About this Research Topic
The neoformation of adventitious roots (AR) is a key step in the success of plant vegetative propagation, which is used extensively in the dissemination of elite genotypes with application in agricultural, horticultural, and forestry systems, and usually selected from conventional or molecular breeding programs. The development of de novo roots in cuttings depends on the capacity of differentiated tissue cells to reprogram efficiently and acquire a new evolutionary pattern, like that of meristematic cells, allowing subsequent differentiation of a different organ. This biological process, which ends with a morphogenic response, is under the control of a complex network of signaling, metabolic, and transport pathways.
Focused on the improvement of adventitious rooting efficiency, different plant propagation protocols have been developed. Protocols are mainly attempt/error approaches, which are adjusted to each plant genotype or propagation method binomial, depending on whether hardwood, semi-hardwood, or softwood cuttings are used. However, these adjustments made by empirical approaches are not always easy, and in some specific cases, it was impossible to overcome the recalcitrant behavior of some genotypes regarding adventitious root formation. This led nurseries to simply replace some recalcitrant genotypes with others that, albeit more efficient in the development of AR, do not always present similar agronomical interest.
High-throughput platforms focused on different omics, and new information on the distinct roles and interactions of certain molecular, hormonal, and metabolic factors, has improved the understanding of the functional equilibrium of the whole cutting in a complex environment, and, therefore, provided new information on the mechanisms underlying AR formation. Nevertheless, despite the progress that has been made, the process is far from being fully understood, especially in genotypes showing a recalcitrant behavior.
This Research Topic intends to provide additional insight into the molecular, biochemical, and physiological basis of adventitious root formation. Both fundamental and applied research are encouraged, which could contribute to the understanding of the biological mechanisms involved in AR, from signaling to morphogenesis. We welcome the submission of Original Research, Reviews, Opinions, and Perspectives, bringing novel insights into the understanding of the biological mechanisms underlying the development of adventitious roots.
The following sub-topics are considered:
• Histological studies revealing anatomical barriers to the development of adventitious roots, which could justify the recalcitrant behavior of some genotypes.
• Auxin biosynthesis, perception, signaling and polar transport (including influx/efflux).
• Involvement of different signaling pathways during the adventitious rooting process – the role of ROS, wound-related hormones and other plant growth regulating molecules.
• Enzymatic system responsible for generation and scavenging of reactive oxygen species (proteins belonging to the antioxidant system, e.g. superoxide dismutase, ascorbate-glutathione cycle, glutathione peroxidases).
• The role of mitochondria on adventitious rooting efficiency – nuclear genes encoding mitochondrial proteins with a key function.
• Nutritional and metabolic control of adventitious root formation – identification of metabolites that could be used as biomarkers of adventitious rooting ability.
• Adventitious rooting as an agronomical trait controlled by epigenetic events (e.g. DNA methylation, histone modifications, miRNAs).
• Functional polymorphisms identified at genome level underlying recalcitrant behavior upon adventitious rooting stimulus (SNPs, InDels, transposable elements).
• Integrative view of data generated by different omics following a high throughput approach.
Keywords: Vegetative propagation, Dedifferentiation, Auxin signaling, Transport and metabolism, Abiotic stress response, Differential expressed genes (DEGs)
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.