Over the past eight years since the German re-unification in 1990 a number of new university departments and research groups studying aspects of plant-microbe interactions using molecular genetic tools have been established in the "Neue Laender." These groups are financially supported (renovated or new labs, new equipment, etc.) by the Federal as well as the local ("Land") governments. As there is a strong focus on molecular plant genetics and plant microbes at the University of Halle where I am located, as well as the independent research institutes nearby, I will begin my report with these institutions before discussing those in Dresden and Jena.

Several departments are devoted to plant-microbe interactions: Research in the Department of Phytopathology and Plant Protection (head: Holger Deising, http://www.landw.uni-halle. de/lfak/inst/pzps/pbppp.htm; e-mail: deising@landw.uni-halle.de) is focused on molecular fungal-plant interactions. Fungal cell wall biogenesis and modification of cell wall polymers is studied in Colletotrichum graminicola. The role of several chitin synthase genes in infection structure differentiation and chitin deacetylation during the process of fungal penetration of and establishment in the plant cell are main projects. In addition, mechanisms of salycilate-induced resistance in broad bean against fungal pathogens are being investigated. One focus is the cloning and study of the regulation of salicylate-responsive genes.

Plant pathogenic bacteria and their interactions with plants are studied at the molecular and genetic level (in both the bacterium and the plant) in the Department of Plant Genetics at the Institute of Genetics (head: Ulla Bonas, http://www.biologie.uni-halle.de/Genetics/index.html; e-mail: bonas@genetik.uni-halle.de). The interaction between Xanthomonas campestris pv. vesicatoria and its host plants (pepper and tomato) is used as a model system. Current research projects are focused on the analysis of the bacterial Hrp type III protein secretion system and the avirulence gene avrBs3, and on plant resistance genes. The AvrBs3 protein is probably injected into the plant cell where it acts as a trigger of the specific cell death reaction in the corresponding resistant pepper line. To unravel the initial signaling events, the Department is currently isolating plant proteins interacting with AvrBs3 in the yeast-two hybrid system. In addition, the Department has initiated a map-based cloning approach to isolate resistance genes from pepper and tomato genetically interacting with avrBs3 and the homolog avrBs3-2.

Studies on plant-microbe interactions are also among the central research topics at the Leibniz Institute of Plant Biochemistry (IPB, home page: http://www.ipb.uni-halle.de) in Halle. The IPB is a non-university research institute with basic funding from the Federal and Land governments. In the IPB Department of Stress and Developmental Biology (head: Dierk Scheel, dscheel@ipb.uni-halle.de) non-host resistance of plants against fungal and bacterial pathogens is investigated using several experimental systems. Plant plasma membrane receptors apparently recognize typical microbial or plant cell wall constituents released during early stages of pathogen attack. Upon binding of these elicitors to their receptors, signal transduction processes are initiated that activate a multicomponent defense response. The molecular mechanisms of pathogen recognition and local as well as systemic signaling events are analyzed in Arabidopsis, tobacco, potato and parsley using different Phytophthora and plant-pathogenic Pseudomonas species. The IPB Department of Secondary Metabolism (Head: Dieter Strack) studies the symbioses between obligatory biotrophic fungi (e.g. Glomus intraradices) and the roots of terrestrial plants (e.g. barley, wheat, maize, tobacco, tomato). The arbuscular mycorrhizal fungi promote growth of the host plant, which in turn supplies carbohydrates to the fungus. Current research in the Department focuses on fungus-induced expression of the non-mevalonate plastidic methyl-erythritol-phosphate (MEP) pathway of carotenoid biosynthesis and the accumulation of apocarotenoids (C14-acyclic polyene esters and C13-cyclohexenone derivatives) in mycorrhizal roots. Fungal induction of carotenoid metabolism is accompanied by transient accumulation of phenolics (hydroxycinnamic acid amides) and jasmonic acid. One of the major goals is to understand the role of jasmonic acid and the involvement of phenolics and carotenoid metabolites in the developmental program of the fungus and functional maintenance of the symbiotic plant-fungus relationship.

