A Review of Genome Sequencing in the Largest Cereal Genome, <i>Triticum aestivum</i> L.

Abstract

Sequencing whole plant genomes has advanced rapidly with the development of next generation sequencing (NGS) technologies and bioinformatics, enabling the study of large and complex genomes such as that of the hexaploid cereal, Triticum aestivum L. (bread wheat). Despite advances, however, confounding factors such as repetitive elements and low polymorphism still hinder sequencing attempts. Isolation techniques such as sequencing of diploid progenitors and chromosome separation through flow cytometry have showed promise in reducing the size of the genome for sequencing. In this review we discuss the advances and stumbling blocks that have been encountered on the road toward the complete hexaploid wheat genome sequence. We also discuss the latest complimentary techniques and the progression of accumulation of sequence data relevant to wheat genome research.

Wheat chromatin architecture is organized in genome territories and transcription factories

“…Despite a considerable degree of synteny among subgenomes due to the phylogenetic relatedness of the three progenitors [30], wheat chromosomes form meiotic pairs only with the respective homolog and never with their homeologs [62]. This mechanism prevents the independent segregation of chromosomes from different genomes and results in disomic inheritance.…”

“…A second hybridization event between T. turgidum (AABB) and the diploid species Aegilops tauschii (DD genome) gave rise to a hexaploid wheat (AABBDD), the ancestor of the modern bread wheat, about 10,000 years ago [25,29]. Since the three ancestors are closely related species descended from a common progenitor, three distinct but highly syntenic subgenomes can be identified (AA, BB, and DD) [30]. Compared to tetraploid wheat, modern hexaploid wheat possesses several agricultural advantages, such as increased environmental adaptability, tolerance to abiotic stresses (including salinity, acid pH, and cold), and increased resistance to several pathogens, factors that contribute to its success as a crop [31].…”