Question

Why do legume plants have root nodules?​

Answer 1

Many legumes have root nodules that provide a home for symbiotic nitrogen-fixing bacteria called rhizobia. This relationship is particularly common in nitrogen-limited conditions. The Rhizobia convert nitrogen gas from the atmosphere into ammonia, which is then used in the formation of amino acids and nucleotides

Answer 2

Answer and Explanation:

Many legumes have root nodules that provide a home for symbiotic nitrogen-fixing bacteria called rhizobia. This relationship is particularly common in nitrogen-limited conditions. The Rhizobia convert nitrogen gas from the atmosphere into ammonia, which is then used in the formation of amino acids and nucleotides.Rhizobia normally live in the soil and can exist without a host plant. However, when legume plants encounter low nitrogen conditions and want to form a symbiotic relationship with rhizobia they release flavinoids into the soil. Rhizobia respond by releasing nodulation factor (sometimes just called nod factor), which stimulates nodule formation in plant roots. Exposure to nod factor triggers the formation of deformed root hairs, which permit rhizobia to enter the plant. Rhizobia then form an infection thread, which is an intercellular tube that penetrates the cells of the host plant, and the bacteria then enter the host plants cells through the deformed root hair. Rhizobia can also enter the root by inserting themselves between cracks between root cells; this method of infection is called crack entry. Bacteria enter the root cells from the intercellular spaces, also using an infection thread to penetrate cell walls. Infection triggers rapid cell division in the root cells, forming a nodule of tissue.