scholarly journals INFLORESCENCE SINK DEMAND AND LEAF BLACKENING IN PROTEA NERIIFOLIA.

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 617a-617
Author(s):  
Robyn McConchie ◽  
N.Suzanne Lang
Keyword(s):  
Lipid Peroxidation ◽  
Stomatal Conductance ◽  
Exchange Rates ◽  
Pulse Treatment ◽  
Nonstructural Carbohydrates ◽  
Leaf Respiration ◽  
Respiration Rates ◽  
Carbohydrate Depletion ◽  
Sink Demand ◽  
Over Time

A major postharvest problem of Protea neriifolia is premature leaf blackening. Carbohydrate stress, due to floral sink demand, may lead to cellular disorganization and leaf blackening. Leaf blackening, nonstructural carbohydrates, ethylene, carbon exchange rates, stomatal conductance and lipid peroxidation were measured on leaves of vegetative and floral stems preharvest, and during a 7 day dark postharvest period. Postharvest treatments were: 0 or 0.5% sucrose in the vase solution, 20% sucrose pulse, or floral decapitation. Leaf blackening was significantly reduced in vegetative stems and floral stems in the 20% pulse treatment, in comparison to all other treatments. Ethylene production and lipid peroxidation were not associated with leaf blackening in any treatment and leaf respiration rates declined for all treatments over time. The magnitude and rate of leaf blackening was inversely related to leaf starch concentrations, with greatest carbohydrate depletion occurring within 24 h of harvest (by 75-85%). Leaf starch from the 20% pulse treatment increased by 300%, in contrast to declining starch concentrations in all other treatments. The data suggest that the flowerhead functions as the major sink for carbohydrate depletion leading to subsequent leaf blackening.

scholarly journals Carbohydrate Metabolism and Possible Mechanisms of Leaf Blackening in Protea neriifolia under Dark Postharvest Conditions

1993 ◽  
Vol 118 (3) ◽  
pp. 355-361 ◽  
Author(s):  
Robyn McConchie ◽  
N. Suzanne Lang
Keyword(s):  
Lipid Peroxidation ◽  
Sucrose Concentration ◽  
Concentration Profiles ◽  
Oxidized Glutathione ◽  
Membrane Degradation ◽  
Leaf Respiration ◽  
Initial Decrease ◽  
Carbohydrate Depletion ◽  
Sink Demand ◽  
H 20

During a 7-day dark postharvest period, Protea neriifolia R.Br. leaf blackening was significantly reduced on floral stems treated with a 24-h 20% sucrose pulse compared with continuous holding in a 0.5% sucrose vase solution or removal of the flowerhead. Leaf blackening on vegetative stems was similar to that on the 20% sucrose-pulsed floral stems. Leaf starch and sucrose concentration profiles demonstrated that stems with reduced leaf blackening maintained higher levels of those carbohydrates during the early postharvest period. Conversely, leaf starch and sucrose reserves were quickly depleted in stem treatments that resulted in early blackening symptoms. Starch concentrations in all treatments of stems dropped 70% to 82% within 24 h of harvest, suggesting that leaf blackening may be initiated during shipping. Ethylene production was not associated with leaf blackening in any treatment. Lipid peroxidation did not differ among floral treatments nor did it increase over the postharvest interval. Oxidized glutathione (GSSG) concentration increased only with the 20% pulsed stems and was not related to leaf blackening. After an initial decrease, leaf respiration rate was generally maintained regardless of treatment. Collectively, these data are consistent with the hypothesis that carbohydrate depletion is the initiating factor in leaf blackening and is accelerated by inflorescence sink demand. We suggest that membrane degradation does not necessarily precede leaf blackening.

Short-term exercise training can improve myocardial tolerance to I/R without elevation in heat shock proteins

2001 ◽  
Vol 281 (3) ◽  
pp. H1346-H1352 ◽  
Author(s):  
Karyn L. Hamilton ◽  
Scott K. Powers ◽  
Takao Sugiura ◽  
Sunjoo Kim ◽  
Shannon Lennon ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Ischemia Reperfusion ◽  
Left Ventricular ◽  
Antioxidant Defenses ◽  
Control Group ◽  
Shock Proteins ◽  
Mnsod Activity ◽  
Over Time

