رديابي عوامل باكتريايي سوختگي برگي لوبيا در استان هاي لرستان، مركزي و همدان

چكيده انگليسي :

125 Detection of Bacterial Causal Agents of Bean Leaf Blight in Lorestan Markazi and Hamedan Provinces Mohammad ghobadi alami M ghobadi36@gmail com January 4 2015 Department of Plant Protection Isfahan University of Technology Isfahan 84156 83111Degree M Sc Language FarsiSupervisor M bahar mbahar@cc iut ac irAbstractBean Phaseolus vulgaris L with regard to large caloric intake and protein contents ranks next in importance to cereals and potato The majorbacterial diseases including common bacterial blight Xanthomonasaxonopodis pv phaseoli halo blight Pseudomonassavastonoi pv phaseolicola and bacterial wilt Curtobacteriumflaccumfaciens pv flaccufmaciens are three commonly occurring bean diseases worldwidewhich have the potential to causesignificantyield losses through foliage blight and wilting disorders In recent years rapidly spreadingoutbreaksof foliage blight and wilting has been developed in bean fields of Iran although their causative agents have not been clearly determined Toinvestigate the causal pathogens of bean blight and wilting a survey was conducted in bean fields of Lorestan Hamedan and Markazi provincesduring 2013 2014 Of the samples collected from commercial fields located in these regions total of 57 bacterial isolates were recovered ongeneral and semiselective media According to their morphological serological and molecular characteristics the isolates were categorized intothree distinct groups The Bacterial strains in group I were Gram negative with translucent yellow colonies which are identified asXanthomonasaxonopodispv phaseoli Xap based on biochemical and serological properties The isolates also produced a 730bp DNA fragmentin PCR reaction using specific primer pair X4c F X4e R for Xap The bacterial strains in group I was not able to diffuse melanin pigment inthe culture and failed to amplify a DNA fragment with specific primer pair Xf1 Xf2 for Xanthomonasfuscans subsp fuscans confirming theidentification of strains group I as Xap The Gram positive bacterial representatives in group II formed creamy yellow colonies on Nutrient Agarmedium and produced a 306 bp DNA band in PCR reaction using specific primer pair Cff For2 Cff Rev4 for Curtobacteriumflaccumfacienspv flaccufmaciens Cff The biochemical test also support the findings that the isolates group II belonged to Cff The most isolates of Cff wereappeared yellowish carotenoid pigments and pink on Nutrient Broth Yeast NBY medium All the strains classified in group III producedfluorescent colonies on King s B medium This together with amplification of a fragment of approximately 1000 bp of the 16SrDNA gene withPseudomonas genus specific primer pair Ps for Ps rev allowed the identification of the strains group III as Pseudomonas sp However themajority of isolates in group III were found non pathogenic on bean plants and therefore no further biochemical tests were carried out for theirspeciation Of the isolates group III one pathogenic strain was identified as Pseudomonas viridiflava based on its biochemical characteristic Partial amplification and sequence analysis of the 16S rDNA of this isolate with primer Ps For Ps Rev also revealed that the strain is identicalto P viridiflava After confirming the presence of Cff and Xap as the main causal agents of bean foliage blight and wilting a multiplex PCR wasperformed using X4c F X4e R and Cff primers for the simultaneous detection of Xap and Cff bacteria in the infected leaf and seed materials Inall the samples subjected to multiplex assay a 306 bp band specific for Cff observed along with a 730bp band specific for Xap The dataobtained in the present study reveals the occurrence of both foliage blight and wilting diseases in bean fields of Lorestan Hamedan and Markaziprovinces caused by Xap and Cff respectively Since both of the pathogens are transmitted by seed lots multiplex PCR assay could be a reliableand sensitive method for determining whether or not seeds are infected with these pathogens Key words B

قبادي علمي، محمد

رديابي عوامل باكتريايي سوختگي برگي لوبيا در استان هاي لرستان، مركزي و همدان

واريانت صورتي , واريانت زرد , حساسيت PCR , Multiplex PCR