Wheat Caryopses Research Articles

Uptake of Triticonazole, during Imbibition, by Wheat Caryopses after Seed Treatment

Uptake of Triticonazole, during Imbibition, by Wheat Caryopses after Seed Treatment

Cultural characteristics and zearalenone production by strains ofFusarium from wheat

Conidia of the speciesFusarium culmorum /W.G.Sm./ Sacc. andFusarium graminearum Schwabe are characterized by variability in zearalenone production and dimensions depending on the substrate. The sporulation of isolates from some wheat eultivars have been deprived in vivo and in vitro in the first passage, but not their pathogenicity and toxic metabolites production. Nonsporulating strains produced lower quantités of zearalenone than sporulating ones. Liquid filtrates of such nonsporulating strains had a high phytotoxic effect on wheat caryopses. The crystalline toxin DAS /0,25 ug/ml/ had low phytotoxic effect on wheat caryopses.

Some effects of non-endosperm components of wheat and of added gluten on wholemeal bread microstructure

The crumb microstructure of wholemeal bread was studied using Scanning electron microscopy. This technique revealed that the wholemeal crumb, which contrasts markedly with that of white bread, is coarse, and consists of thick gas-cell walls and a discontinuous gluten-protein matrix. It is characterized by the presence of nonendosperm components from the wheat caryopsis, including bran, epicarp hairs and particles rich in aleurone-pericarp. The non-endosperm components, notably the epicarp hairs, appear to play a prominent role in disrupting the gluten-protein matrix. Removing epicarp hairs by pearling improved Significantly (P < 0·001) the baking performance of the resultant flour. Pearlings, in which most of the epicarp hairs were present, detrimentally affected the baking performance when added back to flour milled from pearled wheat. The gas-cell walls of gluten-supplemented wholemeal bread appear to be thicker, Smoother and more continuous than those from the unfortified flour. The gluten supplement may 'strengthen' the gas-cell walls, thereby counteracting the adverse effects of the non-endosperm components.

Activity of UDP-Glucose Glucosyl Transferase and its Role in the Carbohydrate Metabolism of Wheat Caryopsis

The experiments were focussed on the question whether starch synthase II (UPD glucose α-glucan 4 α-glucosyl transferase, E.C. 2.4.1.11) functions as glucosyl donor for starch synthesis in wheat grains. The results obtained confirmed that the glucans formed by the enzymes were not hydrolyzed by β-amylase whereas additions of cellulase resulted in hydrolysis. According to this finding it is assumed that the UDP-glucose glucosyl transferase plays no role in starch synthesis but is rather involved in the formation of β-glucans which probably are related to the formation of cell wall material.

Uptake of triadimenol through wheat caryopsis after application by seed treatment

AbstractThe uptake of triadimenol was investigated by offering radio‐labelled chemical exclusively through the caryopsis in a special experimental design with single seed grains in plexiglass holders. In totally‐treated caryopses about 5% and, in partially‐treated caryopses (embryo untreated), 4.5% of the applied radioactivity reached the winter wheat shoots after 21 days up to the third leaf stage. Uptake of active ingredient through the pathway pericarp‐testa‐endosperm‐scutellum‐seedling up to the third leaf stage D(13) was therefore confirmed. Furthermore, [14C] triadimenol was also translocated through the caryopses into the roots and was released to the nutrient solution.

Tilletia indica: cytology and teliospore formation in vitro and in immature kernels

In teliospores of Tilletia indica Mitra meiosis occurred at germination, followed by a series of mitoses in teliospores, promycelia, or both, resulting in promycelia with numerous haploid nuclei. Primary sporidia initially were single, monokaryotic cells. After abstriction cell division occurred, but each cell stayed monokaryotic. Mycelia isolated from incipiently infected wheat caryopses formed teliospores on potato sucrose agar after 2–3 weeks and continued to do so for about 2 years. Nuclear stages of the fungus in culture and host tissue were demonstrated with haematoxylin, HCl–Giemsa, and (or) the Feulgen nucleal reaction. During formation of teliospores in vitro, conjugately associated nuclei of sporogenous mycelia migrated to probasidial initials which formed at right angles to the parent hypha. The dikaryotic probasidia usually were subtended by Y-shaped septa. Karyogamy was not seen, but circumstantial evidence suggested that it occurred during very early stages of probasidial development because even immature teliospores were monokaryotic. The process of teliospore formation and the concomitant changes in nuclear condition were easily observed in cultures, but in vivo the gelatinoid nature of the mycelium in the host tissue made this much more difficult. Moreover, some stages of teliospore formation observed in vitro were not seen in soral sections and presumably did not form in son on the host.

