Soybean plant and Rhizobium bacteria's "special relationship"

Soybean plants' roots would emit a chemical signal that is attractive to Rhizobium bacteria. The bacteria would respond with signals that causes the root hairs to elongate; allowing the bacteria to infect the plant by penetrating and causing the invagination of the plasma membrane.

The Rhizobium bacteria would then penetrate the root cortex within the "infection thread". Root cortex cells and pericycle cells would begin to divide. Growth would continue in the affected regions of the cortex and pericycle until the two dividing cells fuse, which forms the root nodule. The nodule would continue to grow while vascular tissues connect the nodule to the xylem and phloem. The vascular tissue would supply nutrients to the nodule as well as carry nitrogenous compounds out from the nodule to be distributed to the rest of the plant.

Soybean plants and Rhizobium bacteria have a type of symbiosis relationship. They exhibit a mutualistic relationship, or cooperation, due to the fact that the Rhizobium bacteria supplies the soybean plant with fixed nitrogen while the soybean plant provides the Rhizobium bacteria with carbohydrates and other organic compounds that helps the bacteria to grow.

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