DECLARATIONS , OPEN LETTERS AND INFORMATION PAPERS
Argentine-Germany Cooperation: Contemporary Aspects of Plant Sciences
Mariana del Vas
Horacio Esteban Hopp
Marisa Lopez Bilbao
Susana Marcucci Poltri
Alisdair Robert Fernie
Financial Support: The meeting was made possible through the financial support of Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina) and the Max Planck Foundation (MPG, Germany). Financial contribution from the following companies are thanked; Biocientífica, Tecnolab, Argenbio, Monsanto, Dow AgroSciences, CosmoBio, Bioceres, Microlat and INTEA.
Many fundamental reasons motivate collaborative efforts between Argentine and German scientists. First, a long tradition of cooperation ties the relation between Argentina and Germany. Particularly, relations between scientists from the two Nations date back to the friendship of Cesar Milstein with Georges Köhler who shared the 1984 Nobel Prize for Medicine for their breakthrough discovery of the method to accurately produce monoclonal antibodies (Köhler and Milstein, 1975). Nowadays, scientific contributions from joint collaborative efforts between scientists from the two countries can be assessed by simply searching in the web of knowledge portal; about two thousand papers have been published in collaboration in the last five years (ISI; 2002-2007). However, when focusing on the Plant Biology field the number of collaborative contributions is only a couple of hundred papers, representing less than the 10 % of all contributions in the same period, illustrating there is still significant room for improvement.
With this background in mind, plant scientists got together at the main building of the Argentinean National Bank in down town Buenos Aires from December the 3rd to 5th 2007 for a Scientific Workshop of Argentine-Germany Cooperation in Plant Sciences to share and discuss their latest experimental results. The meeting was organized in a frame of a series of scientific events on several topics, so expectations were high. The first Workshop of this series was held in Buenos Aires from 21st to 23rd of November 2005 and ca. 250 participants (scientists, students and technicians) attended the 43 plenary lectures given by Argentine and German scientists. Three main topics were included in the program: Biological Sciences, Nanotechnology and Complex Criminality Research. A year later and focused on Nanotechnologies, a cooperation workshop was organized by the Max Planck Institute for Biophysical Chemistry and the University of Buenos Aires with a similar aim; “to enhance German-Argentine scientific cooperation and to further strengthen research ties between Max Planck Partner Groups and their home Max Planck Institute”. More than 20 scientists from both Institutions gave 26 plenary lectures and discussed common research interests.
In this report we attempt to capture the highlights presented at the Plant Science Meeting and raise the important open questions facing the field. Five related topics representing the corner stones of the plant biology field were selected in an effort to offer a scientific environment to allow initiation and development of strong collaborations that would positively impact on research efforts of the participating groups.
In line with the priorities brought by public scientific institutions in Argentina, we wanted to bring together scientists who are actively researching different problems of the plant biology field as an opportunity to interact and establish new links that may result in new collaborative efforts. And at the same time, different Max Planck Institutes in Germany are continuing exploring the frontiers in the field of Plant Biology and many groups recruit students, postdocs and researchers from Argentina, who in return benefit from the chance to develop their careers in a different research environment, and generally return to Argentina thereafter.
Research on Plant Sciences from both sides of the Atlantic
Plants as sessile organisms need to effectively process and respond to information. They achieve this via complex communication networks throughout the individual plant, thus, assessing signaling functions can be viewed as a start-point to understand their complexity. The Plant Signaling session was opened by Patrick Giavalisco (MPIMP, Germany) with an excellent presentation on a recently developed method for plant metabolome analysis based on Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS). Extremely high resolution and mass accuracy of this technology allow his group to detect ~22,000 peaks and evaluate ~10,000 chemical formulas from crude extracts obtained from Arabidopsis thaliana leaves. By using publicly available DB (ie. PubChem; http://pubchem.ncbi.nlm.nih.gov/) he demonstrated that they are able to predict ~2,600 possible compounds structures. Out of this number, 378 novel metabolites were found in Arabidopsis leaves which have never been described before in this species. This valuable body of information might lead to discover new chemical pathways and moreover, to provide novel insight into metabolic cross-talk and small molecule signaling. In line with this presentation, Ana Laxalt (UNMdP, Argentina) brought about Nitric Oxide (NO) and phospholipid signaling in plants. By using tomato cell suspensions her group proved that NO acts upstream of phosphatidic acids (PA) in the same signaling cascade that leads to the hypersensitive reaction (HR) against pathogens attacks and came out with a xylanase tomato model in which xylanase is perceived by the cell, triggering a rapid NO production that then induces PA formation which subsequently induces ROS production probably via the activation of the NADPH oxidase (Laxalt et al, 2007).
