Plant Sciences

 

- Plant Stress Factors -

 

Drought, extreme temperatures, chemical pollutants, salinity, pests, disease, and waterlogging are a few adverse factors affecting a plants ability to optimally function. Using NMT, scientists now have the ability to research how plants regulate flux activities of specific ions and molecules.

 

Specific Areas of Study:

• Plant response to stress conditions
• Physiological regulation mechanisms of signal transduction pathways
• Screening of the stress-resistant varieties of crops

 

Examples:

(1) NMT reveals the mechanism causing one plant species to have a higher salt resistance than another. 

 

Sun J, et al. Plant Physiology, 2009, 149: 1141-1153

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(2) NMT directly measured the PM H⁺-ATPase activities via the H⁺ flux.

Yang YQ, et al. Plant Cell, 2010, 22: 1313 - 1332.

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- Photosynthesis and Respiration in Plants -

 

Cellular homeostasis, and thus cellular health and longevity, rely on the efficient exchange between ions/molecules and the external environment. Factors including leaf morphology, mesophyll cell growth and light intensity all directly impact the capability of photosynthesis.

 

Plants respire by consuming O₂ then producing energy in the form of glucose. This energy is stored by maintaining a proton (H⁺) gradient across the plasma membrane. Therefore, being able to measure ionic/molecular flux directly, non-invasively, in situ, in vivo, and in real time makes NMT an ideal tool to study both photosynthesis and respiration in plants.

 

Specific Areas of Study:

• Mechanism of Photosynthesis
• Mechanism of Respiration in Plants
• Screening of Plants with High Photosynthesis Efficiency

 

Examples:

(1) Using NMT, extracellular oxygen and proton fluxes from Spirogyra grevilleana were measured. When the cell was illuminated, oxygen showed a net efflux and protons showed a net influx . These measurements provided a new insight in our understanding of basic cellular physiology in plant photosynthesis.

PorterfieldDM and Smith PJS. Protoplasma, 2000, 212: 80-88

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(2) Using NMT, extracellular oxygen and proton fluxes from pollen tube were measured. O₂ influxes and H⁺ effluxes were detected in the region of condensed mitochondria.

Xu Y, et al. Journal of integrative plant biology, 2006, 48: 823-831.

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- Development and its Regulations -

 

Plant growth and development is a complex process, accompanied by active metabolism and exchanges of various substances with the outside world. It starts from seed germination, root, leaf differentiations, growth and maturation, flowering, reproduction, and finally aging and death. Therefore, detection of fluxes of H⁺, Ca²⁺, K⁺, Cl^-, Mg^2 +, and O₂ provides an indispensable way to understand the plant growth and development and how they are regulated.

 

Specific Areas of Study:

• Study the mechanisms of regulation of plant development
• Study the roles of auxin, gibberellin, abscisic acid, ethylene and other plant hormones
• Study stress phenomena in plant development
• Signal transduction
• Looking for mechanisms to promote the rapid growth and development of crops

 

Examples:

(1) Ca²⁺ influxes were affected by NO stimulator or suppressor

Wang Yuhua, et al. New Phytologist, 2009, 182: 851-862.

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(2) Cl^- fluxes are correlated with pollen tube growth

Laura Zonia, et al. Plant Cell, 2002, 14: 2233-2249

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- Microbial Interactions -

 

To study the interactions between microbes and plants, microbes and microbes, and microbes and other organisms it is crucial to understand symbiotic, antagonistic and parasitic relationships. Since most of the interactions are mediated by activities of various ions and molecules, NMT, which can non-invasively detect minute dynamic fluxes of these ions/molecules in real time, is an innovative tool to uncover these interaction processes.

 

Specific Areas of Study:

• Mechanism of plant and microbial interactions
• Plant signal transduction in fungal infection process
• Plant mycorrhizal study
• Plant nitrogen fixation
• Allelopathy
• Fungal development

 

Examples:

(1) Characteristics of H⁺ fluxes during fungal development, and are subject to the regulation of nutrient absorption

Ramos AC,et al. New Phytologist, 2008, 178: 177-188.

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(2) Ca²⁺effluxes present after infected by P. syringae pv syringae

 

Nemchinov LG, et al. Plant Cell and Physiology, 2008, 49: 40-46.

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- Signal Transductions -

 

Mycorrhizal is a typical host plant - fungal symbiotic interactions, plant nutrient uptake and growth are accelerated by fungal infection, which is also dependent on the pH.

 

Example:

Ramos AC, et al. New Phytologist, 2009, 181: 448-462.

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- Plant Nutrition -

 

In order to survive and grow, plants need a large number of Nitrogen, Phosphorous, Potassium, and other nutrients from the environment. These nutrients are often in the forms of NH₄⁺, of NO₃^-, K,⁺ influxes near the surface of the roots. Meanwhile, fluxes of other ions and/or molecules, such as Ca^2 +, H⁺, and O₂ are also important to regulate the nutrient's absorption process.

 

NMT is a vital tool to study plant nutrition absorption and regulation mechanisms because not only can it measure NH₄⁺, NO₃^-, of K⁺, Ca^2 + , O₂, and H⁺ but it also provides a way to study them in-situ, in vivo, in real time, and theoretically no restrictions to the size of your samples.

 

Specific Areas of Study:

• Mechanism of crop nutrient absorption
• Looking for substances that can regulate nutrient absorption
• Screening crops
• Evaluation of the effect of fertilizer
• Develop guidance of rational fertilization process

 

Examples:

(1) Periodical oscillations of H⁺, K⁺ and Ca²⁺ absorptions have been found in the roots of wheat

ShabalaS, et al. Functional Plant Biology, 2002, 29, 595–605.

