The given figure indicates the development of root nodule in soyabean

Identify A, B, C and D respectively

Options

A. A - Nitrosomonas bacteria, B - Cortex cell, C - Inner cortex, D - Infection thread
B. A - Rhizobial bacteria, B - Endodermal cell, C - Inner Endodermis, D - Infection thread
C. A - Rhizobial bacteria, B - Cortex cell, C - Inner cortex, D - Infection thread
D. A - Rhizobial bacteria, B - Cortex cell, C - Outer cortex, D - Infection thread

Answer

C

Explanation

Rhizobium multiplies and colonize the surroundings of roots and gets attached to epidermal and roots hair cells. This occurs because legume roots secrete some specific chemicals which attract the bacteria.
* Bacteria collect over the root hairs release Nod factors that cause curling of root hairs and the bacteria invades them. An infection thread containing the bacteria is produced. Infection thread grows along with multiplication of bacteria. * Infected thread carries the bacteria to the inner cortex where they initiate the nodule formation. * The invading bacteria stop dividing and get modified into rod-shaped structure called bacteroids. * Also the bacteria release signals that cause inner cortical and pericycle cell to divide. * Division and growth of cortical and pericycle cells lead to nodule formation.