Nutrient deficiency in one’s diet is a common problem around the world, where different populations may lack a sufficient source of varying nutrients needed to stay healthy. Iron and zinc are two such nutrients that are critical for one’s daily intake. At the same time, common cultivars of wheat supply around 20% of daily calorie consumption alone for billions of people. So being able to combine and fortify wheat with extra micronutrients would kill two birds with one stone.
How To Fortify
Thus, regular fortification, where mineralized forms of the nutrients are added to bread dough, has long been a staple in many countries. But there are still plenty of populations, especially in rural areas of Africa and Asia, where they only grow their wheat locally and thus do not have access to the physical resources needed for fortifying their crops. Attempts have been made to get that sort of industrial process out to these regions, but it’s an expensive task.
Therefore biofortification, where the plants themselves produce the heightened levels of desired nutrients, continues to be a popular opportunity to help these communities meet their intake requirements and defeat malnutrition. Accomplishing this task, however, is far more than just expressing a gene that increases mineral production.
Other factors that aid in digestion and utilization of the micronutrients by the body, along with reducing the level of antinutritional compounds that can block or interfere with mineral uptake, have to be taken into account on the genetic level. The prime antagonist making up the latter in plants is phytic acid/phytate (IP) and it can not only sequester several mineral varieties, but also inorganic phosphate. These degenerative effects happen not only in humans, but livestock that eat plants as well, so the natural development of higher levels of IP must be continuously fought against.
A separate problem that must be faced when dealing with wheat is that the amount of genetic variation within the cultivars when it comes to iron, zinc, and related compounds is rather low and it is difficult for said genes to be inherited through normal breeding. Wild relatives and other related species have been the main go-to in order to find alternative mineral-accumulating traits that also don’t reduce yields or other characteristics.
The combined approach has been to look for mutant varieties that are low phytate (LPA) breeds and can serve as a base for introducing stronger micronutrient production genes. Researchers with the USDA’s Agricultural Research Service, in collaboration with the University of Nebraska – Lincoln and published by the American Society of Agronomy, decided to take up the task at hand and see if they could create just such a cultivar.
They started with a transgenic sample of winter wheat, a part of a recombinant inbred line (RIL), that is a genetic cross between an LPA parent and a mineral production gene locus parent. Multiple different lines from different parents with such traits were made into experimental groups under a single category, with a second group being LPA genes only, a third being overall mineral protein content (GPA) genes only, and then a final group being pure wild-type. Would these offspring be able to provide heightened grain protein and mineral levels, while not affecting yield and growth? The use of element dialyzability measurements, or the amount of bioavailable nutrients that are in a plant, would help determine if they succeeded.
For all the minerals and nutrients that were not a focus, there was no observed change in their quantity in the offspring crops. Overall grain protein amount, volume, and concentrations of certain compounds including magnesium, zinc, calcium, and others were increased. The scientists were also able to confirm that this was the first time ever that a dual LPA and GPA plant was tested and they showed that, unlike LPA cultivars alone, there was no reduction in grain yields. Even for target minerals like iron, the fact that their levels were maintained is an achievement as low phytic acid levels means more of that iron will be absorbed by the body.
Biofortification Science Continues
In total, this experiment showcased the ability to create a winter wheat cultivar with higher bioavailability of micronutrients like iron and zinc, along with improving other minerals as well. These traits have the potential to be bred into other forms of wheat and even beyond, hopefully conveying the same adjustments. If the traits are properly heritable at a high rate, then we might finally have a way to supply wheat that can help meet nutritional needs in places lacking food access to those necessary micronutrients.
Biofortification has, once again, shown a path toward better agriculture and the ability to prevent deaths from malnutrition.
Photo CCs: Acker-bei Sonnenuntergang-July2006 from Wikimedia Commons