Generation and characterization of two novel low phytate mutations in soybean (Glycine max L. Merr.)

Abstract

Phytic acid (PA, myo-inositol 1, 2, 3, 4, 5, 6 hexakisphosphate) is important to the nutritional quality of soybean meal. Organic phosphorus (P) in PA is indigestible in humans and non-ruminant animals, which affects nutrition and causes P pollution of ground water from animal wastes. Two novel soybean [(Glycine max L. (Merr.)] low phytic acid (lpa) mutations were isolated and characterized. Gm-lpa-TW-1 had a phytic acid P (PA-P) reduction of 66.6% and a sixfold increase in inorganic P (Pi), and Gm-lpa-ZC-2 had a PA-P reduction of 46.3% and a 1.4-fold increase in Pi, compared with their respective non-mutant progenitor lines. The reduction of PA-P and increase of Pi in Gm-lpa-TW-1 were molar equivalent; the decrease of PA-P in Gm-lpa-ZC-2, however, was accompanied by the increase of both Pi and lower inositol phosphates. In both mutant lines, the total P content remained similar to their wild type parents. The two lpa mutations were both inherited in a single recessive gene model but were non-allelic. Sequence data and progeny analysis indicate that Gm-lpa-TW-1 lpa mutation resulted from a 2 bp deletion in the soybean D: -myo-inositol 3-phosphate synthase (MIPS1 EC 5.5.1.4) gene 1 (MIPS1). The lpa mutation in Gm-lpa-ZC-2 was mapped on LG B2, closely linked with microsatellite loci Satt416 and Satt168, at genetic distances of approximately 4.63 and approximately 9.25 cM, respectively. Thus this mutation probably represents a novel soybean lpa locus. The seed emergence rate of Gm-lpa-ZC-2 was similar to its progenitor line and was not affected by seed source and its lpa mutation. However, Gm-lpa-TW-1 had a significantly reduced field emergence when seeds were produced in a subtropic environment. Field tests of the mutants and their progenies further demonstrated that the lpa mutation in Gm-lpa-ZC-2 does not negatively affect plant yield traits. These results will advance understanding of the genetic, biochemical and molecular control of PA synthesis in soybean. The novel lpa mutation in Gm-lpa-ZC-2, together with linked simple sequence repeat (SSR) markers, will be of value for breeding productive lpa soybeans, with meal high in digestible Pi eventually to improve animal nutrition and lessen environmental pollution.

TheArabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required forMyo-inositol Synthesis and Suppression of Cell Death

“…2000; Dorsch et al, 2003;Liu et al, 2007;Yuan et al, 2007). Our work on the MIPS genes in the model plant Arabidopsis points to specialized roles for individual MIPS genes, with the MIPS1 gene providing the greatest impact, overall, on myo-inositol, growth, development, and physiology.…”

Nutritionally Enhanced Staple Food Crops

“…The total seed phosphorus in these mutants was unaffected, while reduction in phytic acid resulted in corresponding increases in inorganic P in the seed. However, lp mutants, in general, had reduced germination and seedling development and yielded low compared to WT (Meis et al 2003;Pilu et al 2003;Oltmans et al 2005;Shi et al 2007), with some exception in barley (Bregitzer and Raboy 2006), soybean (Yuan et al 2007), and common bean (Campion et al 2009). Badone et al (2010) isolated a low phytic acid mutant in maize, lp1-241, with a reduction of up to 90% of phytic acid and strong pleiotropic effect on the whole plant including higher level of anthocyanins as compared to wild type either in the embryo ($3.8-fold) or in the aleurone layer ($0.3-fold).…”

Genetic variation for phytic acid content in mungbean (Vigna radiata L. Wilczek)

“…Recently there has been increasing interest in the development of crops with low phytic acid (lpa) content to enhance the bioavailability of minerals and other nutrients. Earlier breeding efforts have identified several lpa mutants, resulting in reduction of seed phytic acid phosphorus (PAP) by 50 to >95% in crops such as barley, wheat, maize, soybean, and common bean [9][10][11][12][13]. But no lpa mutant was identified in mungbean.…”