Another Leibniz-Institute is located approximately 60 miles from Halle, in Gatersleben: the Institute of Plant Genetics and Crop Plant Research (IPK, http://www.ipk-gatersleben.de/englisch/home-uk.htm). The IPK, formerly Zentral-Institut für Genetik und Kulturp-flanzenforschung of the GDR, was founded in 1992. The Institute's objective is to carry out basic and applied research in the field of crop plant genetics as well as the conservation and evaluation of the genetic variation of crop plants, their progenitors and relatives. Among the interdisciplinary approaches, the following are relevant for plant-microbe interactions: the IPK harbors a well-known gene bank (contact: A. Boerner, e-mail: boerner@ipk-gatersleben.de), with a collection of approximately 100,000 accessions of many different plant species, a number of which have been tested for the presence of disease resistance genes. Two research groups are involved in map-based isolation of disease resistance genes. The Molecular Genetics of Cereals group (head: Andreas Graner, e-mail: a_graner@IPK-Gatersleben.de) is focused on molecular mapping of genes in barley conferring resistance to various fungal and viral pathogens and on the development of corresponding, selectable markers to be assayed by PCR-techniques. In addition, a comparative map of rice chromosome 1 and barley chromosome 3 was constructed to possibly exploit synteny for gene isolation. The main goal of the Gene and Genome Mapping research group (head: Martin Ganal, e-mail: ganal@IPK-Gatersleben.de) is the genetic mapping and molecular isolation of agronomically important traits in tomato, barley and wheat. One of the tomato projects deals with mapping and isolation of disease resistance genes, e. g., the gene Hero, conferring broad spectrum resistance against Globodera rostochiensis. The work on cereals is focused on the two most important crop plants in Germany, wheat and barley. For barley, techniques are being developed for the map-based cloning of resistance gene Rh2 against scald (Rhynchosporium secalis).

There are a number of interactions and cooperations between the research groups in Halle (university and IPB) and the IPK Gatersleben. One example is a research network (Sonderforschungsbereich;SFB 363) funded by a grant by the Deutsche Forschungsgemeinschaft. The overall theme of the SFB 363 (http://www.sfb363.uni-halle.de/) is Plant Cell Biology (head: Ulla Bonas). Funding is for 3-year periods (up to a total of 12 years if evaluations are positive) and is granted to basic research projects on the basis of novelty and cooperation. The SFB 363 was founded 7 years ago and currently consists of 17 research groups.

In the new Faculty of Biology, the Department of Molecular Genetics (Head: Michael Göttfert, e-mail: mgoettfe@rcs.urz.tu-dresden.de; http://www.phy.tu-dresden.de/bio/genetik/gen-home.html) studies the genetic basis of the interaction between Bradyrhizobium japonicum and legumes with a focus on transcriptional regulation of the bacterial genes involved. In addition, a physical map of the B. japonicum chromosome has been established, and part of the genome has been sequenced.

The Institute of Microbiology in Jena houses a fungal collection of roughly 8,000 isolates, mainly zygomycete and ascomycete plant pathogens. This Fungal Reference Centre (head: Kerstin Voigt, e-mail: b5kevo@rz.uni-jena.de) together with the General Microbiology and Microbial Genetics group is involved in research programs on molecular phylogeny of fungi based on protein-coding genes and on development of molecular probes for a variety of plant pathogens.

There are three departments working on various aspects of prokaryotic and eukaryotic microbes. The Department of Applied and Environmental Microbiology (head: Gabriele Diekert, e-mail: b8diga@uni-jena.de; http://www.uni-jena.de/biologie/tech_mikrobio/) concentrates on biochemistry and physiology of degradative capacities of anaerobic prokaryotes (methyltransferases, dehalorepiration). The Department of Microbial Phytopathology (head: Erika Kothe, e-mail: ekothe@pmail.hki-jena.de) studies ectomycorrhizal relationships between Tricholoma species and their host plants pine and spruce, as well as on mating type differentiation and the characterization of MAT loci in the basidiomycete Schizophyllum commune. The Department of General Microbiology and Microbial Genetics (head: Johannes Wöstemeyer, e-mail: b5wojo@rz.uni-jena.de; http://www.uni-jena.de/biologie/mikrobio/) also, besides other projects, works on mycorrhizal interactions. The experimental system is an arbuscular mycorrhizal fungus, Glomus intraradices and its host plant clover. The aim is to perform expression studies on key genes that control the cell cycle in the fungus and the host. The group is also involved in analyzing at the molecular level the host relationships between the mucoralean fungus Parasitella parasitica and its numerous fungal hosts. The parasite is a fusion biotroph. Infection is accompanied by the formation of a limited cytoplasmic continuum between the partners. During this process genes are stably transferred from the parasite to the hosts.

