NaCl-induced effects on photosynthesis, ion relations, and growth of Chloris gayana Kunth in the presence of two levels of KCl.

Soil salinization is a widespread environmental problem that impacts agriculture. Potassium fertilization is often associated with stress mitigation. Aiming to identify the ability of Rhodes grass (Chloris gayana Kunth) to cope with high salt as well as to investigate the potential of K fertilization to alleviate stress symptoms, we investigated the combined effects of NaCl and KCl on photosynthesis, ion distribution, and growth of two Rhodes grass cultivars, Callide and Reclaimer.

Salt tolerance in mungbean is associated with controlling Na and Cl transport across roots, regulating Na and Cl accumulation in chloroplasts and maintaining high K in root and leaf mesophyll cells.

Salinity tolerance requires coordinated responses encompassing salt exclusion in roots and tissue/cellular compartmentation of salt in leaves. We investigated the possible control points for salt ions transport in roots and tissue tolerance to Na and Cl in leaves of two contrasting mungbean genotypes, salt-tolerant Jade AU and salt-sensitive BARI Mung-6, grown in nonsaline and saline (75 mM NaCl) soil. Cryo-SEM X-ray microanalysis was used to determine concentrations of Na, Cl, K, Ca, Mg, P, and S in various cell types in roots related to the development of apoplastic barriers, and in leaves related to photosynthetic performance.

Salt tolerance in relation to elemental concentrations in leaf cell vacuoles and chloroplasts of a C monocotyledonous halophyte.

Halophytes accumulate and sequester high concentrations of salt in vacuoles while maintaining lower levels of salt in the cytoplasm. The current data on cellular and subcellular partitioning of salt in halophytes are, however, limited to only a few dicotyledonous C species. Using cryo-scanning electron microscopy X-ray microanalysis, we assessed the concentrations of Na, Cl, K, Ca, Mg, P and S in various cell types within the leaf-blades of a monocotyledonous C halophyte, Rhodes grass (Chloris gayana).

Novel Salinity Tolerance Loci in Chickpea Identified in Glasshouse and Field Environments.

A better understanding of the genetics of salinity tolerance in chickpea would enable breeding of salt tolerant varieties, offering potential to expand chickpea production to marginal, salinity-affected areas. A Recombinant Inbred Line population was developed using accelerated-Single Seed Descent of progeny from a cross between two chickpea varieties, Rupali (salt-sensitive) and Genesis836 (salt-tolerant). The population was screened for salinity tolerance using high-throughput image-based phenotyping in the glasshouse, in hydroponics, and across 2 years of field trials at Merredin, Western Australia.

Na and/or Cl Toxicities Determine Salt Sensitivity in Soybean ( (L.) ), Mungbean ( (L.) R. Wilczek), Cowpea ( (L.) ), and Common Bean ( L.).

Grain legumes are important crops, but they are salt sensitive. This research dissected the responses of four (sub)tropical grain legumes to ionic components (Na and/or Cl) of salt stress. Soybean, mungbean, cowpea, and common bean were subjected to NaCl, Na salts (without Cl), Cl salts (without Na), and a "high cation" negative control for 57 days.

The barrier to radial oxygen loss impedes the apoplastic entry of iron into the roots of Urochloa humidicola.

Lack of O2 and high concentrations of iron (Fe) and manganese (Mn) commonly occur in waterlogged soils. The development of a barrier to impede radial O2 loss (ROL) is a key trait improving internal O2 transport and waterlogging tolerance in plants. We evaluated the ability of the barrier to ROL to impede the entry of excess Fe into the roots of the waterlogging-tolerant grass Urochloa humidicola.

Root length is proxy for high-throughput screening of waterlogging tolerance in Urochloa spp. grasses.

C4 perennial Urochloa spp. grasses are widely planted in extensive areas in the tropics. These areas are continuously facing waterlogging events, which limits plant growth and production.

