UUAT1 Is a Golgi-Localized UDP-Uronic Acid Transporter That Modulates the Polysaccharide Composition of Arabidopsis Seed Mucilage

Saéz-Aguayo, Susana; Rautengarten, Carsten; Temple, Henry; Sanhueza, Dayán; Ejsmentewicz, Troy; Sandoval-Ibáñez, Omar; Doñas, Daniela; Parra-Rojas, Juan Pablo; Ebert, Berit; Lehner, Arnaud; Mollet, Jean‐Claude; Dupree, Paul; Scheller, Henrik Vibe; Heazlewood, Joshua L.; Reyes, Francisca; Orellana, Ariel

doi:10.1105/tpc.16.00465

Cited by 56 publications

(58 citation statements)

References 81 publications

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“…Wild‐type or ice1 cDNA from developing seeds at globular, heart, torpedo or green cotyledon (Green Cot) stage were examined using quantitative PCR for the expression of ZHOUPI ( ZOU ) , MYB 118 , the embryo‐specific At2g23230 , ABSCISIC ACID INSENSITIVE 4 ( ABI 4 ), ABSCISIC ACID INSENSITIVE 5 ( ABI 5 ), ABSCISIC ACID INSENSITIVE 3 ( ABI 3 ), the 9‐ cis ‐epoxycarotenoid dioxygenases NCED 6 and NCED 9 and the abscisic acid 8′‐hydroxylases CYP 707A1 and CYP 707A2 that were normalised against a clathrin adaptor complex subunit ( CACS , At5g46630; Nelson et al ., ). Similar data were found for normalisation against the control gene At4g12590 (Saez‐Aguayo et al ., ). The wild type (Col) is represented as black diamonds and ice1‐2 as grey squares with a hatched line.…”

Section: Resultsmentioning

confidence: 97%

ICE1 and ZOU determine the depth of primary seed dormancy in Arabidopsis independently of their role in endosperm development

et al. 2019

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SummarySeed dormancy is a widespread and key adaptive trait that is essential for the establishment of soil seed banks and prevention of pre‐harvest sprouting. Herein we demonstrate that the endosperm‐expressed transcription factors ZHOUPI (ZOU) and INDUCER OF CBF EXPRESSION1 (ICE1) play a role in determining the depth of primary dormancy in Arabidopsis. We show that ice1 or zou increases seed dormancy and the double mutant has an additive phenotype. This increased dormancy is associated with increased ABA levels, and can be separated genetically from any role in endosperm maturation because loss of ABA biosynthesis or DELAY OF GERMINATION 1 reverses the dormancy phenotype without affecting the aberrant seed morphology. Consistent with these results, ice1 endosperms had an increased capacity for preventing embryo greening, a phenotype previously associated with an increase in endospermic ABA levels. Although ice1 changes the expression of many genes, including some in ABA biosynthesis, catabolism and/or signalling, only ABA INSENSITIVE 3 is significantly misregulated in ice1 mutants. We also demonstrate that ICE1 binds to and inhibits expression of ABA INSENSITIVE 3. Our data demonstrate that Arabidopsis ICE1 and ZOU determine the depth of primary dormancy during maturation independently of their effect on endosperm development.

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Section: Resultsmentioning

confidence: 97%

ICE1 and ZOU determine the depth of primary seed dormancy in Arabidopsis independently of their role in endosperm development

et al. 2019

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“…This enables the plant to alter the composition of pectin in response to environmental requirements by modulating the nucleotide sugar concentrations in the Golgi lumen. To date, a specific UDP‐Ara p transporter has not been reported; however, a UDP‐GlcA/UDP‐GalA transporter (UUAT1) was recently shown to also transport UDP‐Ara p , albeit with lower efficiency (Saez‐Aguayo et al ., ). Accumulation of intracellular UDP‐Ara p correlates with increased Ara in galactan (Figure ), and therefore suggests a route for UDP‐Ara p to enter the Golgi lumen, possibly through the UUAT1 transporter.…”

