The Abolition of the Lag Phase in Greening Cucumber Cotyledons by Exogenous delta-Aminolevulinic Acid.

Etiolated cucumber cotyledons treated with delta-aminolevulinic acid accumulated protochlorophyllide which was phototransformable to chlorophyll (ide). The phototransformation process in the delta-aminolevulinic acid-treated tissue was markedly temperature-dependent, consistent with the view that this protochlorophyllide must combine with the holochrome apoenzyme before phototransformation can occur.The treatment which effects lag phase removal in control tissue did not affect the course of chlorophyll (ide) accumulation in delta-aminolevulinic acid-treated tissue under either continuous or intermittent illumination. It was concluded that the lag phase in etiolated tissues must reflect the gradual development of the ability to synthesize delta-aminolevulinic acid at an appreciable rate.