پزشکان گیاهان

بحث علمی

plantago — Tue, 08 Dec 2009 11:35:46 GMT

دوستان خواننده نظرات خود را در مورد پدیده فوق حساسیت و علت وقوع آن اعلام کنید( با ذکر منبع) تا برای استفاده جمعی منتشر گردد.

انجمن بیماری شناسی کشور ها

plantago — Tue, 24 Nov 2009 08:50:18 GMT

Argentina	Argentine Crop Protection Society
Australasia	Australasian Plant Pathology Society
Belgium	Belgium Association for Research in Zoology and Phytopathology
Brazil	Brazilian Society of Plant Pathology
Canada	Canadian Phytopathological Society
China	Chinese Society for Plant Pathology China Taiwan Phytopathological Society
Colombia	Asociación Colombiana de Fitopatología y Ciencias Afines
Denmark	Danish Society for Plant Pathology
Egypt	Egyptian Phytopathological Society
Ethiopia	Ethiopian Society of Plant Pathology
Finland	Plant Protection Society of Finland
France	Société Française de Phytopathologie
Germany	German Phytomedical Society
Greece	Hellenic Phytopathological Society
Hungary	Hungarian Society of Plant Protection
India	Indian Phytopathological Society
Indonesia	Indonesian Phytopathological Society
Iran	Iranian Phytopathological Society
Ireland	Society of Irish Plant Pathologists
Israel	Israeli Phytopathological Society
Italy	Italian Phytopathological Society Mediterranean Phytopathological Union Italian Association for Plant Protection
Japan	The Phytopathological Society of Japan
Kenya	Plant Pathology Society of Kenya
Korea	Korean Society of Plant Pathology
Mexico	Society Mexicana Fitopatologia
Morocco	Association National pour la Production, la Protection, et l'Amelioration Vegetale
Netherlands	Royal Netherlands Society of Plant Pathology
New Zealand	Australasian Plant Pathology Society
Nigeria	Nigerian Society of Plant Protection
Norway	Norwegian Society of Plant Pathology
Pakistan	Pakistan Phytopathological Society
Peru	Asociacon Peruana de Fitopatologia
Philippines	Philippine Phytopathological Society
Poland	Polish Phytopathological Society
Portugal	Portuguese Phytopathological Society
Russia	Russian Phytopathological Society
Spain	Society Espanola de Fitopatologia
Sudan	Sudanese Society of Plant Pathology
South Africa	Southern African Society for Plant Pathology
Sweden	Swedish Society of Biopathology
Switzerland	Schweizerische Gesellschaft für Phytomedizin
Thailand	Thai Phytopathological Society
UK	Association of Applied Biologists British Mycological Society British Society for Plant Pathology
USA	American Phytopathological Society
Regional Societies:	Arab Society for Plant Protection Asociacon Latinoamericana de Fitopatologia Australasian Plant Pathology Society European Foundation for Plant Pathology Italian Association for Plant Protection Mediterranean Phytopathological Union Quebec Society for the Protection of Plants Southern African Society for Plant Pathology

leaf spot on cowpea (Vigna unguiculata) caused by Xanthomonas axonopodis pv. vignicola in Mozambique

plantago — Fri, 20 Nov 2009 16:09:04 GMT

C. Moretti¹, A.M. Mondjana², A. Zazzerini¹ and R. Buonaurio^1*

¹Dipartimento Scienze Agrarie e Ambientali, Sezione di Arboricoltura e Protezione delle Piante, UniversitÃ degli Studi di Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy
² Faculdade de Agronomia, Universidade de Eduardo Mondane, Maputo, Mozambique

*buonaurio@unipg.it

Accepted for publication 21 Jun 2006

In June 2004, angular, necrotic, pustuliform leaf spots, surrounded by a thin water-soaked halo, were observed on cowpea (Vigna unguiculata) plants (Fig. 1), cultivated in the Umbeluzi area (Maputo, Mozambique), with an incidence of 70-90%.

