Triticeae Genomics and Genetics, 2024, Vol.15, No.3, 125-136 http://cropscipublisher.com/index.php/tgg 126 evolutionary history, and the current status of distribution and utilization of genetic resources within the Triticeae family. Additionally, the study will explore protection strategies and utilization approaches for Triticeae genetic resources, providing scientific evidence and references for breeding improvement, genetic resource conservation, and sustainable agricultural production of Triticeae crops. This is not only significant for the research and application of Triticeae crops, but also plays an active role in promoting the progress and development of global agricultural production. 2 Taxonomy of Triticeae 2.1 Historical background and classification systems The tribe Triticeae, a significant group within the Poaceae family, has been the subject of extensive taxonomic studies due to its inclusion of major cereal crops such as wheat, barley, and rye, as well as numerous forage grasses. Historically, taxonomic treatments of Triticeae were primarily based on comparative morphology and geography. Morphological characters, which are phenotypic expressions resulting from the interaction of dominant genes and environmental factors, were the main criteria for classification. However, this approach often led to misclassifications due to morphological convergence in distantly related taxa and divergence in closely related taxa under different environmental conditions (Yen and Yang, 2009). With the emergence of cytogenetics and molecular genomic analysis, traditional classification systems have been developed, providing more accurate insights into the phylogenetic relationships within the wheat family. For example, Hyun et al. (2020) obtained single nucleotide polymorphism (SNP) markers covering all seven chromosomes from 283 wheat related genotypes using GBS technology. These SNP markers provide rich genetic information for the phylogenetic relationships between different species within the wheat genus. Based on these SNP data, researchers successfully constructed the first high-resolution phylogenetic tree of the wheat genus, providing new insights into the species classification and evolutionary relationships of the wheat genus (Figure 1). Hyun et al. (2020) demonstrated the genetic relationships of 114 Triticum species and subspecies through a Bayesian phylogenetic tree. The color-coded and labeled branches help to understand the genetic grouping and chromosomal composition among different accessions. Additionally, the Bayesian posterior probabilities provide confidence information on these genetic relationships and offer valuable insights into the genetic relationships among Triticum species and subspecies, aiding in the further understanding of their evolutionary history and genetic diversity. 2.2 Current taxonomic classification and key species The current taxonomic classification of Triticeae integrates both morphological and genomic data to provide a more comprehensive understanding of the tribe's diversity. Recent genomic investigations have recognized approximately 30 genera within the Triticeae, reflecting a more refined and accurate classification system (Yen and Yang, 2009). Key species within this tribe include the major cereal crops wheat (Triticum spp.), barley (Hordeum spp.), and rye (Secale spp.), as well as important forage grasses such as elymus and agropyron (Bothmer et al., 2008; Knüpffer, 2009). Chen et al. (2020) investigated the genetic relationships among different species and genomes in the Triticae family (Figure 2). They subdivided the Triticae family into wild-type, cultivated type, and hybrid type genomes based on the discovery that they originated from a common ancestor, and explained the genome naming method, emphasizing the differences between different genera, species, and strains within the same family, revealing the diversity of the wheat genome and its close relationship with species classification. The genomic resources available for Triticeae have significantly advanced our understanding of these species. For example, the whole genomes of barley, wheat, Tausch’s goatgrass (Aegilops tauschii), and wild einkorn wheat (Triticum urartu) have been sequenced, providing valuable data for comparative genomics and crop improvement (Mochida and Shinozaki, 2013). These genomic tools are crucial for identifying new genes and understanding the evolutionary relationships within the tribe.
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==