Regulatory signals that determine sexual compatibility in plants is a fascinating subject with obvious implications for crop productivity and plant biotechnology. A key regulatory cascade was summarized by Jorge Muschietti (INGEBI-Conicet, Argentina). After pollen grains germinate on the stigma, pollen tubes pass through the extracellular matrix of the style on their way to the ovules. Searching for pollen-specific kinases encoding genes as potential signal transduction components of pollen–pistil interactions, Muschietti and colleagues characterized two pollen-specific receptor-like kinases, LePRK1 and LePRK2 from tomato (Solanum lycopersicum). Their structure, localization and expression profiles strongly suggest they play key roles in pollen germination and tube growth. While determining the downstream components of LePRK signaling pathway they identified a partner pollen-specific kinase (KPP) that interacts with the cytoplasmic domains of both LePRK1 and LePRK2 in yeast. KPP is a peripheral membrane protein which is phosphorylated in pollen. KPP-like genes are found only in plants and the 14 family members in Arabidopsis thaliana exhibit diverse expression patterns and diverse roles in signaling pathways in other tissues. In parallel, a non-protein small molecular weight compound identified from pistils (named Mr X) specifically de-phosphorylates LePRK2 in vitro (Wengier et al, 2003; Kaothien et al, 2005). Identification of the chemical nature of this compound is likely to represent a key step in the understanding of pollen-pistil interactions.
The regulatory mechanisms of gene expression in plants is an important point of regulation in these signaling cascades and have been rethought in front of recent findings of developmental processes regulated by miRNA-guided degradation of target mRNAs and chromatin/transcription factors interactions. Regarding this point, Franziska Turck (MPPBR, Germany) opened the Plant Transcriptional Control session presenting the development of new tools required to decipher the interconnections of transcriptional networks and chromatin in transcriptional control. Her group is focusing on the study of the effect of surrounding chromatin structure of putative binding site targets of TERMINAL FLOWER 2 (TFL2) transcription factor. Using Chromatin immunoprecipitation (ChIP) applied to DNA tiling microarray that covered the sequence of the Arabidopsis chromosome IV, they mapped binding sites of the chromatin associated protein TFL2 and of several modified forms of Histone 3. With this method they showed that TFL2 and tri-methylatied lysine 27 of Histone 3 (H3K27me3) are co-distributed. In comparison to all Arabidopsis genes, TFL2 target genes are lowly expressed and if expressed at all, their expression is restricted to specific tissues. A high proportion of these target genes are well known for their role in Arabidopsis development. Overall, their data suggest that TFL2 recognizes specifically H3K27me3 in vivo as part of a mechanism that represses the expression of many genes targeted by proteins of the Polycomb repressive complex 2 (PRC2) which is involved in chromatin mark deposition (Turck et al, 2007). In the same session, Javier Palatnik (IBR, Argentina) discussed the regulation of leaf development by miRNA families in Arabidopsis. miRNAs are short non-coding RNAs with variable sequence complementation with target mRNAs that have emerged as key post-transcriptional regulators of gene expression. After a short review on miRNA biogenesis and actions in plants, he described a series of experiments on the related miR159 and mirR319 families leading to the conclusion that miRNAs with similar sequences can have functional specialization through both, sequences difference and expression patterns (Palatnik et al, 2007). The session was closed by Marcelo Yanovsky (IFEVA, Argentina) who talked about the genetic and genomic dissection of the mechanisms mediating light and time perception in plants. First, he introduced the subject by describing how light and circadian clocks interact to measure day length and accordingly adjust developmental responses and the mechanisms underlying light perception and shade avoidance responses. Next, he described the experiments that lead his group to the identification and characterization of an Arabidopsis constitutive shade avoidance mutant (csa1) which shows a shade avoidance phenotype in the absence of shade and an enhanced growth of a bacterial pathogen (Faigón-Soverna et al, 2006) and has a T-DNA insertion in a resistance TIR-NBS-LRR-type gene. Following he addressed the issue of time measurement in plantsand referred to unpublished results on the characterization of a novel mutant (Lic1) that shows a longer circadian period and defects in light inhibition of hypocotyls elongation. Finally Dr. Yanovsky talked about their work on genomic analysis of photoperiodic responses in potato and tobacco. The group established that most of the transcriptional changes take place within the first days of exposure to long days.