Yellow, circular and raised bacterial colonies were consistently isolated on nutrient agar from diseased leaves. Six selected representative bacterial strains and the reference strain LMG 8752 of Xanthomonas axonopodis pv. vignicola were subjected to identification tests. All strains were gram negative, had oxidative but not fermentative metabolism and a mucoid growth on yeast dextrose chalk agar. All hydrolysed esculin and casein, produced acid from arabinose, and hydrogen sulphide from cysteine. When the first trifoliate leaves of 3-week-old cowpea plants (four plants for each strain) were infiltrated with 10⁶ CFU per ml bacterial suspensions, small water-soaked spots started to appear 6-7 days after inoculation. Bacteria were re-isolated from inoculated plants and found to be identical to the bacterial isolates used for inoculation. With the primers used for Xanthomonad identification in PCR analysis (Leite et al., 1994), RST2/RST3 generated a 840 bp amplification product from all bacterial strains, whereas RST9/RST10 produced no amplification products. Furthermore primers X4c-X4e, specific for the detection of the cowpea pathogen X. axonopodis pv. phaseoli (Audy et al., 1994), did not generate any amplification products. On the basis of these results we can conclude that the bacterial strains isolated from cowpea plants belong to X. axonopodis pv. vignicola. Characterisation of the bacterial strains carried out using the Biolog system demonstrated that our bacterial strains grew on the 19 substrates used by all the 55 X. axonopodis pv. vignicola strains characterised by Khatri-Chhetri et al. (2003). However, we found metabolic profiles different from those observed by these authors, when 10 variably used carbon sources were considered (results not shown). While X. axonopodis pv. vignicola strains from Mozambique have been characterised by Khatri-Chhetri et al. (2003), this is the first definitive report of the disease cowpea leaf spot caused by Xanthomonas axonopodis pv. vignicola in this country.

Figure 1: Angular, water-soaked and necrotic spots caused by Xanthomonas axonopodis pv. vignicola on cowpea leaf

References

Audy P, Laroche A, Saindon G, Huang HC, Gilbertson RL, 1994. Detection of the bean common blight bacteria, Xanthomonas campestris pv. phaseoli and Xanthomonas campestris pv. phaseoli var. fuscans, using polymerase chain reaction. Phytopathology 84, 1185-1192.

Khatri-Chhetri GB, Wydra K, Rudolph K, 2003. Metabolic diversity of Xanthomonas axonopodis pv. vignicola, casual agent of cowpea bacterial blight and pustule. European Journal of Plant Pathology 109, 851-860.

Leite RPJ, Minsavage GV, Bonas U, Stall RE, 1994. Detection and identification of phytopathogenic Xanthomonas strains by amplification of DNA sequences related to the hrp genes of Xanthomonas campestris pv. vesicatoria. Applied and Environmental Microbiology 60, 1068-1077. The British Society for Plant Pathology

First report of bacterial leaf spot disease, caused by Xanthomonas axonopodis pv. begoniae, on begon

plantago — Fri, 20 Nov 2009 16:01:26 GMT

H. Ornek¹, Y. Aysan^1*, M. Mirik² and F. Sahin³

¹ Department of Plant Protection, Faculty of Agriculture, Cukurova University, TR-01330 Adana, Turkey² Department of Plant Protection, Faculty of Agriculture, Trakya University, TR-59030 Tekirdag, Turkey³ Yeditepe University, Faculty of Engineering and Architecture, Department of Genetics and Bioengineering, TR-34755 Istanbul, Turkey

*aysanys@cu.edu.tr

Accepted for publication 29 Jun 2006

In the spring of both 2003 and 2004, serious outbreaks of a suspected bacterial leaf spot disease were observed on tuberous non-stop begonia plants (Begonia x tuberhybrida cvs. Futta, Kleo, Apricot and Red) and strawberry begonia (Saxifraga sarmentosa) grown for potted production in commercial greenhouses located in Adana, Manisa, Yalova and Istanbul provinces of Turkey. The initial symptoms of the disease were small round spots and angular necrotic areas on leaf surfaces (Fig. 1). A general leaf yellowing and necrosis followed the spotting. Defoliation, open stem canker and vascular discoloration were observed on plants in advanced stages of the disease (Fig. 2).

Disease incidence was recorded in the range of 15-30% over two years. Isolations were made from leaves and stems of the affected plants on YDC agar.Bacteria consistently isolated from the diseased tissues formed yellow-coloured mucoid and convex colonies on the media. Eighteen bacterial strains were purified and used for further studies. All isolate were characterised as non-sporing, gram negative, rod-shaped, motile, aerobic, oxidase-negative, catalase-positive and amylolytic-positive (Schaad et al., 2001). All of the bacterial strains isolated in the present study were identified as Xanthomonas axonopodis pv. begoniae (Xab; Vauterin et al., 1995) based on fatty acid methyl ester analysis (Yeditepe University, Istanbul, Turkey) with similarity indices ranging from 51 to 77 % (Chase et al., 1992) and indirect-ELISA tests (Agdia BRA 23700) (Benedict et al., 1990). All of the test results were similar to those of the reference strain used in this study.

