Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00080 (Leaf)
 21,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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PMID:Development of plants from leaf discs of variegated Coleus and its relation to patterns of leaf chlorosis. 66 30

A genetic transformation system has been developed for three Mycosphaerella pathogens of banana and plantain (Musa spp.). Mycosphaerella fijiensis and Mycosphaerella musicola, the causal agents of black and yellow Sigatoka, respectively, and Mycosphaerella eumusae, which causes Septoria leaf spot of banana, were transformed with a construct carrying a synthetic gene encoding green fluorescent protein (GFP). Most single-spored transformants that expressed GFP constitutively were mitotically stable in the absence of selection for hygromycin B resistance. Transformants of all three species were pathogenic on the susceptible banana cultivar Grand Nain, and growth in planta was comparable to wild-type strains. GFP expression by transformants allowed us to observe extensive fungal growth within leaf tissue that eventually turned necrotic, at which point the fungi grew saprophytically on the dead tissue. Leaf chlorosis and necrosis were often observed in advance of saprophytic growth of the mycelium on necrotic tissue, which supports previous reports suggesting secretion of a phytotoxin.
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PMID:Development of a transformation system for Mycosphaerella pathogens of banana: a tool for the study of host/pathogen interactions. 1116 88

Brassica napus L. (oilseed rape) was grown from seeds on a reconstituted soil contaminated with cadmium (100 mg Cd kg-1 dry soil), resulting in a marked chlorosis of the leaves which was investigated using a combination of biochemical, biophysical and physiological methods. Spectroscopic and chromatographic analyses of the photosynthetic pigments indicated that chlorosis was not due to a direct interaction of Cd with the chlorophyll biosynthesis pathway. In addition, mineral deficiency and oxidative stress were apparently not involved in the pigment loss. Leaf chlorosis was attributable to a marked decrease in the chloroplast density caused by a reduction in the number of chloroplasts per cell and a change in cell size, suggesting that Cd interfered with chloroplast replication and cell division. Relatively little Cd was found in the chloroplasts and the properties of the photosynthetic apparatus (electron transport, protein composition, chlorophyll antenna size, chloroplast ultrastructure) were not affected appreciably in plants grown on Cd-polluted soil. Depth profiling of photosynthetic pigments by phase-resolved photoacoustic spectroscopy revealed that the Cd-induced decrease in pigment content was very pronounced at the leaf surface (stomatal guard cells) compared to the leaf interior (mesophyll). This observation was consistent with light transmission and fluorescence microscopy analyses, which revealed that stomata density in the epidermis was noticeably reduced in Cd-exposed leaves. Concomitantly, the stomatal conductance estimated from gas-exchange measurements was strongly reduced with Cd. When plants were grown in a high-CO2 atmosphere (4,000 microliters CO2 l-1), the inhibitory effect of Cd on growth was not cancelled, suggesting that the reduced availability of CO2 at the chloroplast level associated with the low stomatal conductance was not the main component of Cd toxicity in oilseed rape.
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PMID:Leaf chlorosis in oilseed rape plants (Brassica napus) grown on cadmium-polluted soil: causes and consequences for photosynthesis and growth. 1134 43

The role of blue light in plant growth and development was investigated in soybean (Glycine max [L.] Merr. cv Williams) and sorghum (Sorghum bicolor [L.] Moench. cv Rio) grown under equal photosynthetic photon fluxes (approximately 500 micromoles per square meter per second) from broad spectrum daylight fluorescent or blue-deficient, narrow-band (589 nanometers) low pressure sodium (LPS) lamps. Between 14 and 18 days after sowing, it was possible to relate adaptations in photosynthesis and leaf growth to dry matter accumulation. Soybean development under LPS light was similar in several respects to that of shaded plants, consistent with an important role for blue light photoreceptors in regulation of growth response to irradiance. Thus, soybeans from LPS conditions partitioned relatively more growth to leaves and maintained higher average leaf area ratios (mean LAR) that compensated lower net assimilation rates (mean NAR). Relative growth rates were therefore comparable to plants from daylight fluorescent lamps. Reductions in mean NAR were matched by lower rates of net photosynthesis (A) on an area basis in the major photosynthetic source (first trifoliolate) leaf. Lower A in soybean resulted from reduced leaf dry matter per unit leaf area, but lower A under LPS conditions in sorghum correlated with leaf chlorosis and reduced total nitrogen (not observed in soybean). In spite of a lower A, mean NAR was larger in sorghum from LPS conditions, resulting in significantly greater relative growth rates (mean LAR was approximately equal for both light conditions). Leaf starch accumulation rate was higher for both species and starch content at the end of the dark period was elevated two- and three-fold for sorghum and soybean, respectively, under LPS conditions. Possible relations between starch accumulation, leaf export, and plant growth in response to spectral quality were considered.
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PMID:Photomorphogenesis and photoassimilation in soybean and sorghum grown under broad spectrum or blue-deficient light sources. 1153 84

