Occurrence of Stem Blight Caused by Pseudomonas extremorientalis on Pinellia ternata in China

Pinellia ternata is a perennial herbaceous plant, which tubers can be used for anti-inflammatory and has a significant position in Traditional Chinese Medicine (Marki et al. 1987). In April 2020, bacterial stem blight first occurred on P. ternata in Jingmen City (30°32′N, 111°51′E), Hubei Province, China. In the follow-up investigation, the disease also appeared in plantations of P. ternata in Qianjiang City, Tianmen City. Initial symptoms showed orange-red streak on the stem, then progressed into chlorotic and water-soaked lesions, which caused roots to be necrotic and leaves to stunting, fading, and wilting. In the end, the leaves withered, the stems rotted completely, and the incidence of plant collapse reached 20~30%. To isolate the plant pathogenic bacteria, twenty P. ternata plant samples with distinct chlorotic stem symptoms were obtained from two fields in Jingmen City. Symptomatic samples were cut to 1-cm-long pieces by sterile scalpel, then were streaked onto nutrient agar medium and grow at 28℃ for 48 h. Four pure typical aerobic, gram-negative bacteria were isolated by characterized with transparent, smooth, round, convex surfaces. The isolated colonies did not produce fluorescent pigments on King’s B medium. In addition, the isolates were positive for nitrate reduction, arabinose, mannitol, D-ribose, sucrose, D-sorbitol, and were negative for gelatin liquefaction, rhamnose, D-glucose, D-melibiose. These characteristics were identified as Pseudomonas extremorientalis (Ivanova et al. 2002). One representative colony ZJH1 was selected randomly for further verification. The 16s rRNA, gyrB, and rpoD regions were obtained with primers 27F/1492R (Weisburg et al. 1991), gyrB-Fps/ gyrB-Rps, and rpoD-Fps/ rpoD-Rps, respectively (Sarkar and Guttman. 2004). These sequences were deposited in GenBank as accession nos. MT459234.1, MT469887.1 and MT469886.1, which revealed 99% homology with P. extremorientalis strain BS2774 (accession nos. LT629708.1). The pathogenicity of P. extremorientalis strain ZJH1 was confirmed by using 3-month-old, healthy, greenhouse-grown P. ternata plants. The stems were stabbed and inoculated 10 μL of the bacterial suspension (108 CFU / ml), inoculating the same amount of sterile water as a control, repeated 5 times for each treatment. The plants were cultivated in a greenhouse at 28 °C and a humidity of 80%. Three days later, the stems showed necrosis, followed by the withered leaves and died plants, whereas the control had no symptoms. P. extremorientalis were reisolated and verified again from symptomatic plants, which was consistent with Koch's postulates. This experiment was repeated thrice to get the same result. To our knowledge, this is the first report of bacterial stem blight caused by P. extremorientalis on P. ternata in China. Stem blight caused by P. extremorientalis poses a significant threat to yield and marketability of P. ternata. Further research on selecting resistant variety and effective chemical control is needed. References: Ivanova, E. P., et al. 2002. Int J Syst Evol Micr. 2113:2120. https://doi.org/10.1099/00207713-52-6-2113 Marki, T., et al. 1987. Planta Med. 53:412. Sarkar, S. F., Guttman, D. S. 2004. Appl. Environ. Microbiol. 70:1999. https://doi.org/10.1128/AEM.70.4.1999-2012.2004 Weisburg, W. G., et al. 1991. J. Bacteriol. 173:697. https://doi.org/10.1128/jb.173.2.697-703.1991 F. F. Wang and Y. J. You contributed equally to this work. The author(s) declare no conflict of interest. Funding: National Modern Agricultural Industrial Technology System (grant no. CARS-21), Technology R&D Program of Enshi Tujia and Miao Autonomous Prefecture (grant no. D20190015), Science Funds for Young Scholar of Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences (grant no. 2019ZYCJJ01), Key R&D Program of Hubei Province (grant no. 2020BCA059), Key Technology R&D Projects of Hubei Agricultural Science and Technology Innovation Center (grant no. 2020-620-000-002-04)

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First Report of Blight on Pinellia ternata (Banxia) Caused by Choanephora cucurbitarum in China.

Plant Disease ◽

10.1094/pdis-12-20-2558-pdn ◽

2021 ◽

Author(s):

Fanfan Wang ◽

ting Mao ◽

Tao Tang ◽

Jie Guo ◽

Yuanyuan Duan ◽

...

