Genomics and Applied Biology 2024, Vol.15, No.1, 47-53 http://bioscipublisher.com/index.php/gab 49 2.3 The role and importance of genetic mechanisms in cassava disease resistance The genetic mechanisms underlying disease resistance in cassava are crucial for the development of resistant varieties. Traditional breeding methods have been somewhat limited due to cassava's high heterozygosity and the separation of traits during breeding. However, genetic transformation and modern breeding techniques, such as CRISPR/Cas9, offer promising avenues for enhancing disease resistance in cassava. CRISPR/Cas9, in particular, allows for precise modifications of the cassava genome, potentially enabling the development of transgene-free, disease-resistant crops. This is a significant step forward in ensuring sustainable agricultural production and food security, as it accelerates resistance breeding and overcomes the limitations of conventional breeding (Li et al., 2021). The application of these genetic tools in breeding programs is expected to improve the resistance of cassava to various diseases, thereby contributing to the stability of food systems in regions where cassava is a critical crop (Mehta et al., 2019). 3 Introduction and Application of CRISPR/Cas Technology 3.1 Principles and operational steps of CRISPR/Cas technology CRISPR/Cas technology is a revolutionary genome-editing tool that has transformed the field of genetics. The system originates from a natural defense mechanism found in bacteria and archaea, where it provides acquired resistance against viruses by targeting and cleaving their DNA (Tang et al., 2023). The CRISPR/Cas system is composed of two key components: the Cas9 enzyme, which acts as a molecular scissor, and a guide RNA (gRNA) that directs the Cas9 to a specific DNA sequence. The operational steps involve designing a gRNA that matches the target gene sequence, delivering the Cas9-gRNA complex into the organism's cells, and then relying on the cell's own repair mechanisms to introduce mutations or replace the gene sequence after the DNA is cut (Figure 1) (Tao et al., 2022). Figure 1 The working mechanism of the CRISPR/Cas system (Tao et al., 2022) 3.2 Application examples of CRISPR/Cas technology in cassava disease resistance The application of CRISPR/Cas9 gene editing technology in cassava, an important tropical food crop, has opened up a new way for crop genetic improvement and enhanced disease resistance. By precisely modifying the genetic code of cassava, scientists are exploring how to use this revolutionary technology to combat various diseases that have long plagued cassava cultivation, such as those caused by viruses, fungi, and bacteria, which severely limit cassava yield and quality.
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