Phosphorus Partitioning of Soybean Lines Containing Different Mutant Alleles of Two Soybean Seed‐Specific Adenosine Triphosphate‐Binding Cassette Phytic Acid Transporter Paralogs

Abstract

Seed phytate is a repository of P and minerals in soybean [Glycine max (L.) Merr.] seeds that limits P and mineral bioavailability for monogastric animals (e.g., humans, swine [Sus scrofa], and poultry [especially chicken, Gallus domesticus]) due to insuffi cient digestive tract phytase activity. We previously identifi ed epistatic recessive mutations affecting two paralogous adenosine triphosphate-binding cassette phytic acid transporter genes (one a nonsense mutation in Lpa1 and the other a missense mutation in Lpa2) as the molecular genetic basis in the ethyl methanesulfonate (EMS)-induced mutant low phytate soybean line M153. An additional mutant low phytate line, M766, contained one single nucleotide polymorphism within the ninth intron of the Lpa1 locus as well as a nonsense mutation in Lpa2. The objectives of this research were to clarify the genetics underlying the low phytate phenotype in line M766 and to determine P partitioning in new combinations of mutant alleles from M766 and M153. Inheritance of nonsense alleles affecting both low phytic acid (Lpa) genes (one from M153 and one from M766) led to the production of viable seeds that contained transgressive reductions in total seed phytate and signifi cantly higher levels of inorganic phosphate than has been reported for nontransgenic soybean material and will allow effi cient molecular selection of soybeans with even greater reductions of phytate for improved quality soybean meal.

Phytic Acid and Inorganic Phosphate Composition in Soybean Lines with Independent IPK1 Mutations

“…The severe reduction in PA‐P sets the double mutant 14m/06m class apart from the 14m/06W class. The striking accumulation of P in lower inositols rather than Pi‐P distinguishes the double mutant 14m/06m class from the soybean lpa1 ‐ lpa2 transporter mutant combinations (Gillman et al, 2013; Yuan et al, 2007).…”

“…Multiple independent sources of lpa soybean lines were discovered and characterized (Sebastian et al, 2000; Wilcox et al, 2000, Yuan et al, 2007; Maroof and Buss, 2011). Further investigation into the genetics of these lines identified mutations in genes encoding enzymes in the PA biosynthesis pathway and PA transporter genes (Gillman et al, 2013, 2009; Hitz et al, 2002; Yuan et al, 2012). Unfortunately, many soybean lpa mutants have significantly reduced germination and emergence (Anderson and Fehr, 2008; Maupin and Rainey, 2011; Maupin et al, 2011; Meis et al, 2003; Yuan et al, 2007).…”

Impact of mips1, lpa1, and lpa2 Alleles for Low Phytic Acid Content on Agronomic, Seed Quality, and Seed Composition Traits of Soybean

“…Thus, although PA may be produced in lines with the lpa1 allele, that PA will not be efficiently partitioned into the seed. The lpa2 allele contains a nonsense mutation to a gene also involved in the ABC transporter in the latter part of the PA production pathway (Gillman et al, 2013). Although this mutation decreases the amount of PA produced, other inositol kinases may compensate for its lack of production, leading to this mutation having a much more minor effect on the overall PA content of the seed than lpa1 (Pilu et al, 2009).…”

Soybean (Glycine max) Mutant and Germplasm Resources: Current Status and Future Prospects

“…() demonstrated the proof of concept for conducting chemical mutagenesis and identification of mutations in soybean using a strategy called Targeting Induced Local Lesions IN Genomes (TILLING; McCallum et al., ). These mutant populations have resulted in the identification of genes involved in disease resistance ( Rhg4 ; Liu et al., ), seed composition traits (e.g., Dierking and Bilyeu, ; Gillman et al., ; Carrero‐Colón et al., ; Hoshino et al., ), maturity and flowering time loci (Watanabe et al., , ; Xia et al., ) as well as providing a wealth of knowledge about various biochemical and physiological processes (Table ). While there is substantial community interest in further developing chemically mutagenized populations for soybean research and breeding (e.g., Tsuda et al., ), to our knowledge no such populations are currently considered “public” resources.…”