Figure 4.

Model for the interactions of light signaling, circadian rhythms and auxin-regulated growth in response to T6P. The circadian clock regulates transcript levels of the growth regulator PIF4, while PIF4 protein is degraded by the 26S proteasome in response to light. Auxin induces the expression of Aux/IAA proteins as well as promoting their degradation by the 26S proteasome in a process gated by the circadian clock. Aux/IAA proteins regulate gene expression by heterodimerizing with auxin response factor (ARF) proteins. DFL1, ENP = MAB4 = NPY1 (At4g31820) and NPY5 are possible downstream targets that are involved in plant development in response to auxin as well as to light. Examples of genes whose expression was affected in otsA-expressing seedlings with increased T6P are listed in blue (upregulated) or red (downregulated). See Table 1 for list of genes.