Correct option is D
Explanation-
Strigolactones are plant hormones with three major roles:
1. Suppressing shoot branching (inhibiting axillary bud growth).
2. Stimulating arbuscular mycorrhizal (AM) fungi hyphal branching for symbiosis.
3. Stimulating germination of certain parasitic plants (like Striga and Orobanche).
In SL-deficient mutants, all these processes are disrupted.
Statements analysis -
Statement A: “Shoot branching gets enhanced in the mutant plant” - CORRECT
Normal SL function: Suppresses the growth of lateral (axillary) buds → reduces shoot branching.
In SL-deficient mutant: This suppression is missing → axillary buds grow freely → increased shoot branching.
Conclusion: Absence of SLs → enhanced shoot branching.
Statement B: “Hyphal branching of arbuscular mycorrhizal fungi (AM-fungi) gets enhanced during colonization in the mutant plants” - INCORRECT
Normal SL function: Stimulates hyphal branching in AM fungi to promote root colonization.
In SL-deficient mutants: Roots do not secrete SLs, so AM fungi are not stimulated → less hyphal branching and poor colonization.
Conclusion: Hyphal branching is reduced, not enhanced, in mutants.
Statement C: “Shoot branching gets inhibited in the mutant plants” - INCORRECT
This contradicts the known phenotype of SL mutants. SLs inhibit shoot branching, so if SLs are absent (as in the mutant), branching increases, not decreases.
Statement D: “Germination of seeds of parasitic plant is prevented near the mutant plant” - CORRECT
SLs are secreted into the soil by roots and act as chemical signals that trigger germination of parasitic plant seeds (like Striga). In mutants that don’t produce SLs, this signal is absent, so parasitic seeds do not germinate.
Final Answer:
Correct statements are A and D → Option d