We examined the effects of 3 days of exercise in a cold environment on the expression of left ventricular (LV) heat shock proteins (HSPs) and contractile performance during in vivo ischemia-reperfusion (I/R). Sprague-Dawley rats were divided into the following three groups ( n = 12/group): 1) control, 2) exercise (60 min/day) at 4°C (E-Cold), and 3) exercise (60 min/day) at 25°C (E-Warm). Left anterior descending coronary occlusion was maintained for 20 min, followed by 30 min of reperfusion. Compared with the control group, both the E-Cold and E-Warm groups maintained higher ( P < 0.05) LV developed pressure, first derivative of pressure development over time (+dP/d t), and pressure relaxation over time (−dP/d t) throughout I/R. Relative levels of HSP90, HSP72, and HSP40 were higher ( P < 0.05) in E-Warm animals compared with both control and E-Cold. HSP10, HSP60, and HSP73 did not differ between groups. Exercise increased manganese superoxide dismutase (MnSOD) activity in both E-Warm and E-Cold hearts ( P < 0.05). Protection against I/R-induced lipid peroxidation in the LV paralleled the increase in MnSOD activity whereas lower levels of lipid peroxidation were observed in both E-Warm and E-Cold groups compared with control. We conclude that exercise-induced myocardial protection against a moderate duration I/R insult is not dependent on increases in myocardial HSPs. We postulate that exercise-associated cardioprotection may depend, in part, on increases in myocardial antioxidant defenses.

scholarly journals Carbohydrate Depletion and Leaf Blackening in Protea neriljiolia

1991 ◽  
Vol 116 (6) ◽  
pp. 1019-1024 ◽  
Author(s):  
Robyn McConchie ◽  
N. Suzanne Lang ◽  
Ken C. Gross
Keyword(s):  
Sink Strength ◽  
Cut Flower ◽  
Continuous Darkness ◽  
Primary Stress ◽  
Leaf Carbohydrates ◽  
Carbohydrate Depletion ◽  
Sink Demand ◽  
And Storage ◽  
Exogenous Sugar ◽  
Storage Reserves

Leaf blackening on cut flower Protea nerii[olia R. Br. stems was dramatically reduced under a 12-hour photosynthetic light period (120 μmol·m-2·s-1) at 25C for 15 days compared with stems kept in the dark. In the light, addition of 0.5% exogenous sugar to the vase solution resulted in a maximum of 2.5% leaf blackening, while stems with no exogenous sugar had a maximum of 16.5%. Continuous darkness resulted in 94% leaf blackening by day 7, irrespective of sugar treatment. Starch and sucrose concentrations were markedly lower in leaves on dark-held stems than in leaves on stems held in the light; thus, carbohydrate depletion could be the primary stress that initiates leaf blackening. In the light, rates of carbon exchange and assimilate export were similar, indicating that the amount of carbon fixed maybe regulated by sink demand. The pattern of carbon partitioning changed in light-held leaves of the 0% sugar treatment during rapid floral expansion and senescence. Inflorescence expansion appears to influence partitioning of photoassimilates and storage reserves into transport carbohydrates; under decreased sink demand, the assimilate export rate decreases and photoassimilates are partitioned into starch. The data suggest that sink strength of inflorescences held in darkness may be responsible for the depletion of leaf carbohydrates and. consequently, blackening.

Grapevines under drought do not express esca leaf symptoms

2021 ◽  
Vol 118 (43) ◽  
pp. e2112825118
Author(s):  
Giovanni Bortolami ◽  
Gregory A. Gambetta ◽  
Cédric Cassan ◽  
Silvina Dayer ◽  
Elena Farolfi ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Stress Responses ◽  
Carbon Balance ◽  
Nonstructural Carbohydrates ◽  
Complex Interactions ◽  
Whole Plant ◽  
Underlying Causes ◽  
Abiotic And Biotic Factors ◽  
Leaf Symptoms

In the context of climate change, plant mortality is increasing worldwide in both natural and agroecosystems. However, our understanding of the underlying causes is limited by the complex interactions between abiotic and biotic factors and the technical challenges that limit investigations of these interactions. Here, we studied the interaction between two main drivers of mortality, drought and vascular disease (esca), in one of the world’s most economically valuable fruit crops, grapevine. We found that drought totally inhibited esca leaf symptom expression. We disentangled the plant physiological response to the two stresses by quantifying whole-plant water relations (i.e., water potential and stomatal conductance) and carbon balance (i.e., CO2 assimilation, chlorophyll, and nonstructural carbohydrates). Our results highlight the distinct physiology behind these two stress responses, indicating that esca (and subsequent stomatal conductance decline) does not result from decreases in water potential and generates different gas exchange and nonstructural carbohydrate seasonal dynamics compared to drought.

