Sucrose and starch synthesis in sugar cane plant

Zusammenfassung Im Gipfelknoten des ausgereiften Zuckerrohrs liess sich die Anwesenheit eines stärkebildenden Enzyms nachweisen, während die anderen stärkefreien Teile dieser Pflanze ein sukrosebildendes Enzymsystem enthalten. Diese Befunde stehen im Einklang mit der Speicherung von Stärke im Gipfelknoten und dem Fehlen von Stärke in den übrigen sukrosehaltigen Pflanzenteilen des Zukkerrohrs.     

Role of kinetin in the dormancy ofCercis siliquastrum seeds

Summary Studies conducted onCercis siliquastrum seeds treated with kinetin confirm that this hormone does not interrupt dormancy in either whole seeds or those decoated at the radical pole. Seeds totally decoated or decoated at the cotyledon pole only demonstrated atypical germinations linked to cotyledon growth, permitting the embryo to escape the inhibitory action present in the endosperm; this does not occur when the cotyledon surface is experimentally reduced.This investigation was supported by the Italian National Research Council (C.N.R.) Project Biology of Reproduction.     

Alteration of enzyme activities in detached leaves and their counteraction by kinetin

Zusammenfassung In abgetrennten Blättern werden verschiedene Enzyme, besonders aber die Pentosephosphatcyclus-Dehydrogenasen aktiviert. Gleichzeitig steigt die Atmungsintensität an. Die Malonatsensitivität der O₂-Aufnahme nimmt ab. Die Ausbildung der obigen Stoffwechsellage kann durch Kinetin gehemmt werden.     

Chlorophyll breakdown in higher plants and algae

Leaf senescence is accompanied by the metabolism of chlorophyll (Chl) to nonfluorescent catabolites (NCCs). The pathway of Chl degradation comprises several reactions and includes the occurrence of intermediary catabolites. After removal of phytol and the central Mg atom from Chl by chlorophyllase and Mg dechelatase, respectively, the porphyrin macrocycle of pheophorbide (Pheide) a is cleaved. This two-step reaction is catalyzed by Pheide a oxygenase and RCC reductase and yields a primary fluorescent catabolite (pFCC). After hydroxylation and additional species-specific modifications, FCCs are tautomerized nonenzymically to NCCs inside the vacuole. Different subcellular compartments participate in Chl catabolism and, thus, transport processes across membranes are required. This review focuses on the catabolites and the individual reactions of Chl breakdown in higher plants. In addition, the pathway is compared to Chl conversion to red catabolites in an alga, Chlorella protothecoides. Finally, the significance and regulation of Chl degradation are discussed.     

Effect of inhibitors of protein synthesis from plants on tobacco mosaic virus infection

Summary Ricin, abrin, modeccin, gelonin andMomordica charantia inhibitor, as well as crude extracts ofBryonia dioica seeds and ofDianthus caryophyllus leaves, each inhibit protein synthesis in a rabbit reticulocyte lysate and reduce local lesion production by tobacco mosaic virus, thus resembling the effects of the pokeweed antiviral peptide.     

Effect of chloramphenicol on the expansion of isolated cotyledons ofCucurbita pepo in light and in presence of kinetin

Zusammenfassung Kotyledonen von Cucurbita-Keimlingen zeigen im Licht in Wasser eine deutliche Zunahme der Blattfläche. Durch Chloramphenicol kann dieses Flächenwachstum gehemmt werden. Die Hemmung wird durch Kinetin aufgehoben, wobei die durch Kinetin bewirkte prozentuale Zunahme der Fläche in Wasser und in Chloramphenicol enthaltenden Lösungen ungefähr gleich gross ist.     

Restoration of declining morphogenetic capacity in long term tissue cultures ofDaucus carota by kinetin

Résumé Les cultures de tissu deDaucus carota L. récemment isolées possédent une capacité embryogénique considérable. L'intensité de cette réponse morphologique décline graduellement dans les cultures subséquentes. La kinétine et, à un moindre degré, l'auxine 2,4-D rétablissent la capacité embryogénique originale dans de vieilles cultures. Les changements de l'état hormonal au cours du vieillissement des cultures pourraient tat hormonal au cours du vieillissement des cultures pourraient tre impliqués dans ces manifestations.     

Nitrogenase activity in a transfilter culture of rhizobia with a non-leguminous plant callus culture: Transfer of fixed15N2 from bacteria toPortulaca callus

Summary A transfilter culture of the non-leguminous plantPortulaca grandiflora var. JR andRhizobium sp. cowpea 32H1 was established. Using¹⁵N₂-analysis we demonstrated that¹⁵N-containing substances produced by the bacteria passed through the membrane and¹⁵N was enriched in the plant cells.Acknowledgment. The authors wish to express their gratitude to Prof. H. Marschner and Dr G. Hentschel for the determination of the nitrogen-content of our samples by the Dumasmethod and for advice on the optic emission method. Drs J. Burton, Milwaukee, Wisc., and Tjepkema, Oregon State University, are thanked for generous gifts ofRhizobium sp. cowpea 32H1. This work was supported by the DFG.     

Induction of thermosensitivity and salt sensitivity in wheat roots (Triticum aestivum) and the effect of kinetin

Zusammenfassung Die Hitzesensibilisierung von Weizenwurzelmeristemen kann durch Kältebehandlung oder Kinetinzugaben zumindest teilweise rÜckgängig gemacht werden.     

The sugar component of aranciamycin:2-O-methyl-l-rhamnose

Zusammenfassung Der Zuckerbaustein des Antibiotikums Aranciamycin ist die2-O- Methyl-l-rhamnose.

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82nd communication of the series: Metabolic Products of Microorganisms. 81st comm. see: H.Diekmann, Arch. Mikrobiol., in press (1970).