Question

The hormone ethylene has many different impacts on different parts of the same plant. The same is true for most plant hormones and yet essentially every cell in a plant would have the same alleles present. What are some of the factors that determine how a plant part might respond to a hormone that would allow different parts to respond differently?

Answer 1

Some factors that may influence the effect of a hormone on the plant part are:

1. The concentration of the hormone: Many plant hormones are known to have dosage-dependent effects on their target cells. This variation in response of cells to different concentrations of the hormone accounts for a part of the observed phenotypic variation.
2. The microenvironment of the cell: Different cell types in the plant are present in different micro-environments, depending on the surrounding cell types. This variation in the local environment of the cell on which a given hormone acts also determines the phenotype of the cell.
3. Signaling by other hormones: Plant hormones are known to act in concert with other plant hormones, and various final phenotypes are dependent upon signaling by two or more diffrent hormones. Therefore, phenotypic variation is also dependent upon which other hormones are acting on the target cell.