The feedback control of the branched amino acid biosynthesis pathway in Arabidopsis is given below. The activity of Acetohydroxyacid Synthase (AHAS) enzyme is feedback inhibited by Leucine and Valine synergistically, whereas Isopropyl malate synthase (IPMS) enzyme activity is inhibited by Leucine only. Feedback-resistant mutant lines of AHAS and IPMS genes are ahas2-1D and ipms1-1D, respectively.
The phenotype of these feedback-resistant mutants was analyzed by growing them in the following Murashige and Skoog (MS) medium combinations.
A. MS medium only
B. MS medium supplemented with Leu only
C. MS medium supplemented with Val + Leu
D. MS medium supplemented with Val only
Which one of the following statements is correct?
1
ahas2-1D will grow in (C) only, and ipms1-1D will grow in (B) only.
2
ahas2-1D will grow only in (D) and ipms1-1D will grow in both (A) and (B).
3
ahas2-1D will grow in both (A) and (C) and ipms1-1D will grow in both (A) and (B).
4
Both ahas2-1D and ipms1-1D mutants will grow in (A) only.