Subcellular and tissue Mn compartmentation in bean leaves under Mn toxicity stress

1999 ◽  
Vol 26 (8) ◽  
pp. 811 ◽  
Author(s):  
Alonso González ◽  
Jonathan P. Lynch
Keyword(s):  
Common Bean ◽  
Developmental Stages ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
High Accumulation ◽  
Mn Toxicity ◽  
Mature Leaves ◽  
Mn Content ◽  
Mn Concentration

Non-aqueous fractionation was used to characterize subcellular and tissue Mn compartmentation of mature and immature leaves of two common bean (Phaseolus vulgaris L.) cultivars contrasting in their response to Mn toxicity. Excess Mn decreases leaf CO2 assimilation through a reduction of chlorophyll content in immature leaves with no effect detected on mature leaves. We hypothesized that differential accumulation of Mn in chloroplasts occurs at different leaf developmental stages. Chloroplasts of immature leaves accumulated at least three times as much Mn as those of mature leaves at equivalent total foliar Mn. Chlorosis was positively correlated with Mn concentration in chloroplasts from high-Mn plants (r2 = 0.96; P = 0.003) but was not correlated with Mn in unfractionated tissue (r2 = 0.026; P = 0.793) nor with Mn in the epidermis-enriched fraction (r2 = 0.33; P = 0.314). Both cultivars showed high accumulation of Mn in the vacuoles as determined by the co-localization of α-mannosidase and Mn content on a continuous density gradient. Cultivars differed significantly in Mn concentration in an epidermis-enriched fraction, with the tolerant cultivar Calima accumulating more Mn in this fraction than the sensitive cultivar ZPV-292. In both cultivars, Mn was accumulated up to 2400 µg g–1 dry weight in crystal-type structures whereas the unfractionated leaf tissue contained about 500 µg g–1 dry weight. The results demonstrate that Mn compartmentation occurs at both the tissue and the organelle level and that Mn accumulation in the epidermis-enriched fraction could contribute to Mn tolerance in common bean. The role of Mn accumulation in structures resembling oxalate crystals is discussed.

Carbon Dioxide Assimilation by Pineapple Plants, Ananas comosus (L.) Merr. I. Effects of Daily Irradiance

1980 ◽  
Vol 7 (4) ◽  
pp. 363 ◽  
Author(s):  
PJM Sale ◽  
TF Neales
Keyword(s):  
Leaf Area ◽  
Leaf Tissue ◽  
Extended Period ◽  
Titratable Acidity ◽  
Dry Weight ◽  
Co2 Assimilation ◽  
Co2 Exchange ◽  
Ananas Comosus ◽  
Molar Ratio ◽  
Weight Changes

Net carbon exchange over 24-h cycles was measured in well watered pineapple plants, using a 'minicrop' in field assimilation chambers and single leaves in a growth cabinet. Whole plants under natural light and a standard 30°C day/15°C night regime showed crassulacean acid metabolism, nearly all assimilation occurring in the dark period, with a net efflux of CO2 in the day. Assimilation, as measured by both CO2 exchange and changes in titratable acidity in the leaf tissue, was markedly dependent on the total photosynthetically active radiation incident in the previous photoperiod. The molar ratio of the maximum acidity change to maximum net nocturnal CO2 influx was 1.8 : 1. The rate of deacidification depended on the irradiance in the current photoperiod. Efflux in the photoperiod was largely independent of irradiance, but was greater at very low irradiances. Maximum rates of CO2 assimilation in the minicrop were about 15 ng cm-2 (leaf area) s-1 in the dark at the standard temperature regime, and 22 ng-2 s-1 when photoperiod assimilation was induced by a 20°C day/30°C night regime. Similar rates were recorded in the single-leaf experiments, and are higher than those previously found for pineapple. Over a 24-h period, mean rates of about 6 ng cm-2 (leaf area) s-1 were recorded, in good agreement with measured dry weight changes over an extended period. These data help to explain earlier discrepancies in the literature between measured rates of CO2 assimilation and of crop growth rates in pineapples.

scholarly journals The role of JrPPOs in the browning of walnut explants

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shugang Zhao ◽  
Hongxia Wang ◽  
Kai Liu ◽  
Linqing Li ◽  
Jinbing Yang ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Production Efficiency ◽  
Phenolic Content ◽  
Leaf Tissue ◽  
Limiting Factor ◽  
Mature Leaves ◽  
Survival Percentage ◽  
Highly Active ◽  
Young Leaves

