Responses of rice to Fe2+ in aerated and stagnant conditions: growth, root porosity and radial oxygen loss barrier

2014 ◽  
Vol 41 (9) ◽  
pp. 922 ◽  
Author(s):  
Jenjira Mongon ◽  
Dennis Konnerup ◽  
Timothy D. Colmer ◽  
Benjavan Rerkasem
Keyword(s):  
Growth Response ◽  
Oryza Sativa L ◽  
Dry Mass ◽  
Root Surface ◽  
Radial Oxygen Loss ◽  
Root Porosity ◽  
Oxygen Loss ◽  
O2 Transport ◽  
Bulk Medium ◽  
Root Aeration

Lowland rice (Oryza sativa L.) encounters flooded soils that are anaerobic and chemically reduced. Exposure of the roots to high soil Fe2+ concentrations can result in toxicity. Internal aeration delivering O2 to submerged roots via the aerenchyma is well understood, but the effect of Fe2+ on O2 transport in roots is less studied. We aimed to evaluate the effects of Fe2+ on growth and root aeration. O. sativa var. Amaroo was grown in aerobic and deoxygenated solutions with 0 mM, 0.18 mM, 0.36 mM, 0.54 mM or 0.72 mM Fe2+ using FeSO4.7H2O and a control with 0.05 mM Fe-EDTA. The treatments were imposed on 14-day-old plants (28–30 days old when harvested). Dry mass, shoot Fe concentration, root porosity and patterns of radial O2 loss (ROL) along roots were determined. In the aerobic solution, where Fe2+ was oxidised in the bulk medium, root dry mass increased with higher Fe2+; this was not the case in stagnant solutions, which had no significant root growth response, although Fe oxidation near the root surface was visible as a precipitate. In the highest Fe2+ treatment, shoot Fe concentrations in aerobic (667 mg kg–1) and stagnant (433 mg kg–1) solutions were below the level for toxicity (700 mg kg–1). Rice responded to high Fe2+ in aerobic conditions by increasing root porosity and inducing strong barriers to ROL. In stagnant conditions, root porosity was already high and the ROL barrier induced, so these root aeration traits were not further influenced by the Fe2+ concentrations applied.

Anatomical Adaptive Strategies to Flooding and Rhizosphere Oxidation in Mangrove Seedlings

1996 ◽  
Vol 44 (3) ◽  
pp. 297 ◽  
Author(s):  
T Youssef ◽  
P Saenger
Keyword(s):  
Root Surface ◽  
Limited Information ◽  
Ground Tissue ◽  
Radial Oxygen Loss ◽  
Waterlogging Tolerance ◽  
Mangrove Species ◽  
Root Porosity ◽  
Oxygen Loss ◽  
Diffusive Resistance ◽  
Mangrove Seedlings

Limited information exists on the relation between the capacity of mangrove seedlings to oxidise the rhizosphere and their differential waterlogging tolerance. Laboratory experiments were conducted to estimate radial oxygen loss (ROL) by the entire root, the area of oxidising sites (AOS) on the root surface, root porosity (POR), and the internal diffusive resistance in the ground tissue of seedlings of six mangrove species that show a differential response to flooding. Radial oxygen loss was extremely low in all viviparous seedlings (0.7-1.5 μmol O2 per cm2AOS per day). Differential tolerance of species coincided with the degree of porosity (14.8-45.7%) and the ability of seedlings to develop barriers to oxygen leakage on the root surface. The percentage area of lacunae in the ground tissue of seedlings of the four viviparous species revealed a constriction of the air flow path at the hypocotyl junction. These findings suggest that: (i) the differential tolerance to waterlogging in mangrove seedlings is not simply based on their ability to oxidise the rhizosphere; (ii) the high diffusive resistance in the hypocotyl junction is likely to affect root aeration when the plant's access to air is limited by partial or total submergence; and (iii) waterlogging tolerance is probably a function of the strategy by which roots conserve oxygen to maintain aerobic metabolism for longer periods during submergence. Implications of these findings in seedlings are discussed in relation to other anatomical and morphological adaptations to waterlogging in mature mangroves.

