some plants have gene variations that allow them to be atraz

some plants have gene variations that allow them to be atrazine resistant. what protein(s) would have altered amino acid sequences as a result of these genetic variations? why?

Solution

Attained resistance is attributed to amino acid substitution of serine to Glycine at the 264th position which is also known as change in D1 protein structure in the thylakoid membrane of the chloroplasts. If serine is substituted with Alanine , low level of atrazine resistance is obtained.

The reason is that atrazine competes with plastoquinone for binding to QB protein which is a thylakoid protein. Thus atrazine interferes with phosynthetic electron transport in photosystem II. When plants having resistance to atrazine are made ther atrazine is not able to bind to QB.