Chromosome studies in the grass subfamily Chloridoideae. II. An analysis of polyploidy

Authors: Roodt, Rouvay; Spies, Johan J.

Source: Taxon, Volume 52, Number 4, 1 November 2003 , pp. 736-746(11)

Publisher: International Association for Plant Taxonomy

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Abstract:

Polyploidy is frequent among the grasses. This study indicates that it has a high frequency in the subfamily Chloridoideae, where more than 90% of the studied specimens are polyploids. These levels range from diploid (2n = 20 for x = 10 and 2n = 18 for x = 9) to 16-ploid (2n = 160) for x = 10 in Ctenium concinnum Nees and 20-ploid (2n = 180) for x = 9 in Hilaria mutica Benth. This polyploid trend is seen in southern Africa, as well as worldwide. Analysis indicates that many polyploids are alloploids, suggesting extensive hybridization within this group. This is supported by the presence of apomixis in many members of the subfamily. Both polyploidy and apomixis are thought to be important evolutionary mechanisms in Chloridoideae as well as closely related Panicoideae, and have a high frequency in southern Africa. Due to the stable ecological, geographical and climatological history of Africa, the continent is ideally suited for the stabilization of hybrid complexes by means of apomixis and polyploidization.

Keywords: APOMIXIS; HYBRIDIZATION; POACEAE; POLYPLOIDY; SOUTHERN AFRICA

Document Type: Research article

Affiliations: 1: Department of Plant Sciences: Genetics (62), University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa.

Publication date: 2003-11-01

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