Keyword(s):

Morphological Characteristics ◽

Hubei Province ◽

Agricultural Science ◽

Central China ◽

Molecular Characteristics ◽

Herbaceous Plant ◽

Pinellia Ternata ◽

First Report ◽

Agricultural Sciences ◽

Choanephora Cucurbitarum

Pinellia ternata (Thunb.) Makino ex Briet. (banxia, crow-dipper) is a perennial herbaceous plant native to China, Japan, and Korea. A member of the family Araceae, it is considered an invasive weed in parts of Europe and North America. In August 2020, P. ternata plants showing blight symptoms (8% incidence in a 30-ha field) were observed, near Qianjiang City (30°50′N, 112°92′E), Hubei Province, China. Brown water-soaked lesions first appeared on flowers followed by flower blight and leaf and stem rot during periods of more than 80% humidity (Supplementary figure 1). White, cottony mycelia grew from rotted tissues and produced sporangiophores with brown to black sporangiola. To identify the causal agent, 12 diseased samples were surface disinfested with 0.5% sodium hypochlorite and 75% ethyl alcohol, then plated on potato dextrose agar (PDA) maintained at 25°C. Ten fungal isolates were selected by hyphal tip isolation and placed on fresh PDA. White fungal colonies grew rapidly that later turned pale yellow and produced abundant sporangiola in 13 days. Sporangiophores were smooth, hyaline, aseptate, and produced monosporous sporangiola. Sporangiola were ellipsoid, indehiscent, pediculate, brown to dark brown, 8 to 16 × 14 to 21 μm (n = 50) in size, with visible longitudinal striations . Sporangia with a few or many sporangiospores were subglobose, pale brown to brown, and 55 to 165 μm (n = 40) in diameter. Sporangiospores were broadly ellipsoid, brown to pale brown, striate, 8 to 12 × 15 to 25 μm (n=30) in size, with hyaline polar appendages. Based on these morphological characteristics, the fungus was identified as Choanephora cucurbitarum (Berk. & Ravenel) Thaxt. (Kirk 1984). To confirm the identification, the strain QJFY1 was chosen for DNA sequencing. The internal transcribed spacer (ITS) region of rDNA and large subunit (LSU) region of ribosomal RNA were amplified with primers ITS1/ITS4 and NL1/LR3 (Walther et al. 2013) and the amplicons were sequenced. BLAST analysis of the 593bp sequences (accession no. MW295532) and the 699bp sequence（accession no. MW341527）showed ≥99.5% identity with C. cucurbitarum strains CBS 674.93 (GenBank accession no. JN943006.1 and JN939195.1; Supplementary figure 2). Based on morphological and molecular characteristics, the fungus was identified as C. cucurbitarum. Koch’s postulates were fulfilled by inoculating flowers of three healthy 30-day-old P. ternata plants with 50 μL of inoculum suspension (1 x 104 conidia/ml) obtained from 13-day old cultures of C. cucurbitarum isolate QJFY1. Another three plants treated with sterile distilled water served as controls. All plants were placed in a greenhouse with relative humidity of 90% for 2 days and thereafter placed in the glasshouse at 25 ± 1°C. After three days, symptoms similar to those seen under field conditions, were observed on inoculated plants and non-inoculated plants remained healthy. C. cucurbitarum was reisolated and identified by molecular characteristics (ITS and LSU) from inoculated plants. The experiment was repeated thrice with similar results. To our knowledge, this is the first report of Choanephora blight caused by C. cucurbitarum on P. ternata in China and worldwide. Hubei Province is one of the most important banxia producing areas in China and C. cucurbitarum can pose a new threat to banxia production. Our results provide a basis to develop effective measures to manage this disease. References: Kirk, P. M. 1984. Mycol. Pap. 152:1. Walther, G., et al. 2013. Persoonia 30:11. http://dx.doi.org/10.3767/003158513X665070 Acknowledgements Science Funds for Young Scholar of Institute of Chinese Herbal Medicines, Hubei Academy of Agricultural Sciences (grant no. 2019ZYCJJ01), Key Research and Development Program of Hubei Province (grant no. 2020BCA059), Support Plan of Hubei Academy of Agricultural Sciences (grant no. 2019fcxjh09), Key Laboratory of Integrated Management of Crops of Central China, Ministry of Agriculture, P. R.China / Hubei Key Laboratory of Crop Disease, Insect Pests and Weeds Control (grant no. 2019ZTSJJ6), Hubei Agricultural Science and Technology Innovation Center Project (grant no.2019-620-003-001)

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Occurrence of Dickeya fangzhongdai Causing Soft Rot of Banxia (Pinellia ternata) in China

Plant Disease ◽

10.1094/pdis-01-21-0030-pdn ◽

2021 ◽

Author(s):

Fanfan Wang ◽

Tao Tang ◽

ting Mao ◽

Jie Guo ◽

XiaoLiang Guo ◽

...

