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Biotechnological aspects of cytoskeletal regulation in plants. Biotechnol Adv 2015; 33:1043-62. [DOI: 10.1016/j.biotechadv.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 03/03/2015] [Accepted: 03/09/2015] [Indexed: 11/23/2022]
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Klepikova AV, Logacheva MD, Dmitriev SE, Penin AA. RNA-seq analysis of an apical meristem time series reveals a critical point in Arabidopsis thaliana flower initiation. BMC Genomics 2015; 16:466. [PMID: 26084880 PMCID: PMC4470339 DOI: 10.1186/s12864-015-1688-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 06/05/2015] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Floral transition is a critical event in the life cycle of a flowering plant as it determines its reproductive success. Despite extensive studies of specific genes that regulate this process, the global changes in transcript expression profiles at the point when a vegetative meristem transitions into an inflorescence have not been reported. We analyzed gene expression during Arabidopsis thaliana meristem development under long day conditions from day 7 to 16 after germination in one-day increments. RESULTS The dynamics of the expression of the main flowering regulators was consistent with previous reports: notably, the expression of FLOWERING LOCUS C (FLC) decreased over the course of the time series while expression of LEAFY (LFY) increased. This analysis revealed a developmental time point between 10 and 12 days after germination where FLC expression had decreased but LFY expression had not yet increased, which was characterized by a peak in the number of differentially expressed genes. Gene Ontology (GO) enrichment analysis of these genes identified an overrepresentation of genes related to the cell cycle. CONCLUSIONS We discovered an unprecedented burst of differential expression of cell cycle related genes at one particular point during transition to flowering. We suggest that acceleration of rate of the divisions and partial cell cycling synchronization takes place at this point.
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Affiliation(s)
- Anna V Klepikova
- Institute for Information Transmission Problems of the Russian Academy of Sciences, Moscow, 127051, Russia.
| | - Maria D Logacheva
- Institute for Information Transmission Problems of the Russian Academy of Sciences, Moscow, 127051, Russia.
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
- Pirogov Russian National Research Medical University, 117997, Moscow, Russia.
| | - Sergey E Dmitriev
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
| | - Aleksey A Penin
- Institute for Information Transmission Problems of the Russian Academy of Sciences, Moscow, 127051, Russia.
- A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
- Department of Genetics, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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Kandasamy MK, McKinney EC, Roy E, Meagher RB. Ascomycete fungal actins differentially support plant spatial cell and organ development. Cytoskeleton (Hoboken) 2015; 72:80-92. [PMID: 25428798 DOI: 10.1002/cm.21198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 11/18/2014] [Accepted: 11/23/2014] [Indexed: 01/18/2023]
Abstract
Actin interacts with a wide variety of cytoplasmic and nuclear proteins to support spatial development in nearly all eukaryotes. Null mutations in plant vegetative actins produce dramatically altered cell, tissue, and organ morphologies. Animal cytoplasmic actins (e.g., human HsACTB, HsACTG1) and some ancestral protist actins fully suppress these mutant phenotypes suggesting that some animal, plant, and protist actins share functional competence for spatial development. Considering that fungi have a phylogenetic origin closer to animals than plants, we were interested to explore whether the fungal actins may have this same capacity to function in plants and support development. We ectopically expressed actins from four highly divergent ascomycete fungi in two different Arabidopsis double vegetative actin null mutants. We found that expression of actin from the earliest diverging ascomycete subphyla, the archiascomycete Schizosaccharomyces pombe, qualitatively and quantitatively suppressed the root cell polarity and root organ developmental defects of act8/act7 mutants and the root-hairless cell elongation phenotype of act2/act8 mutants. Interestingly, the actin from the pyrenomycete Neurospora crassa was modestly effective in the suppression of vegetative actin mutant phenotypes. In contrast, actins from the saccharomycetes Saccharomyces cerevisiae and Candida albicans were unable to support any aspect of plant development, and moreover induced severe dwarfism and sterility. These data imply that basal fungi inherited an actin with full competence for spatial development from their protist ancestor and maintained it via non-progressive sequence evolution, while the later more derived fungal species lost these activities.
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Affiliation(s)
- Muthugapatti K Kandasamy
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, Georgia; Biomedical Microscopy Core, Coverdell Center, University of Georgia, Athens, Georgia
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Liu P, Zhang H, Yu B, Xiong L, Xia Y. Proteomic identification of early salicylate- and flg22-responsive redox-sensitive proteins in Arabidopsis. Sci Rep 2015; 5:8625. [PMID: 25720653 PMCID: PMC4342551 DOI: 10.1038/srep08625] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/27/2015] [Indexed: 12/04/2022] Open
Abstract
Accumulation of reactive oxygen species (ROS) is one of the early defense responses against pathogen infection in plants. The mechanism about the initial and direct regulation of the defense signaling pathway by ROS remains elusive. Perturbation of cellular redox homeostasis by ROS is believed to alter functions of redox-sensitive proteins through their oxidative modifications. Here we report an OxiTRAQ-based proteomic study in identifying proteins whose cysteines underwent oxidative modifications in Arabidopsis cells during the early response to salicylate or flg22, two defense pathway elicitors that are known to disturb cellular redox homeostasis. Among the salicylate- and/or flg22-responsive redox-sensitive proteins are those involved in transcriptional regulation, chromatin remodeling, RNA processing, post-translational modifications, and nucleocytoplasmic shuttling. The identification of the salicylate-/flg22-responsive redox-sensitive proteins provides a foundation from which further study can be conducted toward understanding biological significance of their oxidative modifications during the plant defense response.
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Affiliation(s)
- Pei Liu
- 1] Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong [2] Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Huoming Zhang
- Biosciences Core Laboratory, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Boying Yu
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Liming Xiong
- Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Yiji Xia
- 1] Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong [2] Partner State Key Laboratory of Agrobiotechnology, Chinese University of Hong Kong, Shatin, Hong Kong
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55
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Henty-Ridilla JL, Li J, Day B, Staiger CJ. ACTIN DEPOLYMERIZING FACTOR4 regulates actin dynamics during innate immune signaling in Arabidopsis. THE PLANT CELL 2014; 26:340-52. [PMID: 24464292 PMCID: PMC3963580 DOI: 10.1105/tpc.113.122499] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 12/30/2013] [Accepted: 01/08/2014] [Indexed: 05/19/2023]
Abstract
Conserved microbe-associated molecular patterns (MAMPs) are sensed by pattern recognition receptors (PRRs) on cells of plants and animals. MAMP perception typically triggers rearrangements to actin cytoskeletal arrays during innate immune signaling. However, the signaling cascades linking PRR activation by MAMPs to cytoskeleton remodeling are not well characterized. Here, we developed a system to dissect, at high spatial and temporal resolution, the regulation of actin dynamics during innate immune signaling in plant cells. Within minutes of MAMP perception, we detected changes to single actin filament turnover in epidermal cells treated with bacterial and fungal MAMPs. These MAMP-induced alterations phenocopied an ACTIN DEPOLYMERIZING FACTOR4 (ADF4) knockout mutant. Moreover, actin arrays in the adf4 mutant were unresponsive to a bacterial MAMP, elf26, but responded normally to the fungal MAMP, chitin. Together, our data provide strong genetic and cytological evidence for the inhibition of ADF activity regulating actin remodeling during innate immune signaling. This work is the first to directly link an ADF/cofilin to the cytoskeletal rearrangements elicited directly after pathogen perception in plant or mammalian cells.
