Yeast Peptone Glucose Agar Research Articles

Potential of Bacillus subtilis potato isolate as biocontrol agent of Xanthomonas oryzae pv. oryzae and candidate for nanosuspension formula

Abstract. Djatmiko HA, Kurniawan DW, Prihatiningsih N. 2022. Potential of Bacillus subtilis potato isolate as biocontrol agent of Xanthomonas oryzae pv. oryzae and candidate for nanosuspension formula. Biodiversitas 23: 3313-3317. Bacillus subtilis potato isolate was able to be an antagonist of plant pathogens. The aims of this study were (i) to examine the potential of potato isolate B. subtilis as a control for Xanthomonas oryzae pv. oryzae (Xoo) as a pathogen rice bacterial leaf blight, (ii) determine the inhibition mechanism of their isolates, (iii) evaluate the best B. subtilis to make nanosuspension formula. The method was carried out in a completely randomized design with 5 treatments of B. subtilis potato isolates B46, B209, B211, B298, and B315, repeated 4 times. Xoo and five B. subtilis were grown in nutrient broth medium in a shaker. Xoo and B. subtilis were grown in yeast peptone glucose agar medium by the diffusion method. Xoo was inoculated on medium, and then a 5 mm diameter filter paper immersed with B. subtilis suspension was placed on the medium. The best B. subtilis as a controller was used to formulate into nanosuspension. The variables were zone of inhibition, inhibition mechanism and antibiosis index. The results showed that only three B. subtilis were able to inhibit the growth of Xoo, namely B211, B298 and B315 isolates. The highest (10 mm) inhibition zone was recorded by B. subtilis B315 isolate. The mechanism of inhibition of the three isolates of B. subtilis against Xoo was bacteriostatic. The antibiosis index of B. subtilis B315 against Xoo was 1 (strong). The selected B. subtilis B315 was developed as a nanosuspension formula with inhibition zone of 2.1 mm and antibiosis index was 0.42.

CHARACTERIZATION OF EGGPLANT ENDOPHYTE BACTERIA AND RHIZOBACTERIA AS WELL AS THEIR ANTAGONISTIC ABILITY AGAINST Ralstonia solanacearum

Characterization of eggplant endophyte bacteria and rhizobacteria as well as their antagonistic ability against Ralstonia solanacearum. Bacterial wilt caused by Ralsonia solanacearum is one of important diseases causing severe loses in eggplant production. Various strategies were used to manage bacterial wilt, including planting resistant varieties, soil amandement, and soil solarization. However, management of R. solanacearum in eggplant by using endophytic bacteria and rhizobacteria were not been done that much. The objective of this study was to: (1) characterization of endophytic and rhizobacteria; (2) determines the inhibition ability of endophytic and rhizobacteria isolates against R. solanacearum pathogen on eggplant. The laboratory experiment was arranged in completely randomized design with 5 treatments and 5 replications. The double layer method using yeast peptone glucose agar (YPGA) medium was used in vitro test. Based on the morphological characteristics these isolates were suspected as a member of genus Bacillus. Among the isolates used in this study, TK isolate showed the best capability to inhibit growth of R. solanacearum.

PM 7/21 (2) Ralstonia solanacearum, R. pseudosolanacearum and R. syzygii (Ralstonia solanacearum species complex)

Specific scopeThis Standard describes a diagnostic protocol for Ralstonia solanacearum, Ralstonia pseudosolanacearum and Ralstonia syzygii, i.e. phylotype/sequevar strain in the Ralstonia solanacearum Species Complex (RSSC).It should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.Specific approval and amendmentApproved in 2003‐09. First revised in 2018‐02.

