Exogenous Hormone Treatments in Maize.

Plant hormones have key functions in plant morphology, physiology, and stress responses. Studies on the biology of hormones and their effect on plant physiology and metabolism are greatly facilitated by the exogenous application of these compounds. In general, methods for exogenous hormone application are easy and fast, and provide useful information about their effects in planta. Although hormone effects have been studied in several plant species, the used methods need to be tailored specifically to each species to get robust data. Maize is an established model for basic and applied research, and an excellent system for studying the effects of hormones on developmental and stress responses in a cereal crop. Different methods have been reported for the exogenous application of plant growth regulators in maize, including watering, spraying, immersion, and application to the apical whorl. These various methods are useful to analyze hormone responses at different developmental stages, in specific organs, and within tissues. As with all exogenous application assays, suitable experimental design and the inclusion of proper controls are critical factors in these methods, to obtain reliable and reproducible results. Here, we provide an overview of various methods for hormone exogenous application in maize, and technical considerations to get successful results.