Papers by Vanesa Tognetti
Plants, Dec 18, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Molecular Sciences, Jul 4, 2017
Plant growth and development are critically influenced by unpredictable abiotic factors. To survi... more Plant growth and development are critically influenced by unpredictable abiotic factors. To survive fluctuating changes in their environments, plants have had to develop robust adaptive mechanisms. The dynamic and complementary actions of the auxin and cytokinin pathways regulate a plethora of developmental processes, and their ability to crosstalk makes them ideal candidates for mediating stress-adaptation responses. Other crucial signaling molecules responsible for the tremendous plasticity observed in plant morphology and in response to abiotic stress are reactive oxygen species (ROS). Proper temporal and spatial distribution of ROS and hormone gradients is crucial for plant survival in response to unfavorable environments. In this regard, the convergence of ROS with phytohormone pathways acts as an integrator of external and developmental signals into systemic responses organized to adapt plants to their environments. Auxin and cytokinin signaling pathways have been studied extensively. Nevertheless, we do not yet understand the impact on plant stress tolerance of the sophisticated crosstalk between the two hormones. Here, we review current knowledge on the function of auxin and cytokinin in redirecting growth induced by abiotic stress in order to deduce their potential points of crosstalk.
Frontiers in Plant Science, 2018
Leaf senescence is a concerted physiological process involving controlled degradation of cellular... more Leaf senescence is a concerted physiological process involving controlled degradation of cellular structures and reallocation of breakdown products to other plant organs. It is accompanied by increased production of reactive oxygen species (ROS) that are proposed to signal cell death, although both the origin and the precise role of ROS in the execution of this developmental program are still poorly understood. To investigate the contribution of chloroplast-associated ROS to natural leaf senescence, we used tobacco plants expressing a plastid-targeted flavodoxin, an electron shuttle flavoprotein present in prokaryotes and algae. When expressed in plants, flavodoxin specifically prevents ROS formation in chloroplasts during stress situations. Senescence symptoms were significantly mitigated in these transformants, with decreased accumulation of chloroplastic ROS and differential preservation of chlorophylls, carotenoids, protein contents, cell and chloroplast structures, membrane integrity and cell viability. Flavodoxin also improved maintenance of chlorophyll-protein complexes, photosynthetic electron flow, CO 2 assimilation, central metabolic routes and levels of bioactive cytokinins and auxins in aging leaves. Delayed induction of senescence-associated genes indicates that the entire genetic program of senescence was affected by flavodoxin. The results suggest that ROS generated in chloroplasts are involved in the regulation of natural leaf senescence.
The Plant Journal, 2007
SummaryPlant defense against pathogens often includes rapid programmed cell death known as the hy... more SummaryPlant defense against pathogens often includes rapid programmed cell death known as the hypersensitive response (HR). Recent genetic studies have demonstrated the involvement of a specific mitogen‐activated protein kinase (MAPK) cascade consisting of three tobacco MAPKs, SIPK, Ntf4 and WIPK, and their common upstream MAPK kinase (MAPKK or MEK), NtMEK2. Potential upstream MAPKK kinases (MAPKKKs or MEKKs) in this cascade include the orthologs of Arabidopsis MEKK1 and tomato MAPKKKα. Activation of the SIPK/Ntf4/WIPK pathway induces cell death with phenotypes identical to pathogen‐induced HR at macroscopic, microscopic and physiological levels, including loss of membrane potential, electrolyte leakage and rapid dehydration. Loss of membrane potential in NtMEK2DD plants is associated with the generation of reactive oxygen species (ROS), which is preceded by disruption of metabolic activities in chloroplasts and mitochondria. We observed rapid shutdown of carbon fixation in chlorop...
Plant and Cell Physiology, Jan 22, 2019
Abiotic stress poses constant challenges for plant survival and is a serious problem for global a... more Abiotic stress poses constant challenges for plant survival and is a serious problem for global agricultural productivity. On a molecular level, stress conditions result in elevation of reactive oxygen species (ROS) production causing oxidative stress associated with oxidation of proteins and nucleic acids as well as impairment of membrane functions. Adaptation of root growth to ROS accumulation is facilitated through modification of auxin and cytokinin hormone homeostasis. Here, we report that in Arabidopsis root meristem, ROSinduced changes of auxin levels correspond to decreased abundance of PIN auxin efflux carriers at the plasma membrane (PM). Specifically, increase in H 2 O 2 levels affects PIN2 endocytic recycling. We show that the PIN2 intracellular trafficking during adaptation to oxidative stress requires the function of the ADP-ribosylation factor (ARF)-guaninenucleotide exchange factor (GEF) BEN1, an actin-associated regulator of the trafficking from the PM to early endosomes and, presumably, indirectly, trafficking to the vacuoles. We propose that H 2 O 2 levels affect the actin dynamics thus modulating ARF-GEF-dependent trafficking of PIN2. This mechanism provides a way how root growth acclimates to stress and adapts to a changing environment.