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Affiliation(s)
| | - Jiejie Li
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Brad Day
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824-6254
| | - Christopher J. Staiger
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
- The Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
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56
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Ketelaar T. The actin cytoskeleton in root hairs: all is fine at the tip. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:749-56. [PMID: 24446547 DOI: 10.1016/j.pbi.2013.10.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Filamentous actin forms characteristic bundles in plant cells that facilitate cytoplasmic streaming. In contrast, networks of actin exhibiting fast turnover are found especially near sites of rapid cell expansion. These networks may serve various functions including delivering and retaining vesicles while preventing penetration of organelles into the area where cell growth occurs thereby allowing fast turnover of vesicles to and from the plasma membrane. Root hairs elongate by polarized growth at their tips and the local accumulation of fine F-actin near the tip has provided valuable insight into the organization of these networks. Here we will sequentially focus on the role of the actin cytoskeleton in root hair tip growth and on how activities of different actin binding proteins in the apical part of growing root hairs contribute to build the fine F-actin configuration that correlates with tip growth.
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57
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Henty-Ridilla JL, Li J, Blanchoin L, Staiger CJ. Actin dynamics in the cortical array of plant cells. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:678-87. [PMID: 24246228 DOI: 10.1016/j.pbi.2013.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 05/03/2023]
Abstract
The actin cytoskeleton changes in organization and dynamics as cellular functions are reprogrammed following responses to diverse stimuli, hormones, and developmental cues. How this is choreographed and what molecular players are involved in actin remodeling continues to be an area of intense scrutiny. Advances in imaging modalities and fluorescent fusion protein reporters have illuminated the strikingly dynamic behavior of single actin filaments at high spatial and temporal resolutions. This led to a model for the stochastic dynamic turnover of actin filaments and predicted the actions and responsibilities of several key actin-binding proteins. Recently, aspects of this model have been tested using powerful genetic strategies in both Arabidopsis and Physcomitrella. Collectively, the latest data emphasize the importance of filament severing activities and regulation of barbed-end availability as key facets of plant actin filament turnover.
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58
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Cheng X, Wu Y, Guo J, Du B, Chen R, Zhu L, He G. A rice lectin receptor-like kinase that is involved in innate immune responses also contributes to seed germination. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:687-98. [PMID: 24033867 PMCID: PMC4285754 DOI: 10.1111/tpj.12328] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 08/14/2013] [Accepted: 09/05/2013] [Indexed: 05/20/2023]
Abstract
Seed germination and innate immunity both have significant effects on plant life spans because they control the plant's entry into the ecosystem and provide defenses against various external stresses, respectively. Much ecological evidence has shown that seeds with high vigor are generally more tolerant of various environmental stimuli in the field than those with low vigor. However, there is little genetic evidence linking germination and immunity in plants. Here, we show that the rice lectin receptor-like kinase OslecRK contributes to both seed germination and plant innate immunity. We demonstrate that knocking down the OslecRK gene depresses the expression of α-amylase genes, reducing seed viability and thereby decreasing the rate of seed germination. Moreover, it also inhibits the expression of defense genes, and so reduces the resistance of rice plants to fungal and bacterial pathogens as well as herbivorous insects. Yeast two-hybrid and co-immunoprecipitation experiments revealed that OslecRK interacts with an actin-depolymerizing factor (ADF) in vivo via its kinase domain. Moreover, the rice adf mutant exhibited a reduced seed germination rate due to the suppression of α-amylase gene expression. This mutant also exhibited depressed immune responses and reduced resistance to biotic stresses. Our results thus provide direct genetic evidence for a common physiological pathway connecting germination and immunity in plants. They also partially explain the common observation that high-vigor seeds often perform well in the field. The dual effects of OslecRK may be indicative of progressive adaptive evolution in rice.
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Affiliation(s)
- Xiaoyan Cheng
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
| | - Yan Wu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
| | - Jianping Guo
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
| | - Bo Du
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
| | - Rongzhi Chen
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
| | - Lili Zhu
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
| | - Guangcun He
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan UniversityWuhan, 430072, China
- For correspondence (e-mail )
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59
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Dong CH, Hong Y. Arabidopsis CDPK6 phosphorylates ADF1 at N-terminal serine 6 predominantly. PLANT CELL REPORTS 2013; 32:1715-28. [PMID: 23903947 DOI: 10.1007/s00299-013-1482-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 06/26/2013] [Accepted: 07/15/2013] [Indexed: 05/20/2023]
Abstract
KEY MESSAGE We found that Arabidopsis AtADF1 was phosphorylated by AtCDPK6 at serine 6 predominantly and the phosphoregulation plays a key role in the regulation of ADF1-mediated depolymerization of actin filaments. ABSTRACT Since actin-depolymerizing factor (ADF) is highly conserved among eukaryotes, it is one of the key modulators for actin organization. In plants, ADF is directly involved in the depolymerization of actin filaments, and therefore important for F-actin-dependent cellular activities. The activity of ADF is tightly controlled through a number of molecular mechanisms, including phosphorylation-mediated inactivation of ADF. To investigate Arabidopsis ADF1 phosphoregulation, we generated AtADF1 phosphorylation site-specific mutants. Using transient expression and stable transgenic approaches, we analyzed the ADF1 phosphorylation mutants in the regulation of actin filament organizations in plant cells. By in vitro phosphorylation assay, we showed that AtADF1 is phosphorylated by AtCDPK6 at serine 6 predominantly. Chemically induced expression of AtCDPK6 can negatively regulate the wild-type AtADF1 in depolymerizing actin filaments, but not those of the mutants AtADF1(S6A) and AtADF1(S6D). These results demonstrate a regulatory function of Arabidopsis CDPK6 in the N-terminal phosphorylation of AtADF1.
