معرفی گونه Agrobacterium deltaense و گونه ژنومی G19 عامل گال طوقه از میزبان‌های چغندرقند وگل رز برای اولین بار در ایران

Agrobacteria are soil bacteria that for more than a century have been known as causative agent of crown gall and hairy root diseases on a broad range of plant species. since A. tumefaciens is not a homogenous species and that’s why defined as “species complex(“A. tumefaciens species complex”). Five out of eleven genomospecies(G2,G4,G7,G8,and G14) have valid binominals nomenclature .In this study, we determined the pathogenicity and phylogenetic characteristics of 12 strain of Agrobacterium spp. associated with crown galls symptoms on sugar beet(Beta vulgaris) and rose(Rosa spp.) from Fars, Isfahan and Kohgiluyeh-Boyer-Ahmad provinces in Iran. The identity of the bacterial isolates were determined using the Agrobacterium and pTi specific primers virD2A/virD2C ,tms2F1/ tms2R2 and F8360/F8361. Pathogenicity tests were conducted on tomato (Solanum lycopersicum cv. Sunseed 6189) and Christmas kalanchoe (Kalanchoe blossfeldiana) plants in greenhouse conditions. Phylogenetic analysis based on two housekeeping genes – gyrB and recA used in this study. amplification of gyrB and recA genes was performed with F61/R1093 and F7386/ArecAR primers ,respectively and the certificated PCR products were sent to Bioneer Corporation (http//:www.Bioneer.com) to be sequenced via Sanger sequencing technology. Phylogenetic analysis was performed using maximum likelihood method with MEGA 6.06 software. Crown gall symptoms appeared two weeks post inoculation on the tested plants .All strains were pathogenic on tomato and Christmas kalanchoe plants. Amplification of 224 bp and 617 bp fragment using the primer pairs virD2A/virD2C and tms2F1/ tms2R2 in all the 12 isolates confirmed that they possess Ti plasmid . The primer pair F8360/F8361directed to amplify 453 bp fragment in all isolates indicating that these isolates belong to Agrobacterium spp. Phylogenetic analysis based on the data set of concatenated sequences of gyrB and recA genes showed that eight strains isolated from sugar beet and rose were clustered as Agrobacterium deltaense ,based on concatenated sequences of gyrB and recA genes phylogeny. In previously studies, this new species was isolated from Sesbania (Sesbania cannabina), Malus sp. and Indian plum (Flacourtia indica) . In this study two spices plant, sugar beet and rose, were introduced as new hosts for A. deltaense.Genomospecies G3 included only the strain SB4 isolated from sugar beet in Eghlid county, Fars province. Three strains (i.e. Rnr, Rnw and Rew) isolated from rose in 2016 were designated as a new genomospecies G19. In this study we propose a new genomospecies G19 among “A. tumefaciens species complex” (biovar 1).Nevertheless, additional studies are needed to determine if the G19 strains represent a novel species.