Section: Discussionmentioning

confidence: 97%

Bifunctional glycosyltransferases catalyze both extension and termination of pectic galactan oligosaccharides

et al. 2018

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Pectins are the most complex polysaccharides of the plant cell wall. Based on the number of methylations, acetylations and glycosidic linkages present in their structures, it is estimated that up to 67 transferase activities are involved in pectin biosynthesis. Pectic galactans constitute a major part of pectin in the form of side-chains of rhamnogalacturonan-I. In Arabidopsis, galactan synthase 1 (GALS1) catalyzes the addition of galactose units from UDP-Gal to growing β-1,4-galactan chains. However, the mechanisms for obtaining varying degrees of polymerization remain poorly understood. In this study, we show that AtGALS1 is bifunctional, catalyzing both the transfer of galactose from UDP-α-d-Gal and the transfer of an arabinopyranose from UDP-β-l-Ara to galactan chains. The two substrates share a similar structure, but UDP-α-d-Gal is the preferred substrate, with a 10-fold higher affinity. Transfer of Ara to galactan prevents further addition of galactose residues, resulting in a lower degree of polymerization. We show that this dual activity occurs both in vitro and in vivo. The herein described bifunctionality of AtGALS1 may suggest that plants can produce the incredible structural diversity of polysaccharides without a dedicated glycosyltransferase for each glycosidic linkage.

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“…Proper function of Golgi is essential for myriad cellular processes including biosynthesis of noncellulosic cell wall polysaccharides (Oikawa et al, 2013;Reyes & Orellana, 2008). Transporters have been described in Golgi membranes to deliver the substrates required for polysaccharide biosynthesis, such as the UDP-Uronic acid transporter, UUAT1; and the GDP-fucose transporter, GFT1 (Rautengarten et al, 2016;Saez-Aguayo et al, 2017). Some transporters, such as the Ca 2+ pump and H +-ATPase AVP2, function in maintaining ionic homeostasis essential for enzymatic action including Golgi-localized glycosyltransferases in cell wall biosynthesis (Drozdowicz, Kissinger, & Rea, 2000;Ordenes, Reyes, Wolff, & Orellana, 2002).…”

Section: Discussionmentioning

confidence: 99%

Golgi‐localized cation/proton exchangers regulate ionic homeostasis and skotomorphogenesis in Arabidopsis

Wang

Tang

Yang

et al. 2018

Plant Cell & Environment

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Multiple transporters and channels mediate cation transport across the plasma membrane and tonoplast to regulate ionic homeostasis in plant cells. However, much less is known about the molecular function of transporters that facilitate cation transport in other organelles such as Golgi. We report here that Arabidopsis KEA4, KEA5, and KEA6, members of cation/proton antiporters‐2 (CPA2) superfamily were colocalized with the known Golgi marker, SYP32‐mCherry. Although single kea4,5,6 mutants showed similar phenotype as the wild type under various conditions, kea4/5/6 triple mutants showed hypersensitivity to low pH, high K+, and high Na+ and displayed growth defects in darkness, suggesting that these three KEA‐type transporters function redundantly in controlling etiolated seedling growth and ion homeostasis. Detailed analysis indicated that the kea4/5/6 triple mutant exhibited cell wall biosynthesis defect during the rapid etiolated seedling growth and under high K+/Na+ condition. The cell wall‐derived pectin homogalacturonan (GalA)3 partially suppressed the growth defects and ionic toxicity in the kea4/5/6 triple mutants when grown in the dark but not in the light conditions. Together, these data support the hypothesis that the Golgi‐localized KEAs play key roles in the maintenance of ionic and pH homeostasis, thereby facilitating Golgi function in cell wall biosynthesis during rapid etiolated seedling growth and in coping with high K+/Na+ stress.

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UUAT1 Is a Golgi-Localized UDP-Uronic Acid Transporter That Modulates the Polysaccharide Composition of Arabidopsis Seed Mucilage

Cited by 56 publications

References 81 publications

ICE1 and ZOU determine the depth of primary seed dormancy in Arabidopsis independently of their role in endosperm development

ICE1 and ZOU determine the depth of primary seed dormancy in Arabidopsis independently of their role in endosperm development

Bifunctional glycosyltransferases catalyze both extension and termination of pectic galactan oligosaccharides

Golgi‐localized cation/proton exchangers regulate ionic homeostasis and skotomorphogenesis in Arabidopsis

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