Na+/H+ exchange in the halophyte Mesembryanthemum crystallinum is associated with cellular sites of Na+ storage

2002 ◽  
Vol 29 (9) ◽  
pp. 1017 ◽  
Author(s):  
Bronwyn J. Barkla ◽  
Rosario Vera-Estrella ◽  
Jesus Camacho-Emiterio ◽  
Omar Pantoja
Keyword(s):  
Salt Tolerance ◽  
Mesembryanthemum Crystallinum ◽  
Protein Levels ◽  
Key Enzyme ◽  
Plant Vacuoles ◽  
Leaf Tissues ◽  
Bladder Cells ◽  
Plant Salt Tolerance ◽  
Vacuolar Sequestration

The tonoplast Na+/H+ exchanger is involved in sequestering Na+ in plant vacuoles, providing solutes for osmotic adjustment while avoiding cytoplasmic Na+ toxicity. As such it is assumed to be one of the key mechanisms involved in salt-tolerance in plants. In this study, we measured tonoplast Na+/H+ exchange in roots and different leaf tissues of adult Mesembryanthemum crystallinum L. plants to determine if activity of the exchanger follows the gradient from roots to leaves previously observed for Na+ and pinitol accumulation. Na+/H+ exchange was absent from roots of control and NaCl-treated plants. In contrast, leaves showed constitutive Na+/H+ exchange that was enhanced by growth of the plants in NaCl. Highest activity was measured in the epidermal bladder cells in agreement with the highest concentrations of Na+ found in this tissue. Tonoplast H+-translocating ATPase activity was also greatest in this tissue, as were protein levels for myo-inositol-O-methyltransferase, a key enzyme in the pinitol biosynthesis pathway. The strong correlation between Na+/H+ exchange and Na+ accumulation confirms the role of this transporter in vacuolar sequestration of Na+ and plant salt tolerance.

The nuclear retinoid-related orphan receptor-α regulates adipose tissue glyceroneogenesis in addition to hepatic gluconeogenesis

2015 ◽  
Vol 309 (2) ◽  
pp. E105-E114 ◽  
Author(s):  
Sarah Kadiri ◽  
Chloé Monnier ◽  
Munkhzul Ganbold ◽  
Tatiana Ledent ◽  
Jacqueline Capeau ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Glucose Production ◽  
Orphan Receptor ◽  
Hepatic Gluconeogenesis ◽  
Protein Levels ◽  
Key Enzyme ◽  
Fasting Hypoglycemia ◽  
Deficient Mice

Circadian rhythms have an essential role in feeding behavior and metabolism. RORα is a nuclear receptor involved in the interface of the circadian system and metabolism. The adipocyte glyceroneogenesis pathway derives free fatty acids (FFA) liberated by lipolysis to reesterification into triglycerides, thus regulating FFA homeostasis and fat mass. Glyceroneogenesis shares with hepatic gluconeogenesis the key enzyme phospho enolpyruvate carboxykinase c (PEPCKc), whose gene is a RORα target in the liver. RORα-deficient mice (staggerer, RORsg/sg ) have been shown to exhibit a lean phenotype and fasting hypoglycemia for unsolved reasons. In the present study, we investigated whether adipocyte glyceroneogenesis might also be a target pathway of RORα, and we further evaluated the role of RORα in hepatocyte gluconeogenesis. In vivo investigations comparing RORsg/sg mice with their wild-type (WT) littermates under fasting conditions demonstrated that, in the absence of RORα, the release of FFA into the bloodstream was altered and the rise in glycemia in response to pyruvate reduced. The functional analysis of each pathway, performed in adipose tissue or liver explants, confirmed the impairment of adipocyte glyceroneogenesis and liver gluconeogenesis in the RORsg/sg mice; these reductions of FFA reesterification or glucose production were associated with decreases in PEPCKc mRNA and protein levels. Treatment of explants with RORα agonist or antagonist enhanced or inhibited these pathways, respectively, in tissues isolated from WT but not RORsg/sg mice. Our results indicated that both adipocyte glyceroneogenesis and hepatocyte gluconeogenesis were regulated by RORα. This study demonstrates the physiological function of RORα in regulating both glucose and FFA homeostasis.

scholarly journals Regulation of CYP94B1 by WRKY33 controls apoplastic barrier formation in the roots leading to salt tolerance

