Genetic Engineering Approach to Enhance Adventitious Root Formation of Hardwood Cuttings

Vegetative propagation by cuttings is critical to the horticultural industry, particularly the ornamental and fruit sections. This article briefly reviews the traditional approaches to improve root formation, specifically with hardwood cuttings. The focus of this review has been placed on the nontraditional strategies, including infection with Agrobacterium rhizogenes and genetic engineering with rol genes, or ro/B gene alone from A. rhizogenes and iaaM gene from auxin biosynthesis genes (iaaM, iaaH) from A. tumefaciens. Recent results with these new strategies have shown great potential in enhancing adventitious root formation in difficult-to-root woody species. The future perspective in understanding adventitious rooting mechanisms and new strategies for improving rooting are also discussed.