Bacterial Canker of Mango, Mangifera indica, Caused by Xanthomonas citri pv. mangiferaeindicae, Confirmed for the First Time in the Americas

In June 2015, symptoms of what appeared to be bacterial canker (also known as bacterial black spot) were observed on mature fruits of mango, Mangifera indica, in the vicinity of Boynton Beach and Lake Worth, FL. Star-shaped lesions up to 2 cm in diameter erupted from the surfaces of 'Keitt', 'Haden', 'Springfels', and 'Lemon Zest' fruit, and oozed a sticky, clear exudate; symptoms were not observed on leaves or twigs. From lesions, a nonpigmented bacterium was recovered on yeast-peptone-glucose agar (YPGA) and characterized with efp and dnaK, two housekeeping genes used by Bui Thi Ngoc et al. (2010) to classify pathovars of X. citri. Amplicons from a representative isolate were sequenced (KU746336 and KU746337) and maximum likelihood analyses (Tamura-Nei model) with MEGA 6.06 placed the isolate among strains of Xanthomonas citri pv. mangiferaeindicae (Xcm). In incubator studies (30°C day, 26°C night, 12-h photoperiod), the mesophyll of leaves on potted 'Keitt' and 'Haden' plants were injected with a hypodermic needle and 1 × 105 CFU/ml of the isolate from 18-h YPGA colonies suspended in sterile deionized H2O. After 7 days, black lesions developed on inoculated leaves, but not on leaves injected with sterile deionized H2O. Diagnostic amplicons for Xcm were generated for isolates recovered from the lesions, and similar results were obtained when the experiment was repeated a second time. Bacterial canker is widespread in the Eastern Hemisphere (Gagnevin and Pruvost 2001), moved recently to West Africa (Pruvost et al. 2011), and was recently reported in Hawaii (Yasuhara-Bell et al. 2013). However, this is the first report of the disease in the Americas (prior reports of the disease in the region were erroneous (Ah-You et al. 2007)). Only two of the top 10 mango-producing countries are in the Americas, but the top exporter (Mexico) and three other countries in the region are among the top 10 exporters (Evans and Mendoza 2009). Environmental conditions in southern Florida appear to be ideal for an increased importance of bacterial canker in the region as well as other areas in the Americas in which production of this crop occurs. (Resume d'auteur)

PM 7/128 (1) Xanthomonas axonopodis pv. allii

Specific scopeThis Standard describes a diagnostic protocol for Xanthomonas axonopodis pv. allii.This Standard should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.Specific approval and amendmentFirst approved in 2016‐09.

PM 7/60 (2) Pantoea stewartii subsp. stewartii

Specific scopeThis Standard describes a diagnostic protocol for Pantoea stewartii subsp. stewartii.Specific approval and amendmentApproved in 2005‐09.Revised in 2016‐04.

BACTERIAL WILT OF LIMA BEAN (PHASEOLUS LUNATUS) CAUSED BY CURTOBACTERIUM FLACCUMFACIENS PV. FLACCUMFACIENS, A NEW DISEASE IN IRAN

In the summer of 2013, during surveys in lima bean (Phaseolus lunatus) (cv. Christmas Pole) fields of East Azerbaijan, Northwest Iran, interveinal necrotic lesions and marginal chlorosis were observed on the leaves. The isolation of bacterial was done on Yeast Peptone Glucose Agar (YPGA) medium (EPPO, 2011). Yellow-colored colonies 1-2 mm in diameter were present on YPGA plates after incubation at 25°C for 48 h. All isolates were Gram-positive, of oxidative but not fermentative metabolism, and had the ability to grow at 37°C. All hydrolyzed aesculin, casein, and gelatin, produced acid from inositol, mannose and maltose but not from mannitol and erythritol, were of positive catalase and oxidase, but of negative urease and indole production (EPPO, 2011). Bacterial strains were identified as Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) based on biochemical test results. The pathovar-specific primer pair CffFOR2 and CffREV4 amplified a 306 bp fragment of the isolates and confirmed them as Cff (Tegli et al., 2002). The strains were deposited in the University of Tehran Microorganisms Collection (Accession No. Cffcb123). Pathogenicity test was conducted on 20 day old lima bean (cv. Christmas Pole) plants. The Cff suspensions (1×108 CFU/ml) were prepared from 48 h old culture on YPGA. Node infiltration method was conducted for the inoculation of plants (Hsieh et al., 2003). Disease symptoms appeared 10-15 days after inoculation. First trifoliate leaves of the inoculated plants exhibited symptoms of marginal necrosis and interveinal yellowing. Cff was consistently re-isolated from artificially infected lima bean tissues on YPGA and re-identified using CffFOR2 and CffREV4 primer pairs. This is the first report of Cff causing bacterial wilt in lima bean in Iran.