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Affiliation(s)
- Chun-Hai Dong
- College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, People's Republic of China,
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60
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Khandakar J, Haraguchi I, Yamaguchi K, Kitamura Y. A small-scale proteomic approach reveals a survival strategy, including a reduction in alkaloid biosynthesis, in Hyoscyamus albus roots subjected to iron deficiency. FRONTIERS IN PLANT SCIENCE 2013; 4:331. [PMID: 24009619 PMCID: PMC3755260 DOI: 10.3389/fpls.2013.00331] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/06/2013] [Indexed: 05/22/2023]
Abstract
Hyoscyamus albus is a well-known source of the tropane alkaloids, hyoscyamine and scopolamine, which are biosynthesized in the roots. To assess the major biochemical adaptations that occur in the roots of this plant in response to iron deficiency, we used a small-scale proteomic approach in which 100 mg of root tips were treated with and without Fe, respectively, for 5 days. Two-dimensional mini gels showed that 48 spots were differentially accumulated between the two conditions of Fe availability and a further 36 proteins were identified from these spots using MALDI-QIT-TOF mass spectrometry. The proteins that showed elevated levels in the roots lacking Fe were found to be associated variously with carbohydrate metabolism, cell differentiation, secondary metabolism, and oxidative defense. Most of the proteins involved in carbohydrate metabolism were increased in abundance, but mitochondrial NAD-dependent malate dehydrogenase was decreased, possibly resulting in malate secretion. Otherwise, all the proteins showing diminished levels in the roots were identified as either Fe-containing or ATP-requiring. For example, a significant decrease was observed in the levels of hyoscyamine 6β-hydroxylase (H6H), which requires Fe and is involved in the conversion of hyoscyamine to scopolamine. To investigate the effects of Fe deficiency on alkaloid biosynthesis, gene expression studies were undertaken both for H6H and for another Fe-dependent protein, Cyp80F1, which is involved in the final stage of hyoscyamine biosynthesis. In addition, tropane alkaloid contents were determined. Reduced gene expression was observed in the case of both of these proteins and was accompanied by a decrease in the content of both hyoscyamine and scopolamine. Finally, we have discussed energetic and Fe-conservation strategies that might be adopted by the roots of H. albus to maintain iron homeostasis under Fe-limiting conditions.
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Affiliation(s)
| | - Izumi Haraguchi
- Graduate School of Fisheries Science and Environmental Studies, Nagasaki UniversityNagasaki, Japan
| | - Kenichi Yamaguchi
- Graduate School of Science and Technology, Nagasaki UniversityNagasaki, Japan
- Graduate School of Fisheries Science and Environmental Studies, Nagasaki UniversityNagasaki, Japan
- Division of Biochemistry, Faculty of Fisheries, Nagasaki UniversityNagasaki, Japan
| | - Yoshie Kitamura
- Graduate School of Science and Technology, Nagasaki UniversityNagasaki, Japan
- Graduate School of Fisheries Science and Environmental Studies, Nagasaki UniversityNagasaki, Japan
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61
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Wang M, Yuan D, Gao W, Li Y, Tan J, Zhang X. A comparative genome analysis of PME and PMEI families reveals the evolution of pectin metabolism in plant cell walls. PLoS One 2013; 8:e72082. [PMID: 23951288 PMCID: PMC3741192 DOI: 10.1371/journal.pone.0072082] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 07/04/2013] [Indexed: 12/13/2022] Open
Abstract
Pectins are fundamental polysaccharides in the plant primary cell wall. Pectins are synthesized and secreted to cell walls as highly methyl-esterified polymers and then demethyl-esterified by pectin methylesterases (PMEs), which are spatially regulated by pectin methylesterase inhibitors (PMEIs). Although PME and PMEI genes are pivotal in plant cell wall formation, few studies have focused on the evolutionary patterns of the PME and PMEI gene families. In this study, the gene origin, evolution, and expression diversity of these two families were systematically analyzed using 11 representative species, including algae, bryophytes, lycophytes and flowering land plants. The results show that 1) for the two subfamilies (PME and proPME) of PME, the origin of the PME subfamily is consistent with the appearance of pectins in early charophyte cell walls, 2) Whole genome duplication (WGD) and tandem duplication contribute to the expansion of proPME and PMEI families in land plants, 3) Evidence of selection pressure shows that the proPME and PMEI families have rapidly evolved, particularly the PMEI family in vascular plants, and 4) Comparative expression profile analysis of the two families indicates that the eudicot Arabidopsis and monocot rice have different expression patterns. In addition, the gene structure and sequence analyses show that the origin of the PMEI domain may be derived from the neofunctionalization of the pro domain after WGD. This study will advance the evolutionary understanding of the PME and PMEI families and plant cell wall development.
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Affiliation(s)
- Maojun Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Daojun Yuan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Wenhui Gao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yang Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Jiafu Tan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xianlong Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China
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Wang R, Gao F, Guo BQ, Huang JC, Wang L, Zhou YJ. Short-term chromium-stress-induced alterations in the maize leaf proteome. Int J Mol Sci 2013; 14:11125-44. [PMID: 23712354 PMCID: PMC3709723 DOI: 10.3390/ijms140611125] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 04/25/2013] [Accepted: 05/15/2013] [Indexed: 11/16/2022] Open
Abstract
Soil contamination by chromium (Cr) has become an increasing problem worldwide as a result of extensive industrial activities. Chromium, especially hexavalent Cr, impairs the growth and productivity of plants. Although it has been proposed that plants could modify their metabolism to adapt to Cr stress by reprogramming the expression of genes, especially those related to the antioxidant system, damage response, and electron transport chain, evidence at the protein expression level is lacking. To better understand the precise mechanisms underlying Cr phytoxicity and the plant response to Cr exposure, the time-course of changes in the protein expression profile induced by short-term hexavalent Cr exposure (1, 6 and 24 h) were analyzed in maize leaves. Among the over 1200 protein spots detected reproducibly by two-dimensional electrophoresis (2-DE), 60 were found to be differentially accumulated during Cr stress treatment. Of the Cr-regulated proteins, 58 were identified using tandem mass spectrometry (MS/MS). The Cr-regulated proteins identified were mainly involved in ROS detoxification and defense responses (26%), photosynthesis and chloroplast organization (22%), post-transcriptional processing of mRNA and rRNA (12%), protein synthesis and folding (10%), the DNA damage response (5%), and the cytoskeleton (3%). The possible involvement of these Cr stress-responsive proteins in Cr phytoxicity and the plant response to Cr exposure in maize is discussed, taking into consideration the information available from other plant models. Our results provide preliminary evidence that will facilitate understanding the molecular mechanisms underlying Cr toxicity in maize.
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Affiliation(s)
- Rong Wang
- College of Life Science, Fuyang Teachers College, Fuyang 236037, China; E-Mails: (R.W.); (J.-C.H.)
| | - Fei Gao
- College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China; E-Mails: (F.G.); (B.-Q.G.)
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Bing-Qian Guo
- College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China; E-Mails: (F.G.); (B.-Q.G.)
| | - Ji-Chang Huang
- College of Life Science, Fuyang Teachers College, Fuyang 236037, China; E-Mails: (R.W.); (J.-C.H.)
| | - Lei Wang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
- Authors to whom correspondence should be addressed; E-Mails: (L.W.); (Y.-J.Z.); Tel./Fax: +86-10-8210-6134 (L.W.); +86-10-6893-2922 (Y.-J.Z.)
| | - Yi-Jun Zhou
- College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China; E-Mails: (F.G.); (B.-Q.G.)
- Authors to whom correspondence should be addressed; E-Mails: (L.W.); (Y.-J.Z.); Tel./Fax: +86-10-8210-6134 (L.W.); +86-10-6893-2922 (Y.-J.Z.)
