Mineral Reserves in Castor Beans: The Dry Seed

Lott, John N. A.; Greenwood, John S.; Vollmer, Catherine M.

doi:10.1104/pp.69.4.829

Cited by 30 publications

(14 citation statements)

References 20 publications

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“…Globoid crystals from the radicle had considerable variability of elemental composition in all investigated species. Besides P, K. Mg, and Ca, the presence of other elements (Mn, Fe, and Bal was described (Lott and Buttrose, 1978;Spitzer and Lott, 1980;Lott et al, 1982). In this study, GCs rich in Zn were found in maize radicle and coleorhiza.…”

Section: Results Of Our Edx Analyses Of Scutellarsupporting

confidence: 49%

Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (Zea mays L.)

1992

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Protein bodies (PBs) from the epidermis and cortex of the radicle, as well as from coleorhizal and scutellar parenchyma of dry maize seeds were studied with the emphasis on presence and elemental composition of globoid crystals. PBs with variable structure were found in investigated tissues. Radicular epidermis was the only investigated tissue containing structurally uniform populations of PBs. They were filled by a homogeneous matrix without globoid crystals or their remnants. PBs structure and amount of proteinaceous matrix varied in the same cell of coleorhiza and scutellum. In the case of radicular cortex, the structure of PBs differed between analyzed individuals. Globoid crystals of various sizes were found in PBs from scutellum, coleorhiza, and from inner layers of radicular cortex. The largest globoid crystals (up to 2.0 μ in diameter) were seen in the scutellum. Energy‐dispersive X‐ray microanalysis revealed the presence of P,K. Mg, and some traces of Fe and Zn in the majority of globoid crystals from the scutellum. Globoid crystals from coleorhiza and radicular cortex were rich in Zn and Ca. The presence of considerable Zn was usually accompanied by high Ca, at the expense of K and Mg. As EDX analyses revealed significant differences in Zn and Zn/P values between analyzed tissues, it is probable that the majority of Zn is preferably accumulated in globoid crystals of some tissues of maize germ.

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Section: Results Of Our Edx Analyses Of Scutellarsupporting

confidence: 49%

Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (Zea mays L.)

1992

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“…Phytate is considered to function as a reserve of phosphorus and various cations mainly in seeds (Cosgrove, 1980), but it has also been detected in roots (Campbell et al, 1991). The principle minerals stored as phytate are potassium and magnesium (Lott et al, 1982), but also copper, zinc, iron, and calcium (Maga, 1982;MikuS et al, 1992). Van Steveninck et al (1990) discuss the binding of excess zinc by phytate as a possible detoxification mechanism, especially in zinc-tolerant plants, but Mossbauer studies of iron in tomato plants showed that the ferric component in tomato seeds is different from those of phytate (Ambe, 1989).…”

Section: Discussionmentioning

confidence: 99%

Subcellular Localization and Characterization of Excessive Iron in the Nicotianamine-less Tomato Mutant chloronerva

1995

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To understand the function of the Fe2+-complexing compound nicotianamine (NA) in the iron metabolism of plants we have localized iron and other elements in the NA-containing tomato wild type (Lycopersicon esculentum) and its NA-free mutant chloronerva by quantitative x-ray microanalysis. Comparison of element composition of the rhizodermal cell walls indicated that the wild type accumulated considerable amounts of iron and phosphorus in the cell wall, whereas in the mutant iron and phosphorus were detected in the cytoplasm and vacuoles of the rhizodermis. In mutant leaves containing high iron concentrations in the symplast, electron-dense inclusions were detected in chloroplasts and phloem. Such particles, consisting mainly of iron and phosphorus, were never found in the wild type and were very rarely detected in young chlorotic mutant leaves or after treatment of the mutant with NA. For further characterization the electron-dense inclusions in mutant leaves were isolated and compared by sodium dodecyl sulfate-gel electrophoresis and immunoblotting to ferritin from iron-loaded Phaseolus vulgaris leaves. Antibodies raised against purified Phaseolus leaf ferritin were used. Neither in mutant nor in wild type (iron loaded and control) was ferritin protein detected. These results suggest that the electron-dense inclusions in mutant leaves are not identical with ferritin. It is concluded that NA is necessary to complex ferrous iron in a soluble and available form within the cells. In the absence of NA the precipitation of excessive iron in the form of insoluble ferric phosphate compounds could protect the cells from iron overload.

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“…The high amounts of magnesium in the Ricinus cotyledon (100 200 p~mol, g FW 1) are most likely deposited in the form of globoid phytinate crystals (Lott et al 1982). As a consequence of this high endogenous magnesium content it was not possible to study phloem transport under conditions of magnesium deficiency, and even 9 h of exudation from endosperm-free seedlings did not lead to an appreciable decrease in the magnesium concentration of the sieve-tube sap.…”

Section: Discussionmentioning

confidence: 99%

Transport of magnesium ions in the phloem of Ricinus communis L. seedlings

Zhong

Schobert

Komor

1993

Planta

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Abstract. During growth of Ricinus communis seedlings, magnesium ions are mobilized in the endosperm, taken up by and accumulated to very high levels (150 ~tmol.g FW 1) in the cotyledons, and translocated to hypocotyl and roots. The magnesium gain from days 6 to 7 in the cotyledons and the seedling axis necessitates a total uptake rate of 600 nmol.h 1.seedling--1 and the phloem translocation rate must amount to 200nmol.h ~. seedling 1. The phloem loading of magnesium and the regulatory properties of this process were investigated, making specific use of the ability to collect pure phloem sap from the cut hypocotyl of 6-d-old Ricinus seedlings. The concentration of magnesium in sieve-tube sap (5 mM) was fairly constant under many incubation conditions, e.g. incubation in magnesium-free buffer, incubation with different cations (K +, Na +, NH~-) or anions (C1 , NO3-, SO] ), or incubation with sucrose and amino acids. Even addition of magnesium chloride to the cotyledons did not enhance phloem loading of magnesium ions. Therefore the high magnesium content of the cotyledons was sufficient for continuous phloem loading of magnesium, irrespective of external ionic conditions. Also, the flow rate of sieve-tube sap did not influence the magnesium concentration in the sap. Only the incubation with sulfate and phosphate ions increased the magnesium-ion concentration in the phloem. Magnesium sulfate offered to the cotyledons caused a threefold increase of magnesium ions in the sieve-tube sap, which was inhibited by Na +, NH + and Ca 2+ in rising order, but not by K +. Incubation with phosphate for a prolonged period (8 h) led to an increased mobilization of intra-cotyledonary magnesium and an enhanced phloem loading of mobilized magnesium. It is concluded that phosphate availability is a decisive factor for mobilization and translocation of magnesium ions within the plant.

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Mineral Reserves in Castor Beans: The Dry Seed

Cited by 30 publications

References 20 publications

Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (Zea mays L.)

Structure of Protein Bodies and Elemental Composition of Phytin from Dry Germ of Maize (Zea mays L.)

Subcellular Localization and Characterization of Excessive Iron in the Nicotianamine-less Tomato Mutant chloronerva

Transport of magnesium ions in the phloem of Ricinus communis L. seedlings

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