The mobilization of macronutrient elements in the germinating wheat grain

Eastwood, David B.; Laidman, D. L.

doi:10.1016/s0031-9422(00)84328-9

Cited by 49 publications

(23 citation statements)

References 19 publications

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“…This is one of the possible controlling mechanisms for enzyme release postulated by Jones and Jacobsen [211 . The other regulatory mechanisms for enzymes release, by cell-wall breakdown and ion exchange between seed and medium [9,21 ] , are evident in our results (see acid phosphatase and phytase in Fig . 2) .…”

Section: Discussionsupporting

confidence: 54%

“…This suggests that the particular GAs could exert their action preferentially in a specific tissue . Furthermore, one cannot discount the possibility that an enzyme may be activated indirectly as a consequense of other events caused by GAs, as in the case of phytase action stimulated by phosphorous release, described by Eastwood and Laidman [9] .…”

Section: Discussionmentioning

confidence: 99%

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Gibberellin and abscisic acid effects on the activity of hydrolytic enzymes in de-embryonated barley seeds

1984

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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Gibberellin and abscisic acid effects on the activity of hydrolytic enzymes in de-embryonated barley seeds

1984

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“…The mobilization and transport of minerals within various tissues is obviously vital to the development of the embryo and has been demonstrated to be under hormonal control (Eastwood & Laidman, 1971;Mukhtar & Laidman, 1982). An important supplement to such studies is the quantification of the macro and trace elemental contents of the various anatomical structures within the seed which has usually relied on atomic absorption spectroscopy or other bulk analysis techniques (Garcia, Blessin & Inglett, 1972;Hill, Robson & Loneragan, 1979;Sokolov et al, 1981).…”

Section: Introductionmentioning

confidence: 99%

Quantitative Microanalysis of Mn, Zn and Other Elements in Mature Wheat Seed

1985

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SUMMARYA scanning proton microprobe has been used to determine quantitatively the distribution of Mn, Zn and other elements in the mature wheat seed {Triticum aestivum cv. Gamenya). Both X-ray and nuclear scattered proton data were collected during the irradiation of a 40/im-thick longitudinal section, and these were used to calculate absolute elemental concentrations for the various features of interest in the embryo region. Elemental maps were collected for a number of transverse and longitudinal sections (obtained from several seeds), but comprehensive analytical information was collected from one typical longitudinal section only. In the embryo, the concentration (by dry weight) of Mn was highest in the radicle (1400 +200/

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“…DISCUSSION The storage of phosphate and cations in a complex with myoinositol in cereal seeds is now widely accepted (4,7,12,15,16,18,25,26). In wheat, the mobilization of these elements is known to occur during germination when the embryo accumulates these ions at the expense of the aleurone layer (3). During the mobilization of these ions at least two processes can be distinguished.…”

Section: Resultsmentioning

confidence: 99%

“…That GA does not affect ion release by increasing phytase activity is also suggested by the work of Eastwood and Laidman (3) in wheat. These workers showed that when the embryo was replaced with GA an increase in ion efflux from wheat aleurone cells occurred without a concomitant increase in phytase activity (3). Experiments with inhibitors of oxidative phosphorylation also indicate that ion availability is not the regulator of ion release.…”

Section: Resultsmentioning

confidence: 99%

Gibberellic Acid and Ion Release from Barley Aleurone Tissue

Jones

1973

Plant Physiol.

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The release of potassium, magnesium, and phosphate ions from aleurone cells of barley (Hordeum vulgare L. cv. Himalaya) is a gibberellic acid-dependent process. The release of these ions is preceded by a lag period of 6 to 8 hours after gibberellic acid addition. The effect of gibberellic acid on the re. lease of ions is not mediated through an effect on ion solubilization. Thus, gibbereilic acid does not apreciably affect the sum of extracted and released ions relative to controls. Rather, the effect of the hormone is on the release process itself. Inhibitors of oxidative phosphorylation when added with gibberellic acid or at times up to 6 hours after gibberellic acid inhibition release. When these inhibitors are added after ion release has begun, however, rapid efflux of ions occurs. These results suggest a strong correlation between energy levels and ion transport capacity. Inhibitors of RNA and protein synthesis also inhibit gibberellic acid-stimulated ion release. Evidence suggests that RNA and protein synthesis are required to establish and maintain ion release capacity of aleurone cells.The GA enhancement of hydrolytic enzyme synthesis at the expense of reserve proteins in aleurone layers of barley is firmly established (17,24,27 Phytin (Ca, Mg salt of inositol hexaphosphate) is presumed to be the principle reserve of phosphorous, magnesium, calcium, and possibly potassium in cereal seeds (16,21,25). In barley, phytin contains about one-half of the total phosphorous present in the seed (7). Whether calcium and magnesium ions are always associated with phytin is in question (22). Sandegren (22) reported that in mature barley grain, phytin exists as the water-soluble sodium-potassium salt which, after steeping, undergoes conversion to the insoluble calcium-magnesium salt by ion-exchange.In wheat most of the phytin of the grain is located in the aleurone layer (15). Similarly, as much as 60% of the inorganic ions of the seed are found in this tissue (9). A definitive analysis of the distribution of phytin and inorganic ions has not been made in barley. Phytin does, however, occur in aleurone cells of barley as shown by the presence within protein bodies of distinct electron dense globoids (4,10,12,18).During malting of barley, an 8-fold increase is found in the level of phytase, the enzyme responsible for the hydrolysis of phytin to myoinositol and inorganic phosphate (7). De-embryonated half seeds of barley also possess phytase activity which, as in wheat, is mostly in the aleurone layer (19,20,23). GA treatment increases phytase activity in half seeds of barley; however, the effect of GA is low when compared with its effects on other hydrolases (2, 23). Since a large proportion of the phosphate, magnesium, and calcium of the barley seed may be present in phytin, the redistribution of these elements would be dependent on the hydrolysis of phytin by phytase and the subsequent release of these elements from the aleurone cell (25,26).In experiments reported in this paper, emphasis has been placed on th...

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The mobilization of macronutrient elements in the germinating wheat grain

Cited by 49 publications

References 19 publications

Gibberellin and abscisic acid effects on the activity of hydrolytic enzymes in de-embryonated barley seeds

Gibberellin and abscisic acid effects on the activity of hydrolytic enzymes in de-embryonated barley seeds

Quantitative Microanalysis of Mn, Zn and Other Elements in Mature Wheat Seed

Gibberellic Acid and Ion Release from Barley Aleurone Tissue

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