Induction of Sensitivity to Gibberellic Acid in Developing Wheat Caryopses: Effect of Sugars in the Culture Medium

The influence of sugars in culture media on the development of the ability of the aleurone layer to respond to gibberellic acid was investigated by culturing detached wheat ears for 6 days and then measuring the hormone-induced α-amylase activity in incubates of endosperm halves derived from the cultured ears. Some response to gibberellic acid was found after ears had been cultured on water, or on solutions of either sorbitol or mannitol. Addition of mineral nutrients plus glutamine to these culture media reduced the response. Likewise, the addition of sucrose, glucose and/or fructose or galactose reduced the response, and a complete culture medium abolished the response, giving endosperm halves which were similar to those from ears retained on the plant. Supplying mannose to the culture medium yielded endosperm halves as responsive to gibberellic acid as those from fully air-dried caryopses. The separate effects of mannose and sucrose were concentration dependent in the range 1-10 mM. Adding mannose and/or glucose to GA3-containing incubates of endosperm halves did not alter the intensity of α-amylase activity in these incubates. The results were interpreted as an effect of the sugars on the metabolic status of the inflorescence.

Homology among 3S and 7S Globulins from Cereals and Pea

The globulins from wheat caryopses were found to consist primarily of protein sedimenting at approximately 3S and 7S. These proteins displayed a molecular weight distribution similar to that of the purified vicilin-like fractions from oat and pea, with variations occurring in the isoelectric points and relative quantities of their major subunits. concanavalin A Sepharose chromatography suggested that the major polypeptides of the wheat (3S + 7S) fraction are glycosylated. Western blot analysis using antioat (3S + 7S) globulin immunoglobulin G revealed the vicilins from pea and the globulin fractions of oat, wheat, barley, rye, corn, and rice to contain immunologically homologous polypeptides. Major groups of polypeptides were shared by all the cereals and pea, including subunits of approximately 75, 50, 40 kilodaltons and 20 to 25 kilodaltons. These results indicate that legume-like 3S and 7S globulins have been conserved and are being expressed in cereals.

Distribution of cadmium, copper, and zinc in the caryopsis of wheat (Triticum aestivum L.)

Cadmium, copper, and zinc were quantitatively determined in the whole grain, the germ, the aleurone layer, the outer pericarp, and the endosperm from the caryopsis of wheat (Triticum aestivum L.) by the methods of direct solid microsampling and flame-AAS, respectively. Metal concentrations markedly differed among the tissues investigated. Both methods used in this study produced almost identical heavy metal concentrations. However, the techniques dramatically differed in the amounts of grain material required for analysis.

MORPHOLOGICAL STAGING OF WHEAT CARYOPSIS DEVELOPMENT

Growth and size measurements as well as morphological characteristics of wheat (Triticum aestivum L. cv. Chinese Spring) caryopsis development are classified into five (I–V) groups, each representing a distinct developmental stage. Such staging will hopefully aid in experimental approaches and comparative studies of wheat embryo and endosperm development.

Discoveries of cultivated plants in the early farming settlements of Yarym-Tepe I and Yarym-Tepe II in Northern Iraq