First report of potato bacterial ring rot caused by Clavibacter michiganensis subsp. sepedonicus in Africa

In 2014, potato tubers (cv. Diamant and cv. Spunta) showing typical symptoms of bacterial ring rot disease caused by Clavibacter michiganensis subsp. sepedonicus (Cms) were observed in Gharbia, Menoufia, Minia, Assiut and Sohag governorates, Egypt, in 10 out of 10,000 samples examined at the time of planting. Splitting infected tubers toward the stem end revealed a yellow to brown discolouration of the vascular tissue. The discoloured area had a cheesy appearance and exuded a milky ooze when squeezed (Fig. 1). Samples were tested for the presence of ring rot disease, according to the EC Directive 93/85/EEC (Anon., 1). Extracts from 1 cm tuber heel-end cores were streaked onto NCP-88 medium (de la Cruz et al., 2), yeast peptone glucose agar (Anon., 1) and yeast peptone glucose agar with the addition of neomycin (3.5 mg/l), polymyxin B sulphate (16250 IU) and clotrimazole (10 mg/l). The resultant colonies (white to cream, round to irregular with entire margins, raised, smooth, mucoid and glistening) were selected and purified. Suspensions of isolates in distilled water (106 cfu/ml) were injected (EU, 4) into stems of eight Solanum melongena plants (cv. Black Beauty) per isolate at the three leaf stage. Plants were incubated at 21 ± 2°C and 70-80% RH. Control plants were inoculated with sterile water. After 14 days plants began to wilt, wilted tissue appeared dark green or mottled but turned paler before becoming necrotic. Inter-veinal wilts had a greasy water-soaked appearance. Necrotic tissue had a bright yellow margin. Some plants were killed completely. No symptoms were observed in control plants. Bacteria were re-isolated from symptomatic inoculated plants and identified. Pure cultures of ten Gram-positive isolates hydrolysed aesculin, utilized acetate and produced catalase. They produced acid from mannitol and sorbitol, but not from glucose, glycerol, lactose and salicin. They were negative for oxidase activity, urease activity, hydrogen sulphide production, indole production, growth at 37°C, tolerance of 7% NaCl, and gelatin liquefaction. They gave negative or weak reactions for starch hydrolysis (Anon., 1). Identification of the isolates was confirmed by PCR using primers Cms50F/Cms50R (Gudmestad et al., 3) that yield an amplicon size of 192 bp. This is the first report of potato bacterial ring rot caused by Cms in Egypt. To our knowledge, this is the first report of Cms in Africa.

First Report of Xanthomonas arboricola pv. pruni in Ornamental Prunus laurocerasus in the Netherlands.