The Institute of Phytomedicine (head: Andreas von Tiedemann, e-mail: avt@agrarfak.uni-rostock.de; http://www.agr.uni-rostock.de/phyto/version_gb/research.htm) works on a number of different plant pathogens and their control. The group is developing and testing biological plant protection systems for control of fungal pathogens, and biological control of root knot nematodes. Another focus is on oxidative stress by pathogens and environmental influence and the impact of atmospheric trace gases on fungal plant diseases. Some of the current projects focus on the role of active oxygen radicals in pathogenicity of Botrytis cinerea, genetic characterisation of Verticillium dahliae populations, and the use of Coniothyrium minitans for control of Sclerotinia sclerotiorum in infested agricultural soils.

As you can see, there is a lot happening and I must say that for me personally these are exciting and challenging times. I apologize for being incomplete and would like to thank my colleagues in Halle and Jena for their help.

I would first like to thank Pierre de Wit and all his helpful colleagues for the excellent MPMI Congress Meeting in Amsterdam in July this year. Not only was it an exciting science meeting but a very memorable one as well. The momentum in the various sections of the field has not been lost during our three year break from the 1996 get together. This is one of the most pleasing aspects to all involved in the organization of the IS-MPMI.

I would like to wish Jan Leach the very best as the incoming President and to thank the various members of the Board and the folks, Kayleen and Steve at headquarters for their help over the years.

We have, however, another challenge that is now starting to gather momentum - the increased anxiety of the general public to the sale and use of genetically modified plant products. At the end of June the environment ministers of the European Union met in Luxembourg with the aim of examining the rules for approving new Genetically Modified Organisms (GMOs). This was largely in response to the growing public concern about the safety of gene technology especially as applied to food.

The EU's Commission has proposed changes to the process by which new GMOs will be authorized in the future. All ongoing applications are currently blocked until a new approval process is in place which might take up to 18 months. France and Greece, supported by Italy, Denmark and Luxembourg, have led calls for a moratorium on their use. The environmental pressure group, Greenpeace, welcomed the moratorium stating "GMOs are an environmental threat and an unjustified experiment with food" and it hoped that a temporary halt to approvals might lead to a future complete ban.

In July, Greenpeace became more militant in UK by sending its "eco-warriors" in on dawn raids to trash GMO field crop trials. The press and the TV reporting, generally in Britain, during this period was very negative to the use of GMOs. In early August, the pharmaceutical company AstraZeneca, which has a very substantial commitment to GM food, was "reconsidering" its "options" in this area of agribusiness. The "feed-back signal" from Europe to the USA has now been successful in that the Department of Agriculture and various farmers are reconsidering their commitment to GMOs in the future.

What has this got to do with our IS-MPMI? Well, I suspect that a substantial amount of recent molecular genetic research in areas of Plant-Microbe Interactions has been based on the notion that one day GMO plants, containing spin-offs from this research, would be used in 21st century agriculture. So what has happened? There has been a growth of an anti-science movement, fear of multi-national corporate control of food production, arrogance by the multi-nationals in their public relations, and a miscalculation by the corporations and the science community of the public response to GMO technologies when applied to food products as opposed to healthcare and medicine for which there has been greater public support to date. There are a whole series of overlapping issues and various political agendas running in parallel here and the public responses often do not discriminate between them but just react with a blanket condemnation. The two opposite views have been summarized well in the recent New Scientist, 14th August, pages 46-47.

