Trace the events starting from the coming in contact of Rhizobium to a leguminous root till nodule formation. Add a note on the importance of leghemoglobin.

(N/A) The process of nodule formation involves the following steps:
$1$. Rhizobium bacteria contact a susceptible root hair and divide near it.
$2$. The infected root hair curls,and the bacteria invade the root hair.
$3$. An infection thread is produced,which carries the bacteria into the inner cortex of the root.
$4$. The bacteria are released from the thread into the cells,where they differentiate into rod-shaped bacteroids.
$5$. This triggers cell division in the cortex and pericycle,leading to the formation of root nodules.
$6$. The mature nodule establishes a direct vascular connection with the host plant for nutrient exchange.
Importance of Leghemoglobin:
Leghemoglobin is a pink-colored pigment found in the root nodules of leguminous plants. Its primary function is to act as an oxygen scavenger. The enzyme nitrogenase,which is responsible for nitrogen fixation,is highly sensitive to molecular oxygen. Leghemoglobin creates a low-oxygen environment within the nodule,protecting the nitrogenase enzyme from oxidative damage while allowing sufficient oxygen for bacterial respiration.