Karyotypic features including organizations of the 5S, 45S rDNA loci and telomeres of Scadoxus multiflorus (Amaryllidaceae).

Arunrat Chaveerach,Pansa Monkheang,Runglawan Sudmoon,Tawatchai Tanee

doi:10.3897/compcytogen.v10i4.9958

Abstract

Scadoxus multiflorus Martyn, 1795 is an ornamental plant with brilliantly colored flowers. Even though its chromosomes are rather large, there is no karyotype description reported so far. Therefore, conventional and molecular cytogenetic studies including fluorescence in situ hybridization (FISH) with 45S and 5S rDNA, and human telomere sequence (TTAGGG)n probes (Arabidopsis-type telomere probes yielded negative results) were carried out. The chromosome number is as reported previously, 2n = 18. The nine chromosome pairs include two large submetacentric, five large acrocentric, one medium acrocentric, two small metacentric and eight small submetacentric chromosomes. Hybridization sites of the 45S rDNA signals were on the short arm ends of chromosomes #1, #3 and #8, while 5S rDNA signals appeared on the long arm of chromosome 3, in one homologue as a double signal. The telomere signals were restricted to all chromosome ends. Three chromosome pairs could be newly identified, chromosome pair 3 by 5S rDNA and chromosomes #1, #3 and #8 by 45S rDNA loci. In addition to new information about rDNA locations we show that the ends of Scadoxus multiflorus chromosomes harbor human instead of Arabidopsis-type telomere sequences. Overall, the Scadoxus multiflorus karyotype presents chromosomal heteromorphy concerning size, shape and 45S and 5S rDNA positioning. As Scadoxus Rafinesque, 1838 and related species are poorly studied on chromosomal level the here presented data is important for better understanding of evolution in Amaryllidaceae.

Highlights

Scadoxus multiflorus Martyn, 1795 is a species belonging to the family Amaryllidaceae (Chase et al 2009), which can naturally only be found in Southern and tropical Africa (Patwary and Zaman 1980)
The idiogram and karyotype analyses established from the metaphases confirmed the diploid chromosome number of S. multiflorus to be 2n = 18
The 5S rDNA signals were detected on the long arms of chromosome #3 with one homologue showing two adjacent signals (Figs. 3B–C)

Summary

Introduction

Scadoxus multiflorus Martyn, 1795 ( known as Haemanthus multiflorus Martyn, 1795 and H. kalbreyeri Baker, 1878) is a species belonging to the family Amaryllidaceae (Chase et al 2009), which can naturally only be found in Southern and tropical Africa (Patwary and Zaman 1980). Both studies reported 2n = 18 chromosomes, Ahirwar and Verma (2014) found six submetacentric and 12 acrocentric chromosomes while Patwary and Zaman (1980) reported one metacentric, nine submetacentric, six acrocentric and two telocentric chromosomes Besides these contradictory data, molecular cytogenetic approaches like florescence in situ hybridization (FISH) have not been applied in this species yet. Such methods being available since the late 1980s (Li et al 2016, Taguchi et al 2016) enable detection, characterization and localization of rDNA regions (Chirino et al 2015) and/or telomeres The latter are known to be important to protect chromosomal ends of all eukaryotes against nucleolytic degradation, non-homologous end-joining and replication-mediated shortening. In some plants the TTTAGGG-type telomere repeat is lacking and substituted by other repeat sequences (Fajkus et al 2016)

Methods

Results

Conclusion