If we do not listen perceptively and carefully to the public demands and become an active and informed part of the debate, we in the PMI fields of research might be looking at 5-10 years or more inhibition of GMO development. Therefore, I ask all participating scientists in PMI research to take every opportunity to explain to the general public why they are doing their research, evaluating the positives and the negatives, and to seek to have support for well thought-out risk assessment experiments. Remember the question that Professor John Beringer poses to the reader (New Scientist, 14th August, page 47): "Why did they burn witches in the Middle Ages? Easy. It was easier to kill them than to find out if they really caused harm!"

Barry Rolfe

Introduction

The study of nodulation and nitrogen fixation provides insight into plant developmental processes as well as mechanisms of plant-microbe interactions. Fueled by the success of Arabidopsis, model legumes have facilitated a concentrated and cooperative research approach into this exciting area of plant science. While model legumes are not suited for all types of investigation, they excel in the analysis of nodulation biology and mycorrhizal associations, both processes being absent in Arabidopsis (Kolchinsky et al., 1996).

Functional genomics combines structural analyses of the genome with expression studies. Indeed, classical structure: function paradigms are being addressed. Because of bioinformatics and new multiplexing technologies such as high throughput sequencing, microarrays, virtual mapping, and multi-locus DNA profiling, multiple genes can be analyzed concurrently, permitting investigation of gene systems, rather than single genes.

For legumes, two species, namely Lotus japonicus and Medicago truncatula, have developed as tools of genomics. Although some duplication of effort, division of already limited funding sources, and friendly competition are expected, one sees advantages: the possibility to compare legume genome structure and function to develop paradigms and data sets useful for other legumes such as soybean, chickpea, bean, and pea, which are plagued by either larger genomes, low transformation frequencies, or both. Additionally, commonalties and differences produced by the different nodulation patterns (determinate vs. indeterminate nodule type) can be addressed.

These features have been extensively reviewed (Handberg and Stougaard, 1992; Jiang and Gresshoff, 1997). The plant is the diploid (n=6) relative of L. corniculatus (birdsfoot trefoil), a forage legume. Chromosomes are heteromorphic. The genome size is given as "two and a half times" that of Arabidopsis. Since this value has changed over the last decade, but with its sequencing being nearly completed (J. Byrum, World Soybean Research Conference, Chicago, Aug. 1999), one should assume a L. japonicus genome size of about 300-350 Mb. Genotype Gifu was arbitrarily chosen as the reference genotype.

Mesorhizobium loti strain NZP2235 nodulates L. japonicus efficiently, but has a limited genetic database. It is of additional value to Lotus research that the broad host range bacterium, NGR234, also nodulates and fixes nitrogen with L. japonicus (Hussain et al., 1999) and provides information, including bacterial mutants, a completely sequenced and transcriptionally mapped 534 kb symbiotic plasmid and structural knowledge of lipo-oligosaccharide nodulation factors and surface molecules involved in plant-microbe interactions.

To facilitate mapping of genes, several useful populations were produced. The Aarhus lab created an interspecific cross between L. japonicus cv. Gifu and L. falciflora. Molecular polymorphisms based mainly on AFLPs and EST were mapped. Our group made a F2 population from a cross between L. japonicus ecotypes Gifu and Funakura (Q. Jiang, pers. comm.). Molecular markers were mainly based on DAF markers and supplemented with morphological markers. The F2 population was advanced to an F6 of recombinant inbred lines (RILs) to facilitate fixation of markers as homozygotes. An additional F2 population of a cross between Funakura and Gifu carrying the har-1 (hypernodulation and altered root phenotype) mutation is available.

The F2 map at present contains about 60 markers, and spans 500 cM in 11 linkage groups. Linkage groups are defined by dominant DAF markers from either parent as well as some co-dominant markers obtained by using soybean SSR primers. Group joining using codominant markers is urgently required. EST polymorphisms were detected in the Funakura/Gifu cross and are being mapped on the RIL map. RILs are available for international sharing (see Limani et al., 1999). The har1 gene was mapped between two DAF markers, but at distances of about 5-7 cM, not close enough for positional cloning. An allelic mutation, sym16, was also mapped closer to two AFLP markers on the interspecific map (J. Stougaard, pers. comm.). Map-based cloning of the har1 (sym16) locus is in progress.

