Cytotaxonomy of Four Species of Sterigmostemum (Brassicaceae) in Iran

Abstract

Cytological studies on 4 Sterigmostemum species of St. ramosissim, um, St. incanum, St. sulphureum and St. acanthocarpum showed the presence of 2n=2x=14, out of which the chromosome number of St. ramosissimum is new. The chromosomes were mainly metacentric or sub-metacentric ranging in size from 2.62 μm in St. ramosissimum to 5.50 μm in St. sulphureum and St. acanthocarpum. The species studied formed mainly ring and rod bivalents as well as univalents in metaphase of meiosis I, but a low value of quadrivalents were formed in the Firoozkooh population of St. sulphoreum and the Tehran population of St. acanthocarpum possibly due to the occurrence of heterozygote translocations. Clustering and parsimony analysis of cytological data showed close affinity between St. incanum and St. sulphureum, supporting morphometric and seed protein studies results.