Involvement of 14-3-3 protein GRF9 in root growth and response under polyethylene glycol-induced water stress

Abstract

Plant 14-3-3 proteins are phosphoserine-binding proteins that regulate a wide array of targets via direct protein-protein interactions. In this study, the role of a 14-3-3 protein, GRF9, in plant response to water stress was investigated. Arabidopsis wild-type, GRF9-deficient mutant (grf9), and GRF9-overexpressing (OE) plants were treated with polyethylene glycol (PEG) to induce mild water stress. OE plant showed better whole-plant growth and root growth than the wild type under normal or water stress conditions while the grf9 mutant showed worse growth. In OE plants, GRF9 favours the allocation of shoot carbon to roots. In addition, GRF9 enhanced proton extrusion, mainly in the root elongation zone and root hair zone, and maintained root growth under mild water stress. Grafting among the wild type, OE, and grf9 plants showed that when OE plants were used as the scion and GRF9 was overexpressed in the shoot, it enhanced sucrose transport into the root, and when OE plants were used as rootstock and GRF9 was overexpressed in the root, it caused more release of protons into the root surface under water stress. Taken together, the results suggest that under PEG-induced water stress, GRF9 is involved in allocating more carbon from the shoot to the root and enhancing proton secretion in the root growing zone, and this process is important for root response to mild water stress.

Chloroplast Calcium Signaling in the Spotlight

“…Interestingly, AtGRF9, a Ca 2+ -regulated 14-3-3 protein, although not predicted to be located in chloroplasts, has been demonstrated to be present in many compartments, including plastids. This regulatory protein is involved in root and leaf development under water stress (He et al, 2015) and leaf development in general (Omidbakhshfard et al, 2018), but its role in chloroplasts has not yet been explored. The presence of members of protein families involved in Ca 2+ transport/sensing supports the idea of a core-machinery determining the observed Ca 2+ transients in the chloroplast stroma, and putatively in the thylakoid lumen as well.…”

“…The N-terminal domain (NTD) of AtcMCU harbours motifs rich in acidic residues, one of which (107-118) playing a role in Ca 2+ uptake by cMCU, as demonstrated by mutagenesis studies (D107A/E118K mutant) and Ca 2+ uptake assays in an aequorinbased E. coli system (Teardo et al, 2019). Two groups independently set up the same system to study MCU activity, Mayfield et al, 2012;He et al, 2015;Liu et al, 2017;Omidbakhshfard et al, 2018 At4g08810 AtSUB1 Calcium binding protein plastid, nucleus, ER, Golgi, Golgi cryptochrome and phytochrome coaction Guo et al, 2001;Parsons et al, 2012 At4g34070 namely that exploiting E. coli stably expressing aequorin (Teardo et al, 2019) or the fluorescent Ca 2+ reporter GCaMP2 (Fan et al, 2018). This valuable tool allows a quick screening of the effect of MCU residues' mutations and of chemical modulators on the Ca 2+ flux-mediating activity and may become a method of choice for further structure-function studies.…”

A Member of the 14-3-3 Gene Family in Brachypodium distachyon, BdGF14d, Confers Salt Tolerance in Transgenic Tobacco Plants

“…Cotton ( Gossypium hirsutum ) and Arabidopsis thaliana plants overexpressing the 14-3-3 gene AtGF14λ (Yan et al, 2004) and A. thaliana plants overexpressing the 14-3-3 gene AtGRF9 (He et al, 2015) each showed improved drought tolerance. On the other hand, a 14-3-3λ and 14-3-3κ double mutant showed enhanced salt resistance (Zhou et al, 2014).…”

Componentes genéticos que afetam a via de direcionamento de proteínas organelares em <i>Arabidopsis thaliana</i>

“…A localização das 14-3-3 em diversos compartimentos sub-celulares demonstra seu potencial regulatório em toda a célula (DE LILLE et al, 2001; e sua função biológica é principalmente interagir com proteínas cliente específicas e causar um efeito que altera a cliente, que estão envolvidas em diversas funções. As 14-3-3 estão envolvidas com diversos processos regulatórios como resposta a estresse, transdução de sinais, controle do ciclo celular e apoptose (FERL et al, 2002;FORD et al, 1994;HE et al, 2015;VAN HEMERT et al, 2001).…”

“…Arabidopsis thaliana cujas funções conhecidas são alocação de carbono para crescimento da raiz sob estresse hídrico leve(HE et al, 2015), desenvolvimento dos cloroplastos (MAYFIELD; PAUL; FERL, 2012), sinalização para o florescimento via sistema fotossensível, ao interagir com CONSTANS, um regulador central da via de fotoperíodo(MAYFIELD et al, 2007) e respostas em adaptação ao estresse por calor intenso(DOBRÁ et al, 2015). A proteína GRF9 (F4IP55_ARATH) possui 276 aminoácidos e 30,96 kDa.…”