scholarly journals The Rab Geranylgeranyl Transferase Beta Subunit Is Essential for Embryo and Seed Development in Arabidopsis thaliana

2021 ◽  
Vol 22 (15) ◽  
pp. 7907
Author(s):  
Joanna Rojek ◽  
Matthew R. Tucker ◽  
Michał Rychłowski ◽  
Julita Nowakowska ◽  
Małgorzata Gutkowska
Keyword(s):  
Seed Development ◽  
Auxin Transport ◽  
Rab Proteins ◽  
Vesicular Traffic ◽  
Polar Localization ◽  
Reproductive Structures ◽  
Autonomous Endosperm ◽  
Endosperm Formation ◽  
Geranylgeranyl Transferase ◽  
Unfertilized Ovules

Auxin is a key regulator of plant development affecting the formation and maturation of reproductive structures. The apoplastic route of auxin transport engages influx and efflux facilitators from the PIN, AUX and ABCB families. The polar localization of these proteins and constant recycling from the plasma membrane to endosomes is dependent on Rab-mediated vesicular traffic. Rab proteins are anchored to membranes via posttranslational addition of two geranylgeranyl moieties by the Rab Geranylgeranyl Transferase enzyme (RGT), which consists of RGTA, RGTB and REP subunits. Here, we present data showing that seed development in the rgtb1 mutant, with decreased vesicular transport capacity, is disturbed. Both pre- and post-fertilization events are affected, leading to a decrease in seed yield. Pollen tube recognition at the stigma and its guidance to the micropyle is compromised and the seed coat forms incorrectly. Excess auxin in the sporophytic tissues of the ovule in the rgtb1 plants leads to an increased tendency of autonomous endosperm formation in unfertilized ovules and influences embryo development in a maternal sporophytic manner. The results show the importance of vesicular traffic for sexual reproduction in flowering plants, and highlight RGTB1 as a key component of sporophytic-filial signaling.

scholarly journals Natural Variation in the Degree of Autonomous Endosperm Formation Reveals Independence and Constraints of Embryo Growth During Seed Development in Arabidopsis thaliana

Genetics ◽  
2008 ◽  
Vol 179 (2) ◽  
pp. 829-841 ◽  
Author(s):  
Alexander Ungru ◽  
Moritz K. Nowack ◽  
Matthieu Reymond ◽  
Reza Shirzadi ◽  
Manoj Kumar ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Seed Development ◽  
Natural Variation ◽  
Autonomous Endosperm ◽  
Endosperm Formation

scholarly journals Rab-dependent vesicular traffic affects female gametophyte development in Arabidopsis

2020 ◽  
Author(s):  
Joanna Rojek ◽  
Matthew R Tucker ◽  
Sara C Pinto ◽  
Michał Rychłowski ◽  
Małgorzata Lichocka ◽  
...  
Keyword(s):  
Female Gametophyte ◽  
Root Hairs ◽  
Rab Proteins ◽  
Gene Encoding ◽  
Gametophyte Development ◽  
Vesicular Traffic ◽  
Geranylgeranyl Transferase ◽  
Covalently Linked ◽  
Female Gametophyte Development ◽  
Female Gametogenesis

Abstract Eukaryotic cells rely on the accuracy and efficiency of vesicular traffic. In plants, disturbances in vesicular trafficking are well studied in quickly dividing root meristem cells or polar growing root hairs and pollen tubes. The development of the female gametophyte, a unique haploid reproductive structure located in the ovule, has received far less attention in studies of vesicular transport. Key molecules providing the specificity of vesicle formation and its subsequent recognition and fusion with the acceptor membrane are Rab proteins. Rabs are anchored to membranes by covalently linked geranylgeranyl group(s) that are added by the Rab geranylgeranyl transferase (RGT) enzyme. Here we show that Arabidopsis plants carrying mutations in the gene encoding the β-subunit of RGT (rgtb1) exhibit severely disrupted female gametogenesis and this effect is of sporophytic origin. Mutations in rgtb1 lead to internalization of the PIN1 and PIN3 proteins from the basal membranes to vesicles in provascular cells of the funiculus. Decreased transport of auxin out of the ovule is accompanied by auxin accumulation in tissue surrounding the growing gametophyte. In addition, female gametophyte development arrests at the uni- or binuclear stage in a significant portion of the rgtb1 ovules. These observations suggest that communication between the sporophyte and the developing female gametophyte relies on Rab-dependent vesicular traffic of the PIN1 and PIN3 transporters and auxin efflux out of the ovule.

