Wirkung von Gibberellin-A3, CCC, Ethrel and Indolessigsäure auf die Geschlechtsausprägung isolierter Blütenstandsanlagen von Lemnaceen

Abstract

Explants of in vitro cultivated inflorescence primordia of the short-day plant Lemna paucicostata exhibit masculinisation, whereas those of the long-day plant Lemna gibba exhibit feminisation. This differing developmental behaviour is exhibited on agar media containing sucrose and kinetin as the sole organic additions. The influence of various growth regulating substances on the sex expression of the isolated inflorescence primordia was investigated. Addition of CCC and of Ethrel leads to a normalisation of development in Lemna paucicostata explants by a promotion of pistil growth. In Lemna gibba both substances enhance feminisation by a further promotion of pistil growth. The same effect is brought about by the application of IAA. GA 3 , however, causes a normalisation of development or even a masculinisation of the explants of Lemna gibba , due to a promotion of stamen growth. The results lead to the conclusion that sex expression in both species is dependent on an adequate balance of hormones of the gibberellin-type and of ethylene, although the influence of other hormones should also be taken into account. Gibberellic acid always promotes the development of male flower parts, whereas ethylene (Ethrel) always promotes the development of female flower parts. The results also suggest that, in vivo , the photoperiod regulates morphogenetic processes in the flower apices by correcting the different endogenous levels of hormones in their meristems. The different day length requirements necessary to bring about the same developmental process could thus be more easily accounted for.