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63
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Porter K, Day B. Actin branches out to link pathogen perception and host gene regulation. PLANT SIGNALING & BEHAVIOR 2013; 8:e23468. [PMID: 23333960 PMCID: PMC3676516 DOI: 10.4161/psb.23468] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 12/30/2012] [Indexed: 05/29/2023]
Abstract
Cellular functions of actin, and associated actin binding proteins (ABPs), have been well characterized with respect to their dynamic cytosolic role as components of the complex cytoskeletal network. In this regard, the collective research in this field has vastly expanded our knowledge of the role of actin to more recently identify a key role within the nucleus as an integral part gene organization and expression. Herein, we describe the requirement of the ABP actin depolymerizing factor-4 (ADF4) as a regulator of resistance to Pseudomonas syringae DC3000 expressing the effector AvrPphB via ADF4's cytosolic and nuclear functions. In total, our work has identified significant alterations in the expression of the resistance protein RPS5 in an ADF4 phosphorylation dependent manner. In this mini-review, we provide compelling evidence in support of both a nuclear function for ADF4, as well as potential targeting of the actin cytoskeleton by the bacterial effector AvrPphB.
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Affiliation(s)
- Katie Porter
- Graduate Program in Cell and Molecular Biology; Michigan State University; East Lansing, MI USA
| | - Brad Day
- Graduate Program in Cell and Molecular Biology; Michigan State University; East Lansing, MI USA
- Department of Plant, Soil, and Microbial Sciences; Michigan State University; East Lansing, MI USA
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An Arabidopsis tissue-specific RNAi method for studying genes essential to mitosis. PLoS One 2012; 7:e51388. [PMID: 23236491 PMCID: PMC3517552 DOI: 10.1371/journal.pone.0051388] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 11/02/2012] [Indexed: 11/19/2022] Open
Abstract
A large fraction of the genes in plants can be considered essential in the sense that when absent the plant fails to develop past the first few cell divisions. The fact that angiosperms pass through a haploid gametophyte stage can make it challenging to propagate such mutants even in the heterozygous condition. Here we describe a tissue-specific RNAi method that allows us to visualize cell division phenotypes in petals, which are large dispensable organs. Portions of the APETALA (AP3) and PISTILLATA (PI) promoters confer early petal-specific expression. We show that when either promoter is used to drive the expression of a beta-glucuronidase (GUS) RNAi transgene in plants uniformly expressing GUS, GUS expression is knocked down specifically in petals. We further tested the system by targeting the essential kinetochore protein CENPC and two different components of the Spindle Assembly Checkpoint (MAD2 and BUBR1). Plant lines expressing petal-specific RNAi hairpins targeting these genes exhibited an array of petal phenotypes. Cytological analyses of the affected flower buds confirmed that CENPC knockdown causes cell cycle arrest but provided no evidence that either MAD2 or BUBR1 are required for mitosis (although both genes are required for petal growth by this assay). A key benefit of the petal-specific RNAi method is that the phenotypes are not expressed in the lineages leading to germ cells, and the phenotypes are faithfully transmitted for at least four generations despite their pronounced effects on growth.
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65
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Huang YC, Huang WL, Hong CY, Lur HS, Chang MC. Comprehensive analysis of differentially expressed rice actin depolymerizing factor gene family and heterologous overexpression of OsADF3 confers Arabidopsis Thaliana drought tolerance. RICE (NEW YORK, N.Y.) 2012; 5:33. [PMID: 24279948 PMCID: PMC4883719 DOI: 10.1186/1939-8433-5-33] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 11/21/2012] [Indexed: 05/04/2023]
Abstract
BACKGROUND Actin depolymerizing factors (ADFs) are small actin-binding proteins. Many higher-plant ADFs has been known to involve in plant growth, development and pathogen defense. However, in rice the temporal and spatial expression of OsADF gene family and their relationship with abiotic stresses tolerance is still unknown. RESULTS Here we reported the first comprehensive gene expression profile analysis of OsADF gene family. The OsADF genes showed distinct and overlapping gene expression patterns at different growth stages, tissues and abiotic stresses. We also demonstrated that both OsADF1 and OsADF3 proteins were localized in the nucleus. OsADF1 and OsADF3 were preferentially expressed in vascular tissues. Under ABA or abiotic stress treatments, OsADF3::GUS activity was enhanced in lateral roots and root tips. Ectopically overexpressed OsADF3 conferred the mannitol- and drought-stress tolerance of transgenic Arabidopsis seedlings by increasing germination rate, primary root length and survival. Several drought-tolerance responsive genes (RD22, ABF4, DREB2A, RD29A, PIP1; 4 and PIP2; 6) were upregulated in transgenic Arabidopsis under drought stress. CONCLUSIONS These results suggested that OsADF gene family may participate in plant abiotic stresses response or tolerance and would facilitate functional validation of other OsADF genes.
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Affiliation(s)
- Ya-Chen Huang
- />Department of Agronomy, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 106 Taiwan Republic of China
| | - Wen-Lii Huang
- />Department of Agronomy, National Chiayi University, No.300 Syuefu Rd., Chiayi, 60004 Taiwan Republic of China
| | - Chwan-Yang Hong
- />Department of Agriculture Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 106 Taiwan Republic of China
| | - Hur-Shen Lur
- />Department of Agronomy, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 106 Taiwan Republic of China
| | - Men-Chi Chang
- />Department of Agronomy, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 106 Taiwan Republic of China
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Thomas C. Bundling actin filaments from membranes: some novel players. FRONTIERS IN PLANT SCIENCE 2012; 3:188. [PMID: 22936939 PMCID: PMC3426786 DOI: 10.3389/fpls.2012.00188] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 08/01/2012] [Indexed: 05/04/2023]
Abstract
Progress in live-cell imaging of the cytoskeleton has significantly extended our knowledge about the organization and dynamics of actin filaments near the plasma membrane of plant cells. Noticeably, two populations of filamentous structures can be distinguished. On the one hand, fine actin filaments which exhibit an extremely dynamic behavior basically characterized by fast polymerization and prolific severing events, a process referred to as actin stochastic dynamics. On the other hand, thick actin bundles which are composed of several filaments and which are comparatively more stable although they constantly remodel as well. There is evidence that the actin cytoskeleton plays critical roles in trafficking and signaling at both the cell cortex and organelle periphery but the exact contribution of actin bundles remains unclear. A common view is that actin bundles provide the long-distance tracks used by myosin motors to deliver their cargo to growing regions and accordingly play a particularly important role in cell polarization. However, several studies support that actin bundles are more than simple passive highways and display multiple and dynamic roles in the regulation of many processes, such as cell elongation, polar auxin transport, stomatal and chloroplast movement, and defense against pathogens. The list of identified plant actin-bundling proteins is ever expanding, supporting that plant cells shape structurally and functionally different actin bundles. Here I review the most recently characterized actin-bundling proteins, with a particular focus on those potentially relevant to membrane trafficking and/or signaling.
