Changes in nucleic acid and protein levels during in vitro germ¬nation and elongation of Lilium longifforum cv. "Ace" polleni

Abstract

While changes in nucleic acid and protein levels during germination and subsequent tube elongation have been determined for a number of pollens, they have not been extensively examined for in vitro grown Lilium longiflorum, cv. `Ace' pollen. Nucleic acids and proteins were extracted with cold trichloroacetic acrid (TCA), cold-hot TCA or cold TCA and potassium hydroxide-perchloric acid (KOH-HClO₄). Following extraction, RNA, DNA and total protein were assayed colorimetrically with orcinol, diphenylamine and Folin-Phenol reagents, respectively. Extraction of 500 x g supernatants with KOH-HClO₄, yielded less RNA than either of the TCA-extraction procedures which gave similar nucleic acids and protein recoveries. Whereas total protein levels decreased initially and then increased during 36 h, RNA and DNA levels rose throughout the time-course. Precipitation and quaritiation of nucleic acids and protein from homogenized and soaicated 500 x g pellets resulted in time-dependent alterations in levels of macromolecules which differed from those for 500 x g supernatants. Whereas DNA and RNA levels increased and then decreased over 36 h, total protein levels remained constant for 12 h and then declined during the : next 24 h. Addition of the data obtained for 500 x g supernatants to those for 500 x g pellets revealed that total protein levels increased 2.4 times for the first 12 h and thereafter remained constant, that RNA levels increased 9.8 times for the first 12 h and then levelled off and that the DNA content rose more than 5 times over 36 h.