In 2008, Dutch ornamental plant growers observed a leaf spot of cherry laurel (Prunus laurocerasus) at a greater incidence (5 to 50%) than the usual sporadic level (<1%). For advice on disease control, ~5 to 10% of these growers contacted Dutch regulatory officials. In November and December 2008, six symptomatic samples from northern and southern parts of the Netherlands were submitted for diagnosis. Leaf spots were chlorotic, most had a necrotic brown center with a distinct margin, and the spots readily abscised, resulting in a "shot-hole" appearance. Leaf spots from the samples were surface sterilized (2 s in 70% vol/vol alcohol), blotted dry on tissue paper, chopped into pieces (1 to 2 mm in diameter), and incubated for 30 min in 10 mM phosphate-buffered saline (PBS) (1). A 20-μl aliquot of extract per sample was streaked by dilution plating on four plates of yeast peptone glucose agar medium (1), and the plates were incubated for 2 to 3 days at 28°C. Isolations from all six samples yielded Xanthomonas-like colonies. After purification, characterization of all six isolates revealed oxidative, nonfermentative metabolism of glucose by rod-shaped, gram-negative bacterial cells. All six isolates were identified as Xanthomonas arboricola pv. pruni based on biochemical tests (1), fatty acid analysis (4), and immunofluorescence (IF) using polyclonal antibodies (Plant Research International, the Netherlands). Pathogenicity was tested on potted peach plants (cvs. Peregrine and Vaes Oogst) and on detached leaves of P. laurocerasus (cv. Novita) (1). The six field isolates from 2008 were each inoculated (108 CFU/ml) onto four leaves per plant of each of two peach plants (replicates). As positive control treatments, two reference strains (ATCC 19312 and PD740) were each inoculated onto the same number of leaves and plants, and as a noninoculated negative control treatment, leaves of two peach plants were treated with sterile 10 mM PBS buffer (1). All leaves inoculated with the six field isolates and the two reference strains developed typical bacterial spot symptoms in 3 to 4 weeks. Negative control plants showed no symptoms. The detached leaf assay performed with the same treatments on each of two leaves (replicates) showed identical results. The bacterium was reisolated from leaf spots associated with each of the eight symptomatic treatments and identity of the reisolates was confirmed by IF. Additionally, genotypic variation of 35 Dutch isolates of X. arboricola pv. pruni was assessed by BOX-PCR assay with the BOX A1R primer set (3), and Gyrase B gene sequencing (2). Both methods revealed 100% homology among the 35 isolates, suggesting a single, recent introduction of X. arboricola pv. pruni into the Netherlands. In a 2009 survey to assess distribution of the disease in the Netherlands, X. arboricola pv. pruni was found in 41 fields. Infected hosts included P. laurocerasus cvs. Otto Luyken, Rotundifolia, Novita, Etna, Anbri, Herbergii, Mischeana, and Caucasia. X. arboricola pv. pruni is a quarantine organism in countries affiliated under the EPPO (European and Mediterranean Plant Protection Organization). Phytosanitary measures were taken to prevent movement of infested plants from nurseries where X. arboricola pv. pruni was detected.

Survival of Clavibacter michiganensis subsp. sepedonicus on surface of selected materials in different temperature conditionsPrzeżycie Clavibacter michiganensis subsp. sepedonicus na powierzchniach wybranych materiałów w warunkach różnych temperatur

Study were conducted at the Plant Breeding and Acclimatization Institute Research, Division Bydgoszcz in 2005−2007. The aim of this study was to determine a period of Clavibacter michiganenis subsp. sepedonicus (Cms) survival on storage surface of machinery, materials, and equipment contaminated by infected tubers with the bacteria during seeding operations, cultivation, harvest, storage and transport at different temperatures. BPR IOR 527 Cms strain was used. Six materials: wood, rubber, jute, plastic, paper, steel were contaminated with bacterial suspension at the concentration of 10 cfu/ml and put in Petri dishes and incubated at four temperatures. The survival of bacteria, by isolation on yeast peptone glucose agar (YPGA – Yeast peptone glucose agar) and virulence in eggplant test, periodically were controlled. The study confirmed that Cms can survive for lengthy period on different surface tested.

First Report of Xanthomonas axonopodis pv. poinsettiicola Causing Bacterial Leaf Spot of Euphorbia pulcherrima in Slovenia.

