The Importance of Polyploidy in Modern Apple Breeding

Abstract

During the past 25 or 30 years the science of apple breeding has gone through a period of change from the basic orthodox methods of plant hybridization to a new series of techniques which involve not only the genes — the units which control heredity — but also the chromosomes on which these genes are located. When the chromosomes are considered, rather than the genes, the important factor is the number of chromosomes which are contained in the cells of a particular plant. This variation in number may cause a change in the characteristics of the individual, even though there is no alteration in the particular genes which it possesses. These changes may show up as an increase in size, more vigor, large plant parts (including fruit), changes in flowering time and date of fruit ripening, differences in flesh texture and keeping quality and variations in many other, perhaps less obvious ways.