|MadSci Network: Microbiology|
Some general information to your question can be found in a madsci answer to an earlier Agrobacterium question --> click here . This answer includes links that will address your question regarding plant host range as well as how to cause a high infection rate within a plant. In nature the infection occurs through small wound sites on the plants stem that may have been caused by physical damage or damage from insect feeding on the plant.
I did a quick web search using the Google search engine and found one site that describes a science project similar to the one you propose: How effective is beta-carotene in fighting cancer in plants?
While conducting your experiment keep in mind that b-caroteneís suggested role in decreasing risks of cancer stems from mammalian studies. In mammals, b-carotene is converted into vitamin A, or retinol, which is essential for normal development in humans and other mammals, and serves to support the immune system and act as an antioxidant. It is in support of the immune system that b-carotene is indirectly (though vitamin A) thought to reduce cancer risks in mammals and also with its role as an antioxidant.
Good luck with your experiments and donít forget to include your controls (a good experiment is only as good as the controls chosen to support the data).
Try the links in the MadSci Library for more information on Microbiology.