On the Inverse Correlation of Protein and Oil: Examining the Effects of Altered Central Carbon Metabolism on Seed Composition Using Soybean Fast Neutron Mutants.

Shrikaar Kambhampati,Doug K Allen,Jose A Aznar-Moreno,Allen H Hubbard,Cooper Hostetler,Tara Caso,Sally R Bailey,Timothy P Durrett

doi:10.3390/metabo10010018

Abstract

Protein and oil levels measured at maturity are inversely correlated across soybean lines; however, carbon is in limited supply during maturation resulting in tradeoffs for the production of other reserves including oligosaccharides. During the late stages of seed development, the allocation of carbon for storage reserves changes. Lipid and protein levels decline while concentrations of indigestible raffinose family oligosaccharides (RFOs) increase, leading to a decreased crop value. Since the maternal source of carbon is diminished during seed maturation stages of development, carbon supplied to RFO synthesis likely comes from an internal, turned-over source and may contribute to the reduction in protein and lipid content in mature seeds. In this study, fast neutron (FN) mutagenized soybean populations with deletions in central carbon metabolic genes were examined for trends in oil, protein, sugar, and RFO accumulation leading to an altered final composition. Two lines with concurrent increases in oil and protein, by combined 10%, were identified. A delayed switch in carbon allocation towards RFO biosynthesis resulted in extended lipid accumulation and without compromising protein. Strategies for future soybean improvement using FN resources are described.

Highlights

Soybean (Glycine max) is a versatile and important crop with many uses
Soybean (Glycine max) seeds selected for gene mutations in central carbon metabolism were obtained from two fast neutron (FN) mutagenized populations developed at the University of Missouri (MO) and the University of Minnesota (MN) with the USDA (Table 1)
The first collection consisted of 8 lines from a mutant population developed at the University of Missouri, Columbia from the “Williams 82” background and the second consisted of 17 lines from a mutant population developed at the University of Minnesota and USDA using the background

Summary

Introduction

In 2017, 80 million acres of soybeans were planted in the United States (United States Department of Agriculture (USDA), National Agricultural Statistics Service (NASS)). The value of soybean is mostly due to high protein content with balanced amino acid composition that is used to produce feed for livestock and high seed oil content that is a primary source of vegetable oil and the feed stock for biofuel production. Soybean protein represents approximately 35–40% of the total biomass in soybeans and is the component of greatest value in soybean meal. Metabolites 2020, 10, 18; doi:10.3390/metabo10010018 www.mdpi.com/journal/metabolites represent a metabolizable energy source in animal feed, but raffinose and stachyose that are members of the raffinose family oligosaccharides (RFOs) are indigestible and undesirable for livestock production [5,6]. RFOs have hypothesized roles in seed desiccation tolerance [7,8,9], stability of liposomes during dehydration, and seed germination [10,11,12], efforts in breeding and Metabolites

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Conclusion