Impairment of vascular function is associated with an age-related increase of lipid peroxidation in rats

1996 ◽  
Vol 271 (6) ◽  
pp. R1625-R1631 ◽  
Author(s):  
S. T. Davidge ◽  
C. A. Hubel ◽  
M. K. McLaughlin
Keyword(s):  
Nitric Oxide ◽  
Lipid Peroxidation ◽  
Vascular Function ◽  
Mesenteric Arteries ◽  
Relaxation Response ◽  
Female Rat ◽  
Cyclooxygenase Inhibition ◽  
Age Related ◽  
Old Rats ◽  
Over Time

We tested the hypothesis that an increase in endogenous lipid peroxidation over time is associated with an impairment of endothelium-dependent vascular function in resistance-sized mesenteric arteries that is due in part to alterations of arachidonate metabolism. Susceptibility to red blood cell hemolysis and sera levels of malondialdehyde were increased (P < 0.05) from 20 wk (n = 12) to 40 wk (n = 12) in female Sprague-Dawley rats. Arteries were studied in a myograph by examining the endothelial modification of phenylephrine vasoconstriction and the relaxation responses of the mesenteric arteries to methacholine. We observed the following. 1) An increase in sensitivity to alpha 1-adrenergic stimulation occurred between 20 and 40 wk of age. Cyclooxygenase inhibition decreased the sensitivity to phenylephrine only in the arteries from the 40-wk-old rats, indicating that a cyclooxygenase-dependent vasoconstrictor was modifying the phenylephrine response. 2) Nitric oxide synthase inhibition caused a greater increase in phenylephrine sensitivity in the arteries from the 20-wk-old rats than those from the 40-wk-old rats, indicating that nitric oxide modification of phenylephrine sensitivity decreased with age. 3) Endothelium-independent relaxations were not affected between 20 and 40 wk of age. 4) At 40 wk, the sensitivity to the methacholine-mediated relaxation response decreased without impairing the maximal relaxation response. This reduced sensitivity was removed with cyclooxygenase inhibition or thromboxane A2/prostaglandin H2 (PGH2) receptor blockade. 5) Aortas from the 40-wk-old rats had an increased expression of PGH synthase. Collectively, these observations indicate that, in the female rat, an increase in lipid peroxidation over time is associated with changes in endothelium-dependent vascular function that were due in part to a cyclooxygenase-dependent vasoconstrictor.

scholarly journals Response of Bean (Vicia faba L.) Plants to Low Sink Demand by Measuring the Gas Exchange Rates and Chlorophyll a Fluorescence Kinetics

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e80770 ◽  
Author(s):  
Bo-Fang Yan ◽  
Wei Duan ◽  
Guo-Tian Liu ◽  
Hong-Guo Xu ◽  
Li-Jun Wang ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Chlorophyll A ◽  
Vicia Faba ◽  
Chlorophyll A Fluorescence ◽  
Fluorescence Kinetics ◽  
Vicia Faba L ◽  
Sink Demand

Breeding durum wheat in western Canada: Historical trends in yield and related variables

1995 ◽  
Vol 75 (1) ◽  
pp. 55-60 ◽  
Author(s):  
T. N. McCaig ◽  
J. M. Clarke
Keyword(s):  
Durum Wheat ◽  
Triticum Turgidum ◽  
Kernel Weight ◽  
Western Canada ◽  
Kernel Number ◽  
Historical Trends ◽  
Days To Maturity ◽  
Sink Demand ◽  
Over Time ◽  
Selection Of

