Growth of Immature Pea Cotyledons in Culture

Millerd, Adele; Spencer, David F.; Dudman, WF; Stiller, Michael

doi:10.1071/pp9750051

Cited by 67 publications

(33 citation statements)

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“…Several observations (3,8,10,15,24) indicate that arginine, accumulating in large amounts in developing cotyledons, is synthesized in situ. Gln, the preferred N donor for CAP in vitro, is available as N donor in situ, inasmuch as the endospermic fluid, the fruit phloem sap, and cotyledons at an early developmental stage contain relatively high amounts of Gln (3,10,24).…”

Section: Discussionmentioning

confidence: 99%

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Carbamoyl Phosphate Synthetase Activity from the Cotyledons of Developing and Germinating Pea Seeds

Kollöffel

Verkerk²

1982

Plant Physiol.

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Carbamoyl phosphate synthetase activity was measured in partially purified extracts from cotyledons of developing and germinating seeds of Piswm sativum L. Some properties of the enzyme were established. During cotyledon development, the activity initially increased sharply but de-creased during further development. The activity from germinating seeds was only one-tenth of the maximum activity at an early developmental phase. The results are discussed in relation to pea seed development and germination.Carbamoyl phosphate is utilized in the first step of two biosynthetic pathways, one leading to arginine and the other to pyrimidines. In many bacteria, a single enzyme catalyzes the synthesis of CAP' for both pathways, whereas, in most animals and fungi, there are two CPSs (13, 25), each being pathway-specific. In higher plant tissues, there appears to be only one CPS supplying CAP to both pathways (22, 23).The plant enzyme, as well as the enzyme from other sources, is a regulatory enzyme influenced by a variety of effectors, such that its activity in vivo can be strictly controlled (6, 20-23 Utrecht, The Netherlands they were allowed to germinate further in darkness at 23°C for the appropriate time. The period between the beginning ofsoaking and the moment the cotyledons were used for the experiments is referred to as 'days of germination.' Developing seeds and the seeds which were allowed to germinate were, thus, harvested from the same batches of plants.Crude Extract. All isolation and purification operations were performed at 0 to 4°C. The cotyledons (40 to 60 cotyledons, corresponding with a fresh weight of 2 to 8 g, depending on the developmental phase of the seeds) were ground with a pestle in a prechilled mortar with 5 to 8 g of sand and about 10 ml of a medium containing 400 mm mannitol, 50 mm N-morpholinopropanesulfonic acid buffer (pH 7.4), and 2.5 mg/ml BSA. The homogenate was squeezed through a Perlon screen (mesh width, 45 um), diluted to about 20 ml with grinding medium, and centrifuged at 2,500g for 5 min. The supernatant was recentrifuged at 40,000g for 10 min. The resulting pellet was washed twice and suspended in the grinding medium. This suspension was used to determine the particle-bound CPS activity. The 40,000g supernatant was used as the main source of CPS.Purification of CPS. Solid (NH4)2SO4 was added to the 40,000g supernatant to 25% saturation (at 0°C). The precipitate was removed by centrifugation (10 min at 40,000g), and additional (NH4)2SO4 was added to make a final concentration of 80%o (at 0°C). Following precipitation and centrifugation, the pellet was dissolved in 3 to 3.5 ml medium containing 50 mM Tricine-KOH buffer (pH 8.0) and 10 mm Om. An aliquot (2.5 ml) was applied to a 2.6-x 25-cm column of Sephadex G-25 equilibrated with 50 mM Tricine-KOH buffer (pH 8.0), to which was added 5 mM Orn. Fractions were collected, and their relative protein content was measured by A at 280 nm. A number of fractions were pooled; aliquots were taken and subsequently used in the enzyme as...

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Section: Discussionmentioning

confidence: 99%

“…The assay mixture, in a total volume of 1.20 ml and a final pH of 8.1, contained 50 ,umol L-Gln, 10 ,umol ATP, 7.5 ,tmol Na214CO3 (0.1 Ci/mol), 15 ,Imol MgCl2, 5 ,umol of L-Orn, and 60 ,umol of Tricine-KOH buffer. The reaction was initiated by the addition of 0.5 ml extract and allowed to proceed for 15 min at 30°C.…”

mentioning

confidence: 99%

Carbamoyl Phosphate Synthetase Activity from the Cotyledons of Developing and Germinating Pea Seeds

Kollöffel

Verkerk²

1982

Plant Physiol.