Keyword(s):

16S Rdna ◽

Soft Rot ◽

Negative Control ◽

Reca Gene ◽

Bacterial Suspension ◽

Herbaceous Plant ◽

Pathogenicity Test ◽

Sterile Water ◽

Pinellia Ternata ◽

Traditional Chinese Herbal Medicine

Banxia [Pinellia ternata (Thunb.) Breit., Araceae] is a perennial herbaceous plant, where the tuber is commonly used in traditional Chinese herbal medicine. In the summer of 2020, an outbreak of soft rot of Banxia was observed in Zhugentan Town (30°50′N, 112°91′E), Qianjiang City, Hubei Province, with about 56% percentage of infected plants. Symptomatic plants initially appeared with small water-soaked spots on leaves that progressed into extensive translucent spots when facing a light source. The bacteria further spread to the stems and tubers. Infected tubers appeared normal, but inner macerated inclusions exuded when touched. The whole plant was macerated and collapsed within a few days. Ten leaves with typical symptoms were obtained from a diseased field, by surface sterilizing in 75% ethanol for 30 s and 0.3% NaClO for 5 min, washing the tissue sections three times in sterile water. Small pieces of tissue (5 × 5 mm) were removed from lesion borders, plated on nutrient ager medium, and cultivated at 37 ℃ for 48 h. Five representative isolates were selected for further identification. Colonies were all smooth and transparent. In addition, these strains were Gram-negative, and had the ability to reduce D-arabinose, melibiose, galactose, raffinose, rhamnose, inositol, and mannitol, but not reduce 5-keto-D-gluconate, L-xylose, amygdalin, and sorbitol. Genomic DNA was extracted from isolate stain ZG5. The 16S rDNA gene, recombinase A (recA) gene, and DNA polymerase III subunits gamma and tau (dnaX) were amplified by PCR with the primers 27f/1492r (Weisburg et al. 1991), recF/recR (Waleron et al. 2002), and dnaXf/dnaXr (Sławiak et al. 2009), respectively. The PCR products were sequenced, then submitted to GenBank (GenBank MW332472, MW349833, MW349834, respectively). BLAST search showed that the sequences of 16S rDNA, recA, and dnaX respectively matched ≥99% with D. fangzhongdai strains DSM 101947 (CP025003), QZH3 (CP031507), and PA1 (CP020872). Pathogenicity tests were performed on 10 healthy, 3-month-old P. ternate plants. Five plants were injected with 20 μl of bacterial suspension (108 CFU/ml) of isolate ZG5, and other plants were injected with sterile water as a negative control. All tested plants were incubated at 28 ℃ and individually covered with a plastic bag. After 24 h, soft rot symptoms all appeared on the pathogen-inoculated leaves, whereas no symptoms on the control leaves. The pathogenicity test was repeated three times and obtained same results. Koch’s postulates were fulfilled by reisolating D. fangzhongdai from inoculated plants. Meanwhile, PCR were performed on the reisolated bacteria as above described, and the pathogen was identified and confirmed as D. fangzhongdai. Here we report that D. fangzhongdai causes soft rot of P. ternata in China. The disease progressed very rapidly, and reduced the yield and quality of tubers. Thus, more research is needed to implement effective strategies to manage this disease.

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Usages of Salvia officinalis Boiled Water Extract for Pathogenic Escherichia coli Exclusion at Elevated Region

Biotechnology and Bioprocessing ◽

10.31579/2766-2314/026 ◽

2021 ◽

Vol 2 (3) ◽

pp. 01-03

Author(s):

Sherifa Sabra

Keyword(s):

Escherichia Coli ◽

Pathogenic Bacteria ◽

Water Extract ◽

Salvia Officinalis ◽

Bacterial Suspension ◽

Water Extracts ◽

Pathogenic Escherichia Coli ◽

Chemical Content ◽

Boiled Water ◽

Chemical Contents

The aim was for tryout using daily regular Salvia officinalis boiled water extracts in "Arab and Saudi Society", especially at elevated region "Taif". That to prove its ability for pathogenic Escherichia coli exclusion and had antibiotic resistance. This could prove strength of chemical content and adherence of "Arab People" to use as regular and daily to stabilize body health and protect against pathogenic bacteria. Salvia officinalis was purchased from pharmacy at "Taif" and boiled water extract was made. Pathogenic Escherichia coli was obtained from a "Licensed Health Center"; culture was made and suspensions. Tryout by boiled water extract were added to bacterial suspension and then were kept in incubator. The samples were taken at hours (1, 3, 5, 7, 9, 11, 13, 15, 17 and 19); were cultured and were kept for 48 hours at 37 °C. The exclusion percent's had determined, Escherichia coli exclusion mean percentages rose 5% at third hour and then increased 7% at fifth hour and at ninth hour was 8%. Then it decreased at the eleventh hour and thirteenth hour (2% and 3%), then rose at the fifteenth hour 10%. It decreased 5% at the seventeenth hour, and then returned and rose at the nineteenth hour 12%. It was concluded Salvia officinalis boiled water extracts effects on pathogenic Escherichia coli exclusion was found during one growth bacteria cycle, indicated the characteristics of chemical contents and good daily habit. It was recommend continuing as "Arabian Habit" Salvia officinalis boiled water extracts for health and protection stability.