Canadian durum wheat (Triticum turgidum L.) production is centred in the Brown and Dark Brown soil zones, areas of limited rainfall. For more than 50 yr, lines have been evaluated in the multi-location Durum Cooperative Test. Data from this test, over the period 1947–1992, were analyzed with the objectives of determining the advances that have been made within the Canada Western Amber Durum (CWAD) wheat class and comparing yield-related variables of recently registered cultivars with those of earlier cultivars. Canadian-developed cultivars have increased yields about 0.81% yr−1 relative to Hercules, or approximately 22.6 kg ha−1 yr−1. As kernel weight has remained unchanged, the genetic yield increases have resulted entirely from an increase in the number of kernels produced. Because kernel number is determined prior to, and during, anthesis, further yield increases may depend upon selection of genotypes that produce higher numbers of kernels, thereby increasing sink demand. While plant height and hectolitre weight have been decreasing over time, neither variable was significantly (P < 0.05) correlated with the yield increases that have taken place over the 29-yr period. The selection pressure toward shorter cultivars may have involved other agronomic advantages, such as decreased lodging. Days to maturity did not change significantly over time and was not correlated with yield. Key words:Triticum turgidum, kernel number, kernel weight, height, hectolitre weight

No difference in leaf respiration rates among temperate, subarctic, and arctic species grown under controlled conditions

1996 ◽  
Vol 74 (2) ◽  
pp. 317-320 ◽  
Author(s):  
Donald E. Collier
Keyword(s):  
Growth Temperature ◽  
Alternative Pathway ◽  
Geographic Origin ◽  
Temperature Acclimation ◽  
Temperate Species ◽  
Leaf Respiration ◽  
Arctic Species ◽  
Respiration Rates ◽  
Controlled Conditions ◽  
Plant Groups

To test the theory that leaf respiration rates are inherently higher in arctic species compared with temperate species, a total of 35 species from temperate, subarctic, and arctic locations were grown under controlled conditions and leaf respiration rates were measured. Regardless of growth temperature (either 10 or 20 °C), leaf respiration rates measured at the growth temperature were independent of a species' geographic origin. In addition, salicylhydroxamic acid inhibited the alternative oxidase equally in all groups of species. Acclimation of leaf respiration to temperature was observed in all three geographic plant groups, i.e., leaf respiration rates of 20 °C-grown plants were not significantly different than rates of 10 °C-grown plants when respiration was measured at the growth temperature. These results suggest that arctic species do not have inherently high leaf respiration rates, higher alternative pathway respiration, or greater temperature acclimation ability compared with temperate species. Keywords: alternative pathway respiration, arctic, leaf respiration, subarctic, temperate, temperature.

Corrigendum to "Lipid peroxidation, catalase activity and metallothionein levels in female and male MSG-treated mice over time" [Free Rad. Bio. Med. 65 (Suppl. 2) (2013) S115]

2014 ◽  
Vol 68 ◽  
pp. 258
Author(s):  
R.J. Hernández-Bautista ◽  
E. González Guzmán ◽  
M.C. .Escobar Villanueva ◽  
F.J. Alarcón-Aguilar ◽  
E. Brambila ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Catalase Activity ◽  
Over Time

scholarly journals LEAF BLACKENING IN PROTEA NERIIFOLIA R. BR.

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1087c-1087
Author(s):  
Robyn McConchie ◽  
N. Suzanne Robbins
Keyword(s):  
Exchange Rates ◽  
Carbohydrate Metabolism ◽  
Flower Development ◽  
Baton Rouge ◽  
Distilled Water ◽  
Nonstructural Carbohydrates ◽  
Leaf Quality ◽  
Flower Diameter ◽  
Number Of Leaves ◽  
Black Flower

Leaf blackening of Protea neriifolia is a common postharvest problem which renders flowers unsalable. Previous reports suggest that depletion of carbohydrates in source leaves caused by transfer of carbohydrates to the strong flower sink may be a major cause. Flowering stems of P. neriifolia were harvested in California under standard conditions and shipped to Baton Rouge, La. Upon arrival, the stems were re-cut (1 cm.), the number of leaves counted and the diameter and height of the flowers measured. Stems were transferred to 1 liter deionized distilled water containing 50 ppm hypochlorite, and 0.5% sucrose or no sucrose, and placed in a growth chamber (25°C) either with 12 hrs light (120 μmol/m2/s), or 24 hrs darkness. Number of leaves 10% black, flower diameter and height, and carbon exchange rates were measured every two days over a 16 day interval. Soluble and insoluble nonstructural carbohydrates were determined and assimilate export rate was estimated for each sampling day. Stems placed in the light maintained healthy foliage while those in the dark had 77-l00% of their leaves 10% black by day 8. Flower and leaf quality in the fight treatment were superior with addition of sucrose to the vase solution. Influence of treatments on carbohydrate metabolism in relation to leaf blackening and flower development will be discussed.

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