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Affiliation(s)
- Clément Thomas
- Laboratory of Molecular and Cellular Oncology, Department of Oncology, Public Research Centre for Health (CRP-Santé)Luxembourg, Luxembourg
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Wen F, Wang J, Xing D. A protein phosphatase 2A catalytic subunit modulates blue light-induced chloroplast avoidance movements through regulating actin cytoskeleton in Arabidopsis. PLANT & CELL PHYSIOLOGY 2012; 53:1366-1379. [PMID: 22642987 DOI: 10.1093/pcp/pcs081] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Chloroplast avoidance movements mediated by phototropin 2 (phot2) are one of most important physiological events in the response to high-fluence blue light (BL), which reduces damage to the photosynthetic machinery under excess light. Protein phosphatase 2A-2 (PP2A-2) is an isoform of the catalytic subunit of PP2A, which regulates a number of developmental processes. To investigate whether PP2A-2 was involved in high-fluence BL-induced chloroplast avoidance movements, we first analyzed chloroplast migration in the leaves of the pp2a-2 mutant in response to BL. The data showed that PP2A-2 might act as a positive regulator in phot2-mediated chloroplast avoidance movements, but not in phot1-mediated chloroplast accumulation movements. Then, the effect of okadaic acid (OA) and cantharidin (selective PP2A inhibitors) on high-fluence BL response was further investigated in Arabidopsis thaliana mesophyll cells. Within a certain concentration range, exogenously applied OA or cantharidin inhibited the high-fluence BL-induced chloroplast movements in a concentration-dependent manner. Actin depolymerizing factor (ADF)/cofilin phosphorylation assays demonstrated that PP2A-2 can activate/dephosphorylate ADF/cofilin, an actin-binding protein, in Arabidopsis mesophyll cells. Consistent with this observation, the experiments showed that OA could inhibit ADF1 binding to the actin and suppress the reorganization of the actin cytoskeleton after high-fluence BL irradiation. The adf1 and adf3 mutants also exhibited reduced high-fluence BL-induced chloroplast avoidance movements. In conclusion, we identified that PP2A-2 regulated the activation of ADF/cofilin, which, in turn, regulated actin cytoskeleton remodeling and was involved in phot2-mediated chloroplast avoidance movements.
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Affiliation(s)
- Feng Wen
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, China
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68
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Neelakandan AK, Wang K. Recent progress in the understanding of tissue culture-induced genome level changes in plants and potential applications. PLANT CELL REPORTS 2012; 31:597-620. [PMID: 22179259 DOI: 10.1007/s00299-011-1202-z] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 11/30/2011] [Accepted: 12/01/2011] [Indexed: 05/23/2023]
Abstract
In vitro cell and tissue-based systems have tremendous potential in fundamental research and for commercial applications such as clonal propagation, genetic engineering and production of valuable metabolites. Since the invention of plant cell and tissue culture techniques more than half a century ago, scientists have been trying to understand the morphological, physiological, biochemical and molecular changes associated with tissue culture responses. Establishment of de novo developmental cell fate in vitro is governed by factors such as genetic make-up, stress and plant growth regulators. In vitro culture is believed to destabilize the genetic and epigenetic program of intact plant tissue and can lead to chromosomal and DNA sequence variations, methylation changes, transposon activation, and generation of somaclonal variants. In this review, we discuss the current status of understanding the genomic and epigenomic changes that take place under in vitro conditions. It is hoped that a precise and comprehensive knowledge of the molecular basis of these variations and acquisition of developmental cell fate would help to devise strategies to improve the totipotency and embryogenic capability in recalcitrant species and genotypes, and to address bottlenecks associated with clonal propagation.
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Huang YF, Doligez A, Fournier-Level A, Le Cunff L, Bertrand Y, Canaguier A, Morel C, Miralles V, Veran F, Souquet JM, Cheynier V, Terrier N, This P. Dissecting genetic architecture of grape proanthocyanidin composition through quantitative trait locus mapping. BMC PLANT BIOLOGY 2012; 12:30. [PMID: 22369244 PMCID: PMC3312867 DOI: 10.1186/1471-2229-12-30] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 02/27/2012] [Indexed: 05/20/2023]
Abstract
BACKGROUND Proanthocyanidins (PAs), or condensed tannins, are flavonoid polymers, widespread throughout the plant kingdom, which provide protection against herbivores while conferring organoleptic and nutritive values to plant-derived foods, such as wine. However, the genetic basis of qualitative and quantitative PA composition variation is still poorly understood. To elucidate the genetic architecture of the complex grape PA composition, we first carried out quantitative trait locus (QTL) analysis on a 191-individual pseudo-F1 progeny. Three categories of PA variables were assessed: total content, percentages of constitutive subunits and composite ratio variables. For nine functional candidate genes, among which eight co-located with QTLs, we performed association analyses using a diversity panel of 141 grapevine cultivars in order to identify causal SNPs. RESULTS Multiple QTL analysis revealed a total of 103 and 43 QTLs, respectively for seed and skin PA variables. Loci were mainly of additive effect while some loci were primarily of dominant effect. Results also showed a large involvement of pairwise epistatic interactions in shaping PA composition. QTLs for PA variables in skin and seeds differed in number, position, involvement of epistatic interaction and allelic effect, thus revealing different genetic determinisms for grape PA composition in seeds and skin. Association results were consistent with QTL analyses in most cases: four out of nine tested candidate genes (VvLAR1, VvMYBPA2, VvCHI1, VvMYBPA1) showed at least one significant association with PA variables, especially VvLAR1 revealed as of great interest for further functional investigation. Some SNP-phenotype associations were observed only in the diversity panel. CONCLUSIONS This study presents the first QTL analysis on grape berry PA composition with a comparison between skin and seeds, together with an association study. Our results suggest a complex genetic control for PA traits and different genetic architectures for grape PA composition between berry skin and seeds. This work also uncovers novel genomic regions for further investigation in order to increase our knowledge of the genetic basis of PA composition.
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Affiliation(s)
- Yung-Fen Huang
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
- INRA, UMR1083 SPO, 2, place, Viala, 34060 Montpellier, France
| | - Agnès Doligez
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
| | - Alexandre Fournier-Level
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, Box G-W, Providence, RI 02912, USA
| | - Loïc Le Cunff
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
- UMT Geno-Vigne®, IFV, 2, place Viala, 34060 Montpellier, France
| | - Yves Bertrand
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
| | - Aurélie Canaguier
- UMR Génomique Végétale, INRA UEVE ERL CNRS, 2, rue Gaston Crémieux, 91057 Evry, France
| | - Cécile Morel
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
| | | | - Frédéric Veran
- INRA, UMR1083 SPO, 2, place, Viala, 34060 Montpellier, France
| | | | | | - Nancy Terrier
- INRA, UMR1083 SPO, 2, place, Viala, 34060 Montpellier, France
| | - Patrice This
- UMR AGAP, INRA, 2, place Viala, 34060 Montpellier, France
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Augustine RC, Pattavina KA, Tüzel E, Vidali L, Bezanilla M. Actin interacting protein1 and actin depolymerizing factor drive rapid actin dynamics in Physcomitrella patens. THE PLANT CELL 2011; 23:3696-710. [PMID: 22003077 PMCID: PMC3229144 DOI: 10.1105/tpc.111.090753] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The remodeling of actin networks is required for a variety of cellular processes in eukaryotes. In plants, several actin binding proteins have been implicated in remodeling cortical actin filaments (F-actin). However, the extent to which these proteins support F-actin dynamics in planta has not been tested. Using reverse genetics, complementation analyses, and cell biological approaches, we assessed the in vivo function of two actin turnover proteins: actin interacting protein1 (AIP1) and actin depolymerizing factor (ADF). We report that AIP1 is a single-copy gene in the moss Physcomitrella patens. AIP1 knockout plants are viable but have reduced expansion of tip-growing cells. AIP1 is diffusely cytosolic and functions in a common genetic pathway with ADF to promote tip growth. Specifically, ADF can partially compensate for loss of AIP1, and AIP1 requires ADF for function. Consistent with a role in actin remodeling, AIP1 knockout lines accumulate F-actin bundles, have fewer dynamic ends, and have reduced severing frequency. Importantly, we demonstrate that AIP1 promotes and ADF is essential for cortical F-actin dynamics.
