Q&A about biofortified sorghum

In the post What do you want to know about biofortified sorghum? we invited you to ask questions of Marc Albertsen, DuPont Pioneer’s team lead for the African Biofortified Sorghum (ABS) project (see his bio below). Dr. Albertsen’s has provided detailed responses.

1. How did DuPont Pioneer get involved in this project? Were they one of the founders or did the project already exist when DuPont Pioneer got involved?

The CEO of Africa Harvest, Dr. Florence Wambugu, was one of the DuPont International Biotechnology Advisory Committee members during the early 2000’s. In one of the Advisory Committee meetings, we presented some of Pioneer’s new biotechnology advancements that happened to include sorghum transformation and lysine-enhanced sorghum seed. Dr. Wambugu thought this was a good opportunity for Africa, and she discussed the possibilities of using this technology for sorghum nutrition improvement for Africa. Dr. Paul Anderson, one of the research directors at that time responsible for improving the nutritional profile of certain of Pioneer’s crops, worked with Dr. Wambugu to seek outside grant support and discovered that the Gates Foundation was accepting grant proposals for biofortification of key crops in sub-Saharan Africa. He organized a group of people to develop the grant proposal, along with African Harvest. The proposal eventually was accepted and one of the Gates Foundation’s “Grand Challenges” for biofortification was initiated.
Check out the African Biofortified Sorghum (ABS) fact sheet to learn more about the initiative.

2. How did you decide which nutrients to enhance? Did you have to consider how nutrients in the food affect each other?

The focus was on sorghum, as studies had estimated that there are 300 million people that rely on sorghum as their staple diet in sub-Saharan Africa. Sorghum provides reasonable calories, but it is known to be deficient in pro-vitamin A (beta-carotene), iron, and zinc. It is also known that a significant proportion of the protein that is present in sorghum becomes indigestible after cooking. We were fairly confident that we could leverage our work in maize on protein modification into improving the digestibility of sorghum protein. We were also confident that we could leverage beta-carotene enhancement advancements from the Golden Rice© effort.
We knew from the literature that iron and zinc bioavailability were impacted by the same mechanism, so we were confident that improving the bioavailability of iron would impact the bioavailability of zinc, and vice versa, so we could use this to our advantage. Additionally, there is little connection between improving levels of beta-carotene and improving bioavailability of iron and zinc, so impacting the levels of beta-carotene was not expected to impact iron and/or zinc bioavailability.

3. Is the sorghum engineered for anything besides nutritional changes?

No. Nutritional changes are the only changes we have introduced into biofortified sorghum.

4. Have the increases in some amino acids resulted in decreases in other amino acids? Do the total changes in amino acids result in a better amino acid balance for humans?

We were successful in altering the amino acid profile of sorghum that enhanced levels of lysine, threonine, and tryptophan for human benefit, but unfortunately, these modifications resulted in a sorghum kernel that was relatively soft. We decided not to proceed any further on this front, but instead, concentrated on producing protein in the sorghum grain that was more digestible after cooking without impacting the original kernel hardness.

5. For humans to have optimal metabolism of Vitamin A from beta carotene, some amount of fat is needed. Is there enough fat in sorghum to alleviate this concern? Are processing or other foods needed to facilitate nutritionally meaningful absorption of the nutrients in the sorghum?

This is an important consideration that is often overlooked by people when discussing the benefits of beta-carotene. We have had several discussions internally and with food science experts specifically to address this issue. Introducing beta-carotene with oil is the most effective way of delivering beta-carotene to humans. However, oil is not the only factor that affects the bioavailability of beta-carotene.  Tissue composition, such as the fiber content, affects the bioavailability of beta-carotene as well. That’s why the bioavailability of beta-carotene for different types of food needs to be determined and compared in oil. Beta-carotene produced by Golden Rice© is a better source of pro-vitamin A for humans than that produced by spinach and carrots. This is because the conversion rate of beta-carotene to vitamin A in golden rice (3.8:1) is much more efficient than that in colored vegetables (10:1 to 27:1) as determined.  Like Golden Rice©, sorghum is a starchy grain and itself will not provide enough oil for efficient beta-carotene metabolism.
The important question, however, is whether the beta-carotene from biofortified sorghum will be a better source of pro-vitamin A than spinach or carrots, and how much RDA (Recommended Daily Allowance) that biofortified sorghum can provide. Consuming beta-carotene in sorghum with fat-enriched meals would increase the absorption of beta-carotene from sorghum, but this usually just isn’t an option.

