Transfer of intracolonial genetic variability through gametes in Acropora hyacinthus corals

In recent years, the new phenomenon of intracolonial genetic variability within a single coral colony has been described. This connotes that coral colonies do not necessarily consist of only a single genotype, but may contain several distinct genotypes. Harboring more than one genotype could improve survival under stressful environmental conditions, e.g., climate change. However, so far it remained unclear whether the intracolonial genetic variability of the adult coral is also present in the gametes. We investigated the occurrence of intracolonial genetic variability in 14 mature colonies of the coral Acropora hyacinthus using eight microsatellite loci. A grid was placed over each colony before spawning, and the emerging egg/sperm bundles were collected separately in each grid. The underlying tissues as well as the egg/sperm bundles were genotyped to determine whether different genotypes were present. Within the 14 mature colonies, we detected 10 colonies with more than one genotype (intracolonial genetic variability). Four out of these 10 mature colonies showed a transfer of different genotypes via the eggs to the next generation. In two out of these four cases, we found additional alleles, and in the two other cases, we found only a subset of alleles in the unfertilized eggs. Our results suggest that during reproduction of A. hyacinthus, more than one genotype per colony is able to reproduce. We discuss the occurrence of different genotypes within a single coral colony and the ability for those to release eggs which are genetically distinct.     

The Dam1 complex confers microtubule plus end–tracking activity to the Ndc80 kinetochore complex

Kinetochores must remain associated with microtubule ends, as they undergo rapid transitions between growth and shrinkage. The molecular basis for this essential activity that ensures correct chromosome segregation is unclear. In this study, we have used reconstitution of dynamic microtubules and total internal reflection fluorescence microscopy to define the functional relationship between two important budding yeast kinetochore complexes. We find that the Dam1 complex is an autonomous plus end–tracking complex. The Ndc80 complex, despite being structurally related to the general tip tracker EB1, fails to recognize growing ends efficiently. Dam1 oligomers are necessary and sufficient to recruit Ndc80 to dynamic microtubule ends, where both complexes remain continuously associated. The interaction occurs specifically in the presence of microtubules and is subject to regulation by Ipl1 phosphorylation. These findings can explain how the force harvested by Dam1 is transmitted to the rest of the kinetochore via the Ndc80 complex.     

Endophytes from wild cereals protect wheat plants from drought by alteration of physiological responses of the plants to water stress

Endophytes contribute to plant performance, especially under harsh conditions. We therefore hypothesized that wild plants have retained beneficial endophytes that are less abundant or not present in related crop plants. To test this hypothesis, we selected two endophytes that were found in Sharon goatgrass, an ancestor of wheat, and tested their effect on bread wheat. Both endophytes infected wheat and improved sustainability and performance under water-limited conditions. To determine how the endophytes modify plant development, we measured parameters of plant growth and physiological status and performed a comparative metabolomics analysis. Endophyte-treated wheat plants had reduced levels of stress damage markers and reduced accumulation of stress-adaptation metabolites. Metabolomics profiling revealed significant differences in the response to water stress of endophyte-treated plants compared with untreated plants. Our results demonstrate the potential of endophytes from wild plants for improvement of related crops and show that the beneficial effects of two endophytes are associated with alteration of physiological responses to water-limited conditions.     

Biosynthesis of the anti‐diabetic metabolite montbretin A: glucosylation of the central intermediate mini‐MbA

Type 2 diabetes (T2D) affects over 320 million people worldwide. Healthy lifestyles, improved drugs and effective nutraceuticals are different components of a response against the growing T2D epidemic. The specialized metabolite montbretin A (MbA) is being developed for treatment of T2D and obesity due to its unique pharmacological activity as a highly effective and selective inhibitor of the human pancreatic α‐amylase. MbA is an acylated flavonol glycoside found in small amounts in montbretia (Crocosmia × crocosmiiflora) corms. MbA cannot be obtained in sufficient quantities for drug development from its natural source or by chemical synthesis. To overcome these limitations through metabolic engineering, we are investigating the genes and enzymes of MbA biosynthesis. We previously reported the first three steps of MbA biosynthesis from myricetin to myricetin 3‐O‐(6′‐O‐caffeoyl)‐glucosyl rhamnoside (mini‐MbA). Here, we describe the sequence of reactions from mini‐MbA to MbA, and the discovery and characterization of the gene and enzyme responsible for the glucosylation of mini‐MbA. The UDP‐dependent glucosyltransferase CcUGT3 (UGT703E1) catalyzes the 1,2‐glucosylation of mini‐MbA to produce myricetin 3‐O‐(glucosyl‐6′‐O‐caffeoyl)‐glucosyl rhamnoside. Co‐expression of CcUGT3 with genes for myricetin and mini‐MbA biosynthesis in Nicotiana benthamiana validated its biological function and expanded the set of genes available for metabolic engineering of MbA.     

