Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0008272 (chlorosis)
 2,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Duckweed (Spirodela oligorrhiza, Kurz) is a sensitive indicator of 1,1'-alkyl-4,4'-bipyridylium salt (viologen) herbicidal potency. A homologous series of viologens were tested to determine relative herbicidal potency which was related to alkyl inductive and steric effects of N-alkyl side chains. Chlorosis was assessed after 48 hr of continuous illumination to establish herbicidal potency. Herbicidally effective concentrations were 2.7, 12, 236, 71, 31, 51, 13 and 43 microM for methyl (paraquat), propyl, isopropyl, butyl, methyl-pentyl, hexyl, octyl and benzyl viologen, respectively. A biphasic relationship of herbicidal potency versus steric effect was established in which compounds with the least bulky side chains were most phytotoxic. Comparison of rat lethality (acute, subcutaneous) and herbicidal potency of these compounds indicates that none of the viologens tested are less toxic to mammals than plants compared to the commercial herbicide methyl biologen (paraquat).
 ...
PMID:Herbicidal potency of 1,1'-alkyl-4,4'-bipyridylium salts as a function of their physicochemical constants in duckweed. 54 22

Leaf discs approximately 8 mm in diameter taken from green and from chlorotic areas of variegated leaves of Coleus were grown in light under sterile conditions in a mineral salt, sucrose, vitamin medium supplemented with auxin and cytokinin. Green shoots, which later formed roots, grew from both green and chlorotic discs in media containing suitable amounts of auxin and cytokinin. None developed in media supplemented with auxin alone or with cytokinin alone. Discs with young plants were transferred to soil. Plants that grew varied widely from those with no chlorosis to those with more chlorosis than the original variety from which the discs were taken. Plants grown from discs taken from green areas of leaves with chlorosis varied in patterns of chlorosis as much as those that grew from discs from chlorotic areas of leaves.
 ...
PMID:Development of plants from leaf discs of variegated Coleus and its relation to patterns of leaf chlorosis. 66 30

A comparative study of selenium (Se) assimilation under the influence of sulfate and chloride salt salinity was conducted on two saltgrass ecotypes. The inland saltgrass grows successfully on the soil contaminated with elevated Se concentrations at Kesterson, Merced County, California. The coastal saltgrass colonizes a tidal salt marsh in Bodega Bay on the coast of California. The saltgrass samples were grown in sand culture and irrigated with quarter concentration of modified Hoagland solution supplemented with different concentrations of Se with or without sulfate or chloride salt. The Bodega Bay plants exhibited greater tolerance to both the sulfate and chloride salinity than the Kesterson plants. The plants of both ecotypes accumulated about 90% of their total tissue Se in the nonprotein fraction. When sulfate was present in the irrigation solution, the Kesterson plants assimilated significantly less Se in its protein and nonprotein fractions than in the Bodega Bay plants. Under Se treatment, chlorosis symptoms were found on the leaves of the Bodega Bay plants, but not on the leaves of the Kesterson plants. The above results demonstrate that the two saltgrasses are distinct ecotypes in respect to their salinity tolerance and the ability of mitigation of selenium assimilation in the presence of sulfate.
 ...
PMID:Selenium assimilation and differential response to elevated sulfate and chloride salt concentrations in two saltgrass ecotypes. 857 63

Glycinebetaine is one of the compatible solutes that accumulate in the chloroplasts of contain halotolerant plants when these plants are exposed to salt or cold stress. The codA gene for choline oxidase, the enzyme that converts choline into glycinebetaine, has previously been cloned from a soil bacterium, Arthrobacter globiformis. Transformation of Arabidopsis thaliana with the cloned codA gene under the control of the 35S promoter of cauliflower mosaic virus enabled the plant to accumulate glycinebetaine and enhanced its tolerance to salt and cold stress. At 300 mM NaCl, considerable proportions of seeds of transformed plants germinated well, whereas seeds of wild-type plants failed to germinate. At 100 mM NaCl, transformed plants grew well whereas wild-type plants did not do so. The transformed plants tolerated 200 mM NaCl, which was lethal to wild-type plants. After plants had been incubated with 400 mM NaCl for two days, the photosystem II activity of wild-type plants had almost completely disappeared, whereas that of transformed plants remained at more than 50% of the original level. When exposed to a low temperature in the light, leaves of wild-type plants exhibited symptoms of chlorosis, whereas those of transformed plants did not. These observations demonstrate that the genetic modification of Arabidopsis thaliana that allowed it to accumulate glycinebetaine enhanced its ability to tolerate salt and cold stress.
 ...
PMID:Transformation of Arabidopsis thaliana with the codA gene for choline oxidase; accumulation of glycinebetaine and enhanced tolerance to salt and cold stress. 926 56

