development of bacteriophage against soft rot disease cause by D. chrysanthemi. Furthermore, this study reveals the potential of locally isolated bacteriophages against the D. chrysanthemi and paving the application of phage treatment on agriculture products that are not limited to potatoes, cucumber and apple.

Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages

One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

olecular Analysis of Genetic Diversity of Pectobacterium carotovorum Subsp Carotovorum Isolated in Morocco by PCR Amplification of the 16S-23S Intergenic Spacer Region.

Aims: Pectobacterium carotovorum is a ubiquitous bacterium that causes soft rot in different crop plants throughout the world. In Morocco, approximately 95% of the Strains isolates from potato plants with tuber soft rot are P. carotovorum. In this study, we test whether PCR ribotyping can be used to distinguish strains of Pectobacterium carotovorum isolated from soft rot potato and to differentiate among strains from different geographic regions. Place and Duration of Study: Laboratory of Virology, Microbiology and Quality / Ecotoxicology and Biodiversity, department Biology, Faculty of Sciences and Techniques, University Hassan-II Mohammedia Casablanca. Methodology: Eighty-three pectolytic enterobacteria were collected from potatoes rotten in Morocco, the strains were isolated in the Cristal Violet Pectate (CVP) medium and were purified in LPGA agar (yeast extract, peptone, glucose and agar). After purification, strains were identified by physiological and biochemical tests. The confirmation of species was performed by PCR using primers Y1 and Y2. The genetic diversity of Pectobacterium carotovoum was investigated by PCR ribotyping using primers G1/L1, which are complementary to conserved regions of the rRNA operon. Furthermore, the profiles obtained were compared by the Unweighted Pair Group Method. Results: The biochemical and physiological analysis demonstrated that the predominant pectolytic enterobacterium present in Morocco is Pectobacterium carotovorum subsp carotovorum. The specific confirmation of species P. carotovorum by PCR has yielded a 434 bp DNA fragment of the pelY gene with all isolates. Further, PCR amplification of the 16S-23S Intergenic spacer Region (ITS-PCR) has presented a specific pattern made of 2-6 fragments ranging from 300 bp to 800 bp. The UPGMA tree has shown that there is considerable genetic diversity in P. carotovorum strains, which can be divided into four distinct groups.

Bacillus thuringiensis: en el manejo del agente de la pudrición blanda de la papa Erwinia carotovora / Bacillus thuringiensis control of the potato soft rot Erwinia carotovora

En Colombia el cultivo de papa es el cuarto en importancia en la economía del país, y su producción alcanza las 300 millones de toneladas aproximadamente. Erwinia carotovora es una bacteria Gram negativa, anaeróbica facultativa causante de la pudrición blanda de la papa, puede llegar a generar hasta el 100% de daño en la cosecha, lo cual ocasiona grandes pérdidas económicas. Se ha establecido que la bacteria Bacillus thuringiensis es capaz de suprimir la virulencia de E. caratovora debido a que produce N-acil-homoserina-lactonasa, una potente enzima que degrada de N-acil-homoserinolactonas, que son indispensables en el mecanismo de quorum-sensing de E. caratovora. Esta circunstancia, puede ser una alternativa importante para el control de la enfermedad de la pudrición blanda de la papa. Considerando lo anterior, en este artículo se describe el proceso que emplea la bacteria Bacillus thuringiensis para inhibir la actividad de E. caratovora.

In Colombia the potato crop is the fourth in importance in the economy of the country, its production reached 300 million tons. Erwinia carotovora is a Gram-negative bacterium, facultative anaerobic which causes the soft rotting of the potato; it can potentially generate up to 100% damage in the crop, which causes large economic losses. It has been established that the bacterium Bacillus thuringiensis is able to suppress the virulence of E. caratovora because it produces N-acyl-homoserine-lactonasa, a powerful enzyme that degrades of N-acyl-homoserinolactonas, which are indispensable in the quorum-sensing mechanism of E. caratovora. This can be an important alternative for the control of the disease of the soft rotting of the potato. Considering the above, this article describes the process used by the bacterium B. thuringiensis to inhibit the activity of E. caratovora.

Changes in the biochemical constituents of carrot roots due to bacterial soft rot.

Carrot is a rich source of nutrients. The carrot contains carotene and lycopene, which gives bright color to the roots. The quality of the carrots was assessed based on the carotene, lycopene and other biochemical constituents like sugars, starch and protein. To study the effect of various isolates of the Erwinia carotovora var. carotovora on the above biochemical constituents, the pathogens were inoculated and the contents were analyzed separately at 1, 2, 3, 4, 5 days after inoculation. The contents of β-carotene increased significantly due to all the three isolates of the pathogen and the Coimbatore isolate recorded highest of 36.03 per cent. A same trend was also observed in the lycopene content with 93.55 per cent increase over control. The contents of total and reducing sugars were found to significantly increase due to inoculation with the pathogen. The starch content showed a decreasing trend in all the isolates tested. The maximum reduction of 62.98 per cent was observed in the roots inoculated with Coimbatore isolate.