Pillai et al. (1996) described the first isolation of BACs and YACs of L. japonicus. Clones were small on average and their number was limited. A library of Gifu was constructed in vector V41, which is transformable into Lotus (A. Men, unpublished data). The average insert size is about 95 kb. With 25,000 clones being arrayed in 384 well format as well as on Nylon membranes, this represents a 6-7 fold genome coverage. Pools and filters are available upon request and for a small handling charge. The V41 library was derived from nuclei of dark treated plants and has low organelle DNA content. Clones homologous for Lotus ESTs were isolated. A second library was constructed by Skot et al. (pers. comm.) with Gifu but using vector pBACBelo11 (F factor-based). Insert size is about 75 kb, with about 30,000 clones available. Having multiple libraries increases the chance for successful gene detection.

Considerable effort was placed into this aspect of functional genomics. Szczyglowski et al. (1998) described the isolation of about 100 nodule-related ESTs. Further characterization of some of these was published. Major efforts exist in Japan (Dr. Tabata at the Kisawa Institute, Chiba) and Germany (M. Udvardi, MPI Golm, pers. comm.) to isolate and sequence ESTs from L. japonicus. For example, the Golm group has isolated 1000 Lotus nodule ESTs, sequenced them, and deposited the information in a public database. Funds for sequencing another 10,000 ESTs are available from the German group. The Aarhus group has sequenced 640 ESTs and will deposit these. The Japanese group aims to release all 40,000 ESTs, although it is unclear at this moment, how far the program has progressed. cDNA libraries for nodules, symbiosome membrane proteins, roots and shoots are available.

To couple structure with function, genetic analysis of mutants is essential. A large number of symbiotic mutants affecting mycorrhizal as well as Rhizobium associations exist in L. japonicus (Szczyglowski et al., 1997; Schauser et al., 1998; Wegel et al., 1998). Mutagenesis was carried out by EMS, fast neutrons, T-DNA as well as Ac/Ds insertions. Fast neutron-induced mutants isolated in our laboratory include non-nodulators as well as non-fixers (A. Hussain, pers. comm.). Such mutants provide the advantage that if large regions of the genome are deleted, gene addition of recessive alleles will lead to gene expression. Molecular comparison of deletion mutant vs. wild type can reveal quickly linked molecular markers. Mutant and parent can be used as near-isogenic material differing only in the deleted region containing the gene of interest. For example, in Glycine soja our group used fast neutrons (provided by Dr. Helmut Brunner, IAEA, Vienna) to make a supernodulation mutant (fn37), that lacks about 100 kb of DNA covered by a BAC contig. Clearly the supernodulation gene is located on that region as defined by the physical loss of endclone markers, ESTs, and RFLPs (A. Men and A. Hussain, pers. comm.; Gresshoff et al., 2000).

The most exciting advance in L. japonicus is the recent application of insertional mutagenesis and subsequent gene isolation (Schauser et al., 1999). T-DNA insertion allowed the isolation of a non-nodulation mutant (nin1). Characterization of the flanking DNA revealed a transcriptional factor gene, which shares homology to a gene involved in gametogenesis in the green alga Chlamydomonas reinhardtii. Interestingly, but perhaps insignificantly, both nodulation and gametogenesis are regulated by external nitrogen supply. This is the first time that the gene causative for a symbiotic phenotype has been isolated. Up to now we were restricted to a collection of symbiotic mutants for which the causative gene was unknown, or a collection of well-characterized nodulin clones, for which a phenotype, and thus causal involvement, was not demonstrated.

Mutants altered in both nodulation and mycorrhizal association were isolated and characterized (Wegel et al., 1998). This interaction between symbiotic processes on a genetic level supports agronomic and biological studies suggesting the same.