Managing the middle: A shift in conservation priorities based on the global human modification gradient

An increasing number of international initiatives aim to reconcile development with conservation. Crucial to successful implementation of these initiatives is a comprehensive understanding of the current ecological condition of landscapes and their spatial distributions. Here, we provide a cumulative measure of human modification of terrestrial lands based on modeling the physical extents of 13 anthropogenic stressors and their estimated impacts using spatially explicit global datasets with a median year of 2016. We quantified the degree of land modification and the amount and spatial configuration of low modified lands (i.e., natural areas relatively free from human alteration) across all ecoregions and biomes. We identified that fewer unmodified lands remain than previously reported and that most of the world is in a state of intermediate modification, with 52% of ecoregions classified as moderately modified. Given that these moderately modified ecoregions fall within critical land use thresholds, we propose that they warrant elevated attention and require proactive spatial planning to maintain biodiversity and ecosystem function before important environmental values are lost.     

Habitat quality and drought effects on breeding mallard and other waterfowl populations in California,USA

As many as 500,000 waterfowl reside in California, USA, during summer, but little is known about the availability or quality of their habitats. Wetland size and distribution serve as proximate cues for habitat selection by breeding waterfowl in other parts of North America such as the Prairie Pothole Region. In heavily modified landscapes such as California's Central Valley, disturbance from factors like crop cultivation and urban development may limit access, affect survival, and decrease reproductive success. Water limitations due to recurring seasonal droughts pose another potential threat to breeding waterfowl. Spatial and temporal disparities in environmental resources may provide clearer indications of ultimate habitat selection. We addressed waterfowl habitat selection in 9 regions surveyed annually by California's Department of Fish and Wildlife to determine relative importance of drought severity, wetland area, and habitat quality on mallard (Anas platyrhynchos) and other waterfowl population dynamics from 2007–2019. High-quality habitat supports long-term population persistence of waterfowl. This study period included an extended drought (2012–2015) and flooding (2016–2017). Statewide, habitat quality was the best predictor of mallard and other waterfowl population fluctuations. The model that included intermediate habitat quality, which accounted for influence of adjacent land-use, outperformed models that included wetland area alone. At the regional level, drought severity out-ranked other variables in most regions, suggesting management at regional scales must account for climate. Drought accounted for bird declines in some regions and possible increases in others. This information could be used to identify areas for conservation priority based on projected drought frequency and severity.     

Effects of biodiversity in agricultural landscapes on the protective microbiome of insects – a review

Symbiotic bacteria in herbivorous insects can have strong beneficial impacts on their host's survival, including conferring resistance to natural enemies such as parasitoid wasps or pathogens, while also imposing energetic costs on the host, resulting in cost‐benefit trade‐offs. Whether these trade‐offs favour the hosting of symbionts depends on the growth environment of the herbivore. Long‐term experimental grassland studies have shown that increasing plant species richness leads to an increased diversity of associated herbivores and their natural enemies. Such a change in natural enemy diversity, related to changes in plant diversity, could also drive changes in the community of symbionts hosted by the herbivorous insects. Aphids are one model system for studying symbionts in insects, and effects of host‐plant species and diversity on aphid‐symbiont interactions have been documented. Yet, we still understand little of the mechanisms underlying such effects. We review the current state of knowledge of how biodiversity can impact aphid‐symbiont communities and the underlying drivers. Then, we discuss this in the framework of sustainable agriculture, where increased plant biodiversity, in the form of wildflower strips, is used to recruit natural enemies to crop fields for their pest control services. Although aphid symbionts have the potential to reduce biological control effectiveness through conferring protection for the host insect, we discuss how increasing plant and natural enemy biodiversity can mitigate these effects and identify future research opportunities. Understanding how to promote beneficial interactions in ecological systems can help in the development of more sustainable agricultural management strategies.     

Reproductive isolation and the maintenance of species boundaries in two serpentine endemic Jewelflowers

Speciation occurs when reproductive barriers substantially reduce gene flow between lineages. Understanding how specific barriers contribute to reproductive isolation offers insight into the initial forces driving divergence and the evolutionary and ecological processes responsible for maintaining diversity. Here, we quantified multiple pre‐ and post‐pollination isolating barriers in a pair of closely related California Jewelflowers (Streptanthus, Brassicaceae) living in an area of sympatry. S. breweri and S. hesperidis are restricted to similar serpentine habitats; however, populations are spatially isolated at fine‐scales and rarely co‐occur in intermixed stands. Several intrinsic postzygotic barriers were among the strongest we quantified, yet, postzygotic barriers currently contribute little to overall reproductive isolation due to the cumulative strength of earlier‐acting extrinsic barriers, including spatial isolation, and flowering time and pollinator differences. Data from multiple years suggest that pre‐pollination barriers may have different strengths depending on annual environmental conditions. Similarly, crossing data suggest that the strength of intrinsic isolation may vary among different population pairs. Estimates of total reproductive isolation in S. breweri and S. hesperidis are robust to uncertainty and variability in individual barrier strength estimates, demonstrating how multiple barriers can act redundantly to prevent gene flow between close relatives living in sympatry.