As soon as candidate growth and development-related genes will have been identified, sense and antisense constructs will be introduced into Malus, Prunus and Vitis plants, using transformation procedures already in use in participating laboratories. After initial characterization of transgene copy number and expression features, transgenic woody plants showing increased or decreased expression of the genes of interest will be selected and micropropagated. Using the same tissue culture conditions that will have been used to select development-related genes, these transgenic plants will be scored for morphological modifications. After transfer to greenhouse conditions, these plants will also be screened for growth and development alterations in vivo.
Many of the regulatory circuits underlying plant growth and development processes still remain to be discovered and understood. However, it has become increasingly clear that basic signal perception and transduction mechanisms (involving cytoplasmic calcium ions) and their associated biochemical cascades play a key role in these phenomena, like in many others. From this point of view, the regulation of tree growth and shape constitutes one of the most challenging issue, not only because of its apparent complexity, but also because of its major impact on many agricultural or forestry problems.
The development of plant molecular biology techniques has allowed to isolate tools that can now be used to understand, at the molecular level, some of these processes. Apple tree DNA probes, corresponding to genes whose products are likely to be involved in plant growth and development regulation, will be used to dissect molecular events related to the perception and transduction of developmental or morphogenetic signals. This will be achieved by taking advantage of in vitro tissue culture models that are available for Malus and Prunus species. At the same time, RNA fingerprinting methods will be used to extend the list of available probes. The transgenic aequorin system will also be used, in order to collect data concerning cytoplasmic Ca2+ level variations in response to specific signals in these woody plants. This will help to question the relationship between observed variations in specific gene expression levels and signalling pathways.
Funding SchemeCSC - Cost-sharing contracts