Triticeae Genomics and Genetics, 2024, Vol.15, No.4, 173-184 http://cropscipublisher.com/index.php/tgg 176 spread from the Near East (Comadran et al., 2012). These genetic adaptations were crucial for the establishment of Triticeae crops in diverse regions, highlighting the interplay between human selection and environmental factors in the spread of these important agricultural species. 4 Genetic Adaptation to Diverse Environments 4.1 Adaptation to climate and soil The genetic adaptation of Triticeae crops to diverse climates and soils has been a key factor in their global distribution. Bread wheat, for instance, has expanded from the Fertile Crescent to various global environments over approximately 10 000 years. This expansion was facilitated by composite introgression from wild populations, which contributed significantly to the genetic diversity of bread wheat, allowing it to adapt to different climates and soils (Zhou et al., 2020). Similarly, barley has shown remarkable adaptability to different environments, with ancient landraces demonstrating exceptional tolerance to micronutrient deficiencies in marginal soils. These landraces have developed unique genetic traits over centuries, enabling them to thrive in adverse soil conditions by efficiently acquiring and translocating essential nutrients like manganese, zinc, and copper (Schmidt et al., 2018). Moreover, the genetic diversity within barley landraces from Ethiopia highlights the role of altitude in shaping genetic adaptation. Barley populations from different altitudinal gradients exhibit significant genetic variation, suggesting that selection for adaptation to varying altitudes has been a major driving force in their evolution. This local adaptation is crucial for maintaining crop productivity in diverse environmental conditions and provides a valuable genetic resource for breeding programs aimed at improving crop resilience to climate change (Hadado et al., 2010). 4.2 Resistance to pests and diseases Resistance to pests and diseases is another critical aspect of the genetic adaptation of Triticeae crops. The draft genome sequence of Aegilops tauschii, a wild relative of wheat, has revealed a rich repertoire of genes associated with disease resistance. This genetic information is invaluable for understanding the mechanisms of disease resistance in wheat and can aid in the development of more resilient wheat varieties (Jia et al., 2013). Similarly, rye, known for its wide adaptation to harsh environments, has been studied for its resistance to the fungal pathogen Pyrenophora tritici-repentis. Genome-wide association studies have identified specific genomic regions in rye that confer resistance to this pathogen, providing insights into the genetic basis of disease resistance and potential targets for breeding programs (Sidhu et al., 2019). In addition, the genetic diversity within wheat germplasm has been explored to identify genotypes with better yield stability and resistance to pests and diseases under semi-arid conditions. Field screening of diverse wheat genotypes has revealed significant variability in traits related to yield and disease resistance, highlighting the potential of certain genotypes for cultivation in challenging environments (Mahpara et al., 2022). These findings underscore the importance of genetic diversity in developing pest and disease-resistant crops, which is essential for ensuring food security in the face of changing environmental conditions. 4.3 Advances in genetic mapping Advances in genetic mapping have significantly enhanced our understanding of the genetic basis of adaptation in Triticeae crops. Whole-genome sequencing and exome sequencing have been pivotal in identifying key genetic regions associated with adaptive traits. For instance, the sequencing of bread wheat populations has revealed the role of specific genes in adaptation to different growing zones and human selection pressures, providing new perspectives on crop improvement (Zhou et al., 2020). Similarly, exome sequencing of barley has elucidated the genetic basis of adaptation by identifying genes related to key life history traits and their interactions with the environment (Figure 1). This has enabled the prioritization of genomic regions for breeding efforts aimed at developing climate-resilient barley varieties (Bustos-Korts et al., 2019). Bustos-Korts et al. (2019) conducted a gene association analysis on barley's days to heading, plant height, thousand kernel weight, and awn length using a multi-environment GWAS approach. The results revealed
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==