Starch Granules In Endosperm Research Articles

A survey of endosperm starch granules in the genus Hordeum: a study using image analytic and numerical taxonomic techniques

Image analysis was used to quantify size of endospermic starch granules in 39 species of Hordeum. A set of 279 samples, each with ca. 25 replicates, representing most species of the genus was analyzed by various multivariate techniques. Two groups can be distinguished. One group consisting of 6 species (H. vulgare, H. spontaneum, H. bulbosum, H. glaucum, H. murinum, and H. leporinum) is characterized by possessing granules greater than 35 μm in diameter and a bimodal distribution of all the sizes. The second group, consisting of the remaining 33 species, had granules less than 35 μm in diameter, unimodally size distributed. Univariate statistics for each species are summarized in box plots and bar diagrams. Some species can be uniquely identified. The usefulness of starch in Hordeum systematics is discussed.

The Number and Sizes of Starch Granules in the Wheat Endosperm, and their Association with Grain Weight

The Number and Sizes of Starch Granules in the Wheat Endosperm, and their Association with Grain Weight

Effects of the barley mutants Risø 1508 and 527 high lysine genes on the cellular development of the endosperm

The dry grain weight of the Risø barley (Hordeum vulgare L. var. disticum) high lysine mutants 1508 and 527 at maturity was 32 and 37% lower, respectively, than the grains of the cultivar Bomi. Dry grain weight of the double mutant 527/1508 was reduced by 57%. Total number of endosperm nuclei from cv. Bomi, mutants 1508, 527 and 527/1508 at 24 days after anthesis was 173 000,156 000,121 000 and 111 000, respectively. Transverse mid‐grain sections from mutants 1508 and 527 contained fewer aleurone cells and approximately the same number of starchy endosperm cells as cv. Bomi. The cellular organization of the endosperm of the double mutant deviated substantially from the normal. Cell volume in the central starchy endosperm of cv. Bomi, mutants 1508 and 527 at 33 days after anthesis averaged 390 000, 270 000 and 180 000 um5, respectively. Cell volume in the double mutant was smaller than in 527, but could not be accurately estimated due to the irregular shape of the cells. The mean section area of individual large starch granules in the central endosperm of mutants 1508, 527 and 527/1508 at 33 days after anthesis was 30, 48 and 72% smaller, respectively, than those of cv. Bomi. The average aleurone cell volume in cv. Bomi at 33 days after anthesis was 6 200 μm3.

Conversion of free ?-amylase to bound ?-amylase on starch granules in the barley endosperm during desiccation phase of seed development

Association of β-amylase with starch granules in the starchy endosperm of barley (Hordeum vulgare L. cv. Menuet) grains was characterized biochemically. In whole homogenates of dry seeds, two forms of β-amylase were detected: one is free β-amylase extractable with saline solution and the other is bound β-amylase extractable with saline solution containing a reducing agent. The two forms of β-amylase were shown to be identical in terms of mobility on disc gels, antigenicity, and molecular specific activity, indicating that the β-amylase molecules of the two forms are identical. The starch granules were isolated from either dry seeds or mature seeds harvested before the desiccation phase. Both starch granule preparations were morphologically identical by microscopic inspection. The bound β-amylase was predominantly associated with starch granules isolated from dry seeds, whereas it was not associated with starch granules from mature seeds harvested before desiccation. Overall results show that the periphery of starch granules is the major site of deposition for bound β-amylase in dry seeds. The association of β-amylase with starch granules occurs during the desiccation phase of seed development, resulting in the conversion of free β-amylase into a bound form.

The relationship between A-type and B-type starch granules in the developing endosperm of wheat

The relationship between A- and B-type starch granules in the inner endosperm of some developing tetraploid and hexaploid wheats was examined by electron microscopy. At about 14 days after anthesis, B-type granules were initiated in the stroma of some A-type amyloplasts, often in association with the peripheral groove and tubuli. B-type granules were found also within narrow protrusions extending from the surface of A-type amyloplasts, but it is not certain whether they were initiated in the protrusions or passed into them from the stroma. From 25–35 days after anthesis, the A-type amyloplasts contained one A-type starch granule and numerous B-type granules, which were often attached to the parent amyloplast by a narrow constriction.