Pathogenicity was confirmed by spray inoculation of the leaves on tuberous begonia and strawberry begonia plants. Sterile distilled water and a reference strain (BPIC 2013, Xanthomonas axonopodis pv. begoniae) were used as negative and positive controls respectively. All plants were covered with polyethylene bags for 48 hour at 25^oC. After inoculation, water-soak and necrotic symptoms were observed on tuberous and strawberry begonia plants within 5-7 days (Fig. 3-4). No symptoms were observed on control plants. This is the first report of Xab in commercial floriculture in Turkey and to the best of our knowledge is also the first report of infection of strawberry begonia by this pathogen anywhere.

Figure 1: Angular necrotic areas caused by Xanthomonas axonopodis pv. begoniae on (left) tuberous begonia leaves and (right) strawberry begonia leaves

Figure 2: Necrosis and ooze on stems of tuberous begonia caused by Xanthomonas axonopodis pv. begoniae

Figure 3: Leaf spot symptoms on Begonia x tuberhybrida after inoculation.

Figure 4: Leaf spot symptoms on Saxifraga sarmentosa after inoculation.

Acknowledgements

The research was supported by a grand from Cukurova University of Turkey with a project numbers ZF2005YL48 and ZF2005BAP9. The reference bacterial strain, BPIC 2013, Xanthomonas axonopodis pv. begoniae, were kindly provided by Dr A.S. Alivizatos, Benaki Phytopathological Institute, Kifissia, Greece.

References

Benedict AA, Alvarez AM, Pollard LW, 1990. Pathovar specific antigens of Xanthomonas campestris pv. begoniae and X. campestris pv. pelargonii detected with monoclonal antibodies. Applied and Environmental Microbiology 56, 572-574.

Chase AR, Stall RE, Hodge NC, Jones JB, 1992. Characterization of Xanthomonas campestris strains from Aroids using physiological, pathological, and fatty acid analysis. Phytopathology 82, 754-759.

Schaad NW, Jones JB, Lacy GH, 2001. Xanthomonas. In: Laboratory guide for identification of plant pathogenic bacteria. Third Edition (Eds. Schaad, N.W., Jones, J.B., Chun, W.). APS Press, St. Paul Minnesota.

Vauterin L, Hoste B, Kersters K, Swings J, 1995. The relationship within genus Xanthomonas and a proposal for a new classification. International Journal of Systematic Bacteriology 45: 472-489.

plantago — Wed, 18 Nov 2009 09:32:30 GMT

Professor T, Cavalier-Smith FRS
Professor of Evolutionary Biology

درخت اوجا Ulmus minor

plantago — Sun, 15 Nov 2009 13:26:42 GMT

باکتری بیماریزا در گوجه فرنگی در خراسان رضوی

plantago — Wed, 11 Nov 2009 19:24:39 GMT

اسفندیار ظهور

گوجه فرنگي (Lycopersicon eseulentum Mill) ميزبان تعداد باكتري بيماريزاي گياهي مي باشد پژمردگي باكتريايي گوجه فرنگي ناشي از Ralstonia solanacearum (Rs) درسال1372 از فارس ، بيماري خال زدگي باكتريايي گوجه فرنگي ناشي از Pseudomonas syringae pv tomato (Pss) در سال1373 از ورامين وشانكر باكتريايي گوجه فرنگي Clavibacter michiganensis ssp. michiganensis(Cmm) در سال 1367 در حومه اروميه ديده شد.علايم بيماري در Pst بصورت لكه هاي گرد و نامنظم تا قهوه اي و سياه با كلروز گسترده و يا محدود روي برگها و لكه هاي بيضوي كشيده روي دمبرگ، كاسبرگ ، دمگل و شاخه وساقه ودر روي ميوه بصورت خالهاي سياه پراكنده سطحي وگاه با هاله كلروتيك روي ميوه رسيده است .در حالي كه در شانكر باكتريايي گوجه فرنگي علائم بيماري شامل پژمردگي بوته بروز شانكر هاي قهو ه اي روي ساقه و دمبرگ ، تيره شدن بافت آوندي و بعضي موارد ظهور لكه هاي مدور سفيد با برجستگي كوچك قهوه اي در مركز آن بر روي پوست ميوه مي باشد. در پژمردگي باكتريايي گوجه فرنگي علايم بيماري عبارت است. از پژمردگي و پلاسيدگي برگها سبز خشكي سريع شاخ و برگ و تغيير رنگ سيستم آوندي ساقه است. علائم پوسيدگي نرم درساقه گياهچه و بوته ها و ميوه هاي گوجه فرنگي در اثر اين دو عاملPectobacterium carotovorum subsp. carotovorum(Pcc) وDickeya chrysanthemi(Dc) ميباشد. طي سالهاي 1385 تا 1387 تعدادي نمونه از بوته هاي آلوده گوجه فرنگي جمع آوري و به روش هاي معمول باكتري شناسي مورد بررسي قرار گرفت نتايج حاصل از اين بررسي به منزله عدم وجود بيماري Cmm در مزارع خراسان رضوي و احتمال وجود پاتواري از Ps بر روي مزارع گوجه فرنگي و وجود باكتري اپي فيت Pantanoe herbicola مي باشد. علائم پوسيدگي نرم در ساقه و گياهچه بوته هاي گوجه فرنگي در اثر عامل Pc نيز مشاهده شد.

