Characterization of genomes and chromosomes in partial amphiploids of the hybrid Triticum aestivum × Thinopyrum ponticum by in situ hybridization, isozyme analysis, and RAPD

Abstract

Genomic in situ hybridization (GISH) and Southern hybridization of genome-specific RAPD markers were used to demonstrate that the E genome (including Ee and Eb from Thinopyrum elongatum and Thinopyrum bessarabicum, respectively) and the St genome (from Pseudoroegneria species) were the two basic genomes in Thinopyrum ponticum. GISH also revealed that the centromeric region may be the critical area that discriminates the St genome from the E genome in Th. ponticum. Of the seven partial amphiploids isolated from backcrossed progenies of Triticum aestivum x Thinopyrum ponticum hybrids, two (lines 693 and 7631) have eight pairs of chromosomes from the Ee and (or) Eb genomes. Four partial amphiploids (lines 784, 68, 7430, and 40767-1) have an incomplete St genome, i.e., six pairs of chromosomes of St and one pair of chromosomes from Ee or Eb. In a heptaploid individual of the partial amphiploid 40767-2, there were four pairs of St chromosomes, one pair of St/1B Robertsonian translocation chromosomes, one pair of St/E translocation chromosomes, and one pair of Ee or Eb chromosomes. The isoelectric focusing of Est-5, Est-4, β-Amy-1, α-Amy-1, and α-Amy-2 and the RAPD data generated with 24 decamer primers on five partial amphiploids (lines 784, 693, 7631, 68, and 7430) indicated that lines 693 and 7631 had identical genomes from Th. ponticum. The partial amphiploid 784 probably had a set of chromosomes completely different from those of 693 and 7631. These results indicate that genome recombination usually occurred during the formation of new polyploid lines. Key words : Thinopyrum ponticum, wheat, partial amphiploid, GISH, isozyme, RAPD.

Allopolyploids of the Genus Elymus (Triticeae, Poaceae): a Phylogenetic Perspective

“…Barkworth & D. R. Dewey, which combines the Pseudoroegneria and Hordeum genomes with the Ns genome of Psathyrostachys Nevski in an StStHHNsNsNsNs octoploid configuration (Dewey 1975), and Thinopyrum Á . Löve, some species of which are hypothesized to combine the St genome with the E and/or J genomes usually considered characteristic of Thinopyrum (e.g., Liu and Wang 1993;Zhang et al 1996;Chen et al 1998). Thus, the St genome, probably more than any other in Triticeae, plays an important role in the complex reticulate allopolyploid patterns that characterize the tribe.…”

Chromosome characterization in Thinopyrum ponticum (Triticeae, Poaceae) using in situ hybridization with different DNA sequences

“…Á. Löve, is an important source of genes for wheat, especially for leaf and stem rust resistance (McIntosh et al, 1998). Because of its decaploid nature (2n = 10x = 70) and chromosome pairing complexity, various genome formulas have been reported for this species (Muramatsu, 1990;Wang et al, 1991;Zhang et al, 1996). More recently, Chen et al (1998) Due to the importance of Th.…”

Identification of EeSt-genome species in Pseudoroegneria and Elytrigia (Poaceae: Triticeae) by using SCAR markers from ITS sequences

“…Based on chloroplast and nuclear DNA data, Mason-Gamer (2004) found a complex pattern of reticulate evolution, introgression, and intertribal gene capture in E. repens. Yu et al (2008) (Liu and Wang, 1993a,b;Xu and Conner, 1994;Zhang et al, 1996;Refoufi et al, 2001;Ellneskog-Staam et al, 2003;Yu et al, 2010). SCAR primers generated right fragments in these E e St-genome taxa, but not in St-genome and E-genome species.…”