Mutations

Whenever cells divide there is the possibility of genetic variability. If a mutation (a change in genetic make-up) occurs during cell division, and assuming the cell survives the mutation, the mutation is carried in all future divisions. A mutation is a sudden abnormal change in genetic order that will alter some characteristic, or it can be a change in chromosome number. The effects of mutations are not always noticeable. Most mutations will cause a plant to die or to produce undesirable qualities, such as misshapen fruit or abnormal shoots. Growers expect a small percentage of plants to undergo mutation, and they will discard them if they see them. Fortunately, the natural frequency of gene mutation is very lowabout one in a million cells for any single gene (Tortora et al. 1982). Occasionally, a mutation will create a desired effect, so scientists often induce mutations by treatment with chemicals or radiation in an effort to foster plants with improved characteristics.