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Abstract
Considered to be haploid tissue, the endosperm of coniferous trees has been extensively used by forest geneticists. Using laser flow cytometry, we show that endosperm ploidy level depends on the systematic position. The Abies, Cedrus and Pinus species tested exhibited uniform haploid endosperm compared to the diploid DNA content of the corresponding embryo. Endosperm of Cupressaceae contained multiple ploidy levels: Cupressus arizonica, Juniperus oxycedrus and Thuja orientalis endosperms exhibited a mixture of haploid-diploid nuclei, while C. atlantica and C. sempervirens endosperms contained six ploidy levels: 1C, 2C, 3C, 4C, 5C and 6C. Physiological and genetic implications of this original feature are discussed.[PUBLICATION ABSTRACT]