Plastid RNA

Fig. 1. Northern blot of plastid RNAs from sections of 6 day-old dark-grown barley leaves Plastids were isolated from the following leaf segments base to 1 cm (lane 1), 1 to 2 cm (lane 2), 2 to 3 cm (lane 3), 3 to 4.5 cm (lane 4), 4.5 to 6 cm (lane 5), 6 to 8 cm from the leaf base (lane 6). Total plastid nucleic acid extracted from an equal number of plastids was applied to nylon blots and probed with radiolabel DNA probes for RNA from psaA-psaB rbcL, psbA and 16S rDNA as described previously (20).

A Accumulation of plastid RNAs in dark-grown plants. 

The polypeptide patterns of greening barley indicate that these PSI - polypeptides are S5mthesized diiring the first six hours of gree-ning(15). Therefore, poly-A+ and plastid RNA were isolated and the presence of the transcripts for SUII, the SUIII and the Chl - apoprotein 1 was studied by tn vitvo translation and following immunoprecipitation with monoclonal antibodies. In the wild - type as well as in the mutant these transcripts are present (FIG.Ia-c). The translation products for the SUII and SUIII show an apparent of about 23 and 30 kD respectively and for the Chl -apoprotein 1 an apparent of about 69 kD. 

Fig. 5. RNA of plastid fraction (washed 1000g pellet) isolated from leaves maintained in darkness or illuminated for 3 hours after absorption of P-phosphate. RNA was extracted and centrifuged as described in legend for Fig. 3, but fractions here were collected manually and optical densities at 260 m/ were determined after dilution. (The two heavier RNA s, when obtained from maize chloro-plasts purified on a sucrose density gradient, are approximately 22 S and 17 S. The apparent base composition of these RNA s is approximately 25% adenine, 32% guanine, 20% uracil, and 23% cytosine these values are based on the distribution of radioactivity, after paper electrophoresis, among AMP, GMP, UMP, and CMP obtained by alkaline hydrolysis of plastid RNA s prepared from sucrose gradient purified plastids of maize leaves supplied P-phosphate.)...

In a series of investigations in which the incorporation of into plastid RNA was studied by sucrose density gradient analyses of RNA extracted from the organelles, it was found that the effect of light was inductive in the sense that the specific activity of the RNA obtained from plastids of etiolated leaves illuminated for 30 minutes and then returned to darkness for 90 minutes was approximately the same as that of plastids from leaves illuminated continuously for 2 hours. 

The Effect op Illumination op Etiolated Maize Leaves ON Plastid RNA Polymerase Activity... 

The activity of RNA polymerase in proplastids from chloramphenicol-treated leaves maintained in darkness is lower than in proplastids from controls. Furthermore, illumination of chloramphenicol-treated etiolated leaves results in some increase in plastid RNA polymerase, but the response is much smaller than that exhibited by plastids from illuminated controls (Table 4). These observations suggest that RNA polymerase is forming and decaying in etiolated maize proplastids in darkness but that the rate of formation is increased by light. On the other hand, the activity of the soluble RNA ploymerase found outside... 

Fig. 9. Titration of plastid RNA pol)merase from illuminated and unillumi-nated dark-grown maize leaves with calf thymus DNA.

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... 

An entirely different possibility depends upon indications that enzymes in general, and some of the enzymes discussed here in particular, vary in longevity. Plastid RNA polymerase, ribulose diphos-... 

The data presented here show that shortly after etiolated leaves have been illuminated, the rate of synthesis of plastid RNA and certain plastid enzymes increases. Mego and Jagendorf (1961) found that the protein content per plastid increases markedly as etiolated bean leaves become green. Williams and Novelli (1964) found ribosomes of illuminated leaves from dark-grown maize to be more active than ribosomes from unilluminated leaves in the in capacity to incorporate amino acids into trichloroacetic acid-insoluble materials, but the increased activity could be detected only after a few hours of illumination or after 1 hour in the light followed by 1 hour of darkness. Thus,... 

The order Caryophyllales embraces families which have a characteristic ultrastructure of their sieve-element plastids, namely, the P-III subtype (104). In addition, the widespread occurrence of C4 photosynthesis as well as DNA-RNA hybridization data support this taxonomic treatment (23). Within this order, the occurrence of betalains is restricted to nine of the eleven families of the Caryophyllales. The two exceptions, Caryophyllaceae and Molluginaceae, produce anthocyanins instead. There is controversy regarding the phylogenetic importance of this phenomenon (105). It has been suggested that a division of the Caryophyllales into two phylogenetic lines is possible, the betalain-producing Chenopodiineae and the anthocyanin-producing Caryophyllineae (103) (see Scheme 9). The presence of betalains has been an important criterion in the classification of questionable taxa as demonstrated by various examples (13). 

In the chloroplasts of land plants, besides rRNA and tRNA genes, the sprA gene for the plastid 218-bp RNA was reported. Targeted deletion of this gene has no eflFect on the phenotype of the plant in a growth chamber however, in the field the plants exhibit stunted growth. ... 

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