rDNA mapping, heterochromatin characterization and AT/GC content of Agapanthus africanus (L.) Hoffmanns (Agapanthaceae)

Abstract

Agapanthus (Agapanthaceae) has 10 species described. However, most taxonomists differ respect to this number because the great phenotypic plasticity of the species. The cytogenetic has been an important tool to aid the plant taxon identification, and to date, all taxa of Agapanthus L'Héritier studied cytologically, presented 2n = 30. Although the species possess large chromosomes, the group is karyologically little explored. This work aimed to increase the cytogenetic knowledge of Agapanthus africanus (L.) Hoffmanns by utilization of chromosome banding techniques with DAPI / CMA 3 and Fluorescent in situ Hybridization (FISH). In addition, flow cytometry was used for determination of DNA content and the percentage of AT / GC nitrogenous bases. Plants studied showed 2n = 30 chromosomes, ranging from 4.34 -8.55 µm, with the karyotype formulae (KF) = 10m + 5sm. Through FISH, one 45S rDNA signal was observed proximally to centromere of the chromosome 7, while for 5S rDNA sites we observed one signal proximally to centromere of chromosome 9. The 2C DNA content estimated for the species was 2C = 24.4 with 59% of AT and 41% of GC. Our data allowed important upgrade for biology and cytotaxonomy of Agapanthus africanus (L.) Hoffmanns.

876. Agapanthus Campanulatus

“…In a recent study on Agapanthus africanus in cultivation at three sites in Brazil, Reis et al . () reported a DNA content of 24.4 pg for the species, bringing it close to the value for A. coddii (24.05 pg) and 7.6 pg lower than that for A. africanus (31.16 pg) obtained by Zonneveld & Duncan (). Reis et al .…”

“…Reis et al . () surmised that their observation showed great intraspecific variation in the genus. It is most likely that the samples they used in the study were from hybrid plants of A. praecox (traded as A. africanus ) as the DNA content falls in the range (23.8–25.5 pg) reported for possible hybrids of the species by Zonneveld & Duncan ().…”