Molecular analysis of nuclear genes in somatic bybrids

Abstract

This paper reviews recent developments in the use of molecular probes for analyzing the genetic makeup of somatic hybrids. Successful application of somatic hybridization to the interspecific transfer of traits encoded in the nucleus is still having limited success. A major difficulty is hybrid infertility, particularly in hybrids between sexually incompatible species. The formation of asymmetric hybrids is being explored as an approach for improving hybrid fertility. Evaluation of the degree of chromosome elimination and chromosome stability and instability in asymmetric hybrids is difficult when the traditional approaches of chromosome counting and isozyme analysis are used. Two new approaches are resolving this difficulty. The use of species‐specific repetitive DNA probes in dot blotting and in situ hybridization to chromosomes is providing quantitative data on chromosome elimination and allows detection of translocations. Use of restriction fragment length polymorphism (RFLP) probes for analysis of hybrids between genetically mapped species makes it possible to account for the presence or absence of individual chromosomes and chromosomes arms. Wider use of such molecular probes should greatly improve our understanding of the genetics of both symmetric and asymmetric somatic hybrids and may lead to new strategies for the effective interspecific transfer of nucleus‐encoded traits by protoplast fusion.