scholarly journals Role of active transport of potassium to leaves in the mechanisms of tolerance to salinity in common bean (Phaseolus vulgaris L.)

2020 ◽  
Vol 12 (2) ◽  
pp. 447-459
Author(s):  
Sugenith ARTEAGA ◽  
Monica BOSCAIU ◽  
Jaime PROHENS ◽  
Oscar VICENTE

Biochemical markers are of great utility in screening for salt tolerance of crops. In common beans (Phaseolus vulgaris), lower levels of proline under stress have been associated with a better stress resistance of cultivars. In the present study, the responses to salinity have been analysed in six cultivars of common beans: four local landraces from Spain and two experimental lines from Cuba. Proline was used for ranking the relative tolerance of the cultivars, confirming a previous study which reported as more stress-tolerant two of the Spanish landraces. Total soluble sugars concentrations varied with treatments and between genotypes, but it was difficult to assess their role in stress tolerance of the analysed plants. Sodium concentration in leaves was the lowest in one of the two salt-resistant cultivars, and potassium did not vary or even increased under salt stress in all of them, except for the most susceptible one, where a drop of this cation was registered under 150 mM NaCl. Changes in malondialdehyde (MDA) contents did not indicate salt-induced membrane peroxidation resulting from secondary oxidative stress; consequently, accumulation of total phenolic compounds and flavonoids, as an antioxidant defence mechanism, was not detected. These results highlight the reliability of using proline as a biochemical marker of salt stress in common beans and the importance of the mechanism related to potassium transport to leaves in conferring stress tolerance to some common bean cultivars.

Agronomy ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 409
Author(s):  
Yu ◽  
Yu ◽  
Hou ◽  
Zhang ◽  
Guo ◽  
...  

The common bean (Phaseolus vulgaris L.), the most important food legume for human nutrition globally, contributes greatly to the improvement of soil fertility in semi-dry lands where most of the soil is already salinized or alkalized, such as in the Songnen Plain of China. In this study, we investigated the effects of salt stress (neutral and alkaline) on the salt-tolerant common bean. Seed germination, seedling growth, photosynthesis, and osmotic adjustment were assessed. Neutral and alkaline salt growth environments were simulated using NaCl and NaHCO3, respectively. The results indicated that at ≥60 mmol·L−1, both NaCl and NaHCO3 caused significant delays in seedling emergence and decreased seedling emergence rates. NaHCO3 stress suppressed seedling survival regardless of concentration; however, only NaCl concentrations >60 mmol·L−1 had the same effect. Alkaline salt stress remarkably suppressed photosynthesis and seedling establishment. The common bean compensated for the increase in inorganic anion concentration (influx of Na+) by synthesizing more organic acids and soluble sugars. This adaptive mechanism enabled the common bean to balance the large inflow of cations for maintaining a stable cell pH environment under alkaline salt stress.


PLoS ONE ◽  
2018 ◽  
Vol 13 (7) ◽  
pp. e0200566 ◽  
Author(s):  
Chantal Ebel ◽  
Asma BenFeki ◽  
Moez Hanin ◽  
Roberto Solano ◽  
Andrea Chini

Author(s):  
Dinesh Kumar ◽  
Mohamad Al Hassan ◽  
Oscar Vicente ◽  
Veena Agrawal ◽  
Monica Boscaiu

Elucidating the mechanisms of abiotic stress tolerance in different species will help to develop more resistant plant varieties, contributing to improve agricultural production in a climate change scenario. Basic responses to salt stress, dependent on osmolyte accumulation and activation of antioxidant systems, have been studied in Nerium oleander, a xerophytic species widely used as ornamental. Salt strongly inhibited growth, but the plants survived one-month treatments with quite high NaCl concentrations, up to 800 mM, indicating the the species is relatively resistant to salt stress, in addition to drought. Levels of proline, glycine betaine and soluble sugars increased only slightly in the presence of salt; however, soluble sugar absolute contents were much higher than those of the other osmolytes, suggesting a functional role of these compounds in osmotic adjustment, and the presence of constitutive mechanisms of response to salt stress. High salinity generated oxidative stress in the plants, as shown by the increase of malondialdehyde levels. Antioxidant systems, enzymatic and non-enzymatic, are generally activated in response to salt stress; in oleander, they do not seem to include total phenolics or flavonoids, antioxidant compounds which did not accumulate significantly in salt-trated plants


2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 24-24
Author(s):  
David Fonseca Hernandez ◽  
Ignacio Orozco-Avila ◽  
Eugenia Lugo-Cervantes ◽  
Luis Mojica

Abstract Objectives The objective of this work was to evaluate the potential of common bean phenolic extract to exert anti-aging and antioxidant effect by inhibiting the collagenase, elastase, tyrosinase enzymes and free radicals. Methods 18 varieties of common bean (Phaseolus vulgaris L.) from Chiapas, Mexico, were analyzed for total phenolic content (TPC) and total anthocyanin content (ACN). Supercritical fluid (SCF) and leaching extractions were used for phenolic compounds extraction. Antioxidant capacity was evaluated using DPPH and ABTS scavenging assay. The inhibitory potential of the extract was evaluated for tyrosinase from mushroom, collagenase type-1 from Clostridium histolycum and elastase from porcine pancreas enzymes. Results The TPC ranged from 3.8–34.33 mg GAE/g coat and ACN ranged from 0.04–9.41 mg C3GE/g coat among the 18 common bean varieties (P < 0.05). The cultivar selected for this study was black bean with a TPC of 27.45 ± 0.7 mg GAE/g coat and ACN of 5.3 ± 0.1 mg C3GE/g coat. The best extraction conditions for the obtention of phenolic compounds and anthocyanins were SCF water-ethanol 50% as cosolvent, obtaining 66.60 ± 7.4 mg GAE/g coat (TPC) and 7.3 ± 0.6 mg C3GE/g coat (ACN). TPC and ACN content between each extraction process were statistically different (P < 0.05). For DPPH scavenging assay the IC50 for the black bean extract was 0.32 ± 0.01 mg GAE/g coat, and 0.40 ± 0.03 mg GAE/g coat for ABTS assay. Finally, the IC50 for the enzymatic inhibition assays of tyrosinase, collagenase and elastase were 10.44 ± 1.32, 8.33 ± 0.65 and 0.11 ± 0.02 mg GAE/g coat, respectively. Conclusions Black bean (Phaseolus vulgaris L.) extract presents high antioxidant capacity and inhibitory potential for tyrosinase and metalloproteinases such as collagenase and elastase. Black bean phenolic extracts could be used in cosmeceutical products related to preventing oxidative stress and aging. Funding Sources Author David Fonseca Hernández was supported by a scholarship from Consejo Nacional de Ciencia y Tecnología CONACyT-México, number 901,000. CONACYT-FORDECYT GRANT.


