MPB_2024v15n5

Molecular Plant Breeding 2024, Vol.15, No.5, 269-281 http://genbreedpublisher.com/index.php/mpb 275 8.2 Breeding for resistance to abiotic stresses such as drought and salinity Abiotic stresses, including drought and salinity, pose significant challenges to sugarcane cultivation. Recent advances in breeding and genomic approaches have been instrumental in enhancing sugarcane’s tolerance to these stresses. Techniques such as molecular marker-assisted breeding, genome editing, and the use of omics technologies have identified key genes and regulatory elements responsible for abiotic stress tolerance (Meena et al., 2020; Shabbir et al., 2021). For example, the introgression of genes from wild species has led to the development of stress-tolerant varieties, and the use of CRISPR/Cas technology has enabled precise modifications to improve drought and salinity tolerance (Meena et al., 2020). Physiological interventions, such as inducing drought hardiness and managing soil salinity, also contribute to the resilience of sugarcane to abiotic stresses (Shrivastava et al., 2017). 8.3 Case studies on successful stress-resistant sugarcane varieties Several case studies highlight the successful development of stress-resistant sugarcane varieties. One notable example is the development of transgenic sugarcane utilizing the betAgene, which imparts drought tolerance and has been commercialized for cultivation (Shrivastava et al., 2017). Another example is the creation of transgenic sugarcane lines expressing CEMB-Cry1Ac and CEMB-Cry2A genes (Figure 2), which have demonstrated complete resistance to cane borers and high tolerance to glyphosate spray in field conditions (Qamar et al., 2021). Additionally, the use of transcription factors such as WRKY, NAC, MYB, and AP2/ERF has been explored to regulate gene expression in response to abiotic and biotic stresses, providing important clues for engineering stress-tolerant cultivars (Javed et al., 2020). These advancements underscore the potential of modern breeding and biotechnological approaches in developing robust sugarcane varieties capable of withstanding various environmental stresses. By integrating these strategies, the sugarcane industry can enhance crop resilience, ensuring sustainable production in the face of increasing biotic and abiotic challenges. Figure 2 Schematic presentation of all the steps involved in genetic modification of sugarcane (Adopted from Qamar et al., 2021) Image caption: (A) Callus for Bombardment. (B) Homemade Biolistic machine. (C) Bombarded Callus after bombardment with DNA-coated tungsten particles. (D) Bombarded callus shifted on selection media with Kanamycime (50 mg/L) after 2 days. (E, F) Transformed callus regenerated on double selection (Kanamycine 50 mg/L+ Glyphosate 40 mM) media, (G, H) Regenerated sugarcane plantlets on glyphosate selection media (45 mM), shifting on shoot multiplication media with Kanamycime (50 mg/L) and glyphosate (50 mM) selections. (I) Gus Assay for transgenic plant screening (abcd). (J) Transgenic plants for rooting. (K) Shifting on rooting media without any selection drug. (L, M) Acclimatization: Transgenic sugarcane plantlets in soil pots under green house conditions (Adopted from Qamar et al., 2021)

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