Evaluation of root porosity and radial oxygen loss of disomic addition lines of Hordeum marinum in wheat

2017 ◽  
Vol 44 (4) ◽  
pp. 400 ◽  
Author(s):  
Dennis Konnerup ◽  
A. l. Imran Malik ◽  
A. K. M. R. Islam ◽  
Timothy David Colmer
Keyword(s):  
Triticum Aestivum L ◽  
Radial Oxygen Loss ◽  
Waterlogging Tolerance ◽  
Root Volume ◽  
Root Porosity ◽  
Oxygen Loss ◽  
Chromosome Addition ◽  
Disomic Addition Lines ◽  
Gas Volume ◽  
Root Aeration

Hordeum marinum Huds. is a waterlogging-tolerant wild relative of wheat (Triticum aestivum L.). Greater root porosity (gas volume per root volume) and formation of a barrier to reduce root radial O2 loss (ROL) contribute to the waterlogging tolerance of H. marinum and these traits are evident in some H. marinum–wheat amphiploids. We evaluated root porosity, ROL patterns and tolerance to hypoxic stagnant conditions for 10 various H. marinum (two accessions) disomic chromosome addition (DA) lines in wheat (two varieties), produced from two H. marinum–wheat amphiploids and their recurrent wheat parents. None of the DA lines had a barrier to ROL or higher root porosity than the wheat parents. Lack of a root ROL barrier in the six DA lines for H. marinum accession H21 in Chinese Spring (CS) wheat indicates that the gene(s) for this trait do not reside on one of these six chromosomes; unfortunately, chromosome 3 of H. marinum has not been isolated in CS. Unlike the H21–CS amphiploid, which formed a partial ROL barrier in roots, the H90–Westonia amphiploid and the four derived DA lines available did not. The unaltered root aeration traits in the available DA lines challenge the strategy of using H. marinum as a donor of these traits to wheat.

Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss

2011 ◽  
Vol 159 (6) ◽  
pp. 1730-1736 ◽  
Author(s):  
M.Y. Wang ◽  
A.K. Chen ◽  
M.H. Wong ◽  
R.L. Qiu ◽  
H. Cheng ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Oryza Sativa L ◽  
Cadmium Accumulation ◽  
Radial Oxygen Loss ◽  
Oxygen Loss

The ability of aquatic macrophytes to increase root porosity and radial oxygen loss determines their resistance to sediment anoxia

2012 ◽  
Vol 46 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Damien G. Lemoine ◽  
Florian Mermillod-Blondin ◽  
Marie-Hélène Barrat-Segretain ◽  
Corinne Massé ◽  
Emmanuel Malet
Keyword(s):  
Aquatic Macrophytes ◽  
Radial Oxygen Loss ◽  
Root Porosity ◽  
Oxygen Loss ◽  
Sediment Anoxia

A lack of aerenchyma and high rates of radial oxygen loss from the root base contribute to the waterlogging intolerance of Brassica napus

1999 ◽  
Vol 26 (1) ◽  
pp. 87 ◽  
Author(s):  
L.A.C.J. Voesenek ◽  
W. Armstrong ◽  
G.M. Bögemann ◽  
T.D. Colmer ◽  
M.P. McDonald
Keyword(s):  
Brassica Napus ◽  
Lateral Roots ◽  
Biomass Accumulation ◽  
Radial Oxygen Loss ◽  
Low Oxygen ◽  
Root Porosity ◽  
Oxygen Loss ◽  
Basal Portion ◽  
Pre Treatment ◽  
Oxygen Profiles

The morphology and physiology of the response of two cultivars of Brassica napus to an anaerobic root medium was investigated. The cultivars Chikuzen and Topas showed a large reduction in growth rate when their roots were exposed to a de-oxygenated stagnant nutrient solution containing 0.1% w/v agar. Older seedlings (11 d old) were more sensitive to stagnant agar, expressed as biomass accumulation, than younger ones (5 d old). Brassica napus was characterized by a constitutively low root porosity (3–5%), typical for plant species with a low tolerance to waterlogging. A hypoxia pre- treatment (16 h; 2.25% O2) before exposure to de-oxygenated stagnant agar had no effect on the final number or length of lateral roots and adventitious roots. Brassica napus cv. Chikuzen is characterized by radial oxygen loss being most at the basal portion of the root, when a strong oxygen sink surrounds the root. Oxygen profiles through laterals of Brassica napus cv. Chikuzen show a typical pattern with low oxygen concentrations in the stele and somewhat higher levels in the cortex. Despite the continuum of intercellular air spaces in the root cortical tissue the lack of aerenchyma and therefore low rates of internal oxygen diffusion restricts root growth in anaerobic media and presumably contributes to the sensitivity of Brassica napus to waterlogging.

