Arabidopsis ABCG34 contributes to defense against necrotrophic pathogens by mediating the secretion of camalexin

Plant pathogens cause huge yield losses. Plant defense often depends on toxic secondary metabolites that inhibit pathogen growth. Because most secondary metabolites are also toxic to the plant, specific transporters are needed to deliver them to the pathogens. To identify the transporters that function in plant defense, we screened Arabidopsis thaliana mutants of full-size ABCG transporters for hypersensitivity to sclareol, an antifungal compound. We found that atabcg34 mutants were hypersensitive to sclareol and to the necrotrophic fungi Alternaria brassicicola and Botrytis cinerea. AtABCG34 expression was induced by A. brassicicola inoculation as well as by methyl-jasmonate, a defense-related phytohormone, and AtABCG34 was polarly localized at the external face of the plasma membrane of epidermal cells of leaves and roots. atabcg34 mutants secreted less camalexin, a major phytoalexin in A. thaliana, whereas plants overexpressing AtABCG34 secreted more camalexin to the leaf surface and were more resistant to the pathogen. When treated with exogenous camalexin, atabcg34 mutants exhibited hypersensitivity, whereas BY2 cells expressing AtABCG34 exhibited improved resistance. Analyses of natural Arabidopsis accessions revealed that AtABCG34 contributes to the disease resistance in naturally occurring genetic variants, albeit to a small extent. Together, our data suggest that AtABCG34 mediates camalexin secretion to the leaf surface and thereby prevents A. brassicicola infection.117Ysciescopu

Density and P‐wave velocity structure beneath the Paraná Magmatic Province: Refertilization of an ancient lithospheric mantle

We estimate density and P‐wave velocity perturbations in the mantle beneath the southeastern South America plate from geoid anomalies and P‐wave traveltime residuals to constrain the structure of the lithosphere underneath the Paraná Magmatic Province (PMP) and conterminous geological provinces. Our analysis shows a consistent correlation between density and velocity anomalies. The P‐wave speed and density are 1% and 15 kg/m3 lower, respectively, in the upper mantle under the Late Cretaceous to Cenozoic alkaline provinces, except beneath the Goiás Alkaline Province (GAP), where density (+20 kg/m3) and velocity (+0.5%) are relatively high. Underneath the PMP, the density is higher by about 50 kg/m3 in the north and 25 kg/m3 in the south, to a depth of 250 − 300 km. These values correlate with high‐velocity perturbations of +0.5% and +0.3%, respectively. Profiles of density perturbation versus depth in the upper mantle are different for the PMP and the adjacent Archean São Francisco (SFC) and Amazonian (AC) cratons. The Paleoproterozoic PMP basement has a high‐density root. The density is relatively low in the SFC and AC lithospheres. A reduction of density is a typical characteristic of chemically depleted Archean cratons. A more fertile Proterozoic and Phanerozoic subcontinental lithospheric mantle has a higher density, as deduced from density estimates of mantle xenoliths of different ages and composition. In conjunction with Re‐Os isotopic studies of the PMP basalts, chemical and isotopic analyses of peridodite xenoliths from the GAP in the northern PMP, and electromagnetic induction experiments of the PMP lithosphere, our density and P‐wave speed models suggest that the densification of the PMP lithosphere and flood basalt generation are related to mantle refertilization. Metasomatic refertilization resulted from the introduction of asthenospheric components from the mantle wedge above Proterozoic subduction zones, which surrounded the Paraná lithosphere. The high‐density PMP lithosphere is presently gravitationally unstable and prone to delamination.Key Points:Density and P‐wave velocity in the lithospheric mantle beneath the Paraná Magmatic Province are highHigh density precludes a depleted cratonic lithosphere and indicates refertilized lithospheric mantleBasalt magmatism suggests refertilized mantle with asthenospheric components from mantle wedgePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134193/1/ggge21079-sup-0003-2016GC006369-fs02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134193/2/ggge21079-sup-0004-2016GC006369-fs03.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134193/3/ggge21079-sup-0002-2016GC006369-fs01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134193/4/ggge21079_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134193/5/ggge21079.pd

Geo-neutrinos: A systematic approach to uncertainties and correlations

Geo-neutrinos emitted by heat-producing elements (U, Th and K) represent a unique probe of the Earth interior. The characterization of their fluxes is subject, however, to rather large and highly correlated uncertainties. The geochemical covariance of the U, Th and K abundances in various Earth reservoirs induces positive correlations among the associated geo-neutrino fluxes, and between these and the radiogenic heat. Mass-balance constraints in the Bulk Silicate Earth (BSE) tend instead to anti-correlate the radiogenic element abundances in complementary reservoirs. Experimental geo-neutrino observables may be further (anti)correlated by instrumental effects. In this context, we propose a systematic approach to covariance matrices, based on the fact that all the relevant geo-neutrino observables and constraints can be expressed as linear functions of the U, Th and K abundances in the Earth's reservoirs (with relatively well-known coefficients). We briefly discuss here the construction of a tentative "geo-neutrino source model" (GNSM) for the U, Th, and K abundances in the main Earth reservoirs, based on selected geophysical and geochemical data and models (when available), on plausible hypotheses (when possible), and admittedly on arbitrary assumptions (when unavoidable). We use then the GNSM to make predictions about several experiments ("forward approach"), and to show how future data can constrain - a posteriori - the error matrix of the model itself ("backward approach"). The method may provide a useful statistical framework for evaluating the impact and the global consistency of prospective geo-neutrino measurements and Earth models.Comment: 17 pages, including 4 figures. To appear on "Earth, Moon, and Planets," Special Issue on "Neutrino Geophysics," Proceedings of Neutrino Science 2005 (Honolulu, Hawaii, Dec. 2005