In September 2009, water-soaked spots, 2 mm in diameter, surrounded by a pale yellow halo were observed on leaves of pot-grown poinsettia plants (Euphorbia pulcherrima L.) cv. Christmas Feeling in a commercial greenhouse in Slovenia. Several spots per leaf developed on 10% of 84 plants used for propagation and slowly progressed to necrotic brown spots. While all plants were watered by overhead irrigation until mid-September, and afterward by flooding, no symptoms were observed on parent plants of four other separately grown cultivars. Propagated cuttings were all grown together, and in addition to cv. Christmas Feeling, an estimated 90% of 315, 35% of 29, 10% of 240, and 5% of 840 plants of cvs. Crazy Marble Star, Crazy Christmas, Lemon Snow, and Cortez Red, respectively, developed leaf spots. Yellow, smooth, and butyrous colonies with entire margins were isolated from symptomatic leaves of poinsettia parent plants of cv. Christmas Feeling on yeast peptone glucose agar (YPGA). They were identified as a Xanthomonas sp. based on biochemical tests (oxidase negative, positive for hydrolysis of H2S, starch and tributiryn and acid production from sucrose) and the isolates caused a hypersensitive reaction in leaves of tomato cv. Moneymaker. Partial sequences of gyrase subunit B-like (gyrB) gene (2) from an isolate (Accession No. HQ215596, 676 bp) showed highest similarity to Xanthomonas axonopodis pv. poinsettiicola strain LMG 5401 (Accession No. GU144264.1, 99% identity, 98% coverage) and 98% identity with gyrB sequence of X. axonopodis pv. poinsettiicola pathotype strain LMG 849 (Accession No. GU144273.1, 99% coverage, 3 gaps). Repetitive BOX-PCR (3) revealed high similarity of our isolate to pathotype strain LMG 849 with one additional band of approximate size of 1,500 bp present in our isolate. The pathogenicity of two isolates from parent plants of cv. Christmas Feeling was confirmed on four young poinsettia plants each. Plants were inoculated with a bacterial suspension of approximate concentration of 106 CFU/ml by spraying on the under side and upper side of the leaves, some of which were pricked with a sterile needle (1). Plants were then incubated under high relative air humidity (minimum 85%), 12 h of daylight, and 25°C day and 20°C night temperature regimens. After 10 days, all inoculated plants developed faint leaf spots, consistent with mild symptoms observed in the greenhouse. Colonies isolated from the developed spots had identical morphology and BOX-PCR profile to original isolates. Mock inoculated, negative control plants did not develop characteristic symptoms and no colonies similar to X. axonopodis pv. poinsettiicola were isolated from them. Bacteria isolated from leaf spots of other poinsettia cultivars had the same biochemical characteristics and BOX-PCR profiles as the first isolate. Since no leaf blight was observed on poinsettias in the greenhouse in the previous season and no host plants were kept between the seasons, imported parent plants are the most likely source of infection. To our knowledge, this is the first report of X. axonopodis pv. poinsettiicola on poinsettia in Slovenia, providing further data on the occurrence and potential economic damage of leaf blight of poinsettia in Europe.

Isolation and Identification of Bacteria Causing Tomato Leaf Spot in Yemen with Susceptibility of Certain Cultivars

This study was conducted to isolate and identify the causal agent of bacterial leaf spot disease on tomato in district fields in Kla’abah, Taiz, Yemen. Twenty isolates were obtained from tometoes leaves and fruit of infected plants. Yellow, raised and shiny colonies were developed on four media ((1% Glucose nutrient agar (GNA), Nutrient dextrose agar (NDA), Sucrose peptone agar (SPA) and Yeast peptone glucose agar (YPGA)). Pathogenicity test results showed three isolates were highly virulent while three other isolates were moderately virulent. The pathovar Xanthomonas campestris pv. vesicatoria was identified according to visible characteristics of the colonies by (GNA, NDA, SPA and YPGA) media, cell shape, and physiological and biochemical characteristics (ability to grow at 35o C, production of H2S and ability to assimilate certain carbohydrates). Results revealed the ability of Xanthomonas campestris pv. vesicatoria to infect nine tomato cultivars (Roma V.f., Riogrand Gala, Tomato Maryam, Gala, Riogrand, Local-G 1oo3, on gy.A Seed, Ti 2 ar and RioGrand-Tezier) causing leaf spot at 26 – 29o C. Results also showed on Ti 2 ar, Local-G 1oo3 and Roma V.f. cultivars a decreased level of bacteria multiplication while Riogrand Gala, on gy. A Seed and Riogrand cultivars showed increased bacteria population.

