Synthesis of Plastid and Cytoplasmic Ribosomal RNAs in Isolated Pumpkin Cotyledons: I. Effect of Detachment and Light

Abstract

Summary During the first four days of pumpkin seed germination in darkness both cytoplasmic and etioplast rRNAs accumulate in cotyledons of intact seedlings. The cotyledons isolated from dry seeds can grow without embryonic axis in darkness. The isolation accelerates the rate of both cytoplasmic and plastid ribosomal RNA accumulation in cotyledons during 72 h of their development, in comparison to those of attached etiolated seedlings. Light markedly stimulates both the growth of isolated cotyledons and the increase in amount of the two ribosomal RNAs, but this effect is more pronounced in the accumulation of chloroplast rRNA.