The number of data bases (DB) and application tools to perform computational analysis on DNA, RNA and proteins is growing increasingly fast, but the lack of integration between such tools in molecular biology is an important common barrier for extracting new knowledge using these resources. Heiko Schoof (MPPBR, Germany) opened the Plant Computational Biology session presenting the applications of web services and semantic web technologies to integrate data residing at different remote databases. Web services (in this case BioMOBY) are used to analyze and then provide the data in well structured and agreed formated documents available through a central registry. The semantic web provides structure and computer-discernible meaning to the available information. He described the creation of special “aggregators”, which display the data from many remote DB in a single page using the Taverna graphical workflow (http://taverna.sourceforge.net/index.php) for the construction of automatic pipelines. Through the involvement in the annotation pipelines for the Medicago spp and tomato genomes, his group is building a flexible and extensible function prediction system that can utilize heterogeneous data sources beyond sequence similarity or protein domain matches. In the same session Gustavo Parisi (Structural Bioinformatics Group, UNQui, Argentina) presented the Structurally Constrained Protein Evolution model (SCPE) for protein structural alignment and 3-D model quality assessment using evolutionary information. His group has defined site-specific substitution matrices derived from simulation using a structurally constrained model of protein evolution to correlate protein structure and sequence information contained in a set of aligned homologous proteins. Finally, Marcelo Soria (FA-UBA, Argentina) addressed the role of genomics and related disciplines in plant breeding with focus on the Wheat Coordinated Agricultural Project (http://www.plantsciences.ucdavis.edu/MASWheat/index.htm).
Energy production will surely be a bottleneck in the coming years and plants are source of many essential products resulting from energy metabolism in organelles compartments. In the Plant Organelle Biology session Ralph Bock (MPIMP, Germany) started his talk by illustrating about the biotechnological advantages of recombinant protein production using the transplastomic technology. Moreover, he provided interesting experimental data about the attractions of this technology in terms of the high-level accumulation of foreign proteins and the paternal plastid transmission demonstrating the usefulness of plastid transformation as an effective tool to increase the bio-safety of transgenic plants. Finally, he presented very elegant experiments uncovering several principles and mechanisms involved in the functional gene transfer from organellar genomes to the nucleus (Stegemann and Bock, 2006).
Protein complexes constituting the plant mitochondrial respiratory chain have been the focus of many research projects especially in relation of their relevance to power the synthesis of ATP. In the particular case of complex I, Eduardo Zabaleta (UNMdP, Argentina) have shown in his presentation that a group of uncharacterized proteins are attached to the membrane arm of this complex. These proteins are structurally similar to an archaebacterial g-type carbonic anhydrase (gCA) spanning the inner mitochondrial membrane. He has also shown results from experiments with gCA null mutants Arabidopsis plants which suggest these proteins to be essential for assembly of complex I (Perales et al, 2005). When these plants were cultivated in the presence of elevated CO2 concentrations and under different light regimes the results pointed to a role of these proteins in photorespiration suggesting that they could be involved in HCO3 formation to allow efficient recycling of mitochondrial Ci for CO2 fixation in chloroplasts (Zabaleta and Braun, 2007). This session was closed with the presentation of Daniel Gonzalez (UNL, Argentina) who brought about the transcriptional coordination of mitochondrial biogenesis in plants. By starting their work studying the regulatory events of the genes encoding several complexes of the respiratory chain and assuming that mitochondrial biogenesis requires the coordinated expression of genes encoding different mitochondrial components, Gonzalez´s group has concentrated their efforts in a series of dry and wet experiments to search for novel genes putatively involved in mitochondrial biogenesis. As proof of concept they experimentally proved that most of the nuclear genes encoding oxidative phosphorylation components show coordinated expression and at least part of this coordination may operate through a cis-acting regulatory element (site II) in their upstream regions (-50/-300) and factors interacting with them (Gonzalez et al, 2007).
