Gene drives or gene bombs

September 2016

Photo: Creative Commons

Earlier this year, the latest and most sinister variant of genetic engineering yet, the gene drive, hit the headlines [1].

When artificial DNA is linked to a gene drive in a plant or animal, it will engineer any DNA it pairs up with and create a genetic change which is passed on to 99 percent of the offspring. The GMO version will rapidly become ubiquitous in the population.

Oxitec business

September 2016

Photo: Creative Commons

From its August beginnings as a commercial spin-off from Oxford University's Innovation management subsidiary, 'Oxitec' self-destruct GM mosquitoes have never quite fulfilled early expectations.

Even the rosy vision of an end to major world killers like malaria, and dengue fever didn't manage to sell Oxitec mozzies.

However, Zika virus with its horrific connections to birth defects, provided a much better PR platform to generate the will to spend cash and annihilate mosquitoes at any cost [1].

In the meantime, the rights to Oxford's GM mozzies have been sold into the tender care of US-based Intrexon Corporation, and continue to be mired in controversy.

Glyphosate damages soil

September 2016

Photo: Creative Commons

When crops are sprayed with glyphosate, a large proportion ends up on the soil. The GM plants themselves exude glyphosate through their roots into the soil. Also, any plant debris which ends up in the soil will come complete with accumulated glyphosate.

The discovery that GM cotton plants which generate 'Bt' insecticide suffer from impaired ability to support the vital associations with soil fungi in their roots wasn't anticipated [1]. Increasingly, these same Bt crops are also being genetically engineered to tolerate glyphosate herbicide.

Just how Bt plants adversely influence the fungi in and around their roots is unexplained, but glyphosate's effects are highly predictable: fungi are plants and can be harmed by herbicides such as glyphosate due to the same toxic mechanism which kills the weeds. Indeed, a study by Argentinian scientists on grassland, typically treated with glyphosate in late summer to promote the growth of winter annuals, found reduced fungal spore viability and fungal root-colonisation.

Spotlight on spray drift

September 2016

Photo Creative Commons

While agri-businesses see GMOs as central to their future, the brand-oriented and customer-sensitive ends of the food supply chain do not. Indeed, 79% of Americans voice concerns about GM foods.

Although 51% of Americans express concerns over the number of chemicals and pesticides in their food, all current GM crops are designed to generate or accumulate pesticides, and are firmly embedded in the high-chemical-input monoculture model of agriculture.

Fungi don't like Bt crops

September 2016

Photo Creative Commons

The 'Bt' toxins produced by many commercialised GM crops are based on insecticidal proteins produced by soil bacteria, but have many important differences to the natural substance.

To mention just a few, they're plant proteins with bacterial qualities, or bacterial proteins with plant qualities, depending on your point of view. They're produced in a fully active (toxic) form without the environmental barriers inherent in the natural bacterial versions which need to be exposed to insect gut chemistry to become activated. GM 'Bt' toxins are unnatural in conception, construction, location and action.

Industry marketing has plugged its Bt as an insect-specific toxin which, outside of the pest gut, is just an innocuous protein. Who would have thought it could be harmful to fungi?

Soil fungi are fundamental to soil fertility and plant nutrition. They play key roles in the cycling of nutrients in the soil and supplying them to plants, and in soil water availability.

Such fungi also assist the plant in tolerating pathogens and abiotic stresses.

Most plants have an intimate relationship with specific fungi, which grow around their roots and penetrate into the cells of the root where a mutual exchange of nutrients can proceed.

So what happens when a fungus tries to colonise a GM, Bt-generating, plant?

Healthy soil needs a diversity of life

September 2016

Photo Creative Commons

Today's scientists are cataloguing a staggering number of diverse species living in the soil. Besides the plants, animals, bacteria and fungi there's a host of much smaller microbes and single-cells organisms.

The intriguing picture emerging is of a coherent soil-world in which the diversity of life, especially the microbial forms, prevent, and sometimes cure, diseases. In this subterranean world, pathogens exist but are crowded out by the sheer variety of life around them. Plant roots orchestrate a consortium of friendly microbes around and within themselves. The soil, thus, not only provides a non-specific immune-system for the plants, but also forms an evolving protection against specific pathogens which are remembered in future years if the same pathogen emerges again.

Human efforts to engineer soil immunity by adding 'key' microbes have met with very limited success: the simple, single-pronged attack just isn't stable or comprehensive or intelligent enough.