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This 'Sonderforschungsbereich 607' (SFB 607) is funded through the 'Deutsche Forschungsgemeinschaft' (DFG) and represents an interdisciplinary research program that integrates 20 projects of 18 working groups located in the area of Munich, Germany
'Growth' and 'Parasite Defense' - these are the keywords of this interdisciplinary research initiative ('Sonderforschungsbereich 607', SFB 607) currently being conducted in the Munich area/Germany, as they reflect one central challenge in plant metabolism of coping with two basic demands in resource allocation. Which are the mechanisms that partition energy, carbon, water and nutrients between these two physiological demands and that control the competition for these resources within individual plants and between plants in stands? Which factors do determine this regulation, and by what means do induced signals become translated into effective plant responses? And overall, which are the 'cost/benefit' relationships in the control of resource allocation? These questions characterize an internal conflict of plants: necessity for growth as a pre-requisite for being competitive, and necessity for defense against biotic stress imposed by parasites (pathogens, herbivory; HERMS & MATTSON 1992; ZANGERL & BAZZAZ 1992). As these two aspects define the capacities of resource sequestration and retention, they reflect the core of individual plant fitness (BAZZAZ 1997) and are assumed to be controlled through common mechanisms in resource allocation between the primary and secondary metabolism (FRITZ & SIMMS 1992; KOCH 1996; BATZ et al. 1998).
The conception has gained in importance during the past decade that the development and existence of plants and stands, in particular their integral (or system) properties, can be understood only in terms of their allocation patterns. The control of allocation, as driven through mechanisms that link internal resource partitioning to external availability, is much less understood, however, than the broad diversity of discrete physiological processes. These alone, without being conceived as parts of mechanistic scaling schemes across plant and stand properties, cannot comply with the request for understanding functional integration. With respect to this request, research demand is rather similar irrespective of the kind of plant under consideration: wild forms or economic plants - or, herbaceous or woody species. SFB 607 is directing its research interest to economic plants like potato, barley, grasses and legumes, apple, beech and spruce. This research demand is accounted for by a number of conceptual review books, e.g. by MOONEY et al. (1991) 'Plant Response to Multiple Stress', SCHULZE (1994) 'Flux Control in Biological Systems' or BAZZAZ & GRACE (1997) 'Plant Resource Allocation'. It was this latter volume that was published in parallel to the beginning of the research of SFB 607 and broadly complies with its aims (see BAZZAZ 1997):
- How rapid and sensitive is allocation response to resource withdrawal by phytophages or pathogens, and how do shoot and root interact when re-adjusting resource flux?
- In what ways do structural interactions between neighboring plants result in modifications in allocation and allometric relationships as the basic mechanisms in plant competition?
- Do 'strategies' in allocation (e.g. retranslocation, reduction or stimulation of organ formation and performance) differ between plant life forms and environmental conditions?
- What kinds of signals are required during flux control, and how is the molecular level ('genetic switches') linked to the resource flux at the organ and whole-plant level?
- By what means is fine-root turnover controlled? Does resource allocation to root symbionts compete with that to parasite defense? What about the 'opportunity costs', if resources are invested alternately between the needs for staying competitive (in terms of maintaining or increasing resource sequestration), meeting the resource demands by root symbionts, and ensuring the defense against parasites?
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In particular, the latter question reflects the transitions in the control of resource allocation between the demands of individual plant fitness: sequestration and retention of resources. The aspect of parasitic and mutualistic interactions in allocation between plants and micro-organisms has been highlighted recently by a special issue of 'Physiological and Molecular Plant Pathology' (HEATH 2000), and mechanisms in signal transduction continue to be a focus in host/parasite research (GRANT et al. 1996; PONCHET et al. 1999). The research questions raised above are mirrored in the project structure of SFB 607: The clarification of 'plant-plant' interactions (intra and inter-specific competition), 'plant-mycorrhizosphere' relationships (potentially conducive to competitiveness) and 'plant-parasite' interactions (adverse to competitiveness) is being based on the analysis of the common, underlying mechanisms of allocation at the biochemical and molecular level (including the 'genetic switches', Fig. 1). In this way, research issues of high priority, given the current state of knowledge, are being covered: control of resource allocation, competitiveness and stress sensitivity at the individual-plant and stand level (BAZZAZ 1997; MATYSSEK & INNES 1999; CEULEMANS et al. 1999; NORBY et al. 1999), effects of parasitic and mutualistic interactions on assimilate flux (HALL & WILLIAMS 2000; HEATH 2000), mechanisms of signal transduction in plants (GRANT & LOAKE 2000), genetical basis of plant defense against parasites (OBERHAGEMANN et al. 1999), control of differential gene expression (YANG et al. 1999). Consequently, the rationale of SFB 607 provides the postulated link in basic research across molecular biology and ecophysiology (ZANGERL & BAZZAZ 1992).
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