Aphidicolin and ethidium bromide as tools to verify dependence of early post‐germinative growth on nuclear and organellar DNA synthesis

Abstract

Embryos of Haplopappus gracilis (Nutt.) Gray were sown in aphidicolin (inhibitor of nuclear DNA synthesis) used alone or in combination with ethidium bromide (inhibitor of organellar DNA synthesis). In both cases germination and the early processes of post‐germinative growth, including enlargement and greening of cotyledons, some elongation of radicle, and formation of root hairs, occurred at the same rate as in the controls. Comparable results were obtained using fluorodeoxyuridine. The effect of aphidicolin is, unlike fluorodeoxyuridine, completely reversible and the side effect on protein and RNA synthesis are negligible. Total non‐dependence on nuclear and organellar DNA synthesis during early post‐germinative growth may not be a generalized situation in all seeds, as was shown by some observations on lettuce and watermelon.