Research Project: Advancing the Nutritional Quality of Staple Food Crops for Improved Intestinal Function and Health

Location: Plant, Soil and Nutrition Research

2021 Annual Report

Objectives
Objective 1: In collaboration with plant breeders, utilize in vitro, in vivo, and analytical techniques to evaluate Fe bioavailability in staple food crops (beans, wheat, maize) for the purpose of developing crops that serve as an improved source of Fe. [NP107, C1, PS1A] Sub-objective 1.A. Collaborate with breeders to develop bean varieties with enhanced Fe bioavailability that can deliver more absorbable Fe and be a highly sustainable source of dietary Fe. Sub-objective 1.B. Characterize the potential genotype x environment (GxE) interactions that influence Fe content and Fe bioavailability in beans; and determine if either content, bioavailability or both can be sustainable approaches to improve Fe nutrition from beans. Sub-objective 1.C. Collaborate with breeders to characterize Fe bioavailability and Fe concentration from the different components of the maize and wheat grain, and search for QTL for enhanced Fe bioavailability and content of these components. Objective 2. Characterize the individual and interactive effects of dietary minerals (Fe and Zn), phytochemicals and prebiotics common to staple foods (chickpea, bean, wheat, lentil) on the intestinal microbiome and intestinal brush border membrane functionality. [NP107, C3, PS3B] Sub-objective 2.A. Evaluate the effect of natural prebiotics and phytochemicals extracted from staple food crops on mineral (Fe, Zn) dietary bioavailability and absorption in vivo (Gallus gallus).

Approach
As iron and zinc deficiencies are affecting approximately 30% of the world’s populations, including about 15% of the US population, the focus of this research plan is to improve iron bioavailability in staple food crops and to further increase their consumer appeal. Further, we aim to characterize the individual and interactive effects of dietary minerals (Fe and Zn), phytochemicals and prebiotics common to staple foods (chickpea, bean, wheat, lentil) on the intestinal microbiome and intestinal brush border membrane functionality. This will be done in order to evaluate the effect of natural prebiotics and phytochemicals extracted from staple food crops on mineral (Fe, Zn) dietary bioavailability and absorption in vivo (Gallus gallus). In addition, as the newly accepted body “organ”, the intestinal microbiome plays a vital role in the functionality, absorption and digestion capabilities of the intestine; hence, we aim to characterize the microbiome response to dietary plant origin bioactive compounds that may contribute to intestinal functionality and overall health. To accomplish the above, we will employ our established screening tools of an iron bioavailability bioassay and a poultry model that reflects human nutrition. In conjunction, we will make use of techniques such as mass spectroscopy, marker assisted molecular breeding, our Zinc Status biomarker, gene expression, microscopy, and state of the art microbial profiling techniques. With this unique combination of tools, we expect to develop staple food crops with enhanced iron nutrition and elucidate factors that can improve zinc nutrition from staple food crops, and thereby contribute to alleviation of two of the leading micronutrient deficiencies in the world. We will also expand knowledge of how the intestinal microbiome is affected by dietary iron, zinc, phytochemicals and prebiotics. Overall, this knowledge will further contribute to food innovations with enhanced nutrition and improve human health both domestically and abroad.

