Three <i>SAC1</i>‐like genes show overlapping patterns of expression in <i>Arabidopsis</i> but are remarkably silent during embryo development

Despres, Barbara; Bouissonnie, F.; Wu, Hui‐Ju; Gomord, Véronique; Guilleminot, Jocelyne; Grellet, Françoise; Berger, Frédéric; Delseny, Michel; Devic, Martine

doi:10.1046/j.1365-313x.2003.01720.x

Cited by 35 publications

(49 citation statements)

References 80 publications

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“…Currently, nine putative PI phosphatases have been identified in Arabidopsis by sequence homology (Zhong and Ye, 2003;Szumlanski and Nielsen, 2009b). Three of these, SAC6, SAC7, and SAC8, show the closest similarity to yeast PI(4)P phosphatase, and all three are able to complement the yeast mutant, suggesting they are the PI phosphatases that use PI(4)P as a substrate (Despres et al, 2003;Zhong and Ye, 2003;Szumlanski and Nielsen, 2009b). Of these three, only SAC7 (RHD4) has been studied in detail, and it has been shown to regulate root hair tip growth .…”

Section: Discussionmentioning

confidence: 99%

TheArabidopsisStem Cell Factor POLTERGEIST Is Membrane Localized and Phospholipid Stimulated

Gagne

Clark

2010

The Plant Cell

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Stem cell maintenance and differentiation are tightly regulated in multicellular organisms. In plants, proper control of the stem cell populations is critical for extensive postembryonic organogenesis. The Arabidopsis thaliana protein phosphatase type 2C proteins POLTERGEIST (POL) and PLL1 are essential for maintenance of both the root and shoot stem cells. Specifically, POL and PLL1 are required for proper specification of key asymmetric cell divisions during stem cell initiation and maintenance. POL and PLL1 are known to be integral components of the CLE/WOX signaling pathways, but the location and mechanisms by which POL and PLL1 are regulated within these pathways are unclear. Here, we show that POL and PLL1 are dual-acylated plasma membrane proteins whose membrane localization is required for proper function. Furthermore, this localization places POL and PLL1 in proximity of the upstream plasma membrane receptors that regulate their activity. Additionally, we find that POL and PLL1 directly bind to multiple lipids and that POL is catalytically activated by phosphatidylinositol (4) phosphate [PI(4)P] in vitro. Based on these results, we propose that the upstream receptors in the CLE/WOX signaling pathways may function to either limit PI(4)P availability or antagonize PI(4)P stimulation of POL/PLL1. Significantly, the findings presented here suggest that phospholipids play an important role in promoting stem cell specification.

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Section: Discussionmentioning

confidence: 99%

TheArabidopsisStem Cell Factor POLTERGEIST Is Membrane Localized and Phospholipid Stimulated

Gagne

Clark

2010

The Plant Cell

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“…The AtSAC1b gene has recently been characterized as a polyphosphoinositide phosphatase that modulates cellular phosphoinositide levels (Despres et al, 2003). To confirm the involvement of the AtSAC1b/IBS2 gene in BABA responsiveness, we have tested a sequence-indexed T-DNA insertion line from the Salk Institute collection (accession Col-0) for BABA-induced sterility.…”

Section: Ibs2 Encodes a Phosphoinositide Phosphatasementioning

confidence: 99%

“…The sequence-indexed mutant s-031243 with a T-DNA insertion at nearly the same locus displayed a similar level of BABA insensitivity, confirming the involvement of AtSAC1b/IBS2 in BABA-induced sterility ( Figures 1A and 1B). The predicted translation product of AtSAC1b/IBS2 shows 50% identity with the SAC1 protein of yeast (Despres et al, 2003). This yeast protein functions as a polyphosphoinositide phosphatase, which converts phosphatidylinositol (PtdIns) 3-phosphate, PtdIns 4-phosphate, and PtdIns 3,5-biphosphate into PtdIns (Guo et al, 1999).…”

Section: Involvement Of Phosphoinositide Signaling In Baba-induced Prmentioning

confidence: 99%

“…In yeast, null mutations of the SAC1 gene result in enhanced accumulation of PtdIns(4)P and PtdIns(4,5)P 2 , affecting protein trafficking and organization of the actin cytoskeleton (Hama et al, 1999;Foti et al, 2001;Schorr et al 2001). Interestingly, Despres et al (2003) recently demonstrated that transformation of a yeast sac1 null-mutant with the Arabidopsis AtSAC1b/IBS2 gene results in full complementation of the sac1 mutant phenotype. This demonstrates that the AtSAC1b/IBS2 protein in Arabidopsis fulfills similar cellular functions as the SAC1 protein in yeast.…”