Seedlings of four deciduous tree species maple (Acer pseudoplatanus), beech (Fagus sylvatica), horse chestnut (Aesculus hippocastanum) and lime (Tilia cordata) were exposed to de-icing salt (NaCl) either through the soil or applied to the above ground plant parts. A soil solution of 1.65 g l-1 NaCl was maintained from the start of the experiment in January 1999 until termination in June 1999. The main effects caused by salt treatment through the soil were a reduction in photosynthesis of up to 50% and the development of leaf chlorosis or necrosis covering up to 50% of the total leaf area for the most sensitive species (lime and beech); maple and horse chestnut were relatively tolerant. There was no significant correlation between Cl or Na concentration in leaves and the relative sensitivity of the species. Saturated salt solution was applied to bark, buds or leaf scars on two occasions three weeks apart during the winter season. This affected the timing of bud break with delays of up to eight days compared with the controls. In the most sensitive species the above ground salt treatments partly prevented bud break (beech) or reduced photosynthesis (lime). Uptake through the bark was most important for the development of stress effects, compared with uptake through the other above ground plant parts.
 ...
PMID:Differences in salt sensitivity of four deciduous tree species to soil or airborne salt. 1190 69

Medicago sativa var. Gabes is a perennial glycophyte that develops new shoots even in high salinity (150 mM NaCl). In the upper exporting leaves, K(+) is high and Na(+) is low by comparison with the lower leaves, where Na(+) accumulation induces chlorosis after 4 weeks of NaCl treatment. By secondary ion mass spectroscopy, a low Na(+)/K(+) ratio was detected in the phloem complex of blade veins in these lower leaves. By transmission electron microscopy, the ultrastructural features were observed in the phloem complex. In the upper leaves of both control and NaCl-treated plants, companion cells in minor veins were found to be transfer cells. These cells may well be involved in the intravenous recycling of ions and in Na(+) flowing out of exporting leaves. Under the effect of NaCl, companion cells in the main veins develop transfer cell features, which may favor the rate of assimilate transport from exporting leaves toward meristems, allowing the positive balance necessary for the survival in salt conditions. These features no longer assist the lower leaves when transfer cells are necrotized in both minor and main veins of NaCl-treated plants. As transfer cells are the only degenerating phloem constituent, our observations emphasize their role in controlling nutrient (in particular, Na(+)) fluxes associated with the stress response.
 ...
PMID:Structural changes induced by NaCl in companion and transfer cells of Medicago sativa blades. 1266 82

This article reports on a study whose aim was to evaluate the impact of snow removal salts on urban soil properties and the health of roadside trees. The evaluation was done by chemical analyses of soil samples and plant matter combined with toxicity testing, performed with a Protoxkit F, a protozoan microbiotest. Samples were collected at 45 locations on three main roads in the town of Opole (Poland). The roads differed in the snow removal technology and amount of chemical substances (mostly NaCl) used on them during the winter. The study showed that when soil was exposed to a high level of NaCl, it tended to be more alkaline and also exhibited increased content of Na(+) and Cl(-). The toxic effects of the soil extract on protozoa appeared at 26.0 mg Na(+)/100 g soil dry mass (s.d.m.) and 12.0 mg Cl(-)/100 g s.d.m., whereas salt injury symptoms (chlorosis and necrosis of the edge of leaf blades) appeared at 13.2 mg Na(+)/100 g s.d.m. and 3.9 mg Cl(-)/100 g s.d.m., becoming more severe at 26.0 mg Na(+)/100 g s.d.m. and 12.0 mg Cl(-)/100 g s.d.m. because of extensive necrosis and defoliation. The lysimetric experiment, which was used to test soil samples collected from the city park area, indicated that salt plays a significant role in the pollution of soil in urban areas, with the least toxic salt being CaCl(2).
 ...
PMID:Effect of deicing salts on urban soils and health status of roadside trees in the Opole region. 1526 99

