Crispr – Potentially a very Bright Future in Plant Breeding

Over the last 25 years there have been assortment of genetic modification techniques used in the pursuit of enhancing plant traits. In the early 1990’s we saw the first transformation of tobacco using the tobacco mosaic virus (TMV) coat protein expressed in a binary plasmid vector. This conferred resistance to TMV, the mechanism for which was unconfirmed at the time, but was (incorrectly) assumed to be what was referred to as coat protein mediated resistance (Beachy, R.N. 1999. Coat-protein-mediated resistance to tobacco mosaic virus: discovery mechanisms and exploitation). At the time agrobacterium was used in transforming plants, as too were various iterations of what was referred to as a “gene gun” where plant tissue was bombarded with gold or tungsten particles coated with plasmid vectors containing genes of interest to be expressed in plants, silence genes or invading plant pathogens including viruses. The gold or tungsten particles were literally fired into the cells either by gunpowder (literally as in using a bullet) or a high gas pressure discharge, all in a vacuum chamber (referred to as biolistics).

Since then there has been active research into improving both the technics of transformation as well as understanding gene expression. At the time there was enormous commercial interest in using the technology in improving plant varieties. The earliest commercial example was the Flavr Savr tomato (Martineau B. Gresshoff PM.  From lab bench to market-place: The Calgene FLAVR SAVR tomato: Technology Transfer of Plant Bio-technology 1997. CRC Press). But this is just where the story really starts in the adoption of genetically modified crops, which is opportune for a separate post.

One of the drivers in developing technologies for the commercial release of GM crops has been regulation. Crops modified in the early days, including the original TMV resistant tobacco along with all the biolistic generated lines, would never see the light of day in todays regulatory environment due to numerous requirements (not withstanding cost), the main one being absence of non-targeted DNA such as plasmids, bacteria (used in the multiplication of the plasmid vectors) etc. A such the road to development was either theoretical, in University or research institute labs with no commercial release, or the domain of large multinational agribusinesses including Monsanto (Bayer) which has dominated this space over the last 20 years.

Now there is the opportunity for a change in the “genetic modification space” with the development of the CRISPR/Cas9. CRISPR is another of the genome editing, site-specific nucleases that has seen enormous adoption over the last five years. Its potential lies in its high degree of specificity in not just adding targeted genes but also in inferring loss of function or gene silencing. However, its main attraction lies in its potential to avoid the need for regulation, which has garnered the interest of many not just as a research tool but its potential for commercial application. It is likely that we will see the USDA-APHIS announcing in the near future that use of CRISPR/Cas9 falls outside the regulatory environment provided that no foreign DNA nor expression vectors are contained. This is on the heals of a ruling by the USDA-APHIS on the acceptance of CRISPR-edited mushroom as not being a regulated article and submissions from numerous organisations requesting similar rulings on their CRISPR-edited crops ( All-in-all, the potential for widespread adoption of the technology for commercial application is very promising. The downside is that outside the USA adoption is likely to be slow, especially in Europe where resistance to the use of gene-editing tools in food products has yet to be overcome.

Regardless, CRISPR has definitely invigorated the plant breeding community.

Update on licensing: There have been some misleading reports in the press that Bayer has been granted exclusive rights by ERS for the use of CRISPR/Cas9. It would appear that some news sources have looked at the first paragraph of major news outlets without looking further down at the details, being that it is only for human therapeutics to cure blood disorders, blindness, and congenital heart disease (see official Bayer press release for the details). For the details relating to the exclusivity and non-exclusivity licencing go to the Broad Institute’s website where they clarify the distinction of exclusive rights in the case of human therapeutics.

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