Plant Cells Are Not Just Green Yeast

Bassham, Diane C.; Raikhel, Natasha V.

doi:10.1104/pp.122.4.999

Cited by 45 publications

(27 citation statements)

References 14 publications

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“…Similar advances also have been made in the plant kingdom, especially in terms of ER quality control (Vitale and Denecke, 1999) and vacuolar protein sorting (Marty, 1999;Vitale and Raikhel, 1999;Bassham and Raikhel, 2000). From these studies, it has become apparent that most proteins that mediate intracellular membrane traffic in other eukaryotes also are found in plants (Robinson et al, 1998;Sanderfoot et al, 2000;Nebenführ and Staehelin, 2001).…”

Section: Discussionmentioning

confidence: 74%

“…From these studies, it has become apparent that most proteins that mediate intracellular membrane traffic in other eukaryotes also are found in plants (Robinson et al, 1998;Sanderfoot et al, 2000;Nebenführ and Staehelin, 2001). Interestingly, despite these similarities at the molecular level, the secretory system in plants is organized differently and performs different functions (Bassham and Raikhel, 2000;Nebenführ and Staehelin, 2001). As we have demonstrated here, these similarities and differences also are reflected in the response of the plant Golgi apparatus to the toxin BFA.…”

Section: Discussionmentioning

confidence: 99%

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Reevaluation of the Effects of Brefeldin A on Plant Cells Using Tobacco Bright Yellow 2 Cells Expressing Golgi-Targeted Green Fluorescent Protein and COPI Antisera

et al. 2002

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Brefeldin A (BFA) causes a block in the secretory system of eukaryotic cells by inhibiting vesicle formation at the Golgi apparatus. Although this toxin has been used in many studies, its effects on plant cells are still shrouded in controversy. We have reinvestigated the early responses of plant cells to BFA with novel tools, namely, tobacco Bright Yellow 2 (BY-2) suspension-cultured cells expressing an in vivo green fluorescent protein-Golgi marker, electron microscopy of high-pressure frozen/freeze-substituted cells, and antisera against At ␥ -COP, a component of COPI coats, and AtArf1, the GTPase necessary for COPI coat assembly. The first effect of 10 g/mL BFA on BY-2 cells was to induce in Ͻ 5 min the complete loss of vesicle-forming At ␥ -COP from Golgi cisternae. During the subsequent 15 to 20 min, this block in Golgi-based vesicle formation led to a series of sequential changes in Golgi architecture, the loss of distinct Golgi stacks, and the formation of an endoplasmic reticulum (ER)-Golgi hybrid compartment with stacked domains. These secondary effects appear to depend in part on stabilizing intercisternal filaments and include the continued maturation of cis -and medial cisternae into trans -Golgi cisternae, as predicted by the cisternal progression model, the shedding of trans -Golgi network cisternae, the fusion of individual Golgi cisternae with the ER, and the formation of large ER-Golgi hybrid stacks. Prolonged exposure of the BY-2 cells to BFA led to the transformation of the ER-Golgi hybrid compartment into a sponge-like structure that does not resemble normal ER. Thus, although the initial effects of BFA on plant cells are the same as those described for mammalian cells, the secondary and tertiary effects have drastically different morphological manifestations. These results indicate that, despite a number of similarities in the trafficking machinery with other eukaryotes, there are fundamental differences in the functional architecture and properties of the plant Golgi apparatus that are the cause for the unique responses of the plant secretory pathway to BFA. INTRODUCTIONThe fungal toxin brefeldin A (BFA) has been used as an experimental tool to block secretion in a wide variety of eukaryotic cells (Fujiwara et al., 1988;Satiat-Jeunemaitre et al., 1996). In plants, it has been shown to block the secretion of cell wall polysaccharides and proteins (Driouich et al., 1993;Schindler et al., 1994;Kunze et al., 1995) as well as the transport of soluble proteins to the vacuole (Holwerda et al., 1992;Gomez and Chrispeels, 1993). In animals, the BFA-induced block of secretion is accompanied by a structural disruption of the secretory system, most notably involving the Golgi apparatus, which becomes extensively tubulated and eventually fuses with the endoplasmic reticulum (ER) (Sciaky et al., 1997;Hess et al., 2000). In contrast, the responses of plant cells to BFA range from a loss of ciscisternae and a concomitant increase in trans -cisternae to the accumulation of Golgi membranes in highly vesicul...

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Reevaluation of the Effects of Brefeldin A on Plant Cells Using Tobacco Bright Yellow 2 Cells Expressing Golgi-Targeted Green Fluorescent Protein and COPI Antisera

et al. 2002

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“…In plants, there are two different types of vacuoles: lytic vacuoles and storage vacuoles. Storage vacuoles are unique to plants, and extensive studies have suggested that the molecular mechanism by which proteins are transported to plant lytic vacuoles may be more complex than that in yeast (Bassham and Raikhel, 2000). The PVC, which probably is a target for AtVTI11-containing vesicles, seems to mediate traffic to lytic vacuoles.…”