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Affiliation(s)
- Robert C. Augustine
- Biology Department, University of Massachusetts, Amherst, Massachusetts 01003
| | - Kelli A. Pattavina
- Biology Department, University of Massachusetts, Amherst, Massachusetts 01003
| | - Erkan Tüzel
- Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts 01609
| | - Magdalena Bezanilla
- Biology Department, University of Massachusetts, Amherst, Massachusetts 01003
- Address correspondence to
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Lo YS, Cheng N, Hsiao LJ, Annamalai A, Jauh GY, Wen TN, Dai H, Chiang KS. Actin in Mung Bean Mitochondria and Implications for Its Function. THE PLANT CELL 2011; 23:3727-44. [PMID: 21984697 PMCID: PMC3229146 DOI: 10.1105/tpc.111.087403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Abstract
Here, a large fraction of plant mitochondrial actin was found to be resistant to protease and high-salt treatments, suggesting it was protected by mitochondrial membranes. A portion of this actin became sensitive to protease or high-salt treatment after removal of the mitochondrial outer membrane, indicating that some actin is located inside the mitochondrial outer membrane. The import of an actin–green fluorescent protein (GFP) fusion protein into the mitochondria in a transgenic plant, actin:GFP, was visualized in living cells and demonstrated by flow cytometry and immunoblot analyses. Polymerized actin was found in mitochondria of actin:GFP plants and in mung bean (Vigna radiata). Notably, actin associated with mitochondria purified from early-developing cotyledons during seed germination was sensitive to high-salt and protease treatments. With cotyledon ageing, mitochondrial actin became more resistant to both treatments. The progressive import of actin into cotyledon mitochondria appeared to occur in concert with the conversion of quiescent mitochondria into active forms during seed germination. The binding of actin to mitochondrial DNA (mtDNA) was demonstrated by liquid chromatography–tandem mass spectrometry analysis. Porin and ADP/ATP carrier proteins were also found in mtDNA-protein complexes. Treatment with an actin depolymerization reagent reduced the mitochondrial membrane potential and triggered the release of cytochrome C. The potential function of mitochondrial actin and a possible actin import pathway are discussed.
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Affiliation(s)
- Yih-Shan Lo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Ning Cheng
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Lin-June Hsiao
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Arunachalam Annamalai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Guang-Yuh Jauh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Tuan-Nan Wen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Hwa Dai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China
| | - Kwen-Sheng Chiang
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637
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Henty JL, Bledsoe SW, Khurana P, Meagher RB, Day B, Blanchoin L, Staiger CJ. Arabidopsis actin depolymerizing factor4 modulates the stochastic dynamic behavior of actin filaments in the cortical array of epidermal cells. THE PLANT CELL 2011; 23:3711-26. [PMID: 22010035 PMCID: PMC3229145 DOI: 10.1105/tpc.111.090670] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 09/27/2011] [Accepted: 10/06/2011] [Indexed: 05/19/2023]
Abstract
Actin filament arrays are constantly remodeled as the needs of cells change as well as during responses to biotic and abiotic stimuli. Previous studies demonstrate that many single actin filaments in the cortical array of living Arabidopsis thaliana epidermal cells undergo stochastic dynamics, a combination of rapid growth balanced by disassembly from prolific severing activity. Filament turnover and dynamics are well understood from in vitro biochemical analyses and simple reconstituted systems. However, the identification in living cells of the molecular players involved in controlling actin dynamics awaits the use of model systems, especially ones where the power of genetics can be combined with imaging of individual actin filaments at high spatial and temporal resolution. Here, we test the hypothesis that actin depolymerizing factor (ADF)/cofilin contributes to stochastic filament severing and facilitates actin turnover. A knockout mutant for Arabidopsis ADF4 has longer hypocotyls and epidermal cells when compared with wild-type seedlings. This correlates with a change in actin filament architecture; cytoskeletal arrays in adf4 cells are significantly more bundled and less dense than in wild-type cells. Several parameters of single actin filament turnover are also altered. Notably, adf4 mutant cells have a 2.5-fold reduced severing frequency as well as significantly increased actin filament lengths and lifetimes. Thus, we provide evidence that ADF4 contributes to the stochastic dynamic turnover of actin filaments in plant cells.
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Affiliation(s)
- Jessica L. Henty
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Samuel W. Bledsoe
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Parul Khurana
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
- School of Natural Science and Mathematics, Indiana University East, Richmond, Indiana 47374
| | - Richard B. Meagher
- Department of Genetics, University of Georgia, Athens, Georgia 30602-7223
| | - Brad Day
- Department of Plant Pathology, Michigan State University, East Lansing, Michigan 48824-1311
| | - Laurent Blanchoin
- Institut de Recherches en Technologie et Sciences pour le Vivant, Laboratoire de Physiologie Cellulaire and Végétale, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Universite Joseph Fourier, F38054 Grenoble, France
| | - Christopher J. Staiger
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
- The Bindley Bioscience Center, Discovery Park, Purdue University, West Lafayette, Indiana 47907
- Address correspondence to
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Bou Daher F, van Oostende C, Geitmann A. Spatial and temporal expression of actin depolymerizing factors ADF7 and ADF10 during male gametophyte development in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2011; 52:1177-92. [PMID: 21632657 DOI: 10.1093/pcp/pcr068] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The actin cytoskeleton plays a crucial role in many aspects of plant cell development. During male gametophyte development, the actin arrays are conspicuously remodeled both during pollen maturation in the anther and after pollen hydration on the receptive stigma and pollen tube elongation. Remodeling of actin arrays results from the highly orchestrated activities of numerous actin binding proteins (ABPs). A key player in actin remodeling is the actin depolymerizing factor (ADF), which increases actin filament treadmilling rates. We prepared fluorescent protein fusions of two Arabidopsis pollen-specific ADFs, ADF7 and ADF10. We monitored the expression and subcellular localization of these proteins during male gametophyte development, pollen germination and pollen tube growth. ADF7 and ADF10 were differentially expressed with the ADF7 signal appearing in the microspore stage and that of ADF10 only during the polarized microspore stage. ADF7 was associated with the microspore nucleus and the vegetative nucleus of the mature grain during less metabolically active stages, but in germinating pollen grains and elongating pollen tubes, it was associated with the subapical actin fringe. On the other hand, ADF10 was associated with filamentous actin in the developing gametophyte, in particular with the arrays surrounding the apertures of the mature pollen grain. In the shank of elongating pollen tubes, ADF10 was associated with thick actin cables. We propose possible specific functions of these two ADFs based on their differences in expression and localization.
