Genetic differentiation and phylogenetic relationships among six Abies species from European and Turkish areas

The phylogenetic relationships of the Abies species in European and Turkish regions have frequently been an object of controversial conclusions. Therefore, we compared the genetic structures of 21 populations belonging to six Abies species which are native to  entral, eastern and south-eastern European regions and  different areas in the Turkey (Asia minor). We used the allele frequency distribution of five isozyme gene locialready showing a high discriminatory power to assess the genetic differentiation among the Abies populations. The UPGMA-dendrogram based on genetic distances showed a clear discrimination between the Turkish Abies species and A. alba from Europe. The particular allele frequency distributions at the isozyme loci PGI-A and 6PGDH-Aconfirmed a great genetic dissimilarity between A. alba and the Turkish Abies species.These results contradict the phylogenetic relationships of the Abies species postulated inother studies

Persistence of dissolved organic matter explained by molecular changes during its passage through soil

Dissolved organic matter affects fundamental biogeochemical processes in the soil such as nutrient cycling and organic matter storage. The current paradigm is that processing of dissolved organic matter converges to recalcitrant molecules (those that resist degradation) of low molecular mass and high molecular diversity through biotic and abiotic processes. Here we demonstrate that the molecular composition and properties of dissolved organic matter continuously change during soil passage and propose that this reflects a continual shifting of its sources. Using ultrahigh-resolution mass spectrometry and nuclear magnetic resonance spectroscopy, we studied the molecular changes of dissolved organic matter from the soil surface to 60 cm depth in 20 temperate grassland communities in soil type Eutric Fluvisol. Applying a semi-quantitative approach, we observed that plant-derived molecules were first broken down into molecules containing a large proportion of low-molecular-mass compounds. These low-molecular-mass compounds became less abundant during soil passage, whereas larger molecules, depleted in plant-related ligno-cellulosic structures, became more abundant. These findings indicate that the small plant-derived molecules were preferentially consumed by microorganisms and transformed into larger microbial-derived molecules. This suggests that dissolved organic matter is not intrinsically recalcitrant but instead persists in soil as a result of simultaneous consumption, transformation and formation