Section: Zig/sgr4 Is a Snare Atvti11mentioning

confidence: 99%

SGR2, a Phospholipase-Like Protein, and ZIG/SGR4, a SNARE, Are Involved in the Shoot Gravitropism of Arabidopsis

et al. 2002

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In higher plants, the shoot and the root generally show negative and positive gravitropism, respectively. To elucidate the molecular mechanisms involved in gravitropism, we have isolated many shoot gravitropism mutants in Arabidopsis. The sgr2 and zig/sgr4 mutants exhibited abnormal gravitropism in both inflorescence stems and hypocotyls. These genes probably are involved in the early step(s) of the gravitropic response. The sgr2 mutants also had misshapen seed and seedlings, whereas the stem of the zig/sgr4 mutants elongated in a zigzag fashion. The SGR2 gene encodes a novel protein that may be part of a gene family represented by bovine phosphatidic acid-preferring phospholipase A1 containing a putative transmembrane domain. This gene family has been reported only in eukaryotes. The ZIG gene was found to encode AtVTI11, a protein that is homologous with yeast VTI1 and is involved in vesicle transport. Our observations suggest that the two genes may be involved in a vacuolar membrane system that affects shoot gravitropism. INTRODUCTIONPlants settle in their place of germination through their lifetime and cannot escape the various environmental stimuli to which they are exposed. Consequently, plants have evolved many mechanisms by which they can sense and adapt themselves to various environmental changes. Gravitropism is one of those important environmental responses, particularly for land plants. This is the response that the plant makes when it is laid flat on the ground, namely, the shoot curves up (negative gravitropism) and the root curves down (positive gravitropism). This response is necessary to position the plant so that its leaves face the source of light energy and its roots can take up water and various nutrients.A number of physiological and cytological studies using many different species of plants have demonstrated that amyloplasts that accumulate starch are involved in gravity perception as statoliths and that auxin is involved in the asymmetric growth between the upper and lower tissue of the responding organ that results in the gravitropic curvature (Sack, 1991; Kaufman et al., 1995). These studies also have suggested that various signal molecules, such as Ca 2 ϩ , calmodulin, and inositol 1,4,5-triphosphate, and pH change are involved in the signal transduction that generates the gravitropic response (Belyavskaya, 1996;Sinclair and Trewavas, 1997;Perera et al., 1999;Scott and Allen, 1999;Fasano et al., 2001).To elucidate the molecular mechanism of the gravitropic response in higher plants, many mutants with aberrant root or shoot gravitropism have been isolated from Arabidopsis (Firn et al., 2000;Tasaka et al., 2001). With respect to root or hypocotyl gravitropism, most of the mutants that are abnormal in this function also respond abnormally to auxin treatment. This suggests that a number of auxin-related genes are involved in this response. These include the AUX1 ( AUXIN RESISTANT 1 ) and EIR1/AGR1/PIN2 ( ETHYLENE INSENSITIVE ROOT 1/AGRAVITROPIC 1/PIN-FORMED 2 ) genes, which appear to be in...

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“…This latter result implies that heterologous systems may not always furnish the same molecular environments for plant-origin membrane transporters. It has been observed that plant proteins often are nonfunctional or mislocalized in heterologous expression systems, which has resulted in their attribution of molecular or cellular functions that they do not have in plants (Bassham and Raikhel, 2000;Noh et al, 2001;Geisler and Murphy, 2006).…”

Section: Introductionmentioning

confidence: 99%

P-Glycoprotein4 Displays Auxin Efflux Transporter–Like Action in Arabidopsis Root Hair Cells and Tobacco Cells

2007

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ATP binding cassette (ABC) transporters transport diverse substrates across membranes in various organisms. However, plant ABC transporters have only been scantily characterized. By taking advantage of the auxin-sensitive Arabidopsis thaliana root hair cell and tobacco (Nicotiana tabacum) suspension cell systems, we show here that Arabidopsis P-glycoprotein4 (PGP4) displays auxin efflux activity in plant cells. Root hair cell-specific overexpression of PGP4 (PGP4ox) and known auxin efflux transporters, such as PGP1, PGP19, and PIN-FORMEDs, decreased root hair elongation, whereas overexpression of the influx transporter AUXIN-RESISTANT1 enhanced root hair length. PGP4ox-mediated root hair shortening was rescued by the application of auxin or an auxin efflux inhibitor. These results indicate that the increased auxin efflux activity conferred by PGP4 reduces auxin levels in the root hair cell and consequently inhibits root hair elongation. PGP4ox in tobacco suspension cells also increased auxin efflux. PGP4 proteins were targeted to the plasma membrane of Arabidopsis root hair cells and tobacco cells without any clear subcellular polarity. Brefeldin A partially interfered with the trafficking of PGP4 reversibly, and this was rescued by pretreatment with auxin. These results suggest that PGP4 is an auxin efflux transporter in plants and that its trafficking to the plasma membrane involves both BFA-sensitive and -insensitive pathways.

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Plant Cells Are Not Just Green Yeast

Cited by 45 publications

References 14 publications

Reevaluation of the Effects of Brefeldin A on Plant Cells Using Tobacco Bright Yellow 2 Cells Expressing Golgi-Targeted Green Fluorescent Protein and COPI Antisera

Reevaluation of the Effects of Brefeldin A on Plant Cells Using Tobacco Bright Yellow 2 Cells Expressing Golgi-Targeted Green Fluorescent Protein and COPI Antisera

SGR2, a Phospholipase-Like Protein, and ZIG/SGR4, a SNARE, Are Involved in the Shoot Gravitropism of Arabidopsis

P-Glycoprotein4 Displays Auxin Efflux Transporter–Like Action in Arabidopsis Root Hair Cells and Tobacco Cells

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