T-DNA disruption mutations in the AtHKT1 gene have previously been shown to suppress the salt sensitivity of the sos3 mutant. However, both sos3 and athkt1 single mutants show sodium (Na+) hypersensitivity. In the present study we further analyzed the underlying mechanisms for these non-additive and counteracting Na+ sensitivities by characterizing athkt1-1 sos3 and athkt1-2 sos3 double mutant plants. Unexpectedly, mature double mutant plants grown in soil clearly showed an increased Na+ hypersensitivity compared with wild-type plants when plants were subjected to salinity stress. The salt sensitive phenotype of athkt1 sos3 double mutant plants was similar to that of athkt1 plants, which showed chlorosis in leaves and stems. The Na+ content in xylem sap samples of soil-grown athkt1 sos3 double and athkt1 single mutant plants showed dramatic Na+ overaccumulation in response to salinity stress. Salinity stress analyses using basic minimal nutrient medium and Murashige-Skoog (MS) medium revealed that athkt1 sos3 double mutant plants show a more athkt1 single mutant-like phenotype in the presence of 3 mM external Ca2+, but show a more sos3 single mutant-like phenotype in the presence of 1 mM external Ca2+. Taken together multiple analyses demonstrate that the external Ca2+ concentration strongly impacts the Na+ stress response of athkt1 sos3 double mutants. Furthermore, the presented findings show that SOS3 and AtHKT1 are physiologically distinct major determinants of salinity resistance such that sos3 more strongly causes Na+ overaccumulation in roots, whereas athkt1 causes an increase in Na+ levels in the xylem sap and shoots and a concomitant Na+ reduction in roots.
 ...
PMID:Calcium regulation of sodium hypersensitivities of sos3 and athkt1 mutants. 1654 Apr 84

The effects of Cd(2+) and NaCl, applied together or separately, on growth and uptake of Cd(2+) were determined for the halophyte Sesuvium portulacastrum L. Seedlings were cultivated in the presence of 50 or 100 micromol L(-1) Cd(2+) alone or combined with 100 or 400 mmol L(-1) NaCl. Data showed that alone, Cd(2+) induced chlorosis, necrosis, and inhibited growth. Addition of NaCl to Cd(2+)-containing medium restored growth and alleviated the toxicity, however. NaCl also enhanced the amounts of Cd(2+) accumulated in the shoots. All Cd(2+) treatment reduced K(+) and Ca(2+) uptake and transport to the shoots. Accumulation of Na(+) in the shoots was not affected by Cd(2+), however. Thus S. portulacastrum maintained its halophytic characteristics in the presence of Cd(2+). We suggest this halophyte could be used for phytoextraction of Cd(2+) from salt-contaminated sites.
 ...
PMID:Cd-induced growth reduction in the halophyte Sesuvium portulacastrum is significantly improved by NaCl. 1702 35

Transgenic Arabidopsis plants overexpressing the wheat vacuolar Na(+)/H(+) antiporter TNHX1 and H(+)-PPase TVP1 are much more resistant to high concentrations of NaCl and to water deprivation than the wild-type strains. These transgenic plants grow well in the presence of 200 mM NaCl and also under a water-deprivation regime, while wild-type plants exhibit chlorosis and growth inhibition. Leaf area decreased much more in wild-type than in transgenic plants subjected to salt or drought stress. The leaf water potential was less negative for wild-type than for transgenic plants. This could be due to an enhanced osmotic adjustment in the transgenic plants. Moreover, these transgenic plants accumulate more Na(+) and K(+) in their leaf tissue than the wild-type plants. The toxic effect of Na(+) accumulation in the cytosol is reduced by its sequestration into the vacuole. The rate of water loss under drought or salt stress was higher in wild-type than transgenic plants. Increased vacuolar solute accumulation and water retention could confer the phenotype of salt and drought tolerance of the transgenic plants. Overexpression of the isolated genes from wheat in Arabidopsis thaliana plants is worthwhile to elucidate the contribution of these proteins to the tolerance mechanism to salt and drought. Adopting a similar strategy could be one way of developing transgenic staple crops with improved tolerance to these important abiotic stresses.
 ...
PMID:Overexpression of wheat Na+/H+ antiporter TNHX1 and H+-pyrophosphatase TVP1 improve salt- and drought-stress tolerance in Arabidopsis thaliana plants. 1722 60


1 2 3 4 5 Next >>