The ultrastructure of germinating barley seeds. II. Breakdown of starch granules and cell walls of the endosperm in three barley varieties

The breakdown during malting of starch granules and cell walls of the endosperm, as well as the morphological changes occurring in the scutellum and the aleurone layer, have been examined by thin sectioning and freeze-fracturing in the barley varieties Nordal, Minerva and Klages. Intact starchy endosperm cells contain large and small starch granules embedded in a matrix. In most cases the fracture plane exposes the smooth surface of the starch granules and occasionally adhering material, which probably consists of remnants of the amyloplast envelope. Degradation of the endosperm tissue during malting starts at the embryo end, and the transitional zone between intact and degraded endosperm is approximately one cell layer wide. The degradation of the large starch granules affects at the beginning only their outer edge. Subsequently, corroding channels form towards the center of the granules and elicit a rapid breakdown of the central part. Further degradation proceeds from the center giving rise to hollow shells, which finally break up into pieces. It is concluded that the susceptibility to enzyme attack increases towards the center of the large starch granules of the barley endosperm. The saw-toothed pattern observed in the corroding channels indicates, in agreement with earlier studies, that the enzyme susceptibility varies periodically in a radial direction. The three barley varieties examined differed in malting quality, but the differences were not reflected qualitatively in the ultrastructure of the scutellum, aleurone layer or the endosperm during malting.

Effects of Water Deficit on Endosperm Starch Granules and on Grain Physiology of Wheat and Barley.

Wheat (cv. Sun 9E) and barley (cv. Clipper) plants were subjected to water deficit after anthesis. In both species grain dry matter accumulation was initially unaffected by water deficit but terminated earlier in stressed plants than in controls. Water deficit did not affect endosperm cell number. In water stressed wheat plants the number of B-type starch granules per endosperm and the size of the largest A-type granules were significantly less than in control plants but A-type granule number was unaffected. Water potentials of wheat flag leaves and bracts were reduced by water deficit but this treatment did not affect grain water potential or osmotic potential during the first 29 days after anthesis. During these 29 days, neither grain nor bract water potential of barley was affected by stress and the water potential of bracts was relatively low even in control plants. Maturing grains eventually lost water and endosperm volume declined. This water loss occurred earlier in stressed plants. Stress significantly reduced the amount of sucrose per wheat grain but not the amount of sucrose per unit of grain dry matter or water content. In barley grains, stress did not reduce the relative or absolute sucrose contents. It was considered unlikely that the earlier cessation of grain growth on stressed plants was caused by insufficient assimilate. Although protein as a proportion of grain dry weight was higher in stressed plants than in controls, protein and amino acid content per grain were unaffected by water deficit.

Nucleoside Diphosphate Sugar-Starch Glucosyl Transferase Activity of wx Starch Granules

Starch granule preparations from the endosperm tissue of all waxy maize (Zea mays L.) mutants tested have low and approximately equal capability to incorporate glucose from adenosine diphosphate glucose into starch. As the substrate concentration is reduced, however, the activity of waxy preparations relative to nonmutant increases until, at the lowest substrate concentration utilized (0.1 muM), the activity of the waxy preparations is nearly equal to that of the nonmutant preparation. The apparent K(m) (adenosine diphosphate glucose) for starch granule preparations from wx-C/wx-C/wx-C endosperms was 7.1 x 10(-5) M, which is compared to 3 x 10(-3) M for preparations from nonwaxy endosperms. Starch granule preparations from three other waxy mutants of independent mutational origin have levels of enzymic activity approximately equal to wx-C at a given substrate concentration giving rise to similar apparent K(m) estimates. We conclude that there is in maize endosperm starch granules a second starch granule-bound glycosyl transferase, whose presence is revealed when mutation eliminates activity of the more active glucosyl transferase catalyzing the same reaction.

