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M D Burchett - One of the best experts on this subject based on the ideXlab platform.
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accumulation and distribution of heavy metals in the grey mangrove Avicennia Marina forsk vierh biological indication potential
Environmental Pollution, 2003Co-Authors: Geoff R Macfarlane, Alex Pulkownik, M D BurchettAbstract:The accumulative partitioning of the heavy metals Cu, Pb and Zn in the grey mangrove, Avicennia Marina, were studied under field conditions. Copper and Pb were accumulated in root tissue to levels higher than surrounding sediment levels. Zinc was accumulated to levels reflecting sediment concentrations. Strong linear relationships existed for all metals in sediments with metals in root tissue. Accumulation of Cu in leaf tissue followed a linear relationship at lower sediment concentrations, with an exclusion or saturation mechanism at higher sediment concentrations. Lead showed little mobility to leaf tissue. Zn showed restricted accumulation in leaf tissue, which correlated with sediment concentrations. Decreases in sediment pH were found to increase Zn accumulation to root tissue. Increasing concentrations of Pb and Zn in sediments resulted in a greater accumulation of Pb to both root and leaf tissue. A. Marina roots may be employed as a biological indicator of environmental exposure of Cu, Pb and Zn and leaves for Zn, with temporal monitoring.
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toxicity growth and accumulation relationships of copper lead and zinc in the grey mangrove Avicennia Marina forsk vierh
Marine Environmental Research, 2002Co-Authors: Geoff R Macfarlane, M D BurchettAbstract:Abstract The effects of three heavy metals Copper (Cu), lead (Pb) and zinc (Zn), and the interaction of an essential (Zn) and non-essential (Pb) metal on germination, growth, and accumulation of metals in the grey mangrove, Avicennia Marina (Forsk.) Vierh var. australasica (Walp.) Moldenke, were studied under laboratory conditions. Avicennia Marina was found to be highly tolerant to the metals applied. Copper was accumulated in root tissue in a linear relationship at lower sediment concentrations, but at concentrations of 200 μg/g and higher, no further increases in root Cu levels occurred. Translocation of Cu from the root to leaf tissue was low, yet revealed similar accumulation patterns as root tissue. Significant reductions in seedling height leaf number and area were found with significant increases in Cu concentrations in tissues at 100 μg/g sediment Cu. At Cu sediment levels of 400 μg/g, a decrease in total biomass and root growth inhibition was observed. Emergence was retarded with increasing copper concentration, with 800 μg/g sediment Cu resulting in a total inhibition of emergence. The LC 50 for emergence and EC 50 for biomass was 566 and 380 μg/g Cu respectively. Lead accumulation in root tissue was lower that other metals, yet increased in a dose dependant fashion across the sediment Pb concentration range examined. Lead was excluded from leaf tissue at Pb sediment concentrations up to 400 μg/g, above which limited transport of Pb occurred. Little negative effects on growth were observed due to the low accumulation of Pb. Zinc uptake was high, and was accumulated in a linear fashion in root tissue across the sediment Zn concentration range applied. Zinc translocation to leaf tissue exhibited a dose dependant relationship with both root and sediment Zn levels. Emergence decreased with increasing sediment Zn concentrations, with 1000 μg/g sediment Zn showing 100% mortality. Significant reductions in seedling height, leaf number, area, biomass and root growth inhibition were found at concentrations of 500 μg/g sediment Zn. The LC 50 for emergence and EC 50 for biomass was 580 and 392 μg/g Zn respectively. Lead and Zn in combination resulted in an increased accumulation of both metals in leaf tissue and increased toxicity than individual metals alone, and is the first noted occurrence of a Pb and Zn additive response in angiosperms. Possible mechanisms of accumulation and toxicity are discussed.
Marilyn C Ball - One of the best experts on this subject based on the ideXlab platform.
