Revertant seedlings from crown gall tumors retain a portion of the bacterial Ti plasmid DNA sequences*
AUTOR(ES)
Yang, Funmei
RESUMO
BT37 is a crown gall teratoma incited on tobacco by Agrobacterium tumefaciens containing pTi-T37, a nopaline-type Ti plasmid. Treatment of this cloned tumor tissue with kinetin at 1 mg/liter results in the formation of relatively normal-appearing shoots. These shoots can be induced to root and set viable seed. In contrast to BT37 tissue, the derived tissues are not phytohormone independent and do not produce nopaline. The reverted plants, like normal tobacco plants, are susceptible to infection by A. tumefaciens. This loss of tumorous traits is accompanied by the loss of most of the Ti plasmid sequences (T-DNA) found in BT37 DNA. Southern blot analysis indicates that the revertant tissues have lost the central portion of the T-DNA, which contains the “common DNA” sequences, a highly conserved region of the Ti plasmid that has been found to be incorporated into all tumors studied. Thus, these sequences appear necessary for oncogenicity and tumor maintenance and their loss is probably directly related to tumor reversal. The reverted plants as well as the plants obtained from seed, however, do retain sequences homologous to the ends of the T-DNA present in the parental teratoma. The persistence of foreign DNA sequences during the process of meiosis and seed formation has important implications for the possibility of the genetic engineering of plants.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=319746Documentos Relacionados
- Proteins encoded by Agrobacterium tumefaciens Ti plasmid DNA (T-DNA) in crown gall tumors
- T-DNA from Agrobacterium Ti plasmid is in the nuclear DNA fraction of crown gall tumor cells
- Transcription of Ti plasmid-derived sequences in three octopine-type crown gall tumor lines.
- Crown gall tumors: are bacterial nucleic acids involved?
- Crown gall oncogenesis: evidence that a T-DNA gene from the Agrobacterium Ti plasmid pTiA6 encodes an enzyme that catalyzes synthesis of indoleacetic acid.