Studies on Starch Granules

AbstractIn X‐ray diffractometric studies on starch granules of many kinds of plant species, we found a variety of intermediate C‐type patterns. In particular, specimens of sweet potato starch granules varied from nearly the A‐type pattern to nearly the B‐type pattern. In these studies, we also found that spheroids of short chain amylodextrin showed very sharp diffraction patterns and that we could form amylodextrin spheroids with various types of X‐ray diffraction patterns by varying the conditions of recrystallization. Then we showed that the X‐ray patterns and physical properties of many kinds of cereal and root starches varied to some extent depending on the environmental conditions prevailing during the growth period.We examined the formation and the growth of starch granules in corn endosperm and the inner structures of these granules from the beginning to the end of their maturation by electron microscopic observations. We proved also, the appositive growth of starch granules using radio‐active carbon dioxide. Then we tried to form starch granules in vitro. But the spheroids obtained from solutions of starch components were entirely different from natural starch granules. From the findings in these experiments, an ultramacromolecular concept of the starch granule is proposed.

The size distribution of starch granules in endosperm of different sized kernels of the wheat cultivar maris huntsman

AbstractThe particle size distributions of starches prepared by proteolysis from different sized kernels of Maris Huntsman wheat, were determined by Coulter Counter. The number of starch granules was greater in “large plump” kernels than in “small plump” and “shrivelled” kernels grown under the same conditions. In all three kernel types more than one third of the total starch weight was contributed by granules less than 10 μm diameter (B type granules). The proportion of these small granules was significantly greater in “large plump” kernels than in the other two types.

Scanning electron microscopic observations of degradation of starch granules in germinating kernels of several maize (Zea mays L.) endosperm mutants in four inbred and one hybrid background and their normal counterparts.

The objective of this study was to make SEM observations of starch granules of several different maize endosperm mutants following the early germination period and to compare the relative patterns and digestibility by starch-degrading enzymes. Mature kernels of the ae endosperm mutant in four inbred lines and in a single cross hybrid and of five endosperm mutants in an inbred and a single cross hybrid, and their normal counterparts were used. Enzymatic erosion of the starch granules was visible in the disected endosperm of the normal maize following germination 4, 6 and 8 days after planting. The types of the enzymatic erosion were similar to those of the in vitro attack by a-amylase on normal starch granules. Namely, numerous pin holes were visible on the surfaces of the granules and the pores penetrated into the granules and the inner portion, which appeared to be terraced or step-shaped indicative of layered internal structures. Some types of enzymatic erosion suggested the possibility of enzymatic attack other than that of a-amylase. Starch granules of the germinating Oh43, C103, W64A, and Oh43XC103 ae endosperm mutant lines scarcely showed enzymatic erosion on their surfaces. These observations were similar to the in vitro amylase attack of ae starch granules. On the other hand, enzymatic erosion of starch granules of the B37 ae endosperm was similar to the germinating kernels of the normal B37. The types of enzymatic erosion of endosperm starch granules of the germinating su2 su2o2, wx, and 02 mutants were similar to those of their normalcounterparts.

Studies on White-Belly Rice Kernel : IV. Opaque rice endosperm viewed with a scanning electron microscope

