The AtSUC2 Promoter: A Powerful Tool to Study Phloem Physiology and Development

Stadler, Ruth; Sauer, Norbert

doi:10.1007/978-1-4939-9562-2_22

Cited by 14 publications

(12 citation statements)

References 103 publications

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“…Upon phloem unloading, the large PD size-exclusion-limit in SiLs (Stadler et al, 2005) would accommodate passive diffusion of translocated ∼13-15 kDa siRNAs (21-nt duplexes) well-below the free-GFP’s 27 kDa. RNAi movement, at least in pSU2 -based systems, is thus the likely manifestation of predominantly vasculature-dependent long-distance siRNA transport, as indeed previously anticipated (Stadler and Sauer, 2019).…”

Section: Discussionsupporting

confidence: 74%

“…S3) and in stems of the phenotypically analogous JAP3 line based on pSUC2 -driven expression of a PHYTOENE DESATURASE(PDS)- derived IR transgene (Fig.2b; (Smith et al, 2007). This lack-of-silencing in stems is striking because potent pSUC2 activity in those tissues (Stadler and Sauer, 2019) enables retrieval of apoplastic photoassimilates potentially leaked during source-to-sink transport (Ayre et al, 2003). Aiding the photoassimilates’ long-distance transport is the well-documented symplasmic isolation of the SE-CC-complex(SECCC) in stems, where few and low-conductivity PDs remaining at the CC-phloem parenchyma(PP) interface minimize photoassimilates’ dispersion from the inner vascular cylinder to outer-stem tissues (Kempers and van Bel, 1997; Kempers et al, 1998).…”

Section: Resultsmentioning

confidence: 99%

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In plantadynamics, transport-biases and endogenous functions of mobile siRNAs inArabidopsis

Brosnan¹,

Devers²,

Sarazin³

et al. 2021

Preprint

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In RNA interference (RNAi), small-interfering (si)RNAs processed from double-stranded RNA guide ARGONAUTE(AGO) proteins to silence sequence-complementary RNA/DNA. Plant RNAi can propagate locally and systemically, but despite recent mechanistic advances, basic questions/hurdles remain unaddressed. For instance, RNAi is inferred to diffuse through plasmodesmata, yet how its dynamics in planta compares with that of established symplastic-diffusion markers remains unknown. Also unknown is why select siRNA species, or size-classes thereof, are recovered in RNAi-recipient tissues, yet only under some experimental settings. Finally, RNAi shootward movement in micro-grafted Arabidopsis -necessary to study its presumptive transgenerational effects- has not been achieved thus far and endogenous functions of mobile RNAi remain scarcely documented. Focusing on non-amplified RNAi in Arabidopsis, we show here that (i) transgenic RNAi-movement, although symplasmic, only partially recapitulates the diffusion pattern of free GFP in planta, (ii) the presence/absence of specific AGOs in incipient/traversed/recipient tissues likely explains the apparent siRNA-selectivity observed during vascular movement, (iii) stress application allows endo-siRNA translocation against the shoot-to-root phloem flow, and (iv) mobile endo-siRNAs generated from a single inverted-repeat(IR) locus, have the potential to regulate hundreds of transcripts. Our results close important knowledge-gaps, rationalize previously-noted inconsistencies between mobile RNAi settings, and provide a framework for functional endo-siRNA studies.

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Section: Discussionsupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

In plantadynamics, transport-biases and endogenous functions of mobile siRNAs inArabidopsis

Brosnan¹,

Devers²,

Sarazin³

et al. 2021

Preprint

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“…The mpl1-1 allele also attenuated the ssi2 -conferred enhanced resistance to the GPA (Louis et al ., 2010b). Here, we demonstrate that GPA infestation results in the upregulation of MPL1 promoter activity in the phloem and MPL1 expression from the phloem- specific SUCROSE-PROTON SYMPORTER 2 ( SUC2 ) promoter (Stadler and Sauer, 2019) is sufficient to restore resistance to the GPA in the mpl1-1 background. We provide physiological and genetic evidence that suggests an interplay between MPL1 and OPDA signaling in defense against the GPA.…”

Section: Introductionmentioning

confidence: 87%

“…A pMDC85 derivative (Gottwald et al ., 2000) in which the 35S promoter was replaced by the phloem-specific SUC2 promoter (Stadler and Sauer, 2019), was used to generate the SUC2 p: MPL1 chimera in which the MPL1 coding sequence is expressed from the SUC2 promoter. The LR clonase system (https://www.thermofisher.com) was used to mobilize the MPL1 coding sequence contained in a pCR8 vector (Louis et al ., 2010b) into the pMDC85- SUC2 p vector.…”