Progress Report
Research on beans was a major focus of this fiscal year. Significant progress continues on identifying and developing bean varieties that provide enhanced Fe nutrition. We now have yellow bean varieties, both domestically and abroad with collaborators in Uganda, that are established as fast cooking and high bioavailable Fe. In combination, these are two traits that should significantly promote bean consumption. Research also shows that genotype by environment (GxE) interactions significantly influence Fe concentration, yet effects on Fe bioavailability are minimal. These results further support a shift in approach to improving Fe nutrition from beans, focusing more on factors that enhance Fe bioavailability. A review article was published this year by the lead scientist on this subject. Summaries of more specific research on beans are listed below. Yellow By Yellow Recombinant Inbred Line (YYRIL) Mapping Population. Completed measuring the mineral content and iron bioavailability of a Manteca yellow bean (Ervilha) x Njano yellow bean (PI527538) mapping population (400+ RILS over two field seasons) to identify promising molecular markers (QTL) for the high iron bioavailability trait in fast cooking Manteca yellow beans. A QTL located near the j allele on chromosome 10 has been identified as a strong candidate marker for high iron bioavailability in beans after cooking. The j allele is characterized as an important region of the genome that inhibits the production of condensed tannins (procyanidins and cinnamtannins) in the seed coats of yellow beans. A manuscript describing the results of this study is now in preparation. Genotype by Environment (G x E) Studies in Uganda. Working with breeders and international partners (USAID) to design Phase 2 of the Uganda GxE on-farm trials. Phase 2 will evaluate new promising breeding lines with high yields, fast cooking times, and high iron bioavailability in different growing regions throughout Uganda. Domestic Genotype by Environment (G x E) Studies. The first of two years is completed for the evaluation of mineral content and iron bioavailability of a large group of fast and slow cooking yellow beans produced in Michigan (normal soil pH 7) and Nebraska (high soil pH > 8). This study aims to determine the likelihood of producing high iron bioavailable yellow beans domestically for the use as a specialty market class devoted to addressing the iron needs of vulnerable populations in the United States and globally. Dietary Fiber Analysis of Fast Cooking Yellow Beans. Recently evaluated the relationship between total dietary fiber, cooking time, and iron bioavailability in a large group of yellow beans selected from the USDA’s Yellow Bean Collection (est. 2018). There was a significant relationship between the total dietary fiber (AOAC 2011.25) concentrations and cooking times of yellow beans, which were collected from each of the major bean-consuming regions of the world. In addition, there was a significant relationship between the insoluble dietary fiber concentrations and iron bioavailability of fast cooking yellow beans, indicating that new breeding targets for total dietary fiber (AOAC 2011.25) can be implemented to further enhance the iron bioavailability of new yellow bean varieties. A manuscript describing the results of this study is now in preparation. Optical Sensing Technology to Predict Iron Bioavailability from Intact Dry Beans. Hyperspectral analysis of the USDA’s Yellow Bean Collection (300+ genotypes) over the course of three fields seasons has been conducted, and results of the study demonstrate how the use of machine learning can be used to predict important nutritional traits from intact yellow beans, such as mineral content and iron bioavailability. A manuscript is now in preparation. Slow-Darkening Pinto Beans Have Improved Iron Bioavailability. A significant relationship between condensed tannin concentrations (procyanidins) and iron bioavailability was recently demonstrated in pinto beans with slow-darkening seed coats. Seed coat darkening after a delayed harvest or prolonged storage reduces the commercial value of pinto beans and is caused by the oxidation of procyanidin compounds (condensed tannins). Slow-darkening (SD) pinto beans have a recessive gene (P.D.), which alters procyanidin production – postponing their darkening over time. This study compared the postharvest cooking times and iron bioavailability of slow-darkening pinto bean varieties to regular-darkening pinto varieties across five producing sites in North Dakota. The results show slow-darkening pinto beans cook 30% faster and provide 2-7 times more bioavailable iron than regular-darkening pinto beans. This study demonstrates that downregulating the synthesis procyanidins with the Psd gene could be a novel breeding strategy to improve the cooking quality and iron bioavailability of other dry bean commercial classes that are prone to seed coat darkening, such as carioca, cranberry (sugar), pink, red kidney and yellow.

