A tufA metabarcoding approach for Ulva and related seaweeds

Ulva-like green algae are notoriously difficult to distinguish due to their morphological variability and/or similarity. DNA barcoding approaches are therefore currently essential for their reliable identification. However, such approaches often fail when rare or inconspicuous species are to be detected in large mixed populations of Ulva species, for example, at early stages following the introduction of species into new habitats. We therefore developed a detection method based on next-generation DNA sequencing. The approach is suitable for the analysis of DNA traces in preserved water samples or in particles enriched by filtration from such samples. A new pair of primers was designed to amplify a 475 bp segment within the tufA marker gene. The primers were relatively group specific. 68.5% of all reads obtained after quality filtering represented the genus Ulva, 11.1% other Ulvophyceae, and only 20% other Chlorophyta, despite their relatively higher abundance in phytoplankton. The relatively short target amplicon still allows good differentiation of Ulvales and Ulothrichales at the species level. Using a database containing tufA sequences of 879 species - 281 of which were Ulvophyceae and 35 Ulva - we were able to detect mostly Ulvophyceae that had been previously detected in our study area in northern Germany using Sanger sequencing. However, the number of species detected at individual sites was generally higher than in previous studies, which could be due to drifting DNA: Analysis of samples collected at different distances from shore suggests that a sample collected at a given site may be influenced by Ulvophyceae within a radius of up to about 1 km in winter. In summer, this radius is reduced to less than 100 m, possibly due to the less frequent occurrence of strong wind events. Nonetheless, rare species may be detected with this new approach: At one site, an undescribed Blidingia species that was not previously known from our study area was repeatedly detected. Based on these findings, the species was searched for and found, and its identity confirmed by traditional tufA barcoding

High Diversity of Cytospora Associated With Canker and Dieback of Rosaceae in China, With 10 New Species Described

Cytospora canker is a destructive disease of numerous hosts and causes serious economic losses with a worldwide distribution. Identification of Cytospora species is difficult due to insufficient phylogenetic understanding and overlapped morphological characteristics. In this study, we provide an assessment of 23 Cytospora spp., which covered nine genera of Rosaceae, and focus on 13 species associated with symptomatic branch or twig canker and dieback disease in China. Through morphological observation and multilocus phylogeny of internal transcribed spacer (ITS), large nuclear ribosomal RNA subunit (LSU), actin (act), RNA polymerase II subunit (rpb2), translation elongation factor 1-α (tef1-α), and beta-tubulin (tub2) gene regions, the results indicate 13 distinct lineages with high branch support. These include 10 new Cytospora species, i.e., C. cinnamomea, C. cotoneastricola, C. mali-spectabilis, C. ochracea, C. olivacea, C. pruni-mume, C. rosicola, C. sorbina, C. tibetensis, and C. xinjiangensis and three known taxa including Cytospora erumpens, C. leucostoma, and C. parasitica. This study provides an initial understanding of the taxonomy of Cytospora associated with canker and dieback disease of Rosaceae in China

DAM pilot project: Exclusion of bottom trawl fishery in marine protected areas of the German EEZ (North Sea) - DAM MPA Geo 1, Cruise No. HE588, October 24 - November 4, 2021, Bremerhaven (Germany) - Bremerhaven (Germany)

During HE588, data were collected in five research areas in the south-eastern part of the German Bight as part of the DAM Pilotmission on the exclusion of mobile bottom-contact fishing in the North Sea (www.mgf-nordsee.de). The cruise started on October 24, 2021, and had a duration of twelve days at sea. The conducted tasks consisted of seafloor mapping with hydroacoustic devices, multicoring and grab sampling from the seafloor surface, lander deployments for the study of current characteristics, and video and diving surveys of benthic fauna. Despite the unstable weather conditions, all scientific tasks could be conducted successfully within the allocated time

Cytospora elaeagnicola sp. nov. Associated with Narrow-leaved Oleaster Canker Disease in China

Cytospora is a genus including important phytopathogens causing severe dieback and canker diseases distributed worldwide with a wide host range. However, identification of Cytospora species is difficult since the currently available DNA sequence data are insufficient. Aside the limited availability of ex-type sequence data, most of the genetic work is only based on the ITS region DNA marker which lacks the resolution to delineate to the species level in Cytospora. In this study, three fresh strains were isolated from the symptomatic branches of Elaeagnus angustifolia in Xinjiang Uygur Autonomous Region, China. Morphological observation and multi-locus phylogenetic analyses (ITS, LSU, ACT and RPB2) support these specimens are best accommodated as a distinct novel species of Cytospora. Cytospora elaeagnicola sp. nov. is introduced, having discoid, nearly flat, pycnidial conidiomata with hyaline, allantoid conidia, and differs from its relatives genetically and by host association

How do microbiota associated with an invasive seaweed vary across scales?

