Host range of Agrobacterium tumefaciens Ti plasmid Which of the following crops is naturally killed by Ti plasmid infection causing crown gall disease?

Introduction / Context:
Agrobacterium tumefaciens carries the Ti (tumor-inducing) plasmid and causes crown gall disease in many dicotyledonous plants. Understanding its host range is foundational for both plant pathology and for Agrobacterium-based transformation strategies.

Given Data / Assumptions:

• Rice, corn, and sorghum are monocot crops.
• Agrobacterium tumefaciens naturally infects mainly dicots under field conditions.
• Modern lab protocols can transform some monocots artificially, but this differs from natural disease susceptibility.

Concept / Approach:
The question asks which crop is “killed” by Ti plasmid infection (i.e., natural disease). Monocots typically do not develop crown gall in nature. Therefore, among rice, corn, and sorghum, none are natural hosts for Ti-mediated tumor formation that would lead to plant death.

Step-by-Step Solution:

Verification / Alternative check:
Plant pathology references and extension bulletins note crown gall predominates in dicots (e.g., grapes, roses, stone fruits), not cereals or other monocots.

Why Other Options Are Wrong:

• Rice, corn, sorghum: not natural Ti hosts; listing any one as susceptible is incorrect.
• All of these: contradicts the established host range.

Common Pitfalls:
Equating laboratory Agrobacterium transformation of monocots (achieved with special methods) with natural disease susceptibility.

Final Answer:
None of these (monocots are not natural Ti hosts)