Accomplishments
1. Identification and development of fast-cooking yellow bean varieties with enhanced Fe bioavailability. In East Africa, fast-cooking beans are highly desirable due to scarcity of cooking fuel; iron deficiency anemia is high in this region, and beans are a widely consumed staple food crop that can alleviate Fe deficiency. Increasing bean consumption in the U.S. is a priority, and recent U.S. surveys indicate decreased Fe intake is associated with increased Fe deficiency anemia. Therefore, traits such as fast cooking and improved Fe nutrition can promote this agency goal and provide improved sources of Fe. ARS scientists at Ithaca, New York, in collaboration with ARS researchers at East Lansing, Michigan, developed varieties of fast-cooking yellow beans via traditional breeding coupled with highly validated cell culture and animal studies to deliver enhanced absorbable iron levels. The development of bean varieties in the U.S. enables bean growers to expand the local market for beans with value-added bean-based food products.

Review Publications
Glahn, R.P., Wiesinger, J.A., Lung'Aho, M. 2020. Biofortified beans of East Africa are not significantly higher in iron content relative to non-biofortified marketplace varieties. Journal of Nutrition. https://doi.org/10.1093/jn/nxaa193.
Gannon, B., Glahn, R.P., Mehta, S. 2019. Iron bioavailability from multiple biofortified foods using an in vitro digestion, Caco-2 assay for optimizing a cyclical menu for a randomized efficacy trial (P10-029-19). Current Developments in Nutrition. 3(1). https://doi.org/10.1093/cdn/nzz034.P10-029-19.
Wiesinger, J.A., Cichy, K.A., Hooper, S., Hart, J.J., Glahn, R.P. 2020. Processing white or yellow dry beans (phaseolus vulgaris L.) into a heat treated flour enhances the iron bioavailability of bean-based pastas. Journal of Functional Foods. 71:104018.
Katuuramu, D.N., Wiesinger, J.A., Luyima, G.B., Nkalubo, S.T., Glahn, R.P., Cichy, K.A. 2021. Investigation of genotype by environment interactions for seed zinc and iron concentration and iron bioavailability in common bean. Frontiers in Plant Science. 12:670965. https://doi.org/10.3389/fpls.2021.670965.
Podder, R., Glahn, R.P., Vandenberg, A. 2021. Dual-fortified lentil products - a sustainable new approach to provide additional bioavailable iron and zinc in humans. Current Developments in Nutrition. 01/30/2021.
Podder, R., Glahn, R.P., Vandenberg, A. 2021. Iron and zinc fortified lentil (Lens culinaris Medik.) demonstrate enhanced and stable iron bioavailability after storage. Frontiers in Nutrition. 7:614812. https://doi.org/10.3389/fnut.2020.614812.
Wright, T.I., Gardner, K., Glahn, R.P., Milner, M.J. 2021. Genetic control of iron bioavailability is independent from iron concentration in a diverse winter wheat mapping population. Biomed Central (BMC) Plant Biology. 21:212-225. https://doi.org/10.1186/s12870-021-02996-6.
Wiesinger, J.A., Osorno, J.M., Mcclean, P.E., Hart, J.J., Glahn, R.P. 2021. Faster cooking times and improved iron bioavailability are associated with the down regulation of procyanidin synthesis in slow-darkening pinto beans (Phaseolus vulgaris L.). Journal of Functional Foods. 82:104444. https://doi.org/10.1016/j.jff.2021.104444.
Broad, R., Bonneau, J., Beasley, J., Roden, S., Sadowski, P., Berger, B., Tako, E., Glahn, R.P., Hellens, R., Johnson, A. 2020. Effect of rice GDP-L-Galactose phosphorylase constitutive overexpression on ascorbate concentrations, stress tolerance, and iron bioavailability in rice. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2020.595439.
Sabatier, M., Rytz, A., Dubascoux, S., Nicolas, M., Dave, A., Singh, H., Bodis, M., Glahn, R.P. 2020. Impact of Ascorbic acid on the in vitro Iron bioavailability of a casein-based iron fortificant in comparison to ferrous sulfate and ferric pyrophosphate. Nutrients. 12(9):2776. https://doi.org/10.3390/nu12092776.