Phytic acid-phosphorus and other nutritionally important mineral nutrient elements in grains of wild-type and low phytic acid (lpa1–1) rice

Abstract

2004). Phytic acid-phosphorus and other nutritionally important mineral nutrient elements in grains of wild-type and low phytic acid (lpa1-1) rice. AbstractMineral nutrient stores in cereal grains are mainly phytate, a salt of the phosphorus-rich compound phytic acid. Quantitative measures of total phosphorus, phytic acid-phosphorus, potassium, magnesium, calcium, iron, manganese and zinc were obtained for whole grains, embryos and rest-of-grain portions of cv. Kaybonnet rice (wild type) (Oryza sativa L.) and a low phytic acid (lpa1-1) mutant strain with a 45% reduction in phytic acid. P, K and Mg were present in higher amounts than Ca, Mn, Fe and Zn in both grain types. Whole-grain amounts of total P, Ca, Mn and phytic acid-phosphorus were lower in whole lpa1-1 grains than in wild-type grains; K, Mg and Fe amounts were similar, and Zn was higher. Embryos, which comprise 3.5% or less of grain dry weight, were comparatively rich in all measured elements. The lpa1-1 mutation influenced the phytic acid content of the embryo more than that of the aleurone layer. Aleurone-layer cells of wild-type grains had many phosphorus-rich globoids 2 µm or larger in diameter, whereas lpa1-1 grains contained more of the smaller globoids. The reduction in globoid size was consistent with the reduction in phytate. Energy-dispersive X-ray analysis of both aleurone-layer cells and sections of globoids in aleurone-layer cells revealed that P, K and Mg were the main mineral nutrient elements present in both grain types; traces of Ca, Mn, Fe or Zn were present. Starchy endosperm cells contained virtually no P, K or Mg, whereas scutellum cells were rich in these elements. Phytic acid-phosphorus in rice 113 Figure 1. Environmental scanning electron microscope (ESEM) micrographs of the aleurone layer from wild-type (a and c) and lpa1-1 (b and d) mature rice grains. Globoids are the light spheres. Scale bars: (a, b) 10 m; (c, d) 2 m.

Characterization of 68Zn uptake, translocation, and accumulation into developing grains and young leaves of high Zn-density rice genotype

“…It accumulates rapidly during seed development and can account for up to several percent of the seed DW (Lott, 1984). In this study, P accumulation in the grains of IR64 was higher than that of IR68144 during the grain filling stage, which was consistent with the result of Liu et al (2004). The content of Fe in developing grains was also analyzed (Fig.…”

Phytate: impact on environment and human nutrition. A challenge for molecular breeding

“…In wildtype (WT) wheat, globoids up to 4 μm in diameter have been detected (Antoine et al, 2004), whereas a low phytic acid (lpa) wheat mutant (Js-12-LPA) with the same amount of P in the grains but lowered phytate concentration has smaller globoids, organised in clusters (Joyce et al, 2005). This phenomenon has also been observed in WT wheat grown under low P conditions (Batten and Lott, 1986) and in lpa mutations in other cereals, such as rice (Liu et al, 2004), maize (Lin et al, 2005) and barley (Ockenden et al, 2004).…”

“…Reducing phytate content through lpa mutants have been attempted through knock-out of genes involved in PA biosynthesis. With the only exception of one barley mutant accumulating Fe, the mineral composition does not dramatically change in lpa mutants, indicating that there is no direct link between mineral distribution and phytic acid biosynthesis (Joyce et al, 2005;Liu J.C. et al, 2004;Liu K. et al, 2007;Ockenden et al, 2004). Chicks fed lpa barley or corn, respectively excrete 33% less phosphate and they show enhanced growth and bone structure (Jang et al, 2003) as compared to chicks on a normal diet.…”

Instability of endosperm development in amphiploids and their parental species in the genus Avena L.

“…Here, the distance between the aleurone cells and vascular tissues can determine the support of globoid components. In cereals, some mutants with numerous small globoids are known; for example, a low phytic acid mutant has been reported for Oryza sativa (Liu et al 2004), Hordeum vulgare (Ockenden et al 2001), and Triticum eastivum (Joyce et al 2005). …”