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harvesting water from unsaturated atmospheres deliquescence of salt secreted onto leaf surfaces drives reverse sap flow in a dominant arid climate mangrove Avicennia Marina
New Phytologist, 2021Co-Authors: Hoa T Nguyen, Lawren Sack, Rafael S Oliveira, Rafael E Coopman, Maurizio Mencuccini, Catherine E Lovelock, Marilyn C BallAbstract:The mangrove Avicennia Marina adjusts internal salt concentrations by foliar salt secretion. Deliquescence of accumulated salt causes leaf wetting that may provide a water source for salt-secreting plants in arid coastal wetlands where high nocturnal humidity can usually support deliquescence whereas rainfall events are rare. We tested the hypotheses that salt deliquescence on leaf surfaces can drive top-down rehydration, and that such absorption of moisture from unsaturated atmospheres makes a functional contribution to dry season shoot water balances. Sap flow and water relations were monitored to assess the uptake of atmospheric water by branches during shoot wetting events under natural and manipulated microclimatic conditions. Reverse sap flow rates increased with increasing relative humidity from 70% to 89%, consistent with function of salt deliquescence in harvesting moisture from unsaturated atmospheres. Top-down rehydration elevated branch water potentials above those possible from root water uptake, subsidising transpiration rates and reducing branch vulnerability to hydraulic failure in the subsequent photoperiod. Absorption of atmospheric moisture harvested through deliquescence of salt on leaf surfaces enhances water balances of Avicennia Marina growing in hypersaline wetlands under arid climatic conditions. Top-down rehydration from these frequent, low intensity wetting events contributes to prevention of carbon starvation and hydraulic failure during drought.
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shoot surface water uptake enables leaf hydraulic recovery in Avicennia Marina
New Phytologist, 2019Co-Authors: Tomas I Fuenzalida, Lawren Sack, Rafael S Oliveira, Callum J Bryant, Leuwin I Ovington, Hwanjin Yoon, Marilyn C BallAbstract:The significance of shoot surface water uptake (SSWU) has been debated, and it would depend on the range of conditions under which it occurs. We hypothesized that the decline of leaf hydraulic conductance (Kleaf ) in response to dehydration may be recovered through SSWU, and that the hydraulic conductance to SSWU (Ksurf ) declines with dehydration. We quantified effects of leaf dehydration on Ksurf and effects of SSWU on recovery of Kleaf in dehydrated leaves of Avicennia Marina. SSWU led to overnight recovery of Kleaf , with recovery retracing the same path as loss of Kleaf in response to dehydration. SSWU declined with dehydration. By contrast, Ksurf declined with rehydration time but not with dehydration. Our results showed a role of SSWU in the recovery of leaf hydraulic conductance and revealed that SSWU is sensitive to leaf hydration status. The prevalence of SSWU in vegetation suggests an important role for atmospheric water sources in maintenance of leaf hydraulic function, with implications for plant responses to changing environments.
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leaf water storage increases with salinity and aridity in the mangrove Avicennia Marina integration of leaf structure osmotic adjustment and access to multiple water sources
Plant Cell and Environment, 2017Co-Authors: Hoa T Nguyen, Patrick Meir, Lawren Sack, John R Evans, Rafael S Oliveira, Marilyn C BallAbstract:Leaf structure and water relations were studied in a temperate population of Avicennia Marina subsp. australasica along a natural salinity gradient [28 to 49 parts per thousand (ppt)] and compared with two subspecies grown naturally in similar soil salinities to those of subsp. australasica but under different climates: subsp. eucalyptifolia (salinity 30 ppt, wet tropics) and subsp. Marina (salinity 46 ppt, arid tropics). Leaf thickness, leaf dry mass per area and water content increased with salinity and aridity. Turgor loss point declined with increase in soil salinity, driven mainly by differences in osmotic potential at full turgor. Nevertheless, a high modulus of elasticity (e) contributed to maintenance of high cell hydration at turgor loss point. Despite similarity among leaves in leaf water storage capacitance, total leaf water storage increased with increasing salinity and aridity. The time that stored water alone could sustain an evaporation rate of 1 mmol m-2 s-1 ranged from 77 to 126 min from subspecies eucalyptifolia to ssp. Marina, respectively. Achieving full leaf hydration or turgor would require water from sources other than the roots, emphasizing the importance of multiple water sources to growth and survival of Avicennia Marina across gradients in salinity and aridity.
