Phylogenetic relationships of Salix (Salicaceae) based on rbcL sequence data

Abstract

Nucleotide sequences of the chloroplast-encoded rbcL gene were used to examine phylogenetic relationships of the genus Salix together with other allied genera of the family Salicaceae. Phylogenetic analyses of rbcL sequences strongly suggest the monophyly of three commonly recognized genera (Chosenia, Salix, and Toisusu). Two monophyletic groups are recognized within the larger monophyletic group. They do not correspond with any infrageneric taxa proposed so far. With regard to character evolution, it is thought that the reduction of stamen number from more than two stamens to two might occur in at least three lineages and that fused bud scales evolved several times and/or the reverse evolution occurred from fused to free. Some types of pollen surfaces are considered to have evolved independently.

Phylogenetic Analysis of the Far Eastern Salix (Salicaceae) Based on Sequence Data from Chloroplast DNA Regions and ITS of Nuclear Ribosomal DNA

“…The relationship between these sections was confirmed using the analysis based on rbcL sequencing (Azuma et al 2000, Chen et al 2010. According to the re sults of molecular studies (Azuma et al 2000, Chen et al 2010, species assigned to the subgenus Protitea (S. amygdaloides, S. gooddingii, S. hum bold tiana, S. floridana, S. tetrasperma, S. acmophylla, and S. chaenomeloides) (Ohashi 2001, Argus 2010, appear in va rious clusters or clades, attesting to its polyphyletic nature. Accor ding to Ohashi (2000Ohashi ( , 2001, Asian S. glandulosa Seemen (= S. chaenomeloides Kimura), whose genetic rela tion ships remained unresolved in our study, is the type spe cies of this subgenus.…”

“…Accor ding to Ohashi (2000Ohashi ( , 2001, Asian S. glandulosa Seemen (= S. chaenomeloides Kimura), whose genetic rela tion ships remained unresolved in our study, is the type spe cies of this subgenus. In the rbcLphylogeny (Azuma et al 2000, Chen et al 2010, the S. chaenomeloides is placed in the same cluster along the species of the subgenus Sa lix s.l., demonstrating the resemblance to the Asian S. tetrasperma (sect. Humboldtianae) and African S. mucronata Thunb.…”

“…(BP 62 %) rather than with S. arbutifolia. Based on the MPanalysis of nucleotide sequences of the cpDNA rbcL gene, Azuma et al (2000) demonstrated that species from three typically recognized genera -Chosenia, Salix and Toisusu -form a monophyletic group. Based on the results of analysis of three cpDNA markers (rbcL, trnD-trnT, atpB-rbcL), Chen et al (2010) included Chosenia in Salix at the rank of subgene ric level and proposed to subdivide the genus Salix s.l.…”

“…There are ve ry few works focused on phylogeny of Salix, among them: Leskinen & AlströmRapoport (1999), Azuma et al (2000), Chen et al (2010), , Abdollahzadeh et al (2011). It should be noted that in comparison to other groups of flowering plants the number of species belonging to this genus included in the studies is insignificant.…”

“…shi accepts the broad concept with respect to the genus Sa lix, relying on the data on pollen morphology (Sohma 1993), the results of molecular analysis (Leskinen & Alst römRapoport 1999, Azuma et al 2000, and the novel eva luation of morphological features. He divided Salix in Ja pan into six subgenera: Pleuradenia, Chosenia, Protitea, Cha maetia, Salix, and Vetrix.…”