Isolation and identification of Agrobacterium tumefaciens from the galls of peach tree

Peach (Prunus perisca) is a very important fruit and it is attractive all over the world due to its delicious aroma and flavor. Peach is susceptible to various types of pathogens that result in decline of its fruit production. An important pathogen, Agrobacterium tumefaciens attacks on peach plant and it causes crown gall disease. The present study was conducted to identify the peach plants infected with Agrobacterium tumefaciens and isolate as well as identify the bacterium from the crown gall samples. These samples were collected from different locations including district Swat and Shangla. The bacterium was isolated from the samples using MacConkey selection media that is used specifically for identification of Agrobacterium tumefaciens. Two different biochemical tests i.e. Gram staining and KOH test were performed to confirm that the isolated bacterium is gram negative. The biochemical tests reveal that all the bacterial isolates are gram negative. Furthermore, two pathogenicity tests i.e. potato disc and carrot disc bioassay were conducted that confirmed the isolates causing tumors in the infected plant tissues. Antibiotic sensitivity tests reveal that the bacterial isolates are resistant to rifampicin antibiotic. All the morphological as well as the biochemical features of the bacterial isolates suggested that the samples isolated from crown galls were Agrobacterium tumefaciens. Our study provides the basis for further molecular characterization of the pathogens and to devise strategies for reducing the risk of bacterial infection and to enhance the yield of fruits.