Browsing by Author "Rodrigo A. Gutiérrez"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- ItemArabidopsis thaliana interaction with Ensifer meliloti can support plant growth under N-deficiency(2020) Grace Armijo; Tatiana Kraiser; María P. Medina; Diana E. Gras; Ana Zúñiga; Bernardo González; Rodrigo A. GutiérrezNitrogen (N) is an essential macronutrient for plants. Some plant species obtain this nutrient by interacting with N-fixing bacteria. These beneficial interactions are well described in legumes but have also been observed in non-legume plant species that are unable to form root nodules. We studied the expanding role of beneficial plant-bacteria interactions for N-nutrition in the widely used model plant Arabidopsis thaliana. We found that the bacteria Ensifer meliloti enhanced A. thaliana growth under severe N-deficiency conditions, allowing plants to complete their life cycle. Our results showed that bacteria colonize the rhizosphere associated with the epidermis of the plant root. We also demonstrated that A. thaliana possesses genes that are critical for this beneficial interaction and are required for plant-growth promotion by E. meliloti under N-deficiency. This work shows association between A. thaliana and E. meliloti for plant nutrition under severe N-deficiency, and suggests that plants have conserved-molecular mechanisms to interact with N-fixing bacteria to procure N and escape adverse conditions. Under these circumstances, the supply of N via N-fixation is critical for survival, allowing the plant to complete its life cycle. Our findings provide a new framework and an experimental model system that expand our understanding of plant-rhizobia interactions for plant N-nutrition.
- ItemRevealing hidden plant diversity in arid environments(2021) Gabriela Carrasco‐Puga; Francisca P. Díaz; Daniela C. Soto; Catalina Hernández‐Castro; Orlando Contreras‐López; Antonio Maldonado; Claudio Latorre; Rodrigo A. GutiérrezEstimating total plant diversity in extreme or hyperarid environments can be challenging, as adaptations to pronounced climate variability include evading prolonged stress periods through seeds or specialized underground organs. Short-term surveys of these ecosystems are thus likely poor estimators of actual diversity. Here we develop a multimethod strategy to obtain a more complete understanding of plant diversity from a community in the Atacama Desert. We explicitly test environmental DNA-based techniques (eDNA) to see if they can reveal the observed and ‘hidden' (dormant or locally rare) species. To estimate total plant diversity, we performed long-term traditional surveys during eight consecutive years, including El Niño and La Niña events, we then analyzed eDNA from soil samples using high-throughput sequencing. We further used soil pollen analysis and soil seed bank germination assays to identify ‘hidden' species. Each approach offers different subsets of current biodiversity at different taxonomic, spatial and temporal resolution, with a total of 92 taxa identified along the transect. Traditional field surveys identified 77 plant species over eight consecutive years. Observed community composition greatly varies interannually, with only 22 species seen every year. eDNA analysis revealed 37 taxa, eight of which were ‘hidden' in our field surveys. Soil samples contain a viable seed bank of 21 taxa. Soil pollen (27 taxa) and eDNA analysis show affinities with vegetation at the landscape scale but a weak relationship to local plot diversity. Multimethod approaches (including eDNA) in deserts are valuable tools that add to a comprehensive assessment of biodiversity in such extreme environments, where using a single method or observations over a few years is insufficient. Our results can also explain the resilience of Atacama plant communities as ‘hidden' taxa may have been active in the recent past or could even emerge in the future as accelerated global environmental change continues unabated.
- ItemSignaling pathways involved in the repression of root nitrate uptake by nitrate in Arabidopsis thaliana(2022) Valentin Chaput; Jianfu Li; David Séré; Pascal Tillard; Cécile Fizames; Tomas Moyano; Kaijing Zuo; Antoine Martin; Rodrigo A. Gutiérrez; Alain Gojon; Laurence LejayIn Arabidopsis thaliana, root high-affinity nitrate (NO3-) uptake depends mainly on NRT2.1, 2.4 and 2.5, which are repressed by high NO3- supply at the transcript level. For NRT2.1, this regulation is due to the action of (i) feedback downregulation by N metabolites and (ii) repression by NO3- itself mediated by the transceptor NRT1.1(NPF6.3). However, for NRT2.4 and NRT2.5 the signaling pathway(s) remain unknown along with the molecular elements involved. Here we show that unlike NRT2.1, NRT2.4 and NRT2.5 are not induced in a NO3- reductase mutant but are strongly upregulated following replacement of NO3- by ammonium (NH4+) as the N source. Moreover, increasing NO3- concentration in a mixed nutrient solution with constant NH4+ concentration results in a gradual repression of NRT2.4 and NRT2.5, which is suppressed in a nrt1.1 mutant. This indicates that NRT2.4 and NRT2.5 are subjected to repression by NRT1.1-mediated NO3- sensing, and not to feedback repression by reduced N metabolites. We further show that key regulators of NRT2s transporters, such as HHO1, HRS1, PP2C, LBD39, BT1 and BT2, are also regulated by NRT1.1-mediated NO3- sensing, and that several are involved in NO3- repression of NRT2.1, 2.4 and 2.5. Finally, we provide evidence that it is the phosphorylated form of NRT1.1 at the T101 residue, which is most active in triggering the NRT1.1-mediated NO3- regulation of all these genes. Altogether, these data led to propose a regulatory model for high-affinity NO3- uptake in Arabidopsis, highlighting several NO3- transduction cascades downstream the phosphorylated form of the NRT1.1 transceptor. One sentence summary Characterisation and identification of molecular elements involved in the signaling pathways repressing NRT2s transporters and root nitrate uptake in response to nitrate.