GIBBERELLIC ACID-INDUCED GERMINATION OF SPORES OF ANEMIA PHYLLITIDIS: NUCLEIC ACID AND PROTEIN SYNTHESIS DURING GERMINATION

The distribution and synthesis of nucleic acids and proteins during gibberellic acid-induced germination of spores of Anemia phyllitidis were studied in order to relate biochemical activity with morphogenetic aspects of germination. Germination is accompanied by the hydrolysis of storage protein granules and the localized appearance of cytoplasmic RNA, protein, and insoluble carbohydrates in a small area adjoining the spore wall and surrounding the nucleus. The protoplast of the spore enlarges in this region, the spore wall breaks and a protonemal cell is formed which contains many chloroplasts. A second division in the spore at right angles to the first yields a rhizoid cell. Autoradiography of ³H-thymidine incorporation has shown that DNA is synthesized both in the nucleus and in the immediately surrounding cytoplasm of the germinating spore until some time after the first division, although a strictly nuclear DNA synthesis is observed later. Synthesis of RNA and proteins is limited to the presumptive regions of the germinating spore which become the protonema and rhizoid, shifting to specific sites in these cells as germination proceeds. The nucleus of the spore continues to be biosynthetically active long after it ceases to divide.