CORRECTION: The Cytochrome b6f Complex is not Involved in Cyanobacterial State Transitions

Photosynthetic organisms must sense and respond to fluctuating environmental conditions in order to perform efficient photosynthesis and to avoid the formation of dangerous reactive oxygen species. The excitation energy arriving at each photosystem permanently changes due to variations in the intensity and spectral properties of the absorbed light. Cyanobacteria, like plants and algae, have developed a mechanism, named "state transitions," that balances photosystem activities. Here, we characterize the role of the cytochrome b(6)f complex and phosphorylation reactions in cyanobacterial state transitions using Synechococcus elongatus PCC 7942 and Synechocystis PCC 6803 as model organisms. First, large photosystem II (PSII) fluorescence quenching was observed in State II, a result that does not appear to be related to energy transfer from PSII to PSI (spillover). This membrane-associated process was inhibited by betaine, Suc, and high concentrations of phosphate. Then, using different chemicals affecting the plastoquinone pool redox state and cytochrome b(6)f activity, we demonstrate that this complex is not involved in state transitions in S. elongatus or Synechocystis PCC6803. Finally, by constructing and characterizing 21 protein kinase and phosphatase mutants and using chemical inhibitors, we demonstrate that phosphorylation reactions are not essential for cyanobacterial state transitions. Thus, signal transduction is completely different in cyanobacterial and plant (green alga) state transitions

LOTUS spp: BIOTECHNOLOGICAL STRATEGIES TO IMPROVE THE BIOECONOMY OF LOWLANDS IN THE SALADO RIVER BASIN (ARGENTINA)

The Salado River Basin region is the most important livestock breeding area inArgentina, wherethe Lotus species has been traditionally cultivated as forages.Nearly 60% of their land surface is dominated by salt-affected soils with severeconstraints for crop cultivation. In order to cope with that limitation, farmers haveutilized species such as non-native L. tenuis (ex- Lotus glaber), which shows a verygood adaptation. As a result, inter-seeding of L. tenuis has been proposed as astrategy of choice for improving forage production in marginal areas. The increasein soil quality by these means is achieved by an increment of the organic mattercontent, improvement of soil fertility as well as microbial biodiversity. Thus, theintroduction of L. tenuis and/or other Lotus genotypes could have enormousbenefits for similar constrained lands around the world. We are developing anintegrated analysis of the changes that occur in soils under legume production. Wewill not only analyze the microbial diversity associated, but also soil physical andchemical characteristics and the impact of different legume-microbes associationon mitigation of GHG emissions. In addition, we are identifying the main geneticdeterminants associated with interesting agronomic traits such as plant toleranceagainst biotic and abiotic stresses and the content of condensed tannins. Our futureand present research will build a solid base for the improvement of agronomicallyimportantspecies and the development of better strategies for the management ofconstrained lands such as the lowlands in the Argentinean Pampas