Putative Second-Site Mutations in the Barley Low Phytic Acid 1-1 (lpa 1-1) Genetic Background Further Reduce Seed Total Phosphorus

Phytic acid is the major storage form of phosphorus in wheat grain. Non-ruminant animals cannot utilize phytic acid phosphorus, and phytic acid reduces the nutritional availability of important minerals. We have identified a wheat mutant (Lpa1-1) with reduced phytic acid P and increased inorganic P (Pi). Ideally, LPA wheats will have improved micronutrient availability without detrimental effects on baking quality. To test this hypothesis, the mutant phenotype was transferred via backcrossing into the hard red spring wheat cultivar ‘Grandin.’ Wild-type (WT) and low phytic acid (LPA) sib selections from two backcross families were grown in replicated, irrigated yield trials at Aberdeen, ID in 2003 and 2004. Total P, Pi, and phytic acid P (PAP) were measured in grain and in fractions obtained after milling on a Quadrumat Sr. experimental mill. Elemental concentrations (Ca, Cu, Fe, Mg, Mn, P, S, and Zn) were measured in flour and bran fractions by ICP mass spectrometry. Total P concentration in grain of WT and LPA sib lines was similar. However, the distribution of P between phytic acid and Pi was altered: Pi in LPA grain was up to 340% of WT grain, and PAP in LPA grain was reduced to as low as 65% of the concentration in WT grain. This difference in P composition of grain was reflected in flour: Pi in break and reduction flours of LPA wheat was 3- to 4-times the concentration in break and reduction flours from WT wheat. Total P concentration in LPA flours was 20% greater than in WT flours. Mineral concentrations in bran and shorts of LPA and WT wheats were similar. However, magnesium concentrations in LPA break and reduction flours were significantly greater than in WT flours. The LPA genotype had little effect on concentrations of other minerals. Increases in P and Mg concentration in LPA flours were manifested in greater flour ash concentration. Flour ash of WT flours averaged 3.86 g kg-1; flour ash of LPA flours averaged 4.38 g kg-1. Protein concentration of LPA and WT flours was similar. However, LPA flours had a longer time to mixograph peak and greater mixograph peak height than WT flours. Bread loaf volume of LPA and WT flours was similar. The results of this study indicate that the LPA trait can produce flours with greater Pi and Mg concentration and little effect on bread flour functionality

This review summarizes the environmentally friendly methods that are available to manage phosphorus (P) excretion. Phase feeding reduces P excretion up to 10–25% by adding precise amounts of P to broiler diets. Increasing of the Ca: P ratio in diets from 1: 1 to 2: 1 decreased the availability of P from phytic acid. Feeding diets supplemented with vitamin D can increase phytin P (PP) utilization from 31–50 to 68–87%. Total P (TP) excretion by poultry may be reduced by up to 50% through the use of supplemental phytase. Reductions in phytic acid P ranging from 50 to 65% with no decreases in TP of the seed were seen in ‘low-phytic acid’ or ‘high-available P’ (HAP) mutants when phytase supplementation was contained in diet. However, total activity of phytase was 35% higher in the small intestine of laying hens because of different pH. And both microbial phytase and lactic acid enhanced the apparent total tract digestibility (ATTD) of ash, Ca and Mg and apparent ileal digestibility (AID) of phytic acid.

The impact of mineral nutrition on winter barley yields while using mustard as a precursor crop

Effect of non-lethal low phytic acid mutations on grain yield and seed viability in rice

