Genetic diversity and candidate genes for transient waterlogging tolerance in mungbean at the germination and seedling stages.

Mungbean [ var. (L.) Wilczek] production in Asia is detrimentally affected by transient soil waterlogging caused by unseasonal and increasingly frequent extreme precipitation events.

Comparative transcriptome analysis reveals molecular regulation of salt tolerance in two contrasting chickpea genotypes.

Salinity is a major abiotic stress that causes substantial agricultural losses worldwide. Chickpea ( L.) is an important legume crop but is salt-sensitive.

Response of Mungbean (cvs. Celera II-AU and Jade-AU) and Blackgram (cv. Onyx-AU) to Transient Waterlogging.

Mungbean [ (L.) Wilczek] and blackgram [ (L.) Hepper] are important crops for smallholder farmers in tropical and subtropical regions.

Tolerance of four grain legume species to waterlogging, hypoxia and anoxia at germination and recovery.

Legume seeds, when relay sown following rice, may suffer from soil waterlogging and the associated hypoxia or even anoxia. This study evaluated the tolerance of grain legume species, grass pea (three genotypes), lentil (two genotypes), faba bean (two genotypes) and field pea (one genotype), to soil waterlogging in a glasshouse, to anoxia and hypoxia in temperature-controlled room at germination and seedling stages. Changes in oxygen in the surface layers of soil, with time after waterlogging, were measured by microelectrode profiling.

Corrigendum: Waterlogging of Winter Crops at Early and Late Stages: Impacts on Leaf Physiology, Growth and Yield.

[This corrects the article DOI: 10.3389/fpls.2018.

Regulation of root adaptive anatomical and morphological traits during low soil oxygen.

Flooding causes oxygen deprivation in soils. Plants adapt to low soil oxygen availability by changes in root morphology, anatomy, and architecture to maintain root system functioning. Essential traits include aerenchyma formation, a barrier to radial oxygen loss, and outgrowth of adventitious roots into the soil or the floodwater.

Lateral roots, in addition to adventitious roots, form a barrier to radial oxygen loss in Zea nicaraguensis and a chromosome segment introgression line in maize.

Plants typically respond to waterlogging by producing new adventitious roots with aerenchyma and many wetland plants form a root barrier to radial O loss (ROL), but it was not known if this was also the case for lateral roots. We tested the hypothesis that lateral roots arising from adventitious roots can form a ROL barrier, using root-sleeving electrodes and O microsensors to assess ROL of Zea nicaraguensis, the maize (Zea mays ssp. mays) introgression line with a locus for ROL barrier formation (introgression line (IL) #468) from Z.

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.

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.

Waterlogging of Winter Crops at Early and Late Stages: Impacts on Leaf Physiology, Growth and Yield.

Waterlogging is expected to increase as a consequence of global climate change, constraining crop production in various parts of the world. This study assessed tolerance to 14-days of early- or late-stage waterlogging of the major winter crops wheat, barley, rapeseed and field pea. Aerenchyma formation in adventitious roots, leaf physiological parameters (net photosynthesis, stomatal and mesophyll conductances, chlorophyll fluorescence), shoot and root growth during and after waterlogging, and seed production were evaluated.

Rice leaf hydrophobicity and gas films are conferred by a wax synthesis gene (LGF1) and contribute to flood tolerance.

Floods impede gas (O and CO ) exchange between plants and the environment. A mechanism to enhance plant gas exchange under water comprises gas films on hydrophobic leaves, but the genetic regulation of this mechanism is unknown. We used a rice mutant (dripping wet leaf 7, drp7) which does not retain gas films on leaves, and its wild-type (Kinmaze), in gene discovery for this trait.

Waterlogging tolerance, tissue nitrogen and oxygen transport in the forage legume Melilotus siculus: a comparison of nodulated and nitrate-fed plants.

Background And Aims: Soil waterlogging adversely impacts most plants. Melilotus siculus is a waterlogging-tolerant annual forage legume, but data were lacking for the effects of root-zone hypoxia on nodulated plants reliant on N2 fixation. The aim was to compare the waterlogging tolerance and physiology of M.

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

Hordeum marinum Huds. is a waterlogging-tolerant wild relative of wheat (Triticum aestivum L.).

Leaf gas films contribute to rice (Oryza sativa) submergence tolerance during saline floods.

Floods and salinization of agricultural land adversely impact global rice production. We investigated whether gas films on leaves of submerged rice delay salt entry during saline submergence. Two-week-old plants with leaf gas films (+GF) or with gas films experimentally removed (-GF) were submerged in artificial floodwater with 0 or 50 mm NaCl for up to 16 d.

