Control of Chlorophyll Production in Rapidly Greening Bean Leaves

Levulinic acid inhibited the greening of etiolated maize (Zea mays) and bean (Phaseolus vulgaris) leaves and caused accumulation of 5-aminolevulinic acid (ALA). ALA accumulation in maize was equivalent to the decrease in chlorophyll, over a wide range of experimental conditions. It was saturated at low light intensities and was not limited by the supply of substrates during the early hours of greening. During 20 hours in light, levulinic acid had little effect on the structural development of thylakoids in bundle sheath chloroplasts but significantly reduced the number and size of thylakoids in grana of mesophyll chloroplasts. Recrystallization of prolamellar bodies and their reformation was inhibited. Mitochondria appeared not to be affected.The accumulation of ALA in bean leaves differed from that in maize in regard to its time course and the effect of levulinic acid concentration and light intensity. The amount of ALA accumulated exceeded that expected from the degree of inhibition of chlorophyll synthesis. Levulinic acid caused abnormalities in the structural development of bean chloroplasts and marked swelling of mitochondria.Chloramphenicol and cycloheximide inhibited ALA accumulation, whlile inhibitors of RNA synthesis had no effect. The extent of inhibition depended on the time the inhibitor was applied during the greening process. The use of ALA accumulation as a tool for studying the control of chlorophyll synthesis is discussed.

Section: Discussionsupporting

confidence: 80%

Accumulation of δ-Aminolevulinic Acid and Its Relation to Chlorophyll Synthesis and Development of Plastid Structure in Greening Leaves

Klein¹,

Harel²,

Ne’eman³

et al. 1975

“…2 inset) is consistent with the notion that protein synthesis controls the accumulation of Chl in Mg-deficient photoheterotrophic Euglena. This conclusion is further supported by evidence that protein synthesis is required for normal Chl production when etiolated plant tissues are exposed to light (6,9). In view of this seeming dependency, it is surprising to find that the rate of Chl accumulation, while parallel to, is always greater than the rate of protein synthesis.…”

Section: Methodssupporting

confidence: 64%

Relative Requirements for Magnesium of Protein and Chlorophyll Synthesis in Euglena gracilis

Zielinski

Price²

1978

“…(6,7,10,19). Gassman and Bogorad (7) reported that after hours of cycloheximide pretreatment in the dark a single protochlorophyllide regeneration can be induced, but the drug is known to inhibit massive greening.…”

Section: Methodsmentioning

confidence: 99%

Relationship between Photoconvertible and Nonphotoconvertible Protochlorophyllides

Murray

Klein

1971