Crown Gall infection is linked to which seasonal condition that allows bacterial invasion?

Crown Gall infection is linked to which seasonal condition that allows bacterial invasion?

• A. Summer drought
• B. Winter freezes causing trunk rupture
• C. Spring rains
• D. Autumn leaf drop

Answer: (B)

The key idea is that crown gall infection requires a wound through which the bacterium can enter the plant. Winter freezes causing trunk rupture create precisely the kind of opening the pathogen needs to invade the plant tissue. Agrobacterium tumefaciens lives in the soil and relies on wounds in stems or roots (often at the crown) to gain entry; once inside, it disrupts normal cell growth and forms the characteristic galls. Other seasonal scenarios don’t provide the same specific entry point. A summer drought doesn’t create a wound in the trunk for invasion; spring rains may help spread bacteria but don’t inherently open a wound, and autumn leaf drop doesn’t create a lesion at the crown that would allow entry.

The key idea is that crown gall infection requires a wound through which the bacterium can enter the plant. Winter freezes causing trunk rupture create precisely the kind of opening the pathogen needs to invade the plant tissue. Agrobacterium tumefaciens lives in the soil and relies on wounds in stems or roots (often at the crown) to gain entry; once inside, it disrupts normal cell growth and forms the characteristic galls.

Other seasonal scenarios don’t provide the same specific entry point. A summer drought doesn’t create a wound in the trunk for invasion; spring rains may help spread bacteria but don’t inherently open a wound, and autumn leaf drop doesn’t create a lesion at the crown that would allow entry.