124 Bulgarian Journal of Agricultural Science, 25 (Suppl. 3) 2019 Agricultural Academy Karyological study of genus Oxybasis Kar. & Kir. in Bulgaria Neli Grozeva 1 , Stefka Atanassova 2 , Svetoslava Terzieva 1 1 Trakia University, Faculty of Agriculture, Department of Biology and Aquаculture, 6000 Stara Zagora Bulgaria 2 Trakia University, Faculty of Agriculture, Department of Biochemistry, Microbiology and Physics, 6000 Stara Zagora Bulgaria * Corresponding author: grozeva@uni-sz.bg Abstract Grozeva, N., Atanassova, S. & Terzieva, S. (2019). Karyological study of genus Oxybasis Kar. & Kir. in Bulgaria. Bulg. J. Agric. Sci., 25 (Suppl. 3), 124–130 A karyological study of Oxybasis chenopodioides, O. glauca, O. rubra and O. urbica was conducted and the karyotype morphology from their Bulgarian populations was reported for the first time. The studied species showed 2n = 2x = 18 and differed significantly in total size of chromosomes, the size of the long and the short arms. The karyotype consists of metacen- tric and submetacentric chromosomes and their size varied from 0.8 to 3.12 μm. Clustering of the species based on karyotype features grouped them in 2 clusters: O. chenopodioides with O. glauca and O. rubra with O. urbica with greater karyotype similarity found between O. rubra and O. urbica. The idiograms of all studied populations have been illustrated. Keywords: Oxybasis; karyotype; Bulgaria; idiograms Introduction Chenopodium L. is one of the big and most difficult taxo- nomically genera in the family Amaranthaceae. Molecular phylogenetic studies in recent years revealed that Chenopo- dium L. is polyphyletic, and its representatives have been placed in several genera – Chenopodium, Blitum, Chenopo- diastrum, Oxybasis, Lipandra, Dysphania, Teloxys (Kadereit et al., 2003; 2010; Fuentes-Bazan et al., 2012a,b). Genus Oxybasis Kar. & Kir. comprises the species from sect. Pseu- doblitum of genus Chenopodium s.l. Genus Oxybasis is characterised in having flowers with a hyaline or greenish perianth of 2-4(5) free or connate seg- ments, a reduced number of stamens (2-4, rarely 5) and usu- ally red seeds with the outer layer (testa) impregnated with tannin-like substances and a diversely oriented seed embryo (Fuentes-Bazan et al., 2012b; Sukhorukov & Zhang, 2013; Sukhorukov et al., 2013). For the Bulgarian flora up to this moment a total of 4 species of genus Oxybasis have been reported – Oxybasis chenopodioides (L.) S. Fuentes, Uotila & Borsch. (syn.: Chenopodium chenopodioides L.), Oxybasis glauca (L.) S. Fuentes, Uotila & Borsch L. (syn.: C. glaucum L.), Oxyba- sis rubra (L.) S. Fuentes, Uotila & Borsch (syn.: C. rubrum L.), Oxybasis urbica (L.) S. Fuentes, Uotila & Borsch (syn.: Chenopodium urbicum L.) (Yordanov et al., 1966; Andreev, 1992; Assyov & Petrova, 2012). O. chenopodioides was reported for the first time for the Bulgarian flora by Andreev (1992) for the area of the North- ern Black sea coast without any clear motives about that. Upon review of the materials in the Bulgarian scientific her- baria it has been found that prof. P. Uotila upon review of the herbarium samples deposited at the Faculty of Biology at Sofia University in 1993 referred two of them to C. chenopo- dioides: SO No82609 (sub C. rubrum L.) from the region of Durankulak lake and SO No18126 (sub Atriplex hastata L.) from Shabla lake. The species prefers saline coastal sunny ruderalized terrains (Uotila, 2001). Oxybasis glauca occurs most frequently along the Black Sea coast and in the inland of the country it usually grows