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Effect of Traditional Chinese Herbal Medicine with Antiquorum Sensing Activity onPseudomonas aeruginosa

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2013/648257 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 11

Author(s):

Weihua Chu ◽

Shuxin Zhou ◽

Yan Jiang ◽

Wei Zhu ◽

Xiyi Zhuang ◽

...

Keyword(s):

Herbal Medicine ◽

Chinese Herbal Medicine ◽

Bacterial Infections ◽

Pathogenic Bacteria ◽

Cell Communication ◽

Herbal Medicines ◽

Chinese Herbal Medicines ◽

Traditional Chinese Herbal Medicine ◽

Chinese Herbal ◽

Traditional Chinese Herbal Medicines

Traditional Chinese herbal medicines (TCHMs) were tested for their ability of antiquorum sensing. Water extracts ofRhubarb, Fructus gardeniae, and Andrographis paniculatashow antiquorumsensing activity when usingChromobacterium violaceumCV12472 as reporter; the sub-MIC concentrations of these TCHMs were tested against AHL-dependent phenotypic expressions of PAO1. Results showed significant reduction in pyocyanin pigment, protease, elastase production, and biofilm formation in PAO1 without inhibiting the bacterial growth, revealing that the QSI by the extracts is not related to static or killing effects on the bacteria. The results indicate a potential modulation of bacterial cell-cell communication,P. aeruginosabiofilm, and virulence factors by traditional Chinese herbal medicine. This study introduces not only a new mode of action for traditional Chinese herbal medicines, but also a potential new therapeutic direction for the treatment of bacterial infections, which have QSI activity and might be important in reducing virulence and pathogenicity of pathogenic bacteria.

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Evaluation of methods for isolation of DNA for polymerase chain reaction (PCR)-based identification of pathogenic bacteria from pure cultures and water samples

Water Science & Technology ◽

10.2166/wst.2008.453 ◽

2008 ◽

Vol 58 (5) ◽

pp. 995-999 ◽

Cited By ~ 9

Author(s):

K. Horáková ◽

H. Mlejnková ◽

P. Mlejnek

Keyword(s):

Polymerase Chain Reaction ◽

Water Samples ◽

Pathogenic Bacteria ◽

Pcr Amplification ◽

Bacterial Suspension ◽

Chain Reaction ◽

Alkaline Lysis ◽

Bacterial Dna ◽

Pure Cultures ◽

Polymerase Chain

Polymerase chain reaction (PCR) provides a reliable detection of pathogenic bacteria in water samples. However, this method can be adversely influenced by the purity of the DNA template. This is a particularly important obstacle when the bacterial DNA is directly extracted from water samples. In this study we compared the suitability of 8 different methods for isolation of bacterial DNA from pure cultures and 10 different methods for isolation of DNA from water samples. The quality of extracted DNA was assessed by PCR amplification of target sequences derived from uid (E. coli and Shigella sp.), tuf (Enterococcus sp.) and hns (Salmonella sp.). Results indicated that there are differences among the methods tested and only a few of them gave satisfactory results. The method based on alkaline lysis of bacterial suspension, which was developed in our laboratory, seemed to be efficient enough for the detection of bacteria from pure cultures. Detection of bacteria directly from water samples was more difficult. The modified method developed by Slusarenko was found as the best of the tested methods.

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First Report of Bacterial Wilt Caused by Ralstonia solanacearum on Plectranthus amboinicus in Martinique

Plant Disease ◽

10.1094/pdis-12-20-2622-pdn ◽

2021 ◽

Author(s):

Peninna Deberdt ◽

Gilles Cellier ◽

Régine Coranson-Beaudu ◽

Mathis Delmonteil--Girerd ◽

Joanye Canguio ◽

...

