Regulatory Pathways of the Maturation-Related Decline in Adventitious Root Formation in Forest Tree Species

Vegetative propagation is widely used in forest plantations to propagate elite genotypes with traits of economic or ecological interest. However, the loss of the ability to form adventitious roots is a dramatic effect of tree age and maturation and represents a major limitation for the clonal propagation of high-quality genotypes. This review describes the evolution of our understanding—from the traditional role of plant growth regulators to current findings on cellular signaling—regarding the maturation-related decline of adventitious rooting in forest species. Evidence suggests that interactions between the cell wall, plasma membrane, and cytoskeleton play a key role in this process. Specific and dynamic modifications of the interactions between the cell wall and cytoskeleton could be possible targets for hormonal, developmental, environmental, and epigenetic regulation associated with the maturation-related decline in adventitious root formation.