Control of a symmetry-breaking process in the course of the morphogenesis of plantlets of Bidens pilosa L.

A mechanism involving transport, storage and retrieval of a symmetry-breaking message controls the relative growth rate of the cotyledonary buds of plantlets of Bidens pilosa L. The asymmetry was induced by administering a few needle pricks to one cotyledon of each plant. The storage of the symmetry-breaking message was independent of the number of pricks (“all or nothing” process) and irreversible. However, various treatments could render the plants either able to retrieve the stored symmetry-breaking message (in which case, the bud opposite to the pricked cotyledon began to elongate statistically sooner than the one associated with the stimulated cotyledon) or not (both buds then had an equal chance to be the first to start to grow). The retrieval process was also associated with a temporal oscillation. At the level of the whole plants, bud growth was observed only after the removal of apical dominance, and its degree of asymmetry was expressed by use of a parameter g ranging from zero (symmetrical case) to ± 1 (full asymmetry in favor of one of the cotyledonary buds). The highest g-values observed in the present contribution were of the order of 0.5. At the cellular level, the pricking of one cotyledon caused a number of cells, which were within the meristem of the bud associated with the pricked cotyledon and were in cell-cycle phases S or G2, to undergo cellular division and then be blocked in phase G1, whereas the cells of the opposite bud were practically unchanged.

[1]  I. Tamàs,et al.  Hormonal Regulation of Apical Dominance , 1987 .

[2]  J. Garrec,et al.  The Possible Role of Potassium in the Activation of Axillary Buds of Bidens pilosus L. after Decapitation of the Apex AN EXAMINATION BY X-RAY MICROANALYSIS , 1980 .

[3]  Daniel Schwartz,et al.  Methodes Statistiques a L'Usage des Medecins et des Biologistes , 1964 .

[4]  P. Ganter,et al.  Histochimie : normale et pathologique , 1969 .

[5]  Ronald W. Davis,et al.  Rain-, wind-, and touch-induced expression of calmodulin and calmodulin-related genes in Arabidopsis , 1990, Cell.

[6]  M. Thellier,et al.  Memorization and delayed expression of regulatory messages in plants , 1984, Planta.

[7]  J. Frachisse,et al.  Transmission of a traumatic signal via a wave of electric depolarization, and induction of correlations between the cotyledonary buds in Bidens pilosus , 1985 .

[8]  V. Malý.  Lamotte, M.: Initiation aux Méthodes statistiques en biologie. (Einführung in die statistischen Methoden in der Biologie.) Masson et Cie, Paris VIe 1957, 144 S. , 1960 .

[9]  M. Desbiez,et al.  Mécanismes de «mise en mémoire» et de «rappel de mémoire» de messages morphogènes chez Bidens pilosus L. , 1986 .

[10]  E. Wagner.  Molecular basis of physiological rhythms. , 1977, Symposia of the Society for Experimental Biology.

[11]  Isabelle Stengers,et al.  La nouvelle alliance , 1979 .

[12]  M. Thellier,et al.  Do memory processes occur also in plants , 1982 .

[13]  M. Galli,et al.  Autoradiographic and Cytofluorimetric Analysis of DNA Synthesis in Endosperm and Cotyledons of Germinating Castor Bean , 1986 .

[14]  P. L. Kooman,et al.  Integration of activity in the higher plant. , 1990 .

[15]  M. Lamotte.  Initiation aux méthodes statistiques en biologie , 1960 .

[16]  M. Jaffe.  Wind and Other Mechanical Effects in the Development and Behavior of Plants, with Special Emphasis on the Role of Hormones , 1985 .