Wheat Type One Protein Phosphatase Participates in the Brassinosteroid Control of Root Growth via Activation of BES1

Abstract

Brassinosteroids (BRs) play key roles in diverse plant growth processes through a complex signaling pathway. Components orchestrating the BR signaling pathway include receptors such as kinases, transcription factors, protein kinases and phosphatases. The proper functioning of the receptor kinase BRI1 and the transcription factors BES1/BZR1 depends on their dephosphorylation by type 2A protein phosphatases (PP2A). In this work, we report that an additional phosphatase family, type one protein phosphatases (PP1), contributes to the regulation of the BR signaling pathway. Co-immunoprecipitation and BiFC experiments performed in Arabidopsis plants overexpressing durum wheat TdPP1 showed that TdPP1 interacts with dephosphorylated BES1, but not with the BRI1 receptor. Higher levels of dephosphorylated, active BES1 were observed in these transgenic lines upon BR treatment, indicating that TdPP1 modifies the BR signaling pathway by activating BES1. Moreover, ectopic expression of durum wheat TdPP1 lead to an enhanced growth of primary roots in comparison to wild-type plants in presence of BR. This phenotype corroborates with a down-regulation of the BR-regulated genes CPD and DWF4. These data suggest a role of PP1 in fine-tuning BR-driven responses, most likely via the control of the phosphorylation status of BES1.

Rice protein phosphatase 1 regulatory subunits OsINH2 and OsINH3 participate actively in growth and adaptive responses under abscisic acid

“…Our results are consistent with the involvement of PP1R3 in stress responses, as Zhang et al (2020) reported a mutation in PP1R3 not only results in decreased seed germination and cotyledon greening but also retards seedling growth under ABA. Moreover, under exogenous brassinosteroid (BR), longer roots of TdPP1 overexpressing transgenic lines (Bradai et al, 2021) confirmed the participation of PP1 under hormonal stress in crops. Similarly, NaCl tolerance of OsPP1a overexpression genotypes (Liao et al, 2016) highlighted that PP1 could also rescue plants under abiotic stresses.…”

Maize ZmBES1/BZR1-3 and -9 Transcription Factors Negatively Regulate Drought Tolerance in Transgenic Arabidopsis

“…Adjusting the root system architecture is one important clue for plants to conquer stress due to the root being the first defensive line to adapt to their environment [ 35 , 36 ]. Moreover, bes1-D had a shorter meristem size in the root [ 37 ]. BES1 regulates the vascular cell development in the root apex and root growth mediated by the type one protein phosphatases [ 37 , 38 ].…”

“…Moreover, bes1-D had a shorter meristem size in the root [ 37 ]. BES1 regulates the vascular cell development in the root apex and root growth mediated by the type one protein phosphatases [ 37 , 38 ]. Besides, BES1 acts to promote seedling growth in the auxin pathway [ 39 ].…”

Type One Protein Phosphatase Regulates Fixed-Carbon Starvation-Induced Autophagy by Dephosphorylating ATG13a to Facilitate ATG1a-ATG13a Formation in Arabidopsis

“…In addition, OsPP1a and TdPP1a play potential roles in the salt stress response in rice and wheat, respectively (Liao et al, 2016;Bradai et al, 2018). The latest study shows TdPP1 participates in the brassinosteroid control of root growth via activation of BRI1-EMS suppressor1 (BES1) (Bradai et al, 2021). In this research, we found that TOPP, as a novel regulator of the ATG1-ATG13 complex in Arabidopsis, promotes autophagy by dephosphorylating ATG13a and modulating the formation of the ATG1a-ATG13a complex under fixed-carbon (C) starvation.…”