Overexpression and loss-of-function at TIME FOR COFFEE results in similar phenotypes in diverse growth and physiological responses

Abstract

Plant experience diurnal changes in their environment that can be anticipated and responded to via the circadian clock. Integration of external signals by this clock ensures metabolic homeostasis and ultimately enhances fitness. TIME FOR COFFEE (TIC) is known to be associated to the circadian clock, being required to maintain rhythmic period and amplitude, and to regulate clock-driven physiological responses. The molecular function of TIC has so far only been studied with loss-of-function mutants. The biochemical activity of TIC remains elusive. To learn more about TIC in diverse physiological processes, here we generated TIC overexpressing plants (TICox) and characterized their impact on plant growth, development, and circadianclock activity. TICox plants displayed phenotypic similarity with tic mutants. This included defects in leaf morphology, the developmental transition from the vegetative to reproductive phase, and circadian-clock function. These observations allowed us to hypothesize that TIC is an element of protein complexes that are involved in global biological processes.