Detoxification of phosphinothricin (glufosinate) Which gene product directly detoxifies the herbicide phosphinothricin by acetylation?

Introduction / Context:
Glufosinate (phosphinothricin) inhibits glutamine synthetase, leading to ammonium accumulation and plant death. Transgenic selection systems use an enzyme that inactivates this herbicide, enabling recovery of transformed tissues.

Given Data / Assumptions:

• PAT acetylates phosphinothricin, neutralizing its inhibitory activity.
• Nitrilases and GSTs detoxify other classes of herbicides (e.g., bromoxynil, atrazine) via different mechanisms.
• EPSPS is related to glyphosate tolerance, not glufosinate.

Concept / Approach:
Link the herbicide to its detox enzyme. For glufosinate, the answer is PAT (encoded by bar/pat). Nitrilase and GST are incorrect for this specific substrate.

Step-by-Step Solution:

Verification / Alternative check:
Vector maps and trait descriptions for glufosinate-tolerant crops reference PAT/Bar selection cassettes.

Why Other Options Are Wrong:

• Nitrilase: typically targets nitrile herbicides like bromoxynil.
• GST: catalyzes glutathione conjugation, often relevant to atrazine or safener responses, not direct acetylation of phosphinothricin.
• All of these: incorrect; only PAT is specific.
• EPSPS: pertains to glyphosate resistance.

Common Pitfalls:
Mixing up herbicide-resistance mechanisms across different chemistries.

Final Answer:
Phosphinothricin acetyl transferase (PAT)