The role of gibberellin and the hulls in the control of germination in Aegilops Kotschyi caryopses

1974 ◽  
Vol 52 (7) ◽  
pp. 1597-1601 ◽  
Author(s):  
Judith Wurzburger ◽  
Y. Leshem ◽  
D. Koller
Keyword(s):  
Gibberellic Acid ◽  
Seed Coat ◽  
Filter Paper ◽  
Amylase Activity ◽  
Pronounced Effect

Large and small Aegilops Kotschyi caryopses have low α-amylase activity. After imbibition in water a marked increase takes place in α-amylase activity in the large, hulled and dehulled caryopses and only a slight increase in the small ones. Exogenously applied gibberellic acid (GA3) enhances α-amylase activity in both caryopses, and also improves germination of the small, hulled caryopses.Removing parts of the hull from different sites on the palea or lemma of the small caryopses improves germination. The most pronounced effect was obtained when the segment was removed from the palea just above the embryo. When this excised site was covered with a strip of wet filter paper before germination, the resulting germination was essentially similar to that of the non-excised controls.The role of GA3 and seed coat in improving germination of small Aegilops caryopses is discussed.

Induction of Sensitivity to Gibberellic Acid in Wheat and Barley Caryopses: Effects of Dehydration, Temperature and the Role of the Embryo during Caryopsis Maturation

1986 ◽  
Vol 13 (6) ◽  
pp. 785 ◽  
Author(s):  
PB Nicholls
Keyword(s):  
Gibberellic Acid ◽  
Filter Paper ◽  
Amylase Activity ◽  
Glycerol Water ◽  
Acid Sensitivity ◽  
Aqueous Buffer ◽  
Buffer Solutions ◽  
Lag Period ◽  
Rate Of Accumulation

The development of gibberellic acid sensitivity, which is measured by the level of α-amylase activity, has been investigated by comparing enzyme levels in freshly detached wheat and barley caryopses cultured on moist filter paper for various times and temperatures with those in caryopses dried over 35% (w / w) glycerol-water solutions or in caryopses air-dried in detached ears at controlled temperatures and by comparing enzyme levels in de-embryonated caryopses with intact ones, both being cultured in aqueous buffer solutions. Similar amounts of enzyme were produced in caryopses held moist or dried, although the duration of the lag period, and the rate of accumulation of α-amylase were markedly influenced by the length and temperature of main treatments. Likewise similar amounts of enzyme were produced in de-embryonated and intact caryopses cultured in an aqueous buffer if the latter were de- embryonated prior to incubation in solutions of gibberellic acid. However, when intact or de-brushed (removal of the apical tip) caryopses were incubated with GA3, less α-amylase was found in these incubates than in those incubates containing de-embryonated caryopses. These observations were found in incubates of both sensitized freshly harvested and normal mature caryopses. It is concluded that drying is not essential for the development of gibberellic acid sensitivity in the wheat and barley caryopses.

scholarly journals Role of the Seed Coat in Dormancy of Eucalyptuspauoiflora and E. Delegatensis Seeds

1967 ◽  
Vol 20 (6) ◽  
pp. 1237 ◽  
Author(s):  
EP Bachelard
Keyword(s):  
Gibberellic Acid ◽  
Seed Coat ◽  
Gaseous Exchange ◽  
Eucalypt Species ◽  
Phacelia Tanacetifolia

Gibberellic acid promotes the germination of dormant seeds of some eucalypt species including Eucalyptus pauciflora Sieb. and E. delegatensis R. T. Baker. It was suggested that gibberellic acid may stimulate germination by promoting enzymatic weakening of the seed coat (Bachelard 1967) as described for Phacelia tanacetifolia seeds (Chen and Thimann 1964). Previously, Grose (1963) suggested dormancy of of E. delegatensis seeds might be due to the seed coat limiting gaseous exchange.

scholarly journals POPULATION GENETICS OF DROSOPHILA AMYLASE. IV. SELECTION IN LABORATORY POPULATIONS MAINTAINED ON DIFFERENT CARBOHYDRATES

Genetics ◽  
1983 ◽  
Vol 103 (4) ◽  
pp. 675-689
Author(s):  
Jeffrey R Powell ◽  
Marko Andjelković
Keyword(s):  
Structural Gene ◽  
Amylase Activity ◽  
Enzyme System ◽  
Specific Expression ◽  
Carbohydrate Source ◽  
Laboratory Populations ◽  
Consistent Change ◽  
Regulation Changes ◽  
Starch Medium

ABSTRACT Two polymorphic systems impinging on α-amylase in Drosophila pseudoobscura have been studied in laboratory populations maintained on medium in which the only carbohydrate source was starch (the substrate of amylase) and replicas maintained on medium in which the only carbohydrate source was maltose (the product of amylase). The two polymorphic systems were alleles at the structural gene (Amy) coding for the enzyme (allozymes) and variation in the tissue-specific expression along the adult midgut controlled by several genes. In the seven populations on maltose medium little consistent change was noted in either system. In the seven populations on starch medium, both polymorphisms exhibited selective changes. A midgut pattern of very limited expression of amylase rose in frequency in all starch populations, as did the frequency of the "fast" (1.00) Amy allele. The overall specific amylase activity did not differ between starch-adapted and maltose-adapted flies.—The results, along with previous studies, indicate that when a gene-enzyme system is specifically stressed in laboratory populations, allozymes often exhibit selective differences. Such results make the selectionist hypothesis at least tenable. Furthermore, the fact that both types of polymorphisms responded to selection indicates the role of structural gene vs. gene regulation changes in adaptive evolution is not an either/or question but one of relative roles and interactions.