Communities are shaped by scale dependent processes. To study the diversity and variation of microbial communities across scales, the invasive and widespread seaweed Agarophyton vermiculophyllum presents a unique opportunity. We characterized pro‐ and eukaryotic communities associated with this holobiont across its known distribution range, which stretches over the northern hemisphere. Our data reveal that community composition and diversity in the holobiont vary at local but also larger geographic scales. While processes acting at the local scale (i.e., within population) are the main structuring drivers of associated microbial communities, changes in community composition also depend on processes acting at larger geographic scales. Interestingly, the largest analysed scale (i.e., native and non‐native ranges) explained variation in the prevalence of predicted functional groups, which could suggest a functional shift in microbiota occurred over the course of the invasion process. While high variability in microbiota at the local scale supports A. vermiculophyllum to be a generalist host, we also identified a number of core taxa. These geographically independent holobiont members imply that cointroduction of specific microbiota may have additionally promoted the invasion process

Host Promiscuity Promotes Invasiveness of the Rhodophyte Agarophyton Vermiculophyllum

Invasive species are holobionts and during the invasion process they are accompanied by associated microbiota. In the course of the introduction process extreme conditions during transport and exposure to different conditions in a novel environment may induce holobiont disturbance. Upon introduction, the macroalgal holobiont interacts with microbiota from the new environment and reconfigures new functional microbial communities. As not all microbes may have survived, microbiota from the new environment may replace certain microbes from the native environment. Therefore, flexibility of the seaweed host towards environmental microbiota –or host promiscuity– may be an important trait in macroalgal invasions. Here, we simulated an introduction event in an experimental setting, using the invasive macroalga Agarophyton vermiculophyllum as a model. Individuals from geographically distant populations were transplanted to a common garden in the lab and subjected to a holobiont disturbance treatment followed by exposure to a new source of microbes. This treatment induced strong changes in associated microbiota, which shifted irreversibly in terms of composition and diversity, but recovered functionally in most respects. Moreover, beta-diversity strongly decreased in treated holobionts, indicating that different populations configured more common microbial communities in the common garden. In non-native populations this decline was more rapid and more pronounced, while microbial communities of native populations remained more similar to communities observed in the field. These results demonstrate that non-native A. vermiculophyllum are more flexible to environmental microbes, suggesting that an intra-specific increase in host promiscuity may have promoted the invasion process of A. vermiculophyllum

Draft genome and description of Waterburya agarophytonicola gen. nov. sp. nov. (Pleurocapsales, Cyanobacteria): a seaweed symbiont

This work introduces Waterburya agarophytonicola Bonthond and Shalygin gen. nov., sp. nov, a baeocyte producing cyanobacterium that was isolated from the rhodophyte Agarophyton vermiculophyllum (Ohmi) Gurgel et al., an invasive seaweed that has spread across the northern hemisphere. The new species genome reveals a diverse repertoire of chemotaxis and adhesion related genes, including genes coding for type IV pili assembly proteins and a high number of genes coding for filamentous hemagglutinin family (FHA) proteins. Among a genetic basis for the synthesis of siderophores, carotenoids and numerous vitamins, W. agarophytonicola is potentially capable of producing cobalamin (vitamin B-12), for which A. vermiculophyllum is an auxotroph. With a taxonomic description of the genus and species and a draft genome, this study provides as a basis for future research, to uncover the nature of this geographically independent association between seaweed and cyanobiont

Diaporthalean fungi associated with canker and dieback of trees from Mount Dongling in Beijing, China

Volume: 59Start Page: 67-9

Detection of Ulva SPP. and related species with better resolution: a tufa metabarcoding approach for Ulvophyceae

Ulva-like green algae are notoriously difficult to distinguish because of their great morphological variability and/or similarity, and DNA barcoding approaches are currently indispensable for their identification. However, such approaches often fail if rare or inapparent species are to be detected in large mixed green algal stands. We therefore developed a detection method based on next generation DNA sequencing, suitable for analysis of DNA traces in conserved water samples. A primer pair was developed that allows for amplification of a 475 bp long section within the tufA marker gene. The primers are relatively group specific, as 79.6 % of all reads obtained after quality filtering represented Ulvophyceae. The relatively short target amplicon still allows for good differentiation of Ulvales and Ulothrichales at the species level. Using a database containing tufA sequences of 879 species – thereof 281 Ulvophyceae – we detected predominantly species that were previously observed in our study area in Northern Germany. However, the number of species detected in single sites was generally higher than in earlier barcoding studies, which may be due to drifting genetic traces: Samples collected offshore appeared influenced by Ulvophyceae present within a radius of up to about 1 km in winter and less than 100 m in summer. Nonetheless, this new approach can be used to detect rare species: In one site an undescribed Blidingia species not yet known from our study area was repeatedly detected. Based on these findings the species was discovered and its identity was confirmed by traditional tufA barcoding