All these contributions might only be extended to the plant kingdom after a broad exploration of the present biodiversity from different perspectives that would allow exploiting it. In the last session, focus was centered on Natural Biodiversity. Iris Peralta (UNCu, Argentina) presented results from a project aiming to recover, evaluate and the social utilization of traditional horticultural landraces in Andean valleys of Argentina; about diversity of vegetable crops in America, and about the needs of genetic diversity in plant breeding programs, through ex situ conservation under the umbrella of the National Genetic Resources System that involves ~90% of the plant germplasm banks in Argentina (INTA, 1988. http://servicios.inta.gov.ar/bancos/). All these objectives were carried out through a thorough exploration and collections made in Cuyo and Northwestern areas of Argentina; by an exhaustive classification using morphological and agronomical traits assisted by molecular markers; and more interestingly through the analysis of the social utilization, mainly food and medicinal traditions, and crop management developed by local rural communities. In the same session Thomas Altmann (MPIMP and Postdam University, Germany) gave an excellent talk about the analysis of natural genetic variation and heterosis in characters associated with growth and leaf metabolism in Arabidopsis thaliana. He presented results from an association mapping study that allowed dissection of genetic factors affecting plant biomass accumulation. By a combination of metabolite profiling and DNA-chip technologies his group focused on the analysis of biomass heterosis (manifested early in Arabidopsis development), and the co-incidence of different QTL affecting the metabolic signature of biomass accumulation (Meyer et al, 2007; Lisec et al, 2008).
The meeting was closed by the presentation of Alisdair Fernie (MPIMP, Germany) who described methodological features of a robust metabolite profile platform based on GC-MS (number and chemical structure of metabolite compounds detected in tomato fruit extracts) (Lisec et al, 2007) and it application to a metabolic QTL study performed on a Solanum pennellii introgression line population (Schauer et al, 2006). Based on different strategies to improve genetic resolution of these QTL (candidate genes approach, recombinant lines and mode-of-inheritance studies) Fernie´s group are narrowing down the genetic mechanism underlying these QTL and in doing so hope to ultimately find additional exotic alleles for use in crop breeding to that of the cell wall invertase described in collaboration with the Zamir group a few years back (Fridman et al, 2004). In formally closing of the meeting Fernie put forward the idea of a return meeting in Germany in two to three years time – an idea that was enthusiastically received.
What do we learn from this meeting? Perspectives
In compiling this short report it became apparent that many of the subjects dealt with could also have been covered in an entirely different biological field. This fact is perhaps testament to the strength of the meeting. Clear collaborative possibilities were also realized and it can be anticipated that these could well serve to boost further German-Argentine collaborations. Given the many possibilities existing for joint funding between our countries everything is in place to take up the challenge of improvement stated in the opening paragraphs of this report.
In an effort to steer the seminal contributions mentioned above, specific actions have been recently taken from both sides; five research groups have been established at Argentine institutions as partners of different Max Planck Institutes focusing their research on different scientific fields such as: Nanotechnologies, Plant Biology and Physics (Max Planck Gesellschaft; Annual Report 2006). More recently, the announcement of a new Max Planck Institute to be located in Buenos Aires was released by an agreement between the National Council of Science and Technology, the Max Planck Society and the Argentine Secretariat of S&T. It was announced that the new institute will start to run by 2010 (Ministerio de Ciencia, Tecnología e Innovación Productiva, 2007: http://www.mincyt.gov.ar/).
The success of this meeting lies not only in its contribution to tie scientific links between Argentina and Germany but also importantly in the possibilities offered to the entire plant research community to directly interacts with experts within specific topics. Ideally such interactions should contribute to the capacity building in this area. This was evidenced here by the fact that in excess of 180 registrations were received and that over 60 attendees were present in each individual session. Considering the size of the regional scientific community in plant research, these numbers say a great deal about the expectancies generated by such events.
