Background: Sex chromosomes have arisen independently in a wide variety of species, yet they share common characteristics, including the presence of suppressed recombination surrounding sex determination loci. Mammalian sex chromosomes contain multiple palindromic repeats across the non-recombining region that show sequence conservation through gene conversion and contain genes that are crucial for sexual reproduction. In plants, it is not clear if palindromic repeats play a role in maintaining sequence conservation in the absence of homologous recombination.Results: Here we present the first evidence of large palindromic structures in a plant sex chromosome, based on a highly contiguous assembly of the W chromosome of the dioecious shrubSalix purpurea. The W chromosome has an expanded number of genes due to transpositions from autosomes. It also contains two consecutive palindromes that span a region of 200 kb, with conspicuous 20-kb stretches of highly conserved sequences among the four arms that show evidence of gene conversion. Four genes in the palindrome are homologous to genes in the sex determination regions of the closely related genusPopulus, which is located on a different chromosome. These genes show distinct, floral-biased expression patterns compared to paralogous copies on autosomes.Conclusion: The presence of palindromes in sex chromosomes of mammals and plants highlights the intrinsic importance of these features in adaptive evolution in the absence of recombination. Convergent evolution is driving both the independent establishment of sex chromosomes as well as their fine-scale sequence structure.

36 p.-5 fig.-1 tab.New lignin-degrading microorganisms and their enzymes can contribute to more efficient and environmentally sound use of lignocellulosic biomass in future biorefineries. In view ofthis, 127 endophytic fungi were isolated from eucalyptus trees. Strains were tested for their ability to produce ligninolytic enzymes in agar-plate medium containing ABTS, and 21 showed positive ABTS-oxidation. Positive strains in liquid\ud medium confirmed that five produced laccase but no peroxidase activity. These strains were identified as Hormonema sp. and Pringsheimia smilacis, of the family Dothioraceae, Ulocladium sp. (Pleosporaceae) and Neofusicoccum luteum and Neofusicoccum australe (Botryosphaeriaceae). Laccase production by fungi of the family Dothioraceae is described here for the first time.To increase laccase production from these fungi, copper sulphate and ethanol were assayed as inducers. An increase in laccase activity of 85% was found for Hormonema sp. and N. luteum and 95% for N. australe. No increase was obtained for P. smilacis. A maximum temperature of 40 ◦C is recommended for possible biotechnological applications with these four strains at pH 2 for N. luteum and N. australe, pH 4 for Hormonema sp. and pH 4–5 for P. smilacis.The authors wish to thank the Spanish Ministry of Economy and Competitiveness (MINECO) for funding this study via Projects\ud CTQ 2011-28503-C02-01, CTQ2011-28503-C02-02 and CTQ2013-\ud 47158-R and Programme PTA 2011-4857-I.Peer reviewe

There is an increasing need to calibrate microbial community profiles obtained through next generation sequencing (NGS) with relevant taxonomic identities of the microbes, and to further associate these identities with phenotypic attributes. Phenotype Microarray (PM) techniques provide a semi-high throughput assay for characterization and monitoring the microbial cellular phenotypes. Here, we present detailed descriptions of two different PM protocols used in our recent studies on fungal endophytes of forest trees, and highlight the benefits and limitations of this technique. We found that the PM approach enables effective screening of substrate utilization by endophytes. However, the technical limitations are multifaceted and the interpretation of the PM data challenging. For the best result, we recommend that the growth conditions for the fungi are carefully standardized. In addition, rigorous replication and control strategies should be employed whether using pre-configured, commercial microwell-plates or in-house designed PM plates for targeted substrate analyses. With these precautions, the PM technique is a valuable tool to characterize the metabolic capabilities of individual endophyte isolates, or successional endophyte communities identified by NGS, allowing a functional interpretation of the taxonomic data. Thus, PM approaches can provide valuable complementary information for NGS studies of fungal endophytes in forest trees.