John N. A. Lott

Phytic acid and phosphorus in crop seeds and fruits: a global estimate.

A very important mineral storage compound in seeds is phytate, a mixed cation salt of phytic acid (myo-inositol hexakis phosphoric acid). This compound is important for several reasons: (1) It is vital for seed/grain development and successful seedling growth. (2) It is often considered to be an antinutritional substance in human diets, but it may have a positivenutritional role as an anti-oxidant and an anti-cancer agent. (3) It represents a very significant amount of phosphorus being extracted from soilsand subsequently removed with the crop. (4) It plays a role in eutrophication of waterways. A key part of this review is an estimate of the annualtonnage of phosphorus and phytic acid sequestered in up to 4.1 billion metric tonnes of crop seeds and fruits globally each year. We estimate thatnearly 35 million metric tonnes of phytic acid, containing 9.9 million metric tonnes of P, is combined with about 12.5 and 3.9 million metric tonnes of K and Mg respectively, to form each year over 51 million metric tonnes of phytate. The amount of P inthis phytate is equal to nearly 65÷ of the elemental P sold world wide for use in mineral fertilizers. Dry cereal grains account for 69÷ of the total crop seed/fruit production but account for 77÷ of the total phytic acid stored each year. Low phytate mutants, that are now available for some key staple food crops such as maize and barley, offer potential benefits in such areas as the sustainability of lands used to grow crops, the mineral nutrition of humans and animals, and reduction in pollution of waterways.

Formation of pore-filled ion-exchange membranes with in situ crosslinking: Poly(vinylbenzyl ammonium salt)-filled membranes

Robust, polyelectrolyte-filled, microporous membranes were prepared by the introduction and crosslinking of a preformed polymer within the pores of a poly(propylene) host membrane. Specifically, poly(vinylbenzyl chloride) (PVBCl) was reacted with piperazine or 1,4-diaminobicyclo[2.2.2]octane in an N,N-dimethylformamide (DMF) solution contained in the pores of the microporous base membrane. The remaining chloromethyl groups were reacted with an amine, such as trimethylamine, to form positively charged ammonium sites. This simple two-step procedure gave dimensionally stable, anion-exchange membranes in which the degree of crosslinking and the mass loading were determined by the concentration of PVBCl and crosslinker in the starting DMF solution. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes are fully characterized.

Poly(4-vinylpyridine)-filled microfiltration membranes: physicochemical properties and morphology

Abstract The morphology and physicochemical properties of poly(4-vinylpyridine)-filled microfiltration membranes have been examined. These membranes, which were prepared by photoinitiated grafting of up to 125 mass% of 4-vinylpyridine into the pores of polypropylene (PP) microfiltration membranes, were characterized in terms of the amount of poly(4-vinylpyridine) incorporated (graft yield), ion-exchange capacity, water content, and thickness. The morphology of samples of the grafted membranes dehydrated by freeze substitution was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. While the ion-exchange capacities of the grafted membranes are a function of graft yield, ranging to 4.0 meq/g of dry membrane, the water contents of the grafted membranes in the free base form are essentially independent of graft yield. The porosity of the grafted membranes was shown to be almost the same as that of the starting base polypropylene membranes (60–80%). However, protonation of the grafted poly(4-vinylpyridine) was shown to lead to a further and very substantial increase of the void volume of the membranes as measured by their water content. The thickness of the grafted membranes was found to increase linearly with increasing incorporation of polyvinylpyridine. Ionization of the polyelectrolyte was shown to cause a further systematic increase in thickness which was partly reversible with reversion to the unprotonated form. These changes in thickness are attributed to the stretching of the mesh of the substrate microfiltration membranes.

A review of the phosphorus content of dry cereal and legume crops of the world

When food scarcity increases, instability in society increases. The majority of food consumed is from cereals and legumes. Phosphorus is essential for crop plant growth and soils are depleted as this element is removed from crop lands with harvested grains/seeds. To sustain yields, inputs of nutrients are required to balance losses. On global and continental/regional bases, we assembled nine years data on: total dry cereal grain and total dry legume seed production, production of barley, maize, rice, soybean and wheat grains/seeds, yields, area farmed, the tonnage of phosphorus and phytic acid removed in these crops and the elemental phosphorus applied as mineral fertilizers to all plant crops. Some significant imbalances were found that may affect food security. Asia consumes significantly more mineral P fertilizer in proportion to crop production than any other region – a potential environmental, economic and social problem. Approaches which could address nutrient (P) imbalances are discussed.

Leakage of K, Mg, Cl, Ca and Mn from imbibing seeds, grains and isolated seed parts

Instrumental neutron activation analysis (NAA) was used to quantify the amounts of K, Mg, Cl, Ca and Mn leaked into water from imbibing dry seeds, dry fruits and isolated seed parts. A number of intact monocot and dicot dry seeds or fruits were studied as were some isolated parts such as testa, endosperm and embryo. All samples studied leaked detectable amounts of the five elements measured but the amounts leaked varied greatly. In most cases K was leaked in greater amounts than the other elements while Mn was leaked least. The leakage of Ca was highest from isolated seed coats and from mericarps of three umbelliferous species. Comparisons of the amount of element leaked with the total amount of that element present in the starting material showed that leakage, especially of K, represents a substantial loss of mineral nutrient reserves. The degree of leakage of elements did not appear to be closely related to the types of organic storage reserves present.

