Die Adventivknospen an den Wedeln vonCystopteris bulbifera (L.) Bernhardi

Ohne Zusammenfassung     

Die spinnwebigen Haare an den Blattspitzen vonSempervivum arachnoideum L.

Ohne Zusammenfassung     

Die spinnwebigen Haare an den Blattspitzen vonSempermvum arachnoideum L.

Ohne Zusammenfassung     

Die Steuerung der Proteinsynthese durch Blaulicht und Hellrot in den Vorkeimen vonDryopteris Filix-Mas (L.) Schott

Ohne ZusammenfassungMit 8 Textabbildungen     

Die Nahorientierung der Mehlschwalbe (Delichon urbica L.)

Ohne Zusammenfassung     

An elicitor-induced cDNA from aerial yam (Dioscorea bulbifera L.) encodes a pathogenesis-related type 4 protein

We established Dioscorea bulbifera (aerial yam) cell suspension cultures to study the expression of defense-related genes upon elicitation with the yam pathogenic ascomycete Colletotrichum gloeosporioides. The induction of phenylalanine-ammonia lyase (PAL) mRNA, coding for a key enzyme involved in phytoalexin biosynthesis, was observed upon elicitation. Using RT-PCR, we isolated an elicited cDNA clone with an open reading frame of 453 nucleotides which showed high homology to cDNA sequences of pathogenesis-related proteins belonging to the PRP-4 group. Yam PRP-4 expression is increased in elicited cell cultures as well as in elicited leaves, and is encoded by a small multigene family. This is the first example for the cloning of a cDNA that might be involved in defense reactions of yam plants. Received: December 1997 / Revision received: June 1998 / Accepted: November 1998     

Die Klebstoffhaare an den Antheren vonCyclanthera pedata (Cucurbitaceae)

The highly specialized, two-celled hairs fringing the anthers ofCyclanthera pedata (L.)Schrad. and its relatives aid in pollination by producing a glue which sticks the coarse pollen grains onto insect visitors. This was proven by direct observations, confirming older assumptions. The adhesive is extruded from the big basal cell which bursts upon the slightest touch to the small top cell.—Turgor and, possibly, swelling pressure of the sticky material, are responsible for plasmoptysis and ejaculation. Cell contraction is due to tension of cuticular clips and, to a minor degree, to elasticity of the pectinic wall. A preformed apical dehiscence line disrupts when the top cell is bent aside.—The anthers hairs of a flower develop synchronously. From light and electron microscopic observations, the adhesive appears not to be a product of internal secretion. It originates from the endopolyploid giant nucleus of the basal cell, which finally degenerates by liquefying and swelling. The numerous peculiar elaioplasts apparently do not contribute to the hair's function.—The anther hairs are homologous to, and possibly have evolved from the so-called explosion hairs occurring on the green parts of manyCucurbitaceae.

Herrn Professor Dr.Walter Leinfellner zum 70. Geburtstag gewidmet.     

The apparent loss of tissue culture competence during leaf differentiation in yams (Dioscorea bulbifera L.)

Explants taken from the leaves of yams (Dioscorea bulbifera L.) at different stages of development were cultured in vitro on a checkerboard using various combinations and/or concentrations of auxin (2,4-d) and cytokinin (6-BAP). An addition of cytokinin to the culture media was not essential for callus induction from explants derived from young leaves in the very early stages of expansion. When the leaves expanded further they required cytokinin and the requirement increased considerably during expansion. Explants taken from fully expanded leaves were no longer able to proliferate, even when extremely high concentrations of cytokinins were applied. Callus grown from highly immature leaves was able to continue proliferating in the absence of cytokinin when subcultured. Callus, that initially required cytokinin in the medium, proliferated in the absence of exogenous cytokinin when subcultured.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid - 6-BAP 6-benzylamino purine - 1-NAA 1-naphthalenacetic acid     

Die Entwicklung des Prothalliums vonAnogramma leptophylla (L.) Lk

Ohne ZusammenfassungEndlieh ist es meine angenehme Pflicht, Herrn Hofrat Professor R. v. Wettstein für die Überlassung des Materiales und für die Anregung, die er mir zuteil werden ließ, sowie Herrn Prof. O. Porsch für seine äußerst freundliche Unterstützung, meinen herzlichsten Dank zu sagen.     

Die geographische Variation desPhylloscopus trochilus (L.)

Ohne Zusammenfassung     

Ueber den Kopfanhang des Truthuhns (Meleagris gallopavo L.)

Ohne Zusammenfassung