The ultrastructure of germinating barley seeds. I. Changes in the scutellum and the aleurone layer in Nordal barley

Gram, Niels H.

doi:10.1007/bf02914032

Cited by 39 publications

(21 citation statements)

References 44 publications

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“…The abundant stacks and arrays of RER of the active aleurone cells observed at the EM level had an appearance and location similar to those of the fluorescence produced by DiOC6(3) staining, which leads us to believe that this fluorescence represents mainly ER in these cells. These structural and ultrastructural changes observed in the aleurone cells of Funks G4646 and Illinois 677a are similar to what has been described in germinating barley grains (11), and these changes have been functionally correlated with the synthesis and secretion of hydrolases, including a-amylase (14). The proliferation of RER and numerous dictyosomes in particular suggests that the endomembrane system plays a key role in a-amylase synthesis and secretion (8,15).…”

Section: Discussionsupporting

confidence: 72%

Characteristics of α-Amylase during Germination of Two High-Sugar Sweet Corn Cultivars of Zea mays L.

Sanwo¹,

DeMason²

1992

Plant Physiol.

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The role of the scutellum and the aleurone in a-amylase production in the high-sugar sweet corn cultivars Illini X-tra Sweet (shrunken-2, sh2) and Illinois 677a (sugary, sugary enhancer; su se) was compared to that in the starchy (Su) hybrid Funks G4646 with the use of a-amylase enzyme assays, isoelectric focusing, electron microscopy, and laser scanning confocal microscopy. The scutellum of Illinois 677a had low levels of a-amylase activity compared to that of Funks G4646 through 10 days after imbibition, and the aleurone of Illini X-tra Sweet had negligible activity. On the isoelectric focusing gels, the Illinois 677a scutellum had fewer a-amylase isozymes at 7 days compared to the Funks G4646 scutellum. The Illini X-tra Sweet aleurone had no a-amylase isozymes. Funks G4646 scutellar epithelial and aleurone cells contained abundant rough endoplasmic reticulum, polysomes, and dictyosomes at 5 and 7 days, respectively. The scutellar epithelial cells of Illinois 677a contained fewer of these structures by 5 days, and the Illini X-tra Sweet aleurone contained mostly lipid bodies through 7 days. Few cytoplasmic membranes and little RNA were detected with laser scanning confocal microscopy in the Illini X-tra Sweet aleurone compared to Funks G4646 at 7 days. These data suggest that the scutellum of Illinois 677a and the aleurone of Illini X-tra Sweet have impaired abilities to produce a-amylase.The main storage products in cereal grains are carbohydrates, specifically amylose and amylopectin (1). During germination, the principle enzyme involved in carbohydrate breakdown is a-amylase, which hydrolyzes a(1-4) bonds in amylose and amylopectin, releasing fragments that can be further broken down by ,B-amylase, a-glucosidase, and debranching enzymes. a-Amylase is synthesized de novo in two specific tissues of the cereal grain, the scutellar epithelium of the embryo and the aleurone layer of the endosperm (1

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Section: Discussionsupporting

confidence: 72%

Characteristics of α-Amylase during Germination of Two High-Sugar Sweet Corn Cultivars of Zea mays L.

Sanwo¹,

DeMason²

1992

Plant Physiol.

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“…In malting barley and other germinating cereal grains, it has been established that features indicating cellular activity, and production of hydrolases and amylases, are initiated in the scutellum followed by the aleurone layer, and that degradation of endosperm cells starts in the vicinity of the scutellum. [9][10][11] Intact oil bodies thought essential for optimal germination conditions are challenged by their fused state in storage tissues of the oat endosperm. The implications of their fusion for germination and end use quality remain to be determined.…”

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confidence: 99%

The distribution of oil in the oat grain

Heneen

Banaś

Леонова

et al. 2009

Plant Signaling & Behavior

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High-lipid oat is a potential oil crop. Chemical and microscopical analyses have shown that the major part of the grain lipids are stored in the endosperm. While oil bodies are intact in the aleurone layer, scutellum and embryo, they have less associated proteins (oleosins) and undergo fusion in the starchy endosperm. In this report, we document the distribution of lipids in the endosperm microscopically. Underneath the aleurone layer, lipids are most abundant in the subaleurone cells and in the endosperm cells in the vicinity of the scutellum and embryo. Thus the major areas of oil storage are close to the living tissues of the grain, the sites of enzyme production in connection with germination and mobilization. The documentation of cellular structural changes, and implication of the fused state of oil bodies, during germination, remains to be elucidated.Oat (Avena sativa L.) is a cereal crop that accumulates up to 18% of lipids. 1 Most of the lipids are stored in the endosperm tissues of the grain. [2][3][4] This has been also demonstrated using fluorescence microscopy, 1,5 light microscopy as well as scanning and transmission electron microscopy. 4,6 White et al., 7 on the other hand, interpreted their transmission electron microscopy pictures as if indicating scarcity or absence of lipids beneath the subaleurone layer. Applying different microscopical approaches, it has been shown that oil bodies appear as distinct entities in the embryonic axis and the aleurone layer, and that they loose their integrity and fuse with each other into large masses in the rest of the endosperm during grain development. 6 The fusion of oil bodies in the starchy endosperm is probably correlated with the reduced amount of the protecting oil-body associated proteins (oleosins) documented in this tissue. 6 The aim of this report is to present microscopical data on the distribution of oil throughout the oat endosperm, not shown in Heneen et al. 6 The structural observations were made on the highlipid oat cultivar Matilda with 10.3% lipids. 6 Sectioned sectors of grains at early and late developmental stages, 14 and 40 days after anthesis, were stained with Sudan Black B or Toluidine Blue O. 6 The low magnifications of whole sectors of the grain and higher magnifications of defined sites (Fig. 1) provide information on the distribution and appearance of lipids throughout the grain. A further step would be simultaneous visualization and quantification of lipids, as has been elegantly demonstrated in developing barley grains and soybean seeds in vivo, applying frequency-selected magnetic resonance imaging. 8 At the early developmental stage of oat grains (Fig. 1A), lipids were less densely stained in the aleurone layer than in the rest of the endosperm, inferring tissue-specific differences. Oil was not evenly distributed in the starchy endosperm. It was most frequent in the subaleurone cells, and decreased in cells of middle and inner endosperm, in accordance with earlier findings. 5 This was valid for the discrete oil bodies observe...

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“…In rice, however, newly formed plastids in endosperm contained multiple starch granules. On the other hand, Gram (1982) reported that lipid bodies decrease in number and become smaller in size during germination, while mitochondria develop well, which are thought to be the characteristics of the high metabolic activity. Figure 15 shows a high magnification of a newly formed plastid adjacent to the cell wall.…”

Section: Scanning Electron Microscopic Observationmentioning

confidence: 99%

Effect of Temperature on the Decomposition of Reserves during Germination and Early Growth of Rice Plants

Zakaria

Matsuda

Nitta

2001

Plant Production Science

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The ultrastructure of germinating barley seeds. I. Changes in the scutellum and the aleurone layer in Nordal barley

Cited by 39 publications

References 44 publications

Characteristics of α-Amylase during Germination of Two High-Sugar Sweet Corn Cultivars of Zea mays L.

Characteristics of α-Amylase during Germination of Two High-Sugar Sweet Corn Cultivars of Zea mays L.

The distribution of oil in the oat grain

Effect of Temperature on the Decomposition of Reserves during Germination and Early Growth of Rice Plants

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