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(2) NH₄⁺ and NO₃^- absorptions are regulated by pH

Garnett TP, et al. Plant and Soil, 2001, 236: 55–62.

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(3) Different effects on NO₃^- and NH₄⁺absorptions by increase of external on NO₃^- and NH₄⁺

Fang YY, et al. Annals of Botany, 2007, 99: 365–370.

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Environmental Science

 

- Bio-Monitoring of Environmental Pollutions -

 

Oxygen and Hydrogen activities are essential to all organisms, while aquatic organisms seem to be more sensitive than others in response to environmental changes. They are especially sensitive to pollutants making O₂ and H⁺ fluxes good and reliable indicators of environmental pollutions.

 

It can be applied to water quality assessment and biological early warning of environmental pollutions.

 

Specific Areas of Study:

• Water pollution detection
• Biological early warning
• Water Quality Assessment
• Detection of heavy metal pollution

 

Example:

O₂ flux changes of fathead embryo in response to different pollutants

 

Sanchez BC, et al. Environ. Sci. Technol. 2008, 42: 7010-7017.

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- Heavy metal pollution and treatments -

 

Some organisms, especially some plants, have developed a mechanism for heavy metal tolerance, by which heavy metals (such as of Cd²⁺) enrich their organelles, which provides the possibility for the bioremediation of heavy metal pollution.

 

Most of the animals, however, are very sensitive to the presence of heavy metals, which cause significant changes to their respiration processes. Therefore, NMT, which can directly measure Cd²⁺, H⁺, and O₂ with living samples, is an ideal tool to study the mechanisms of heavy metal absorption and regulations.

 

Specific Areas of Study:

• Heavy metal pollution monitoring
• Heavy metal enrichment mechanism
• Heavy metal pollution control
• Plant heavy metal tolerance mechanism
• Screening of heavy metals is highly efficient in order to enrich plant varieties

 

Examples:

(1) The intestinal and Malpighi tube play an important role in the chironomid larvae Cd²⁺ transport and absorption process

Leonard EM,et al. Aquatic Toxicology. 2009, 92: 179-186.

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(2) Pattern of Cd²⁺ enrichment in wheat roots

Piñeros MA,et al. Plant Physiology. 1998, 116:1393–1401.

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- Bio-Green-Energy -

 

NMT is sensitive enough to measure oxygen fluxes around single cells. In the following example, Porterfield and Smith et al. have characterized oxygen and proton fluxes from a single cell of the filamentous green alga Spirogyra gre illeana (Hass.). 

 

Results showed that oxygen had a net efflux and protons showed a net influx when the cell was illuminated. These photosynthesis-dependent fluxes were found to be spatially associated with the chloroplasts and were sensitive to treatment with dichlorophenyl dimethylurea. In the dark the directions of oxygen and proton fluxes were reversed. This oxygen influx was associated with mitochondrial respiration and was reduced by 78% when the cells were treated with 0.5 mM KCN. The residual cyanide-resistant respiration was inhibited by the application of 5 mM salicylhydroxamic acid, an inhibitor of the alternative oxidase. Similarly the cytochrome pathway was also inhibited by the presence of 20 uM NO, while the cyanide-resistant alternative oxidase was not.

 

These results demonstrate the use of the NMT system to measure and characterize metabolic fluxes at a level of sensitivity that allows for subcellular resolution. 

 

 

Example:

Single-cell, real-time measurements of extracellular oxygen and proton fluxes from Spirogyra grevilleana

Porterfield DM and Smith PJS.Protoplasma, 2000, 212: 80-88

Microbiology

 

- Bio-waste Treatment -

 

The major aim of wastewater treatment is to remove as much of the suspended solids as possible before the remaining water, called effluent, is discharged back to the environment. As solid material decays, it uses up oxygen, which is needed by the plants and animals living in the water. "Primary treatment" removes nitrate, ammonium, heavy metals and other contaminants. Using NMT we were able to see the effect of detoxicity and denitrification by the NO₃^-, NH₄⁺, and O₂ fluxes.

 

Specific Areas of Study:

• Detect ability of uptake to nitrate and ammonium in biofilm
• Evaluate the results of waste water treatment
• Screen and find bacteria or microbe for waste treatment
• Ensure safety standards are met

 

Example:

Non-invasive detect biofilm analyte flux

 

McLamore ES, et al. Biotechnology and Bioengineering, 2009, 102(3):791-799.

 

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- Microbiology & Food Safety -

 

The ability of certain microbes or yeasts to grow at low ambient pH in the presence of lipophilic weak-acid preservatives inflicts heavy losses on the food and beverage industries. The plasma membrane H⁺-extruding H⁺-ATPase is firmly implicated in the ability of S. cerevisiae to resist intracellular acidification caused by weak organic acids. The effect of long-term benzoic acid exposure on cellular K⁺ of both Z. bailii and S. cerevisiae has been examined as a test of the importance of K⁺ uptake in adaptive growth.          

 

Specific Areas of Study:

• Detect acidification by H⁺ flux and pH in microbes
• Rapidly detect key changes and targets of microbes in food                                

 

Example:

Plasma membrane H⁺ and K⁺ transporters are involved in the weak-acid preservative response of disparate food spoilage yeasts

 

Macpherson N, et al. Microbiology. 2005, 151(6): 1995-2003.

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