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“…Cotyledons were cultured as described by Weber et al (1995) in a medium, according to Millerd et al (1975), containing 70 mM L-glutamine, 0.1 mg/L benzyladenine, and 0.02 mg/L naphthaleneacetic acid. Sugars were supplemented as indicated.…”

Section: In Vitro Culture Of Cotyledonsmentioning

confidence: 99%

A role for sugar transporters during seed development: molecular characterization of a hexose and a sucrose carrier in fava bean seeds.

et al. 1997

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To analyze sugar transport processes during seed development of fava bean, we cloned cDNAs encoding one sucrose and one hexose transporter, designated VfSUTl and VfSTPl, respectively. Sugar uptake activity was confirmed after heterologous expression in yeast. Gene expression was studied in relation to seed development. Transcripts were detected in both vegetative and seed tissues. In the embryo, VfSUTl and VfSTP 7 mRNAs were detected only in epidermal cells, but in a different temporal and spatial pattern. VfSTPl mRNA accumulates during the midcotyledon stage in epidermal cells covering the mitotically active parenchyma, whereas the VfSUTl transcript was specific to outer epidermal cells showing transfer cell morphology and covering the storage parenchyma. Transfer cells developed at the contact area of the cotyledonary epidermis and the seed coat, starting first at the early cotyledon stage and subsequently spreading to the abaxial region at the late cotyledon stage. Feeding high concentrations of sugars suppressed both VfSUT7 expression and transfer cell differentiation in vitro, suggesting a control by carbohydrate availability.

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“…A transfer of reserves of C or N was assumed from observation of losses by pods and gains by seeds. Pfenninger (23) that seeds of Vicia faba continued their development after removal from the plant, and several studies have reported continuing seed growth in detached pods of Pisum sativum (3,14,18,26) and Glycine max (19) cultured in aseptic conditions. In the latter, the potential role of pod tissues in supporting seed growth was not examined directly since contributing nutrition from the culture medium was involved to an unknown extent.…”

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Seed Development in Phaseolus vulgaris L. cv Seminole

Fountain¹,

Outred²,

Holdsworth³

et al. 1989

Plant Physiol.

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Phaseolus vulgaris L. cv Seminole pods removed from the plant continued their development when incubated in suitable conditions. Seeds continued to grow and develop and pods and seeds passed through an apparently normal developmental sequence to dryness. Seed growth was at the expense of pod dry weight (DW) reserves. Losses of pod DW paralleled DW gains by seeds in detached pods and in pod cylinders containing a seed. The transfer activity was apparent only within the period 10 to 30 days after anthesis (DAA) with maximal activity between 15 to 20 DAA. This period corresponds to maximum pod growth and the attainment of maximal DW. Seeds are in only the early phase of seed growth at this time. No DW transfer was observed at developmental stages beyond 30 to 35 DAA when normal senescence DW losses in pods became evident and seeds were in the later phase of seed fill. Pods or pod cylinders remained green and succulent over the transfer period, later passing through yellowing and drying phases characteristic of normal development. DW transfer was dependent on funicle integrity and was readily detectable in pod cylinders after 7 days incubation. The DW transfer activity may contribute to continuing nutrition of seeds under conditions where the normal assimilate supply to seeds becomes limiting. Defoliation and water stress treatments applied to Phaseolus plants reduced seed yields but allowed persistence of seed maturation processes such that all seeds developing to dryness were capable of germination.Early this century it was suggested that reserves deposited in legume pods might be a source of nutrition for their enclosed developing seeds (7, 23, 30; reviewed in 17). A transfer of reserves of C or N was assumed from observation of losses by pods and gains by seeds. Pfenninger (23) that seeds of Vicia faba continued their development after removal from the plant, and several studies have reported continuing seed growth in detached pods of Pisum sativum (3,14,18,26) and Glycine max (19) cultured in aseptic conditions. In the latter, the potential role of pod tissues in supporting seed growth was not examined directly since contributing nutrition from the culture medium was involved to an unknown extent. Although soybean seeds do continue their maturation in detached pods, their growth is reported to cease upon pod removal (1).More recent studies (27) of the sources of nutrition for developing legume seeds show the greater proportion comes from translocated assimilates of vegetative origin and that fruit reserves provide only a limited supply. Temporary storage of incoming assimilates which may involve conversion to more useful forms has been suggested to account for the remarkable linearity of seed growth in the short term independent of diurnal or day to day fluctuations in supply in soybean (28). This argument is likely to find general application at least in species with relatively fleshy pods (6, 28) and complements other recognized functions ofpods in protecting the developing seeds, and acting as photo...

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Growth of Immature Pea Cotyledons in Culture

Cited by 67 publications

References 0 publications

Carbamoyl Phosphate Synthetase Activity from the Cotyledons of Developing and Germinating Pea Seeds

Carbamoyl Phosphate Synthetase Activity from the Cotyledons of Developing and Germinating Pea Seeds

A role for sugar transporters during seed development: molecular characterization of a hexose and a sucrose carrier in fava bean seeds.

Seed Development in Phaseolus vulgaris L. cv Seminole

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