These studies in series were devoted to clarify the characteristics of the white belly kernel which had an opaque part at the ventral portion of its endosperm. In this experiment, white belly kernels were cut transversely with a razor blade and scanning electronic photographs were taken. The experimental materials used were Norin-8, Kinmaze, Sekai-1, Gohyakumangoku (white core rice) and Sinthurumochi (glutinous rice) of Japonica type variety and Keikyakusen and Kouketuzu (glutinous rice) of Indica type variety. The following results were obtained. 1. The translucent parts of endosperm tissue of white belly kernels were easily pervious to light, but the opaque parts of endosperm tissue of these kernels were difficult to transmit light (fig. 3, 6). The permeability of light in the individual endosperm cell varied from opaque parts to translucent parts (fig. 4, 8). 2. The compound starch granules in translucent parts of white belly kernel endosperm were polygonal in shape and tightly packed with no air spaces among them (fig. 12), whereas those in opaque part of this endosperm were round in shape and loosely packed with many intergranular air spaces (fig. 10, 13, 15, 23). 3. The compound starch granules, which located the outerside of opaque parts, were easily broken into many single starch granules by the mechanical stress (fig. 15-16). 4. The opaque parts of white core, milky white, and opaque kernels had round in shape, loosely packed compound starch granules resembled with those of white belly kernels (fig. 19-22). 5. The glutinous rice had micropores on the inside surface of the single starch granules and hollows on the outer surface of compound granules, which were absent in non-glutinous rice starch granules (fig. 25-27). 6. The endosperm cells in 5-day old kernels had uniform round compound starch granules which were loosely filled with many air spaces (fig. 28-29). The endosperm cells in 16-day old kernels were packed by compound starch granules which were varied in shape and size (fig. 30-32). In more developing kernels, the compound starch granules were tightly packed in the endosperm cell and no air space was observed among the granules. Then, the endosperm tissue became translucence ( fig. 33). 7. The starch granules of endosperm had two types, i. e., one was the large compound starch granule which was composed of many single starch granules and another was the small compound starch granules which were composed of several single starch granules. Among the compound starch granules, the globular protein body were embedded (fig. 37). 8. From these results, because of the loose structure and the high proportion of inter-granular air spaces, the opaqueness of endosperm tissue would be caused by light scattering.

Hydrolysis of sorghum grain starch by rumen microorganisms and purified porcine alpha-amylase as observed by scanning electron microscopy.

Scanning electron microscopy was used to observe endosperm structure and starch hydrolysis of three sorghum grain types (waxy, yellow endosperm, bird resistant). Split kernels were subjected to either rumen digestion for 75 min. to 8 hr. or hydrolysis by purified porcine α-amylase for 48 hours. Starch granules in soft endosperm of yellow and bird-resistant types were smooth and spherical; those in a waxy variety were irregular in shape. Split kernels immersed in rumen fluid for as little as 75 min. showed differential hydrolysis: point-surface attack on the starch from the waxy grain, linear track hydrolysis on that from the yellow endosperm, and minor point hydrolysis on that from the bird resistant type. Photomicrographs of split kernels suspended inside ruminally fistulated steers indicated different modes of starch attack. Surface attack on the waxy starch was mainly point hydrolysis with alternate layers digested inside the starch granule. Yellow endosperm starch was digested without structural resistance

Studies on Germination of Barley Seeds (Part 4)

Changes of the endosperm of barley during germination were examined with the scanning electron microscope (SEM). (1) In the endosperm of ungerminated barley, large starch granules, surrounded by small granules, were embedded in amorphous cementing materials. (2) A mild erosion which might be due to the action of starch degradative enzymes was visible on the surface of some starch granules in the ungerminated barley endosperm. It is postulated that the reserve starch in the endosperm is subjected to degradation even in the process of ripening. (3) At the early stage of germination, the cementing materials embedding the starch granules disappeared and starch granules were free from the coat materials, which causally results in the facilitation of the enzymic attack of starch granules. (4) Large granules often show the equatorial grooves, which are the site of preferential attack by degradative enzymes. (5) Small granules disappeared after 3 or 4 days of germination. Small granules with pits on their surfaces have never been observed. Thus, the degradative pattern of small grannules might be quite different from that of large granules.

Einfluß von Schwefeldioxid auf die Lipide stärke‐haltiger Lebensmittel: Mais

Influence of Sulfur Dioxide on the Lipids of Starch Containing: Maize.The present paper shows that sulfur dioxide retards the lipolytic activity during the steeping process of maize. The results show that the hydrolysis of phospholipase A (E.C. 3.1.1.4) which removes one fatty acid from the phospholipide is followed by the phospholipase B (E.C. 3.1.1.5). It is not worthy that the phospholipase A is more affected by SO2 than phospholipase B. However, other lipides, e. g. galactosyldiglycerides and sterol‐containing lipides, showed no observable changes in amount. It is of interest that a relative smaller amount of free fatty acids was extracted with petrolether from maize than the original amount extracted with the same solvent before the storage. Whereas the extracted amount with butanol water did not change markedly. On the basis of this findings it may be concluded that free fatty acids are adsorbed on the starch granules of the maize endosperm.