Phytate is the primary form of phosphorus found in mature cereal grain. This form of phosphorus is not available to monogastric animals due to a lack of the enzyme phytase in their digestive tract. Several barley low phytic acid (lpa) mutants have been identified that contain substantial decreases in seed phytate accompanied by concomitant increases in inorganic phosphorus. Seed homozygous for low phytic acid 1-1 (lpa1-1) or low phytic acid 2-1 (lpa2-1) has a 50% and 70% decrease in seed phytate respectively. These mutations were previously mapped to chromosomes 2HL and 7HL respectively. The RFLP marker ABC153 located in the same region of 2H was converted to a sequence-characterized-amplified-region (SCAR) marker. Segregation analysis of the CDC McGwire × Lp422 doubled haploid population confirmed linkage between the SCAR marker and the lpa1-1 locus with 15% recombination. A third low phytic acid mutant, M635, has a 75% decrease in phytate. This mutation was located to chromosome 1HL by linkage with an inter-simple sequence repeat (ISSR) based marker (LP75) identified through bulked-segregant analysis, and has been designated lpa3-1. Based on analysis of recombination between marker LP75 and low phytic acid in an additional mutant line M955 (95% phytate decrease), lpa3-1 and the mutation in M955 are in the same region on chromosome 1HL, and may be allelic.

Low phytic acid (LPA) soybean [Glycine max (L.) Merr] genotypes reduce indigestible PA in soybean seeds in order to improve feeding efficiency of mono- and agastric animals, but often exhibit low field emergence, resulting in reduced yield. In this study, four LPA soybean varieties with two different genetic backgrounds were studied to assess their emergence and yield characters under 12 seed treatment combinations including two broad-spectrum, preplant fungicides (i.e., ApronMaxx (mefenoxam: (R,S)-2-[(2,6-dimethylphenyl)-methoxyacetylamino]-propionic acid methyl ester; fludioxonil: 4-(2,2-difluoro-1,3-benzodioxol-4-yl)-1H-pyrrole-3-carbonitrile) and Rancona Summit (ipconazole: 2-[(4-chlorophenyl)methyl]-5-(1-methylethyl)-1-(1H-1,2,4-triazol-1-ylmethyl) cyclopentanol; metalaxyl: N-(methooxyacetyl)-N-(2,6-xylyl)-DL-alaninate)), osmotic priming, and MicroCel-E coating. Two normal-PA (NPA) varieties served as controls. Both irrigated and non-irrigated plots were planted in Blacksburg and Orange, Virginia, USA in 2014 and 2015. Results revealed that three seed treatments (fungicides Rancona Summit and ApronMaxx, as well as Priming + Rancona) significantly improved field emergence by 6.4–11.6% across all genotypes, compared with untreated seeds. Seed priming was negatively associated with emergence across LPA genotypes. Seed treatments did not increase the yield of any genotype. LPA genotypes containing mips or lpa1/lpa2 mutations, produced satisfactory emergence similar to NPA under certain soil and environmental conditions due to the interaction of genotype and environment. Effective seed treatments applied to LPA soybeans along with the successful development of LPA germplasm by soybean breeding programs, will increase use of LPA varieties by commercial soybean growers, ultimately improving animal nutrition while easing environmental impact.

Phytic acid (PA, myo-inositol-1,2,3,4,5,6-hexakis-phosphate) and its salt form (phytate) are the principal storage forms of phosphorus in cereal grains. Since PA and phytates cannot be efficiently digested by monogastric animals, the abundance of PA in cereal and legume grains causes nutritional and environmental problems. The present study aimed at developing breeder-friendly functional molecular markers of five low phytic acid (LPA) mutant alleles of three rice (Oryza sativa L.) genes: viz., XQZ-lpa (a 1,475-bp deletion) and KBNT-lpa (a C→T single nucleotide polymorphism [SNP]) of LOC_Os02g57400, Z9B-lpa (a 6-bp deletion) and MH-lpa (a 1-bp deletion) of LOC_Os04g55800, and XS-lpa (a C→T SNP) of LOC_Os03g04920. First, markers for gel-based length polymorphism analysis were developed: viz., two insertion–deletion markers for XQZ-lpa and Z9B-lpa, two cleaved amplified polymorphic sequence (CAPS) markers for KBNT-lpa and XS-lpa, and one derived CAPS marker for MH-lpa. Second, the high-resolution melting (HRM) curve analysis method was explored for distinguishing plants with wild-type (WT) and LPA alleles (except XQZ-lpa). Plants of genotypes with homozygous mutant allele and WT, and with heterozygous alleles, could be directly differentiated by HRM for KBNT-lpa, XS-lpa and MH-lpa; only heterozygous individuals could be directly distinguished from homozygous WT and mutant plants for Z9B-lpa. However, by adding 15 % WT DNA templates to test samples before PCR, amplicons of three genotypes of the Z9B-lpa allele could also be differentiated by HRM analysis. Third, it was demonstrated that these markers could be effectively used for marker-assisted selection of LPA rice, and breeding lines with two non-allelic LPA mutations were developed with PA contents significantly lower than their respective parental LPA lines. Taken together, the present study developed functional molecular markers for efficient selection of LPA plants and demonstrated that double mutant LPA lines with significantly lower PA levels than primary LPA mutants (with single mutations) could be developed by pyramiding two non-allelic LPA mutations.