The role of gibberellic acid in the hydrolysis of endosperm reserves in Zea mays

Planta ◽  
1974 ◽  
Vol 121 (1) ◽  
pp. 67-74 ◽  
Author(s):  
B. M. R. Harvey ◽  
Ann Oaks
Keyword(s):  
Zea Mays ◽  
Gibberellic Acid ◽  
Hydrolysis Of

(Washington University case conference): acute pancreatitis, hyperlipemia, and normal amylase.

1978 ◽  
Vol 24 (5) ◽  
pp. 815-820 ◽  
Keyword(s):  
Acute Pancreatitis ◽  
Serum Amylase ◽  
Amylase Activity ◽  
Normal Serum ◽  
Case Conference ◽  
Diagnosis And Management ◽  
Serum Amylase Activity ◽  
Washington University

Abstract This case focuses on the biochemical findings in acute pancreatitis and the role of the laboratory in the diagnosis and management of such patients. It also illustrates a major unappreciated problem in the use of amylase determinations in patients with acute pancreatitis: normal serum amylase activity in the presence of hyperlipemia.

The role of fractures and lipids in the seed coat in the loss of hardseededness of six Mediterranean legume species

2005 ◽  
Vol 143 (1) ◽  
pp. 43-55 ◽  
Author(s):  
L. W. ZENG ◽  
P. S. COCKS ◽  
S. G. KAILIS ◽  
J. KUO
Keyword(s):  
Seed Coat ◽  
Lipid Content ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Petroleum Jelly ◽  
Physicochemical Changes ◽  
Ornithopus Sativus ◽  
Seed Coats ◽  
Seed Coat Morphology

Changes in the seed coat morphology of 12 annual legumes were studied using environmental scanning electron microscopy (ESEM). The seeds of Biserrula pelecinus L. cv. Casbah, Ornithopus sativus cv. Cadiz, Trifolium clypeatum L., T. spumosum L., T. subterraneum L. cv. Bacchus Marsh, Trigonella balansae Boiss. & Reuter., Trigonella monspeliaca L. and Vicia sativa subsp. amphicarpa Dorthes (morthes.) were examined by ESEM after exposure to field conditions for 6 months, while those of Medicago polymorpha L. cv. Circle Valley, Trifolium clypeatum L., T. glanduliferum Boiss., T. lappaceum L., T. spumosum L., and T. subterraneum L. cv. Dalkeith, were examined after 2 years' exposure. The entry of water into seeds was followed by covering various parts of the seed coat with petroleum jelly and soaking the treated seeds in dyes.As the seeds softened over time, more and larger fractures appeared on the seed coat. Water entered the seed either through fractures, over the seed coat as a whole or through the lens. It is hypothesized that the formation of fractures occurs after physicochemical changes in the seed coat, probably associated with changes in the amount and nature of seed coat lipids.The newly matured whole seeds of M. polymorpha cv. Circle Valley, T. clypeatum, T. glanduliferum, T. lappaceum, T. spumosum, and T. subterraneum cv. Dalkeith were analysed for lipid content in 1997. The seed coats of T. subterraneum cv. Dalkeith and T. spumosum were separated from the cotyledons and examined in detail for lipid content.The lipid content of whole seeds ranged from 48 (T. lappaceum) to 167 mg/g (T. subterraneum cv. Dalkeith). Total lipid of the whole seeds of T. subterraneum cv. Dalkeith and T. glanduliferum declined by about 9 mg/g over 2 years, while in T. spumosum it declined by about 17 mg/g.In contrast, the major fatty acids in the seed coat declined by 0·67 mg/g over the 2 years. Change in seed coat lipids showed a marked similarity to changes in hardseededness for both T. subterraneum cv. Dalkeith and T. spumosum. The results strongly suggest that seed softening is associated with loss of lipids in the seed coat, because lipids have physical characteristics that are altered at temperatures experienced in the field.

Germination of Seeds From the Fruits of Thryptomene calycina (Myrtaceae)

1993 ◽  
Vol 41 (2) ◽  
pp. 263 ◽  
Author(s):  
DV Beardsell ◽  
RB Knox ◽  
EG Williams
Keyword(s):  
Gibberellic Acid ◽  
Sulphuric Acid ◽  
Seed Coat ◽  
Major Site ◽  
Low Concentrations ◽  
Viable Seeds ◽  
Insect Predation

Freshly fallen fruits of T. calycina contained seeds which were completely dormant; none germinated after 200 days at 20°C. Seeds excised with testas intact from fresh fruits were partially dormant; one-third germinated after 60 days. The dormancy of seeds in freshly fallen fruits was imposed jointly by the fruit and the seed. The major site of the dormancy was however the seed coat since tearing part of it away from seeds excised from fresh fruits resulted in rapid and complete germination. Fruits stored dry in a laboratory at 20°C for 90 days were partially dormant. Nicking the distal end of these fruits enhanced germination. Seeds excised from these laboratory stored fruits had 85 % germination, which indicated a reduction in the seed imposed dormancy. Germination of T. calycina was independent of light and, although the fruits contained large amounts of phenolic material this did not inhibit germination. Fruits weathered in the field for at least 2 years contained less viable seeds, presumably because of insect predation, but these all germinated within 50 days at 20°C. Brief washing of fruits in concentrated sulphuric acid increased germination. Germination was not enhanced by treatment with low concentrations of gibberellic acid in the presence or absence of cytokinin.

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