International Journal of Molecular Sciences, 2017
Plant growth and development are critically influenced by unpredictable abiotic factors. To survi... more Plant growth and development are critically influenced by unpredictable abiotic factors. To survive fluctuating changes in their environments, plants have had to develop robust adaptive mechanisms. The dynamic and complementary actions of the auxin and cytokinin pathways regulate a plethora of developmental processes, and their ability to crosstalk makes them ideal candidates for mediating stress-adaptation responses. Other crucial signaling molecules responsible for the tremendous plasticity observed in plant morphology and in response to abiotic stress are reactive oxygen species (ROS). Proper temporal and spatial distribution of ROS and hormone gradients is crucial for plant survival in response to unfavorable environments. In this regard, the convergence of ROS with phytohormone pathways acts as an integrator of external and developmental signals into systemic responses organized to adapt plants to their environments. Auxin and cytokinin signaling pathways have been studied exte...
Plant, Cell & Environment, 2017
To maintain the activity of meristems is an absolute requirement for plant growth and development... more To maintain the activity of meristems is an absolute requirement for plant growth and development, and the role of the plant hormones auxin and cytokinin in apical meristem function is well established. Only little attention has been given, however, to the function of the reactive oxygen species (ROS) gradient along meristematic tissues and its interplay with hormonal regulatory networks. The interdependency between auxin-, cytokinin-, and ROS-related circuits controls primary growth and development while modulating plant morphology in response to detrimental environmental factors. Because ROS interaction with redox-active compounds significantly affects the cellular redox gradient, the latter constitutes an interface for crosstalk between hormone and ROS signalling pathways. This review focuses on the mechanisms underlying ROSdependent interactions with redox and hormonal components in shoot and root apical meristems which are crucial for meristems maintenance when plants are exposed to environmental hardships. We also emphasize the importance of cell type and the subcellular compartmentalization of ROS and redox networks to obtain a holistic understanding of how apical meristems adapt to stress.
Molecular Plant, 2014
Hydrogen peroxide (H 2 O 2) operates as a signaling molecule in eukaryotes, but the specificity o... more Hydrogen peroxide (H 2 O 2) operates as a signaling molecule in eukaryotes, but the specificity of its signaling capacities remains largely unrevealed. Here, we analyzed whether a moderate production of H 2 O 2 from two different plant cellular compartments has divergent effects on the plant transcriptome. Arabidopsis thaliana overexpressing glycolate oxidase in the chloroplast (Fahnenstich et al., 2008; Balazadeh et al., 2012) and plants deficient in peroxisomal catalase (Queval et al., 2007; Inzé et al., 2012) were grown under non-photorespiratory conditions and then transferred to photorespiratory conditions to foster the production of H 2 O 2 in both organelles. We show that H 2 O 2 originating in a specific organelle induces two types of responses: one that integrates signals independently from the subcellular site of H 2 O 2 production and another that is dependent on the H 2 O 2 production site. H 2 O 2 produced in peroxisomes induces transcripts involved in protein repair responses, while H 2 O 2 produced in chloroplasts induces early signaling responses, including transcription factors and biosynthetic genes involved in production of secondary signaling messengers. There is a significant bias towards the induction of genes involved in responses to wounding and pathogen attack by chloroplastic-produced H 2 O 2 , including indolic glucosinolates-, camalexin-, and stigmasterol-biosynthetic genes. These transcriptional responses were accompanied by the accumulation of 4-methoxy-indol-3-ylmethyl glucosinolate and stigmasterol.
Plant Physiology, 2015
Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell prolifera... more Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell proliferation and cell expansion. During the proliferation phase, chloroplasts need to divide extensively, and during the transition from cell proliferation to expansion, they differentiate into photosynthetically active chloroplasts, providing the plant with energy. The transcription factor GROWTH REGULATING FACTOR5 (GRF5) promotes the duration of the cell proliferation period during leaf development. Here, it is shown that GRF5 also stimulates chloroplast division, resulting in a higher chloroplast number per cell with a concomitant increase in chlorophyll levels in 35S:GRF5 leaves, which can sustain higher rates of photosynthesis. Moreover, 35S:GRF5 plants show delayed leaf senescence and are more tolerant for growth on nitrogen-depleted medium. Cytokinins also stimulate leaf growth in part by extending the cell proliferation phase, simultaneously delaying the onset of the cell expansion phase...
Plant, Cell & Environment, 2011
Under environmental stresses, plant development is adaptively modulated. This modulation is influ... more Under environmental stresses, plant development is adaptively modulated. This modulation is influenced by the steady-state balance (homeostasis) between reactive oxygen species (ROS) and phytohormones. Frequently observed symptoms in plant stress adaptation responses include growth retardation, reduced metabolism and photosynthesis, reallocation of metabolic resources and increased antioxidant activities to maximize plant survival under adverse environmental conditions. In view of stressinduced morphogenetic changes during adaptation, ROS and auxin are the main players in the regulatory networks because both are strongly affected by exposure to environmental cues. However, the mechanisms underlying the crosstalk between ROS and auxin are poorly understood. In this review, we aim at surveying how the integration of environmental stress-related signals is modulated by crosstalk between ROS and auxin regulatory networks.
