Which bacterium causes crown gall disease in plants and transfers DNA into plant cells?

Agrobacterium tumefaciens causes crown gall disease in plants and transfers DNA into plant cells.

The bacterium typically enters through wounds near the soil line. It carries a tumor-inducing, or Ti, plasmid. A segment called T-DNA is transferred into the plant cell and becomes integrated into the plant’s genome. The altered cells produce plant hormones that stimulate an abnormal gall, along with compounds the bacterium can use as nutrients.

Scientists turned this natural gene-transfer system into a major tool for plant biotechnology. Modified Agrobacterium can deliver useful genes without causing disease, helping researchers create genetically engineered plants. The species is now often called Rhizobium radiobacter because of taxonomic revisions, but Agrobacterium tumefaciens remains the widely recognized name. Crown gall is not a fungal tumor: it is a bacterial disease caused by altered plant growth.