Occurrence of Pseudomonas mediterranea on tomato in Brazil

plantago — Tue, 10 Nov 2009 11:27:55 GMT

L.M.R. Rodrigues¹, S.A.L. Destéfano², L.O.S. Beriam² and J. Rodrigues-Neto²*

¹Departamento de Proteção de Plantas, UNESP, 18.603-970, Botucatu, SãoPaulo, Brazil
²Laboratório do Bacteriologia Vegetal, Instituto Biológico, PO Box 70, 13.106-970, Campinas, São Paulo, Brazil

*julio@biologico.sp.gov.br

Accepted for publication 10 Sep 2009

During the years 2005-2008, symptoms of tomato pith necrosis (TPN) were observed that caused significant losses in several commercial cropsin the State of São Paulo, Brazil. Symptoms were similar to those reported for Pseudomonas corrugata or P. mediteranea and often first appeared near wounds where side-shoots had been removed, causing external dark brown necrosis of stems and degradation of pith (Fig. 1). Isolations from diseased plants on King’s medium B resulted in the growth of a bacterium with smooth or wrinkled colonies producing a greenish-yellow, non-fluorescent, diffusible pigment. Isolates were tested for pathogenicity on young tomato plants by placing a drop of bacterial suspension (10⁸cfu/ ml) in the leaf axils and then pricking the stem with a sterile needle. Control plants were similarly treated using sterile distilled water. Plants were maintained in a glasshouse with temperatures ranging from 25 to 30º C. The type strains of Pseudomonas corrugata (IBSBF 647^T) and P. mediterranea (IBSBF 2059^T) were used for comparative purposes.

The pathogenicity of isolateswas confirmed two weeks after inoculation (Fig. 2). The bacteria were aerobic, positive for oxidase, arginine dihydrolase, nitrate reduction to nitrites, meso-tartrate and histamine utilization, and negative for levan production and aesculin hydrolysis. In rep-PCR using BOX primers, the isolates showed identical profiles to those of the type strain of P. mediterranea (Fig. 3). In PCR using the primers type I ( PC5/1 and PC5/2) for P. corrugata and type II (PC1/1 and PC1/2) for P. mediterranea (Catara et al., 2002) the identities of strains were confirmed by the amplification of a 600 bp DNA fragment specific to P. mediterranea (Fig. 4). Until now, only P. corrugata had been reported as causing TPN in Brazil (Martins et al., 1990; Rodrigues-Neto et al., 1990). Consequently, this is the first report of P. mediterranea causing TPN in Brazil.

Figure 1: External symptoms of pith necrosis caused by Pseudomonas mediterranea on tomato stem

Figure 2: Pith discoloration in a tomato stem after artificial inoculation with a Brazilian isolate of Pseudomonas mediterranea

Figure 3: BOX-PCR fingerprinting patterns of Pseudomonas corrugata and Pseudomonas mediterranea; (M) 100 bp DNA marker, (1) Pseudomonas corrugata type strain (IBSBF 647T) , (2) Pseudomonas mediterranea type strain (IBSBF 2059T), (3-6) Pseudomonas mediterranea isolates from Brazil (IBSBF 1903, IBSBF 2642, IBSBF 2643, IBSBF 2652)

Figure 4: PCR amplification of 1100 bp and 600 bp DNA fragment of (1) Pseudomonas corrugata type strain (IBSBF 647T) , (2) Pseudomonas mediterranea type strain (IBSBF 2059T), (3-7) Pseudomonas mediterranea isolates from Brazil (IBSBF 1903, IBSBF 2642, IBSBF 2643, IBSBF 2652, IBSBF 2654), (M) 100 bp DNA marker

References

Catara V, Sutra L, Morineau A, Achouak W, Christen R, Gardan L, 2002. Phenotypic and genomic evidence for the revision of Pseudomonas corrugata and proposal of Pseudomonas mediterranea sp. nov. International Journal ofSystematic andEvolutionary Microbiology 52, 1749-1758.

