New class of limited-host-range Agrobacterium mega-tumor-inducing plasmids lacking homology to the transferred DNA of a wide-host-range, tumor-inducing plasmid.
AUTOR(ES)
Unger, L
RESUMO
Biotype 1 and 2 strains of Agrobacterium tumefaciens were isolated from crown gall tumors of Lippia canescens plants growing as ground cover in Arizona. The isolates were agrocin 84 sensitive, did not catabolize octopine, nopaline, agropine, or mannopine, and were limited in their tumorigenic host range. One biotype 2 strain, AB2/73, showed the most limited host range; it incited tumors only on Lippia strains, the cucurbit family of plants, and Nicotiana glauca. Megaplasmids were detected in the isolates by vertical agarose gel electrophoresis. The unusual host range, as well as sensitivity to agrocin 84, were plasmid specified since they were conjugally cotransferred with plasmids from donor strain AB2/73. Correlation of deletions with concomitant loss of virulence and agrocin 84 sensitivity identified the megaplasmid pAtAB2/73d as the virulence element in strain AB2/73. The estimated size of this tumor-inducing plasmid was 500 kilobases. Axenic growth of tumor tissue incited by strains carrying pAtAB2/73d was phytohormone independent. Although the limited-host-range megaplasmid pAtAB2/73d lacked any detectable homology to the phytohormone-biosynthetic genes in wide-host-range transferred DNA (tms-1, tms-2, tmr), it showed homology to the wide-host-range virB, virC, virD, and virG loci. Therefore, pAtAB2/73d represents a new class of tumor-inducing plasmids distinguished by its large size, the absence of determinants for the catabolism of several known opines, the presence of agrocin 84 sensitivity, and its lack of homology to wide-host-range transferred DNA contrasted with its conservation of sequences from the wise-host-range vir region.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=214312Documentos Relacionados
- Limited-host-range plasmid of Agrobacterium tumefaciens: molecular and genetic analyses of transferred DNA.
- Comparison of T-DNA oncogene complements of Agrobacterium tumefaciens tumor-inducing plasmids with limited and wide host ranges.
- Tumor-inducing (Ti) plasmids of Agrobacterium share extensive regions of DNA homology.
- Hairy-root-inducing plasmid: physical map and homology to tumor-inducing plasmids.
- Multiple mutations in the T region of the Agrobacterium tumefaciens tumor-inducing plasmid.