Insight Into the Genetic Cause of Sports or Reversions in Dwarf Lagerstroemia

Miniature or dwarf crapemyrtles (Lagerstroemia) have been increasing in popularity since they were first introduced in the 1990s. However, some lineages have a tendency to send up “sports” or larger, faster-growing branches. These sports are characterized by more vigorous growth, earlier and more abundant flowers, and much greater seed set than the dwarf plant from which they came. Although the sport can be pruned off, if left alone it will eventually overgrow the miniature phenotype. Such a trait has obvious disadvantages for nursery and landscape settings. We studied the role of giberellic acid (GA) as a possible cause of these anomalies. The effect of GA on plant growth (in vitro and whole plant) was determined, and molecular comparisons between sporting and non-sporting sectors were also made. Knowledge of what is causing this anomaly will be useful in selecting plants that do not have this trait. It could also be useful in gaining insight into genetic factors that control dwarfing in crapemyrtles.