Molecular Relationships in Encephalartos (Zamiaceae, Cycadales) Based on Nucleotide Sequences of Nuclear ITS 1&2, Rbcl, and Genomic ISSR Fingerprinting

Abstract

The cycad genus Encephalartos is restricted to Africa and is threatened with extinction in most of its range. Total DNA was extracted from 51, i.e., 78 %, of the described species of Encephalartos. The accessions were sampled from the furthest western occurrence of the genus in Nigeria, via Sudan and Uganda, to southern South Africa. The sequences of nuclear ribosomal internal transcribed spacer regions 1 and 2 (ITS 1&2), the chloroplast encoded rbcL gene, and ISSR genomic fingerprinting were employed to resolve the molecular history and the relationships within the genus. Sequence alignment, as well as ISSR fingerprinting, data show low genetic variation among all analysed accessions, indicating diversification within the Pliocene/Pleistocene. ITS 1&2 data agree well with morphological and geographical characters and resolved three major genetic clusters with overlapping distribution ranges in eastern South Africa. This area, that contains the largest diversity of genotypes of Encephalartos, may have served as a Pliocene/Pleistocene refugium.

Geographical matching of volatile signals and pollinator olfactory responses in a cycad brood-site mutualism

“…The Porthetes sp. in this study also occurs on cones of E. aplanatus and E. umbeluziensis [51], which are phylogenetically related to [52] and out of the range of E. villosus. Encephalartos aplanatus emits the same volatile compounds as E. villosus in its northern distribution range, while E. umbeluziensis emits compounds that are different from those in any E. villosus populations [63].…”

“…It is also possible that E. villosus consists of two geographically separate species. Few molecular data are available for Encephalartos due to notoriously low genetic variation within the genus [52], and among cycads in general [53,54].…”

Molecular markers for plant species identification and phylogenetics

“…ISSR-маркеры совместно с комплексом мар-керов ДНК-штрихкодирования использовали для ре-конструкции филогенетических отношений в пределах рода Encephalartos сем. Cycadaceae (Treutlein et al, 2005), а также для целого ряда родов в пределах сем Asphodelaceae (subfamily Alooideae) (Treutlein et al, 2003а, б).…”

Taxonomic notes on Encephalartos ferox (Cycadales: Zamiaceae), with the description of a new subspecies from Mozambique

“…Treutlein et al's (2005) molecular analysis of nuclear ITS positioned two replicates as unresolved (but monophyletic 92BP) in a clade of southern African species. Their morphological analysis grouped it with E. gratus Prain (1916: 181) (the only other species with red strobili) with weak support (59BP) (Treutlein et al 2005). Rousseau (2012), using three plastid and one nuclear region, found numerous samples to group monophyletically with high support (93BP/1.0PP), though the backbone remains unresolved and as such the closest relative remains speculative-possibly an eastern seaboard South African subterranean-stemmed species (see: Rousseau 2012; Rousseau unpublished data).…”

“…An over-appreciation at the specific level as espoused by Dyer (1965a) and Vorster (2004), is due to their reluctance to recognise infraspecifc ranks, as robust phylogenies-revealing affinities-had yet to be constructed. Even molecular phylogenies remain unsettled (Van der Bank et al 1998, Treutlein et al 2005, Nagalingum 2011, though the latest efforts (Rousseau 2012) have resolved species groupings (2-7 taxa) with adequate support. Hitherto taxonomic work on Encephalartos based solely on herbarium material has yielded less than ideal results, as such material lacks characters only discernible in living specimens (e.g.…”