Phosphorus in drainage water leaving the Everglades Agricultural Area (EAA) in southern Florida is alleged to be contributing to the accelerated eutrophication of Lake Okeechobee and the degradation of the Water Conservation Areas and the Everglades National Park ecosystems. Agricultural “best management practices” (BMPs) offer a means for achieving reductions in P in drainage water. Prior to developing and implementing BMPs, it is necessary to establish baseline EAA P concentrations. Baseline total P (TP) and total dissolved P (TDP) concentrations for various crop and field conditions in the EAA were determined. Thirty‐six 0.7‐ha plots were installed at four locations. Average TP and TDP concentrations were derived from 6 to 30 drainage events for each of five conditions between November 1988 and December 1989: sugarcane (Saccharum spp.), radish (Raphanus sativus L.), and cabbage (Brassica oleracea L.) production fields, flooded fallow fields, and drained fallow fields. Baseline TP and TDP concentrations for main farm canals and rainfall were also determined. Average TP concentrations ranged from 0.25 mg L−1 for radishes to 1.03 mg L−1 during the drain‐down of flooded fallow plots. Total dissolved P concentrations ranged from 48 to 80% of TP. Main farm canal TP concentrations averaged 0.16 mg L−1. Total P concentrations in rainfall averaged 0.07 mg L−1 Total P in drainage water during 1989 for sugarcane, cabbage, and drained fallow fields were 0.72, 1.38, and 0.59 kg ha−1, respectively. During the radish season, drainage water TP loading was 0.8 kg ha−1. Flooded fallow fields after radishes yielded a TP loading rate of 3.82 kg ha−1. Total P loading to the fields from rainfall averaged 0.70 kg ha−1. Total dissolved P loading rates ranged from 25 to 60% of TP. Potential areas for BMP development and implementation for P concentration and loading reduction in the EAA include drainage rate, volume, and timing management, fertilizer use reduction, and enhanced crop rotation strategies.

Phytic acid acts as the major storage form of phosphorus in plant seeds and is poorly digested by monogastric animals. The degradation of phytic acid in animal diets is necessary to overcome both environmental and nutritional issues. The enzyme 1D-myo-inositol 3-phosphate [Ins(3)P(1)] synthase (EC 5.5.1.4) catalyses the first step of myo-inositol biosynthesis and directs phytic acid biosynthesis in seeds. The rice Ins(3)P(1) synthase gene (RINO1) is highly expressed in developing seed embryos and in the aleurone layer, where phytic acid is synthesized and stored. In rice seeds, 18-kDa oleosin (Ole18) is expressed in a seed-specific manner, and its transcripts are restricted to the embryo and the aleurone layer. Therefore, to effectively suppress phytic acid biosynthesis, antisense RINO1 cDNA was expressed under the control of the Ole18 promoter, directing the same spatial pattern in seeds as RINO1 in transgenic rice plants. The generated transgenic rice plants showed strong 'low phytic acid' (lpa) phenotypes, in which seed phytic acid was reduced by 68% and free available phosphate was concomitantly increased. No negative effects on seed weight, germination or plant growth were observed. The available phosphate levels of the stable transgenic plants surpassed those of currently available rice lpa mutants.