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Affiliation(s)
- Firas Bou Daher
- Université de Montréal, Département de sciences biologiques, Institut de Recherche en Biologie Végétale, 4101 Sherbrooke East, Montreal, Quebec, Canada
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Tholl S, Moreau F, Hoffmann C, Arumugam K, Dieterle M, Moes D, Neumann K, Steinmetz A, Thomas C. Arabidopsis actin-depolymerizing factors (ADFs) 1 and 9 display antagonist activities. FEBS Lett 2011; 585:1821-7. [PMID: 21570971 DOI: 10.1016/j.febslet.2011.05.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 01/05/2023]
Abstract
We provide evidence that one of the 11 Arabidopsis actin-depolymerizing factors (ADFs), namely ADF9, does not display typical F-actin depolymerizing activity. Instead, ADF9 effectively stabilizes actin filaments in vitro and concomitantly bundles actin filaments with the highest efficiency under acidic conditions. Competition experiments show that ADF9 antagonizes ADF1 activity by reducing its ability to potentiate F-actin depolymerization. Accordingly, ectopic expression of ADF1 and ADF9 in tobacco cells has opposite effects. ADF1 severs actin filaments/bundles and promotes actin cytoskeleton disassembly, whereas ADF9 induces the formation of long bundles. Together these data reveal an additional degree of complexity in the comprehension of the biological functions of the ADF family and illustrate that antagonist activities can be displayed by seemingly equivalent actin-binding proteins.
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Affiliation(s)
- Stéphane Tholl
- Centre de Recherche Public-Santé, Luxembourg, Luxembourg
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Abstract
BACKGROUND INFORMATION Although actin is a relevant component of the plant nucleus, only three nuclear ABPs (actin-binding proteins) have been identified in plants to date: cofilin, profilin and nuclear myosin I. Although plants lack orthologues of the main structural nuclear ABPs in animals, such as lamins, lamin-associated proteins and nesprins, their genome does contain sequences with spectrin repeats and N-terminal calponin homology domains for actin binding that might be distant relatives of spectrin. We investigated here whether spectrin-like proteins could act as structural nuclear ABPs in plants. RESULTS We have investigated the presence of spectrins in Allium cepa meristematic nuclei by Western blotting, confocal and electron microscopy, using antibodies against α- and β-spectrin chains that cross-react in plant nuclei. Their role as nuclear ABPs was analysed by co-immunoprecipitation and IF (immunofluorescence) co-localization and their association with the nuclear matrix was investigated by sequential extraction of nuclei with non-ionic detergent, and in low- and high-salt buffers after nuclease digestion. Our results demonstrate the existence of several spectrin-like proteins in the nucleus of onion cells that have different intranuclear distributions in asynchronous meristematic populations and associate with the nuclear matrix. These nuclear proteins co-immunoprecipitate and co-localize with actin. CONCLUSIONS These results reveal that the plant nucleus contains spectrin-like proteins that are structural nuclear components and function as ABPs. Their intranuclear distribution suggests that plant nuclear spectrin-like proteins could be involved in multiple nuclear functions.
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Lan P, Li W, Wen TN, Shiau JY, Wu YC, Lin W, Schmidt W. iTRAQ protein profile analysis of Arabidopsis roots reveals new aspects critical for iron homeostasis. PLANT PHYSIOLOGY 2011; 155:821-34. [PMID: 21173025 PMCID: PMC3032469 DOI: 10.1104/pp.110.169508] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 12/15/2010] [Indexed: 05/17/2023]
Abstract
Iron (Fe) deficiency is a major constraint for plant growth and affects the quality of edible plant parts. To investigate the mechanisms underlying Fe homeostasis in plants, Fe deficiency-induced changes in the protein profile of Arabidopsis (Arabidopsis thaliana) roots were comprehensively analyzed using iTRAQ (Isobaric Tag for Relative and Absolute Quantification) differential liquid chromatography-tandem mass spectrometry on a LTQ-Orbitrap with high-energy collision dissociation. A total of 4,454 proteins were identified with a false discovery rate of less than 1.1%, and 2,882 were reliably quantified. A subset of 101 proteins was differentially expressed upon Fe deficiency. The changes in protein profiles upon Fe deficiency show low congruency with previously reported alterations in transcript levels, indicating posttranscriptional changes, and provide complementary information on Fe deficiency-induced processes. The abundance of proteins involved in the synthesis/regeneration of S-adenosylmethionine, the phenylpropanoid pathway, the response to oxidative stress, and respiration was highly increased by Fe deficiency. Using Fe-responsive proteins as bait, genome-wide fishing for partners with predictable or confirmed interologs revealed that RNA processing and ribonucleoprotein complex assembly may represent critical processes that contribute to the regulation of root responses to Fe deficiency, possibly by biasing translation efficiency.
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78
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Kandasamy MK, McKinney EC, Meagher RB. Differential sublocalization of actin variants within the nucleus. Cytoskeleton (Hoboken) 2011; 67:729-43. [PMID: 20862689 DOI: 10.1002/cm.20484] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Conventional actin has been implicated in various nuclear processes including chromatin remodeling, transcription, nuclear transport, and overall nuclear structure. Moreover, actin has been identified as a component of several chromatin remodeling complexes present in the nucleus. In animal cells, nuclear actin exists as a dynamic equilibrium of monomers and polymers. Actin-binding proteins (ABPs) such as ADF/cofilin and profilin play a role in actin import and export, respectively. However, very little is known about the localization and roles of nuclear actin in plants. In multicellular plants and animals, actin is comprised of an ancient and divergent family of protein variants. Here, we have investigated the presence and differential localization of two ancient subclasses of actin in isolated Arabidopsis nuclei. Although the subclass 1 variants ACT2 and ACT8 and subclass 2 variant ACT7 were found distributed throughout the nucleoplasm, ACT7 was often found more concentrated in nuclear speckles than subclass 1 variants. The nuclei from the act2-1/act8-2 double null mutant and the act7-5 null mutant lacked their corresponding actin variants. In addition, serial sectioning of several independent nuclei revealed that ACT7 was notably more abundant in the nucleolus than the subclass 1 actins. Profilin and ADF proteins were also found in significant levels in plant nuclei. The possible functions of differentially localized nuclear actin variants are discussed.
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Affiliation(s)
- Muthugapatti K Kandasamy
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, Georgia 30602, USA
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80
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Deal RB, Henikoff S. The INTACT method for cell type-specific gene expression and chromatin profiling in Arabidopsis thaliana. Nat Protoc 2010; 6:56-68. [PMID: 21212783 DOI: 10.1038/nprot.2010.175] [Citation(s) in RCA: 291] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genomic studies of cell differentiation and function within a whole organism depend on the ability to isolate specific cell types from a tissue, but this is technically difficult. We developed a method called INTACT (isolation of nuclei tagged in specific cell types) that allows affinity-based isolation of nuclei from individual cell types of a tissue, thereby circumventing the problems associated with mechanical purification techniques. In this method nuclei are affinity-labeled through transgenic expression of a biotinylated nuclear envelope protein in the cell type of interest. Total nuclei are isolated from transgenic plants and biotin-labeled nuclei are then purified using streptavidin-coated magnetic beads, without the need for specialized equipment. INTACT gives high yield and purity of nuclei from the desired cell types, which can be used for genome-wide analysis of gene expression and chromatin features. The entire procedure, from nuclei purification through cDNA preparation or chromatin immunoprecipitation (ChIP), can be completed within 2 d. The protocol we present assumes that transgenic lines are already available, and includes procedural details for amplification of cDNA or ChIP DNA prior to microarray or deep sequencing analysis.