In the settlement site of Yarym-Tepe in northern Iraq, the expedition of the USSR Academy of Sciences has extracted carbonized grains from layers dated to the 6th and 5th millennia BC. The main component of the samples from the 6th millennium BC is hulled many-rowed barley ( Hordeum vulgare L.). In the 6th millennium samples, Hordeum distichon L. (two-rowed barley), H. lagunculiforme Backt. (bottle-shaped barley) and H. vulgare L. nuclum (naked barley) of the type with small rounded caryopses were found as admixtures. Single caryopses of wheat were also discovered: hulled Triticum dicoccum Schrank and T. spelta L., and naked wheat of T. durum Desf. and T. aestivum L. type. Distinctly monospecific populations of Hordeum vulgare L., Hordeum vulgare nudum (of the type with large, oval caryopses), Triticum dicoccum Schrank and T. spelta L. are represented in samples from the 5th millennium BC. Among the hulled many-rowed barley grains a fairly large number of specimens with remains of a fruit-stalk were found. This demonstrates the occurrence in the barley populations from Yarym-Tepe of Hordeum lagunculiforme Backt., an archaic form of barley which is related to Hordeum spontaneum C. Koch emend. Backt. The latter species is still growing in natural communities in northern Iraq. The simultaneous existence, in the early stages of the development of agriculture, of two-rowed and six-rowed forms of barley, which have both arisen from Hordeum spontaneum C. Koch emend. Backt., confirms N. I. Vavilov's conception of the Linnean species as a system of multiform hereditary variation. The total evidence from the cultivated plant species discovered at Yarym-Tepe provides support for a local origin of agriculture. It developed under dry-farming conditions in an intermontane valley where the evolution of plants proceeded more actively. Artificial selection yielded new forms and, as a result, comparatively pure monospecific crops existed already in the 5th millennium BC.

Development of Responsiveness to Gibberellic Acid in the Aleurone Layer of Immature Wheat and Barley Caryopses: Effect of Temperature

Immature wheat caryopses were dried at different temperatures ranging from 4 to 30°C and the kinetics of increase of α-amylase activities in endosperm halves treated with gibberellic acid were investigated. Over the duration of the experiments the kinetic curve comprised of lag, curvilinear and linear phases, and the curvilinear phase could be fitted by a quadratic expression. The square root of α-amylase activity due to gibberellic acid was linearly related to time and from this the acceleration rate of production of α-amylase and duration of lag phase could be calculated. The calculated acceleration rate for the production of α-amylase was correlated with drying temperatures below 20°C but not above. The lag phase for dry endosperm halves was biphasic, consisting of a gibberellic acid insensitive phase (hydration phase) and a hormone sensitive phase, the only phase present in fully imbibed endosperm halves. Duration of the hydration phase was inversely correlated with drying temperatures below 15°C but not above, whereas the duration of the subsequent hormone sensitive phase was not correlated with drying temperature. It was concluded that low drying temperatures modified the subsequent behaviour of the aleurone layer, delaying the onset and reducing the rate of gibberellic acid-induced processes, which culminate in the production of °-amylase.

Induction of Sensitivity to Gibberellic Acid in Developing Wheat Caryopses: Effect of Rate of Desiccation

No change in the total β-amylase activity, attributable to the presence of 10-6 M gibberellic acid (GA3) in the incubation medium, was found in freshly harvested, de-embryonated, immature (11-38 days post-anthesis) caryopses of wheat. Significant amounts of GA3-induced α-amylase activity was found in 26-h incubates of similar caryopses which had been allowed to dry out either in the ear or detached from the ear. After 10 days of storage of detached immature caryopses in air of 99-100% relative humidity, de-embryonated half-caryopses responded to applied GA3 by producing α-amylase. More α-amylase was found in 26-h incubates if detached caryopses dried out slowly, but rapid desiccation led to little or no α-amylase being produced in the presence of GA3. Caryopses taken from ears cultured on 0.4 or 4% sucrose for 10 days did not respond to applied GA3 whereas those from ears cultured on water did respond, although the amount produced in 26-h incubates was not as large as those from slowly dried ears. Development of the ability to respond to GA3 by increasing α-amylase activity depended on the duration of desiccation or isolation from the plant. Changes in metabolism emanating from the interruption to the supply of sucrose to the caryopsis may be involved in the development of the ability of the aleurone to respond to GA3.

Pre-harvest mould and yeast floras on the flag leaf, bracts and caryopsis of wheat

Using a dilution-plating technique, the microflora of the wheat flag leaf, bracts (lemma and palea) and caryopsis was examined from ear emergence to harvest. Aureobasidium pullulons (de Bary) Arnaud and Cladosporium spp. (C. cladosporioides (Fres.) de Vries and C. herbarum (Pers.) Lk ex Fr.) were the earliest established filamentous fungi on all organs; Alternaria alternata (Fr.) Keissl. and Verticillium lecanii (Zimm.) Viègas followed and Epicoccum purpurascens Ehrenb. ex Schlecht. appeared later on the dying leaf and bracts and on the ripening caryopsis. The predominant yeasts throughout the survey were Cryptococcus spp.* (Cr. laurentii (Kuff.) Skinner and Cr. albidus (Saito) Skinner, Sporobolomyces roseus Kl. & van Niel and Torulopsis ingeniosa di Menna, accompanied by the red yeasts Cr. macerons (Frederiksen) Phaff & Fell and Rhodotorula glutinis (Fres.) Harrison in the early stages of development, and Trichosporon cutaneum (De Beurm., Gougerot & Vaucher) Ota during ripening.