Role of roots in adaptation of soil-indifferent Proteaceae to calcareous soils in south-western Australia.

Very few of the >650 Proteaceae species in south-western Australia cope with the high calcium (Ca) levels in young, calcareous soils (soil indifferent); most are Ca sensitive and occur on nutrient-impoverished, acidic soils (calcifuge). We assessed possible control points for Ca transport across roots of two soil-indifferent (Hakea prostrata and Banksia prionotes) and two calcifuge (H. incrassata and B.

Improving crop salt tolerance using transgenic approaches: An update and physiological analysis.

Salinization of land is likely to increase due to climate change with impact on agricultural production. Since most species used as crops are sensitive to salinity, improvement of salt tolerance is needed to maintain global food production. This review summarises successes and failures of transgenic approaches in improving salt tolerance in crop species.

Submergence tolerance and recovery in Lotus: Variation among fifteen accessions in response to partial and complete submergence.

Several Lotus species are perennial forage legumes which tolerate waterlogging, but knowledge of responses to partial or complete shoot submergence is scant. We evaluated the responses of 15 Lotus accessions to partial and complete shoot submergence and variations in traits associated with tolerance and recovery after de-submergence. Accessions of Lotus tenuis, L.

A novel adaptation facilitates seed establishment under marine turbulent flows.

Seeds of Australian species of the seagrass genus Posidonia are covered by a membranous wing that we hypothesize plays a fundamental role in seed establishment in sandy, wave swept marine environments. Dimensions of the seed and membrane were quantified under electron microscopy and micro-CT scans, and used to model rotational, drag and lift forces. Seeds maintain contact with the seabed in the presence of strong turbulence: the larger the wing, the more stable the seed.

Root O consumption, CO production and tissue concentration profiles in chickpea, as influenced by environmental hypoxia.

Roots in flooded soils experience hypoxia, with the least O in the vascular cylinder. Gradients in CO across roots had not previously been measured. The respiratory quotient (RQ; CO produced : O consumed) is expected to increase as O availability declines.

Root-zone hypoxia reduces growth of the tropical forage grass Urochloa humidicola in high-nutrient but not low-nutrient conditions.

Background And Aims: The perennial C4 grass Urochloa humidicola is widely planted on infertile acidic and waterlogging-prone soils of tropical America. Waterlogging results in soil anoxia, and O2 deficiency can reduce nutrient uptake by roots. Interestingly, both nutrient deficiencies and soil waterlogging can enhance root cortical cell senescence, and the increased gas-filled porosity facilitates internal aeration of roots.

Salinity tolerance in chickpea is associated with the ability to 'exclude' Na from leaf mesophyll cells.

Salinity tolerance is associated with Na 'exclusion' from, or 'tissue tolerance' in, leaves. We investigated whether two contrasting chickpea genotypes, salt-tolerant Genesis836 and salt-sensitive Rupali, differ in leaf tissue tolerance to NaCl. We used X-ray microanalysis to evaluate cellular Na, Cl, and K concentrations in various cell types within leaflets and also in secretory trichomes of the two chickpea genotypes in relation to photosynthesis in control and saline conditions.

Rice acclimation to soil flooding: Low concentrations of organic acids can trigger a barrier to radial oxygen loss in roots.

Waterlogged soils contain monocarboxylic acids produced by anaerobic microorganisms. These "organic acids" can accumulate to phytotoxic levels and promote development of a barrier to radial O loss (ROL) in roots of some wetland species. Environmental cues triggering root ROL barrier induction, a feature that together with tissue gas-filled porosity facilitates internal aeration, are important to elucidate for knowledge of plant stress physiology.

Root phenotypes of dwarf and "overgrowth" SLN1 barley mutants, and implications for hypoxic stress tolerance.

Gibberellins are central to the regulation of plant development and growth. Action of gibberellins involves the degradation of DELLA proteins, which are negative regulators of growth. In barley (Hordeum vulgare), certain mutations affecting genes involved in gibberellin synthesis or coding for the barley DELLA protein (Sln1) confer dwarfism.

