Answer
If monopteros protein cannot bind its repressor, it will always be active, behaving as if auxin is present. This will lead to the formation of many, many roots.
Work Step by Step
The key is to see in Fig. 41.32 that the repressor is normally unable to bind monopteros protein when auxin is present, leading to root formation. The mutation described in the question acts like a large dose of auxin.