MORPHOLOGY OF STARCH GRANULES IN CEREAL GRAINS AND MALTS

During malting, amylases have limited action on large starch granules of barley endosperm but rapidly degrade the small granules. In contrast, the small starch granules of wheat endosperm are resistant to enzymic attack. High levels of exogenous gibberellic acid increase the production of α-amylase and encourage the appearance of radial channels in the partially-degraded large starch granules. These endo-corroded granules are mainly found in the proximal (embryo) half of the endosperm where levels of α-amylase are much higher than at the distal end. Degradation of malt starch can therefore result from enzymic attack both outside and inside the granules. Malting of barley reduces the population of small starch granules which are slower to gelatinize than large granules at the infusion mashing temperatures of 65° C. During germination of barley multiple starch granules are rapidly synthesized in single amyloplasts in the scutellum. The endosperm of high amylose barley is devoid of small starch granules and the average size of the large granules is reduced. Steeliness in sorghum is related to the close packing of the starch-protein matrix rather than to unequal distribution of protein. The significance of these results is discussed, particularly in relation to the morphology of starch granules, the nature of their outer covering, the distribution of amylopectin and amylose within the granule, and the site of enzymic attack.

Studies on the origin of amylose and amylopectin in starch granules. III. The effect of temperature on enzyme activities and amylose content

Starch composition (amylose content) and the activities of starch-synthesizing enzymes were determined in cultures of Polytoma uvella and potatoes kept at various temperatures. In general ADPG-α-glucan glucosyltransferases were much less thermostable in vivo than P- and Q-enzymes. Potato phosphorylase proved to be the most stable enzyme. In Polytoma both P/Q ratio and amylose content decreased at 30 °C, whereas they remained unchanged in potatoes grown at 30 °C. This confirms the results from earlier experiments which indicated that the P/Q ratio is correlated with amylose content, and is also in agreement with the simultaneous increase in amylose percentage and P/Q ratio observed during the development of starch granules in corn endosperm. The results are discussed in relation to the problem of amylose production in starch granules and the importance of phosphorylase in starch synthesis.

DORMANCY STUDIES IN SEED OF AVENA FATUA: 3. A RELATIONSHIP BETWEEN MALTASE, AMYLASES, AND GIBBERELLIN

Initiation of germination in excised embryos requires an exogenous energy source. Normally this is obtained from the endosperm. In dormant seeds the hydrolysis of starch is blocked despite the fact that dormant and non-dormant seeds contain similar amounts of α- and β-amylases. Alone or in combination the amylases are unable to break down raw endosperm starch granules to simple sugars in vitro. Exogenous maltase in combination with α-amylase hydrolyzes raw starch to glucose. Exogenous maltase eliminates the requirement for exogenous sugar. Examination of the maltase content of imbibed dormant and non-dormant seeds showed a marked increase in non-dormant seeds during the first 40 hours. This does not occur in dormant seeds unless they are treated with gibberellic acid. The results lead to the conclusion that an important effect of gibberellic acid is to induce the synthesis of maltase or in some way activate the preformed enzyme.

Physiology of Cereal Grain II. Starch Granule Formation in the Developing Barley Kernel

Types, numbers, volumes, and weights of starch granules in the barley endosperm were measured at different times from anthesis to maturity. The formation of two types of granule was confirmed: the first (type A) was initiated until 15 days after anthesis; the second (type B) between 18 and 30 days. At maturity there were approximately 10 times as many type B granules as type A, although the latter made up 90 per cent. of the total granule volume. There was a linear relationship between starch granule and endosperm volume throughout kernel development, while the rate of increase in volume per unit granule volume was the same, irrespective of granule size, at anyone time. Starch weight increased as endosperm dry weight increased although the precise form of this relationship is in doubt. The interrelationships between starch granule weight and volume, and also endosperm dry weight and volume, suggest that both starch granules and endosperm increase in density during development.