What Endophytes Reveal about GMOs

Figure 1.  Endophytic microbes like these blue staining fungi found in micropropagated plants raise new concerns for GMO safety.

Those who favor GMO’s claim engineered organisms confer benefits that improve nutrition or reduce the need for pesticides.  They downplay reports of containment issues, claiming such reports have not been scientifically validated.

GMO opponents argue that chemical use often increases when GMO’s are introduced (this is clearly intuitive in the case of plants that have been engineered to tolerate herbicides), that engineered genes are difficult to contain in the environment, that pests, weeds, and other organisms GMO’s were designed to combat quickly develop tolerances to the engineered genes, and that long term human health effects of GMO foods have not been adequately tested.

Prepare for a whole new wave of data to enter the debate.

In 2010, we published a manuscript illustrating the presence of more than two dozen species of endophytic microbe that reside within micropropagated plants.  A feature of this peer reviewed study that left a deep impression on me was the fact that each time we modified our PCR primers (think of these as the baited fish hooks used to pull specific genes out of an ocean of DNA), we found new species.  We were not the first to report endophytes in micropropagated plants.  We were perhaps the first to report such complexity in the microbial community.  There is good reason to believe that all plants have similar associations.  Atsatt and Whiteside have reported features of plant associated fungi that make them particularly difficult to detect and separate from plant cells.

The presence of microbial communities endogenous to micropropagated plants raises questions about the safety and containment of engineered genes.  Among these:  If cryptic communities of diverse fungi and bacteria reside in plants when new genes are inserted, what controls have been implemented to exclude the engineered genes from microbial genomes?  (Answer:  none.  Standard and approved genetic engineering protocols have been developed under the assumption that micropropagated plants are axenic, or free of contaminating microbes).  Now, let’s assume for a moment that an engineered gene was inadvertently inserted into an endophytic fungus, that is capable of existing either as an endophyte or as a soil fungi (an Alternaria, for example). What is to keep this fungus (the genera is typically found in diverse habitats) from transferring to other host plants, propagating patented genes throughout the environment?

The growing recognition of microbiomes (microbial communities that associate with all living systems) as drivers of good health and nutrition raises perhaps a more important question about the utility of GMO’s.  What do we take away from the plant in the process of adding one or a few new genes?   The images below represent plants with (a) and without (b) a complete, properly structured microbiome. While a micropropagated plant may contain dozens of microbial species living in and around its cells, a plant growing in a healthy soil may contain hundreds of thousands of associated microbes.

Figure 2.  Originally published in Sustainable agroecosystems in climate change mitigation, this image summarizes the nutrient cycling and plant protection features offered by a diverse and properly structured microbiome.  Plants that have been stripped of their microbial diversity are nutrient deficient, intolerant of climatic extremes, and prone to pests and disease.

When seeds are germinated to produce plants in-vitro (in sterile containers like test tubes) prior to engineering, they must be surface disinfested to remove those microbes which might grow quickly in test-tubes and compete with the plant for nutrients. In the laboratory, plants are typically disinfested with bleach, alcohols, or other antiseptic agents and maintained in an aspetic environment. Then they are exposed to growth regulators, chemically defined growth media, and artificial light.  Many microbial species present on and in the plant when it is exposed to these treatments are permanently eliminated.   Each microbe may have thousands of genes, and some of these have co-evolved with the host plant.  Removing these microbes in order to insert a single gene may produce germplasms that can be patented and sold for a premium price, and indeed, with the exception of the inserted gene, these plants are not being treated differently from many transplants that are generated for large farms today.  But the fact is, plants raised in vitro, with or without being subjected to genetic engineering, are plants that have been stripped of rich microbial communities containing entire metagenomes (millions to billions of genes) that empower native plants in natural habitats to withstand environmental assault. Such plants will always require more inputs to sustain them than plants whose microbiomes have been preserved.

At End-O-Fite Enterprises LLC, we are working with large and small growers to restore microbiomes to crops and soils.  Growers utilizing our protocols are seeing input costs decline and profits increase, since they obtain similar or higher yields, and receive higher premiums for the resulting organic crops.  Other consultants are reporting similar results.

In conclusion, GMO safety is heavily debated because many aspects of GMO safety have simply not been considered by regulatory authorities.  Breakthroughs in metagenomics and endophyte ecology are revealing new dynamics that suggest GMO’s cannot be contained, and possibly do more to reduce plant productivity than to increase it.  As news of the improved yields attainable in bioactive soils spreads, is my personal belief that farming practices rooted in microbial ecology and soil biology will soon make GMO’s and the debates surrounding their safety obsolete.