Molecular Plant Breeding 2024, Vol.15, No.4, 178-186 http://genbreedpublisher.com/index.php/mpb 181 Figure 2 Effects of OsSAPon cellular antioxidants and reactive oxygen species (ROS) levels in Ilmi, GeD, and OsSAP-T6 lines under normal and drought conditions (Adopted from Park et al., 2022) Image caption: under drought conditions, the effects of OsSAP on the level of endogenous hydrogen peroxide (H2O2), the accumulation of malondialdehyde (MDA), the accumulation of proline (proline), the activity of superoxide dismutase (SOD), the activity of peroxidase (POD), and the activity of catalase (CAT). Data presented are expressed as mean ± SD from five independent biological experiments per line. Bars represent means ± SE. Means denoted by the same letter are not significantly different (p < 0.05) as evaluated by Duncan’s multiple range test. The GeD lines showed reduced drought tolerance, whereas the OsSAP-T6 lines showed increased drought tolerance before drought stress, and 20 days after germination. Drought stress treatment; phenotypic changes at 20% soil moisture content. Phenotypes after 7 days of recovery achieved by watering (recovery from 20% soil moisture content). Phenotypes of 3,3-diaminobenzidine (DAB) and nitro blue tetrazolium (NBT) staining when the soil moisture content was 20%. After drought stress treatment, H2O2 was visualized as brown spots by DAB, and O2 ⁻ as blue spots by NBT. The picture presented is the most representative of five independent biological experiments per each line. I: Ilmi. G: GeD0 1–1. T: OsSAP-T6. Different letters on columns represent significant (p < 0.05) difference between rice lines based on Duncan’s test (Adopted from Park et al., 2022) 3.3 Case studies of yield improvement in rice Several case studies have highlighted the successful application of CRISPR/Cas9 in improving rice yield. One notable example is the editing of the GS3 gene, which resulted in rice mutants with a 31.39% increase in grain length and a 27.15% increase in 1 000-grain weight compared to wild-type plants. This study demonstrated the effectiveness of CRISPR/Cas9 in creating high-yielding rice varieties through precise genetic modifications (Usman et al., 2021). Another case study involved the editing of multiple genes, including OsPIN5b, GS3, and OsMYB30, to produce rice mutants with both high yield and improved cold tolerance. The resulting transgenic lines exhibited significant improvements in yield-related traits and stress resistance, showcasing the potential of CRISPR/Cas9 for comprehensive agronomic trait enhancement (Zeng et al., 2020). These case studies underscore the transformative impact of CRISPR/Cas9 technology on rice breeding and its role in addressing global food security challenges.
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