CRISPR-Cas Genome Editing for Climate-Smart Agriculture: Molecular Tools, Stress Resilience, and Regulatory Horizons

Abstract

Global agriculture faces an unprecedented convergence of population growth and climate change, demanding a 25-60% increase in food production by 2050 while contending with rising temperatures, drought, salinity, and emerging phytopathogens. Conventional breeding and transgenesis have proven insufficient to meet these challenges due to genetic bottlenecks, lengthy timelines, and regulatory constraints. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas) systems have revolutionized plant biotechnology by enabling precise, targeted genome modifications directly within elite germplasm. This comprehensive review examines the molecular mechanics of CRISPR-Cas platforms, including SpCas9, Cas12a, base editing, prime editing, and epigenome editing, highlighting their applications in developing climate-resilient and high-yielding crop varieties. Key achievements include promoter engineering of maize ARGOS8 that increased drought tolerance yields by 5 bushels per acre, susceptibility gene knockouts conferring resistance to powdery mildew, bacterial blight, and citrus canker, and multiplex editing enabling synthetic apomixis for hybrid vigor fixation. The review critically evaluates global regulatory frameworks, contrasting product-based models (United States, Brazil, Japan) with process-based approaches (European Union), and examines recent policy shifts toward exempting transgene-free edits from GMO oversight. Despite technical bottlenecks including tissue culture recalcitrance, off-target mutations, and complex polygenic trait engineering, emerging solutions such as morphogenic regulators, high-fidelity Cas variants, and integration with pangenomics and speed breeding promise to accelerate crop improvement. CRISPR-Cas technology represents a transformative paradigm for developing climate-smart agriculture, offering precise, efficient, and transgene-free pathways to enhance food security in an era of environmental uncertainty.