Hormone profiling of chrysanthemum hairy roots after co-cultivation with Rhizobium rhizogenes

We have used chrysanthemum as a model crop to determine auxin and cytokinin levels in hairy roots formed after coculture of leaf discs with Rhizobium rhizogenes. All 6 genotypes tested formed hairy roots, upon which the presence of T-DNA genes was tested with a qPCR assay, evaluating the presence of T_L– as well as T_R-genes.
Transformation efficiencies varied between 14 and 100%, and for every cultivar, roots with either only T_L-genes and roots with both T_L– and T_R-genes were found. 2-isopentenyladening (2iP) and indole-3-acetic acid (IAA) levels were compared for all 12 roots that yielded sufficient material for analysis.
In two cultivars, multiple T_L+T_R positive independent root lines could be compared, showing a significant difference for as well auxin as cytokinin levels.
However, both for 2iP and IAA, 10-fold differences were detected between roots induced on leaves of a single cultivar.
This suggests that phytohormone levels, and probably subsequent hairy root regeneration, depend on individual pRi-gene integration for each separate hairy root.

XXVII International EUCARPIA Symposium Section Ornamentals: From Nature to Culture – Breeding Ornamentals for Sustainability

E. De Keyser, J. Tyburski, J. Kesy, N. Mucha, T. Eeckhaut, E. Dhooghe

auxins, chrysanthemum, cytokinins, LC-MS/MS, regeneration, Rhizobium rhizogenes

https://doi.org/10.17660/ActaHortic.2023.1383.25