Soft Rot of Rhizopus oryzae as a Postharvest Pathogen of Banana Fruit in Korea

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was 30degrees C. Sporangia were globose and 30~200 microm. Sporangiophores were usually straight, 8~20 microm, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and 90~110 microm. Sporangiospores were sub-globose or oval and 4~10 microm. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea.

Actividad antifúngica del quitosano y aceites esenciales sobre Rhizopus stolonifer -Ehrenb: Fr Vuill, agente causal de la pudrición blanda del tomate / Antifungal activity of chitosan and essential oils on Rhizopus stolonifer Ehrenb: Fr Vuill causal agent of soft rot of tomato

Rhizopus stolonifer es el agente causal de la pudrición blanda, enfermedad poscosecha que ocasiona pérdidas económicas importantes. Se han empleado fungicidas sintéticos como el dicloran para controlar a este microorganismo, sin embargo, se ha demostrado que los fungicidas representan un riesgo para el ambiente y la salud humana. Actualmente se buscan alternativas naturales para el control de las pudriciones poscosecha. Se evaluó in vitro e in situ el efecto antifúngico del quitosano y de los aceites esenciales de canela (Cinnamomum zeylanicum), clavo (Syzygium aromaticum) y tomillo (Thymus vulgaris) y dicloran sobre Rhizopus stolonifer. Los tratamientos más efectivos para inhibir in vitro a Rhizopus stolonifer fueron obtenidos con quitosano a 10 mg mL-1, con los tres aceites esenciales probados a la concentración de 0,3 mg mL-1, las mezclas de quitosano a 10 mg mL-1 con los aceites a 0,3 mg mL-1 y el dicloran a 1 mg mL-1. Los experimentos in situ mostraron que el tratamiento individual con quitosano fue el mejor para reducir el porcentaje de infección de los frutos de tomate (Lycopersicon esculentum) inoculados con Rhizopus stolonifer y que la mezcla de quitosano con aceites esenciales no mejora la actividad antifúngica. El quitosano y el dicloran fueron los mejores tratamientos para reducir la pérdida de peso de los frutos. Los tratamientos individuales con quitosano representan una alternativa natural para controlar la pudrición blanda en frutos de tomate.

Rhizopus stolonifer is the causal agent of soft rot, postharvest disease that causes important economic losses. Synthetic fungicides such as dichloran have been used to control this microorganism; however, it has been shown that fungicides represent a risk for the environment and human health. Actually, natural alternatives are looked for the control of postharvest rotting. In vitro and in situ experiments the antifungal effect of chitosan, essential oils of cinnamon (Cinnamomum zeylanicum), clove (Syzygium aromaticum), and thyme (Thymus vulgaris) and dichloran on Rhizopus stolonifer were evaluated. The most effective treatments for in vitro inhibition of Rhizopus stolonifer were obtained by quitosano to 10 mg mL-1, with the three essential oils proved to the concentration of 0.3 mg mL-1, the mixtures chitosan to 10 mg mL-1 with the oils at 0.3 mg mL-1 and dichloran at 1 mg mL-1. In situ experiments showed that the individual treatment with chitosan was the best to reduce the infection percentage of the tomato (Lycopersicon esculentum) fruits inoculated with Rhizopus stolonifer and chitosan mixture with essential oils did not improve its antifungal activity. Chitosan and dichloran were the best treatments to reduce the weight loss of the fruits. Individual treatments with chitosan represent a natural alternative for the control of soft rot on tomato fruits.

Microbiological Control of Bacterial Soft Rot Caused by Bacillus pumilus Od23 on Potato.

Potato soft rot, caused by Bacillus pumilus Od23, greatly affect potato tuber quality in storage and cultivars of Mali and indicated that it can affect all potato cultivars. Bacteria isolated from soil rhizosphere samples of healthy Malian indigenous trees were screened for their antagonistic effect against this pathogen. Three actinomycetes isolates (RoN, G1P, and N1F) were the most effective microbioagents in suppressing the growth of the pathogen. The biological control essay showed the possibility of controlling potato soft rot by these three actinomycetes isolates under conservation conditions. These treatments significantly decreased soft rot compared with the untreated potato tuber slices. The microbiological control results of this study suggest that the actinomycetes isolates RoN, G1P and and J1N are effective microbioagents in controlling soft rot of potato and could be considered as promising alternative to chemical products.