Geoff R Macfarlane - One of the best experts on this subject based on the ideXlab platform.
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accumulation and distribution of heavy metals in the grey mangrove Avicennia Marina forsk vierh biological indication potential
Environmental Pollution, 2003Co-Authors: Geoff R Macfarlane, Alex Pulkownik, M D BurchettAbstract:The accumulative partitioning of the heavy metals Cu, Pb and Zn in the grey mangrove, Avicennia Marina, were studied under field conditions. Copper and Pb were accumulated in root tissue to levels higher than surrounding sediment levels. Zinc was accumulated to levels reflecting sediment concentrations. Strong linear relationships existed for all metals in sediments with metals in root tissue. Accumulation of Cu in leaf tissue followed a linear relationship at lower sediment concentrations, with an exclusion or saturation mechanism at higher sediment concentrations. Lead showed little mobility to leaf tissue. Zn showed restricted accumulation in leaf tissue, which correlated with sediment concentrations. Decreases in sediment pH were found to increase Zn accumulation to root tissue. Increasing concentrations of Pb and Zn in sediments resulted in a greater accumulation of Pb to both root and leaf tissue. A. Marina roots may be employed as a biological indicator of environmental exposure of Cu, Pb and Zn and leaves for Zn, with temporal monitoring.
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toxicity growth and accumulation relationships of copper lead and zinc in the grey mangrove Avicennia Marina forsk vierh
Marine Environmental Research, 2002Co-Authors: Geoff R Macfarlane, M D BurchettAbstract:Abstract The effects of three heavy metals Copper (Cu), lead (Pb) and zinc (Zn), and the interaction of an essential (Zn) and non-essential (Pb) metal on germination, growth, and accumulation of metals in the grey mangrove, Avicennia Marina (Forsk.) Vierh var. australasica (Walp.) Moldenke, were studied under laboratory conditions. Avicennia Marina was found to be highly tolerant to the metals applied. Copper was accumulated in root tissue in a linear relationship at lower sediment concentrations, but at concentrations of 200 μg/g and higher, no further increases in root Cu levels occurred. Translocation of Cu from the root to leaf tissue was low, yet revealed similar accumulation patterns as root tissue. Significant reductions in seedling height leaf number and area were found with significant increases in Cu concentrations in tissues at 100 μg/g sediment Cu. At Cu sediment levels of 400 μg/g, a decrease in total biomass and root growth inhibition was observed. Emergence was retarded with increasing copper concentration, with 800 μg/g sediment Cu resulting in a total inhibition of emergence. The LC 50 for emergence and EC 50 for biomass was 566 and 380 μg/g Cu respectively. Lead accumulation in root tissue was lower that other metals, yet increased in a dose dependant fashion across the sediment Pb concentration range examined. Lead was excluded from leaf tissue at Pb sediment concentrations up to 400 μg/g, above which limited transport of Pb occurred. Little negative effects on growth were observed due to the low accumulation of Pb. Zinc uptake was high, and was accumulated in a linear fashion in root tissue across the sediment Zn concentration range applied. Zinc translocation to leaf tissue exhibited a dose dependant relationship with both root and sediment Zn levels. Emergence decreased with increasing sediment Zn concentrations, with 1000 μg/g sediment Zn showing 100% mortality. Significant reductions in seedling height, leaf number, area, biomass and root growth inhibition were found at concentrations of 500 μg/g sediment Zn. The LC 50 for emergence and EC 50 for biomass was 580 and 392 μg/g Zn respectively. Lead and Zn in combination resulted in an increased accumulation of both metals in leaf tissue and increased toxicity than individual metals alone, and is the first noted occurrence of a Pb and Zn additive response in angiosperms. Possible mechanisms of accumulation and toxicity are discussed.