Keyword(s):

Bacterial Wilt ◽

Ralstonia Solanacearum ◽

Disease Incidence ◽

Bacterial Suspension ◽

Diagnostic Pcr ◽

Tomato Plants ◽

First Report ◽

Initial Symptoms ◽

Plectranthus Amboinicus ◽

Negative Controls

Plectranthus amboinicus, commonly known as Gwo ten in the French West Indies (Martinique), is a semi-succulent perennial plant of the Lamiaceae family. This aromatic plant wich is widespread naturally throughout the tropics is of economic importance because of the therapeutic and nutritional properties attributed to its natural phytochemical compounds wich are highly valued in the pharmaceutical industry. In March 2019, wilted P. amboinicus plants intercropped with tomato plants (cv. Heatmaster) in order to reduce the insect-pest damages on tomato, were observed in a field located at the CIRAD experimental station in Lamentin, Martinique (14.663194 N, -60.999167 W). Average disease incidence of 65.74% was recorded on P. amboinicus, in 3 plots with an area of 22.04 m2. The initial symptoms observed were irregular, black, necrotic lesions on leaves. After 10 days, plants wilted and black stripes were observed on stems. Within 4 weeks, more than 50% of plants were fully wilted. Longitudinal stem sections of the wilted plants showed brown vascular discoloration. The cut stems of the wilted plants released a whitish bacterial ooze in water. In all, 108 stem sections were collected, surface disinfected with 70% ethanol and each was crushed in 2 mL of Tris-buffer, then processed for bacterial isolation by plating on modified Semi-Selective Medium from South Africa SMSA (Engelbrecht 1994). Typical Ralstonia solanacearum colonies grew on SMSA medium for 100 of the 108 samples after incubation for 48h at 28°C and were identified as Ralstonia solanacearum using diagnostic PCR with 759/760 primers (Opina et al. 1997). A phylotype-specific multiplex PCR (Fegan and Prior 2005) classified all the strains in R. solanacearum Phylotype IIA. A subset of 11 strains was selected for sequevar identification. All the strains were identified as sequevar I-39 (100% nucleotide identity with strain ANT92 - Genbank accession EF371828), by partial egl sequencing (Fegan and Prior 2005) (GenBank Accession Nos. MT314067 to MT314077). This sequevar has been reported to be widespread in the Caribbean and tropical America on vegetable crops (particularly on tomato), but not on P. amboinicus (Deberdt et al. 2014; Ramsubhag et al. 2012; Wicker et al. 2007). To fulfil Koch’s postulates, a reference strain, isolated from diseased P. amboinicus (CFBP 8733, Phylotype IIA/sequevar 39), was inoculated on 30 healthy P. amboinicus plants. A common tomato cultivar grown in Martinique (cv. Heatmaster) was also inoculated on 30 plants with the same bacterial suspension. Three-weeks-old plants of both crops grown in sterilized field soil were inoculated by soil drenching with 20 ml of a calibrated suspension (108 CFU/mL). P. amboinicus and tomato plants drenched with sterile water served as a negative controls. Plants were grown in a fully controlled environment at day/night temperatures of 30–26°C ± 2°C under high relative humidity (80%). The P. amboinicus plants started wilting 9 days after inoculation, and within four weeks 60% of the P. amboinicus plants had wilted. The tomato plants started wilting 5 days after inoculation with 62% of wilted plants within four weeks. R. solanacearum was recovered from all symptomatic plants on modified SMSA medium. No symptoms were observed and no R. solanacearum strains were isolated from negative controls plants. To our knowledge, this is the first report of R. solanacearum causing bacterial wilt on Gwo ten (P. amboinicus) in Martinique. The importance of this discovery lies in the reporting of an additional host for R. solanacearum, which can be associated with other crops as tomato crop in order to reduce the abundance of insect-pests. Further studies need to be conducted to assess the precise distribution of bacterial wilt disease on P. amboinicus in Martinique and to develop a plan of action avoiding its association with R. solanacearum host crops as tomato for reducing epidemic risk.

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Selection Resistance of Rice Germplasm Accessions to Bacterial Leaf Blight

Buletin Plasma Nutfah ◽

10.21082/blpn.v20n2.2014.p65-76 ◽

2016 ◽

Vol 20 (2) ◽

pp. 65 ◽

Cited By ~ 1

Author(s):

Dini Yuliani ◽

Rina H. Wening ◽

NFN Sudir

Keyword(s):

