Received September 3, 2007
Accepted September 29, 2007
The 14-3-3 proteins µ and 
influence transition to flowering and early phytochrome response
John D. Mayfield , Kevin M. Folta , Anna-Lisa Paul , and Robert J. Ferl *
Plant Molecular and Cellular Biology Program and Horticultural Sciences Department, University of Florida, Gainesville, FL 32611
* Corresponding author; email: robferl{at}ufl.edu.
14-3-3 proteins regulate a diverse set of biological responses but developmental phenotypes associated with 14-3-3 mutations have not been described in plants. Here physiological and biochemical tests demonstrate interactions between 14-3-3s and the well-established mechanisms that govern light sensing and photoperiodic flowering control. Plants featuring homozygous disruption of 14-3-3 isoforms 
and µ display defects in light sensing and/or response. Mutant plants flower late and exhibit long hypocotyls under red light, with little effect under blue or far-red light. The long hypocotyl phenotype is consistent with a role for 14-3-3 and µ in phytochrome B signaling. Yeast two-hybrid and co-immunoprecipitation assays indicate that 14-3-3 and µ protein physically interact with CONSTANS, a central regulator of the photoperiod pathway. Together, these data indicate a potential role for specific 14-3-3 isoforms in affecting photoperiodic flowering via interaction with CONSTANS, possibly as integrators of light signals sensed through the phytochrome system.
