Soil is host to a myriad of critical coupled hydrobiogeochemical processes, greatly intensified in the vicinity of the root, which provide nutrients, water and life supporting symbiotic associations required for plant growth. It is becoming increasingly clear that plants interact through complex feedback systems with the soil surrounding their roots in a very precise and sometimes deliberate manner, manipulating biogeophysical and biogeochemical conditions which ultimately influence mineral weathering, nutrient and C cycling, water dynamics, and microbial species distribution and abundance. An example of this type of interaction is that of the chemical signaling that occurs in leguminous plants to attract nitrogen fixing microbial symbionts when under nitrogen stress. New work on rhizosphere interactions continues to provide insights into such topics as allelopathy, nutrient acquisition, chemotaxis, and disease resistance, among others. Rhizosphere science is inherently interdisciplinary and covers the interaction of plants, other soil organisms and the physicochemical properties of soils. However, much of the work has remained one-dimensional in that it has been limited to examining one facet of the interaction (e.g. plant physiology of plant-fungal endophyte interactions) while neglecting the tangential effects of these interactions (influence of the plant-fungal interaction on root exudate composition, mineral weathering, soil microbial ecology, C and N dynamics, etc.) on regional or global scales. Furthermore, little is known concerning the genetic controls on below ground processes in plants and how gene expression in plants and in the complex microbial consortium surrounding roots might be interrelated through specific feedback systems. It is clear that progress in unraveling the mysteries surrounding the complex interactions in the rhizosphere and illuminating the controls on coupled hydrobiogeochemical processes influencing nutrient and C cycling and water use efficiency, will require a concerted interdisciplinary effort. The overall objective of the proposed workshop is to bring together researchers from multiple, cross-cutting disciplines to evaluate the current state of rhizosphere science, define the key questions, and map out a transformative research agenda necessary to foster the breakthroughs required to understand rhizosphere processes and their role in ecosystem function, climate change, sustainability, as well as food, energy and water security.
Project Title: Emerging Frontiers in Rhizosphere Science Workshop, Warrenton, VA PI: Paul Bertsch; co-PI Ellen Bergfeld Awardee: Soil Science Society of America Award Number: 1025704 Program Officer Name: Enriqueta Barrera Program Officer Email Address: ebarrera@nsf.gov Report on the Workshop: Emerging Frontiers in Rhizosphere Science Workshop Theme: The Rhizosphere: A Frontier Cross-Cutting Research Area with Implications to Ecosystem Function, Climate Change, Sustainability, and Food, Energy, and Water Security. March 16- 17, 2011 Airlie Center, Warrenton, VA Soil is host to a myriad of critical hydrobiogeochemical processes, greatly intensified in the vicinity of plant roots, which provide nutrients, water, and life supporting symbiotic associations required for plant growth. The rhizosphere is the region within the soil in the vicinity of plant roots where microorganisms, nutrients, and water are relatively abundant and where critical processes that control carbon and nutrient cycles are driven via the complex interactions between plants, microorganisms, and the soil matrix. It is becoming increasingly clear that plants interact through complex feedback systems with the soil surrounding their roots in a very precise and sometimes deliberate manner, manipulating biogeophysical and biogeochemical conditions which ultimately influence mineral weathering, nutrient and C cycling, water dynamics, and microbial species distribution and abundance. Major breakthroughs in our knowledge of rhizosphere processes have been hampered by the complexity of the system as well as the lack of tools available to interrogate these systems. However, the recent advent of robust metagenomic tools, and other "omics" technologies, coupled with advanced analytical techniques and approaches have greatly enhanced our capabilities to investigate these complex systems. Over the past decade, scientists in the EU countries and in Australia have developed organized interdisciplinary research efforts focused on rhizosphere science, while in the U.S. the diverse scientific community working on problems related to rhizosphere science have generally remained fragmented across traditional disciplinary boundaries. Development of an interdisciplinary research strategy in rhizosphere science is essential for developing an understanding of the ecosystem services provided and the coupled hydrobiogeochemical processes fueled by the intricate interactions between plants, soil organisms, and the soil matrix. Such an approach is also required to facilitate the manipulation of interactions in the rhizosphere that will be needed to meet the demands for food, fuel, and fiber by the expanding global population. The objective of this workshop was to bring together scientists from multiple disciplines working on problems related to rhizosphere science in the U.S., to jointly identify frontier research questions that require interdisciplinary approaches, and to develop a strategy for promoting new interdisciplinary activities to address these questions and ultimately push back the frontiers in understanding those coupled hydrobiogeochemical processes and feedbacks in the most dynamic compartment of the critical zone that underpin ecosystem function,. Major Conclusions: Rhizosphere processes involve complex interactions between plants, soil microorganisms and the soil matrix which must be examined as coupled hydrobiogeochemical reactions involving elaborate feedbacks which influence key biophysicochemical reactions in the critical zone that ultimately drive nutrient and carbon cycling and water dynamics, Major advances in understanding coupled hydrobiogeochemical processes and feedbacks within the earth’s critical zone, which are ultimately responsible for ecosystem function, will require integrated interdisciplinary efforts involving biologists, chemists, earth scientists, and computational scientists. Integrating advances in analytical, imaging, spectroscopic, "omic" technologies, as well as the information being generated from their applications to rhizosphere processes across disparate disciplines will be required to unravel the coupled hydrobiogeochemical reactions and mechanisms that underpin critical zone processes and ecosystem function. For the U.S. to become a leader in research and education in rhizosphere science will require the formation of novel inter- and trans-disciplinary approaches and collaboration networks. Major action items: A workshop report was generated by the group and is currently undergoing editing with expected publication early in 2012. The group determined that the U.S. rhizosphere science community should place a bid for the 2015 International Rhizosphere (4) conference, which has been held only in Europe and Australia to date. The bid was submitted on 7/29/2011 and is attached. The group concluded that the importance of developing an organized integrated interdisciplinary research and education effort in rhizosphere science in the U.S. was critical and would pursue the development of a RCN proposal focused on this topic (ongoing).
