Lack of mother tree alleles in zymograms of Cupressus dupreziana A. Camus embryos

Abstract

Unexpected ploidy levels observed in a previous flow cytometric analysis of Cupressus dupreziana endosperm, led us to hypothesize an asexual seed production in this endangered species. We tested here this possible apomixis, studying isozyme variability of endosperms, embryos and seed coats extracted from open pollinated seeds. Electrophoretic bands observed in zymograms of PGI2 and LAP, the only two polymorphic systems, were in agreement with bands observed in C. sempervirens zymograms. Zymograms of C. dupreziana endosperms were identical to those of the diploid maternal tissue, as observed in C. sempervirens. Hypothesizing a codominant nuclear DNA control for both PGI2 and LAP, a similar electrophoretic expression of these systems in endosperm and embryo, and the absence of modifier genes, the lack of endosperm bands in most embryo zymograms was interpreted as the result of a strictly paternal origin of embryo nuclear DNA in C. dupreziana seeds.