Biology subjects

Manacorda, C. A.

Publications and source records attributed to Manacorda, C. A..

5 recordsLinked to original sources

bioRxiv2025

Root Hydraulic Conductivity and Transpiration in Arabidopsis: Coordination Revealed by a High-Stomatal-Density Mutant

Background and aimsUnderstanding the coordination between root and shoot hydraulics is fundamental for improving plant performance under water stress. In this study, we investigated how shoot traits that enhance transpiration influence root hydraulic properties, using the Arabidopsis thaliana double mutant epf1 epf2, characterized by high stomatal density and increased transpiration. MethodsPlant lines epf1 epf2 and Col-0 (wild type) were grown hydroponically and compared for stomatal traits, rate of water loss, leaf and root water relations, aquaporin expression, and root hydraulic conductivity (Lpr). Then, to assess responses to water deficit, osmotic stress was induced by adding 2% polyethylene glycol (PEG) to the nutrient solution seven days before measurements. Key resultsThe epf1 epf2 double mutant exhibited [~]150% higher stomatal density, yet stomatal conductance and short-term rosette water loss increased by only [~]30% relative to wild type. Despite higher water loss, the mutant maintained its leaf relative water content, concomitant with a more negative leaf osmotic potential; root osmotic potential was similar between genotypes. epf1 epf2 showed lower Lpr than Col-0. Aquaporin transcript levels and the relative aquaporin contribution to root water transport did not differ between genotypes. Under osmotic stress, Col-0 instead showed lower Lpr than epf1 epf2, again without changes in aquaporin expression or relative contribution. ConclusionsOur results highlight an active contribution of the root as a modulator of the whole-plant hydraulic balance. Across scenarios where xylem tension was expected to increase, stomatal aperture and Lpr decreased. We suggest that enhanced transpiration elevates xylem tension, which acts as a long-distance cue, eliciting coordinated reductions in stomatal aperture and Lpr, thereby constraining water flux.

plant biology↗

bioRxiv2025

A viral infection reshapes Arabidopsis water management via root hydraulics, aquaporin downregulation and osmotic adjustment

The effect of plant viruses on root water relations and on how roots and shoots coordinate under infection remains poorly understood. Using a hydroponic Arabidopsis thaliana-Turnip mosaic virus (TuMV) pathosystem, we integrated biometric, anatomical, hydraulic, and gas-exchange measurements to dissect how viral infection reshapes root-shoot water relations. TuMV impaired root development, as reflected by an early plateau of primary root elongation. At the functional level, infected plants exhibited a decrease in root hydraulic conductance per unit root mass, concomitant with transcriptional downregulation of root aquaporin genes. Despite this, the relative contribution of aquaporin-mediated water transport, assessed via sodium azide inhibition, remained unchanged, indicating that the virus downregulates total hydraulic capacity without altering the apoplastic-symplastic partitioning of water flow. Gas-exchange analysis revealed a virus-induced decoupling between stomatal conductance and net CO2 assimilation, resulting in a non-adaptive increase in intrinsic water-use efficiency. This loss of photosynthetic plasticity, combined with shoot-localized osmotic adjustment (more negative leaf osmotic potential and higher relative water content), points to a constrained, suboptimal physiological state. Multivariate analysis confirmed that variation in physiological traits largely drives phenotypic divergence between treatments. Together, these coordinated alterations, reduced root hydraulics, rigid gas-exchange relationships and passive hydraulic matching to a stunted shoot, depict plants locked into a low-performance equilibrium, poorly equipped to compete for water and carbon. This work reveals a systemic hydraulic-photosynthetic reconfiguration that could account for compromises in plant resilience and resource competitiveness. HighlightTuMV infection induces a coordinated whole-plant hydraulic reconfiguration characterized by premature growth arrest, reduced root hydraulic conductance, and decoupling of stomatal conductance from photosynthesis, resulting in a constrained physiological state.

plant biology↗

bioRxiv2021

TuMV infection alters miR168/AGO1 and miR403/AGO2 systems regulation in Arabidopsis

