Role of c2 in the gene action sequence

The c2 mutant aleurone extracts were analyzed by paper, TLC and spectrophotometrically. The Rf values obtained with BAW and Forestal (0.40 and 0.81) and U.V. absorption maxima at 270 µ and 222 µ suggest that the unknown sample may be cinnamic acid.

The fact that c1 can synthesize cyanidin with cinnamic acid and caffeic acid and c2 with naringenin suggests that the c1 block may be before cinnamic acid, whereas c2 may be after cinnamic acid but before the flavanone/C-15 intermediate step. The fact that c2 accumulates cinnamic acid suggests that c2 may be blocking before the C-15 intermediate stage.

These observations independently confirm the earlier gene action sequence of Reddy & Coe (1961 MGCNL) where it was suggested that c2 follows c1 in the sequence. Since c1 can utilize cinnamic acid (without hydroxyl groups) to synthesize cyanidin (with 3' and 4' hydroxyl groups) it may be possible that 3' and 4' hydroxylation (controlled by the Pr/pr gene) may be occurring after c1 in the sequence and probably after the C-15 intermediate formation.

Padma Balaravi and G. M. Reddy


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