Genetic diversity of Iranian Agrobacterium strains from grapevine

Abstract

Crown gall of grapevine is an economically important disease in all areas where grapes are grown, but it is particularly severe in regions with cold climates. The purpose of this study was twofold: (1) to compare available Agrobacterium primer sets and identify a more reliable PCR analysis that can detect tumorigenic and non-pathogenic A. vitis and A. tumefaciens strains involved in the crown gall disease of grapevines in Iran and (2) to detect the genetic diversity of these strains by insertion sequence 50 (IS50) PCR as the genetic marker. Based on the results of morphological, physiological, biochemical, and pathogenicity tests and amplification of the virD2 gene fragment and subsequent comparison of IS50-PCR fingerprints of the strains, we identified 27 of all 40 strains tested as tumorigenic A. vitis, three strains as non-tumorigenic A. vitis, and ten strains as tumorigenic A. tumefaciens. The similarity of all pairwise combinations was determined using Jaccard’s coefficient, and cluster analysis was performed using the unweighted pair group method with arithmetic average (UPGMA) clustering. On the basis of the fingerprint patterns generated by IS50-PCR,, the isolated strains were differentiated into four clusters (A–D) at the 60% similarity level. These four clusters could be further divided into several subgroups at the 80% similarity level. These results demonstrate that there is a wide variation in the sensitivity patterns of different Agrobacterium strains to different antibiotics.