Lotus japonicus is efficiently transformed by Agrobacterium tumefaciens as well as A. rhizogenes (Handberg and Stougaard, 1992; Stiller et al., 1997; Oger et al., 1996; Limani et al., 1999). Transgenic plants are fertile and nodulate. This ability has been used to study promoter activities of symbiotic genes [e.g., enod40 (an early nodulin gene of unknown function), nod26 (a symbiosome membrane protein gene (M. Udvardi, pers. comm.) or lbc3 (leghemoglobin)] fused to the beta-glucuronidase (gus) gene]. Over-expression and anti-sense studies with genes of symbiotic interest such as the root-specific glutamine synthetase (Limani et al., 1999), uricase, auxin-response elements, the putative lectin-like, the dominant ethylene insensitivity receptor ETR-1 (D. Lohar, pers. comm.), and PEP-carboxylase (D. Lohar with K. Schuller, Adelaide) are being conducted.

One of the unique applications of high transformation frequency of L. japonicus comes through promoter-trapping as well as activation tagging (J. Webb, pers. comm.; M. Chirazzu, pers. comm., H. Schlaman, pers. comm.1999). The former approach uses a promoter-less reporter gene such as gus, delivered through an insertional vector such as T-DNA. The second approach uses a strong promoter cassette to activate genes. One dreams of a spontaneously nodulating plant, defining new genes in the receptor or the connected signal transduction pathway.

The promoter trapping technique allows: (i) evaluation of the expression pattern of a gene combining biology with genetics; (ii) detection of a gene that is expressed in multiple organs such as roots and nodules, which would otherwise not be difficult to access by molecular tests such as subtractive hybridization or differential display (Appel et al., 1999); (iii) isolation of flanking DNA assuming that a single insertion line was isolated or segregated; and (iv) isolation of a mutant phenotype in a homozygous segregant assuming that the trapped gene is not redundant on either genetic (i.e., duplication), biochemical (i.e., alternative pathways), or physiological (i.e., the activity is a response) levels. Promoter trapping has been successful (Martirani et al., 1999). About 2.2% of A. tumefaciens transformed lines (using strain LBA4404 carrying a pDBIN19GUS) showed expression in either early root or nodule development (D. Lohar and J. Stiller, pers. comm.). Trapping frequencies were 5-fold higher using A. rhizogenes transformation of roots (Martirani et al., 1999). However, the significance of this difference requires further investigation. It may reflect preferential insertion into tissue-active genes, or an artifact of the selection system. For example, we discovered that Agrobacterium strains carrying the promoter-less gus construct were able to express glucuronidase activity, presumably from promoter read-through. Insertion of the gus-intron gene prevented this residual, but problematic activity. Great care needs to be taken before interpreting blue tissue and positive PCR bands as evidence for transformation!

Schlaman et al. (1999) constructed a new trapping vector in which the gus gene is interrupted with a plant intron, the gfp gene is fused to the gus gene, and several termination, and intron splice sites have been introduced in the upstream region. Using this vector they detect about 10% nodule related trapping.

We have isolated and propagated a high number of tagged lines with varying expression patterns. Different parts of the root, or nodule are concomitantly expressing the reporter gene, showing that common genes are used in "developmental symphonies." To illustrate, a few lines will be described.

Line FATA MORGANA expresses gus in the nodule interior, even at an early stage before emergence from the cortex. Mature nodule are intensively blue suggesting a strong promoter. Some activity, seen as a faint "mirage" in the uninoculated plant roots exists in the pericycle. Flanking DNA suggests that the FATA MORGANA gene is similar to the leghemoglobin multigene family of legumes. While it is rewarding to prove that a known nodule gene can be trapped, it is even more significant that the gene has residual expression in the pericycle, and that this expression is not affected by inoculation. The phylogenetic and ontogenetic significance of such expression pattern is immense as it may provide a clue of where symbiosis genes originated.

Line TIMPA is similar but expresses only in the nodule. Expression is intense even 4 days after inoculation. The primary transgenic of TIMPA, as well as FATA MORGANA, has three gus inserts of which only one is active as judged by segregation analysis. A general conclusion in this area is that insertions are independent and tend to segregate from each other.