Martins OM, Couto ME, Patella AEC, 1990. Occurrence of Pseudomonas corrugata on tomato in Rio Grande do Sul, Brazil. (Abstract from Congress of the Brazilian Phytopathololgical Society.) Fitopatologia Brasileira 15, 125.

Rodrigues-Neto J, Malavolta Jr VA, Ramos RS, Sinigaglia C, 1990. Ocorrência de Pseudomonas corrugata em tomateiro no Estado de São Paulo. Summa Phytopathologica 16, 279-284.

Acidovorax avenae subsp. citrulli newly reported to cause bacterial fruit blotch of watermelon in Gr

plantago — Tue, 10 Nov 2009 11:23:13 GMT

M.C. Holeva*, C.D. Karafla, P.E. Glynos and A.S. Alivizatos

Benaki Phytopathological Institute, 8 S. Delta Str. GR-145 61 Kifissia, Attiki, Greece

*m.holeva@bpi.gr

Accepted for publication 06 Oct 2009

In July 2005 and September 2006, samples of mature fruits of F1 hybrid watermelon (Citrullus lanatus) cv. Obla were received from the areas of Chryssoupoli (Macedonia, northern Greece) and Vagia (central Greece), respectively. Fruits had small, irregular, water-soaked lesions and brown cracks on their surface, brown discolouration and water-soaked areas in the rind underneath the lesions, and watery flesh rot (Figs. 1, 2). Disease incidence was reported as severe in both areas, according to the sample information sheets sent by local agronomists. Bacterial isolates recovered on nutrient agar (NA) from the affected fruits were Gram-negative, oxidase positive, non-fluorescent on King’s medium B, pathogenic to inoculated watermelon fruits and to seedlings of watermelon, melon, cucumber and pumpkin; isolates induced tobacco hypersensitivity and formed characteristic white colonies on nutrient agar. Based on these data, the isolates were identified as Acidovorax avenae subsp. citrulli (Aac).

In May 2008, young grafted watermelon plants (F1 hybrid cv. Byblos) received from the area of Varda (Peloponnese, southern Greece) showed brown, angular, necrotic spots or larger lesions on leaves (Figs. 3, 4). This outbreak was reported by the agronomist in charge of the crop to have affected about 50% of a plot of 12,000 plants. The bacterial isolates recovered on NA from the affected plants showed the above properties and also growth at 41°C, no starch hydrolysis, oxidative glucose metabolism and utilisation of D-galactose, D-glucose, L-arabinose, but not adonitol, arginine or sucrose, as sole carbon source. An immunofluorescence test with Aac-specific polyclonal antiserum (LOEWE, Germany) and sequencing (COGENICS, UK)of the products of PCR with two sets of Aac-specific primers, viz. BX-L1F/BX-R5F and BX-L1F/BX-S-R2R (Bahar et al., 2008), or the set 63f/1389r (Osborn et al., 2000) amplifying part of the 16S rDNA region, verified the isolates as Aac.In Rep-, Eric- or Box-PCR, the isolates from plants and Aac reference strains produced similar banding patterns. Koch’s postulates were fulfilled on seedlings and fruits of the above mentioned cucurbits with all isolates from plants. One such isolate was deposited in the Benaki Phytopathological Institute Culture Collection as BPIC2124. This is the first report confirming Aac naturally infecting watermelon plants and fruits in Greece.

Figure 1: Watermelon fruit naturally infected by Acidovorax avenae subsp. citrulli, showing irregular, water-soaked lesions and brown cracks on the surface

Figure 2: Section of watermelon fruit naturally infected by Acidovorax avenae subsp. citrulli, showing water-soaked areas in the rind underneath the surface lesions and watery rot of the flesh.

Figure 3: Young grafted watermelon plant naturally infected by Acidovorax avenae subsp. citrulli

Figure 4: Leaf of a young grafted watermelon plant naturally infected by Acidovorax avenae subsp. citrulli, showing symptoms of brown, angular, necrotic spots and larger necrotic areas

Acknowledgements

The authors wish to thank Dr S. Burdman for providing the Aac reference strains: W1, M1 (Bahar et al., 2008).

References

Bahar O, Efrat M, Hadar E, Dutta B, Walcott RR, Burdman S, 2008. New subspecies-specific polymerase chain reaction-based assay for the detection of Acidovorax avenae subsp. citrulli. Plant Pathology 57, 754-763.

Osborn AM, Moore ERB, Timmis KN, 2000. An evaluation of terminal-restriction fragment length polymorphism (T-RFLP) analysis for the study of microbial community structure and dynamics. Environmental Microbiology 2, 39-50