Metallic rice

February 2017

Global mapping shows an "unequivocal overlap" of poverty, micronutrient deficiency and rice consumption.

Estimates suggest some 15% of the world's population suffer from iron-deficiency anaemia, and a similar number from zinc-deficiency. These have serious consequences for health and energy, immune- and nervous-system function, gene regulation and child development, and for productivity.

Part of the problem is that rice doesn't have enough iron and zinc in it for people with little else to eat. From the biotech scientist's point of view, this is the rice's fault. The answer is therefore to insert artificial genes which drive an unnatural accumulation of iron and zinc in the rice plants.

University of Melbourne researchers have come up with the perfect GM micronutrient-deficiency cure: transgenic rice plants able to store iron and zinc at concentrations higher than the 30% of 'estimated average requirement' specified by nutritionists.

Very much to their credit, the scientists took the time and trouble to make sure their iron- and zinc-fortified rice didn't suffer from the many problems which have dogged previous such GM offerings. Indeed, they screened 1,689 genetic transformation events involving seven different artificial DNA constructs to achieve the optimum GM biofortified rice.

Their novel rice is a variety popular in countries at which it will be targeted. It exhibits no yield loss due to the extra artificial protein production, and accumulates iron and zinc as well in the field as it does in the greenhouse.

To optimise the GM rice for regulatory assessments, the novel proteins have been limited to two plus an anti-biotic resistance marker gene already widely approved in GM crops around the world (although the antibiotic is still used for livestock). One of the novel genes is copied from rice and the other from soya: both, therefore, code for plant proteins with a long history of safe consumption and use.

They made sure their DNA construct hasn't inserted inside a gene, hasn't acquired spurious extra DNA fragments or rearrangements, and that it remained stable during the breeding process.

A simulated digestion of the GM rice fed to a cell culture model of the human digestive system indicated that the iron and zinc would be readily absorbed.

Since the mechanism for uptake of iron and zinc in plants can potentially be hijacked by other metals in the soil, the absence of toxic metal accumulation in the GM rice was ascertained in the field and in the lab.

Rice naturally takes up its iron and zinc requirements from the soil, but humans need a lot more in their diet than this crop can supply, especially since only some 10% of the plant-based iron and 25% of plant-based zinc is absorbed. The GM rice has double copies of two genes which boost levels of two kinds of carrier proteins for iron and zinc. Natural genes with these functions are only expressed when the plant is short of these micro-nutrients, but the artificial ones are switched on all the time to suck the metals out of the soil.

The team spokesman said "There are no deal-breakers in these results. We have proven our concept in a major variety of rice, and we are now ready to move this into a developing country".

That 'developing country' is, it seems, Bangladesh which has a notoriously weak regulatory system and an administration already determined to push GM (pest-resistant) aubergines into its fields and markets [1].

OUR COMMENT

There may be fewer deal breakers in this GM rice, but no deal breakers is a touch simplistic. For example ...
 
Some 30% of the world's soils are zinc-deficient. Our Green Revolution with its high-yielding crops, fertilizers and pesticides, paid scant attention to the micronutrients also needed for both plant and consumer health: as a result, many crops, may have been inadvertently bred to tolerate low zinc availability. GM plants primed to further drain zinc from the soil may make a bad situation worse.
 
Some metals, in the right place, time and quantity are essential nutrients while some can become toxic. All are highly reactive, and interact and compete, not only with each other, but with many other substances and conditions in the soil, in the plant and in the animal consumer. Knock-on and possibly harmful effects of crops which can't switch off their absorption of metals need extensive clarification.
 
There were no toxicologists or nutritionists on the team, and apparently no thoughts of clinical trials, nor of applying the sort of biochemical profiling which is already revealing potentially harmful changes in GM harvests [2]. There was no recognition of the reality that impoverished, rice-dependent people also lack access to fresh produce with the vitamin C vital for good iron absorption. No mention was made of a need to monitor high-risk groups, such as women of child-bearing age and the under-fives for unpredicted adverse effects of the GM rice, nor for the realty of assumed health outcomes.
 
Bacterial and fungal pathogens need iron and zinc too. A poorly controlled abundance of these metals in the plants could feed disease. Conversely, plants use iron redistribution to protect themselves from pathogens: this immune-system reaction could be catastrophically impaired by the uncontrolled artificial genes that force iron-uptake in GM plants.
 
One of the novel genes is driven by a Cauliflower Mosaic Virus (CaMV) promoter. This DNA on-switch is active in most organisms and has long been recognised as a likely source of unexpected gene expression and instability in the genome [3].
 
The research had funding from the Gates Foundation, and where Gates is, PR is never far behind. In their concluding remarks, the authors say "This achievement enables the future option to combine Fe (iron), Zn (zinc) and provitamin A traits in rice grain." Ah, golden rice with metal bits is on the menu, and there are definitely deal-breakers there [4].

Background:

[1] CULTIVATING PR - December 2015

[2] NK603 MAIZE IS NOT EQUIVALENT - January 2017

[3] VIRAL DNA DANGERS - GMFS Archive, June 2009

[4] YELLOW RICE NOT NICE - October 2016


SOURCES
  • GM iron and zinc biofortified rice not adequately tested for safety, GM Watch, 18.11.16
  • Andrew Trounson, Improving half the world's diet, University of Melbourne, https://pursuit.unimelb.edu.au
  • Kurniawan R. Trijatmiko, et al., 2016, Biofortified indica rice attains iron and zinc nutrition dietary targets in the field, Nature Scientific Reports
  • Guillaume Debeaux, et al., 2015, Getting to the root of plant iron uptake and cell-cell transport: polarity matters!, Communicative and Integrative Biology
  • David L. Greenshields, et al., 2007, Roles of Iron in Plant Defence and Fungal Virulence, Plant Signalling & Behaviour, 2:4
  • M. Indriati Hood and Eric P. Skaar, 2012, Nutritional immunity: transition metals at the pathogen-host interface, Nature Reviews Microbiology 10
  • Gökhan Hacisalihoglu and Leon V. Kochian, 2003, How do some plants tolerate low levels of soil zinc? Mechanisms of zinc efficiency in crop plants, New Phytologist 159
  • Dominique Expert, Thierry Franza and Alia Dellagi, 2012 Iron in Plant-Pathogen Interactions, Chapter 2
  • Christa Fisher Walker, et al., 2005, Interactive effects of iron and zinc on biochemical and functional outcomes in supplementation trials, American Journal of Nutrition, 82:5

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