Tolerance to partial and complete submergence in the forage legume Melilotus siculus: an evaluation of 15 accessions for petiole hyponastic response and gas-filled spaces, leaf hydrophobicity and gas films, and root phellem.

Background And Aims: Submergence is a severe stress for most plants. Melilotus siculus is a waterlogging- (i.e.

Anatomical and biochemical characterisation of a barrier to radial O loss in adventitious roots of two contrasting Hordeum marinum accessions.

A barrier to radial O2 loss (ROL) in roots is an adaptive trait of waterlogging-tolerant plants. Hordeum marinum Huds. is a waterlogging-tolerant species that, in contrast to its waterlogging-sensitive cultivated relatives, forms a tight barrier to ROL in basal root zones.

Photosynthetic response to globally increasing CO2 of co-occurring temperate seagrass species.

Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) .

Oxygen deficiency and salinity affect cell-specific ion concentrations in adventitious roots of barley (Hordeum vulgare).

Oxygen deficiency associated with soil waterlogging adversely impacts root respiration and nutrient acquisition. We investigated the effects of O2 deficiency and salinity (100 mM NaCl) on radial O2 concentrations and cell-specific ion distributions in adventitious roots of barley (Hordeum vulgare). Microelectrode profiling measured O2 concentrations across roots in aerated, aerated saline, stagnant or stagnant saline media.

Salt sensitivity in chickpea (Cicer arietinum L.): ions in reproductive tissues and yield components in contrasting genotypes.

The reproductive phase in chickpea (Cicer arietinum L.) is affected by salinity, but little is known about the underlying cause. We investigated whether high concentrations of Na(+) and Cl(-) in the reproductive structures influence reproductive processes.

Effects of organic acids on the formation of the barrier to radial oxygen loss in roots of Hordeum marinum.

A barrier to radial O2 loss (ROL) is an adaptive trait of many wetland plants, yet the signal(s) for barrier induction remain uncertain. We assessed the effects of monocarboxylic acids produced in waterlogged soils (acetic, propionic, N-butyric and caproic acids) on barrier formation in adventitious roots of the waterlogging tolerant Hordeum marinum Huds. These acids were applied in nutrient solution either individually (at 0.

Enhanced formation of aerenchyma and induction of a barrier to radial oxygen loss in adventitious roots of Zea nicaraguensis contribute to its waterlogging tolerance as compared with maize (Zea mays ssp. mays).

Enhancement of oxygen transport from shoot to root tip by the formation of aerenchyma and also a barrier to radial oxygen loss (ROL) in roots is common in waterlogging-tolerant plants. Zea nicaraguensis (teosinte), a wild relative of maize (Zea mays ssp. mays), grows in waterlogged soils.

Mechanisms for coping with submergence and waterlogging in rice.

Rice (Oryza sativa L.), unlike other cereals, can grow well in paddy fields and is highly tolerant of excess water stress, from either submergence (in which part or all of the plant is under water) or waterlogging (in which excess water in soil limits gas diffusion). Rice handles submergence stress by internal aeration and growth controls.

Apoplastic barriers effectively block oxygen permeability across outer cell layers of rice roots under deoxygenated conditions: roles of apoplastic pores and of respiration.

*Despite the importance of the barrier to oxygen losses of the roots of hygrophytes growing in wet environments devoid of oxygen, there are few data available on permeability coefficients for O(2) across outer root cell layers (P(OPR)) and how they may change in response to low O(2). *A gas perfusion technique was used to measure the P(OPR) of rice (Oryza sativa) plants grown in either aerated or deoxygenated solution. The contributions of the apoplast and of living cells to the overall P(OPR) were characterized either by blocking apoplastic pores with precipitates of brown Cu(2)[Fe(CN)(6)] or by killing cells with 0.