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5.1 Adventitious root formation and stress reaction of ornamental crops

1. Research Domain
FUNCT Functional Plant Biology
2. Research Domain
MICRO Plant-Microbe Systems
3. Research Domain
QUALITY Plant Quality and Food Security
4. Research Domain
HORTSYS Next-Generation Horticultural Systems

Roots are essential organs for the survival and growth of higher plants. In this context, plants exhibit the unique potential to generate new roots in stems or leaves after being excised form the plant. This so-called adventitious root (AR) formation reflects the outstanding plasticity and capacity of plants to acclimate to abiotic stress conditions and to regenerate. Induced by the injury and by the isolation from the plant, a new developmental program is initiated in particular cells in the excised plant part to regenerate the lost root system. However, the functional contribution to this process of activation and repression of particular genes, of plant hormones and secondary signals, and of the multifaceted responses of primary and secondary plant metabolism, are only poorly understood.

For many centuries, AR formation in cuttings has been utilized for clonal multiplication of plants generating genetically identical propagules. Modern propagation of ornamental crops by cuttings is carried out at industrial level by highly specialized companies. It involves a multistage young plant production chain starting with cutting production on stock plants at low latitude sites for example in East Africa and including subsequent storage and transport of harvested cuttings to rooting stations in Europe, where they are planted for root formation. Each year, several billons of rooted cuttings are produced to meet the demand of European citizens for flowers and other ornamentals.

The young plant producers are facing great challenges. Root formation is insufficient with certain plant species or cultivars, which impairs bringing them into the market. Knowledge gaps concerning the influence and interactions of particular environmental factors during the chain repeatedly cause losses in young plant production, also of easy to root species. Shortage in resources and the increasing demand of society for environmentally sound systems require new production technologies. On the other hand, new potentials arise from the continuous advance in technical systems, e.g. in the illumination sector. However, optimization of the young plant production chain is impaired by the lack of understanding of the control of AR formation at the different levels. This research domain aims to address and close these knowledge gaps.

One important objective is to further identify important environmental factors controlling AR formation, and furthermore, to elucidate the underlying regulative processes at molecular, metabolic and plant physiological levels. For this, cutting-edge methods and tools of molecular genetics and analytical biochemistry are combined with microscopy and pharmacological approaches and preferentially applied to Petunia as a newly developed model system for ornamentals. Based on recent findings of our group, current hypotheses address the functional contribution of nitrogen remobilization and of auxin action to AR formation as modified by nitrogen supply and cold dark storage. The same methodic platform and current concepts on the response of plant metabolism to abiotic stress are further employed to increase the understanding of genetic control of plant tolerance to mild chilling stress.

In addition to the basic research, applied approaches focus on the improvement of the horticultural practice. Here, we test the applicability of the new findings concerning the improvement of AR formation and of stress tolerance to real production conditions and to difficult to root or to stress-sensitive plant species. Within this scope, we aim to broaden the use of near-infrared-spectroscopy as a new tool for quality evaluation of cuttings and to implement this technology in the global young plant production chain.

Die Petunia Platform

Current Project

2014 - 2017

Quality assurance in the production of ornamental cuttings

The quality of cuttings is currently being evaluated in young plant...

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Other Projects

Molecular and physiological regulation of adventitious root (AR) formation in Petunia cuttings in response to nitrogen preconditioning and dark exposure

In recent studies of our group it was demonstrated that adventitious root (AR) formation in cuttings of several plant species can be enhanced by high nitroge...

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Molecular physiology of chilling tolerance of Petunia and Euphorbia pulcherrima

Future greenhouse production of ornamental crops in Central and Northern Europe depends on the reduction of energy inputs. Plants with a higher tolerance aga...

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