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Impact of environment on the biomass composition of soybean (Glycine max) seeds Tamara McClure, Jean Christophe Cocuron, Veronika Osmark, Leah McHale, and Ana Paula Alonso J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.7b01457 • Publication Date (Web): 19 Jul 2017 Downloaded from http://pubs.acs.org on July 21, 2017
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Journal of Agricultural and Food Chemistry
TITLE: Impact of environment on the biomass composition of soybean (Glycine max) seeds
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AUTHORS: Tamara McClure
, Jean-Christophe Cocuron
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McHale b,d,e, Ana Paula Alonso a,b,e,*
a,b
, Veronika Osmark c, Leah K.
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AFFILIATIONS:
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a
The Ohio State University, Department of Molecular Genetics, Columbus, OH 43210, USA
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b
The Ohio State University, Center for Applied Plant Sciences, Columbus, OH 43210, USA
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c
Høgskolen i Sør Trøndelag, Trondheim, 7004, Norway
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d
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43210, USA
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e
The Ohio State University, Department of Horticulture and Crop Science, Columbus, OH
The Ohio State University, Center for Soybean Research, Columbus, OH 43210, USA
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*
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Genetics, 054 Rightmire Hall, 1060 Carmack Road, Columbus, OH, USA.
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Email:
[email protected]; Ph: +001-614-688-7404; Fax: +001-614-247-8937.
Corresponding author: Dr. Ana P. Alonso, The Ohio State University, Department of Molecular
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ABSTRACT:
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Factors including genetics, fertilization, and climatic conditions, can alter the biomass
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composition of soybean seeds, consequently impacting their market value and usage. This study
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specifically determined the content of protein and oil, as well as the composition of
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proteinogenic amino acids and fatty acids in seeds from ten diverse soybean cultivars grown in
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four different sites. The results highlighted that different environments produce a different
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composition for the ten cultivars under investigation. Specifically, the levels of oleic and linoleic
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acids, important contributors to oil stability, were negatively correlated. Although the protein and
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oil contents were higher in some locations, their “quality” was lower in terms of composition of
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essential amino acids and oleic acid, respectively. Finally, proteinogenic histidine and glutamate
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were the main contributors to the separation between Central and Northern growing sites. Taken
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together, these results can guide future breeding and engineering efforts aiming to develop
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specialized soybean lines.
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KEYWORDS: Soybean; crop improvement; biomass composition; oil; protein; essential fatty
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acids; essential amino acids
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Journal of Agricultural and Food Chemistry
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MAIN TEXT:
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1. Introduction
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The soybean plant (Glycine max (L.) Merrill) is a species of legume that produces pods
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containing beans. Current soybean cultivars are phenotypically distinct from their wild relative
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Glycine soja due to the selection pressures occurring over thousands of years of agricultural
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production1 and ongoing plant breeding efforts2. The fresh beans from green pods can be eaten as
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a vegetable, and dry mature seeds are used not only in animal feeds and human foods that
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contain soybean oil or meal, but also in industry (solvents, lubricants, inks, plastics, waxes, etc)3.
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The market value of soybean stems largely from the significant oil and protein content of its
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seeds which accounts for approximately 40% and 20% of total dry weight, respectively, giving
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the seeds appreciable versatility4-5. Because of these attributes, soybean accounts for a significant
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amount of the world’s vegetable oil, animal fodder and food for human consumption.
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Soybean is an integral part of the diet of many Asian cultures with applications in items
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such as soymilk, soy sauce, soy paste, edamame, tempeh, miso, tofu and natto3. Among western
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cultures soybean is used mostly for its meal and oil. In 2014, 47.7% of soybeans produced in the
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United States were crushed domestically for oil and meal, 46.9% was exported, and the
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remaining was used for seed and other purposes. Soybean exports have increased by about 85%
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from 2000 to 2014, from 996 to 1843 million bushels, for a total price of $18.6 billion in 20146.
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The United States is a top soybean producer along with Brazil and followed by Argentina, China
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and India. According to the United States Department of Agriculture, soybeans comprise about
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90% of US oilseed production and make up the world’s largest protein source in animal feed and
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second largest source of vegetable oil, emphasizing not only the United States' role as a major
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producer, but also the global demand for soybean. US soybean production is the highest in
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Midwestern states including Illinois, Iowa, Minnesota, Indiana, Nebraska and Ohio7. Research
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regarding soybean is relevant in the context of these major regions of production.
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Both breeding programs and genetic modification efforts are used for the purpose of
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creating specialized soybean lines. Successful efforts include the creation of soybean lines with
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increased target nutrients, and others with resistances to herbicides, pesticides, and pathogens8-10.
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Breeding has been a widely employed strategy for improving soybean for over two thousand
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years2, and genetically modified soybeans have been commercially grown in the U.S. since
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199611. Current soybean breeding programs and genetic modification efforts aim to improve
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nutritional value, amongst other traits. Specifically, soybean seed biomass components such as
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protein and oil content and composition have been targeted in research due to their importance to
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the soybean market12.
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Traditional soybean oil is mainly comprised of palmitic acid (C16:0, approximately 10%
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of crude oil), stearic acid (C18:0, approx. 4%), oleic acid (C18:1, approx. 22%), and essential
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linoleic (C18:2, omega-6, approx. 54%) and linolenic (C18:3, omega-3, 10%) acids, which are
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necessary for health and must be obtained by consumption13. Though essential and desirable for
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human health, linolenic and linoleic acids are responsible for oxidative instability of soybean oil,
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which has been historically addressed through partial hydrogenation4-5. Once hydrogenated and
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refined, soybean oil is a stable source of vegetable oil, however this is at the cost of health, as the
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trans-fats that result from the hydrogenation process have been shown to increase the risk of
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coronary heart disease5, 14. Naturally high oleic acid content in soybean (target value >70% of
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total oil) is valuable due to this monounsaturated omega-9 fatty acid’s stability at high
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temperatures, which reduces the formation of trans-fats during vegetable oil production and use5.
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For the same reason, low linolenic soybean (target value