Abstract Background Tissue culture is an effective method for the rapid breeding of seedlings and improving production efficiency, but explant browning is a key limiting factor of walnut tissue culture. Specifically, the polymerization of PPO-derived quinones that cause explant browning of walnut is not well understood. This study investigated explants of ‘Zanmei’ walnut shoot apices cultured in agar (A) or vermiculite (V) media, and the survival percentage, changes in phenolic content, POD and PPO activity, and JrPPO expression in explants were studied to determine the role of PPO in the browning of walnut explants. Results The results showed that the V media greatly reduced the death rate of explants, and 89.9 and 38.7% of the explants cultured in V media and A media survived, respectively. Compared with that of explants at 0 h, the PPO of explants cultured in A was highly active throughout the culture, but activity in those cultured in V remained low. The phenolic level of explants cultured in A increased significantly at 72 h but subsequently declined, and the content in the explants cultured in V increased to a high level only at 144 h. The POD in explants cultured in V showed high activity that did not cause browning. Gene expression assays showed that the expression of JrPPO1 was downregulated in explants cultured in both A and V. However, the expression of JrPPO2 was upregulated in explants cultured in A throughout the culture and upregulated in V at 144 h. JrPPO expression analyses in different tissues showed that JrPPO1 was highly expressed in stems, young leaves, mature leaves, catkins, pistils, and hulls, and JrPPO2 was highly expressed in mature leaves and pistils. Moreover, browning assays showed that both explants in A and leaf tissue exhibited high JrPPO2 activity. Conclusion The rapid increase in phenolic content caused the browning and death of explants. V media delayed the rapid accumulation of phenolic compounds in walnut explants in the short term, which significantly decreased explants mortality. The results suggest that JrPPO2 plays a key role in the oxidation of phenols in explants after branch injury.

INFLUENCE OF CLIPPING HEIGHT ON THE NEUTRAL CARBOHYDRATE LEVELS OF ROOT EXUDATES OF ALFALFA PLANTS GROWN UNDER GNOTOBIOTIC CONDITIONS

1972 ◽  
Vol 52 (4) ◽  
pp. 643-649 ◽  
Author(s):  
R. A. HAMLEN ◽  
F. L. LUKEZIC ◽  
J. R. BLOOM
Keyword(s):  
Root Exudates ◽  
Dry Weight ◽  
Root Tissue ◽  
Minor Components ◽  
Flower Buds ◽  
Total Sugars ◽  
Spectral Techniques ◽  
Mass Spectral ◽  
Mature Leaves ◽  
Carbohydrate Levels

Influence of clipping height on neutral carbohydrate levels in root exudates of alfalfa grown gnotobiotically was investigated by gas-chromatographic and mass-spectral techniques. Exudates were obtained from plants that were lightly clipped (removal of flower buds), intermediately clipped (15 cm), and severely clipped (removal of all but four mature leaves). Glucose, inositol, sucrose, and four unidentified (U) components were detected. Fluctuations in the level of sugars were observed in exudates from two sampling periods. Glucose and U1 were most concentrated under light clipping. Levels of inositol and sucrose were maximum under intermediate clipping. Amounts of U3 were greatest from severely clipped plants, whereas levels of U5 remained constant at all cuttings. Concentration of U4 was lowest under severe clipping. U2, present in exudates from seedling plants, was not detected. Quantities of sugars released per gram of dry weight of root tissue were greater under severe clipping. U1 was the major component, with glucose, inositol, and sucrose minor components of the total sugars.

A Hyperspectral Library of Foliar Diseases of Wheat

2021 ◽  
Author(s):  
David Bohnenkamp ◽  
Jan Behmann ◽  
Stefan Paulus ◽  
Ulrike Steiner ◽  
Anne-Katrin Mahlein
Keyword(s):  
Developmental Stages ◽  
Leaf Tissue ◽  
Plant Diseases ◽  
Identification System ◽  
Spectral Library ◽  
Foliar Diseases ◽  
Robust Detection ◽  
Analysis Methods ◽  
Detection And Identification ◽  
Biotrophic Fungi