Section: Methodsmentioning

confidence: 99%

Interplay between MYZUS PERSICAE-INDUCED LIPASE 1 and OPDA signaling in controlling green peach aphid infestation on Arabidopsis thaliana

Archer

Mondal

Behera

et al. 2022

Preprint

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MYZUS PERSICAE-INDUCED LIPASE1 (MPL1) encodes a lipase in Arabidopsis thaliana that is required for controlling infestation by the green peach aphid (GPA; Myzus persicae), an important phloem sap-consuming insect pest. Previously, we demonstrated that MPL1 expression was upregulated in response to GPA infestation, and GPA fecundity was higher on the mpl1 mutant, compared to the wild-type (WT), and lower on 35S:MPL1 plants that constitutively expressed MPL1 from the 35S promoter. Here, we show that the MPL1 promoter is active in the phloem and expression of the MPL1 coding sequence from the phloem-specific SUC2 promoter is sufficient to restore resistance to the GPA in the mpl1 mutant. The GPA infestation-associated upregulation of MPL1 requires CYCLOPHILIN 20-3 (CYP20-3), which encodes a 12-oxo-phytodienoic acid (OPDA)-binding protein that is involved in OPDA signaling and is required for controlling GPA infestation. OPDA promotes MPL1 expression to limit GPA fecundity, a process that requires CYP20-3 function. These results along with our observation that constitutive expression of MPL1 from the 35S promoter restores resistance to the GPA in the cyp20-3 mutant, and MPL1 feedbacks to limit OPDA levels in GPA-infested plants, suggest that an interplay between MPL1, OPDA, and CYP20-3 contributes to resistance to the GPA

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“…Specific expression of SUC2 in the SE/CC is controlled at the transcriptional level through regulation by transcription factors recognizing cis ‐regulatory elements in the SUC2 gene promoter (Schneidereit et al ., 2008). The SUC2 promoter has been widely used in studies of biological processes associated with SE/CC (Stadler & Sauer, 2019). However, we know nothing about control of the specific expression of SWEETs in PP/BS cells or about how this control relates to the evolution of vascular plants.…”

Section: Introductionmentioning

confidence: 99%

Two evolutionarily duplicated domains individually and post‐transcriptionally control SWEET expression for phloem transport

Zhang

Wang

et al. 2021

New Phytologist

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Summary Cell type‐specific gene expression is critical for the specialized functions within multicellular organisms. In Arabidopsis, SWEET11 and SWEET12 sugar transporters are specifically expressed in phloem parenchyma (PP) cells and are responsible for sucrose efflux from the PP, the first step of a two‐step apoplasmic phloem‐loading strategy that initiates the long‐distance transport of sugar from leaves to nonphotosynthetic sink tissues. However, we know nothing about what determines the PP cell‐specific expression of these SWEETs. Sequence deletions, histochemical β‐glucuronidase (GUS) analysis, cross‐sectioning, live‐cell imaging, and evolutionary analysis were used to elucidate domains responsible for PP specificity, while a Förster resonance energy transfer (FRET) sensor‐based transport assay was used to determine whether substrate specificity coevolved with PP specificity. We identified two domains in the Arabidopsis SWEET11 coding sequence that, along with its promoter (including 5′ UTR), regulate PP‐specific expression at the post‐transcriptional level, probably involving RNA‐binding proteins. This mechanism is conserved among vascular plants but independent of transport substrate specificity. We conclude that two evolutionarily duplicated coding sequence domains are essential and individually sufficient for PP‐specific expression of SWEET11. We also provide a crucial experimental tool to study PP physiology and development.

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The AtSUC2 Promoter: A Powerful Tool to Study Phloem Physiology and Development

Cited by 14 publications

References 103 publications

In plantadynamics, transport-biases and endogenous functions of mobile siRNAs inArabidopsis

In plantadynamics, transport-biases and endogenous functions of mobile siRNAs inArabidopsis

Interplay between MYZUS PERSICAE-INDUCED LIPASE 1 and OPDA signaling in controlling green peach aphid infestation on Arabidopsis thaliana

Two evolutionarily duplicated domains individually and post‐transcriptionally control SWEET expression for phloem transport

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