Monthly alterations in macromolecular contents of in situ ovules excised from Georgian Pinus taeda L.

Abstract

Pinus taeda L. (loblolly pine), a commercial timber three of the Southeastern United States, provides a major component of the region's forest resources. We cultured loblolly ovules for in vitro fertilization. This procedure was assisted by quantifying time-dependent alterations of in situ ovular RNA, DNA and total protein (Jan-Aug, 1985) contents for ovules (yr 2 of reproductive cycle). Cold-hot, TCA extracted macromolecules were quantified by colorimetry and UV spectroscopy. Total protein was about 0.4 µg per 100 ovules x 10⁴ (Jan-Apr) and except for July increased to 3.6 µg per 100 ovules x 10⁴ by August. In contrast, RNA "dropped" from 3 to about I µg per 100 ovules x 10² (Jan-Mar) and then rose to 7 µg per 100 ovules x 10² by July. The DNA climbed from about I to above 8 µg per 100 ovules x 10² (Jan-Mar) and then plummeted to I µg per 100 ovules x 10² (Apr-June). The observed alterations may reflect ovule morphogenesis.