Plants ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 834
Author(s):  
Abel Lidón-Soto ◽  
Eva Núñez-Delegido ◽  
Iván Pastor-Martínez ◽  
Pedro Robles ◽  
Víctor Quesada

Plastid gene expression (PGE) must adequately respond to changes in both development and environmental cues. The transcriptional machinery of plastids in land plants is far more complex than that of prokaryotes. Two types of DNA-dependent RNA polymerases transcribe the plastid genome: a multimeric plastid-encoded polymerase (PEP), and a monomeric nuclear-encoded polymerase (NEP). A single NEP in monocots (RPOTp, RNA polymerase of the T3/T7 phage-type) and two NEPs in dicots (plastid-targeted RPOTp, and plastid- and mitochondrial-targeted RPOTmp) have been hitherto identified. To unravel the role of PGE in plant responses to abiotic stress, we investigated if Arabidopsis RPOTp could function in plant salt tolerance. To this end, we studied the sensitivity of T-DNA mutants scabra3-2 (sca3-2) and sca3-3, defective in the RPOTp gene, to salinity, osmotic stress and the phytohormone abscisic acid (ABA) required for plants to adapt to abiotic stress. sca3 mutants were hypersensitive to NaCl, mannitol and ABA during germination and seedling establishment. Later in development, sca3 plants displayed reduced sensitivity to salt stress. A gene ontology (GO) analysis of the nuclear genes differentially expressed in the sca3-2 mutant (301) revealed that many significantly enriched GO terms were related to chloroplast function, and also to the response to several abiotic stresses. By quantitative RT-PCR (qRT-PCR), we found that genes LHCB1 (LIGHT-HARVESTING CHLOROPHYLL a/b-BINDING1) and AOX1A (ALTERNATIVE OXIDASE 1A) were respectively down- and up-regulated in the Columbia-0 (Col-0) salt-stressed plants, which suggests the activation of plastid and mitochondria-to-nucleus retrograde signaling. The transcript levels of genes RPOTp, RPOTmp and RPOTm significantly increased in these salt-stressed seedlings, but this enhanced expression did not lead to the up-regulation of the plastid genes solely transcribed by NEP. Similar to salinity, carotenoid inhibitor norflurazon (NF) also enhanced the RPOTp transcript levels in Col-0 seedlings. This shows that besides salinity, inhibition of chloroplast biogenesis also induces RPOTp expression. Unlike salt and NF, the NEP genes were significantly down-regulated in the Col-0 seedlings grown in ABA-supplemented media. Together, our findings demonstrate that RPOTp functions in abiotic stress tolerance, and RPOTp is likely regulated positively by plastid-to-nucleus retrograde signaling, which is triggered when chloroplast functionality is perturbed by environmental stresses, e.g., salinity or NF. This suggests the existence of a compensatory mechanism, elicited by impaired chloroplast function. To our knowledge, this is the first study to suggest the role of a nuclear-encoded plastid-RNA polymerase in salt stress tolerance in plants.


2000 ◽  
Vol 20 (24) ◽  
pp. 9262-9270 ◽  
Author(s):  
Jun Imai ◽  
Ichiro Yahara

ABSTRACT The role of HSP90 in stress tolerance was investigated inSaccharomyces cerevisiae. Cells showing 20-fold overexpression of Hsc82, an HSP90 homologue in yeast, were hypersensitive to high-NaCl or H-LiCl stresses. Hsc82-overexpressing cells appeared similar to calcineurin-defective cells in salt sensitivity and showed reduced levels of calcineurin-dependent gene expression. Co-overexpression of Cna2, the catalytic subunit of calcineurin, suppressed the hypersensitivity. Cna2 and Hsc82 coimmunoprecipitated from control cells grown under normal conditions but not from stressed cells. In contrast, coimmunoprecipitation was detected with Hsc82-overexpressing cells even after exposure to stresses. Cna2 immune complexes from stressed control cells showed a significant level of calcineurin activity, whereas those from stressed Hsc82-overexpressing cells did not. Treatment of extracts from Hsc82-overexpressing cells with Ca2+-calmodulin increased the calcineurin activity associated with Cna2 immune complexes. Geldanamycin, an inhibitor of HSP90 abolished the coimmunoprecipitation but did not activate calcineurin. When the expression level of Hsc82 decreased to below 30% of the normal level, cells also became hypersensitive to salt stress. In these cells, the amount of Cna2 was reduced, likely as a result of degradation. The present results showed that Hsc82 binds to and stabilizes Cna2 and that dissociation of Cna2 from Hsc82 is necessary for its activation.


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