Line CHEETAH is again similar to the previous two as it expresses in nodule primordia and nodules. However, expression in the nodule subsides 11 days after inoculation with Rhizobium, first being restricted to the nodule vascular trace, then the nodule base, then disappearing totally by 14 days after inoculation. CHEETAH expression in nodule primordia can be detected 24 hours after inoculation. In parallel CHEETAH also expresses in root meristems (both apical and lateral), where expression is persistent. Expression is also found in the base of the lateral root suggesting an activity separate from cell division activity, perhaps involving metabolite transfer. CHEETAH is expressed within one day of germination of the seed in the radicle's meristem. Its overall pattern is similar to the aux1 gene in legumes as determined by in situ hybridizations.

CHEETAH also has three independent gus insertions and single insert lines showed that a 4.7 kb EcoRI fragment is required for activity. Flanking upstream and downstream DNA was isolated which in turn hybridized to the 4.7 kb fragment. The two flanking regions are contiguous on an Arabidopsis BAC clone, suggesting that the genomic "supermarket" of the crucifer can serve for further functional genomic analysis of nodulation and lateral root initiation and growth. Detailed analysis of this and other promoters is in progress.

A key question remains unanswered. What happens when CHEETAH is knocked out? Preliminary data suggest that most (17/18) T2 lines with gus expression are heterozygous, indicating perhaps strong selection against the homozygote (D. Lohar and J. Stiller, unpubl. data). Even stronger distortions of segregation for gus expression also occurred in FATA MORGANA as well as TIMPA, suggesting that yet unexplained mechanisms controlling gene expression in transgenic lines occur.

Lotus japonicus has demonstrated its utility for investigating genetic and biochemical processes underlying legume development and symbioses. Important tools are being developed which allow the investigation of gene systems. We can foresee the development of expression microarrays and proteomics, as well as a more complete analysis of mutant genes. Trapping and activation strategies will lead to an understanding of how genes work together in different organs. Their phylogeny will aid in extension of knowledge from model legumes to crop legumes through microsynteny.

Gene discovery is an important, yet publicly overlooked component of biotechnology. Knowledge of genes will allow our directed improvement of plants through metabolic engineering (altering oils, secondary products, phytoestrogens, etc.) as well as the engineering of plant architecture. Legumes offer a new perspective in metabolic engineering as well as pharmacological engineering because of their abundance of novel biochemical pathways such as novel hydroxylations. The combination of functional genomics, structural genomics, bioinformatics, and gene transfer technologies promises to provide crop plants with properties designed to meet the challenges of the new millennium.

We can see that a lot has been done, but more is needed. We need to establish a functional electronic network beyond the present website (http://www.psu.missouri.edu/lnl/lotusjaponicus/lj.htm).

The map needs to be more complete, and deposits of tissue-specific cDNA libraries need to be made and micro-arrayed. More transgenic lines expressing reporter genes behind tissue or process-specific promoters are required. ESTs need to be placed on the map, and regional contigs need to be generated. The application of chromosome painting to align genetic and physical maps is valuable, as is the development of a proteomics database. More tagged genes need to be isolated and understood. Studies of gene interaction is a major goal. The extent of synteny to other legumes and indeed to other plants needs to be determined.

The experimental advantages of Lotus japonicus and the strong sense of international and national cooperativity and sharing, as well as published results and related insights, will naturally draw researchers to this organism. The next few years will indeed be exciting for the nodulation community as we start to understand the processes relating to nodule induction and function, as well as its relation to other symbioses.

Thanks go to the members of my laboratory work and other colleagues for sharing unpublished results. Apologies to those whose work I either failed to mention or misrepresented; either occurred without intent. NSF and The Eppley Foundation are thanked for support.

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Signals and Signal Perception in Biotic Interactions in Plants (C3)
February 22 - February 27, 2000, Taos, New Mexico
Organizers: Richard A. Dixon and Maria J. Harrison
Early Registration: December 20, 1999
Sponsored by Monsanto Company and The Samuel Roberts Noble Foundation, Inc., Contact: Paul Lugauer, Keystone Symposia, Drawer 1630, 221 Summit Place, Unit 272, Silverthorne, CO 80498, Telephone 970-262-1230 ext. 111, Fax: 970-262-1525 FAX, E-mail: keystone@symposia.com
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