Heterogeneous coupling of the Sumatran megathrust constrained by geodetic and paleogeodetic measurements

Geodetic and paleogeodetic measurements of interseismic strain above the Sumatran portion of the Sunda subduction zone reveal a heterogeneous pattern of coupling. Annual banding in corals provides vertical rates of deformation spanning the last half of the 20th century, and repeated GPS surveys between 1991 and 2001 and continuous measurements at GPS stations operated since 2002 provide horizontal velocities. Near the equator, the megathrust is locked over a narrow width of only a few tens of kilometers. In contrast, the locked fault zone is up to about 175 km wide in areas where great interplate earthquakes have occurred in the past. Formal inversion of the data reveals that these strongly coupled patches are roughly coincident with asperities that ruptured during these events. The correlation is most spectacular for rupture of the M_w 8.7 Nias-Simeulue earthquake of 2005, which released half of the moment deficit that had accumulated since its previous rupture in 1861, suggesting that this earthquake was overdue. Beneath the Mentawai islands, strong coupling is observed within the overlapping rupture areas of the great earthquakes of 1797 and 1833. The accumulated slip deficit since these events is slowly reaching the amount of slip that occurred during the 1833 earthquake but already exceeds the slip that occurred during the 1797 earthquake. Thus, rerupture of part of the Mentawai patch in September 2007 was not a surprise. In contrast, coupling is low below the Batu islands near the equator and around Enggano island at about 5°S, where only moderate earthquakes (M_w < 8.0) have occurred in the past two centuries. The correlation of large seismic asperities with patches that are locked during the interseismic period suggests that they are persistent features. This interpretation is reinforced by the fact that the large locked patches and great ruptures occur beneath persistent geomorphologic features, the largest outer arc islands. Depth- and convergence-rate-dependent temperature might influence the pattern of coupling, through its effect on the rheology of the plate interface, but other influences are required to account for the observed along-strike heterogeneity of coupling. In particular, subduction of the Investigator Fracture Zone could be the cause for the low coupling near the equator

Unravelling the reasons for disproportion in the ratio of AOB and NOB in aerobic granular sludge

In this study, we analysed the nitrifying microbial community (ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB)) within three different aerobic granular sludge treatment systems as well as within one flocculent sludge system. Granular samples were taken from one pilot plant run on municipal wastewater as well as from two lab-scale reactors. Fluorescent in situ hybridization (FISH) and quantitative PCR (qPCR) showed that Nitrobacter was the dominant NOB in acetate-fed aerobic granules. In the conventional system, both Nitrospira and Nitrobacter were present in similar amounts. Remarkably, the NOB/AOB ratio in aerobic granular sludge was elevated but not in the conventional treatment plant suggesting that the growth of Nitrobacter within aerobic granular sludge, in particular, was partly uncoupled from the lithotrophic nitrite supply from AOB. This was supported by activity measurements which showed an approximately threefold higher nitrite oxidizing capacity than ammonium oxidizing capacity. Based on these findings, two hypotheses were considered: either Nitrobacter grew mixotrophically by acetate-dependent dissimilatory nitrate reduction (ping-pong effect) or a nitrite oxidation/nitrate reduction loop (nitrite loop) occurred in which denitrifiers reduced nitrate to nitrite supplying additional nitrite for the NOB apart from the AOB

Significant release of shear energy of the North Korean nuclear test on February 12, 2013

On February 12, 2013 the Democratic People\u27s Republic of Korea (DPRK) carried out an announced nuclear test, which was the third after tests conducted in 2006 and 2009. An important task in discriminating a man-made explosion and a natural tectonic earthquake is the analysis of seismic waveforms. To determine the isotropic and non-isotropic characteristics of the detonation source, I invert long-period seismic data for the full seismic moment tensor to match the observed seismic signals by synthetic waveforms based on a 3D earth model. Here, I show that the inversion of long-period seismic data of the 2013 test reveals a clear explosive (isotropic) component combined with a significant release of shear energy by the double-couple part of the moment tensor. While the isotropic part of the nuclear test in 2009 was similar to that in 2013, the double-couple part was lower by a factor of 0.55 compared to the explosion in 2013. Moreover, the ratio of the isotropic seismic moments of the 2013 and 2009 nuclear tests is 1.4±0.1 and lower than published estimations of the yield ratio, which indicates the importance of considering the release of shear energy. The determined orientation of the double-couple fault plane is parallel to the dominating geologic fault structures NNE-SSW to NE-SW, but the calculated normal faulting mechanism does not correspond to the general tectonic strike-slip regime. Thus, explanations for the enhanced release of shear energy might be induced dip-slip motion pre-stressed by the previous test or near source damaging effects due to a changed containment of the nuclear explosion