Leaf Blight ◽

Xanthomonas Oryzae ◽

Bacterial Leaf Blight ◽

Resistant Variety ◽

Bacterial Suspension ◽

Wet Season ◽

Isogenic Lines ◽

Resistant Varieties ◽

Cropping Seasons ◽

Germplasm Accessions

Seleksi Ketahanan Aksesi Plasma Nutfah Padi terhadap Hawar Daun Bakteri. Dini Yuliani, Rina H. Wening, dan Sudir. Usaha budi daya tanaman padi di Indonesia selalu dihadapkan pada berbagai kendala, di antaranya serangan penyakit hawar daun bakteri (HDB) yang disebabkan oleh bakteri Xanthomonas oryzae pv. oryzae (Xoo). Pengendalian penyakit HDB dengan varietas tahan merupakan salah satu teknik yang murah dan mudah dilakukan oleh petani padi. Aksesi plasma nutfah sebagai sumber tetua untuk perakitan varietas tahan perlu diketahui reaksi ketahanannya terhadap penyakit HDB. Penelitian ini bertujuan untuk menyeleksi ketahanan aksesi plasma nutfah terhadap penyakit HDB patotipe III, IV, dan VIII. Penelitian dilaksanakan di Kebun Percobaan Balai Besar Penelitian Tanaman Padi di Sukamandi, Subang, Jawa Barat pada Musim Hujan 2012/2013 dan Musim Kemarau 2013 dengan Rancangan Acak Terpisah. Petak utama adalah tiga patotipe Xoo, yaitu patotipe III, IV, dan VIII. Sedangkan anak petak adalah materi yang diuji, yaitu 20 aksesi plasma nutfah dan tiga varietas pembanding. Sebanyak 20 rumpun tanaman per petak diinokulasi Xoo dengan metode pengguntingan. Inokulasi dilakukan pada saat pertanaman menjelang stadium primordia. Ujung-ujung daun digunting sepanjang kira-kira 10 cm dari ujung daun dengan gunting inokulasi yang berisi suspensi bakteri Xoo umur 48 jam dengan kepekatan 108 cfu. Pengamatan keparahan penyakit HDB dilakukan dengan mengukur panjang gejala terpanjang pada umur dua, tiga, dan empat minggu setelah inokulasi. Hasil pengujian ketahanan terhadap HDB patotipe III, IV, dan VIII diperoleh tiga aksesi plasma nutfah yang berasal dari galur isogenik menunjukkan keparahan penyakit HDB tidak berbeda nyata dengan varietas pembanding tahan Angke pada dua musim tanam. Galur isogenik tersebut, yaitu IRBB 55, IRBB 60, dan IRBB 61. Ketiga galur isogenik tersebut dapat dijadikan tetua tahan dalam perakitan varietas unggul baru tahan HDB. AbstrakRice cultivation in Indonesia has been faced with many obstacles, including the attack of bacterial leaf blight (BLB) that caused by bacteria Xanthomonas oryzae pv. oryzae (Xoo). Resistant variety was considered as the cheap technique to control BLB disease and could be used by rice farmers. Germplasm accessions as a source to build resistant varieties must be known their resistance to BLB disease. This study aimed at selecting the resistance germplasm accessions to BLB pathotype III, IV, and VIII. The study was conducted at the Experimental Station of the Indonesian Center for Rice Research in Sukamandi, Subang, West Java at wet season 2012/2013 and dry season 2013 with Split Plot Design. The main plot was three pathotypes Xoo i.e. pathotype III, IV, and VIII. The subplot was 20 germplasm accessions and three check varieties. A total of 20 hills of rice plants per plot were inoculated by Xoo with cutting method. Inoculation was conducted before the primordia stage. Inoculation of bacterial suspension containing Xoo aged 48 hours at a concentration of 108 cfu. Observations BLB disease severity was done by measuring the longest length of symptoms at the age of two, three, and four weeks after inoculation (WAI). The result showed that three germplasm accessions from near isogenic lines were not significantly different with the check varieties (Angke) in their resistance to Xoo pathotype III, IV, and VIII in two cropping seasons. The isogenic lines were IRBB 55, IRBB 60, and IRBB 61 can be used in the assembly of resistant new varieties to BLB.

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First Record of Bacterial Blight Caused by Pseudomonas syringae pv. syringae on Pyracantha coccinea and an Amelanchier sp. in Bulgaria

Plant Disease ◽

10.1094/pdis-92-8-1251c ◽

2008 ◽

Vol 92 (8) ◽

pp. 1251-1251 ◽

Cited By ~ 1

Author(s):

S. G. Bobev ◽

S. Baeyen ◽

J. Van Vaerenbergh ◽

M. Maes

Keyword(s):

