Background Salt stress is one of the main constraints determining crop productivity, and therefor... more Background Salt stress is one of the main constraints determining crop productivity, and therefore one of the main limitations for food production. The aim of this study was to characterize the salt stress response at the physiological and molecular level of different Broccoli (Brassica oleracea L. var. Italica Plenck) cultivars that were previously characterized in field and greenhouse trials as salt sensitive or salt tolerant. This study aimed to identify functional and molecular traits capable of predicting the ability of uncharacterized lines to cope with salt stress. For this purpose, this study measured different physiological parameters, hormones and metabolites under control and salt stress conditions. Results This study found significant differences among cultivars for stomatal conductance, transpiration, methionine, proline, threonine, abscisic acid, jasmonic acid and indolacetic acid. Salt tolerant cultivars were shown to accumulate less sodium and potassium in leaves and...
Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for... more Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker’s yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive struc...
Izh2 acts as an integrator of intra- and extracellular signals. It dispatches a single input sign... more Izh2 acts as an integrator of intra- and extracellular signals. It dispatches a single input signal – a change in extracellular Zn concentration – into regulatory networks of several cellular processes, whereby it acts as the second line of cellular adaptation to perturbations to zinc homeostasis.
Maintenance of monovalent cation homeostasis (mainly K(+) and Na(+)) is vital for cell survival, ... more Maintenance of monovalent cation homeostasis (mainly K(+) and Na(+)) is vital for cell survival, and cation toxicity is at the basis of a myriad of relevant phenomena, such as salt stress in crops and diverse human diseases. Full understanding of the importance of monovalent cations in the biology of the cell can only be achieved from a systemic perspective. Translucent is a multinational project developed within the context of the SysMO (System Biology of Microorganisms) initiative and focussed in the study of cation homeostasis using the well-known yeast Saccharomyces cerevisiae as a model. The present review summarize how the combination of biochemical, genetic, genomic and computational approaches has boosted our knowledge in this field, providing the basis for a more comprehensive and coherent vision of the role of monovalent cations in the biology of the cell.
Intracellular pH and K + concentrations must be tightly controlled because they affect many cellu... more Intracellular pH and K + concentrations must be tightly controlled because they affect many cellular activities, including cell growth and death. The mechanisms of homeostasis of H + and K + are only partially understood. In the yeast Saccharomyces cerevisiae , proton efflux is mediated by the Pma1 H + -ATPase. As this pump is electrogenic, the activity of the Trk1 and -2 K + uptake system is crucial for sustained Pma1p operation. The coordinated activities of these two systems determine cell volume, turgor, membrane potential, and pH. Genetic evidence indicates that Trk1p is activated by the Hal4 and -5 kinases and inhibited by the Ppz1 and -2 phosphatases, which, in turn, are inhibited by their regulatory subunit, Hal3p. We show that Trk1p, present in plasma membrane “rafts,” physically interacts with Ppz1p, that Trk1p is phosphorylated in vivo, and that its level of phosphorylation increases in ppz1 and -2 mutants. Interestingly, both the interaction with and inhibition of Ppz1p ...
K + transport in living cells must be tightly controlled because it affects basic physiological p... more K + transport in living cells must be tightly controlled because it affects basic physiological parameters such as turgor, membrane potential, ionic strength, and pH. In yeast, the major high-affinity K + transporter, Trk1, is inhibited by high intracellular K + levels and positively regulated by two redundant “ hal otolerance” protein kinases, Sat4/Hal4 and Hal5. Here we show that these kinases are not required for Trk1 activity; rather, they stabilize the transporter at the plasma membrane under low K + conditions, preventing its endocytosis and vacuolar degradation. High concentrations (0.2 M) of K + , but not Na + or sorbitol, transported by undefined low-affinity systems, maintain Trk1 at the plasma membrane in the hal4 hal5 mutant. Other nutrient transporters, such as Can1 (arginine permease), Fur4 (uracil permease), and Hxt1 (low-affinity glucose permease), are also destabilized in the hal4 hal5 mutant under low K + conditions and, in the case of Can1, are stabilized by high ...
The phosphatase calcineurin and the kinases Hal4/Hal5 regulate high‐affinity potassium uptake in ... more The phosphatase calcineurin and the kinases Hal4/Hal5 regulate high‐affinity potassium uptake in Saccharomyces cerevisiae through the Trk1 transporter. We demonstrate that calcineurin is necessary for high‐affinity potassium uptake even in the absence of Na+ stress. HAL5 expression is induced in response to stress in a calcineurin–dependent manner through a newly identified functional CDRE (nt −195/−189). Lack of calcineurin decreases Hal5 protein levels, although with little effect on Trk1 amounts. However, the growth defect of cnb1 cells at K+‐limiting conditions can be rescued in part by overexpression of HAL5, and this mutation further aggravates the potassium requirements of a hal4 strain. This suggests that the control exerted by calcineurin on Hal5 expression may be biologically relevant for Trk1 regulation.