This work established a hyperspectral library of important foliar diseases of wheat in time series to detect spectral changes from infection to symptom appearance induced by different pathogens. The data was generated under controlled conditions at the leaf-scale. The transition from healthy to diseased leaf tissue was assessed, spectral shifts were identified and used in combination with histological investigations to define developmental stages in pathogenesis for each disease. The spectral signatures of each plant disease that are indicative of a certain developmental stage during pathogenesis - defined as turning points - were combined into a spectral library. Different machine learning analysis methods were applied and compared to test the potential of this library for the detection and quantification of foliar diseases in hyperspectral images. All evaluated classifiers provided a high accuracy for the detection and identification for both the biotrophic fungi and the necrotrophic fungi of up to 99%. The potential of applying spectral analysis methods, in combination with a spectral library for the detection and identification of plant diseases is demonstrated. Further evaluation and development of these algorithms should contribute to a robust detection and identification system for plant diseases at different developmental stages and the promotion and development of site-specific management techniques of plant diseases under field conditions.

scholarly journals Foliar phosphorus supply and CO2 assimilation in common bean (Phaseolus vulgaris L.) under water deficit

2006 ◽  
Vol 18 (3) ◽  
pp. 407-411 ◽  
Author(s):  
Mauro G. dos Santos ◽  
Rafael V. Ribeiro ◽  
Marcelo G. Teixeira ◽  
Ricardo F. de Oliveira ◽  
Carlos Pimentel
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Water Deficit ◽  
Co2 Assimilation ◽  
Assimilation Rate ◽  
Phaseolus Vulgaris L ◽  
Co2 Assimilation Rate ◽  
Net Co2 Assimilation ◽  
Foliar Phosphorus ◽  
Regulation Of Photosynthesis

Two common bean cultivars were grown in pots under greenhouse conditions. Plants were submitted to a foliar Pi spray two days before suspending irrigation, what enhanced net CO2 assimilation rate of Ouro Negro cultivar but did not change significantly the photosynthesis of Carioca cultivar under both water deficit and rehydration periods. The results revealed that a foliar Pi spray induced an up-regulation of photosynthesis in common bean under mild water deficit, with this effect being genotype-dependent.

scholarly journals Responses of Tomato to Potassium Rates in a Calcareous Soil

HortScience ◽  
2017 ◽  
Vol 52 (5) ◽  
pp. 764-769 ◽  
Author(s):  
Qiang Zhu ◽  
Monica Ozores-Hampton ◽  
Yuncong Li ◽  
Kelly Morgan ◽  
Guodong Liu ◽  
...  
Keyword(s):  
Calcareous Soil ◽  
Plant Biomass ◽  
Winter Season ◽  
Calcareous Soils ◽  
Leaf Tissue ◽  
Dry Weight ◽  
The United States ◽  
Ammonium Bicarbonate ◽  
Soluble Solids ◽  
Postharvest Quality

Florida produces the most vegetables in the United States during the winter season with favorable weather conditions. However, vegetables grown on calcareous soils in Florida have no potassium (K) fertilizer recommendation. The objective of this study was to evaluate the effects of K rates on leaf tissue K concentration (LTKC), plant biomass, fruit yield, and postharvest quality of tomatoes (Solanum lycopersicum L.) grown on a calcareous soil. The experiment was conducted during the winter seasons of 2014 and 2015 in Homestead, FL. Potassium fertilizers were applied at rates of 0, 56, 93, 149, 186, and 223 kg·ha−1 of K and divided into preplant dry fertilizer and fertigation during the season. No deficiency of LTKC was found at 30 days after transplanting (DAT) in both years. Potassium rates lower than 149 kg·ha−1 resulted in deficient LTKC at 95 DAT in 2014. No significant responses to K rates were observed in plant (leaf, stem, and root combined) dry weight biomass at all the sampling dates in both years. However, at 95 DAT, fruit dry weight biomass increased with increasing K rates to 130 and 147 kg·ha−1, reaching a plateau thereafter indicated by the linear-plateau models in 2014 and 2015, respectively. Predicted from quadratic and linear-plateau models, K rates of 173 and 178 kg·ha−1 were considered as the optimum rates for total season marketable yields in 2014 and 2015, respectively. Postharvest qualities, including fruit firmness, pH, and total soluble solids (TSS) content, were not significantly affected by K rates in both years. Overall, K rate of 178 kg·ha−1 was sufficient to grow tomato during the winter season in calcareous soils with 78 to 82 mg·kg−1 of ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extracted K in Florida.