Pseudomonas Syringae ◽

Pathogenic Bacteria ◽

Pcr Amplification ◽

First Record ◽

Bacterial Suspension ◽

Bacterial Strains ◽

First Occurrence ◽

Symptomatic Tissue ◽

And Control ◽

Pyracantha Coccinea

During the spring and summer months of 2004 and 2005, sporadic damage on individual shrubs of Pyracantha coccinea and an Amelanchier sp. were observed at two locations in the region of Plovdiv, Bulgaria. Symptoms initially were expressed as blossom blight and subsequently expanded to the shoots and branches, forming cankers on the supplying wood. In both years, a fluorescent gram-negative bacterium was isolated from diseased tissues onto King's B medium. The bacterial strains were levan positive and oxidase and arginine dihydrolase negative. They were able to induce a typical hypersensitive response on tobacco plants (cv. Samsun), but failed to rot potato slices. Pathogenicity of the strains was confirmed by puncture-inoculating detached shoots from both hosts and immature cherry and pear fruits with a bacterial suspension (108 CFU/ml, 50 μl per wound, and 3 replicates). Controls were punctured with sterile water. The inoculated plant material was maintained at room temperature (22 to 25°C) in plastic pots and covered with polyethylene bags for the first 48 h after inoculation. The inoculated and control subjects were kept under the same conditions as before inoculation. Except for the controls, slowly expanding but well defined necrotic lesions around the inoculation points were observed within the next 5 to 7 days. Bacteria reisolated from symptomatic tissue were identical to the initial cultures. On the basis of the symptoms and results from all laboratory tests, the bacterium was considered to be Pseudomonas syringae pv. syringae (1). PCR amplification of the 752-bp syrB fragment (2) confirmed the identification. To our knowledge, this is the first occurrence of P. syringae pv. syringae on Pyracantha coccinea and an Amelanchier sp. in Bulgaria, and most probably, this pathogen will play a more significant role within the rosaceous group because of a rising number of the cultivated ornamental species. References: (1) N. W. Schaad et al., eds. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001. (2) K. N. Sorensen et al. Appl. Environ. Microbiol. 64:226, 1998.

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First Report of Acidovorax avenae subsp. avenae Causing Bacterial Leaf Stripe of Strelitzia nicolai

Plant Disease ◽

10.1094/pdis-03-11-0160 ◽

2011 ◽

Vol 95 (11) ◽

pp. 1474-1474 ◽

Cited By ~ 2

Author(s):

T. E. Seijo ◽

N. A. Peres

Keyword(s):

Pathogenic Bacteria ◽

Fatty Acid Analysis ◽

South Florida ◽

Metabolic Phenotype ◽

Bacterial Suspension ◽

Rrna Gene ◽

First Report ◽

Plastic Bags ◽

Young Leaves ◽

Symptomatic Tissue

White bird of paradise (Strelitzia nicolai Regel & K. Koch) is a commonly grown ornamental in central and south Florida. Each summer of 2004 to 2007, a reoccurring disease was observed at a commercial nursery in central Florida. Diseased plants had brown, necrotic stripes between the lateral leaf veins, which usually appeared along the midvein and spread toward the leaf edge. Lesions developed on the youngest leaves as they emerged from the central whorl. During 2004 and 2005, 20 symptomatic leaves were sampled. A white, nonfluorescent bacterium was consistently isolated from symptomatic tissue. It induced a hypersensitive response (HR) on tomato, grew at 41°C, and was identified as a Acidovorax sp. based on fatty acid analysis and as Acidovorax avenae subsp. avenae by Biolog metabolic phenotype analysis (similarity 0.76 to 0.86). A partial 16S rRNA gene sequence (1,455 bp) (Accession No. EF418616) was identical to four sequences in the NCBI (National Center for Biotechnology Information) database: one from A. avenae subsp. avenae and three from A. avenae of undetermined subspecies. To confirm pathogenicity, a bacterial suspension (O.D590 = 0.1) was applied to fill the central whorl (~0.5 to 1 ml) of potted S. nicolai. Plants were incubated for 7 to 10 days inside plastic bags at ambient temperature. Plants were inoculated individually with five strains of A. avenae subsp. avenae, four from S. nicolai, and one from corn (ATCC19860). Two to nine plants per strain were inoculated in each experiment. All strains were tested at least twice and noninoculated control plants were included. Symptoms were reproduced on the emerging leaf of 50 to 100% of inoculated plants with all five A. avenae subsp. avenae strains. No symptoms were observed on the controls. The bacteria recovered from symptomatic tissue were confirmed to be A. avenae subsp. avenae. Corn seedlings were inoculated as described above, except that entire seedlings were sprayed. Water-soaked lesions along the length of older leaf blades developed in 4 to 7 days. Only the corn strain was pathogenic (>80% of seedlings symptomatic), indicating host specificity. To our knowledge, this is the first report of A. avenae subsp. avenae infecting S. nicolai. In 1971, Wehlburg (2) described the same symptoms on orange bird of paradise (S. reginae) as being caused by a nonfluorescent Pseudomonas sp. This report likely describes the same disease since the published description is consistent with symptoms caused by A. avenae subsp. avenae. The pathogen reported by Wehlburg (2) had one polar flagellum, reduced nitrate, produced oxidase and a HR, and utilized arabinose, but not sucrose or arginine, characteristics consistent with those of A. avenae subsp. avenae (1). The only difference was A. avenae subsp. avenae has a delayed positive starch hydrolysis (1), whereas Welhburg's strain was negative. This disease occurs mainly on young leaves when plants receive daily overhead irrigation. Incidence can be as high as 40%, occasionally causing mortality, but even mild symptoms affect appearance and reduce marketability as an ornamental. References: (1) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2001. (2) C. Wehlburg. Plant Dis. Rep. 55:447, 1971.

