The physiology of petal senescence which is not initiated by ethylene

Summary

Es ist also kein Zweifel, dass schon mit dem Beginn des Aufblühens das Schicksal der Blütenblätter besiegelt ist und die Prozesse eingeschaltet werden, deren Ablauf nach kürzerer oder längerer Zeit das Leben der Blütenblätter begrenzt.

(There is, therefore, no doubt that the fate of the petals has already been sealed by the beginning of flower opening, and that the processes which limit the life of the petals, be it a shorter or longer period, have been initiated.)

W. Schumacher, 1953. Planta 42: 42–55

Introduction

Petals have an important function: the attraction of pollinators. Conspicuous petals are, therefore, only found in plants that are pollinated by animals. Attraction of pollinators is terminated by wilting of the petals, by abscission of turgid petals, or by petal colour changes. A change in colour, if it occurs, normally precedes wilting or abscission.

Schumacher (1953), quoted above, expressed what has become a widely accepted hypothesis: the functional life of the petals is genetically determined at an early phase of development, resulting in the expression of genes that are involved in cellular breakdown of the petals in the species that show wilting, in the changes in the abscission zone cells in the species that show abscission, and in the colour changes if these occur. The nature of the physiological processes leading to cellular degradation, and those leading to abscission is only partially known.