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Affiliation(s)
- Roger B Deal
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
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81
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Papuga J, Hoffmann C, Dieterle M, Moes D, Moreau F, Tholl S, Steinmetz A, Thomas C. Arabidopsis LIM proteins: a family of actin bundlers with distinct expression patterns and modes of regulation. THE PLANT CELL 2010; 22:3034-52. [PMID: 20817848 PMCID: PMC2965535 DOI: 10.1105/tpc.110.075960] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 07/04/2010] [Accepted: 08/19/2010] [Indexed: 05/18/2023]
Abstract
Recently, a number of two LIM-domain containing proteins (LIMs) have been reported to trigger the formation of actin bundles, a major higher-order cytoskeletal assembly. Here, we analyzed the six Arabidopsis thaliana LIM proteins. Promoter-β-glucuronidase reporter studies revealed that WLIM1, WLIM2a, and WLIM2b are widely expressed, whereas PLIM2a, PLIM2b, and PLIM2c are predominantly expressed in pollen. LIM-green fluorescent protein (GFP) fusions all decorated the actin cytoskeleton and increased actin bundle thickness in transgenic plants and in vitro, although with different affinities and efficiencies. Remarkably, the activities of WLIMs were calcium and pH independent, whereas those of PLIMs were inhibited by high pH and, in the case of PLIM2c, by high [Ca(2+)]. Domain analysis showed that the C-terminal domain is key for the responsiveness of PLIM2c to pH and calcium. Regulation of LIM by pH was further analyzed in vivo by tracking GFP-WLIM1 and GFP-PLIM2c during intracellular pH modifications. Cytoplasmic alkalinization specifically promoted release of GFP-PLIM2c but not GFP-WLIM1, from filamentous actin. Consistent with these data, GFP-PLIM2c decorated long actin bundles in the pollen tube shank, a region of relatively low pH. Together, our data support a prominent role of Arabidopsis LIM proteins in the regulation of actin cytoskeleton organization and dynamics in sporophytic tissues and pollen.
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Affiliation(s)
| | | | | | | | | | | | | | - Clément Thomas
- Centre de Recherche Public-Santé, L-1526 Luxembourg, Luxembourg
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82
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Deal RB, Henikoff S. A simple method for gene expression and chromatin profiling of individual cell types within a tissue. Dev Cell 2010; 18:1030-40. [PMID: 20627084 PMCID: PMC2905389 DOI: 10.1016/j.devcel.2010.05.013] [Citation(s) in RCA: 292] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 03/25/2010] [Accepted: 04/14/2010] [Indexed: 11/29/2022]
Abstract
Understanding the production and function of specialized cells during development requires the isolation of individual cell types for analysis, but this is currently a major technical challenge. Here we describe a method for cell type-specific RNA and chromatin profiling that circumvents many of the limitations of current methods for cell isolation. We used in vivo biotin labeling of a nuclear envelope protein in individual cell types followed by affinity isolation of labeled nuclei to measure gene expression and chromatin features of the hair and non-hair cell types of the Arabidopsis root epidermis. We identified hundreds of genes that are preferentially expressed in each cell type and show that genes with the largest expression differences between hair and non-hair cells also show differences between cell types in the trimethylation of histone H3 at lysines 4 and 27. This method should be applicable to any organism that is amenable to transformation.
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Affiliation(s)
- Roger B. Deal
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
- Howard Hughes Medical Institute, Seattle, WA 98109, USA
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83
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Staiger CJ, Poulter NS, Henty JL, Franklin-Tong VE, Blanchoin L. Regulation of actin dynamics by actin-binding proteins in pollen. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1969-86. [PMID: 20159884 DOI: 10.1093/jxb/erq012] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A dynamic network of polymers, the actin cytoskeleton, co-ordinates numerous fundamental cellular processes. In pollen tubes, organelle movements and cytoplasmic streaming, organization of the tip zone, vesicle trafficking, and tip growth have all been linked to actin-based function. Further, during the self-incompatibility response of Papaver rhoeas, destruction of the cytoskeleton is a primary target implicated in the rapid cessation of pollen tube growth and alterations in actin dynamics are associated with the initiation of programmed cell death. Surprisingly, these diverse cellular processes are accomplished with only a small amount of filamentous actin and a huge pool of polymerizable monomers. These observations hint at incredibly fast and complex actin dynamics in pollen. To understand the molecular mechanisms regulating actin dynamics in plant cells, the abundant actin monomer-binding proteins, a major filament nucleator, a family of bundling and severing proteins, and a modulator of growth at the barbed-end of actin filaments have been characterized biochemically. The activities of these proteins are generally consistent with textbook models for actin turnover. For example, the three monomer-binding proteins, profilin, ADF, and CAP, are thought to function synergistically to enhance turnover and the exchange of subunits between monomer and polymer pools. How individual actin filaments behave in living cells, however, remains largely unexplored. Actin dynamics were examined using variable angle epifluorescence microscopy (VAEM) in expanding hypocotyl epidermal cells. Our observations of single filament behaviour are not consistent with filament turnover by treadmilling, but rather represent a novel property called stochastic dynamics. A new model for the dynamic control of actin filament turnover in plant cells is presented.
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Affiliation(s)
- Christopher J Staiger
- Department of Biological Sciences and Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907-2064, USA.
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84
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Engler JDA, Rodiuc N, Smertenko A, Abad P. Plant actin cytoskeleton re-modeling by plant parasitic nematodes. PLANT SIGNALING & BEHAVIOR 2010; 5:213-7. [PMID: 20038822 PMCID: PMC2881263 DOI: 10.4161/psb.5.3.10741] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The cytoskeleton is an important component of the plant's defense mechanism against the attack of pathogenic organisms. Plants however, are defenseless against parasitic root-knot and cyst nematodes and respond to the invasion by the development of a special feeding site that supplies the parasite with nutrients required for the completion of its life cycle. Recent studies of nematode invasion under treatment with cytoskeletal drugs and in mutant plants where normal functions of the cytoskeleton have been affected, demonstrate the importance of the cytoskeleton in the establishment of a feeding site and successful nematode reproduction. It appears that in the case of microfilaments, nematodes hijack the intracellular machinery that regulates actin dynamics and modulate the organization and properties of the actin filament network. Intervening with this process reduces the nematode infection efficiency and inhibits its life cycle. This discovery uncovers a new pathway that can be exploited for the protection of plants against nematodes.
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85
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Kandasamy MK, McKinney EC, Deal RB, