Project Highlight – GlnLux

A Canadian invention may help farmers optimize legumes for protein content and organic fertilizer production

A University of Guelph biotech invention supported financially by a DFATD/IDRC-CIFSRF grant may help alleviate dietary protein deficiencies, improve farmer livelihoods while simultaneously helping to reduce the need for synthetic nitrogen fertilizer. Globally, subsistence farmers suffer from protein (amino acid) deficiencies, especially women and children eating a starch rich diet. Legumes such as lentils, cowpea, and common beans are excellent sources of complete protein, because they have the potential to synthesize the limiting building block, nitrogen, specifically ammonia. In non-legume crops such as corn, farmers add ammonia in the form of synthetic nitrogen fertilizer. Synthetic nitrogen fertilizer has been a transformative additive, but it can be very expensive for subsistence farmers to purchase, and it consumes natural gas in its synthesis and hence contributes to climate change.
Legume plants solve the nitrogen fertilizer problem by naturally associating with symbiotic microbes known as rhizobia in their roots. Rhizobia capture nitrogen gas, which is abundant in the atmosphere, and convert it into ammonia, which legumes then use to make protein in the grain — as well as rich organic nitrogen in the leaves for use as mulch to feed cereal crops such as corn, wheat and rice. This symbiotic process is called biological nitrogen fixation (BNF). Rhizobia are the ultimate probiotics of agriculture. Cereal crops do not form these symbiotic microbial associations in their roots and hence require external nitrogen fertilizer.

Unfortunately for BNF to occur, legumes require compatible microbial partners – which are sometimes not naturally found in local soils, especially if a crop or crop cultivar was recently introduced. Legumes that are grown in soils with sub-optimal microbes suffer from lower yields and a lower protein nutritional content. To solve these problems, post doctoral fellow Dr. Malinda Thilakarathna, working in the laboratory of Prof. Manish Raizada at the University of Guelph, has pioneered a biosensor technology called GlnLux (pronounced glutamine-lux) using funding from the CIFSRF program. Glutamine is a key product of symbiotic microbial BNF in legumes. In the first year of funding, Dr. Thilakarathna, with assistance from undergraduate Caleb Niemeyer, has demonstrated that when legume seedlings, including lentil, alfalfa and common beans, are exposed to compatible rhizobia in their roots, the biosensor emits light – when these plants are placed onto the biosensor in the lab. Furthermore, all that is required for the technology to work is removing a 1-cm diameter leaf punch, then adding it to the biosensor detector (luminometer). The cost of this diagnostic technology is $1 per sample, compared to traditional testing for BNF at $10-$20 per sample.  This low cost paves the way for the technology to be used not only in Canada but in developing nations.

The objective of the GlnLux technology is to help researchers working with farmers to discover the most compatible and/or optimal rhizobia microbes and other practices that maximize BNF and legume yields. Around the world, farmers already purchase rhizobia and coat them onto seeds, including Canadian soybean farmers, but rhizobia – an inexpensive, environmentally friendly and organic technology — is not in the hands of many subsistence farmers.

A longer-term objective of GlnLux is to provide scientists with a new tool to breed legume crops to withstand climate change – since during drought, BNF fails. Along these lines, in the first year of funding from IDRC, Dr. Thilakarathna has gained evidence that the technology can distinguish between beans that differ in their capacity to facilitate BNF. The latter project is a collaboration with Prof. Ali Navabi, also at the University of Guelph.

The GlnLux technology is now being transferred to an NGO partner in Nepal (LI-BIRD) as well as the Nepal Agricultural Research Council (NARC) – and it is hoped that the technology will stimulate both the Canadian and Nepalese private sectors to optimize rhizobia microbes (as well as other practices) that improve the livelihoods of local legume farmers. The project has already succeeded in demonstrating that the technology can be used in the laboratory with Nepalese varieties of 3 different legumes, with additional legumes currently being tested. In the coming 24 months, the technology will be tested in field trials with test farmers, under real world conditions, to determine if it can help local farmers assess the benefits of coating seeds with rhizobia by comparative measurements of yield, protein/nitrogen content and traditional BNF diagnostics.

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