Section: Involvement Of Phosphoinositide Signaling In Baba-induced Prmentioning

confidence: 99%

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Dissecting the β-Aminobutyric Acid–Induced Priming Phenomenon in Arabidopsis

et al. 2005

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Plants treated with the nonprotein amino acid β-aminobutyric acid (BABA) develop an enhanced capacity to resist biotic and abiotic stresses. This BABA-induced resistance (BABA-IR) is associated with an augmented capacity to express basal defense responses, a phenomenon known as priming. Based on the observation that high amounts of BABA induce sterility in Arabidopsis thaliana, a mutagenesis screen was performed to select mutants impaired in BABA-induced sterility (ibs). Here, we report the isolation and subsequent characterization of three T-DNA–tagged ibs mutants. Mutant ibs1 is affected in a cyclin-dependent kinase–like protein, and ibs2 is defective in AtSAC1b encoding a polyphosphoinositide phosphatase. Mutant ibs3 is affected in the regulation of the ABA1 gene encoding the abscisic acid (ABA) biosynthetic enzyme zeaxanthin epoxidase. To elucidate the function of the three IBS genes in plant resistance, the mutants were tested for BABA-IR against the bacterium Pseudomonas syringae pv tomato, the oomycete Hyaloperonospora parasitica, and BABA-induced tolerance to salt. All three ibs mutants were compromised in BABA-IR against H. parasitica, although to a different extent. Whereas ibs1 was reduced in priming for salicylate (SA)-dependent trailing necrosis, mutants ibs2 and ibs3 were affected in the priming for callose deposition. Only ibs1 failed to express BABA-IR against P. syringae, which coincided with a defect in priming for SA-inducible PR-1 gene expression. By contrast, ibs2 and ibs3 showed reduced BABA-induced tolerance to salt, which correlated with an affected priming for ABA-inducible gene expression. For all three ibs alleles, the defects in BABA-induced sterility and BABA-induced protection against P. syringae, H. parasitica, and salt could be confirmed in independent mutants. The data presented here introduce three novel regulatory genes involved in priming for different defense responses.

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“…Three Arabidopsis SAC proteins have been demonstrated to be able to rescue the cold-sensitive and inositol auxotroph yeast sac1-null mutant strain, and like yeast Sac1p, they are localized in the endoplasmic reticulum (ER) (Despres et al, 2003). However, the roles of SAC domain proteins in plant cellular functions and plant growth and development remain unknown.…”

Section: Introductionmentioning

confidence: 99%

Mutation of SAC1, an Arabidopsis SAC Domain Phosphoinositide Phosphatase, Causes Alterations in Cell Morphogenesis, Cell Wall Synthesis, and Actin Organization

et al. 2005

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SAC (for suppressor of actin) domain proteins in yeast and animals have been shown to modulate the levels of phosphoinositides, thereby regulating several cellular activities such as signal transduction, actin cytoskeleton organization, and vesicle trafficking. Nine genes encoding SAC domain-containing proteins are present in the Arabidopsis thaliana genome, but their roles in plant cellular functions and plant growth and development have not been characterized. In this report, we demonstrate the essential roles of one of the Arabidopsis SAC domain proteins, AtSAC1, in plant cellular functions. Mutation of the AtSAC1 gene in the fragile fiber7 (fra7) mutant caused a dramatic decrease in the wall thickness of fiber cells and vessel elements, thus resulting in a weak stem phenotype. The fra7 mutation also led to reduced length and aberrant shapes in fiber cells, pith cells, and trichomes and to an alteration in overall plant architecture. The AtSAC1 gene was found to be expressed in all tissues in elongating organs; however, it showed predominant expression in vascular tissues and fibers in nonelongating parts of stems. In vitro activity assay demonstrated that AtSAC1 exhibited phosphatase activity toward phosphatidylinositol 3,5-biphosphate. Subcellular localization studies showed that AtSAC1 was colocalized with a Golgi marker. Truncation of the C terminus by the fra7 mutation resulted in its localization in the cytoplasm but had no effect on phosphatase activity. Furthermore, examination of the cytoskeleton organization revealed that the fra7 mutation caused the formation of aberrant actin cables in elongating cells but had no effect on the organization of cortical microtubules. Together, these results provide genetic evidence that AtSAC1, a SAC domain phosphoinositide phosphatase, is required for normal cell morphogenesis, cell wall synthesis, and actin organization.

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Three SAC1‐like genes show overlapping patterns of expression in Arabidopsis but are remarkably silent during embryo development

Cited by 35 publications

References 80 publications

TheArabidopsisStem Cell Factor POLTERGEIST Is Membrane Localized and Phospholipid Stimulated

TheArabidopsisStem Cell Factor POLTERGEIST Is Membrane Localized and Phospholipid Stimulated

Dissecting the β-Aminobutyric Acid–Induced Priming Phenomenon in Arabidopsis

Mutation of SAC1, an Arabidopsis SAC Domain Phosphoinositide Phosphatase, Causes Alterations in Cell Morphogenesis, Cell Wall Synthesis, and Actin Organization

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