The Never-Ending Story of the Phylogeny and Taxonomy of Genus Triticum L.

Resumo

The aim of many breeding programs for the conservation of genetic biodiversity is to preserve the genetic resources of wild species of wheat. Long-term selection combined with genetic drift (random changes in allele frequency within a population) and the bottleneck effect (a sudden random event that decreases the size of a population and limits its gene pool) have depleted the genetic diversity of the most popular species of the genus Triticum:common wheat (T. aestivum ssp. aestivum) and durum wheat (T. turgidum ssp. durum). These changes have turned the researchers’ attention to ancient species of wheat, including einkorn (T. monococcum ssp. monococcum), emmer (T. turgidum ssp. dicoccum) and spelt (T. aestivum ssp. spelta). Ancient species are characterized by a rich gene pool, and the most desirable genes can be transferred to the cultivated wheat species via introgression. Advanced molecular techniques support increasingly complex analyses of genetic diversity in various accessions of the genus Triticum and detailed examinations of their relationship, which determines changes in the taxonomy of the genus Triticum. Genetic diversity analyses increasingly often rely on DNA markers with various sensitivity, mostly restriction fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP), simple sequence repeat (SSR), single-nucleotide polymorphism (SNP) and diversity arrays technology (DArT) markers. The development of a universal taxonomic system for the genus Triticum is a highly challenging task. Continued efforts are being made in this area to expand our knowledge about the phylogeny of wheat and systematize various accessions in genetic databases.