Ajay Parida - One of the best experts on this subject based on the ideXlab platform.
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an oxidative and salinity stress induced peroxisomal ascorbate peroxidase from Avicennia Marina molecular and functional characterization
Plant Physiology and Biochemistry, 2008Co-Authors: Kumaresan Kavitha, Gayatri Venkataraman, Ajay ParidaAbstract:Abstract APX (EC, 1.11.1.11) has a key role in scavenging ROS and in protecting cells against their toxic effects in algae and higher plants. A cDNA encoding a peroxisomal ascorbate peroxidase, Am-pAPX1 , was isolated from salt stressed leaves of Avicennia Marina (Forsk.) Vierh. by EST library screening and its expression in the context of various environmental stresses was investigated. Am-pAPX1 contains an ORF of 286 amino acids coding for a 31.4 kDa protein. The C-terminal region of the Am-pAPX1 ORF has a putative transmembrane domain and a peroxisomal targeting signal (RKKMK), suggesting peroxisomal localization. The peroxisomal localization of Am-pAPX1 was confirmed by stable transformation of the GFP-(Ala) 10 - Am-pAPX1 fusion in tobacco. RNA blot analysis revealed that Am-pAPX1 is expressed in response to salinity (NaCl) and oxidative stress (high intensity light, hydrogen peroxide application and excess iron). The isolated genomic clone of Am-pAPX1 was found to contain nine exons. A fragment of 1616 bp corresponding to the 5′ upstream region of Am-pAPX1 was isolated by TAIL-PCR. In silico analysis of this sequence reveals the presence of putative light and abiotic stress regulatory elements.
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generation and analysis of expressed sequence tags from the salt tolerant mangrove species Avicennia Marina forsk vierh
Theoretical and Applied Genetics, 2005Co-Authors: Preeti Mehta, Gayatri Venkataraman, K R Sivaprakash, Madasamy Parani, Ajay ParidaAbstract:Salinization poses an increasingly serious problem in coastal and agricultural areas with negative effects on plant productivity and yield. Avicennia Marina is a pantropical mangrove species that can survive in highly saline conditions. As a first step towards the characterization of genes that contribute to combating salinity stress, the construction of a cDNA library of A. Marina genes is reported here. Random expressed sequence tag (EST) sequencing of 1,841 clones produced 1,602 quality reads. These clones were classified into functional categories, and blast comparisons revealed that 113 clones were homologous to genes earlier implicated in stress responses, of which the dehydrins are the most predominant in this category. Of the ESTs analyzed, 30% showed homology to previously uncharacterized genes in the public plant databases. Of these 30%, 52 clones were selected for reverse Northern analysis: 26 were shown to be up-regulated and five shown to be down-regulated. The results obtained by reverse Northern analysis were confirmed by Northern analysis for three clones.
Catherine E Lovelock - One of the best experts on this subject based on the ideXlab platform.
