Basal Signaling Regulates Plant Growth and Development

The term signal transduction refers to the classical paradigm where an external stimulus is sensed and initiates an increase in second messengers. Each second messenger transmits and amplifies the signal by activating a subset of downstream pathways. This complex network of interwoven downstream events ultimately converges to produce measurable responses. While the paradigms for signal transduction are well known, little consideration has been given to the second messengers in the nonstimulated cell, the basal signal, and yet, basal signals also impact plant growth and development. Basal signals are low levels of oscillating second messengers that are being sensed by the cell. These are difficult to measure and are often considered to be background noise. Not surprisingly, there is a dearth of knowledge about how plants respond to this constant flux of signaling metabolites or about how basal signals define homeostasis or contribute to species diversity. Both genetics and environment will define the basal signal of a cell. To truly understand how plants regulate growth and development, future research must focus on understanding how basal signals regulate fundamental metabolism.