6. Has there been any testing to determine the efficacy of nutrient absorption? How quickly does the beta carotene degrade in the absence of processing and/or refrigeration after harvest?

Initial studies have been completed and analysis is underway to determine the conversion rate of beta-carotene to retinol, the component that is utilized by the human body to produce vitamin A.
Unfortunately, beta-carotene has a half life of 3 weeks in sorghum, that is, after 3 weeks, one half of the beta-carotene present is degraded. Our research has enabled us to extend that to about 10 weeks.

7. Has any testing (such as “-omics”) been used to detect reductions of beneficial compounds, increases in detrimental compounds, or additions of unfamiliar compounds?

Not yet. These kinds of tests will be done during the deregulation process. We do not anticipate any negative issues.

8. What is the plan for patents and licensing? Will there be any penalties for farmers growing seed without permission?

There are no plans for patents or licensing as it applies to subsistence farmers. They will be able to re-grow biofortified seeds without penalty.

9. What is the timeline for release? How much time is needed for breeding and testing vs how much time is anticipated for regulation?

We plan to have to the final event identified by the end of 2014 or early 2015. Depending upon the number of seed advance generations per year, it will likely take two to three years to introgress the transgene cassette into local varieties. Much of the deregulation activities can be conducted simultaneously with the introgression activities. We are anticipating a 4-6 year deregulation process in Africa.
The Biofortified sorghum initiative is on track and well positioned for future progress. We recently provided an update on project milestones.

10. Many African nations push back against the production of genetically modified crops due to a lack of markets in European countries. Do you see this stigma affecting the adoption of biofortified sorghum?

Realistically, this could be an issue. I would point out, however, that sorghum is currently not exported from Africa. This is especially true for sub-Saharan Africa where sorghum is an internally consumed crop. From a purely scientific perspective, sorghum varieties, whether transgenic or not, cannot cross with any other grain crop and therefore should not present an issue when it comes to exporting any other grain or vegetable crop.

11. Has material from public gene banks been useful in this work? Is there any gene bank material you’d like to use in the future? Will any material from this project be added to gene banks?

Not directly, as the initial focus will be on utilizing native sorghum varieties into which the biofortification genes will be placed. As the program progresses, it may well be that gene bank material might be utilized to further improve the varieties with biofortification. If the gene banks would find this material useful to have in their collections, then there would be no reason not to include it for future use and improvement.
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Dr. Marc Albertsen is the DuPont Pioneer leader of two philanthropic, multi-partner, public-private-partnerships, each with the goal of improving the lives of subsistence farmers in Africa. One of these is the Africa Biofortified Sorghum (ABS) project, which is developing nutritionally enhanced sorghum to enhance the lives of people dependent upon sorghum for their staple diet. The other is the Improved Maize for African Soils (IMAS) project, which is improving the nitrogen use efficiency of maize for subsistence farmers through a combination of conventional, molecular, and transgenic breeding.
Dr. Albertsen has over 32 years of research and leadership experience at DuPont Pioneer in reproductive biology and agronomic traits with a background that combines genetics, cytogenetics, crop breeding, cytology, molecular biology, and plant physiology. He has authored or co-authored over 25 refereed journal articles, over 60 additional professional article and abstracts, and over 45 patents.
Dr. Albertsen holds a doctorate in Plant Breeding and Genetics from the University of Minnesota, a master’s degree in Plant Breeding and Cytogenetics and a bachelor’s degree in Botany from Iowa State University (go Cyclones!). He pursued postdoctoral research at Iowa State before joining Pioneer. His career has been marked by many honors and awards, including being named a Fellow of the Crop Science Society of America in 2012.
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