Synthese von DNA im Gammapflänzchen von Weizen / DNA-synthesis in Gamma-plantlets of Wheat

Plants, arising from irradiated (300 kR) caryopses of wheat, exhibit a low incorporation of [3H]thymidine into the DNA, which, as shown by sedimentation on sucrose gradients, does not indicate tendencies of normalization.

Scanning Microscope Observations of the Pigment Strand in the Caryopsis of Wheat

Structural features of the tissues of the pigment strand in the caryopsis of wheat were studied by means of the scanning electron microscope.

On the location of glutamate decarboxylase in the caryopsis of hard wheat (Triticum durum) and its activity during early germination.

La glutammico decarbossilasi e localizzata nell'embrione di semi secchi diTriticum durum, mentre l'endosperma ne risulta praticamente privo. Durante la germinazione si ha un aumento dell'attivita specifica GAD alla sesta ora di imbibizione, seguita da una lenta e progressiva diminuzione per le seguenti 24 ore. L'enzima e attivato dal piridossal-5′-fosfato, ma le variazioni di attivita GAD durante la germinazione non sembrano dipendere direttamente dalla concentrazione del coenzima.

Radiobiological investigations in cereals. VI. EPR measurements in single caryopses of wheat

Characteristic properties of free radicals in the different parts of caryopses of wheat were determined at room temperature with electron paramagnetic resonance (EPR) techniques, using single caryopses or samples of 10–20 isolated embryos. The seed coatings and the embryo each contain a characteristic narrow endogenous radical signal. After gamma-irradiation of the caryopses, the peak-to-peak width of these narrow signals remains constant but a new, broad signal is induced in the endosperm at higher doses which obscures the narrow signals. At low doses the induced radical content per unit weight is about 50 per cent higher in the embryo than in the endosperm or in the seed coatings. A possible relationship between radiation induced radicals and radiation damage is discussed suggesting radical migration as a working hypothesis.

Studies on the Ontogeny of the Pigment Strand in the Caryopsis of Wheat

The grain of wheat has a groove that extends inward nearly to the centre of the grain. At the base of this crease and extending through its length there is a strand of coloured tissue, the pigment strand. At about 3 days after anthesis the cells of this strand of tissue are similar to meristematic cells, possessing thin walls and the usual complement of organelles. At about 9 days after anthesis the cell walls thicken and lignify.

An immunochemical approach to species relationship in Triticum and some related species

An immunological reaction, precipitation in gel, was produced using a rabbit antiserum directed to a specific protein constantly present in bread wheats (T. aestivum, genome AABBDD), but absent in durum wheat (T. durum Desf., genome AABB). This protein was isolated in the soluble-protein fraction of bread wheat caryopses by combined biochemical and immunological techniques.The availability of such a specific anti-bread wheat serum made possible the analysis of a series of varieties and species of wheat and of some closely related (Secale, Aegilops) and less closely related (Hordeum, Haynaldia) taxa to determine whether the protein was present or absent. Hordeum vulgare, Haynaldia villosa, Triticum monoccocum and Triticum turgidum gave a negative result, while positive results were obtained in T. aestivum, T. timopheevi, T. zhukovskyi, Secale cereale, Aegilops speltoides, Ae. mutica, Ae. comosa, Ae. caudata, Ae. umbellulata, Ae. squarrosa, and also in the artificial amphiploids (Ae. speltoides x T. monococcum) and (Ae. caudata x T. monococcum).It is concluded that these results agree closely with the classification of Triticum proposed by MacKey in 1966. The investigated protein not only permits the differentiation of T. aestivum from T. turgidum, but also T. turgidum from T. timopheevi at tetraploid level and T. monococcum from all the diploid species of Aegilops.