Induction of Micronuclei by Amiprophos-Methyl and their Application for Transfer of Single, Specific Chromosomes in Plant Cells

Abstract

In mammals, a number of somatic cell genetic techniques have been developed for the transfer of genes: whole cell hybridization, microcell-mediated gene transfer (MMGT), chromosome-mediated gene transfer (CMGT) and DNA-mediated gene transfer (DMGT) (1, 2). In plants, DMGT has become realistic by the recent progress in molecular and cell biological techniques. In the case where a monogenic trait has been characterized at the molecular level, the identified gene can be cloned and transferred into plant cells via DNA vectors or by direct DNA uptake. With respect to polygenic traits or non-identified genes, fusion of whole cells (protoplasts) offers the possibility for gene transfer. However, the hybrid cell lines or plants contain several donor chromosomes and undesired characters. Moreover, such somatic hybrids constitute a complex genetic system which is difficult to manipulate experimentally. In particular, intraclonal karyo-typic heterogeneity and instability of the hybrid chromosome compliments are factors limiting their practical utility. A conceptually ideal collection of somatic hybrids would be one in which each clone of a hybrid panel retained a single, specific donor chromosome which was maintained in the population by direct selective pressure. In the case of CMGT the transferred chromosomes integrate only as fragments (2). On the other hand, MMGT provides the necessary means to transfer single, intact chromosomes.