Karyotype and genome size analyses in species of Helichrysum (Asteraceae)

Narjes Azizi,Zahra Nourmohammadi,Valiollah Mozaffarian,Masoud Sheidai

doi:10.1590/0102-33062014abb3136

Abstract

Karyotype studies were performed in 18 populations of eight Helichrysum species in Iran. Those species showed chromosome numbers of 2n = 2x = 14; 2n = 4x = 24, 28 and 32; 2n = 6x = 36; 2n = 7x = 42; 2n = 8x = 48; 2n = 9x = 54; and 2n = 10x = 60. The chromosome numbers of H. davisianum, H. globiferum, H. leucocephalum and H. oocephalum are reported here for the first time. New ploidy levels are reported for H. oligocephalum (2n = 4x = 24) and H. plicatum (2n = 4x = 32). The chromosomes were metacentric and submetacentric. An ANOVA among H. globiferum and H. leucocephalum populations showed significant differences for the coefficient of variation for chromosome size, total form percentage and the asymmetry indices, indicating that changes in the chromosome structure of Helichrysum species occurred during their diversification. Significant positive correlations among the species and populations studied, in terms of the total chromosome length, lengths of the short arms and lengths of the long arms, indicate that these karyotypic features change simultaneously during speciation events. The genome sizes of Helichrysum species are reported here for first time. The 2C DNA content ranged from 8.13 pg (in H. rubicundum) to 18.4 pg (in H. leucocephalum and H. davisianum). We found that C-value correlated significantly with ploidy level, total chromosome length, lengths of the long arms and lengths of the short arms (p<0.05), indicating that changes in chromosome structure are accompanied by changes in DNA content.

Highlights

The genus Helichrysum Mill. (Asteraceae, Gnaphalieae) comprises 500-600 species distributed throughout the African continent and Madagascar (Hilliard 1983; Anderberg 1991; Bayer et al 2007), as well as 41 species distributed across the Mediterranean basin, Macaronesia, central Asia and western Asia (Anderberg 1991)
Chromosome numbers were determined in 18 populations of eight Helichrysum species occurring in Iran (Tab. 1): H. davisianum Rech. f.; H. globiferum DC.; H. leucocephalum Boiss.; H. oligocephalum Boiss.; H. oocephalum Boiss.; H. armenium DC.; H. plicatum DC.; and H .rubicundum DC
Details of the karyotype analyses in Helichrysum Mill. species are presented in Tab. 1, as well as in Fig. 1 and 2

Summary

Introduction

The genus Helichrysum Mill. (Asteraceae, Gnaphalieae) comprises 500-600 species distributed throughout the African continent and Madagascar (Hilliard 1983; Anderberg 1991; Bayer et al 2007), as well as 41 species distributed across the Mediterranean basin, Macaronesia, central Asia and western Asia (Anderberg 1991). (Asteraceae, Gnaphalieae) comprises 500-600 species distributed throughout the African continent and Madagascar (Hilliard 1983; Anderberg 1991; Bayer et al 2007), as well as 41 species distributed across the Mediterranean basin, Macaronesia, central Asia and western Asia (Anderberg 1991). The Mediterranean, European, western Asian and central Asian Helichrysum species have been classified into two main groups, which in the latest treatments (Clapham 1976) are recognized at the sectional level: sect. Helichrysum are shrubs, subshrubs or herbaceous perennials, with capitula in terminal corymbose synflorescences, bearing phyllaries that are yellow or (in rare instances) white, nearly equaling the florets in length, whereas species in the sect. Suffruticose perennials, with capitula solitary or in terminal oligocephalous corymbose synflorescences, with white phyllaries extending beyond the florets (Galbany et al 2006)

Methods

Results

Conclusion