Generation and characterization of a soybean line with a Vernonia galamensis diacylglycerol acyltransferase-1 gene and a myo-inositol 1-phosphate synthase knockout mutation

Authors: AL-AMERY, MAYTHEM - University Of Baghdad; FOWLER, ASHLEY - University Of Kentucky; UNRINE, JASON - University Of Kentucky; Armstrong, Paul; Maghirang, Elizabeth; SU, KAI - University Of Kentucky; DE MELO, JULIA - Universidade Estadual Paulista (UNESP); YUAN, FENG-JIE - Zhejiang University; SHU, QING-YAO - Zhejiang University; HILDEBRAND, DAVID - University Of Kentucky

Submitted to: Lipids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2020
Publication Date: 6/15/2020
Citation: Al-Amery, M., Fowler, A., Unrine, J.M., Armstrong, P.R., Maghirang, E.B., Su, K., De Melo, J., Yuan, F., Shu, Q., Hildebrand, D. 2020. Generation and characterization of a soybean line with a Vernonia galamensis diacylglycerol acyltransferase-1 gene and a myo-inositol 1-phosphate synthase knockout mutation. Lipids. 12253. https://doi.org/10.1002/lipd.12253.
DOI: https://doi.org/10.1002/lipd.12253

Interpretive Summary: Soybean is an important source of protein, oil, and high protein meal for animal feed. The majority of phosphorus in the seeds is in the form of phytic acid or phytate and some inorganic phosphorus. Phytic acid is unavailable to animals such as poultry and fish and phytic acid can make some metals nutritionally unavailable. To overcome this problem, the addition of inorganic phosphorus or microbial phytase to animal feed is commonly practiced to increase available phosphorus. However, excretion of phytic acid can lead to accumulation of phosphorus in soil and water, and contribute to eutrophication of fresh water and near-coastal seawaters. Mutant seeds with low phytate and high phosphate have been identified which can potentially reduce these problems, and can increase the nutritional value of soybean meal by increasing its digestibility. This mutant soybean was crossed with a high oil line to try to produce new lines with increased inorganic phosphorus, lower phytic acid and maintain high oil and protein. The high oil content was maintained in greenhouse plants but not from field plants while protein levels were maintained in field grown plants but lower in greenhouse plants. Phosphate levels were significantly increased and phytate significantly reduced in comparison to most other evaluated lines. Thus, combining the high oil line with a low phytate high phosphate mutant can result in further improved soybean seed compositional attributes that are highly desirable for animal nutrition, but traits need to be added to increase oil levels.

Technical Abstract: Soybean (Glycine max) meal is an important protein source. Soybean meal with lower phytate and oligosaccharides improves meal quality. A single recessive mutation in soybean myo-inositol 1-phosphate synthase (Gm-lpa-TW75-1) confers a seed phenotype with low phytate and increased inorganic phosphate. The mutant was crossed with high oil lines expressing a diacylglycerol acyltransferase1 (DGAT) gene from Vernonia galamensis (VgD). Gm-lpa-TW75-1 X VgD, designated GV, has 21%, and 22 % oil and 41% and 43% protein from field and greenhouse seed production, respectively. No significant differences were found in mineral concentrations except for Fe which was 229 µg/g dry mass for GV followed by 174.3 for VgD and 162 for Gm-lpa-TW75-1. Phosphate (Pi) is higher in Gm-lpa-TW75-1 as expected at 5 mg/g, followed by GV at 1.6 mg/g whereas Jack, VgD and Taiwan75 have about 0.3 mg/g. The Gm-lpa-TW75-1 line has the lowest phytate concentration at 1.4 mg/g followed by GV with 1.8 mg/g compared to Taiwan75, VgD and Jack with 2.5 mg/g. This work describes a high oil and protein soybean line, GV, with increased Pi and lower phytate which will increase, the nutritional value for human and animal feed.