First Report of Xanthomonas cucurbitae Causing Bacterial Leaf Spot of Pumpkin on Réunion Island.

Bacterial leaf spot of cucurbits caused by Xanthomonas cucurbitae (3) can be of economic importance in tropical and subtropical production areas, most often within the Cucumis, Cucurbita, and Citrullus genera. The bacterium induces angular, water-soaked leaf spots, which sometimes turn necrotic with a chlorotic halo. Scab-like lesions on fruit may also be observed (1). During 2000, water-soaked, angular leaf lesions were collected from pumpkin (Cucurbita pepo) in a production field located at Petit Serré, Réunion Island. Yellow-pigmented Xanthomonas-like bacterial colonies were isolated on yeast peptone glucose agar. Amplified fragment length polymorphism analysis was performed on four pumpkin isolates together with reference strains of X. cucurbitae (LMG 690 [type strain] and LMG 8663) and the type strain of all other valid Xanthomonas species using SacI/MspI and four primer pairs (unlabeled MspI + 1 [A, C, T, or G] primers and 5'-labeled - SacI + C primer for the selective amplification step) (N. Ah-You, L. Gagnevin, P. A. D. Grimont, S. Brisse, X. Nesme, F. Chiroleu, L. Bui Thi Ngoc, E. Jouen, P. Lefeuvre, C. Verniére, and O. Pruvost, personal communication). The four isolates from pumpkin showed identical fingerprints and were most closely related to X. cucurbitae, with evolutionary genome divergences ≤0.05 (N. Ah-You et al., personal communication). One strain from diseased pumpkin (JW210-1) was further analyzed by multilocus sequence analysis using three housekeeping gene portions (atpD, dnaK, and gyrB) as described previously (N. Ah-You et al., personal communication). Although not fully identical, this strain displayed a similarity of >99% to the two reference strains of X. cucurbitae. Pumpkin and bottle-gourd (C. maxima), squash cv. aurore (C. pepo), cucumber cv. L-04 (Cucumis sativus), melon cv. cezanne (Cucumis melo), and watermelon cv. fou-nan (Citrullus lanatus) leaves were infiltrated (10 inoculation sites per leaf; three replicates) with bacterial suspensions prepared from strains JW210-1, LMG 690, and LMG 8663 and containing approximately 1 × 105 CFU ml-1. Negative controls consisted of leaves infiltrated with sterile tris buffer. Typical, water-soaked lesions that developed into necrotic spots were observed 6 to 8 days after inoculation for all inoculated plant species-strain combinations, but not for negative controls. One month after inoculation, mean Xanthomonas population sizes recovered from leaf lesions on KC semiselective medium (2) ranged from 1 × 107 to 1 × 108 CFU per lesion, typical of a compatible interaction. The reported outbreak was circumscribed to a single field and did not affect the local industry. No major outbreak of bacterial leaf spot of cucurbits has been reported on Réunion Island since 2000 on any host species of X. cucurbitae.

First Report in Mauritius of Bacterial Leaf Blight of Syngonium Caused by Xanthomonas campestris pv. syngonii

