I am proud to have been chosen as scientific advisor for the RECBREED project. I have been part of the framework 5 and 6 projects which preceded the presently running one. With many scientists in this network I had previous collaborations; I deeply admire the scientific competence, enthusiasm and successful strategies of the 7 closely interacting partners.

The world-wide basis for food and feed is represented by plants. The world is changing, due to population increase, erosion of important land resources and climatic disturbances. To be able to cope with increased demand for food and feed crops we will have to be more productive and better adapted to change. Classical breeding efforts, for at least the last 10 millennia, provided the basis for settled life, civilization and art. However, classical breeding is too slow for our fast-developing world. It will continue to be important, but will have to be assisted by molecular breeding. This procedure allows development and use of tools to enhance the speed and/or precision of exchange of genetic material. This exchange of genetic material, called homologous recombination, is a process at the basis of evolution, including man-made evolution (i.e. breeding). To study and use recombination is exactly the goal of RECBREED, the synonym being a chimera of recombination and breeding.

The strategies generally used and adopted by the network partners are, at one hand, to enhance the chance of transgenes to integrate at specifically chosen loci in plant genomes (called gene targeting, GT). This strategy allows faithful expression of desired transgenes, often in place of endogeneous genes. On the other hand the goal is to influence the efficiency of sexual reproduction and with it meiotic recombination. This procedure will permit faster breeding cycles in introducing gene-pools from wild plant relatives into well established cultivars. In some combinations of breeding partners genetic recombination is low due to reduced homology in DNA sequence. With the introduction into plants of genes coding for special enzymes allowing sequence divergence to be accepted the rate of meiotic recombination is expected to increase. All these goals are integrated in the RECBREED network in a way that all 7 partners, 5 of them at academic positions and two of them being in industry, interconnect.

The 7 partners, all of them originally plant molecular biologists with a keen interest in molecular breeding, arranged their workload, called workpackages (WPs) around the 3 steps known to be critically important in the process of homologous recombination:

WP1 concentrates on the initial double-stranded incision on DNA, brought about in somatic tissue by environmental influences (such as UV-radiation) as well as by internal factors including replication errors. The WP uses modern sophisticated methods to accomplish site-specific breaks. In meiosis these breaks are initiated by meiosis-specific enzymes; heir function is also being redirected in efficiency and specificity in this network.

 WP2 is involved in studying the invasion of the two interacting DNA partners into each other. Specific proteins have been shown, particularly by the network-partners, to strongly influence the choices in strand invasion and heterduplex formation. It is indeed difficult to imagine, on a 3-dimensional scale, how two different DNA molecules interact in a sequence-specific manner, intermingle with each other and finally allow resolution to single chimeric molecules.

WP3 work concentrates on the analysis of stabilization and resolution of intermediates in recombination. Dedicated proteins have been shown by the network partners and others to stabilize recombination intermediates and to allow them to interact with proteins that permit their resolution to recombinant DNA structures.

WP4 will combine results from all academia partners in search for a synergistic effect of multiple genes on recombination. This package will start at a later stage of the project and will therefore focus on the Arabidopsis model system.

There is a strong overlap of different groups and different workpackages, i.e. some groups work on several WPs, thus ensuring optimal scientific interplay and exchange of material (see Figure). These interconnections are fortified by frequent scientific meetings, inside and outside of the network. Also visits of members of the network to other network-locations are and will be an important, if not necessary part of exchange of scientific knowledge.

 

 

 

 

The basic scientific work on somatic and meiotic homologous recombination has been accomplished in the model plant Arabidopsis thaliana.This is due to the fact that this species is most easily tractable for genetic, molecular biological, genomic and biochemical studies. It is one of the many advantages of the RECBREED consortium that a wealth of information has been gathered by the network partners on the mechanism of homologous recombination, already prior to the present collaborative effort. However, for applied purposes the knowledge gained in Arabidopsis thaliana have to be transported to agriculturally important species. Well incorporated into the network are industrial partners who apply knowledge on different aspects of homologous recombination, especially gene targeting, to crop plants such as tomato and maize. Encouraging results, especially for gene targeting, have been obtained by these partners. It is most pleasing to see that the flow of information from laboratories in academic institutions to those in industry is reliable, as is the flow in the other direction – for mutual benefit.

Our continued occupation of this planet depends on sustainable resources such as food, the basic part being plants. Research on plants therefore is essential. It is gratifying to see that the scientific community of the EU has acknowledged this fact and has provided the basis for research in plant breeding, including molecular approaches to it. Thus we hope for continued support of this FW7 network and its potential follow-up projects, both with regard to work on model-plants as well as on important crops.

 

Barbara Hohn, FMI.
Scientific advisor,
RECBREED