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Drought represents a major threat to food security. Mechanistic data describing plant responses to drought have been studied extensively and genes conferring drought resistance have been introduced into crop plants. However, plants with enhanced drought resistance usually display lower growth, highlighting the need for strategies to uncouple drought resistance from growth. Here, we show that overexpression of BRL3, a vascular-enriched member of the brassinosteroid receptor family, can confer drought stress tolerance in Arabidopsis . Whereas loss-of-function mutations in the ubiquitously expressed BRI1 receptor leads to drought resistance at the expense of growth, overexpression of BRL3 receptor confers drought tolerance without penalizing overall growth. Systematic analyses reveal that upon drought stress, increased BRL3 triggers the accumulation of osmoprotectant metabolites including proline and sugars. Transcriptomic analysis suggests that this results from differential expression of genes in the vascular tissues. Altogether, this data suggests that manipulating BRL3 expression could be used to engineer drought tolerant crops. Drought resistant plants typically have reduced growth. Here the authors show that overexpression of the BRL3 brassinosteroid receptor confers drought tolerance and accumulation of osmoprotectant metabolites without penalizing growth, demonstrating that drought response and growth can be uncoupled.

Environmental drought and high salinity impose osmotic stress, which inhibits plant growth and yield. Thus, understanding how plants respond to osmotic stress is critical to improve crop productivity. Plants have multiple signalling pathways in response to osmotic stress in which the phytohormone abscisic acid (ABA) plays important roles. However, since little is known concerning key early components, the global osmotic stress-signalling network remains to be elucidated. Here, we review recent advances in the identification of osmotic-stress activated Raf-like protein kinases as regulators of ABA-dependent and -independent signalling pathways and discuss the plant stress-responsive kinase network from an evolutionary perspective. A better understanding of how plants respond to osmotic stress could potentially help improve crop yields. Here Fàbregas et al. review the recent characterization of Raf-like kinases that act in both in ABA-dependent and -independent responses to osmotic stress.

Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants.

Metabolic regulation is one of the main mechanisms involved in the maintenance of cell osmotic potential under abiotic stress. To date, metabolite profiling approaches have been extensively used to characterize the molecular responses to abiotic stress in many plant species. However, studies revealing the specific metabolic responses of plants exposed to water-deficit stress remain limited. Here, we review the most recent developments that advance our understanding of the metabolic response to drought stress in Arabidopsis and rice. We provide an updated schematic overview of the specific metabolic signature of wild-type plants in response to drought.

Brassinosteroid (BR) hormones are primarily perceived at the cell surface by the leucine-rich repeat receptor-like kinase BRASSINOSTEROID INSENSITIVE1 (BRI1). In Arabidopsis thaliana, BRI1 has two close homologs, BRI1-LIKE1 (BRL1) and BRL3, respectively, which are expressed in the vascular tissues and regulate shoot vascular development. Here, we identify novel components of the BRL3 receptor complex in planta by immunoprecipitation and mass spectrometry analysis. Whereas BRI1 ASSOCIATED KINASE1 (BAK1) and several other known BRI1 interactors coimmunoprecipitated with BRL3, no evidence was found of a direct interaction between BRI1 and BRL3. In addition, we confirmed that BAK1 interacts with the BRL1 receptor by coimmunoprecipitation and fluorescence microscopy analysis. Importantly, genetic analysis of brl1 brl3 bak1-3 triple mutants revealed that BAK1, BRL1, and BRL3 signaling modulate root growth and development by contributing to the cellular activities of provascular and quiescent center cells. This provides functional relevance to the observed protein—protein interactions of the BRL3 signalosome. Overall, our study demonstrates that cell-specific BR receptor complexes can be assembled to perform different cellular activities during plant root growth, while highlighting that immunoprecipitation of leucine-rich repeat receptor kinases in plants is a powerful approach for unveiling signaling mechanisms with cellular resolution in plant development.