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First Report of Pectobacterium carotovorum subsp. carotovorum Causing Soft Rot of Orostachys japonica in Korea

Plant Disease ◽

10.1094/pdis-10-13-1039-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 989-989 ◽

Cited By ~ 2

Author(s):

W. Cheon ◽

Y. H. Jeon

Keyword(s):

16S Rrna ◽

Pathogenic Bacteria ◽

Sequence Similarity ◽

Soft Rot ◽

Bacterial Suspension ◽

Pectobacterium Carotovorum ◽

First Report ◽

Biolog System ◽

Carotovorum Subsp ◽

Physiological Tests

Orostachys japonica (Maxim) A. Berger is an important traditional medicine in Korea. The extract of this plant has antioxidant activity and suppresses cancer cell proliferation (1). From summer through fall of 2012 and 2013, a high incidence (~10% to 30%) of disease outbreaks of all plants characterized by water-soaked lesions and soft rot with a stinky odor was observed in cultivated O. japonica around Uljin (36°59′35.04″N, 126°24′1.51″E), Korea. Water-soaked lesions were first observed on the stem base of plants. Subsequently, the plants collapsed, although the upper portion remained asymptomatic. Thereafter, the lesions expanded rapidly over the entire plant. To isolate potential pathogens from infected leaves, small sections (5 to 10 mm2) were excised from the margins of lesions. Ten bacteria were isolated from ten symptomatic plants. Three representative isolates from different symptomatic plants were used for identification and pathogenicity tests. Isolated bacteria were gram negative, pectolytic on crystal violet pectate agar, nonfluorescent on King's medium B, and elicited a hypersensitive response in tobacco plants. All isolates caused soft rot of potato tubers. These isolates also differed from isolates of Erwinia chrysanthemi (Ech) that they were insensitive to erythromycin and did not produce phosphatase. These isolates differed from known strains of E. carotovora subsp. atroseptica in that they did not produce reducing substances from sucrose (2). Use of the Biolog GN microplate and the Release 4.0 system identified the isolate as Pectobacterium carotovorum subsp. carotovorum with 81.2% similarity. The 16S rRNA of the isolated bacteria was amplified by PCR and sequenced as described by Weisburg et al. (3). A BLAST analysis for sequence similarity of the 16S rRNA region revealed 99% similarity with nucleotide sequences for P. carotovorum subsp. carotovorum isolates (KC790305, KC790280, JF926758, JX196705, and AB680074). The pathogenicity of three bacterial isolates was examined on three 2-year-old O. japonica plants by adding 50 μl of a bacterial suspension containing 108 CFU/ml when wounding the leaves with sterile needles. Ten control plants were inoculated with sterilized water. After inoculation, plants were maintained in a growth chamber at 25°C with relative humidity ranging from 80 to 90%. After 2 to 3 days, tissue discoloration, water-soaked lesions, and soft rot developed around the inoculation point. Severe symptoms of soft rot and darkening developed on leaves of inoculated plants within 3 to 5 days after inoculation. All controls remained healthy during these experiments. The bacterial strains re-isolated from the parts of the leaf showing the symptoms and identified as P. carotovorum subsp. carotovorum on the basis of the biochemical and physiological tests, as well as Biolog system. The results obtained for pathogenicity, Biolog analysis, and molecular data corresponded with those for P. carotovorum subsp. carotovorum. To our knowledge, this is the first report of the presence of P. carotovorum on O. japonica in Korea. References: (1) C.-H. Kim et al. Kor. J. Med. Crop Sci. 11:31, 2003. (2) N. W. Schaad et al. Erwinia Soft Rot Group. Page 56 in: Laboratory Guide for Identification of Plant Pathogenic Bacteria. 3rd ed. N. W. Schaad et al. eds. American Phytopathological Society, St. Paul. MN, 2001. (3) W. G. Weisburg et al. J. Bacteriol. 173:697, 1991.

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