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Navarro, L.

Publications and source records attributed to Navarro, L..

3 recordsLinked to original sources

The geography of the Anthropocene differs between the land and the sea

O_LIClimate change and other anthropogenic drivers of biodiversity change are unequally distributed across the world. The geographic patterns of different drivers, and the spatial overlap among these drivers, have important implications for the direction and pace of biodiversity change, yet are not well documented. Moreover, it is unknown if the geographic patterns of drivers differ between the terrestrial and marine realm, as expected due to marked differences in how humans interact with the land and ocean. C_LIO_LIWe compiled global gridded datasets on climate change, land-use, resource exploitation, pollution, species invasions, and human population density. We used multivariate statistics to examine the spatial relationships among the datasets and to characterize the typical combinations of drivers experienced by different parts of the world. C_LIO_LIWe found stronger positive correlations among drivers in the terrestrial than in the marine realm, leading to areas of high intensities of multiple drivers on land. Climate change tended to be negatively correlated with other drivers in the terrestrial realm (e.g., in the tundra and boreal forest with high climate change but low human use and pollution) whereas the opposite was true in the marine realm (e.g., in the Indo-Pacific with high climate change and high fishing). C_LIO_LIWe show that different regions of the world can be defined by anthropogenic threat complexes (ATCs), distinguished by different sets of drivers with varying intensities. The ATCs can be used to test hypothesis about the pattern of biodiversity change, especially the joint effects of multiple drivers. More generally, our global analysis highlights the broad conservation priorities needed to mitigate the effects of anthropogenic change on biodiversity responses, with different priorities emerging on land and in the ocean, and in different parts of the world. C_LI

ecology

A bacterial GW-effector targets Arabidopsis AGO1 to promote pathogenicity and induces Effector-triggered immunity by disrupting AGO1 homeostasis

Pseudomonas syringae type III effectors were previously shown to suppress the Arabidopsis microRNA (miRNA) pathway through unknown mechanisms. Here, we first show that the HopT1-1 effector promotes bacterial growth by suppressing the Arabidopsis Argonaute 1 (AGO1)-dependent miRNA pathway. We further demonstrate that HopT1-1 interacts with Arabidopsis AGO1 through conserved glycine/tryptophan (GW) motifs, and in turn suppresses miRNA function. This process is not associated with a general decrease in miRNA accumulation. Instead, HopT1-1 reduces the level of AGO1-associated miRNAs in a GW-dependent manner. Therefore, HopT1-1 alters AGO1-miRISC activity, rather than miRNA biogenesis or stability. In addition, we show that the AGO1-binding platform of HopT1-1 is essential to suppress the production of reactive oxygen species (ROS) and of callose deposits during Pattern-triggered immunity (PTI). These data imply that the RNA silencing suppression activity of HopT1-1 is intimately coupled with its virulence function. Overall, these findings provide sound evidence that a bacterial effector has evolved to directly target a plant AGO protein to suppress PTI and cause disease.

plant biology

Transcriptional control and exploitation of an immune-responsive family of retrotransposons in Arabidopsis

Mobilization of transposable elements (TEs) in plants has been recognized as a driving force of evolution and adaptation, in particular by providing genes with regulatory modules that impact their transcription. In this study, we employed an ATCOPIA93 Long terminal repeats (LTR) promoter-GUS fusion to show that this retrotransposon behaves like an immune-responsive gene during plant defense in Arabidopsis. We also showed that the reactivation of the endogenous ATCOPIA93 copy \"EVD\", in the presence of bacterial stress, is not only negatively regulated by DNA methylation but also by Polycomb-mediated silencing--a mode of repression typically found at protein-coding and microRNA genes. Interestingly, one of the ATCOPIA93-derived soloLTRs is located upstream of the disease resistance gene RPP4 and is devoid of either DNA methylation or H3K27m3 marks. Through loss-of-function experiments, we demonstrated that this soloLTR is required for proper expression of RPP4 during plant defense, thus linking the responsiveness of ATCOPIA93 to biotic stress and the co-option of its LTR for plant immunity.

plant biology