Colletotrichum higginsianum extracellular LysM proteins play dual roles in appressorial function and suppression of chitin-triggered plant immunity

<p>The genome of the hemibiotrophic anthracnose fungus, Colletotrichum higginsianum, encodes a large repertoire of candidate-secreted effectors containing LysM domains, but the role of such proteins in the pathogenicity of any Colletotrichum species is unknown. Here, we characterized the function of two effectors, ChELP1 and ChELP2, which are transcriptionally activated during the initial intracellular biotrophic phase of infection. Using immunocytochemistry, we found that ChELP2 is concentrated on the surface of bulbous biotrophic hyphae at the interface with living host cells but is absent from filamentous necrotrophic hyphae. We show that recombinant ChELP1 and ChELP2 bind chitin and chitin oligomers in vitro with high affinity and specificity and that both proteins suppress the chitin-triggered activation of two immune-related plant mitogen-activated protein kinases in the host Arabidopsis. Using RNAi-mediated gene silencing, we found that ChELP1 and ChELP2 are essential for fungal virulence and appressorium-mediated penetration of both Arabidopsis epidermal cells and cellophane membranes in vitro. The findings suggest a dual role for these LysM proteins as effectors for suppressing chitin-triggered immunity and as proteins required for appressorium function.</p

A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants

New insights on subsurface energy resources in the Southern North Sea Basin area

The Southern North Sea Basin area, stretching from the UK to the Netherlands, has a rich hydrocarbon exploration and production history. The past, present and expected future hydrocarbon and geothermal exploration trends in this area are discussed for eight key lithostratigraphic intervals, ranging from the Lower Carboniferous to Cenozoic. In the period between 2007 and 2017, a total of 95 new hydrocarbon fields were discovered, particularly in Upper Carboniferous, Rotliegend and Triassic reservoirs. Nineteen geothermal systems were discovered in the Netherlands onshore, mainly targeting aquifers in the Rotliegend and Upper Jurassic/Lower Cretaceous formations. Although the Southern North Sea Basin area is mature in terms of hydrocarbon exploration, it is shown that with existing and new geological insights, additional energy resources are still being proven in new plays such as the basal Upper Rotliegend (Ruby discovery) for natural gas and a new Chalk play for oil. It is predicted that hydrocarbon exploration in the Southern North Sea Basin area will probably experience a slight growth in the coming decade before slowing down, as the energy transition further matures. Geothermal exploration is expected to continue growing in the Netherlands onshore as well as gain more momentum in the UK

The Carboniferous of the Netherlands and surrounding areas; a basin analysis. Geologica Ultraiectina (294)

This thesis deals with several aspects related to the Carboniferous of the Netherlands and surrounding areas. In the first part, the tectonic setting and sedimentary infill of the Northwest European Carboniferous Basin (NWECB, running from the United Kingdom to Poland) are illustrated by palaeogeographical maps and well correlation panels. As such, the reader is introduced into the other chapters which focus on more specific research questions related the Carboniferous in the study area. Due to deep burial, the Lower Carboniferous is very poorly known in the central part of the NWECB (northern part of the Netherlands and adjacent areas). Using high-quality 3D seismic data, it was now possible to show that Early Carboniferous carbonate platforms are present in the central part of the NWECB. A model is proposed in which carbonate platforms are limited to structural highs while in intervening graben areas deep-water sediments accummulated. In general, the Late Carboniferous is characterised by siliciclastic sedimentation. In northern England, it is proposed that sedimentation took place at varying basin-water salinities (marine-lacustrine). Cores obtained from this area have been sampled and analysed for major and trace elements. Based on these data, it is suggested that the basin essentially remained marine. The succession of Upper Carboniferous siliciclastic sediments is very thick in major parts of the NWECB. In this thesis, it is investigated which subsidence mechanisms were responsible for the accommodation of these sediments. Simple modelling experiments showed that the conventional mechanisms (flexural subsidence and thermal subsidence, following an Early Carboniferous rifting event) cannot account for the total observed subsidence. Some additional mechanisms (dynamic subsidence, intra-plate stress) or another phase of extension (rifting) are proposed. The Westphalian of the NWECB is characterised by fluvial-lacustrine deposits. Marine bands can be found intercalated in this succession. These marine bands are thin mudstone horizons (up to 30 m) deposited during marine flooding of the delta plain. Some of these marine bands are characterised by a high uranium-enrichment, which is detectable by gamma-ray devices. However, the marine bands found in the Netherlands do not show these enrichments. A relatively high siliciclastic sedimentation rate and the (periodic) absence of anoxic bottom-water conditions are probably the main factors limiting the enrichment of uranium and other trace elements in these marine bands. The NWECB was fragmented into a number of sub-basins during the Late Westphalian due to long-wavelength folding and faulting. Most of the gas reservoirs in Carboniferous rocks are found in thick fluvial sandstones deposited during this time. In the northeastern part of the Netherlands, the Coevorden Gasfield is characterised by 40m-thick fluvial sandstones of Late Westphalian age. In this thesis, a detailed reconstruction is presented of the alluvial architecture of the Coevorden Field