New GM insecticide

December 2016

Photo: Creative Commons

Scientists at biotech company, DuPont Pioneer, have been busy searching around in the soils of America for an alternative to 'Bt' insecticides. These pest-killing proteins, whose ancestors came from Bacillus thuringiensis soil bacteria, have proved a marvellous money-spinner for two decades. Now, pest resistance to Bt toxins is rising, and even the new generations of GM crops with stacked Bt variants look like having a limited shelf-life.

DuPont has its fingers crossed that it's found a solution. Its scientists have found a previously uncharacterised protein, designated 'IPD072Aa', which just might serve its purpose.

IPD072Aa was extracted from soil bacterium Pseudomonas chlororaphis*, so perhaps Bt strains and toxins in our diet will be replaced by 'Pc' strains and toxins?

*Note. Pseudomonas chlororaphis isn't a new discovery. It generates an enzyme used in industrial acrylamide production to make industrial materials, for example, adhesives, coagulants, paints, paper, and soil amendments. 

The new gene has already been inserted into maize where it gave excellent root protection from Western corn rootworm compared to an identified control.

'Pc' is a small protein. It has much less scope for the plasticity which makes the much larger Bt-protiens able to evolve into new toxins. While Bt can poison a wider range of animals, Pc gives very selective control against a single pest.

OUR COMMENT 

Unlike B. thuringiensis (the source of Bt toxins) P. chlororaphis (source IPD072Aa) of is an opportunistic human pathogen. The E.coli bacteria which both toxin-generating genes were cloned in before being popped into maize has definitely human pathogenic potential. Let's hope 'Pc' protein is very thoroughly tested for human safety before anyone tries to put it into our food chain. 

Time will tell how viable Pc-protected GM crops turn out to be. The early biotech assumption that, because bacteria and insects had co-existed and evolved together for millions of years, the pests wouldn't develop resistance has rapidly proved naïve. 'Pc', as a smaller and less variable toxin, may stimulate pest-resistance even faster. 

Just think how all that money spent on 'Pc' crops could be better used for sustainable human good. 

SOURCES

• Ute Schellenberger, et al., 2016, A selective insecticidal protein from Pseudomonas for controlling corn rootworms, Science Magazine 
• Diego Faccone, et al., 2014, Human infections due to Pseudomonas chlororaphis and Pseudomonas oleovorans harboring new BLAVIM-2-borne integrons, Letter to the Editor, Infection, Genetics and Evolution 28 
• Mohamed A. Ibrahim, et al., 2010, Bacillus thuringiensis, A genomics and proteomics perspective, Landis Bioscience Jan/Feb 
• Dan Charles, As a GMO pillar wobbles, biotech companies promise new insect-killing genes, www.npr.org, 22.09.16