In November of 2006, necrotic leaf lesions with water-soaked margins were observed on Syngonium podophyllum in Floréal, Forest Side, and Réduit, Mauritius. Although not an economically important crop, the disease was of concern because syngonium is a host for Xanthomonas axonopodis pv. dieffenbachiae and the anthurium industry is of major economic importance in Mauritius. X. campestris pv. syngonii, described as the causal agent of bacterial leaf blight of syngonium (2), is genetically closely related to group 9.4 X. axonopodis pv. dieffenbachiae strains (3). In contrast to X. axonopodis pv. dieffenbachiae, X. campestris pv. syngonii strains are highly virulent on syngonium but are not pathogenic on anthurium or other Araceae, but both react similarly to the Xcd108 monoclonal antibody (Mab) (Agdia Inc., Elkhart, IN) and to a nested PCR assay designed for X. axonopodis pv. dieffenbachiae (4). X. axonopodis pv. dieffenbachiae and X. campestris pv. syngonii strains can be distinguished on the basis of restriction analysis of the amplicon of this PCR assay. Four pure cultures isolated from S. podophyllum were gram negative, yellow pigmented, and produced mucoid colonies on yeast peptone glucose agar (YPGA). One positive control strain of X. campestris pv. syngonii (LMG 9055 from the United States) and X. axonopodis pv. dieffenbachiae (LMG 695 from Brazil) were also used for all tests. All strains reacted positively with the Xcd108 MAb using indirect ELISA. DNA from all strains was amplified by the nested PCR assay, and the HincII restriction pattern of the amplicons identified strains from Mauritius as X. campestris pv. syngonii. Pathogenicity tests were performed on 8-month-old plants of Anthurium andreanum cv. Florida, Dieffenbachia maculata cv. Tropic Marianne, and S. podophyllum cv. Robusta by infiltrating suspensions containing ~1 × 105 CFU ml¯1 of each strain prepared from YPGA plates. Each strain was inoculated onto three young leaves (four inoculation sites per leaf) on two plants. Negative control plants received sterile Tris buffer solution (10 mM, pH 7.2). Plants were maintained in a growth chamber with day and night temperatures at 30 ± 1°C and 26 ± 1°C, respectively, 95 ± 5% relative humidity, 30 μmol·m¯2·s¯1 light intensity, and a photoperiod of 12 h (4). All strains caused typical water-soaked lesions 14 days after inoculation (dai) on syngonium. Lesions turned necrotic with chlorotic margins 27 to 34 dai. Typical bacterial blight lesions were observed on anthurium leaves inoculated with X. axonopodis pv. dieffenbachiae strain LMG 695, but no symptoms were observed 60 dai when strains from Mauritius and LMG 9055 were used. Amplified fragment length polymorphism analysis of four strains from Mauritius and additional reference, X. axonopodis pv. dieffenbachiae and X. campestris pv. syngonii strains, using SacI/MspI and four primer pairs (unlabeled MspI+1 [A, C, T, or G] primers and 5'-labeled-SacI+C primer for the selective amplification step) (1), showed that the strains from Mauritius could be distinguished from X. axonopodis pv. dieffenbachiae but were identical to X. campestris pv. syngonii strains from the United States and Réunion Island.

Pseudomonas corrugata: plant pathogen and/or biological resource?

SUMMARY Pseudomonas corrugata is the causal agent of tomato pith necrosis yet it is also used in the biological control of plant pathogenic bacteria and fungi. Potentially it could be used in other fields, such as the production of commercial biomolecules with a wide range of application and including bioremediation. This review reports the multiple characteristics of the bacterium, highlights its known molecular features and speculates on the possible underlying mechanisms of action. Bacteria; Proteobacteria; gamma subdivision; order Pseudomonadales; family Pseudomonadaceae; genus Pseudomonas. Microbiological properties: Gram-negative, oxidase-positive, non-spore forming rods; non-fluorescent on King's B medium; produces wrinkled and rarely smooth colonies on yeast peptone glucose agar or nutrient dextrose agar; yellow to brown diffusible pigments are frequently produced. Disease symptoms: The typical symptom on tomato is necrosis and/or hollowing of the pith of the stem; the syndrome determines loss of turgidity of the plant, hydropic/necrotic areas and long conspicuous adventitious roots on the stem. Biological control agent: In vitro assessed against plant pathogenic fungi and bacteria, as well as the phytotoxin indicator microorganims Rhodotorula pilimanae and Bacillus megaterium; in vivo used against pre- and post-harvest plant pathogens.

Clavibacter michiganensis subsp. michiganensis

<i>Clavibacter michiganensis</i> subsp. <i>michiganensis</i>