Phytic acid consists of 65-80% of the total phosphorus (P) in cereal grains. Its salts are concentrated in the germ and aleurone layers, which are typically removed during milling. We hypothesize that concentrations of different types of P and minerals in milled products will be greatly altered in low phytic acid (lpa) barleys. Seeds of cv. Harrington (control) and four lpa isolines-lpa1-1, lpa2-1, lpa3-1, and M955-were abraded by a laboratory method into five surface layer and four remaining kernel fractions. Results show that phytic acid in the four lpa lines ranged from 75% to 5% of the control. The decrease in phytic acid P concentration was matched almost equally by an increase in inorganic P, so that the rest of P (the sum of all P-containing compounds other than phytic acid P and inorganic P) and total P levels remained relatively unchanged among the five genotypes. These trends were also observed for the processed fractions. The major mineral elements in barley seeds were P, K, Mg, S, and Ca, while minor ones were Fe, Zn, Mn, Cu, and Ba. All types of P and other minerals measured were generally concentrated in the outer layers of the grain. Although there were substantial differences in mineral contents of bran fractions among genotypes, the level of phytic acid P had little effect on mineral contents in whole or abraded kernels. One major exception was Fe, which had the highest level in all tissues of M955 genotype. The above findings were all confirmed by analyzing another set of barley samples grown in a different environment. Thus, in general, breeding lpa barleys does not lead to reduced mineral contents in whole grains or elevated mineral levels in milled products.

Nutrient limitations on microbial respiration in peat soils with different total phosphorus content

Low phytic acid (LPA) wheat (Triticum aestivum L.) is one approach to improving nutritional quality of wheat by reducing the major storage form of P and increasing the level of inorganic P (Pi), which is more readily absorbed by humans and other monogastric animals. A LPA mutant of wheat, designated Js‐12‐LPA was isolated following mutagenesis. LPA and wild‐type (WT) sib selections of hard red spring wheat families with the pedigree ‘Grandin’*4/Js‐12‐LPA were grown in replicated field trials in 2003 and 2004. Grain was milled on an experimental mill, and the distribution of P, phytic acid P (PAP), and Pi was measured in milling fractions. Mineral concentrations also were determined. LPA selections had elevated concentrations of Pi and Mg in flour fractions. The concentration of Pi in LPA flour was three times the concentration in WT flour, and Mg concentration in LPA flour was 25% greater than in WT flour. Therefore, P and Mg in LPA wheat appear to be redistributed within the kernel. The increase in Pi is similar to that observed for other LPA mutants and should improve the mineral nutrition of monogastric animals fed whole grain LPA wheat. As most wheat is milled for flour and bran, the detailed distribution of minerals in the LPA wheat should assist geneticists and nutritionists in assessing the value of this mutation.

Identification of low phytic acid and high Zn bioavailable rice (Oryza sativa L.) from 69 accessions of the world rice core collection

Low phytic acid (LPA) genotypes of wheat (Triticum aestivum L.) improve the nutritional quality of wheat by reducing the concentration of phytic acid (PA) in the aleurone layer, thus reducing the chelation of nutritionally important minerals and improving the bioavailability of phosphorus. Field studies were conducted at Aberdeen and Tetonia, ID, in 2003 and 2004 to evaluate the effects of the LPA genotype on the agronomic performance of wheat. These studies included wild‐type (WT) and LPA genotypes in hard red spring, hard white spring, and soft white spring wheat genetic backgrounds. In the hard red spring genetic background, LPA genotypes had delayed development and reduced grain yield (8–25%) in the high yield environment, in part due to reduced kernel size (up to 3 mg kernel−1). In the hard white spring genetic background, differences in crop development and grain yield were not observed; however, in the high yield environment LPA genotypes produced smaller kernels (2.0–2.4 mg kernel−1). In the soft white spring genetic background, LPA genotypes developed earlier, but the grain yield of LPA genotypes was reduced 20 to 24% in the high yield environment. However, LPA kernels, on average, were heavier and larger in diameter than WT kernels. The absence of consistent effects of the LPA genotype across the three genetic backgrounds suggests that deleterious effects of the LPA genotype may be mitigated by plant breeding.

Effect of Farming Practices on the Variability of Phosphorus Status in Intensively Managed Soils