TANDEM ZINC-FINGER/PLUS3 Is a Key Component of Phytochrome A Signaling

Abstract

Phytochrome A (phyA) is the primary plant photoreceptor responsible for perceiving and mediating various responses to farred (FR) light and is essential for survival in canopy shade. In this study, we identified two Arabidopsis thaliana mutants that grew longer hypocotyls in FR light. Genetic analyses showed that they were allelic and their FR phenotypes were caused by mutations in the gene named TANDEM ZINC-FINGER/PLUS3 (TZP), previously shown to encode a nuclear protein involved in blue light signaling and phyB-dependent regulation of photoperiodic flowering. We show that the expression of TZP is dramatically induced by light and that TZP proteins are differentially modified in different light conditions. Furthermore, we show that TZP interacts with both phyA and FAR-RED ELONGATED HYPOCOTYL1 (FHY1) and regulates the abundance of phyA, FHY1, and ELONGATED HYPOCOTYL5 proteins in FR light. Moreover, our data indicate that TZP is required for the formation of a phosphorylated form of phyA in the nucleus in FR light. Together, our results identify TZP as a positive regulator of phyA signaling required for phosphorylation of the phyA photoreceptor, thus suggesting an important role of phosphorylated phyA in inducing the FR light response.

Differential phosphorylation of the N‐terminal extension regulates phytochrome B signaling

“…Our knowledge about phosphorylation of Arabidopsis phytochromes is rather limited. Recent reports also showed that Arabidopsis phyA is phosphorylated in planta (Zhang et al, 2018;Zhou et al, 2018). Recent reports also showed that Arabidopsis phyA is phosphorylated in planta (Zhang et al, 2018;Zhou et al, 2018).…”

“…It was demonstrated, that Arabidopsis phyA, phyB and phyD autophosphorylate and have kinase activity towards their interaction partner PHYTOCHROME INTERACTING FACTOR 3 (PIF3) in vitro (Shin et al, 2016). Recent reports also showed that Arabidopsis phyA is phosphorylated in planta (Zhang et al, 2018;Zhou et al, 2018).…”

ABRE‐BINDING FACTORS play a role in the feedback regulation of ABA signaling by mediating rapid ABA induction of ABA co‐receptor genes

“…Immunoblotting was performed as described previously (Zhang et al, 2018). Briefly, Arabidopsis seedlings were ground to a fine powder and were then homogenized in an extraction buffer containing 50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 10 mM MgCl 2 , 0.1% Tween 20, 1 mM phenylmethylsulfonyl fluoride, 40 mM MG132 and 1 9 complete protease inhibitor cocktail (Roche).…”

Genome and time-of-day transcriptome of Wolffia australiana link morphological extreme minimization with un-gated plant growth

“…Also light regulated growth is controlled at some level by two distinct types of nuclear photobodies, one of which is defined by TANDEM ZINC KNUCKLE/PLUS3 (TZP) . TZP mutants in Arabidopsis are smaller while overexpression results in large plants that don't stop growing, consistent with it being a central integrator of light (PHYA) signaling into plant growth (Loudet et al 2008;Huang et al 2016;Zhang et al 2018). The loss of TZP (a BUSCO gene) in Wolffia, and its retention in Spirodela, suggests that a different growth regulation pathway exists or that growth is uncoupled from light in Wolffia.…”