Drought is a major cause of agricultural losses worldwide. Climate change will intensify drought episodes threatening agricultural sustainability. Gaining insights into drought response mechanisms is vital for crop adaptation to climate emergency. To date, only few studies report comprehensive analyses of plant metabolic adaptation to drought. Here, we present a multifactorial metabolomic study of early-mid drought stages in the model plant Arabidopsis thaliana. We sampled root and shoot tissues of plants subjected to water withholding over a six-day time course, including brassinosteroids receptor mutants previously reported to show drought tolerance phenotypes. Furthermore, we sequenced the root transcriptome at basal and after 5 days drought, allowing direct correlation between metabolic and transcriptomic changes and the multi-omics integration. Significant abiotic stress signatures were already activated at basal conditions in a vascular-specific receptor overexpression (BRL3ox). These were also rapidly mobilized under drought, revealing a systemic adaptation strategy driven from inner tissues of the plant. Overall, this dataset provides a significant asset to study drought metabolic adaptation and allows its analysis from multiple perspectives.Measurement(s)gene expression • metaboliteTechnology Type(s)gene expression detection method • gas chromatography time-of-flight mass spectrometryFactor Type(s)time • drought • genotype • plant tissueSample Characteristic - OrganismArabidopsis thalianaSample Characteristic - Environmentgreenhouse soilMachine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.17705021

Background Long-read sequencing in metagenomics facilitates the assembly of complete genomes out of complex microbial communities. These genomes include essential biologic information such as the ribosomal genes or the mobile genetic elements, which are usually missed with short-reads. We applied long-read metagenomics with Nanopore sequencing to retrieve high-quality metagenome-assembled genomes (HQ MAGs) from a dog fecal sample. Results We used nanopore long-read metagenomics and frameshift aware correction on a canine fecal sample and retrieved eight single-contig HQ MAGs, which were > 90% complete with < 5% contamination, and contained most ribosomal genes and tRNAs. At the technical level, we demonstrated that a high-molecular-weight DNA extraction improved the metagenomics assembly contiguity, the recovery of the rRNA operons, and the retrieval of longer and circular contigs that are potential HQ MAGs. These HQ MAGs corresponded to Succinivibrio , Sutterella , Prevotellamassilia , Phascolarctobacterium , Catenibacterium, Blautia , and Enterococcus genera. Linking our results to previous gastrointestinal microbiome reports (metagenome or 16S rRNA-based), we found that some bacterial species on the gastrointestinal tract seem to be more canid-specific – Succinivibrio , Prevotellamassilia , Phascolarctobacterium , Blautia _A sp900541345 –, whereas others are more broadly distributed among animal and human microbiomes – Sutterella , Catenibacterium , Enterococcus, and Blautia sp003287895 . Sutterella HQ MAG is potentially the first reported genome assembly for Sutterella stercoricanis , as assigned by 16S rRNA gene similarity. Moreover, we show that long reads are essential to detect mobilome functions, usually missed in short-read MAGs. Conclusions We recovered eight single-contig HQ MAGs from canine feces of a healthy dog with nanopore long-reads. We also retrieved relevant biological insights from these specific bacterial species previously missed in public databases, such as complete ribosomal operons and mobilome functions. The high-molecular-weight DNA extraction improved the assembly’s contiguity, whereas the high-accuracy basecalling, the raw read error correction, the assembly polishing, and the frameshift correction reduced the insertion and deletion errors. Both experimental and analytical steps ensured the retrieval of complete bacterial genomes.

The plant vascular system provides transport and support capabilities that are essential for plant growth and development, yet the mechanisms directing the arrangement of vascular bundles within the shoot inflorescence stem remain unknown. We used computational and experimental biology to evaluate the role of auxin and brassinosteroid hormones in vascular patterning in ARABIDOPSIS: We show that periodic auxin maxima controlled by polar transport and not overall auxin levels underlie vascular bundle spacing, whereas brassinosteroids modulate bundle number by promoting early procambial divisions. Overall, this study demonstrates that auxin polar transport coupled to brassinosteroid signaling is required to determine the radial pattern of vascular bundles in shoots.

Staphylococcus pseudintermedius, a common commensal canine bacterium, is the main cause of skin infections in dogs and is a potential zoonotic pathogen. The emergence of methicillin-resistant S. pseudintermedius (MRSP) has compromised the treatment of infections caused by these bacteria. In this study, we compared the phenotypic results obtained by minimum inhibitory concentration (MICs) for 67 S. pseudintermedius isolates from the skin of nine healthy dogs versus the genotypic data obtained with Nanopore sequencing. A total of 17 antibiotic resistance genes (ARGs) were detected among the isolates. A good correlation between phenotype and genotype was observed for some antimicrobial classes, such as ciprofloxacin (fluoroquinolone), macrolides, or tetracycline. However, for oxacillin (beta-lactam) or aminoglycosides the correlation was low. Two antibiotic resistance genes were located on plasmids integrated in the chromosome, and a third one was in a circular plasmid. To our knowledge, this is the first study assessing the correlation between phenotype and genotype regarding antimicrobial resistance of S. pseudintermedius from healthy dogs using Nanopore sequencing technology.

Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants.