Engineering atrazine tolerance Which gene has been transferred into plants to detoxify the herbicide atrazine through conjugation or degradation pathways?

Introduction / Context:
Atrazine is a triazine herbicide. Plants can gain tolerance via enhanced detoxification, notably by conjugation with glutathione catalyzed by glutathione S-transferases (GSTs), or by bacterial enzymes that degrade atrazine. Understanding which gene families are relevant guides trait design.

Given Data / Assumptions:

• GSTs catalyze GSH conjugation of electrophilic herbicides including atrazine.
• bxn nitrilase targets bromoxynil, not atrazine.
• PAT inactivates glufosinate, not atrazine.
• EPSPS is the glyphosate target enzyme; glyphosate traits are unrelated to atrazine.

Concept / Approach:
Match herbicide to known detox pathway: for atrazine, enhanced GST activity is a classic route, and transgenic overexpression of GSTs has been used to increase tolerance in some species. Therefore, select GST.

Step-by-Step Solution:

Verification / Alternative check:
Weed science and plant biotech literature report atrazine metabolism via GST-mediated conjugation; safeners also induce GSTs, increasing tolerance.

Why Other Options Are Wrong:

• Nitrilase (bxn): specific to bromoxynil detox, not atrazine.
• PAT: specific to glufosinate (phosphinothricin), not atrazine.
• All of these: incorrect because the listed enzymes do not all target atrazine.
• EPSPS: glyphosate-related, not atrazine.

Common Pitfalls:
Confusing different herbicide classes and assuming one resistance gene covers many modes of action.

Final Answer:
Glutathione S-transferase (GST)