Background Salt stress is one of the main constraints determining crop productivity, and therefor... more Background Salt stress is one of the main constraints determining crop productivity, and therefore one of the main limitations for food production. The aim of this study was to characterize the salt stress response at the physiological and molecular level of different Broccoli (Brassica oleracea L. var. Italica Plenck) cultivars that were previously characterized in field and greenhouse trials as salt sensitive or salt tolerant. This study aimed to identify functional and molecular traits capable of predicting the ability of uncharacterized lines to cope with salt stress. For this purpose, this study measured different physiological parameters, hormones and metabolites under control and salt stress conditions. Results This study found significant differences among cultivars for stomatal conductance, transpiration, methionine, proline, threonine, abscisic acid, jasmonic acid and indolacetic acid. Salt tolerant cultivars were shown to accumulate less sodium and potassium in leaves and...
Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for... more Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker’s yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive struc...
Izh2 acts as an integrator of intra- and extracellular signals. It dispatches a single input sign... more Izh2 acts as an integrator of intra- and extracellular signals. It dispatches a single input signal – a change in extracellular Zn concentration – into regulatory networks of several cellular processes, whereby it acts as the second line of cellular adaptation to perturbations to zinc homeostasis.
Maintenance of monovalent cation homeostasis (mainly K(+) and Na(+)) is vital for cell survival, ... more Maintenance of monovalent cation homeostasis (mainly K(+) and Na(+)) is vital for cell survival, and cation toxicity is at the basis of a myriad of relevant phenomena, such as salt stress in crops and diverse human diseases. Full understanding of the importance of monovalent cations in the biology of the cell can only be achieved from a systemic perspective. Translucent is a multinational project developed within the context of the SysMO (System Biology of Microorganisms) initiative and focussed in the study of cation homeostasis using the well-known yeast Saccharomyces cerevisiae as a model. The present review summarize how the combination of biochemical, genetic, genomic and computational approaches has boosted our knowledge in this field, providing the basis for a more comprehensive and coherent vision of the role of monovalent cations in the biology of the cell.
Intracellular pH and K + concentrations must be tightly controlled because they affect many cellu... more Intracellular pH and K + concentrations must be tightly controlled because they affect many cellular activities, including cell growth and death. The mechanisms of homeostasis of H + and K + are only partially understood. In the yeast Saccharomyces cerevisiae , proton efflux is mediated by the Pma1 H + -ATPase. As this pump is electrogenic, the activity of the Trk1 and -2 K + uptake system is crucial for sustained Pma1p operation. The coordinated activities of these two systems determine cell volume, turgor, membrane potential, and pH. Genetic evidence indicates that Trk1p is activated by the Hal4 and -5 kinases and inhibited by the Ppz1 and -2 phosphatases, which, in turn, are inhibited by their regulatory subunit, Hal3p. We show that Trk1p, present in plasma membrane “rafts,” physically interacts with Ppz1p, that Trk1p is phosphorylated in vivo, and that its level of phosphorylation increases in ppz1 and -2 mutants. Interestingly, both the interaction with and inhibition of Ppz1p ...
K + transport in living cells must be tightly controlled because it affects basic physiological p... more K + transport in living cells must be tightly controlled because it affects basic physiological parameters such as turgor, membrane potential, ionic strength, and pH. In yeast, the major high-affinity K + transporter, Trk1, is inhibited by high intracellular K + levels and positively regulated by two redundant “ hal otolerance” protein kinases, Sat4/Hal4 and Hal5. Here we show that these kinases are not required for Trk1 activity; rather, they stabilize the transporter at the plasma membrane under low K + conditions, preventing its endocytosis and vacuolar degradation. High concentrations (0.2 M) of K + , but not Na + or sorbitol, transported by undefined low-affinity systems, maintain Trk1 at the plasma membrane in the hal4 hal5 mutant. Other nutrient transporters, such as Can1 (arginine permease), Fur4 (uracil permease), and Hxt1 (low-affinity glucose permease), are also destabilized in the hal4 hal5 mutant under low K + conditions and, in the case of Can1, are stabilized by high ...
The phosphatase calcineurin and the kinases Hal4/Hal5 regulate high‐affinity potassium uptake in ... more The phosphatase calcineurin and the kinases Hal4/Hal5 regulate high‐affinity potassium uptake in Saccharomyces cerevisiae through the Trk1 transporter. We demonstrate that calcineurin is necessary for high‐affinity potassium uptake even in the absence of Na+ stress. HAL5 expression is induced in response to stress in a calcineurin–dependent manner through a newly identified functional CDRE (nt −195/−189). Lack of calcineurin decreases Hal5 protein levels, although with little effect on Trk1 amounts. However, the growth defect of cnb1 cells at K+‐limiting conditions can be rescued in part by overexpression of HAL5, and this mutation further aggravates the potassium requirements of a hal4 strain. This suggests that the control exerted by calcineurin on Hal5 expression may be biologically relevant for Trk1 regulation.
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Papers by Lynne Yenush