Control of chlorophyll synthesis by phytochrome : II. The effect of phytochrome on aminolevulinate dehydratase in mustard seedlings.

The activity of aminolevulinate dehydratase in mustard (Sinapis alba L.) seedlings increases in continuous far-red light. The light effect can be attributed to phytochrome.

Control of chlorophyll synthesis by phytochrome : I. The effect of phytochrome on the formation of 5-aminolevulinate in mustard seedlings.

Treatment of mustard (Sinapis alba L.) seedlings with levulinate leads to the inhibition of chlorophyll synthesis and causes the accumulation of 5-aminolevulinate which is only formed in light. A stoichiometric relationship exists between the extent of inhibition of chlorophyll synthesis and 5-aminolevulinate accumulation.

Accumulation of protochlorophyll and chlorophyll a as controlled by photomorphogenically effective light.

Data are presented which indicate that the rate of synthesis and the pool size of photoconvertible protochlorophyll(ide) in the cotyledons of the mustard seedling are controlled by the active form of phytochrome (Pfr). Inductionreversion experiments show that formation of chlorophyll a through photoconversion of the protochlorophyll(ide) by repeated red pulses (5 min each) has no effect on synthesis of carotenoids and galactolipids. Since the protochlorophyll(ide)-converting activity of the standard far-red light used in this laboratory is very low, chlorophyll-a accumulation is very slow under continuous standard far-red light.