2020 ◽  
Author(s):  
Pannaga Krishnamurthy ◽  
Bhushan Vishal ◽  
Wan Jing Ho ◽  
Felicia Chien Joo Lok ◽  
Felicia Si Min Lee ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Chromatin Immunoprecipitation ◽  
Histochemical Staining ◽  
P450 Gene ◽  
Upstream Regulator ◽  
Barrier Formation ◽  
Apoplastic Barrier ◽  
Plant Salt Tolerance ◽  
Endodermal Cells

AbstractSalinity is an environmental stress that causes decline in crop yield. Avicennia officinalis and other mangroves have adaptations such as ultrafiltration at the roots aided by apoplastic cell-wall barriers to thrive in saline conditions. We studied a Cytochrome P450 gene, AoCYP94B1 from A. officinalis and its Arabidopsis ortholog AtCYP94B1 that are involved in apoplastic barrier formation, and are induced by 30 minutes of salt treatment in the roots. Heterologous expression of AoCYP94B1 in atcyp94b1 Arabidopsis mutant and wild-type rice conferred increased NaCl tolerance to seedlings by enhancing root suberin deposition. Histochemical staining and GC-MS/MS quantification of suberin precursors confirmed the role of CYP94B1 in suberin biosynthesis. Using chromatin immunoprecipitation, yeast one-hybrid and luciferase assays, we identified AtWRKY33 as the upstream regulator of AtCYP94B1 in Arabidopsis. In addition, atwrky33 mutants exhibited reduced suberin and salt sensitive phenotypes, which were rescued by expressing 35S::AtCYP94B1 in atwrky33 mutant. This further confirms that the regulation of AtCYP94B1 by AtWRKY33 is part of the salt tolerance mechanism, and our findings can help in generating salt tolerant crops.One sentence summaryAtWRKY33 transcription factor regulates AtCYP94B1 to increase plant salt tolerance by enhanced suberin deposition in the endodermal cells of Arabidopsis roots

Improvement of Torenia fournieri salinity tolerance by expression of Arabidopsis AtNHX5

2008 ◽  
Vol 35 (3) ◽  
pp. 185 ◽  
Author(s):  
Le-Yi Shi ◽  
Hong-Qing Li ◽  
Xiao-Ping Pan ◽  
Guo-Jiang Wu ◽  
Mei-Ru Li
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Potential Role ◽  
Ion Homeostasis ◽  
Leaf Explants ◽  
Wild Type ◽  
Torenia Fournieri ◽  
Regenerated Plants ◽  
Plant Salt Tolerance

In this paper, transgenic torenia plants expressing the AtNHX5 gene from Arabidopsis in sense and antisense orientations were produced to examine the potential role of AtNHX5 in plant salt tolerance and development. We found that torenia plants overexpressing AtNHX5 showed markedly enhanced tolerance to salt stress compared with both wild-type and antisense AtNHX5 transgenic plants upon salt stress. Measurements of ion levels indicated that Na+ and K+ contents were all higher in AtNHX5 overexpressing shoots than in those of both wild-type and antisense AtNHX5 shoots treated with 50 mm NaCl. This indicated that overexpression of AtNHX5 could improve the salt tolerance of transgenic torenia via accumulation of both Na+ and K+ in shoots, in which overall ion homeostasis and osmotic adjustment was changed to sustain the increase in shoot salt tolerance. Further, we found that overexpression of AtNHX5 in torenia significantly improved the shoot regeneration frequency in leaf explants and increased the plantlet survival rate when transferring the regenerated plants to soil. In addition, the AtNHX5 expressing plants produced flowers earlier than both wild-type and the antisense AtNHX5 plants. Taken together, the results indicated that AtNHX5 functions not only in plant salt tolerance but also in plant growth and development.

scholarly journals Isocitrate lyase plays important roles in plant salt tolerance

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Worawat Yuenyong ◽  
Supaart Sirikantaramas ◽  
Li-Jia Qu ◽  
Teerapong Buaboocha
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Transgenic Arabidopsis ◽  
Isocitrate Lyase ◽  
Glyoxylate Cycle ◽  
Knockout Mutant ◽  
Encoding Gene ◽  
Plant Salt Tolerance ◽  
The Glyoxylate Cycle