Plant Argonaute proteins, chiefly AGO1 and 2, restrict viral infections. AGO1/2 also participate in developmental processes and are tightly regulated by microRNAs. Under viral infections, the regulatory loop comprising miR168/AGO1 is well studied, but much less so the miR403/AGO2 system. We studied both regulatory systems in TuMV-infected Arabidopsis plants. TuMV downregulated miRNAs precursor molecules, but mature miRNAs overaccumulated, without evidence of transcriptional alteration. AGO1 protein remained at basal levels whereas AGO2 overaccumulated. These results are in line with previous reports studying abiotic and biotic impact on microRNA biogenesis and AGO-dependent antiviral defense, expanding our knowledge of the miR403/AGO2 regulatory system.

plant biology↗

bioRxiv2020

TuMV triggers stomatal closure but reduces drought tolerance in Arabidopsis

i)In this work the effects of TuMV infection on stomatal closure and water balance were studied in Arabidopsis. Thermal imaging analyses showed that TuMV-infected plants had consistently higher foliar temperature than mock treated controls. Non-destructive time-course experiments revealed that this differential phenotype was stable during both daytime and nighttime. This effect was due to reduced gas exchange in TuMV-infected plants, as observed through stomatal conductance and stomatal aperture assays in systemic leaves. Measurements of daily water consumption and initial dehydration rate further proved that TuMV infection reduced water loss. Salicylic acid (SA) and abscisic acid (ABA) contents were increased in TuMV-infected plants. In addition, the expression of ABI2, involved in ABA signaling, was enhanced, and ABCG40 (required for ABA transport into guard cells) was highly induced upon TuMV infection. Hypermorfic abi2-1 mutant plants, but no other ABA or SA biosynthetic, signaling or degradation mutants tested abolished both stomatal closure and low stomatal conductance phenotypes caused by TuMV. Therefore, not overall ABA levels, but localized differences in ABA import and perception in guard cells, are likely to be responsible for stomatal closure observed under TuMV infection. Plants simultaneously subjected to drought and viral stresses showed higher mortality rates than their mock-inoculated drought stressed counterparts, consistent with down-regulation of drought-responsive gene RD29A, both in short and long day conditions. Our findings indicate that in spite of stomatal closure triggered by TuMV, additional phenomena cause compromised drought tolerance of TuMV-infected Arabidopsis plants. ii) Significance statementCharacterization of the physiological responses controlling plant water management under combined stresses and the genes behind them is important in the current climate change scenario, which poses multifaceted challenges to crops. We found that TuMV infection induced ABA and SA accumulation and stomatal closure in Arabidopsis, alongside with overexpression of ABCG40 (the transporter of ABA to guard cells), whereas the dehydration-responsive gene RD29A was downregulated, concomitantly with increased plant susceptibility to drought stress under infection.

molecular biology↗

bioRxiv2017

Arabidopsis phenotyping through Geometric Morphometrics

In recent years, much technical progress has been done regarding plant phenotyping including the model species Arabidopsis thaliana. With automated, high-throughput platforms and the development of improved algorithms for the rosette segmentation task, it is now possible to massively extract reliable shape and size parameters for genetic, physiological and environmental studies. The development of low-cost phenotyping platforms and freeware resources make it possible to widely expand phenotypic analysis tools for Arabidopsis. However, objective descriptors of shape parameters that could be used independently of platform and segmentation software used are still lacking and shape descriptions still rely on ad hoc or even sometimes contradictory descriptors, which could make comparisons difficult and perhaps inaccurate. Modern geometric morphometrics is a family of methods in quantitative biology proposed to be the main source of data and analytical tools in the emerging field of phenomics studies. It has been used for taxonomists and paleontologists for decades and is now a mature discipline. By combining geometry, multivariate analysis and powerful statistical techniques, it offers the possibility to reproducibly and accurately account for shape variations amongst groups. Based on the location of homologous landmarks points over photographed or scanned specimens, these tools could identify the existence and degree of shape variation and measure them in standard units. Here, it is proposed a particular scheme of landmarks placement on Arabidopsis rosette images to study shape variation in the case study of viral infection processes. Several freeware-based geometric morphometric tools are applied in order to exemplify the usefulness of this approach to the study of phenotypes in this model plant. These methods are concisely presented and explained. Shape differences between controls and infected plants are quantified throughout the infectious process and visualized with the appealing graphs that are a hallmark of these techniques and render complex mathematical analysis simple outcomes to interpret. Quantitative comparisons between two unrelated ssRNA+ viruses are shown and reproducibility issues are assessed. Combined with the newest automatons and plant segmentation procedures, geometric morphometric tools could boost phenotypic features extraction and processing in an objective, reproducible manner.

plant biology↗