Evolution and Functional Diversification of Fructose Bisphosphate Aldolase Genes in Photosynthetic Marine Diatoms

Diatoms and other chlorophyll-c containing, or chromalveolate, algae are among the most productive and diverse phytoplankton in the ocean. Evolutionarily, chlorophyll-c algae are linked through common, although not necessarily monophyletic, acquisition of plastid endosymbionts of red as well as most likely green algal origin. There is also strong evidence for a relatively high level of lineage-specific bacterial gene acquisition within chromalveolates. Therefore, analyses of gene content and derivation in chromalveolate taxa have indicated particularly diverse origins of their overall gene repertoire. As a single group of functionally related enzymes spanning two distinct gene families, fructose 1,6-bisphosphate aldolases (FBAs) illustrate the influence on core biochemical pathways of specific evolutionary associations among diatoms and other chromalveolates with various plastid-bearing and bacterial endosymbionts. Protein localization and activity, gene expression, and phylogenetic analyses indicate that the pennate diatom Phaeodactylum tricornutum contains five FBA genes with very little overall functional overlap. Three P. tricornutum FBAs, one class I and two class II, are plastid localized, and each appears to have a distinct evolutionary origin as well as function. Class I plastid FBA appears to have been acquired by chromalveolates from a red algal endosymbiont, whereas one copy of class II plastid FBA is likely to have originated from an ancient green algal endosymbiont. The other copy appears to be the result of a chromalveolate-specific gene duplication. Plastid FBA I and chromalveolate-specific class II plastid FBA are localized in the pyrenoid region of the chloroplast where they are associated with β-carbonic anhydrase, which is known to play a significant role in regulation of the diatom carbon concentrating mechanism. The two pyrenoid-associated FBAs are distinguished by contrasting gene expression profiles under nutrient limiting compared with optimal CO2 fixation conditions, suggestive of a distinct specialized function for each. Cytosolically localized FBAs in P. tricornutum likely play a role in glycolysis and cytoskeleton function and seem to have originated from the stramenopile host cell and from diatom-specific bacterial gene transfer, respectively

Adaptació al canvi climàtic en el sector agrícola de l’Alt Pirineu i l’Aran: riscos i oportunitats

El presente estudio analiza las implicaciones del cambio climático en la agricultura de una región mediterránea montañosa modelando la idoneidad agroclimática de los cultivos y comparando el escenario climático de referencia (1971-2000) con un escenario futuro (2031-2050). Se propone una estrategia de adaptación para las 53.535 ha de campos de cultivo de la zona de estudio, con el fin de diversificar la producción agrícola manteniendo la cabaña ganadera actual. Los resultados indican que, si no se realizan cambios estructurales, los impactos del cambio climático sobre la agricultura de la zona pueden provocar una reducción de los ingresos del 9 %. Sin embargo, si esa amenaza se utiliza como motor de cambio para promover el pastoreo en prados alpinos y bosques y pastos de menor altitud, casi la mitad de las tierras agrícolas pueden ser liberadas para nuevos cultivos, que se podrían destinar al consumo humano. Esta estrategia podría generar un aumento de los ingresos brutos agrícolas en torno al 115 % (pasando de 85 a 181 millones de euros).This study analyses the implications of climate change in agriculture in a mountainous Mediterranean region by modelling crop agro-climatic suitability and comparing the reference climate scenario (1971-2000) with a future scenario (2031-2050). An adaptation strategy is proposed for the 53,535 hectares of farmland in the area under study, in order to diversify agricultural production while maintaining current livestock numbers. The results indicate that, if structural changes are not made, climate change impacts on agriculture in the area might lead to a revenue reduction of 9 %. However, if this threat is used as a driving force for change to promote grazing of alpine grasslands and lower-altitude forests and prairies, nearly half of agricultural lands may be released for new crops that could be targeted to human consumption. This strategy could generate an increase of agricultural gross revenues of about 115 % (rising from €85 million to €181 million).Aquest estudi analitza les implicacions del canvi climàtic en l’agricultura d’una regió mediterrània muntanyosa modelant la idoneïtat agroclimàtica dels cultius i comparant l’escenari climàtic de referència (1971-2000) amb un escenari futur (2031-2050). Es proposa una estratègia d’adaptació per a les 53.535 ha de camps de conreu de la zona d’estudi, per tal de diversificar la producció agrícola tot mantenint la cabana ramadera actual. Els resultats indiquen que, si no es fan canvis estructurals, els impactes del canvi climàtic sobre l’agricultura de la zona poden provocar una reducció dels ingressos del 9 %. No obstant això, si aquesta amenaça s’utilitza com a motor de canvi per a promoure la pastura de prats alpins i els boscos i praderies de menys altitud, gairebé la meitat de les terres agrícoles poden ser alliberades per a cultius nous, que es podrien destinar al consum humà. Aquesta estratègia podria generar un augment dels ingressos bruts agrícoles d’un 115 % (passarien de 85 a 181 milions d’euros)

