FLOW CYTOMETRIC EVIDENCE FOR MULTIPLE PLOIDY LEVELS IN THE ENDOSPERM OF SOME GYMNOSPERM SPECIES

Considered to be haploid tissue, the endosperm of coniferous trees has been extensively used by forest geneticists. Using laser flow cytomet ry, we show that endosperm ploidy level depends on the systematic posi tion. The Abies, Cedrus and Pinus species tested exhibited uniform hap loid endosperm compared to the diploid DNA content of the correspondin g embryo. Endosperm of Cupressaceae contained multiple ploidy levels: Cupressus arizonica, Juniperus oxycedrus and Thuja orientalis endosper ms exhibited a mixture of haploid-diploid nuclei, while C. atlantica a nd C. sempervirens endosperms contained six ploidy levels: 1C, 2C, 3C, 4C, 5C and 6C. Physiological and genetic implications of this origina l feature are discussed.