Variations in the Basic Pathway of Chloroplast Development

Whatley, Jean M.

doi:10.1111/j.1469-8137.1977.tb04846.x

Cited by 126 publications

(76 citation statements)

References 37 publications

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“…Again, this requirement may be facilitated by early vacuolation and reduction of cytoplasmic volume relative to the total volume of the cell. Whatley (1974Whatley ( , 1977 studied the development of plastids in the leaves of Phaseolus vulgaris and Zea mays and regarded the amoeboid form as a common intermediate in a sequence of five successive developmental stages in the transition from the proplastid state to a chloroplast (Thomson & Whatley, 1980). In roots, this transition was interpreted as a spatial sequence of differentiation of plastids along the axis of a root from its tip to more mature regions (Whatley, 1983 a;Whatley & Gunning, 1981).…”

Section: Discussionmentioning

confidence: 99%

Salinity induced structural changes in meristematic cells of barley roots

Huang

Steveninck

1990

New Phytologist

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SUMMARYStructural changes occurring in meristematic cells of barley {Hordeum vulgare L. cv. California Mariout) in response to moderate salinity treatment were studied. In the apical region of the root, salt caused an increase in vacuolation which may provide a means for accumulation of excess ions. Salt treatment also caused many plastids in the cortical cells in this region to adopt varying amoeboid shapes, often appearing to enclose part of the cytoplasm which was less dense than the surrounding cytoplasm. This suggested that plastid morphology may allow or alternatively result from adaptive changes in protein synthesis or cytoplasmic composition.

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Section: Discussionmentioning

confidence: 99%

Salinity induced structural changes in meristematic cells of barley roots

Huang

Steveninck

1990

New Phytologist

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“…Our finding that a-amylase mRNA is present abundantly in the 4,000g pellet fraction, indicates that ER bearing a-amylase mRNA may be associated with amyloplasts. As (20). We are attempting to clarify this ER-amyloplast relationship by using cell fractionation coupled with electron microscopic observations.…”

Section: Methodsmentioning

confidence: 99%

Biosynthesis of α-Amylase in Vigna mungo Cotyledon

Tomura

Koshiba²

1985

Plant Physiol.

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In vitro translation of RNA extracted from Vigna mungo cotyledons showed that a-amylase is synthesized as a polypeptide with a molecular mass of 45,000, while cotyledons contain a form of a-amylase with a molecular mass of 43,000. To find out whether the 45,000 molecular mass polypeptide is a precursor to the 43,000 found in vivo, the cell free translation systems were supplemented with canine microsomal membrane; when mRNA was translated in the wheat germ system supplemented with canine microsomes, the 45,000 molecular mass form was not processed to a smaller form but the precursor form was partly processed in the membrane-supplemented reticulocyte lysate system. When V. mungo RNA was translated in Xenopus oocyte system, only the smaller form (molecular mass 43,000) was detected. Involvement of cotranslational glycosylation in the maturating process of the a-amylase was ruled out because there was no effect of tunicamycin, and the polypeptide was resistant to endo-6-H or endo-j,-D digestion. We interpret these results to mean that the 45,000 molecular mass form is a precursor with a signal peptide or transit sequence, and that the 43,000 molecular mass is the mature form of the protein.Numerous investigations have been carried out on the mechanism of a-amylase synthesis and transport in both microorganisms and eukaryotes. In all cases, the enzyme appears to be a secretory protein. Investigations with plants (wheat, barley, and rice) showed that a-amylase is synthesized as a precursor polypeptide. In wheat, the larger precursor was processed to the mature form in Xenopus oocytes and by canine microsomes (2), but not by the RER obtained from aleurone layers (15). In barley, newly synthesized a-amylase is associated with the ER (6, 9). In rice, extensive glycosylation is preceded by proteolytic processing during the synthesis of a-amylase (12). Recently, cDNA complementary to mRNA sequence of wheat and barley a-amylase was obtained, and nucleotide sequencing showed that the enzymes have typical signal sequences at their N-terminal ends (16,17 brane. We found that in the cotyledons, a-amylase is synthesized as a large precursor by membrane-bound polysomes, cleaved to mature form in cell-free translation systems supplemented with canine pancreas microsome, and in Xenopus oocyte system. In addition, mature a-amylase is not glycosylated. Possible mechanisms of intracellular transport of a-amylase in V. mungo cotyledons are discussed. MATERIALS AND METHODSPlant Material for RNA Preparation. We used only detached cotyledons because of their high ability of a-amylase synthesis as described previously (7). Vigna mungo dry cotyledons detached from their embryonic axis were immersed in water for 6 h and then surface sterilized in 1% NaOCI solution for 5 min, rinsed with sterile water, and incubated under aseptic conditions for 4 or 5 d as described previously (7). The cotyledons were harvested, frozen with liquid N2, and stored at -20°C until used.Preparation of Poly A' RNA. All procedures were carried out in asepti...

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“…However, the developmental pathway of proplastids to mature chloroplasts can vary (Whatley, 1977). Many studies have focussed on etioplasts of dark-grown plants and their transformation to mature chloroplasts when exposed to light (Kirk and Tilney-Bassett, 1978).…”

Section: Introductionmentioning

confidence: 99%

Influence of Leaf Differentiation on the Developmental Pathway of Coleus Chloroplasts

Varkey

Nadakavukaren

1982

New Phytologist

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SUMMARYUltrastructural observations of young Coleus leaves revealed two pathways of chloroplast development within the same leaf. Developing plastids in the mesophyll cells from the basal regions of a leaf contained dense-staining inclusion bodies associated v^^ith newly forming thylakoids while these inclusion bodies were absent from the plastids in the cells of the leaf tip. Studies of the chemical nature of these inclusion bodies suggest that they are made up of proteins and possibly lipids, with no carbohydrates. The material present in the newly-forming thylakoids is similar in electron density to the inclusion bodies. The difference in chloroplast ontogeny appears to be related to the difference in cell development between the leaf tip and base.

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Variations in the Basic Pathway of Chloroplast Development

Cited by 126 publications

References 37 publications

Salinity induced structural changes in meristematic cells of barley roots

Salinity induced structural changes in meristematic cells of barley roots

Biosynthesis of α-Amylase in Vigna mungo Cotyledon

Influence of Leaf Differentiation on the Developmental Pathway of Coleus Chloroplasts

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