Comparative Genomics of the Pennate Diatom Phaeodactylum tricornutum

Diatoms are one of the most important constituents of phytoplankton communities in aquatic environments, but in spite of this, only recently have large-scale diatom-sequencing projects been undertaken. With the genome of the centric species Thalassiosira pseudonana available since mid-2004, accumulating sequence information for a pennate model species appears a natural subsequent aim. We have generated over 12,000 expressed sequence tags (ESTs) from the pennate diatom Phaeodactylum tricornutum, and upon assembly into a nonredundant set, 5,108 sequences were obtained. Significant similarity (E < 1E-04) to entries in the GenBank nonredundant protein database, the COG profile database, and the Pfam protein domains database were detected, respectively, in 45.0%, 21.5%, and 37.1% of the nonredundant collection of sequences. This information was employed to functionally annotate the P. tricornutum nonredundant set and to create an internet-accessible queryable diatom EST database. The nonredundant collection was then compared to the putative complete proteomes of the green alga Chlamydomonas reinhardtii, the red alga Cyanidioschyzon merolae, and the centric diatom T. pseudonana. A number of intriguing differences were identified between the pennate and the centric diatoms concerning activities of relevance for general cell metabolism, e.g. genes involved in carbon-concentrating mechanisms, cytosolic acetyl-Coenzyme A production, and fructose-1,6-bisphosphate metabolism. Finally, codon usage and utilization of C and G relative to gene expression (as measured by EST redundance) were studied, and preferences for utilization of C and CpG doublets were noted among the P. tricornutum EST coding sequences

Modelling the impacts of climate change on potential cultivation area and water deficit in five Mediterranean crops

Aim of study: To assess the impacts of climate change on local agriculture with a high resolution in a Mediterranean region with a diversity of climates. Area of study: Catalonia (NE Spain). Material and methods: Based on historical meteorological records and a regionalization of the RCP4.5 model created by the Catalan Meteorological Service, the Papadakis agro-climate classification was calculated for two climate scenarios. The changes in agro-climatic suitability and irrigation needs of five typical Mediterranean crops (alfalfa, almond, barley, olive and orange) were analysed.  Main results: In the 2031-2050 climate scenario, over 15% of the study area will no longer be adequate for non-irrigated almond or olive, at locations in which they have been traditionally rainfed crops. If irrigation is provided, orange is likely to become agro-climatically suited for the entire Catalan coastline. Were the current crop distribution maintained, irrigation needs may increase on average 16% in the study area in the future scenario. Research highlights: High-resolution GIS data may be combined with Papadakis’ classical method to compare different climate scenarios and detect risks and opportunities for local and regional agriculture

Modelling the impacts of climate change on potential cultivation area and water deficit in five Mediterranean crops

Aim of study: To assess the impacts of climate change on local agriculture with a high resolution in a Mediterranean region with a diversity of climates.Area of study: Catalonia (NE Spain).Material and methods: Based on historical meteorological records and a regionalization of the RCP4.5 model created by the Catalan Meteorological Service, the Papadakis agro-climate classification was calculated for two climate scenarios. The changes in agro-climatic suitability and irrigation needs of five typical Mediterranean crops (alfalfa, almond, barley, olive and orange) were analysed. Main results: In the 2031-2050 climate scenario, over 15% of the study area will no longer be adequate for non-irrigated almond or olive, at locations in which they have been traditionally rainfed crops. If irrigation is provided, orange is likely to become agro-climatically suited for the entire Catalan coastline. Were the current crop distribution maintained, irrigation needs may increase on average 16% in the study area in the future scenario.Research highlights: High-resolution GIS data may be combined with Papadakis’ classical method to compare different climate scenarios and detect risks and opportunities for local and regional agriculture

Identification and comparative genomic analysis of signaling and regulatory components in the diatom Thalassiosira pseudonana

Diatoms are unicellular brown algae that likely arose from the endocytobiosis of a red alga into a single-celled heterotroph and that constitute an algal class of major importance in phytoplankton communities around the globe. The first whole-genome sequence from a diatom species, Thalassiosira pseudonana Hasle et Heimdal, was recently reported, and features that are central to diatom physiology and ecology, such as silicon and nitrogen metabolism, iron uptake, and carbon concentration mechanisms, were described. Following this initial study, the basic cellular systems controlling cell signaling, gene expression, cytoskeletal structures, and response to stress have been cataloged in an attempt to obtain a global view of the molecular foundations that sustain such an ecologically successful group of organisms. Comparative analysis with several microbial, plant, and metazoan complete genome sequences allowed the identification of putative membrane receptors, signaling proteins, and other components of central interest to diatom ecophysiology and evolution. Thalassiosira pseudonana likely perceives light through a novel phytochrome and several cryptochrome photoreceptors; it may lack the conserved RHO small-GTPase subfamily of cell-polarity regulators, despite undergoing polarized cell-wall synthesis; and it possesses an unusually large number of heat-shock transcription factors, which may indicate the central importance of transcriptional responses to environmental stress. The availability of the complete gene repertoire will permit a detailed biochemical and genetic analysis of how diatoms prosper in aquatic environments and will contribute to the understanding of eukaryotic evolution