Conditions Affecting Enzyme Synthesis in Cotyledons of Germinating Seeds

Young, James L.; Huang, Rongmin; Vanecko, Steve; Marks, Joy D.; Varner, Joseph E.

doi:10.1104/pp.35.3.288

Cited by 50 publications

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“…9, 13, 22). A rapid increase in mitochondrial activity was also observed during the early stages of germination of pea seeds (34). In a previous paper (20), we reported a rapid development of mitochondria including increases in their components and activities in the cotyledons of pea seeds during the imbibing stages.…”

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Biochemical Studies on Development of Mitochondria in Pea Cotyledons during the Early Stage of Germination

Nawa¹,

Asahi²

1973

Plant Physiol.

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L-Leucine-U-'4C was incorporated into mitochondrial protein in pea (Pisum sativum var. Alaska) cotyledons during the imbibing stages. Incorporation was almost completely inhibited by cycloheximide but not by chloramphenicol. Both antibiotics did not affect increases in mitochondrial activities and components of the cotyledons during imbibition. Therefore, mitochondrial development seems to be achieved by a transfer of protein pre-existing in the cytoplasm into the mitochondria rather than by de novo synthesis of mitochondrial protein. Cycloheximide stimulated an increase in bile saltsoluble protein of mitochondria in imbibing pea cotyledons. The recovery of cytochrome oxidase activity after sucrose density gradient centrifugation was enhanced, and the morphological properties of mitochondria were altered by cycloheximide.When water is supplied to dry seeds, a marked increase occurs in their respiratory activity. A number of studies have demonstrated that mitochondrial development takes place in the cotyledons or endosperms during the later stages of germination (1, 3-5, 8. 9, 13, 22). A rapid increase in mitochondrial activity was also observed during the early stages of germination of pea seeds (34). In a previous paper (20), we reported a rapid development of mitochondria including increases in their components and activities in the cotyledons of pea seeds during the imbibing stages. The structure of mitochondria seems to be stabilized as hydration proceeds. Recently, similar results were reported by Solomos et al. (31).Our studies have been expanded in an attempt to elucidate the mechanism of development of pea cotyledon mitochondria during the imbibing stages. The purpose of the study described in this paper was to determine if the development involves the de novo synthesis of mitochondrial protein. The synthesis of mitochondrial protein is the result of two systems controlled by different genes; one is the cytoplasmic protein-synthesizing system controlled by nuclear genes, and the other is a mitochondrial protein-synthesizing system. The former is inhibited by CHI' and the latter by CAP (2,25,30,32,33). This paper deals 'Abbreviations: CHI: cycloheximide; CAP: D-threochloramphenicol; SDGC: sucrose density gradient centrifugation; RCR: respiratory control ratios.with the effects of the antibiotics on the development of mitochondria in pea cotyledons during the imbibing stages. Our study would suggest that development does not require a de novo synthesis of mitochondrial protein but seems to be achieved by a transfer of pre-existing cytoplasmic protein to immature mitochondria. MATERIALS AND METHODSPlant Material. Surface-sterilized pea seeds (Pisum sativum var. Alaska) were germinated in the dark at 28 C in Petri dishes containing deionized water or antibiotic solution (1 or 0.5 mM CHI, 5 or 1 mm CAP) 2.5 times that of the dry seed weight.The cotyledons were taken at the appropriate age, washed with water, and used as the experimental material. L-Leucine-U-14C was supplied to the seeds by germinati...

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confidence: 93%

Biochemical Studies on Development of Mitochondria in Pea Cotyledons during the Early Stage of Germination

Nawa¹,

Asahi²

1973

Plant Physiol.

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“…This paper describes the influence of a factor or factors from the axis tissues on the course of senescence of excised pea cotyledons. Earlier papers (4,5) was necessary to consider the possibility that a deleterious factor might be moving out of the cotyledons into the axis. The data reported here indicate that the interaction results from the transport of some factor or factors from the axis into the cotyledons during the 1st andl 2nd day of germination.…”

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Senescence of Cotyledons of Germinating Peas. Influence of Axis Tissue

Varner¹,

Balce²,

Huang³

1963

Plant Physiol.

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“…Studies of biochemical changes in seeds which have initiated germination processes (1,9,31) show a dramatic rise in activity of many enzymes within a very short time. Wasserman (29), working with light microscopy, was unable to see mitochondria in cells of the dry seed.…”

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THE ULTRASTRUCTURE OF COTYLEDONARY TISSUE FROM GOSSYPIUM HIRSUTUM L. SEEDS

Yatsu

1965

The Journal of Cell Biology

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Quiescent cottonseeds stored in a dry, anaerobic situation for over a year have been shown to contain cells whose contents are ultrastructurally similar to those of normal, fully hydrated plant cells. Plastids, mitochondria, and nuclei of the cells of cotyledon tissue in dry seeds possess normal-looking double membranes even under conditions of extreme desiccation. Previous reports have indicated on the basis of light microscopic work, that the cells of certain dry seeds do not possess nuclear membranes or mitochondria. The cells of the dry cottonseed do contain these structures, however. Dictyosomes have not been observed in the spongy parenchymal cells of the cotyledon tissue; it is suggested that they are concerned with translocation and/or utilization of material. The storage materials in the cells, protein and oil, are contained in vacuolar areas enclosed by a single membrane.Seeds offer a convenient base line in ontogenetic studies of the plant. Many ultrastructural studies have been directed to the terminal stages of seed development (7,8,12,17,27) or to the initial stages of seed germination (4,10,18,22,28), but relatively few studies have been conducted on the dry seed per se. Yet an understanding of the final changes on maturation and the first events of germination requires information on the mature, quiescent seed as a point of reference.Studies of biochemical changes in seeds which have initiated germination processes (1, 9, 31) show a dramatic rise in activity of many enzymes within a very short time. Wasserman (29), working with light microscopy, was unable to see mitochondria in cells of the dry seed. However, within 12 to 24 hours after the seeds had imbibed water, mitochondria in cells became visible, presumably arising de novo. Thus, it is obvious that changes occur quite rapidly in seeds after imbibition of water.Unfortunately, most electron microscope studies have been conducted on seeds which were allowed to imbibe water for various periods prior to fixation (16,18,25,28). Since rapid changes do occur in seeds upon imbibition of water, any technique involving imbibition of water, even for short periods, may not reflect their original condition. The paucity of studies on dry seeds is probably due to the extreme difficulty of working with them. This study, therefore, was undertaken to determine the structure of cells in dry, quiescent seeds fixed directly without prior hydration. MATERIALS AND METHODSA master sample of cottonseed (Gossypium hirsutum L., var. Acala 4-42-77, Glandless) harvested in Fall, 1962 was stored in a vacuum desiccator with a desiccant at 3°C and subsamples were removed as needed. Sections of tissue approximately 0.3 mm in diameter were cut carefully from the seed and fixed immediately in two different fixatives, osmium tetroxide and permanganate salts. OSMIUM :Since earlier work indicated that various solvents deranged the normal structure of the dry

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Conditions Affecting Enzyme Synthesis in Cotyledons of Germinating Seeds

Cited by 50 publications

References 2 publications

Biochemical Studies on Development of Mitochondria in Pea Cotyledons during the Early Stage of Germination

Biochemical Studies on Development of Mitochondria in Pea Cotyledons during the Early Stage of Germination

Senescence of Cotyledons of Germinating Peas. Influence of Axis Tissue

THE ULTRASTRUCTURE OF COTYLEDONARY TISSUE FROM GOSSYPIUM HIRSUTUM L. SEEDS

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