Hormone-metabolic interactions in adventitious roots

Adventitious roots are roots that form after the plant embryo has grown. They’re the roots that can grow out of stems when you make plant cuttings. Adventitious root formation is a bottleneck for the survival of isolated plant fragments. Adventitious root formation plays an important ecological role and is a critical process in cuttings for the clonal propagation of horticultural and forestry crops. Understanding the regulation of excision-induced adventitious root formation is essential for the sustainable and efficient use of plant genetic resources.

Recent studies of plant transcriptomes, proteomes and metabolomes, and the use of mutants and transgenic lines have significantly expanded our knowledge concerning excision-induced adventitious root formation. Druege et al. integrate new findings regarding adventitious root formation in the cuttings of diverse plant species. These findings support a new system-oriented concept that the phytohormone-controlled reprogramming and differentiation of particular responsive cells in the cutting base interacts with a co-ordinated reallocation of plant resources within the whole cutting to initiate and drive excision-induced adventitious root formation.

Despite advanced research in the last decade, important questions remain open for future investigations on excision-induced adventitious root formation. These questions concern the distinct roles and interactions of certain molecular, hormonal and metabolic factors, as well as the functional equilibrium of the whole cutting in a complex environment. Starting from model plants, cell type- and phase-specific monitoring of controlling processes and modification of gene expression are promising methodologies that, however, need to be integrated into a coherent model of the whole system, before research findings can be translated to other crops.

Further reading

Druege U., Hilo A., Pérez-Pérez J.M., Klopotek Y., Acosta M., Shahinnia F., Zerche S., Frankem P., Hajirezaei M.R. (2019). Molecular and physiological control of adventitious rooting in cuttings: phytohormone action meets resource allocation. Annals of Botany, 123(6), 929-949. https://doi.org/10.1093/aob/mcy234