Plastid development

Thomas, H., Chlorophyll a symptom and a regulator of plastid development. New PhytoL, 136, 163, 1997. 

Beale, S.I., 5-Aminolevulinic acid in plants its biosynthesis, regulation and role in plastid development, Annu. Rev. Plant Physiol, 29, 95, 1978. 

Endosperm of ae du wx in a sweet corn background has a major developmental gradient typical of normal and a type-II minor gradient characteristic of du.43 Saussy43 reports that starch granule and plastid development in ae du wx is similar to that of du wx. 

Endosperm development in ae du su wx is similar to that in du su wx, with the type-II minor gradient observed and the central endosperm cavity being present by 27 days post-pollination.43 Starch granule and phytoglycogen plastid development in ae du su wx is similar to that in su, except that the quadruple mutant has greater apparent phytoglycogen content at 16 days post-pollination than does su or any other mutant combination.43 However, with development, there is increasing deterioration of the plastids and central endosperm cells.43... 

Whatley, J. B. 1978. A suggested cycle of plastid development interrelationships. New Phytol. 80, 489-502. 

Thomas H (1997) Chlorophyll A Symptom and a Regulator of Plastid Development. New Phytol 136 163... 

Plastids developed at 5 C in the presence of CL did not show the presence of PLBs after 30 h of Illumination Using immunoblot analyses we detected the presence of PCR in thylakoids isolated after 30 h of illumination This data supports previous results (7) that PCR is translocated from PLBs to the developing thylakoids during greening ... 

The two most common approaches to the investigation of chloroplast development involve either the illumination of dark-grown leaves or the study of serial sections of a monocotyledonous leaf in which there is a gradient of cellular and plastid development from the base to the apex of the leaf with the transformation from proplastid to plastid accompanied by qualitative and quantitative differences in protein composition (3, 4). Both approaches have been used in this study. 

Wien we leave photosynthesis we also leave the area in which it is easy to distinguish what each part of the cell does. As do all other organelles, the chloroplast lives in a complex environment which is controlled largely by the activity of the nucleus but to which the metabolic activities of the other organelles— including the mitochondria, the Golgi apparatus, etc., as well as the chloroplasts themselves— undoubtedly contribute. These interrelationships must be resolved before the control of plastid development will be understood. In the meantime, in order to be able to proceed with any sort of discussion, we must recall that one of the functions of the chloroplast appears to be its own maintenance. Here we must eventually come to the questions How independent is the chloroplast in maintaining itself How dependent is the plastid on activities of other portions of the cell or on information available within the nucleus in a particular species or strain ... 

In addition to pointing to one kind of mechanism for the control of plastid development this discussion also raises the question whether plastids in all species of plants have the same nutritional requirements or whether the evolution of nuclear and chloroplast genes has been independent in plants of a single class, genus, or species. That is, we do not know whether chloroplast and nuclear functions have been assorted in the same way in every kind of plant. 

These facts about the effect of illiunination on plastid development are clear and relatively unequivocal, but, except for the photoconversion of protochlorophyllide, it is hardly certain that the primary event is absorption of light by a pigment in the ehloroplasts. Until these phenomena can be demonstrated in isolated ehloroplasts, the possibility will remain that the photoeffects are initially on the metabolic activity of some other part of the cell and the development of the plastid is influenced indirectly. Thus, we can identify certain environmental factors that control plastid development in vivo but cannot be certain that the initial photo- and biochemical events occur within the plastids. 

Thus, indirect evidence is provided for another kind of control mechanism in plastid development besides starvation. The productivity of the entire biosynthetic chain of chlorophyll seems to be regulated by the activity of an enzyme early in this chain. The enzyme itself and ribonucleic acids required for its formation appear to be comparatively labile and need to be produced constantly light, somehow, affects their production. 

CONTROL MECHANISMS IN PLASTID DEVELOPMENT PLASTIO preparation-RNA... 

The changes in plastid RNA metabolism and RNA polymerase that occur during light-induced plastic development may play a role in the control of plastid development—or at least in the light-stimulated... 

The structural and chemical changes that occur during plastid development, and which have been discussed here, can be grouped into events discernible in seconds (or less), in minutes, or only after hours of illumination of dark-grown seed plants. Thus, a rough time-scale of developmental events can be established (Table 5). 

The fact that different developmental events are widely separated in time shows that a number of different controlling mechanisms must be operating during light-induced plastid development. 

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