First Report of Rhizopus oryzae as a Postharvest Pathogen of Apple in Korea

Soft rot in apple caused by Rhizopus oryzae was found for the first time in Korea. A detailed description of the specimen is given along with its internal transcribed spacer rDNA sequence. The fungus was identified as Rhizopus oryzae based on the mycological characteristics, molecular data, and pathogenicity testing.

Podridão-mole em plantas de cebolinha causada por Pectobacterium carotovorumsubsp. carotovorum em Roraima / Soft rot of bunching onion plants caused by Pectobacterium carotovorumsubsp. carotovorum in Roraima, Brazil

A ocorrência de Pectobacterium carotovorum subsp. carotovorum (=Erwinia carotovora subsp. carotovora) em cebolinha (Allium fistulosum) é relatada pela primeira vez na região norte do Brasil. Até então sua ocorrência estava registrada apenas no Distrito Federal.

This is the first report of Pectobacterium carotovorum subsp. carotovorum (=Erwinia carotovora subsp. carotovora) causing soft rot of bunching onion (Allium fistulosum) plants in Roraima, Brazil. Its occurrence is reported only in Distrito Federal.

Rhizopus Soft Rot on Pear (Pyrus serotina) Caused by Rhizopus stolonifer in Korea

Rhizopus soft rot caused by Rhizopus stolonifer occurred on pears (Pyrus serotina) in the Jinju City Agricultural Products Wholesale Market in Korea from 2004 to 2005. The infection usually started from wounds due to cracking at harvest time. The lesions started as water-soaked, rapidly softened, then gradually expanded. The mycelia grew vigorously on the surface of the fruits and formed stolons. Colonies on potato dextrose agar at 25degrees C were white cottony to brownish black. Sporangia were globose, black and 90~120 microm in size. Sporangiophores were light brown and 480~2600 x 12~18 microm in size. Sporangiospores were globose to oval, brownish, streaked, and 8~14 x 6~10 microm in size. Columella were light brownish gray, hemispherical and 70~80 microm in size. On the basis of these symptoms, mycological characteristics and pathogenicity tests on host plants, the fungus was identified as Rhizopus stolonifer (Ehrenb.) Vuill. This is the first report of rhizopus soft rot on pear (P. serotina) caused by R. stolonifer in Korea.

Soft Rot of Tomato Caused by Mucor racemosus in Korea

A soft rot of fruits caused by Mucor racemosus occurred on cherry tomato collected in Agricultural Products Wholesale Market in Jinju, Korea. The disease infection usually occurred wounded areas after cracking of fruits. At first, the lesions started with water soaked and rapidly softened and diseased lesion gradually expanded. Colonies were white to brownish to gray in color. Sporangia were 32~54 microm in size and globose in shape. Sporangiophores were 8~14 microm in width. Sporangiospores were 5~12 x 4~8 microm in size, ellipsoidal to subglobose in shape. Columella was 27~42 microm in size, obovoid, ellipsoidal, cylindrical-ellipsoidal, slightly pyriform in shape. Chlamydospores were numerous in sporangiophores and barrelshaped when young, subglobose in old cultures. Optimum growth temperature was about 25degrees C. The fungus was identified as M. racemosus Fres. This is the first report of soft rot on cherry tomato caused by M. racemosus in Korea.

Soft Rot of Eggplant (Solanum melongena) Caused by Choanephora cucurbitarum in Korea

In April 2002 and 2003, soft rot on fruit of eggplant (Solanum melongena) caused by Choanephora cucurbitarum was observed in the experimental fields at Gyeongnam Agricultural Research and Extension Services in Korea. The disease began with water-soaking and dark-green lesions, and then the infected tissues were rapidly rotten. Sporangium was subglobose in shape and sized 40~130 microm. Monosporous sporangiola were elliptic, fusiform or ovoid, brown in color, and measured as 12~20 x 6~14 microm. Sporangiospores having three or more appendages were elliptic, fusiform or ovoid in shape, dark brown or brown in color, and sized 14~20 x 7~16 microm. The fungus grew well on potato dextrose agar between 15 and 40degrees C and its optimum growth temperature was 30degrees C. Based on morphological characteristics, the causal fungus of the fruit soft rot of eggplant was identified as C. cucurbitarum. This is the first report on the soft rot of S. melongena caused by C. cucurbitarum in Korea.

