1,720,989 research outputs found
Systemic signalling in legume nodulation: nodule formation and its regulation
No full textLegume plants are able to enter into a symbiotic relationship with rhizobia bacteria. This results in the formation of a novel organ on the root called the nodule, where the rhizobia are housed. The rhizobia provide the host plant with nitrogen in exchange for carbohydrates. Successful nodule formation and sustainable nodulation involve complex signalling events. This includes systemic signalling between the symbiotic partners, and also signalling between the root and shoot of the plant. Factors such as plant hormone levels and environmental conditions for growth influence these systemic signalling pathways. This chapter investigates the different types of long-distance signalling events that are necessary for the development and regulation of legume nodulation
Baluska Frantisek
No full texthttps://www.wellbeingintlstudiesrepository.org/animsent_gallery/1607/thumbnail.jp
Baluska Frantisek
No full texthttps://www.wellbeingintlstudiesrepository.org/animsent_gallery/1607/thumbnail.jp
Exploring Suberin's Functionality in Roots, Shoots and Tubers : A Comparative Analysis
Get PDFSuberization is a key plant process that forms hydrophobic barriers to regulate water loss and substance exchange. This thesis reviews the evolution of our understanding of suberin and related polymers like cutin and lignin, emphasizing their roles in maintaining water balance. A comparative study across five plant species revealed that waxes, rather than suberin quantity or layer number, play a dominant role in reducing transpiration. Investigations in barley roots under drought showed earlier suberin and lignin deposition near the root tip, particularly in wild accessions, along with upregulation of related biosynthetic genes. Soil-grown plants exhibited stronger drought responses than hydroponically grown ones, underlining the importance of natural growth conditions. These findings offer valuable insights for enhancing crop resilience and drought adaptation.Suberinisierung ist ein zentraler Prozess in Pflanzen, bei dem hydrophobe Barrieren gebildet werden, um Wasserverlust zu regulieren und den Stoffaustausch mit der Umwelt zu steuern. Diese Arbeit gibt einen Überblick über die Entwicklung des Verständnisses von Suberin und verwandten Polymeren wie Cutin und Lignin sowie deren Bedeutung für die Aufrechterhaltung des Wasserhaushalts. Eine vergleichende Studie an fünf Pflanzenarten zeigte, dass Wachsablagerungen – und nicht die Menge oder Anzahl suberisierter Zellschichten – entscheidend für die Reduktion der Transpiration sind. Untersuchungen an Gerstenwurzeln unter Trockenstress zeigten eine frühere Ablagerung von Suberin und Lignin nahe der Wurzelspitze, insbesondere bei Wildformen, begleitet von einer erhöhten Expression entsprechender Biosynthesegene. Pflanzen, die in Boden gewachsen waren, zeigten stärkere Stressreaktionen als hydroponisch kultivierte, was die Bedeutung naturnaher Bedingungen unterstreicht. Die Ergebnisse liefern wichtige Erkenntnisse für die Verbesserung der Trockenresistenz und Lagerfähigkeit von Kulturpflanzen
Effect of salt stress on apoplastic barriers in roots and leaves of two barley species
Get PDFIn this study, the responses of 12 d old cultivated barley (Hordeum vulgare L. spp.vulgare) cv Scarlett and a wild accession (Hordeum vulgare spp. sponataneum) from Pakistan (ICB181243) to salt stress of concentrations 80 mM, 180 mM and 275 mM corresponding to water potential equivalents of -0.4 MPa, -0.8 MPa and -1.2 MPa were investigated and compared. The shoot and root responses at morphological, histochemical, biochemical, molecular and physiological levels in terms of stress adaptability and tolerance were studied. The salt stress significantly reduced the growth in both species and was prominent in Pakistan wild barley. Strong apoplastic suberin was formed in both the barley species and also a differential pattern in the degree of suberization was observed between the two genotypes. Further transcriptomic studies in 180 mM stressed roots revealed positive regulation of suberin related genes; and differential regulation of aquaporins and salt stress related genes in both species. Mineral nutrient analysis showed significantly elevated Na accumulation and decreased Ca and K ion levels in both shoots and roots in both genotypes. As a consequence of increased Na levels osmotic adjustment through proline occurred in both barley genotypes. Significant increase in proline levels, especially at higher salt stress concentrations of 180 mM and 275 mM was observed in the leaves and roots of both Scarlett and Pakistan wildtype. The osmotic potential within the roots reduced significantly than the control. The fold decrease in the stressed roots did not vary much between the genotypes. The results from physiological studies also conform to the salinity induced effect through reduced stomatal conductance and photosynthetic yield in the leaves. The wax and cutin amounts varied specifically in leaf 2 due to its detrimental development in salinity. Thus, these results, especially between the cultivar Scarlett and the wild barley from Pakistan show the important role of apoplastic barriers as response to salt stress. The results indicate that wild barley of Pakistan accessions responds more strongly than the cultivar Scarlett in the event of salt stress of different intensities. Further investigations with more wild barley genotypes will improve our understanding of salt stress response and tolerance processes and can be used in future breeding programs to gain more salt tolerant crops
