PHO1 expression in guard cells mediates the stomatal response to abscisic acid in Arabidopsis

Département de Biologie Moléculaire Végétale, Biophore, Université de Lausanne, CH-1015 Lausanne, Switzerland CEA/CNRS, Laboratoire de Biologie du Développement des Plantes, UMR 7265, Université Aix-Marseille, St Paul Lez-Durance F-13108, France Institute for Molecular Plant Physiology and Biophysics, University Würzburg, Julius-von-Sachs Platz 2, D-97082 Würzburg, Germany.
The Plant Journal (Impact Factor: 5.97). 05/2012; 72(2):199-211. DOI: 10.1111/j.1365-313X.2012.05058.x
Source: PubMed


Stomatal opening and closing are driven by ion fluxes that cause changes in guard cell turgor and volume. This process is, in turn, regulated by environmental and hormonal signals, including light and the phytohormone abscisic acid (ABA). Here, we present genetic evidence that expression of PHO1 in guard cells of Arabidopsis thaliana is required for full stomatal responses to ABA. PHO1 is involved in the export of phosphate into the root xylem vessels and, as a result, the pho1 mutant is characterized by low shoot phosphate levels. In leaves, PHO1 was found expressed in guard cells and up-regulated following treatment with ABA. The pho1 mutant was unaffected in production of reactive oxygen species following ABA treatment, and in stomatal movements in response to light cues, high extracellular calcium, auxin, and fusicoccin. However, stomatal movements in response to ABA treatment were severely impaired, both in terms of induction of closure and inhibition of opening. Micro-grafting a pho1 shoot scion onto wild-type rootstock resulted in plants with normal shoot growth and phosphate content, but failed to restore normal stomatal response to ABA treatment. PHO1 knockdown using RNA interference specifically in guard cells of wild-type plants caused a reduced stomatal response to ABA. In agreement, specific expression of PHO1 in guard cells of pho1 plants complemented the mutant guard cell phenotype and re-established ABA sensitivity, although full functional complementation was dependent on shoot phosphate sufficiency. Together, these data reveal an important role for phosphate and the action of PHO1 in the stomatal response to ABA.

Download full-text


Available from: Alain Vavasseur, Oct 21, 2014
  • Source
    • "Interestingly, ABA-dependent regulation of stomatal closure responds to mutation of the phosphate transporter PHO1 and the vacuolar H+-ATPase subunit A (Zimmerli et al., 2012; Zhang et al., 2013). Again, these results support interaction and co-regulation of ion homeostasis in guard cells via ion transport, ABA signaling, and regulation of stomatal aperture (Zimmerli et al., 2012; Zhang et al., 2013). Intriguingly, the transporter ZIFL1 (Induced Facilitator-Like 1) mediates potassium fluxes and has a dual function in regulating both cellular auxin transport and stomatal closure (Remy et al., 2013). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Tolerance of plants to abiotic stressors such as drought and salinity is triggered by complex multicomponent signaling pathways to restore cellular homeostasis and promote survival. Major plant transcription factor families such as bZIP, NAC, AP2/ERF, and MYB orchestrate regulatory networks underlying abiotic stress tolerance. Sucrose non-fermenting 1-related protein kinase 2 and mitogen-activated protein kinase pathways contribute to initiation of stress adaptive downstream responses and promote plant growth and development. As a convergent point of multiple abiotic cues, cellular effects of environmental stresses are not only imbalances of ionic and osmotic homeostasis but also impaired photosynthesis, cellular energy depletion, and redox imbalances. Recent evidence of regulatory systems that link sensing and signaling of environmental conditions and the intracellular redox status have shed light on interfaces of stress and energy signaling. ROS (reactive oxygen species) cause severe cellular damage by peroxidation and de-esterification of membrane-lipids, however, current models also define a pivotal signaling function of ROS in triggering tolerance against stress. Recent research advances suggest and support a regulatory role of ROS in the cross talks of stress triggered hormonal signaling such as the abscisic acid pathway and endogenously induced redox and metabolite signals. Here, we discuss and review the versatile molecular convergence in the abiotic stress responsive signaling networks in the context of ROS and lipid-derived signals and the specific role of stomatal signaling.
    Full-text · Article · Apr 2014 · Frontiers in Plant Science
  • Source
    • "AthPHO1; H10 was reported to be induced by numerous stresses, including local wounding responses [15,16]. Recently, AthPHO1 has been suggested to play an important role in the stomatal response to abscisic acid (ABA); its expression in guard cells is induced by ABA treatment [17]. Therefore, plant PHO1 genes have undergone a functional diversification and acquired diverse roles beyond Pi transport and homeostasis. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background PHOSPHATE1 (PHO1) gene family members have diverse roles in plant growth and development, and they have been studied in Arabidopsis, rice, and Physcomitrella. However, it has yet to be described in other plants. Therefore, we surveyed the evolutionary patterns of genomes within the plant PHO1 gene family, focusing on soybean (Glycine max) due to its economic importance. Results Our data show that PHO1 genes could be classified into two major groups (Class I and Class II). Class I genes were only present and expanded in dicotyledonous plants and Selaginella moellendorffii; Class II genes were found in all land plants. Class I sequence losses in other lineages may be attributed to gene loss after duplication events in land plant evolution. Introns varied from 7 to 14, and ancestral state reconstruction analyses revealed that genes with 13 introns were ancestral, thus suggesting that the intron loss was a chief constituent of PHO1 gene evolution. In the soybean genome, only 12 PHO1-like genes (GmaPHO1) were detected at the mRNA level. These genes display tissue-specific or tissue-preferential expression patterns during soybean plant and fruit development. Class I genes were more broadly expressed than Class II. GmaPHO1 genes had altered expression in response to salt, osmotic, and inorganic phosphate stresses. Conclusions Our study revealed that PHO1 genes originated from a eukaryotic ancestor and that two major classes formed in land plants. Class I genes are only present in dicots and lycophytes. GmaPHO1genes had diverse expression patterns in soybean, indicating their dramatic functional diversification.
    Full-text · Article · May 2013 · BMC Evolutionary Biology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Inorganic phosphate (Pi) availability in soils is often low and heterogeneous. Therefore, plants have evolved numerous adaptations to maintain Pi homeostasis that are regulated by both local and systemic signaling pathways. The level of sophistication in Pi signaling is exemplified by the presence of a key systemic signaling circuit that has been elucidated in the past decade. This circuit appears conserved among angiosperms and involves a phloem-mobile microRNA that targets a root-specific E2 conjugase. Recent advances regarding this circuit and its regulators, as well as additional systemic signaling factors, are the focus of this chapter.
    No preview · Chapter · Jan 2013
Show more