Chloroplast Biogenesis, Its Inhibition and Modification by New Herbicide Compounds

Biogenesis and development of chloroplasts are summarized in the light of new findings; the interactions of different groups of photosynthetic herbicides with chloroplast development are indicated. The effect of two new active ingredients, mevinolin* and sethoxydim **, on chloroplast modification and biogenesis are described. Mevinolin blocks the cytoplasmic HMG-CoA reductase and sterol accumulation and modifies chloroplast differentiation via the formation of a sun-type chloroplast. Sethoxydim inhibits leaf growth in grasses and gramineous crop plants and strongly affects chloroplast biogenesis and differentiation at all stages of development from proplastids via prochloroplasts to young and mature chloroplasts. This applies to thylakoid formation and multiplication, grana formation as well as chloroplast division and chlorophyll and carotenoid accumulation. The chlorophyll fluorescence induction kinetics (Kautsky effect) indicate that photosynthesis is not affected. At higher doses sethoxydim stops all growth responses of maize plants and induces the accumulation of anthocyanins.