مقايسه رفتارهاي بيولوژيكي و مولكولي بيووارهاي ايراني 2Aو 2T باكتري Ralstonia solanacearum

چكيده انگليسي :

Abstract Potato bacterial wilt caused by Ralstonia solanacearum is one of the predominant diseasesencountered worldwide It has been determined that both biovars 2A and 2T race 3 of R solanacearum is the causal agent of bacterial wilt in Iran Despite distribution of Biovar 2A in mainpotato growing areas Biovar 2T is limited to Khuzestan province with warm climate Therefore abetter characterization of their ecological and pathological behaviors would facilitate to managetheir control For this purpose 15 Iranian strains of biovar 2 race 3 of R solanacearum consisted ofeight biovar 2A isolated from Isfahan and 7 biovar 2T isolated from Khuzestan were subjected tocompare in detail for morphological molecular biochemical characteristics and pathogenicitycircumstances under different climatic conditions All strains of biovar 2A were developed in TZCmedium with irregular highly fluidal creamy white with pink center colonies and producedmelanin pigments in the culture while colonies of strains 2T were small less fluidal round shaped containing deep red color with a thin white margin without melanin production The strainsconformed closely to the established set of biochemical and physiological tests for biotype 2 of R solanacearum Strains belong to biovar 2T utilized ribose and tryptophane while 2A strains did notuse these compounds In PCR reactions with specific primers sets PS759f 760r and RS1F R all ofthe strains yielded characteristic products PCR RFLP analysis of these products with AluI RsaIand TaqI endonucleases resulted fragments with similar sizes among the strains supporting furthertheir identity as R solanacearum Comparative analysis of the strains based on BOX IR and ERIC PCR fingerprinting separated strains biovar 2A and biovars 2T into two distinct subgroups whichwas compatible with their morphological and biochemical characterization results Infiltration ofbacterial suspensions of biovar 2T strains in tobacco leaves induced a rapid localized necroticresponse within 24 to 48 h characteristic of the hypersensitive response HR while strains biovar2A elicited a yellowish discoloration and weaker necrosis at the same time To evaluate thepathogenicity of strains two isolates representing biovars 2A and 2T were inoculated in six potatocultivars Agria Arinda Marfona Labida Ramus and Sante tomato eggplant and petunia plantsat the third internode from the apex After inoculation the pots were arranged in a randomizedcomplete design and then potato plants placed in two different cold 31 25 C and warm 39 45 C greenhouse conditions The aggressiveness of strains was evaluated by appearance of wiltingsymptoms and estimating of bacterial density in the xylems of inoculated plants over a four weeksperiod Significant differences in aggressiveness among biovar 2A and 2T was detected inexperiments Isolates representing biovar 2T caused less disease in all the species and cultivarscompared to isolates biovar 2A at both temperature regimes The ranking of bacterial density ofinoculated plants xylems was generally positively correlated with the ranking of wilting symptoms The pathogenicity experiment indicated that the potato cultivars were significantly different fromeach other in susceptibility to biovars 2A and 2T of R solanacearum The potato cultivars testedwere susceptible to biovars of R solanacearum but there was a large variation in the level ofsusceptibility Based on disease index results cv Sante was found reasonably tolerant to bothbiovars of R solanacearum in different cool and warm conditions whereas cv Ramus and cv Labida were highly susceptible Among the reminder cultivars cv Marfona was moderatelytolerant but Agria and Arinda were determined almost sucesptible To determine survival of biovars2A and 2T in soil suspention of the strains was inoculated in soil with controlled humidity invitro The recovery of bacteria from each soil sample was carried out by PCR using species specificprimers and culture medium periodically It was fou

حسبي، حميده

مقايسه رفتارهاي بيولوژيكي و مولكولي بيووارهاي ايراني 2Aو 2T باكتري Ralstonia solanacearum

سيب زميني , استان خوزستان , راموس , لابيدا , مارفونا , آگريا , آرنيدا , سانته