Bioscience Evidence 2024, Vol.14, No.1, 32-38 http://bioscipublisher.com/index.php/be 35 Figure 1 Cas9/gRNA Agrobacterium-mediated cassava transformation and recovery of transgenic cassava plants (Adopted from Veley et al., 2023) Note: A Left: Example of CBB-infected cassava in a field. Right: selected region from leaf on the left. Water-soaked regions are indicated with white arrows. B Graphical representation of epigenetic CBB disease resistance strategy. Top: In WT plants, TAL20 from Xam binds a specific sequence (EBE) present in the promoter of the S gene MeSWEET10a. Upon binding, TAL20 induces the ectopic expression of MeSWEET10a, a sugar transporter, which is required for establishment of disease. A typical ‘water-soaked’ lesion is shown to the right, an early indicator of CBB. Bottom: DNA methylation prevents TAL20 from binding the EBE. MeSWEET10a expression is not induced, and disease symptoms are reduced. Source data are provided as a Source Data file (Adopted from Veley et al., 2023) 3.2 Improving nutritional quality Improving the nutritional quality of cassava, particularly its provitamin A carotenoid content, is another area where genomic tools have been effectively employed. Genomic selection (GS) has been tested for its effectiveness in rapidly improving cassava for total carotenoids content, with promising results indicating that GS can be a useful tool for genetic improvement in this aspect (Esuma et al., 2021). The identification of quantitative trait loci (QTL) associated with carotenoids content has also been facilitated by genomic approaches, which can lead to the development of cassava varieties with enhanced nutritional profiles (Yonis et al., 2019). 3.3 Case studies: successful improvement projects and practical application of technology The next-generation cassava breeding project, led by Cornell University and implemented in collaboration with IITA and the National Root Crop Research Institute (NRCRI) of Nigeria, is an exemplary international cooperation project. This project has innovatively accelerated the breeding process of cassava by utilizing genome selection and genotyping techniques. By accurately identifying genetic markers that control key traits such as high yield and disease resistance, researchers are able to efficiently screen plants with excellent characteristics, greatly shortening the multi-year field trial cycle required in traditional breeding. This technological innovation has successfully nurtured five high-yield and disease resistant new varieties, including "Game Changer", "Hope", "Obasanjo 2", "Baba 70", and "Poundable". These varieties not only have high yields and strong adaptability, but also have been customized according to the preferences of local consumers, indicating that their promotion in Nigeria and even the entire African region will have a profound impact on improving food security levels and promoting income growth for farmers (Improving Crops, 2023, https://annualreport.iita.org/2023/03/27/molecular-breeding-comes-of-age-in-cassava-improvement/). IITA's molecular breeding program further deepens the application of genomics in cassava improvement. This plan provides a strong foundation for precise localization of genes related to key agronomic traits by constructing high-quality reference genomes and haplotype maps (Divya et al., 2024). Specifically, the project team identified specific chromosomal regions associated with cassava mosaic disease resistance and reduced tuber blueing (an
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