How do nitrogen-fixing microbes first become associated with their symbiotic plants?

Question

Quizplus · Accepted Answer

Nitrogen-fixing microbes first become associated with their symbiotic plants by entering via modified root hairs. These modified root hairs form a structure called a root nodule, where the microbes and the plant establish a symbiotic relationship. The microbes fix atmospheric nitrogen for the plant, and in return, the plant provides the microbes with carbohydrates and other nutrients.

How Do Nitrogen-Fixing Microbes First Become Associated with Their Symbiotic