Changing patterns of nucleic acids, basic and acidic proteins in generative and vegetative nuclei during pollen germination and pollen tube growth in Hippeastrum belladonna

Abstract

Generative and vegetative nuclei of mature and germinated pollen grains from Hippeastrum belladonna were separated in a continuous Ficoll gradient. Less than 3% contamination was observed between the generative and vegetative nuclear fractions. The vegetative nuclei were composed of two populations; the larger population consisted of nuclei with 1C levels of DNA and the smaller with 2C levels. The generative nuclei consisted of a homogeneous population composed of nuclei possessing 2C levels of DNA. Histone synthesis did not occur in vegetative nuclei. Changes appeared in the gel-electrophoretic banding patterns of the F1 histones of vegetative nuclei during germination. Changes were not observed in the generative nuclei. A reduction of general proteins and RNA was observed in vegetative nuclei by 20 h of germination. The phenol-soluble nuclear proteins of vegetative nuclei revealed transitions in electrophoretic banding patterns during pollen germination that were greater than those shown by the histones. These changes in the PSNP primarily involved reduced concentrations of certain proteins rather than synthesis of new ones. However, a new band was observed in the electrophoretic pattern of the PSNP of vegetative nuclei after 12 h of pollen tube growth. No transition was seen in the PSNP of generative nuclei during pollen germination and tube growth. The regulatory role of the PSNP in cell differentiation is discussed in the light of these findings.