Taxonomy and molecular phylogeny of natural and artificial wheat species

Abstract

The effective use of wheat biodiversity in breeding programs is dependent on a sound conservation strategy for sources of biodiversity, and on appropriate techniques of incorporation into modern cultivars. Producing artificial wheat amphiploids using genomes of related species is an effective way to increase the available gene pool. However, artificial amphiploids should be given botanic names and positions within genus Triticum classification to ensure effective collection and preservation in gene banks. In this review, an attempt to integrate the results of molecular-genetic analyses of natural and artificial wheats with their taxonomy has been made. The correspondence of earlier evolutionary and taxonomic specifications to phylogenetic relationships within Triticum has been estimated using chloroplast and nuclear DNA sequence data. The results indicated close relationships between all artificial and natural species. Based on the data, all wild and cultivated diploid wheat species were united in a separate section, Monococcon. Different variants of nuclear Acc-1, Pgk-1, and Vrn-1 genes have been detected in diploid A genome species. Detailed analysis of the genes showed that one of these variants was a progenitor for all A genomes of polyploid wheats except for that in Triticum zhukovskyi and some of the artificial amphiploids.

Molecular markers based on LTR retrotransposons BARE-1 and Jeli uncover different strata of evolutionary relationships in diploid wheats

“…We can speculate that speciation-associated amplification of mobile genetic elements coupled with evolutionary bottlenecks in the history of T. urartu and T. boeoticum could have led to fixation of multiple 'presence' alleles for novel retrotransposon insertions, which is why the proportion of species-specific SSAP markers is relatively high compared to the other marker types Kilian et al 2007;Yamane and Kawahara 2005). Interestingly, despite the recent efforts to investigate diploid wheat diversity, the problem of finding reliable diagnostic markers for A u and A b genomes has not been paid much attention, either due to lack of speciesspecific polymorphic states or because it was not among the aims of a study Goncharov et al 2009;Heun et al 2008;Kilian et al 2007;Sasanuma et al 2002). The analysis of inheritance of morphological traits also failed to identify a species-specific character for the two wild diploid wheat species apart from the hairy leaf blade type (Dorofeev et al 1979;Filatenko et al 2002).…”

Application of the ITS2 region for barcoding plants of the genus Triticum L. and Aegilops L.

“…Moreover, T. monococcum which is very closely related to T. boeticum has one informative site at 395 (C). In support to this no obvious differences in elementary genomes of T. boeoticum and T. monococcum were found based on nuclear gene variability (Goncharov et al 2009) To identify the effect of the primary sequence divergences, secondary structures were constructed (Fig. S2).…”

Taxonomic remarks on Triticum L. and ×Triticosecale Wittm.

“…the presence of morphological items (Buerkert et al 2006), have been provided. For these and other reasons, the use of the detailed system has been promoted (Heun et al 1997;Goncharov et al 2009;Knüpffer 2010). We also support the use of the diagnostic and formal system, which provides the possibility for a stable classification and a better monitoring of the numerous accessions in genebanks and on farm projects for plant genetic resources.…”

“…Some examples of names created for induced autopolyploids or artificially produced alloploids, morphologically often not distinct, are mentioned (cp. Goncharov 2002;Goncharov et al 2009). T. dicoccon Schrank, Baier.…”