Chromosome Numbers in the Meliaceae

Abstract

Summary A detailed chromosome study has been made of 58 species in 30 genera of the tropical family Meliaceae. The results largely confirm observations, by other investigators on similar tropical woody groups, that high chromosome numbers are common and that polyploidy is a frequent phenomenon. Although the chromosomes are, in most species, very small and metacentric, some differences in chromosome size and shape are detectable. Many genera seem to have a high base number and/or several different numbers. The Meliaceae, unlike some other tropical woody groups, are particularly interesting because of the considerable range of chromosome numbers they exhibit. Differences in number have been observed between even closely related species in the economically important timber genera Swietenia, Cedrela and Toona, and this has an obvious bearing on future tree breeding and tree improvement studies. The taxonomic significance of chromosome numbers is discussed.

Chromosome studies on Brazilian cerrado plants

“…270 (Forni-Martins et al, 1995) or 2n = 276 (Oliveira et al, 1992) in Eriotheca pubescens, typical of the cerrado. b) Meliaceae has very few species in the cerrado (Castro et al, 1999) and many species in forests, but several species have high chromosome numbers (Styles and Vosa, 1971;Pennington and Styles, 1975). Forni-Martins, E.R.…”

Molecular phylogenetics of Meliaceae (Sapindales) based on nuclear and plastid DNA sequences

“…Unlike some other tropical woody groups, Meliaceae also exhibit a considerable range of chromosome numbers (Styles and Vosa, 1971;review in Styles and Bennett, 1992). A base number of n ϭ 14 or multiples such as 28, 42, or even higher ploidy represent, according to Khosla and Styles (1975), the vestiges of an archaic stock of n ϭ 7, which has been considered by many workers in the field as one of the original base numbers of angiosperms (Stebbins, 1971).…”

“…Differences in number have been observed between even putatively closely related species, e.g., within Swietenia, Cedrela, and Toona. At the subfamilial and tribal levels, chromosome numbers would appear to have no obvious pattern (Styles and Vosa, 1971). Polyploid series are by no means a rare phenomenon in the group, being apparent in Aphanamixis, Aglaia, Chisocheton, Dysoxylum, and Swietenia, for example, including the occurrence of intraspecific chromosome races in some genera (Khosla and Styles, 1975;Mabberley, et al, 1995).…”

The taxonomy, chorology and reproductive biology of southern Afri­can Meliaceae and Ptaeroxylaceae

“…Chromosome counts are few but a wide difference has been reported (Styles & Vosa 1971: T. dregeana: 2n = ±360; T. emetica: 2n = 50).…”