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چکیده
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Sugar beet like other plants harbors the vast number of bacteria on the surface. Generally, plant-associated bacteria are divided into three main types: endophytic, epiphytic, and rhizobacteria. To determine sugar beet bacterial pattern, 23 sugar beet plants were selected from 12 major growing sites in the west of Iran during the growing season of 2013. Total of 452 strains were isolated from sugar beet of which, 217 strains belonged to rhizosphere, 70 to leaf epiphytic, 85 to leaf endophytic types, and 80 strains to the seed. To select the representative strains, whole cell proteins were extracted and electrophoresed based on Laemllei method. We determined 54 protein fingerprints which among, eight electrotypes were the major occurring. Thus, one representative strain from each electrotype was selected and its morphological features characterized according to the standard bacteriological criteria. The 16S rRNA encoding gene from these representatives was amplified using fD1 and rD1 universal primers, subjected to sequencing and aligned in the NCBI. Consequently, five species were detected to be dominant in the rhizosphere and identified as S. maltophilia, P. fluorescens, S. rhizophila, P. aeruginosa, and S. marscens with the frequency of 14, 14, 12, 11 and 10 percent respectively. Seed-associated bacteria were identified as S. maltophilia as the endophytic and P. geniculata and S. rhizophila as epiphytic types. Three electrotypes were dominant in leaf endophyte and identified as Aceinetobacter colcoaceticus, S. maltophilia, and P. aeruginosa with the frequency of 42, 20 and 15 percent, respectively. Two leaf epiphytic major electrotypes were identified as B. simplex and S. marcesens with the frequency of 48 and 25 percent respectively. Molecular fingerprints using Eric and Box primers showed the highest genetic variation among P. fluorescens and S. maltophilia strains. Conversely, Acinetobacter calcoaceticus showed the least genetic variation. Our investigation sho
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