ORCID Profile
0000-0002-7556-1211
Current Organisations
Australian National University
,
VIB
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Publisher: Oxford University Press (OUP)
Date: 08-01-2016
DOI: 10.1104/PP.15.01872
Publisher: Wiley
Date: 2018
DOI: 10.1002/PLD3.31
Abstract: Homeostasis of metabolism and regulation of stress‐signaling pathways are important for plant growth. The metabolite 3′‐phosphoadenosine‐5′‐phosphate (PAP) plays dual roles as a chloroplast retrograde signal during drought and high light stress, as well as a toxic by‐product of secondary sulfur metabolism, and thus, its levels are regulated by the chloroplastic phosphatase, SAL1. Constitutive PAP accumulation in sal1 mutants improves drought tolerance but can impair growth and alter rosette morphology. Therefore, it is of interest to derive strategies to enable controlled and targeted PAP manipulation that could enhance drought tolerance while minimizing the negative effects on plant growth. We systematically tested the potential and efficiency of multiple established transgenic manipulation tools in altering PAP levels in Arabidopsis. Dexamethasone (dex)‐inducible silencing of SAL1 via hpRNAi [pOpOff: SAL1 hpRNAi] yielded reduction in SAL1 transcript and protein levels, yet failed to significantly induce PAP accumulation. Surprisingly, this was not due to insufficient silencing of the inducible system, as constitutive silencing using a strong promoter to drive hpRNAi and amiRNA targeting the SAL1 transcript also failed to increase PAP content or induce a sal1 ‐like plant morphology despite significantly reducing the SAL1 transcript levels. In contrast, using dex‐inducible expression of SAL1 cDNA to complement an Arabidopsis sal1 mutant successfully modulated PAP levels and restored rosette growth in a dosage‐dependent manner. Results from this inducible complementation system indicate that plants with intermediate PAP levels could have improved rosette growth without compromising its drought tolerance. Additionally, preliminary evidence suggests that SAL1 cDNA driven by promoters of genes expressed specifically during early developmental stages such as ABA‐Insensitive 3 ( ABI3 ) could be another potential strategy for studying and optimizing PAP levels and drought tolerance while alleviating the negative impact of PAP on plant growth in sal1 . Thus, we have identified ways that can allow future dissection into multiple aspects of stress and developmental regulation mediated by this chloroplast signal.
Publisher: Proceedings of the National Academy of Sciences
Date: 18-07-2016
Abstract: Management of oxidative stress in plant chloroplasts involves signaling pathways to the nucleus that trigger stress response mechanisms. Yet, how oxidative stress is initially sensed in the chloroplast to activate accumulation of a stress signal remains enigmatic. We show that inactivation of a phosphatase, SAL1, by oxidative stress in chloroplasts controls accumulation of its substrate, as a plant stress signal. This regulatory mechanism is highly conserved across the plant kingdom and confers a second function to this metabolic enzyme as an oxidative stress sensor.
Publisher: Annual Reviews
Date: 29-04-2016
DOI: 10.1146/ANNUREV-ARPLANT-043015-111854
Abstract: The chloroplast can act as an environmental sensor, communicating with the cell during biogenesis and operation to change the expression of thousands of proteins. This process, termed retrograde signaling, regulates expression in response to developmental cues and stresses that affect photosynthesis and yield. Recent advances have identified many signals and pathways—including carotenoid derivatives, isoprenes, phosphoadenosines, tetrapyrroles, and heme, together with reactive oxygen species and proteins—that build a communication network to regulate gene expression, RNA turnover, and splicing. However, retrograde signaling pathways have been viewed largely as a means of bilateral communication between organelles and nuclei, ignoring their potential to interact with hormone signaling and the cell as a whole to regulate plant form and function. Here, we discuss new findings on the processes by which organelle communication is initiated, transmitted, and perceived, not only to regulate chloroplastic processes but also to intersect with cellular signaling and alter physiological responses.
Publisher: Oxford University Press (OUP)
Date: 13-03-2021
Abstract: Signaling events triggered by hydrogen peroxide (H2O2) regulate plant growth and defense by orchestrating a genome-wide transcriptional reprogramming. However, the specific mechanisms that govern H2O2-dependent gene expression are still poorly understood. Here, we identify the Arabidopsis Mediator complex subunit MED8 as a regulator of H2O2 responses. The introduction of the med8 mutation in a constitutive oxidative stress genetic background (catalase-deficient, cat2) was associated with enhanced activation of the salicylic acid pathway and accelerated cell death. Interestingly, med8 seedlings were more tolerant to oxidative stress generated by the herbicide methyl viologen (MV) and exhibited transcriptional hyperactivation of defense signaling, in particular salicylic acid- and jasmonic acid-related pathways. The med8-triggered tolerance to MV was manipulated by the introduction of secondary mutations in salicylic acid and jasmonic acid pathways. In addition, analysis of the Mediator interactome revealed interactions with components involved in mRNA processing and microRNA biogenesis, hence expanding the role of Mediator beyond transcription. Notably, MED8 interacted with the transcriptional regulator NEGATIVE ON TATA-LESS, NOT2, to control the expression of H2O2-inducible genes and stress responses. Our work establishes MED8 as a component regulating oxidative stress responses and demonstrates that it acts as a negative regulator of H2O2-driven activation of defense gene expression.
Publisher: Frontiers Media SA
Date: 08-08-2018
Publisher: Frontiers Media SA
Date: 2013
Publisher: eLife Sciences Publications, Ltd
Date: 21-03-2017
DOI: 10.7554/ELIFE.23361
Abstract: Organelle-nuclear retrograde signaling regulates gene expression, but its roles in specialized cells and integration with hormonal signaling remain enigmatic. Here we show that the SAL1-PAP (3′-phosphoadenosine 5′- phosphate) retrograde pathway interacts with abscisic acid (ABA) signaling to regulate stomatal closure and seed germination in Arabidopsis. Genetically or exogenously manipulating PAP bypasses the canonical signaling components ABA Insensitive 1 (ABI1) and Open Stomata 1 (OST1) priming an alternative pathway that restores ABA-responsive gene expression, ROS bursts, ion channel function, stomatal closure and drought tolerance in ost1-2. PAP also inhibits wild type and abi1-1 seed germination by enhancing ABA sensitivity. PAP-XRN signaling interacts with ABA, ROS and Ca2+ up-regulating multiple ABA signaling components, including lowly-expressed Calcium Dependent Protein Kinases (CDPKs) capable of activating the anion channel SLAC1. Thus, PAP exhibits many secondary messenger attributes and exemplifies how retrograde signals can have broader roles in hormone signaling, allowing chloroplasts to fine-tune physiological responses.
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.TPLANTS.2012.07.005
Abstract: A key plant response to drought is the accumulation of specific sets of metabolites that act as osmoprotectants, osmolytes, antioxidants, and/or stress signals. An emerging question is: how do plants regulate metabolism to balance the 'competing interests' between metabolites during stress? Recent research connects primary sulfur metabolism (e.g., sulfate transport in the vasculature, its assimilation in leaves, and the recycling of sulfur-containing compounds) with the drought stress response. In this review, we highlight key steps in sulfur metabolism that play significant roles in drought stress signaling and responses. We propose that a complex balancing act is required to coordinate primary and secondary sulfur metabolism during the drought stress response in plants.
No related grants have been discovered for Su Yin Phua.