Controlling development and growth in horticultural crops

Within the broad spectrum of developmental processes relevant to horticultural crop production, the research group "Controlling Development and Growth in Horticultural Crops" focuses on adventitious root formation, which is the basis for the vegetative propagation of many ornamental plant species.

The root development of cuttings may be impaired depending on the plant genotype and the specific production chain, which often entails cuttings being stored and transported between different climatic zones. The molecular and physiological causes for this are not sufficiently clear. Furthermore, the demand for sustainable seedling production combined with technical progress, e.g. in terms of lighting, create new challenges and opportunities in the field of propagation technology. Thus, by identifying important functional relationships between certain genes, phytohormone signalling chains and primary metabolism, we are striving to create new approaches for scientifically sound culture and chain management in horticultural seedling production, as well as the required molecular control instruments.

Using a system-oriented hypothesis model for petunia developed in preliminary work at the Leibniz Institute of Vegetable and Ornamental Crops (IGZ) (Druege and Franken 2019), the functions of candidate genes will first be investigated on the same crop by means of targeted mutations. These are generated by agrobacteria-mediated transformation with CRISPR/Cas-based constructs/vectors that initiate the mutagenesis of the respective candidate gene. The function of the candidate gene in the systemic context of the stock plant, the cutting and its environment can be identified by analyzing the root phenotype and conducting further detailed studies of the mutant in comparison to the wild type under varying environmental conditions.

The research addresses the following topics:

- function of candidate genes responsible for controlling phytohormone signalling chains and source/sink relationships in petunia hybrida
- transferability of the petunia model to other crops (currently hydrangea macrophylla)
- molecular control of the relationship between the developmental phase of the stock plant and the adventitious root formation of cuttings

It is expected that the results of our work will enable the targeted adjustment of endogenous signalling chains and control of nutrient fluxes in cuttings, which will help to prevent propagation failure and reduce the use of external resources and chemical growth regulators.