Fruit Soft Rot of Sweet Persimmon Caused by Mucor piriformis in Korea

A fruit soft rot caused by Mucor piriformis occurred on sweet persimmon storages in Jinju, Changwon and Gimhae, Gyeongnam province, Korea, 2003. The disease infection usually started from wounding after cracking of fruits. At first, the lesions started with water soaked and rapidly softened and diseased lesion gradually expanded. Colonies on potato dextrose agar at 20degrees C were whitish to olivaceous-buff Sporangia were globose, black and 96~153microm in size. Sporangiophores were 26~42microm in width. Sporangiospores were ellipsoid and 5.8~10.6x4.3~7.6microm in size. Columella was obovoid, cylindrical-ellipsoidal, pyriform, subglobose and 80~125microm in size. Optimal temperature for mycelial growth was 20degrees C on PDA. The causal organism was identified as M. piriformis. This is the first report of fruit soft rot on sweet persimmon caused by M. piriformis in Korea.

Rhizopus Soft Rot on Cherry Tomato Caused by Rhizopus stolonifer in Korea

A soft rot of fruits caused by Rhizopus stolonifer occurred on cherry tomato in Jinju City Agricultural Products Wholesale Market, Korea. The disease infection usually started from wounding after cracking of fruits. At first, the lesions started with water soaked and were rapidly softened and diseased lesion gradually expanded. The mycelia grew vigorously on the surface of fruits and formed stolons. Colonies on potato dextrose agar at 25degrees C were white cottony at first, becoming heavily speckled by the presence of sporangia and the browinish black, and spreading rapidly by means of stolons fired at various points to the substrate by rhizoids. Sporangia were 82.7x196.7 microm in size and globose or sub-globose with somewhat flattened base. The color of sporangia was white at first and then turned black with many spores, and never overhanging. Sporangiophores were 2.6~5.8x12.3~24.2 microm in width, smooth-walled, non-septate, light brown, simple, long, arising in groups of 3~5 from stolons opposite rhizoids. Sporangiospores were 8.2~18.8 microm long, irregular, round, oval, elongate, angular, and browinish-black streaked. Columella was 64.1x136.3 microm. brownish gray, and umberella-shaped when dehisced. The causal organism was identified to be R. stolonifer. This is the first report of Rhizopus soft rot on cherry tomato caused by R. stolonifer in Korea.

Occurrence of Rhizopus Soft Rot on Peach (Prunus persica var. vulgaris) Caused by Rhizopus nigricans in Korea

A soft rot of fruits caused by Rhizopus nigricans occurred on peach (Prunus persica var. vulgaris ) in The Chinju City Agricultural Products Wholesale Marke during in summer season of 2000. The disease infection usually started from wounding after harvest fruits, and then moved to outside. At first, the lesions started with water soaked and rapidly softened and diseased area gradually expanded. In severely infected film house, the rate of infected fruits reached 65.2%. Numerous sporangiospores were produced on the diseased fruits. Most of the sporangiospores were appeared to be readily dispersed in the air. The mycelia grew surface of fruits and produced stolons. Colonies on potato dextrose agar at 25~30degrees C white cottony at first becoming heavily speckled by the presence of sporangia and the browinish black at maturity, spreading rapidly by means of stolons fired at various points to the substrate by rhizoids. Sporangia were 85.3~243.5x53.4~219.2microm in size and were globose or sub-globose with. somewhat flattened base. The color of sporangia was white at first and then turned black with many spores, and never over-hanging. Sporangiophores were 8.9~36.6microm in width, smooth-walled, non-septate, light brown, simple, long, arising in groups of 3~5 from stolons opposite rhizoids. Sporangiospores was 9.7~24.8x5.9~15.8microm, irregular, round, oval, elongate, angular, and browinish-black streaked. Columella was 70.2x149.7microm. brownish gray, and umberella-shaped when dehisced. The causal organism was identified as. Rhizopus nigricans Lind on the basis of the morphiogical characteristics of the fungus. Rhizopus soft rot on peach (Prunus persica ) caused by the fungi has not been reported in Korea. This is the first report of rhizopus soft rot on peach caused by Rhizopus nigricans in Korea.

Observation of Soft-Rot Wood Degradation Caused by Higher Ascomyceteous fungi

The capability of higher ascomyceteous fungi to cause typical soft-rot decay for wood under laboratory conditions is reviewed and discussed. Fungi tested were extremely active in the decomposition of timbers. Scanning electron micrographs illustrated typical soft-rot decay pattern of higher wood decay ascomycetes, with the exception of H. trugodes that caused white-rot decay. Most of the fungi tested could be grouped as soft-rot fungi that showed typical soft-rot type II. Hypha confined primarily to the resin canals in softwoods or vessel elements in hardwoods and spread tracheid to tracheid via pits of cell wall to cell wall with mechanical force.