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18th Congress of the International Organization for Mycoplasmology, Chianciano Terme, Italy 11th – 16th July 2010
The 18th Congress of the International Organization for Mycoplasmology (IOM) took place in Chianciano Terme, Siena, Italy, with 300 delegates from 34 countries. IOM is an international organization dedicated to the study of Mollicutes; wall-less bacteria that infect and cause diseases in a wide range of animals, insects and plants. The congress organizing committee was chaired by Professor Assunta Bertaccini from the University of Bologna, and marked the first time in the history of IOM that the meeting was organized by a phytoplasmologist. Chianciano Terme is located in Toscana, a small town famous since Roman times for its thermal baths. It is surrounded by the typical Tuscan landscape of hills supporting vineyards, olive groves and beautiful evergreen cypresses. The fact that IOM joins scientists researching mycoplasmas , ureaplasmas, phytoplasmas and spiroplasmas makes IOM a unique meeting. It brings together groups of researchers working on human, vertebrate, insect and plant associated mollicutes, which means that a broad array of research techniques and outcomes are presented, providing a wealth of opportunity to enrich discussion.
An interesting feature of Mollicutes is their small A+T rich genomes. Among the smallest of all self-replicating genomes is that of Mycoplasma pneumonie which has become a focus of studies aiming to elucidate minimal genome composition, transcriptional regulation, metabolism and proteomics.
Exciting advances on this topic were presented by M. Balish (Miami University), E. Yus (Centre for Genomic Regulation-Barcelona, Spain) and V. van Noort (European Molecular Biology Laboratory, Germany) among others.
Mollicutes have also provided study models for the newly emerging science of Synthetic Genomics. Progress toward construction of a synthetic Mycoplasma mycoides cell was discussed by J. Glass from J. Craig Venter Institute Inc. (USA). Results of advances in genome synthesis and genome transplantation were presented as prerequisites to the construction of a M. mycoides cell whose genome was chemical ly synthesized and transplanted to a recipient M. capricolum cell, producing a self-replicating mol l icute. Other challenges of Mollicutes is the difficulty to grow them and the scarcity molecular tools for studying their genome function. The “Derrick Edward Award” was granted to Dr Pascal Sirand -Pugnet (INRA, Bordeaux), for strategic advances on a combination of functional a nd compar a t iv e my cop l asma genomics. He is also credited with creating the database Molligen, an useful tool for mycoplasmalogists. Prof. Patricia Totten (U. of Washington) was awarded the “Peter Hannan Award” for her contributions to the discovery, detection and molecular pathogenesis of human reproductive tract diseases associated with Mycoplasma genitalium.
Despite its limited genome of 580 kb, this bacterium establishes, generates inflammation, evades the immunological responses and persists in the host. The “Emmy Klieneberger-Nobel Award” was granted to Dr. Shigetou Namba (U. of Tokyo) in recognition of his many cont r ibut ions to understanding phytoplasma biology, particularly through the study of plant-insectphy toplasma inte r ac t i ons and pathogenicity. The most significant piece of his work has been elucidation of the first complete genome sequence of a phytoplasma, providing new information about metabolic capabilities and a platform for comparative and functional genomics of these parasites.
His studies also revealed the importance of mobile genetic elements as inducers of genome variability and the importance of extrachromosomal DNAs (plasmids) in insect vector transmissibility of phytoplasmas. Most recently, Dr . Namba has also characterized a new protein (TENGU) secreted by Onion Yellows (OY) phytoplasma and its role as a pathogenicity factor in diseased plants.
Some very exciting new results of relevance to phytoplasmologists were presented during the congress. Using different approaches, two groups have been studying the onset of symptoms in phytoplasma diseased plants. G. Firrao’s group (U. of Udine, Italy) inoculated different phytoplasma strains into Arabidopsis thaliana at various developmental stages. The type and severity of resulting symptoms suggested that the concurrency of meristem development with infection is a major determinant of symptom pat tern. Phy toplasma induc ed deregulation of SEPALLATA plant genes was observed. A. Hoshi (U. of Tokyo) presented evidence of the recognition of a virulence factor from OY phytoplasma which causes alteration to plant architecture. A group of candidate phytoplasma proteins that are secreted within infected plants were expressed in Nicotiana benthamiana plants, and resulting changes in plant morphology were evaluated. The protein TENGU was implicated in the induction of witches’ brooms and dwarfism in plants, suggesting that i t is par tial ly responsible for symptoms that developed on these hosts.
On the topic of insect vectors, efforts to define the proteins responsible for phytoplasma-vector interactions were presented. Evidence was obtained by X. Foissac’s group (INRA and U. of Bordeaux) that different variants of phytoplasma transmembrane proteins (VMP) of Stolbur and Flavescence Doree phytoplasmas correlated with the transmission by different insect species or ecotypes. A. Sugio (John Innes Centre, UK) suggested that SAP11 is another virulence factor candidate.
SAP11 is also involved in the increase of fecundity of vector Macrosteles quadrilineatus and was shown to interact with Arabidopsis transcription factors involved in generation of crinkled leaves and numerous stems. L. Galetto (Torino, Italy) showed that phytoplasma membrane protein Amp interacts with insect vector proteins identified as actin and ATP synthase a and b subunits, present in the gut epithelium of vector species. No evidence of these interactions was observed on non vector species.
Of special interest were results of axenic in vitro growth of phytoplasmas, presented by A. Bertaccini’s group.
Phytoplasma infected Catharanthus roseus (periwinkle) shoots were cut from sterile, micropropagated plantlets and incubated in “Mycoplasma Experience” liquid medium (a medium for mycoplasmas containing pig serum, a broth base and yeast extract). After a prolonged incubation, plant-free aliquots of the liquid medium were transferred to new medium and incubated further. Acidification of the medium and PCR results suggested in vitro growth of phytoplasmas had occurred.
Finally, I would like to compliment the excellent organization of the congress, the diverse selection of invited speakers and the many opportunities to socialize and interact with other scientists. The social events included a welcome cocktail, a wine tasting and dinner buffet in the beautiful vineyard “Tenuta Rocca di Montemassi” and a spectacular congress dinner at one of the most famous spas of the region called Parco Acqua Santa. All these activities were surrounded by the fantastic Tuscan landscape and accompanied by the delicious local food and wine, making it an experience from every point of view.
The congress dinner included the closing ceremony whereby the head of the French delegation formally accepted the responsibility of hosting the next congress in Toulouse, France in 2012.
Liliana Franco-Lara Universidad Militar Nueva Granada, Bogota-Colombia