Humic acid (HA) is a relatively stable product of organic matter decomposition and thus accumulates in environmental systems. Humic acid might benefit plant growth by chelating unavailable nutrients and buffering pH. We examined the effect of HA on growth and micronutrient uptake in wheat (Triticum aestivum L.) grown hydroponically. Four root-zone treatments were compared: (i) 25 micromoles synthetic chelate N-(4-hydroxyethyl)ethylenediaminetriacetic acid (C10H18N2O7) (HEDTA at 0.25 mM C); (ii) 25 micromoles synthetic chelate with 4-morpholineethanesulfonic acid (C6H13N4S) (MES at 5 mM C) pH buffer; (iii) HA at 1 mM C without synthetic chelate or buffer; and (iv) no synthetic chelate or buffer. Ample inorganic Fe (35 micromoles Fe3+) was supplied in all treatments. There was no statistically significant difference in total biomass or seed yield among treatments, but HA was effective at ameliorating the leaf interveinal chlorosis that occurred during early growth of the nonchelated treatment. Leaf-tissue Cu and Zn concentrations were lower in the HEDTA treatment relative to no chelate (NC), indicating HEDTA strongly complexed these nutrients, thus reducing their free ion activities and hence, bioavailability. Humic acid did not complex Zn as strongly and chemical equilibrium modeling supported these results. Titration tests indicated that HA was not an effective pH buffer at 1 mM C, and higher levels resulted in HA-Ca and HA-Mg flocculation in the nutrient solution.
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PMID:Beneficial effects of humic acid on micronutrient availability to wheat. 1188 4

This study was designed to categorize the resistance to the Russian wheat aphid, Diuraphis noxia (Mordvilko), resistant hard red winter wheat, Halt, as compared with susceptible wheat, TAM 107, at four different growth stages. Antixenosis was expressed in Halt at growth stage Zadoks 30. Antibiosis in Halt affected fecundity, number of aphids produced per reproductive day, maximum number of nymphs produced in one day, and intrinsic rate of increase. Fecundity was lower on Halt than TAM 107, and more nymphs were produced on both varieties at growth stage 20 than 10 and 40. Fewer nymphs were produced per reproductive day and on maximum production days by aphids reared on Halt than by those reared on TAM 107. The intrinsic rate of increase of Russian wheat aphids reared on Halt was lower than aphids reared on TAM 107. Differences in plant height and plant dry weight did not occur. Chlorosis ratings showed greater damage at the earlier stages in Halt and TAM 107 and significantly more damage in TAM 107 than Halt at growth stages 10, 20, and 30. Leaf rolling occurred on infested plants of TAM 107 at growth stages 10, 20, and 30, but not growth stage 40. Halt plants did not exhibit leaf rolling. The presence of a significant level of tolerance could make Halt compatible with other integrated pest management programs. However, care should be taken with cultivars containing evidence of antixenosis or antibiosis that could cause selective pressure on the Russian wheat aphid, potentially causing biotypes to be produced.
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PMID:Categories of resistance at different growth stages in halt, a winter wheat resistant to the Russian wheat aphid (Homoptera: Aphididae). 1265 Mar 65

Brassica napus (L.) was grown from seeds on a reconstituted soil contaminated with 100 mg Cd kg(-1). Compared with roots and stems, leaves accumulated high amounts of Cd. Although the Cd concentration in the leaves remained high throughout plant growth and no appreciable change was noticed in the total, extractable or soluble Cd in the soil adhering to the roots, the symptoms of Cd toxicity (leaf chlorosis, growth retardation) decreased with time. Cd induced a noticeable accumulation of phytochelatins in young plants (aged 22 days), which decreased in parallel to the disappearance of the symptoms of Cd intoxication. The subcellular distribution of Cd in leaves of Cd-acclimated plants was determined using biochemical, microscopic and metal-imaging techniques. Leaf fractionation by differential centrifugations showed that Cd was present predominantly in the 'soluble' fraction corresponding to the vacuoles and the cytoplasm. Transmission electron microscopic analyses revealed that those cell compartments contained electron-dense granules associated with needle-like structures. Cd, and also high amounts of sulfur, was detected in those structures by electron-spectroscopic imaging. This technique also showed Cd binding to cell walls by a mechanism that does not involve sulfur atoms. In contrast, very little Cd was found in chloroplasts, and this is consistent with the preservation of photosynthesis in plants grown on Cd-polluted soil. The microanalytical results presented here confirm that long-term growth of B. napus on Cd-contaminated soil is accompanied by preferential storage of Cd in the vacuoles and the cell walls. This phenomenon diverted Cd ions from metabolically active compartments (cytosol, chloroplasts, mitochondria), resulting in a reduction of Cd toxicity in the leaves.
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PMID:Cadmium distribution and microlocalization in oilseed rape (Brassica napus) after long-term growth on cadmium-contaminated soil. 1268 61

