Annual dune plant communities in the Southwest coast of Europe

This study presents an updated sintaxonomic review of the annual communities from coastal dunes in the Southwest coast of Europe, specifically in the Iberian Peninsula, including both types: directly influenced by the sea salt spray and not affected by this influence. The floristic segregation of the different plant associations was obtained by statistical agglomerative processes (UPGMA, Unweighted Pair Group Method with Arithmetic Mean) plus principal coordinate analysis (PCoA) and discussed based on the interpretation of phytosociological tables. Three new communities in central western Portugal were found and are described: Pseudorlayo minusculae-Polycarpietum alsinifoli, Cerastio diffusae-Vulpietum fontqueranae and Omphalodo kunzinskyanae-Evacietum ramosissimae

Responses to salt stress in Juncus acutus and J. maritimus during seed germination and vegetative plant growth

[EN] Responses to increasing salinity, during seed germination and vegetative plant growth, were studied in two related species of Juncus, J. maritimus and J. acutus. In both species, germination was optimal in the absence of salt, reduced by about 50% in the presence of 200 mM NaCl, and completely inhibited by NaCl concentrations above 300 mM. Previous exposure of the seeds to salt, up to 500 mM NaCl, did not affect the germination capacity in J. acutus, and clearly enhanced it in J. maritimus. A concentration-dependent inhibition of plant growth was observed in the presence of NaCl for both species, together with the parallel accumulation of sodium ions in the leaves, as determined by cation exchange HPLC. Regarding the levels of divalent cations, in J. acutus Ca2+ and Mg2+ increased up to about two-fold in plants treated with 500 mM NaCl, as compared to control plants, whereas in J. maritimus they were three-to four-fold higher than in J. acutus in the absence of salt, and did not change significantly with increasing NaCl concentrations. These results suggest that Ca2+ and Mg2+ participate in defence mechanisms against salt stress, which would be constitutive in J. maritimus and salt-inducible in J. acutus.Boscaiu Neagu, MT.; Ballesteros Amat, G.; Naranjo Olivero, MA.; Vicente Meana, Ó.; Boira Tortajada, H. (2011). Responses to salt stress in Juncus acutus and J. maritimus during seed germination and vegetative plant growth. Plant Biosystems. 145(4):770-777. doi:10.1080/11263504.2011.628446S770777145

Morphological and molecular analysis of natural hybrids between the diploid Centaurea aspera L. and the tetraploid C. seridis L. (Compositae)

[EN] Polyploidy and hybridisation are the basis of the evolution of Centaurea (Compositae). At the El Saler dune field (eastern Spain), the diploid Centaurea aspera ssp. stenophylla and the tetraploid C. seridis ssp. maritima form a polyploid complex in which C. x subdecurrens individuals occur. This polyploid complex was analysed morphologically and genetically, using random amplified polymorphic DNA (RAPD) and tubulin-based polymorphism (TBP) markers. Flow cytometry showed that the hybrids are triploid, which is a rare finding in Centaurea. Morphologically, in contrast to leaf characters, flowering characters clearly discriminated the three taxa. The genetic analyses confirm that C. x subdecurrens is a result of the hybridisation between Centaurea aspera ssp. stenophylla and C. seridis ssp. maritima, and suggest that backcrossing events and gene flow are very rare or absent. Although the hybrids likely represent true F1 offspring, they displayed some genetic diversity that is probably due to the combination of alleles. Genetic diversity was higher in diploid than in tetraploid individuals. This fact, and the high degree of sterility of the triploid hybrids, may reflect a cytotype minority exclusion effect. This may cause spatial segregation, which effectively takes place in the study area. Dune disturbance may lead to an overlapping of the parents' distribution areas, facilitating hybridisation.This work is posthumously dedicated to Antonio Samo Lumbreras, to whom we are very grateful for all his help. This study was sponsored by the Valencian Government (Research Project GVPRE/2008/130) and the Universitat Politecnica de Valencia (Research Project Ref. 3241).Ferriol Molina, M.; Garmendia, A.; Ruiz, J.; Merle Farinós, HB.; Boira Tortajada, H. (2012). Morphological and molecular analysis of natural hybrids between the diploid Centaurea aspera L. and the tetraploid C. seridis L. (Compositae). Plant Biosystems. 146(1):86-100. https://doi.org/10.1080/11263504.2012.727878S86100146

Vegetación potencial de la provincia de Granada (Trabajo)

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