Plant bacteria breakthrough enables crops worldwide to take nitrogen from the air

"N-Fix" can replace expensive and environmentally damaging nitrate fertilizers
August 1, 2013
Dr Philip Stone from The University of Nottingham tending to the plants undergoing the atmospheric nitrogen fixation trials

Dr Philip Stone from The University of Nottingham tending to the plants undergoing the atmospheric nitrogen fixation trials (credit: The University of Nottingham)

The University of Nottingham scientists have developed a new technology that would enable all of the world’s crops to take nitrogen from the air, instead of requiring expensive and environmentally damaging fertilizers.

Nitrogen fixation, the process by which nitrogen is converted to ammonia, is vital for plants to survive and grow. However, only a very small number of plants, most notably legumes (such as peas, beans and lentils) have the ability to fix (use) nitrogen from the atmosphere, with the help of nitrogen fixing bacteria.

The vast majority of plants have to obtain nitrogen from the soil, and for most crops currently being grown across the world, this also means reliance on synthetic nitrogen fertilizer.

Adding nitrogen-fixing bacteria to roots

Professor Edward Cocking, Director of The University of Nottingham’s Centre for Crop Nitrogen Fixation, has developed a unique method of putting nitrogen-fixing bacteria into the cells of plant roots.

His major breakthrough came when he found a specific strain of nitrogen-fixing bacteria in sugar cane known as G. diazotrophicus could intracellularly colonize all major crop plants.

This ground-breaking development potentially provides every cell in the plant with the ability to fix atmospheric nitrogen. The implications for agriculture are enormous, as this new technology can provide much of the plant’s nitrogen needs, he suggests.

Section of root tip after inoculating with G. diazotrophicus, showing extensive intracellular colonization. Scale bar: 10 microns. (Credit: The University of Nottingham)

Known as N-Fix, the  method is neither genetic modification nor bioengineering. It is based on naturally occurring nitrogen fixing bacteria that take up and use nitrogen from the air.

Applied to the cells of plants via the seed, it provides every cell in the plant with the ability to fix nitrogen. Plant seeds are coated with these bacteria to create a symbiotic, mutually beneficial relationship and naturally produce nitrogen.

N-Fix is a natural nitrogen seed coating that provides a sustainable solution to fertilizer overuse and nitrogen pollution. It is environmentally friendly and can be applied to all crops.

Over the last 10 years, The University of Nottingham has conducted a series of extensive research programs which have established proof of principle the technology in the laboratory, growth rooms and glasshouses.

Nitrate pollution

A leading world expert in nitrogen and plant science, Professor Cocking has long recognized that there is a critical need to reduce nitrogen pollution caused by nitrogen based fertilizers. Nitrate pollution is a major problem as is also the pollution of the atmosphere by ammonia and oxides of nitrogen.

In addition, nitrate pollution is a health hazard and also causes oxygen-depleted “dead zones” in our waterways and oceans. A recent study estimates that that the annual cost of damage caused by nitrogen pollution across Europe is £60 billion to £280 billion.

Professor Cocking said: “Helping plants to naturally obtain the nitrogen they need is a key aspect of world food security.

“The world needs to unhook itself from its ever increasing reliance on synthetic nitrogen fertilizers produced from fossil fuels with its high economic costs, its pollution of the environment and its high energy costs.”

Making N-Fix available worldwide

Professor Ted Cocking from University of Nottingham with a plant grown using nitrogen fixation N Fix technology

Professor Ted Cocking from University of Nottingham with a plant grown using nitrogen fixation N Fix technology (credit: University of Nottingham)

The N-Fix technology has been licensed by The University of Nottingham to Azotic Technologies Ltd to develop and commercialise N-Fix globally on its behalf for all crop species.

Peter Blezard, CEO of Azotic Technologies added: “Agriculture has to change and N-Fix can make a real and positive contribution to that change.

It has enormous potential to help feed more people in many of the poorer parts of the world, while at the same time, dramatically reducing the amount of synthetic nitrogen produced in the world.”

Azotic is now working on field trials to produce robust efficacy data. This will be followed by seeking regulatory approval for N-Fix initially in the UK, Europe, USA, Canada and Brazil, with more countries to follow. It is anticipated that the N-Fix technology will be commercially available within the next two to three years.

The University of Nottingham’s Plant and Crop Sciences Division is internationally acclaimed as a centre for fundamental and applied research, underpinning its understanding of agriculture, food production and quality, and the natural environment.  It also has one of the largest communities of plant scientists in the UK.

Abstract of “Intracellular colonization of roots of Arabidopsis and crop plants by Gluconacetobacter diazotrophicus” paper

We have investigated the interaction of Gluconacetobacter diazotrophicus, a non-nodulating endophytic nitrogen-fixing bacterium isolated from the intercellular spaces of sugarcane, with Arabidopsis thaliana and the crop plants maize (Zea mays), rice (Oryza sativa), wheat (Triticum aestivum), oilseed rape (Brassica napus), tomato (Lycopersicon esculentum), and white clover (Trifolium repens). Using seedlings grown aseptically in sucrose-containing culture media, we have shown that inoculation with very low numbers of G. diazotrophicus results in extensive intracellular colonization of root meristems and progressive systemic intracellular root colonization. Light microscopic examination of thin sections of resin-embedded root tips of Arabidopsis and these crop plants inoculated with β-glucuronidase (GUS)-labeled and with NifH promoter-GUS-labeled G. diazotrophicus showed blue-stained G. diazotrophicus within the cytoplasm of root cells, indicating that intracellular conditions were suitable for nitrogenase gene expression. Electron microscopy confirmed that these bluestained intracellular G. diazotrophicus were within membrane-bounded vesicles. We discuss whether these novel inoculations with G. diazotrophicus are likely to enable non-nodular endosymbiotic nitrogen fixation and whether these inoculations can also provide a plant system to investigate the endosymbiotic theory of the origin of eukaryotic organelles.