CRISPR-Cas9 Mediated Genome Editing for Enhancing Plant Stress Tolerance

https://doi.org/10.5281/zenodo.18168828

Abstract

Abiotic stresses, especially drought and salinity, significantly limit crop productivity and risk agricultural sustainability under changing climatic circumstances. This study employed CRISPR-Cas9-mediated genome editing to implement targeted alterations in the promoter region of a stress-responsive transcription factor gene to improve stress tolerance. Genome-edited lines showed a significant stress-inducible transcriptional response, with target gene expression rising to 2.45 ± 0.35- and 2.28 ± 0.32-fold in edited lines under stress, compared with 1.00 ± 0.16-fold in wild-type plants. Under drought stress, modified plants exhibited significantly enhanced physiological performance, characterized by elevated relative water content (68.9 ± 4.3% vs. 58.3 ± 4.8%), increased chlorophyll index (31.8 ± 2.7 vs. 24.6 ± 3.2 SPAD units), and improved photosynthetic rate (7.8 ± 1.0 vs. 5.2 ± 1.1 µmol CO₂ m⁻² s⁻¹) in comparison to wild-type plants. Drought survival post-recovery improved from 41.7 ± 10.4% in wild-type plants to 75.0 ± 9.1% in modified lines. Under salinity stress (150 mM NaCl), altered plants demonstrated enhanced survival (80.6 ± 8.7% compared to 50.0 ± 9.6%), diminished leaf Na⁺ buildup (13.7 ± 1.9 vs 19.2 ± 2.3 mg g⁻¹ DW), and a lowered Na⁺/K⁺ ratio (0.82 ± 0.12 versus 1.37 ± 0.18). Yield was consistently regulated under control circumstances and markedly enhanced under stress, with total seed mass under drought rising from 0.93 ± 0.16 g plant⁻¹ in wild-type plants to 1.26 ± 0.17 g plant⁻¹ in altered lines. The results indicate that promoter-based CRISPR-Cas9 editing significantly improves abiotic stress tolerance without compromising agronomic performance.