Phylogenetic relationships of the monogenomic species of the wheat tribe, Triticeae (Poaceae), inferred from nuclear rDNA (internal transcribed spacer) sequences

Abstract

Phylogenetic relationships of 30 diploid species of Triticeae (Poaceae) representing 19 genomes were estimated from the sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. The ITS sequence phylogeny indicated that: (i) each genome group of species is monophyletic, concordant with cytogenetic evidence; (ii) Hordeum (I) and Critesion (H) are basal; (iii) Australopyrum (W) is closely related to Agropyron (P); (iv) Peridictyon (G), Heteranthelium (Q), and Dasypyrum (V) are closely related to Pseudoroegneria (S); (v) most of the annuals, Triticum s.l. (A, B, D), Crithopsis (K), Taeniatherum (T), Eremopyrum (F), Henrardia (O), Secale (R), and two perennials, Thinopyrum (J) and Lophopyrum (E), all of Mediterranean origin, are a monophyletic group. However, phylogenetic trees based on morphology group these Mediteranean species with various perennial lineages of the Arctic-temperate region. The molecular data and biogeography of the tribe suggest that the Mediterranean lineage is derived from the Arctic-temperate lineage and that the two lineages have evolved in parallel. Extensive morphological parallelism apparently obscures the true genealogical history of the tribe when only morphology is considered.

Phylogenetic relationships of species in Pseudoroegneria (Poaceae: Triticeae) and related genera inferred from nuclear rDNA ITS (internal transcribed spacer) sequences

“…The amplification of ITS regions was done using primers ITS-4 (5'-TCCTCCGCTTATTGATATGC-3') and ITS-L (5'-TCGTAACAAGGTTTCCGTAGGTG-3') (Baldwin 1992;Hsiao et al 1995). The PCR reaction was carried out in a total volume of 25 µL containing 1× reaction buffer, 1.5 mM MgCl2, 0.5 µM of each primer, 200 µM of each dNTP (TakaRa Biotechnology Co., Ltd, Dalian, China), 0.5 units of ExTaq Polymerase (TakaRa), with an addition of 10% dimethyl sulfoxide (Buckler & Holtsford 1996;Buckler et al 1997) and sterile water to the final volume.…”

“…The boundaries of the ITS regions were determined by comparison with the ITS sequence ofPseudoroegneria libanotica (Hackel) D. R. Dewey (GenBank accession number L36501) (Hsiao et al 1995). The ITS sequence alignment was executed with Clustal X program (Thompson et al 1997).…”

Polyploidy origin of wheatgrass Douglasdeweya wangii (Triticeae, Poaceae): evidence from nuclear ribosomal DNA internal transcribed spacer and chloroplast trnL–F sequences

“…In the case of multiple identical sequences resulting from cloned PCR products from one accession, only one sequence was included in the data set. The boundaries of the ITSs (ITS1-5.8S-ITS2) and trnL-F (trnL intron-trnL 3′exon-intergenic spacer-trnF5′ exon) were determined according to Hsiao et al (1995) and Ogihara et al (2002), respectively. Gaps were coded as missing data.…”

“…They were analyzed together with 23 Pseudoroegneria taxa (St), two Agropyron taxa (P), and one accession of Hordeum bogdanii. H. bogdanii was used as an outgroup selected based on the previous phylogenetic studies of Triticeae (Hsiao et al 1995). All seed materials were kindly provided by American National Plant Germplasm System (Pullman, Washington, USA).…”

“…NrDNA ITS region was amplified by the primers of ITS4 and ITS5 (Hsiao et al 1995). The polymerase chain reaction (PCR) amplification of ITS was carried out in a total reaction volume of 25 μL containing 1× reaction buffer, 1.5 mM MgCl 2 , 0.5 μM of each primer, 200 μM of each dNTP (TaKaRa Inc., Dalian, Liaoning, China), 0.5 U of Ex Taq Polymerase (TaKaRa Inc., Dalian, Liaoning, China), with an addition of 8% dimethyl sulfoxide (DMSO) and water to the final volume.…”