Evolution of the Allopolyploid Species of the Sub-tribe Triticineae

Abstract

The chapter describes the mode, time, and place of origin of the allopolyploids of the genus Triticum. In addition, genetic and epigenetic changes due to allopolyploidization that brought about to cytological diploidization (exclusive homologous chromosome pairing), are discussed within the chapter. The suppression of pairing between homoeologous chromosomes in hexaploid wheat Triticum aestivum by the Ph1 gene, its discovery, the induction of mutations in this gene, its isolation, the theories concerning its mode of its action, and its origin, are discussed in the chapter. Other pairing genes (suppressors and promoters) that exist in T. aestivum, and in its relatives are reviewed. The chapter also describes processes leading to genetic diploidization and subgenomic asymmetry in the control of various traits in allopolyploid wheats. Several aspects of evolution during the life of the allopolyploids are discussed too.