MICRB265 Lecture 18: MICRB 265 Lecture 18 Agrobacterium and Crown Gall Disease

• School: University of Alberta
• Department: Microbiology (Biological Sciences)
• Course: MICRB265
• Professor: Perrin Beatty

Document Summary

Note that only the t-dna has entered the plant cell, while the original bacterium remains outside: expression of t-dna genes in plant cell; These are exported from the plant roots into the rhizosphere where they induce the opine catabolism genes in the few a. tumefaciens cells that have the ti plasmid. The opine catabolism genes allow these cells to use the opines as a carbon and nitrogen source. Only the a. tumefaciens cells with ti plasmids benefit from this c+n source because other soil microbes lack these genes: conjugal transfer of ti plasmid in the rhizosphere, controlled by quorum sensing: The a. tumefaciens cells that can use the opines grow in number by utilizing the opines secreted by the plant into the rhizosphere. They then use quorum sensing (using homoserine lactones) to induce conjugal transfer of the ti plasmid to other a. tumefaciens cells in the rhizosphere.