A mutation is a genetic change resulting in a structural modification in the DNA on the chromosome. The mutation may result from a point mutation in a single gene that changes its function, or it may be due to a rearrangement, deletion or duplication of genes on the chromosome.
In most cases, a mutation is detrimental but sometimes, the mutation can improve the horticultural characteristics of a plant.
Examples include changes in growth rate, fruit characteristics and leaf or flower color.
A base change from A to T
A loss of CCG CAA
A bud-sport is a mutation that occurs in plants that appears as a sudden change in the genetic traits of a branch. These "sports" may affect fruit (color, shape or maturity), tree structure, time to bloom, leaf shape or color, and many other traits.
Some of these mutations have become commercially important like - red colored fruit sports of apple, 'Ruby Red' grapefruit and many traits in ornamental plants.
A pink flowering sport (mutation) on a white crabapple.