Spatial patterns of radial oxygen loss and nitrate net flux along adventitious roots of rice raised in aerated or stagnant solution

2002 ◽  
Vol 29 (12) ◽  
pp. 1475 ◽  
Author(s):  
Michael Rubinigg ◽  
Ineke Stulen ◽  
J. Theo M. Elzenga ◽  
Timothy D. Colmer
Keyword(s):  
Oryza Sativa ◽  
Nutrient Uptake ◽  
Spatial Patterns ◽  
Adventitious Roots ◽  
Oryza Sativa L ◽  
Radial Oxygen Loss ◽  
Oxygen Loss ◽  
Root Zones ◽  
Cell Layers ◽  
Net Flux

Roots of rice (Oryza sativa L.) grown in stagnant de-oxygenated solution contain a 'tight' barrier to radial oxygen loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. It is generally accepted that the barrier to ROL involves anatomical modifications in the apoplast of cell layers exterior to the aerenchyma. A possible drawback of this adaptation is a reduced capacity for nutrient uptake. Whether or not induction of a barrier to ROL influences the capacity of adventitious roots of rice to take up NO3– was determined in the present study, using NO3–-selective microelectrodes. When transferred into O2-free root medium, ROL from positions at 30–50 mm behind the tip of adventitious roots of plants raised in stagnant solution was only 4–6% of the rate from roots of plants raised in aerated solution, indicating the barrier to ROL was induced by growth in stagnant solution. For plants transferred into aerobic nutrient solution containing 0.1 mM NO3–, net NO3– uptake by these root zones, with or without a barrier to ROL, was the same. It is concluded that induction of a barrier to ROL had no effect on the capacity of adventitious roots of rice to take up NO3– from aerobic solution.

Evaluation of root oxygenation and growth in baldcypress in response to short-term soil hypoxia

1994 ◽  
Vol 24 (4) ◽  
pp. 804-809 ◽  
Author(s):  
Hillarius K. Kludze ◽  
S. Reza Pezeshki ◽  
Ronald D. Delaune
Keyword(s):  
Net Photosynthesis ◽  
Soil Conditions ◽  
Growth Responses ◽  
Radial Oxygen Loss ◽  
Short Term ◽  
Aerenchyma Formation ◽  
Root Porosity ◽  
Oxygen Loss ◽  
Soil Redox Potential ◽  
Soil Redox

Seedlings of baldcypress (Taxodiumdistichum (L.) Rich. var. distichum) were grown under laboratory and greenhouse conditions to determine the extent to which short-term soil hypoxia influences root aerenchyma–air space formation (expressed as a percentage of total root volume) and concomitant radial oxygen loss. Subsequent photosynthesis and growth responses were also determined. A colorimetric technique involving the use of Ti3+-citrate, a strong reducing compound, was used to quantify radial oxygen loss from whole root system. Soil redox potential of −250 ± 10 mV resulted in enhancement of both root porosity and radial oxygen loss as much as 3-fold compared with plants under well aerated conditions (515 ± 25 mV). The mean oxygen loss from roots was 1.4 mmol O2•g−1•day−1 in drained plants and 4.6 mmol O2•g−1•d−1 in flooded plants. Mean root porosity was 13.3 and 41.4% in drained and flooded plants, respectively. Stomatal conductance, net photosynthesis, and height growth were adversely affected by reduced soil conditions. Baldcypress exhibited an avoidance mechanism under reduced soil conditions by increasing aerenchyma formation and rhizosphere oxygenation at young ages. This may explain the significance of flooding episodes encountered in young stages in enabling baldcypress saplings and trees to tolerate flooding in later stages of the life cycle.

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