Revolutionizing poplar biotechnology: Genetic transformation and CRISPR/Cas strategies

Due to the huge economic, ecological, and social benefits, poplar (Populus) is the most widely distributed woody plant species in many countries. Precision breeding of fast-growing, high-quality, and stress-resistant poplar varieties represents a critical direction for advancing both theoretical frameworks and technical innovations in poplar genetic improvement. CRISPR/Cas-mediated genome engineering, as a cornerstone of modern biotechnology, has emerged as a transformative tool to accelerate breeding cycles and enhance efficiency in forest tree improvement. However, most native species and commercially cultivated varieties still lack robust and optimized protocols for plant transformation and genome engineering. This comprehensive review synthesizes existing research to systematically categorize key methodologies and factors that determine efficiency of genetic transformation systems, including transient and stable transformation, as well as CRISPR/Cas-mediated genome engineering approaches such as genome editing, base editing, prime editing, and transcriptional regulation across diverse poplar genotypes. By providing foundational insights into optimizing the breeding efficiency of elite poplar cultivars, we highlight emerging opportunities for precise genetic modifications in this ecologically and economically vital perennial tree species, as well as other recalcitrant woody species.