Given below are five statements, arrange them in correct order:
A. Release of chemical signals by plant roots to attract bacteria
B. Formation of infection thread
C. Transformation of bacteria to bacteroid forms
D. Curling of root hair
E. Multiplication of root cortical cells to form nodules
Choose the correct answer from the options given below:
A. Release of chemical signals by plant roots to attract bacteria
B. Formation of infection thread
C. Transformation of bacteria to bacteroid forms
D. Curling of root hair
E. Multiplication of root cortical cells to form nodules
Choose the correct answer from the options given below:
Show Hint
- A, B, C, E, D
- D, A, B, E, C
- A, B, C, D, E
- A, D, B, E, C
The Correct Option is D
Solution and Explanation
Legume root nodule morphogenesis follows a strictly coordinated biochemical and cellular sequence.
Step 2: Detailed Explanation:
The sequential stages of root nodule organogenesis are:
1. Release of chemical signals (A): Plant root exudates secrete specific flavonoids and isoflavones to attract compatible rhizobia.
2. Root hair curling (D): Rhizobial Nod factors induce Shepherd's crook curling of the root hair.
3. Formation of infection thread (B): Rhizobia invade the root hair via an invaginating tubular infection thread.
4. Cortical cell division (E): Chemical signals stimulate inner root cortical cells to divide and form the nodule primordium.
5. Bacteroid differentiation (C): Rhizobia are released into nodule cells, differentiating into non-dividing, nitrogen-fixing bacteroids surrounded by symbiosome membranes.
Step 3: Final Answer:
Hence, the correct chronological sequence is A, D, B, E, C.
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