Normal segregation of allozyme markers in complex rhododendron hybrids

Abstract

Protocols were developed for visualizing enzyme polymorphisms among rhodododendrons using starch gel electrophoresis. Genetic interpretation of nine enzyme systems comprising 15 polymorphic loci was facilitated by progeny testing of interspecific hybrid populations. In 53 of 58 segregations, phenotypic ratios at these loci fit Mendelian models for single gene inheritance at the diploid level. Disomic inheritance was consistent across a diverse array of genetic backgrounds in complex hybrids averaging six species of Rhododendron per pedigree. The low frequency of segregation distortion in these highly interspecific populations was attributed to two possible mechanisms: (1) lack of significant chromosomal differentiation among the Rhododendron species involved and (2) selection for chromosomal and genetic stability over many generations of rhododendron breeding.