Effect of Actinomycin D and 2-Thiouracil on Floral Induction and Nucleic Acid Synthesis in the Bud in Chenopodium Amaranticolor

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Abstract
Actinomycin D and 2-thiouradl inhibit floral initiation in C. amaranticolor when applied to plants before the end of the inductive dark period. Actinomycin D does not suppress floral differentiation if it is applied to plants more than 48 hr. after the inductive dark cycle, whereas 2-thiouracil retains its ability to Interferewithfloral differentiation when applied to plants several days after the inductive dark period. A new, P32-labelled, ribonuclease-resistant RNA component was detected in apical buds following floral induction. Fractionation of P32 -labelled RNA isolated from induced apical buds on columns of methylated albumin on kieselguhr showed this to be associated with the DNA probably as a DNA-RNA hybrid. This RNA component was not detected in non-induced apical buds. Actinomycin D and 2-thiouracil decrease the incorporation of [P32]orthophosphate in into apical bud RNA in induced apical buds. Both inhibitors suppressed the appearance of the P32 -labelled, ribonuclease-resistant RNA component found in non-treated, induced apical buds. DNA-RNA nybrids may be needed for the synthesis of messenger RNA needed for floral bud differentiation.