The genus Brevipalpus includes most of the economically important species of Tenuipalpidae. Many Brevipalpus species reproduce by theletokous parthenogenesis while other species reproduce by male fertilization of female eggs. Previous researchers have determined that Brevipalpus californicus (Banks), B. obovatus Donnadieu, and B. phoenicis (Geijskes) females were haploid with two chromosomes. The life cycle and developmental times for these three species are reviewed. Longevity of each Brevipalpus species is two to three times greater than corresponding longevities of various tetranychid mites. Brevipalpus mites inject toxic saliva into fruits, leaves, stems, twigs, and bud tissues of numerous plants including citrus. Feeding injury symptoms on selected plants include: chlorosis, blistering, bronzing, or necrotic areas on leaves by one or more Brevipalpus mites. Premature leaf drop occurred on 'Robinson' tangerine leaves in Florida (USA). Leaf drop was observed in several sweet orange and grapefruit orchards in Texas (USA) that were heavily infested with Brevipalpus mites feeding on the twigs, leaves, and fruit. Initial circular chlorotic areas appear on both sweet orange and grapefruit varieties in association with developing populations of Brevipalpus mites in Texas. These feeding sites become progressively necrotic, darker in color, and eventually develop into irregular scab-like lesions on affected fruit. Russeting and cracking of the fruits of other plant hosts are reported. Stunting of leaves and the development of Brevipalpus galls on terminal buds were recorded on sour orange, Citrus aurantium L., seedlings heavily infested with B. californicus in an insectary. The most significant threat posed by these mites is as vectors of a potentially invasive viral disease called citrus leprosis.
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PMID:Brevipalpus californicus, B. obovatus, B. phoenicis, and B. lewisi (Acari: Tenuipalpidae): a review of their biology, feeding injury and economic importance. 1475 11

Leaf nutrition and photosynthetic performance of sugar maple (Acer saccharum Marsh.) were compared between two sugar maple stands in northwestern Vermont with contrasting health conditions as indicated by annual basal area growth, degree of crown dieback, and foliar appearance. Observations made during the diurnal cycle of both stands showed no apparent leaf water stress. In both stands, leaves had similar concentrations of major non-structural carbohydrates (starch and sucrose). Over two consecutive growing seasons (1991 and 1992), we consistently observed lower leaf Ca and Mg concentrations in the declining stand than in the healthy stand. Compared with the healthy stand, lower leaf chlorophyll concentrations and apparent leaf chlorosis were observed in the declining stand, and some trees had very low foliar Ca and Mg concentrations (0.31 +/- 0.03% and 0.09 +/- 0.01%, respectively). Trees in the declining stand had lower light-saturated net photosynthetic rates on a dry mass basis at both ambient CO(2) (P(n,amb)) and saturating CO(2) (P(n,sat)) than trees in the healthy stand. There were significant linear correlations between P(n,amb) and leaf mass per unit area (LMA) and between P(n,sat) per unit leaf area and LMA. There were also linear correlations between both P(n,amb) and P(n,sat) and leaf N when expressed on an area basis in both stands, indicating that variation in LMA may have been largely responsible for the observed photosynthesis-nitrogen relationship. The values of P(n,amb) and P(n,sat) were not significantly correlated with leaf N on a mass basis but were weakly correlated with leaf Ca and Mg on a mass basis. We conclude that low leaf Ca or Mg concentrations may limit leaf CO(2) assimilation and tree carbohydrate status in the declining stand.
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PMID:Leaf nutrition and photosynthetic performance of sugar maple (Acer saccharum) in stands with contrasting health conditions. 1475 71

The purpose of this study was to determine whether or not young hybrid poplar (Populus deltoides x Populus nigra) could transport landfill biogas internally from the root zone to the atmosphere, thereby acting as conduits for landfill gas release. Fluxes of methane (CH4) and nitrous oxide (N2O) from the seedlings to the atmosphere were measured under controlled conditions using dynamic flux chambers and a tunable diode laser trace gas analyser (TDLTGA). Nitrous oxide was emitted from the seedlings, but only when extremely high soil N2O concentrations were applied to the root zone. In contrast, no detectable emissions of CH4 were measured in a similar experimental trial. Visible plant morphological responses, characteristic of flood-tolerant trees attempting to cope with the negative effects of soil hypoxia, were observed during the CH4 experiments. Leaf chlorosis, leaf abscission and adventitious roots were all visible plant responses. In addition, seedling survival was observed to be highest in the biogas 'hot spot' areas of a local municipal solid waste landfill involved in this study. Based on the available literature, these observations suggest that CH4 can be transported internally by Populus deltoides x Populus nigra seedlings in trace amounts, although future research is required to fully test this hypothesis.
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PMID:Laboratory-scale measurements of N2O and CH4 emissions from hybrid poplars (Populus deltoides x Populus nigra). 1566 48


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