Adaptation to Water Stress of the Leaf Water Relations of Four Tropical Forage Species

1980 ◽  
Vol 7 (2) ◽  
pp. 207 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow ◽  
MJ Fisher ◽  
E Schulze
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Water Relations ◽  
Bound Water ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Panicum Maximum ◽  
Soil Drying ◽  
Buffel Grass ◽  
Heteropogon Contortus

Three tropical grasses, green panic (Panicum maximum var, trichoglume), spear grass (Heteropogon contortus) and buffel grass (Cenchrus ciliaris) and the tropical legume siratro (Macroptilium atropurpureum), were grown in plots in a semi-arid field environment. The water relations characteristics of leaves from plants subjected to a soil drying cycle were compared with those of unstressed leaves from plants in irrigated plots. Minimum water potentials attained in the stressed leaves were c. -44, - 38, - 33 and - 13 bar for the four species, respectively. The grass leaves adjusted osmotically to water stress, apparently through accumulation of solutes, so that there was a decrease in osmotic potential at full turgor (Ψπ100) of 5.5, 3.9 and 7.1 bar, and in water potential at zero turgor (Ψ0) of 8.6, 6.5 and 8.6 bar for green panic, spear grass and buffel respectively. Water stress appeared to increase slightly the proportion of bound water (B) and the bulk modulus of elasticity (ε) of the grass leaves, but it did not alter the relative water content at zero turgor (RWC0) or the ratio of turgid water content to dry weight of the tissue. The Ψπ100 and Ψ0 of stressed siratro leaves decreased by 2.5-4 bar and 3-5 bar respectively when subjected to soil drying cycles. These changes could be explained by the marked decrease in the ratio of turgid water content to dry weight of the leaf tissue rather than by accumulation of solutes. The values of RWC0 and ε for siratro leaves were not altered by stress but, in contrast to the grasses, B was apparently decreased although the data exhibited high variability. Adjustments in Ψπ100 and Ψ0 of stressed leaves of buffel grass and siratro were largely lost within 10 days of rewatering.

scholarly journals The direct and indirect effects of nitrogen shortage on photosynthesis and transpiration in maize and sunflower.

1979 ◽  
Vol 27 (3) ◽  
pp. 227-234
Author(s):  
J. Goudriaan ◽  
H. van Keulen
Keyword(s):  
Indirect Effects ◽  
Leaf Tissue ◽  
Co2 Assimilation ◽  
Direct And Indirect Effects ◽  
Stomatal Behaviour ◽  
Net Co2 Assimilation ◽  
Similar Relation ◽  
Use Efficiency ◽  
Different Levels ◽  
N Status

Experiments with maize and sunflower in sol. culture were carried out to investigate the effect of N shortage in the leaf tissue on stomatal behaviour. In maize a linear relation existed between the rate of net CO2 assimilation and the conductance of water vapour, independently of the N status of the tissue. In sunflower a similar relation existed although the evidence was less conclusive. It was concluded that stomatal behaviour cannot explain differences in water-use efficiency between plants growing at different levels of N. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Evaluation of a screening technique for manganese toxicity in relation to leaf manganese distribution and interaction with silicon.

1981 ◽  
Vol 29 (4) ◽  
pp. 297-304
Author(s):  
C.R. Blatt ◽  
A. van Diest
Keyword(s):  
Manganese Toxicity ◽  
Test Solution ◽  
High Toxicity ◽  
Mn Toxicity ◽  
Screening Technique ◽  
Manganese Tolerance ◽  
Nutrient Culture ◽  
Mn Content ◽  
Leaves And Roots

A screening technique utilizing a flowing nutrient culture was used to evaluate 20 lettuce cultivars differing in the severity of the toxicity symptoms marginal yellowing and necrosis in older leaves. Growth, leaf and root Mn contents and toxicity ratings (1 = no symptoms to 5 = high toxicity) were recorded over six Mn and two Si concentrations. A test solution of 0.5-1.0 mg/l Mn produced consistent toxicity ratings and the ratings for tolerant and sensitive cultivars were similar to ratings for the same cultivars grown under glasshouse conditions. Total Mn content in leaves was not a useful index for Mn sensitivity. Increased Si resulted in a repression of toxicity symptoms and decreased shoot/root Mn ratios in 12 cultivars. ADDITIONAL ABSTRACT: A screening technique was developed to evaluate lettuce cultivars for manganese tolerance in flowing nutrient culture. Considerable variation in the sensitivity of 20 cultivars was observed, as shown by visible symptoms. However there was no correlation between accumulation of Mn in leaves and roots and the degree of Mn tolerance. Increasing silicon in the solution repressed Mn toxicity symptoms, but had variable effects on the Mn content of leaves and roots. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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