Karyotype Analysis of Gazania rigens Varieties

For studying species origin, systematic evolution and phylogenetic relationship of Gazania rigens, four different G. rigens varieties, with different flower colors, were subjected to chromosome karyotype analysis. The somatic chromosome number in three varieties ‘Hongwen’, ‘Xingbai’ and ‘Richu’ was 2n = 10, while in ‘Zhongguo Xunzhangju’ it was 2n = 20. We speculate that the cardinal number of chromosomes in G. rigens plants is x = 5, in which case ‘Zhongguo Xunzhangju’ is a tetraploid. The karyotype formulae of ‘Hongwen’, ‘Xingbai’ and ‘Richu’ were 2n = 8m + 2sm, 2n = 8m + 2sm and 2n = 10m respectively. The karyotype formula of ‘Zhongguo Xunzhangju’ was 2n = 18m + 2sm. The asymmetrical karyotype coefficients of the four G. rigens varieties ranged from 53.80% to 58.84%. Only ‘Richu’ had a ‘1A’ karyotype, while the others were relatively symmetric ‘2A’. Karyotype analysis indicates that the three introduced varieties have a close genetic relationship.