Abstract Background Isocitrate lyase (ICL) is a key enzyme in the glyoxylate cycle. In a previous study in rice, the expression of the ICL-encoding gene (OsICL) was highly induced by salt stress and its expression was enhanced in transgenic rice lines overexpressing OsCam1–1, a calmodulin (CaM)-encoding gene. CaM has been implicated in salt tolerance mechanisms in plants; however, the cellular mechanisms mediated by CaM are not clearly understood. In this study, the role of OsICL in plant salt tolerance mechanisms and the possible involvement of CaM were investigated using transgenic plants expressing OsICL or OsCam1–1. Results OsICL was highly expressed in senesced leaf and significantly induced by salt stress in three OsCam1–1 overexpressing transgenic rice lines as well as in wild type (WT). In WT young leaf, although OsICL expression was not affected by salt stress, all three transgenic lines exhibited highly induced expression levels. In Arabidopsis, salt stress had negative effects on germination and seedling growth of the AtICL knockout mutant (Aticl mutant). To examine the roles of OsICL we generated the following transgenic Arabidopsis lines: the Aticl mutant expressing OsICL driven by the native AtICL promoter, the Aticl mutant overexpressing OsICL driven by the 35SCaMV promoter, and WT overexpressing OsICL driven by the 35SCaMV promoter. Under salt stress, the germination rate and seedling fresh and dry weights of the OsICL-expressing lines were higher than those of the Aticl mutant, and the two lines with the icl mutant background were similar to the WT. The Fv/Fm and temperature of rosette leaves in the OsICL-expressing lines were less affected by salt stress than they were in the Aticl mutant. Finally, glucose and fructose contents of the Aticl mutant under salt stress were highest, whereas those of OsICL-expressing lines were similar to or lower than those of the WT. Conclusions OsICL, a salt-responsive gene, was characterized in the transgenic Arabidopsis lines, revealing that OsICL expression could revert the salt sensitivity phenotypes of the Aticl knockout mutant. This work provides novel evidence that supports the role of ICL in plant salt tolerance through the glyoxylate cycle and the possible involvement of OsCam1–1 in regulating its transcription.

scholarly journals Proteomics of Homeobox7 Enhanced Salt Tolerance in Mesembryanthemum crystallinum

2021 ◽  
Vol 22 (12) ◽  
pp. 6390
Author(s):  
Xuemei Zhang ◽  
Bowen Tan ◽  
Dan Zhu ◽  
Daniel Dufresne ◽  
Tingbo Jiang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Salt Tolerance ◽  
Transgenic Plants ◽  
Mesembryanthemum Crystallinum ◽  
Plant Leaves ◽  
Wild Type ◽  
Salt Treatment ◽  
Ice Plant ◽  
Positive Role ◽  
Plant Salt Tolerance

Mesembryanthemum crystallinum (common ice plant) is a halophyte species that has adapted to extreme conditions. In this study, we cloned a McHB7 transcription factor gene from the ice plant. The expression of McHB7 was significantly induced by 500 mM NaCl and it reached the peak under salt treatment for 7 days. The McHB7 protein was targeted to the nucleus. McHB7-overexpressing in ice plant leaves through Agrobacterium-mediated transformation led to 25 times more McHB7 transcripts than the non-transformed wild type (WT). After 500 mM NaCl treatment for 7 days, the activities of superoxide dismutase (SOD) and peroxidase (POD) and water content of the transgenic plants were higher than the WT, while malondialdehyde (MDA) was decreased in the transgenic plants. A total of 1082 and 1072 proteins were profiled by proteomics under control and salt treatment, respectively, with 22 and 11 proteins uniquely identified under control and salt stress, respectively. Among the 11 proteins, 7 were increased and 4 were decreased after salt treatment. Most of the proteins whose expression increased in the McHB7 overexpression (OE) ice plants under high salinity were involved in transport regulation, catalytic activities, biosynthesis of secondary metabolites, and response to stimulus. The results demonstrate that the McHB7 transcription factor plays a positive role in improving plant salt tolerance.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

2006 ◽  
Vol 76 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yukari Egashira ◽  
Shin Nagaki ◽  
Hiroo Sanada
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Enzyme Activities ◽  
Treated Group ◽  
Control Group ◽  
Puromycin Aminonucleoside ◽  
Low Level ◽  
Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

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