Rapid endocytosis is triggered upon imbibition in Arabidopsis seeds
Get PDFDuring seed imbibition and embryo activation, rapid change from a metabolically resting state to the activation of diverse extracellular and/or membrane bound molecules is essential and, hence, endocytosis could be activated too. In fact, we have documented endocytic internalization of the membrane impermeable endocytic tracer FM4-64 already upon 30 min of imbibition of Arabidopsis seeds. This finding suggest that endocytosis is activated early during seed imbibition in Arabidopsis. Immunolocalization of rhamnogalacturonan-II (RG-II) complexed with boron showed that whereas this pectin is localized only in the cell walls of dry seed embryos, it starts to be intracellular once the imbibition started. Brefeldin A (BFA) exposure resulted in recruitment of the intracellular RG-II pectin complexes into the endocytic BFA-induced compartments, confirming the endocytic origin of the RG-II signal detected intracellularly. Finally, germination was significantly delayed when Arabidopsis seeds were germinated in the presence of inhibitors of endocytic pathways, suggesting that trafficking of extracellular molecules might play an important role in the overcome of germination. This work constitutes the first demonstration of endocytic processes during germination and opens new perspectives about the role of the extracellular matrix and membrane components in seed germination.Fil: Pagnussat, Luciana Anabella. Universidad Nacional de Mar del Plata; ArgentinaFil: Burbach, Christian. University of Bonn; AlemaniaFil: Baluska, Frantisek. University of Bonn; AlemaniaFil: de la Canal, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentin
Aluminum Stress on Suberin Biosynthesis in Barley (Hordeum vulgare) Roots
Get PDFAluminum (Al) toxicity is a major factor inhibiting plant growth in acidic soils worldwide, and the root barrier formed by suberized cells is an important mechanism for plants to resist environmental stress. The aim of this study was to investigate the effect of Al stress on the synthesis of suberin in barley (Hordeum vulgare) roots and the role of suberin in resisting Al stress.
This study investigated the effect of different pH conditions on root development and suberin biosynthesis in barley seedlings, with a particular focus on the impact of Al stress and silicon supplementation. The results indicated that the length and dry weight of seminal roots in barley were not significantly affected by pH, but Al stress led to a noticeable reduction in root growth. However, the addition of Si to the solution medium containing 50 µM Al mitigated the adverse effects of Al stress on root growth. The results also showed that 4 days of Al stress could significantly increase the distribution and content of suberin in barley roots through FY staining observation and GC chemical analysis. The analysis of the aliphatic suberin monomer composition in various zones of barley roots grown under distinct pH conditions also showed no significant differences. However, the amount of suberin increased under Al stress, with Si supplementation leading to a reduction in suberin deposition. Analysis of RNA-seq data and qPCR analysis showed that Al stress could induce the expression of a series of genes related to suberin synthesis, among which the key gene for suberin synthesis, CYP86B1, was crucial in the Al stress response. Under Al stress, Al-induced suberization in the barley cyp86b1 mutants was significantly lower than in wild-type barley. In parallel, a series of ABA-related genes involved in ABA biosynthesis, degradation, and signalling were upregulated under Al stress, indicating that Al treatment could induce ABA synthesis and possibly regulate Al-induced suberization by modulating the ABA pathway. Furthermore, in the presence of the ABA synthesis inhibitor fluridone, Al stress could no longer induce changes in suberin. Morin staining showed that the presence or absence of suberin lamellae had a significant effect on the transport of Al in roots. In the absence of suberin, more Al entered the xylem of the root. However, after 4 days of Al treatment, the presence or absence of suberin did not affect the growth status of the barley aboveground part
Molecular insights into abiotic stress responses in barley and Arabidopsis
Get PDFThis cumulative thesis, titled "Molecular insights into abiotic stress responses in barley and Arabidopsis", investigates two critical aspects of plant responses to abiotic stress. The first part explores hydrogen peroxide (H2O2) and its interaction with calcium (Ca2+) signalling in barley (Hordeum vulgare L.), while the second part examines drought stress regulation in Arabidopsis thaliana, revealing a novel mechanism involving the genes GASA3 and AFP1.
