The morphological and physiological properties of the genetic tumours from a Nicotiana interspecific hybrid.

摘要

Many plant tumours have been loosely referred to as genetic tumours when no obvious external cause was identifiable. In this study, morphology of genetic tumours was studied by scanning electron microscopy (SEM) of interspecific hybrids between N, glauca and N. langsdorffii, and the influence of exogenous phytohormones on tumour growth was examined. Genetic tumours in hybrids were first observed in the hypocotyl area and later appeared from stems as a cluster complex. In vitro, genetic tumours wereproduced 5-6 days after explant treatment near each of the cut ends. Genetic tumours were mainly composed of epidermal cells surrounded by a well developed extracellular matrix that is organized in a network linking surface cells. Globular structures containing several cells were formed from these clusters of epidermal cells. Vigorous tumorous growth from leaf discs was obtained on medium supplemented with NAA and kinetin at 0 to 10μM, but 100μM of NAA and kinetin inhibited tumour growth. Genetic tumours are therefore tissues that are disturbed in endogenous hormone balance or have altered sensitivity to hormones and response to exogenous hormones.