Plant and Cell Physiology, 2019
Abiotic stress poses constant challenges for plant survival and is a serious problem for global a... more Abiotic stress poses constant challenges for plant survival and is a serious problem for global agricultural productivity. On a molecular level, stress conditions result in elevation of reactive oxygen species (ROS) production causing oxidative stress associated with oxidation of proteins and nucleic acids as well as impairment of membrane functions. Adaptation of root growth to ROS accumulation is facilitated through modification of auxin and cytokinin hormone homeostasis. Here, we report that in Arabidopsis root meristem, ROSinduced changes of auxin levels correspond to decreased abundance of PIN auxin efflux carriers at the plasma membrane (PM). Specifically, increase in H 2 O 2 levels affects PIN2 endocytic recycling. We show that the PIN2 intracellular trafficking during adaptation to oxidative stress requires the function of the ADP-ribosylation factor (ARF)-guaninenucleotide exchange factor (GEF) BEN1, an actin-associated regulator of the trafficking from the PM to early endosomes and, presumably, indirectly, trafficking to the vacuoles. We propose that H 2 O 2 levels affect the actin dynamics thus modulating ARF-GEF-dependent trafficking of PIN2. This mechanism provides a way how root growth acclimates to stress and adapts to a changing environment.
nbiap.vt.edu
Plants growing under natural conditions unavoidably face episodic situations of environmental str... more Plants growing under natural conditions unavoidably face episodic situations of environmental stress in the course of their life times. They have developed numerous strategies to survive in such adverse conditions. Crops, in contrast, are selected by humans for their high productivity in agriculture, but this is usually not accompanied by increasing resistance to hostile environments. Diseases, unfavorable climates, or inappropriate soils are responsible for most agricultural losses. Analysis of major crops with economically valuable reproductive or vegetative structures (corn, soybeans, barley, potatoes, among others) shows potential record yields 3-to 7-fold greater than average yields 1 .
Plant, Cell & …, Jan 1, 2011
Under environmental stresses, plant development is adaptively modulated. This modulation is influ... more Under environmental stresses, plant development is adaptively modulated. This modulation is influenced by the steady-state balance (homeostasis) between reactive oxygen species (ROS) and phytohormones. Frequently observed symptoms in plant stress adaptation ...
Nature …, Jan 1, 2011
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Trends in Plant …, Jan 1, 2011
Reactive oxygen species (ROS) play a multitude of signaling roles in different organisms from bac... more Reactive oxygen species (ROS) play a multitude of signaling roles in different organisms from bacteria to mammalian cells. They were initially thought to be toxic byproducts of aerobic metabolism, but have now been acknowledged as central players in the complex signaling network of cells. In this review, we will attempt to address several key questions related to the use of ROS as signaling molecules in cells, including the dynamics and specificity of ROS signaling, networking of ROS with other signaling pathways, ROS signaling within and across different cells, ROS waves and the evolution of the ROS gene network.
The Plant Cell …, Jan 1, 2010
Environmental …, Jan 1, 2007
Significant effort has been directed in recent times to the use of plants to extract and detoxify... more Significant effort has been directed in recent times to the use of plants to extract and detoxify nitroaromatics from polluted industrial facilities. We have explored the possibility of overcoming the phytotoxicity of the highly toxic and recalcitrant nitroderivative 2,4-dinitrotoluene (2,4-DNT) by expressing a cyanobacterial flavodoxin (Fld) in tobacco plants. We demonstrate here that transformants accumulating Fld in plastids display a remarkable increase in the ability to tolerate, take up, and transform 2,4-DNT, as compared to their wild-type siblings. We also show that Fld mediates one-electron reduction of 2,4-DNT in the presence of oxygen and especially in anaerobiosis. Moreover, Fld-loaded chloroplasts are able to convert 2,4-DNT into its aminoderivatives in the presence of light. The results suggest that expression of Fld in landscape plants could facilitate effective cleanup of sites contaminated with this class of pollutants.
Trends in …, Jan 1, 2008
Environmental stresses and iron limitation are the primary causes of crop losses worldwide. Engin... more Environmental stresses and iron limitation are the primary causes of crop losses worldwide. Engineering strategies aimed at gaining stress tolerance have focused on overexpression of endogenous genes belonging to molecular networks for stress perception or responses. Based on the typical response of photosynthetic microorganisms to stress, an alternative approach has been recently applied with considerable success. Ferredoxin, a stress-sensitive target, was replaced in tobacco chloroplasts by an isofunctional protein, a cyanobacterial flavodoxin, which is absent in plants. Resulting transgenic lines showed wide-range tolerance to drought, chilling, oxidants, heat and iron starvation. The survival of plants under such adverse conditions would be an enormous agricultural advantage and makes this novel strategy a potentially powerful biotechnological tool for the generation of multiple-tolerant crops in the near future.
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Papers by Vanesa Tognetti