H2O2 plays a pivotal role in signalling pathways that enable plants to adapt to environmental challenges. Despite its importance, its transcriptomic impact remains underexplored. To address this, RNA-Seq analysis was used to examine changes in gene expression in barley roots and leaves after H2O2 treatment. This revealed 1883 differentially expressed genes (DEGs) in roots and 1001 in leaves, with most responses being tissue-specific. Only 209 DEGs were commonly regulated, and 37 showed opposing regulation across tissues. Gene ontology (GO) analysis highlighted the organ-specific nature of the response: leaf DEGs were enriched in hormone signalling, H2O2 response, and abiotic stress adaptation, while root DEGs were associated with H2O2 detoxification, glutathione metabolism, and cell wall modifications. A follow-up study examined the cross-talk between H2O2 and Ca2+ signalling using RNA-Seq under conditions that blocked Ca2+-transients. By comparing expression profiles from H2O2-only and LaCl3+H2O2 treatments, 331 Ca2+-dependent H2O2-responsive genes in leaves and 1320 in roots were identified and grouped into five and four clusters, respectively. A SKM network analysis further revealed transcription factors potentially governing this H2O2–Ca2+ cross-talk.
Drought is one of the most severe abiotic stresses impacting plant growth, development, and reproduction. Like H2O2, drought triggers extensive transcriptomic reprogramming. In this study, two strongly drought-induced genes, GASA3 and AFP1, were identified. Loss-of-function mutants showed enhanced drought resistance, while constitutive overexpression of either gene led to reduced tolerance. The gasa3afpl double mutant exhibited even greater resistance than single mutants. Both genes are also ABA-inducible, though GASA3 expression remained low in the absence of AFP1. The improved drought tolerance in mutants was linked to higher leaf water content due to smaller stomatal apertures and reduced transpiration. Additionally, ABA levels were elevated in mutants under drought stress- not due to increased biosynthesis, but via the release of conjugated vacuolar ABA-GE through β-glucosidase BG2. Consistent with this, ABA-responsive genes such as RD29A/B and ABF2/3 were more strongly upregulated in mutants than in wild type (WT). Conversely, PP2CA, which encodes a phosphatase involved in ABA negative feedback, was repressed in the absence of GASA3 and AFP1. These results suggest that both genes act as negative regulators of drought tolerance, with AFP1 influencing GASA3 expression.
Altogether, this thesis offers new insights into plant abiotic stress responses and provides a foundation for future functional studies in barley and other crops, potentially guiding breeding strategies for improved stress resilience under changing climates
Can subcellular organization be explained only by physical principles?
No full textIn a recent forum article, Dan Needleman and Jan Brugues argue that, despite the astonishing advances in cell biology, a fundamental understanding of even the most well-studied subcellular biological processes is lacking. This lack of understanding is evidenced by our inability to make precise predictions of subcellular and cellular behaviors. They suggest that to achieve such an under- standing, we need to apply a combination of quantitative experiments with new theoretical concepts and determine the physical principles of subcellular biological organization. We discuss these issues and suggest that, besides biophysics, we need strong theoretical inputs from biocommunication theory in order to understand all the core agents of the cellular life and subcellular organization
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