Oxygen-depleted zones inside reproductive structures of Brassicaceae: implications for oxygen control of seed development

1999 ◽  
Vol 77 (10) ◽  
pp. 1439-1446 ◽  
Author(s):  
D. Marshall Porterfield ◽  
Anxiu Kuang ◽  
Peter J.S. Smith ◽  
Mark L. Crispi ◽  
Mary E. Musgrave
Keyword(s):  
Seed Development ◽  
Oxygen Control ◽  
Reproductive Structures

scholarly journals Seed parasitism redirects ovule development in Douglas fir

2005 ◽  
Vol 272 (1571) ◽  
pp. 1491-1496 ◽  
Author(s):  
Patrick von Aderkas ◽  
Gaëlle Rouault ◽  
Rebecca Wagner ◽  
René Rohr ◽  
Alain Roques
Keyword(s):  
Seed Development ◽  
Pseudotsuga Menziesii ◽  
Douglas Fir ◽  
Energy Reserve ◽  
Ovule Development ◽  
Parasitic Species ◽  
Seed Parasitism ◽  
Empty Seed ◽  
Unfertilized Ovules ◽  
Storage Reserves

Many parasitic species of insects complete their entire development in seeds. They feed off storage reserves within the ovule. These reserves only normally accumulate in fertilized ovules. Consequently, female insects that oviposit their eggs directly into the plant ovule need to be able to select correctly, as unfertilized ovules of conifers normally become so-called empty seed. We provide clear evidence that in conifers, seed-parasitizing insects do not need to discriminate between fertilized and unfertilized plant ovules when ovipositing their eggs. A host-specific insect, the chalcid Megastigmus spermotrophus Wachtl (Hymenoptera: Torymidae), lays its eggs in ovules of Douglas fir ( Pseudotsuga menziesii (Mirbel) Franco) before fertilization has taken place in the plant. Oviposition not only prevents the expected degeneration and death of unfertilized ovules, but it induces energy reserve accumulation. Ovules that would otherwise develop as empty seed are redirected in their development by the insect to provide food for the developing larvae. Instead of the insect exploiting normal events during seed development, the insect manipulates seed development for its own reproductive advantage.

Genomic imprinting and seed development: endosperm formation with and without sex

2001 ◽  
Vol 4 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Ueli Grossniklaus ◽  
Charles Spillane ◽  
Damian R Page ◽  
Claudia Köhler
Keyword(s):  
Seed Development ◽  
Genomic Imprinting ◽  
Endosperm Formation

scholarly journals Expression of Rab3D N135I Inhibits Regulated Secretion of ACTH in AtT-20 Cells

1998 ◽  
Vol 140 (2) ◽  
pp. 305-313 ◽  
Author(s):  
Giulia Baldini ◽  
Giovanna Baldini ◽  
Guangyi Wang ◽  
Mattew Weber ◽  
Marina Zweyer ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Membrane Trafficking ◽  
Hormone Secretion ◽  
Dense Core ◽  
Rab Proteins ◽  
Wild Type ◽  
Small Molecular Weight ◽  
Vesicular Traffic ◽  
Regulated Secretion ◽  
Dense Core Granules

Rab proteins are small molecular weight GTPases that control vesicular traffic in eucaryotic cells. A subset of Rab proteins, the Rab3 proteins are thought to play an important role in regulated exocytosis of vesicles. In transfected AtT-20 cells expressing wild-type Rab3D, we find that a fraction of the protein is associated with dense core granules. In the same cells, expression of a mutated isoform of Rab3D, Rab3D N135I, inhibits positioning of dense core granules near the plasma membrane, blocks regulated secretion of mature ACTH, and impairs association of Rab3A to membranes. Expression of Rab3D N135I does not change the levels of ACTH precursor or the efficiency with which the precursor is processed into ACTH hormone and packaged into dense core granules. We also find that cells expressing mutated Rab3D differentiate to the same extent as untransfected AtT-20 cells. We conclude that expression of Rab3D N135I specifically impairs late membrane trafficking events necessary for ACTH hormone secretion.

scholarly journals Rab GDI: a solubilizing and recycling factor for rab9 protein.

1993 ◽  
Vol 4 (4) ◽  
pp. 425-434 ◽  
Author(s):  
T Soldati ◽  
M A Riederer ◽  
S R Pfeffer
Keyword(s):  
Complex Formation ◽  
Intracellular Transport ◽  
Rab Proteins ◽  
Rab Protein ◽  
Transport Vesicles ◽  
Late Endosomes ◽  
Geranylgeranyl Transferase ◽  
Carboxy Terminal ◽  
Golgi Network

Rab proteins are thought to function in the processes by which transport vesicles identify and/or fuse with their respective target membranes. The bulk of these proteins are membrane associated, but a measurable fraction can be found in the cytosol. The cytosolic forms of rab3A, rab11, and Sec4 occur as equimolar complexes with a class of proteins termed "GDIs," or "GDP dissociation inhibitors." We show here that the cytosolic form of rab9, a protein required for transport between late endosomes and the trans Golgi network, also occurs as a complex with a GDI-like protein, with an apparent mass of approximately 80 kD. Complex formation could be reconstituted in vitro using recombinant rab9 protein, cytosol, ATP, and geranylgeranyl diphosphate, and was shown to require an intact rab9 carboxy terminus, as well as rab9 geranylgeranylation. Monoprenylation was sufficient for complex formation because a mutant rab9 protein bearing the carboxy terminal sequence, CLLL, was prenylated in vitro by geranylgeranyl transferase I and was efficiently incorporated into 80-kD complexes. Purified, prenylated rab9 could also assemble into 80-kD complexes by addition of purified, rab3A GDI. Finally, rab3A-GDI had the capacity to solubilize rab9GDP, but not rab9GTP, from cytoplasmic membranes. These findings support the proposal that GDI proteins serve to recycle rab proteins from their target membranes after completion of a rab protein-mediated, catalytic cycle. Thus GDI proteins have the potential to regulate the availability of specific intracellular transport factors.

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