Contribution to Cytology of the Genus Euphorbia in Iran

Abstract

The species of E. spinidens, E. marschalliana, E. bungei, E. buhsei and E. szovitsii showed 2n=2x=20 while E. orientalis had 2n=2x=18 and E. helioscopia showed 2n=4x=42. The chromosome numbers obtained for E. szovitsii and E. helioscopia support the earlier reports, while the chromosome number of E. spinidens, E. marschalliana, E. bungei and E. buhsei are new to science. ANOVA and LSD tests revealed a significant difference for the size of the chromosomes, indicating the role of quantitative genomic changes in the Euphorbia species diversification. Euphorbia species differ in their karyotype formulae indicating the occurrence of structural changes in their chromosomes supported by meiotic chromosome pairing as quadrivalents were formed in diploid species due to heterozygote translocations. The occurrence of unreduced pollen grains was observed in the species showing tripolar cell formation.