Isolation of Agrobacterium tumefaciens Strains from

Cultivar of roses (Rosa spp.) has been grown in greenhouses in Qazvin region of Iran for local markets. Agrobacterium tumefaciens strains were identified and isolated from six different samples of roses plants imported from the Netherlands to Iran. During August and September of 2012, nearly 2- 5% of rose plants in two different greenhouses in the province of Qazvin were observed with crown gall symptoms on various parts, particularly in the stem. A non-fluorescent gram-negative bacterium was consistently isolated from diseased tissues onto Kingʹs B medium. The isolated strains were confirmed as Agrobacterium using different biochemical and pathogenicity (tumor forming ability) tests. Four representative strains isolated were aerobic, non-sporing, non-pigmented, motile, rod-shaped, oxidase negative and catalase positive. All of four isolates (AtRA1, AtRA2, AtRQ1 and AtRQ2) were positive for tumor forming ability for pathogenicity tests on Carrot Disc and Tomato stem.