Changes in the cotyledons ofCucurbita maxima during germination

SummaryThe ultrastructural changes occurring in cotyledon protein bodies of germinating squash seeds were investigated using mainly the freeze-etching technique. The appearance and subsequent disappearance of soft globoid-like material in the proteinaceous matrix was documented as the first major ultrastructural change. The globoid crystal was digested either by the formation of internal pitted regions or through external digestion. During later stages of breakdown the protein bodies became a series of largely aqueous vacuoles containing irregularly shaped pieces of protein material. This protein material eventually disappeared and the vacuoles fused to form the central vacuole of the mesophyll cells. This fusion of vacuoles was followed in living cells using Nomarski optics.

Mineral nutrition in white spruce (Picea glauca [Moench] Voss) seeds and somatic embryos. I. phosphorus, phytic acid, potassium, magnesium, calcium, iron and zinc

Abstract The mineral nutrient storage reserves in white spruce ( Picea glauca [Moench] Voss) somatic embryos and various parts of white spruce seeds were investigated. Somatic embryos are embryos produced in tissue culture. A single somatic embryo or zygotic embryo contained similar amounts of P and both types of embryos had similar amounts of the total P present in phytic acid (PA). The large female gametophyte tissue, which is absent in a somatic embryo, contained 86% of the total P and 95% of the total phytic acid-phosphorus (PA-P) in a single seed. The female gametophyte of a single seed contained ≈7 times more P and ≈22 times more PA-P than a single zygotic embryo. Somatic and zygotic embryos had significantly less of their P present in PA than did the female gametophyte tissue, which has over 87% of its P present in PA. A single somatic embryo or zygotic embryo contained similar amounts of K, Mg, Ca, Fe and Zn. The female gametophyte tissue contained 59% of the K, 85% of the Mg, 28% of the Ca, 69% of the Fe, and 65% of the Zn in a single seed. The seed coat of a single seed contained the majority of a seed’s Ca (71%) and also contained significant levels of K, Fe and Zn. On a dry weight (DW) basis, differences were found in the amounts of all the mineral nutrients studied here because somatic embryos are larger than zygotic embryos. Overall, a white spruce somatic embryo has equivalent amounts of all these nutrients as found in a natural white spruce zygotic embryo.

Mineral nutrition in White Spruce (Picea glauca [Moench] Voss) seeds and somatic embryos; II. EDX analysis of globoids and Fe-rich particles

Abstract The elemental compositions of globoids and Fe-rich particles were investigated in white spruce ( Picea glauca [Moench] Voss) somatic embryos, zygotic embryos and female gametophytes using energy dispersive X-ray analysis. Globoids, phytate deposits in seed protein bodies, were found throughout the female gametophyte of seeds and in the ground meristem and procambium from all regions of both somatic and zygotic embryos. Iron-rich particles, believed to be Fe-associated phytate deposits in seed proplastids, were found throughout the female gametophyte of seeds and in the protoderm, ground meristem, and procambium from all regions of both somatic and zygotic embryos. Globoids in somatic and zygotic embryos ranged from 0.5–3.0 μm in diameter, but globoids typically ranged from 1.5–52.0 μm in diameter in somatic embryos and from 2.0–3.0 μm in diameter in zygotic embryos. Globoids in female gametophyte tissue ranged from 0.5–6.0 μm in diameter. All Fe-rich particles studied from somatic embryos and from seeds ranged from 0.14–0.25 μm in diameter. Globoids in somatic embryos and seeds contained high P, moderate K and Mg with occasional traces of Fe and little if any Ca and Zn. Globoids in the zygotic embryo cotyledon procambium tissue also contained moderate levels of Fe and had significantly higher Fe:P ratios, which were not found in any other regions in seeds or in somatic embryos. Iron-rich particles in somatic embryos and seeds contained high P and Fe, moderate K and Mg, and little if any Ca and Zn. Typically, spectra of Fe-rich particles in somatic embryos had P peaks higher than Fe peaks and spectra of Fe-rich particles in seeds had P peaks lower than Fe peaks. Overall, the composition of globoids and Fe-rich particles in somatic embryos and zygotic embryos were very similar with only minimal differences found.

THE CELL WALL OF COSMARIUM BOTRYTIS12

The cell wall of Cosmarium botrytis was studied through the use of the freeze‐etch technique. The cell wall consists of many thin layers. Fracturing along one layer reveals the positioning of the wall sculpturing, wall pores, and wall microfibrils. The individual microfibrils are grouped together in bands of parallel oriented fibrils. The different bands of parallel microfibrils were apparently arranged at random angles with regard to each other. Small particles may also be present in the cell walls.

IRON-RICH PARTICLES IN EMBRYOS OF SEEDS FROM THE FAMILY PINACEAE

SummaryIron-rich particles, previously reported in seeds of members of the genus Pinus, were found in radicle-hypocotyl tissues of dry embryos from eight other genera in the family Pinaceae. Thus, these Fe-rich particles are of common occurrence in seeds of this conifer family. These particles were most difficult to locate inPseudolarix amabilis, which has green embryos. Energy-dispersive X-ray analysis was used to determine the elements present in conifer Fe-rich particles and phytoferritin deposits in pea embryo axes. Ferich particles from all species studied contained mainly Fe and P but also contained considerable K and Mg. Abietoideae group I (genera Cedrus andAbies) had lower Fe ∶ P ratios compared to all the other combined subfamilies within the Pinaceae. Pea phytoferritin deposits contained markedly lower amounts of P relative to Fe based on peakto-background ratios and quantitative values calculated by using a ferric phosphate standard. We also found, for the first time, that pea phytoferritin contained considerable K. A strong similarity was found between the energy-dispersive X-ray analysis spectra from Ferich particles and portions of a laboratory-synthesized Fe, K, Mg phytate salt. Phytate is a common mineral-nutrient storage compound in seeds. The possibility of these Fe-rich particles being phytoferritin cannot be ruled out, but if they are phytoferritin, they have lower Fe ∶ P ratios than almost all other ferritins reported to date.