A major locus involved in the formation of the radial oxygen loss barrier in adventitious roots of teosinte Zea nicaraguensis is located on the short-arm of chromosome 3.

A radial oxygen loss (ROL) barrier in roots of waterlogging-tolerant plants promotes oxygen movement via aerenchyma to the root tip, and impedes soil phytotoxin entry. The molecular mechanism and genetic regulation of ROL barrier formation are largely unknown. Zea nicaraguensis, a waterlogging-tolerant wild relative of maize (Zea mays ssp.

Energetics of acclimation to NaCl by submerged, anoxic rice seedlings.

Background And Aims: Our aim was to elucidate how plant tissues under a severe energy crisis cope with imposition of high NaCl, which greatly increases ion fluxes and hence energy demands. The energy requirements for ion regulation during combined salinity and anoxia were assessed to gain insights into ion transport processes in the anoxia-tolerant coleoptile of rice.

Methods: We studied the combined effects of anoxia plus 50 or 100 mm NaCl on tissue ions and growth of submerged rice (Oryza sativa) seedlings.

Tissue-specific root ion profiling reveals essential roles of the CAX and ACA calcium transport systems in response to hypoxia in Arabidopsis.

Waterlogging is a major abiotic stress that limits the growth of plants. The crucial role of Ca(2+) as a second messenger in response to abiotic and biotic stimuli has been widely recognized in plants. However, the physiological and molecular mechanisms of Ca(2+) distribution within specific cell types in different root zones under hypoxia is poorly understood.

Salt sensitivity in chickpea: Growth, photosynthesis, seed yield components and tissue ion regulation in contrasting genotypes.

Chickpea is a relatively salt sensitive species but shows genotypic variation for salt tolerance, measured as grain yield per plant in mild-to-moderately saline soil. This experiment was designed to evaluate some physiological responses to salinity in three contrasting genotypes. One tolerant (Genesis836), one moderately tolerant (JG11) and one sensitive (Rupali) genotype were grown for 108d in non-saline nutrient solution (controls) and two levels of salinity treatment (30 and 60mM NaCl).

Visualisation by high resolution synchrotron X-ray phase contrast micro-tomography of gas films on submerged superhydrophobic leaves.

Floods can completely submerge terrestrial plants but some wetland species can sustain O2 and CO2 exchange with the environment via gas films forming on superhydrophobic leaf surfaces. We used high resolution synchrotron X-ray phase contrast micro-tomography in a novel approach to visualise gas films on submerged leaves of common cordgrass (Spartina anglica). 3D tomograms enabled a hitherto unmatched level of detail regarding the micro-topography of leaf gas films.

Linking oxygen availability with membrane potential maintenance and K+ retention of barley roots: implications for waterlogging stress tolerance.

Oxygen deprivation is a key determinant of root growth and functioning under waterlogging. In this work, changes in net K(+) flux and membrane potential (MP) of root cells were measured from elongation and mature zones of two barley varieties under hypoxia and anoxia conditions in the medium, and as influenced by ability to transport O2 from the shoot. We show that O2 deprivation results in an immediate K(+) loss from roots, in a tissue- and time-specific manner, affecting root K(+) homeostasis.

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.

Leaf gas films delay salt entry and enhance underwater photosynthesis and internal aeration of Melilotus siculus submerged in saline water.

A combination of flooding and salinity is detrimental to most plants. We studied tolerance of complete submergence in saline water for Melilotus siculus, an annual legume with superhydrophobic leaf surfaces that retain gas films when under water. M.

Tolerance of submerged germinating rice to 50-200 mM NaCl in aerated solution.

This paper concerns tolerance to 50-200 mM NaCl of submerged rice (Oryza sativa cv. Amaroo) during germination and the first 138-186 h of development in aerated solution. Rice was able to germinate and the seedlings even tolerated exposure to 200 mM NaCl, albeit with severe growth restrictions.

Shoot atmospheric contact is of little importance to aeration of deeper portions of the wetland plant Meionectes brownii; submerged organs mainly acquire O2 from the water column or produce it endogenously in underwater photosynthesis.

Partial shoot submergence is considered less stressful than complete submergence of plants, as aerial contact allows gas exchange with the atmosphere. In situ microelectrode studies of the wetland plant Meionectes brownii showed that O(2) dynamics in the submerged stems and aquatic roots of partially submerged plants were similar to those of completely submerged plants, with internal O(2) concentrations in both organs dropping to less than 5 kPa by dawn regardless of submergence level. The anatomy at the nodes and the relationship between tissue porosity and rates of O(2) diffusion through stems were studied.