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harvesting water from unsaturated atmospheres deliquescence of salt secreted onto leaf surfaces drives reverse sap flow in a dominant arid climate mangrove Avicennia Marina
New Phytologist, 2021Co-Authors: Hoa T Nguyen, Lawren Sack, Rafael S Oliveira, Rafael E Coopman, Maurizio Mencuccini, Catherine E Lovelock, Marilyn C BallAbstract:The mangrove Avicennia Marina adjusts internal salt concentrations by foliar salt secretion. Deliquescence of accumulated salt causes leaf wetting that may provide a water source for salt-secreting plants in arid coastal wetlands where high nocturnal humidity can usually support deliquescence whereas rainfall events are rare. We tested the hypotheses that salt deliquescence on leaf surfaces can drive top-down rehydration, and that such absorption of moisture from unsaturated atmospheres makes a functional contribution to dry season shoot water balances. Sap flow and water relations were monitored to assess the uptake of atmospheric water by branches during shoot wetting events under natural and manipulated microclimatic conditions. Reverse sap flow rates increased with increasing relative humidity from 70% to 89%, consistent with function of salt deliquescence in harvesting moisture from unsaturated atmospheres. Top-down rehydration elevated branch water potentials above those possible from root water uptake, subsidising transpiration rates and reducing branch vulnerability to hydraulic failure in the subsequent photoperiod. Absorption of atmospheric moisture harvested through deliquescence of salt on leaf surfaces enhances water balances of Avicennia Marina growing in hypersaline wetlands under arid climatic conditions. Top-down rehydration from these frequent, low intensity wetting events contributes to prevention of carbon starvation and hydraulic failure during drought.
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influence of temporospatial variation in sap flux density on estimates of whole tree water use in Avicennia Marina
Trees-structure and Function, 2015Co-Authors: Bart A E Van De Wal, Catherine E Lovelock, Adrien Guyot, D A Lockington, Kathy SteppeAbstract:Our study shows that sap flow in Avicennia Marina varies significantly throughout the sapwood and that spatial patterns in sap flux density are dependent on meteorological conditions. Sap flux density measurements are used worldwide as a relatively inexpensive means to provide estimates of whole-tree and whole-stand water use in forest ecosystems. However, erroneous upscaling from point measurements to the entire sapwood area remains an issue, since sap flow is hardly ever constant throughout the tree. In this study, two widely used sap flow methodologies (the Heat Ratio or HR method and the Heat Field Deformation or HFD method) are used to assess radial and azimuthal variations in sap flux density in three mature trees of the mangrove species Avicennia Marina in Brisbane, Australia. The genus Avicennia is characterised by secondary growth via successive cambia, resulting in an atypical sapwood pattern of xylem patches braided with phloem strings. Water use estimates were calculated in different ways. At first, spatial variation was ignored when upscaling from point measurements. Then, radial and azimuthal variations were incorporated subsequently by measuring at different depths and aspects around the tree. Ignoring azimuthal variation led to over- or underestimations of up to 102 %, while radial variation accounted for discrepancies of up to 25 %. Furthermore, the influence of changing meteorological conditions was assessed, which showed that radial profiles changed in shape during rain events, such that maximum sap flow rates occurred at different depths compared to dry periods. Our study thus indicates that spatial variation in sap flux density is highly unpredictable in A. Marina due to its hydraulic architecture, and that changing meteorological conditions alter the pattern of this variation. These two factors should be accounted for when assessing whole-tree water use.
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the use of fresh and saline water sources by the mangrove Avicennia Marina
Hydrobiologia, 2015Co-Authors: Catherine E Lovelock, D A Lockington, Nadia S Santini, Ruth ReefAbstract:Mangroves are distributed along tropical and subtropical riverine and coastal shores. Although mangroves are highly adapted to saline environments, maintaining water uptake under saline conditions is energetically expensive. Therefore, salinity is a lim- iting factor for mangrove growth and productivity, and access to fresh water sources, such as rainwater and groundwater, which reduce water salinity, increase mangrove ecosystem productivity. Here, we investi- gated the extent of fresh water utilization by man- groves to better predict current and future mangrove productivity. We used the abundance of 18 O isotope in stem water to assess: (1) the extent of fresh water utilization by Avicennia Marina (Forssk.) Vierh across hydrological settings; and (2) whether growth, mea- sured as increments in stem circumference, is sensitive to variation in rainfall availability. The d 18 O isotopic composition of stem water indicated mangroves use both fresh and saline water sources for metabolic processes. However, our results suggest that the proportion of fresh water used by mangroves increases with the availability of fresh water. Growth of the main stems of trees was correlated with rainfall (r 2 = 0.34 and r 2 = 0.37, P = 0.001). Our results