This and other successful bi-national workshops and scientific collaborations have convincingly demonstrated that joint basic research between German and Argentine scientists is not only of excellent international level but helps to establish long term relationships among decision making top scientists of the two countries that determine their long term scientific policies. To broaden the economic impact of this interaction it would be of great interest to explore and significantly increase in the future the technology transfer experiences of the Max Planck Society and Argentine scientific institutions. A future workshop could be planned to deal with the issues in the first steps of technology transfer that go from the basic research results to the adoption of knowledge/technology-based companies. Moreover, experience exchanges in designing research projects with high social impact could also be of relevant interest and fruitful for both sides. These could be the first steps toward the establishment of broader collaborative links for example the formation of bi-national companies.
We thank the speakers for allowing us to discuss their presentations and apologize to the speakers whose data could not be highlighted owing to space constraints.
Gonzalez D, Welchen E, Attallah CV, Comelli RN, Mufarrege EF. 2007. Transcriptional coordination of the biogenesis of the oxidative phosphorylation machinery in plants. The Plant Journal 51(1):105-116.
Faigón-Soverna A, Harmon F, Storani L, Karayencov E, Staneloni RJ, Gassmann W, Más P, Casal JJ, Kay SA, Yanovsky MJ. 2006. A constitutive shade-aovidance mutant implicates TIR-NBS-LRR proteins in Arabidopsis photomorphogenic development. The Plant Cell 18: 2919-2928.
Kaothien P, Han Ok S, Shuai B, Wengier D, Cotter R, Kelley D, Kiriakopolos S, Muschietti J, McCormick S (2005) Kinase partner protein interacts with the LePRK1 and LePRK2 receptor kinases and plays a role in polarized pollen tube growth .The Plant Journal 42: 492–503.
Lisec J, Meyer RC, Steinfath M, Redestig H, Becher M, Witucka-Wall H, Fiehn O, Törjék O, Selbig J, Altmann R, Willmitzer L. 2008. Identification of metabolic and biomass QTL in Arabidopsis thaliana in a parallel analysis of RIL and IL populations. The Plant Journal: doi: 10.1111/j.1365-313X.2007.03383.x
Max Planck Gesellschaft, Annual Report 2006. http://www.mpg.de/pdf/jahresbericht2006/jahresbericht2006.pdf
Meyer RC, Steinfath M, Lisec J, Becher M, Witucka-Wall H, Törjék O, Fiehn O, Eckardt A, Willmitzer L, Selbig J, Altmann T. 2007. The metabolic signature related to high plant growth rate in Arabidopsis thaliana. Proceeding of the National Academy of Science USA. 104(11):4759-64.
Perales M, Eubel H, Heinemeyer J, Colaneri A, Zabaleta E, Braun HP. 2005. Disruption of a nuclear gene encoding a mitochondrial gamma carbonic anhydrase reduces complex I and supercomplex I1III2 levels and alters mitochondrial physiology in Arabidopsis. Journal of Molecular Biology 350: 263–277.
Red Nacional de Recursos Genéticos. 1988. INTA: http://servicios.inta.gov.ar/bancos/.
Schauer N, Semel Y, Roessner U, Gur A, Balbo I, Carrari F, Pleban T, Perez-Melis A, Bruedigam C, Kopka J, Willmitzer L, Zamir D, Fernie A. 2006. Comprehensive metabolic profiling and phenotyping of interspecific introgression lines for tomato improvement. Nature Biotechnology 24: 447-454.
Turck F, Roudier F, Farrona1 S, Martin-Magniette ML, Guillaume E, Buisine N, Gagnot S, Martienssen RA, Coupland G, Colot V. 2007. Arabidopsis TFL2/LHP1 Specifically Associates with Genes Marked by Trimethylation of Histone H3 Lysine 27. PLoS Genetics 3 (6) e86.
Wengier D, Valsecchi I, Cabanas ML, Tang W-H, McCormick S, Muschietti J (2003) The receptor kinases LePRK1 and LePRK2 associate in pollen and when expressed in yeast, but dissociate in the presence of style extract. Proceeding of the National Academy of Science U S A 100(11): 6860–6865.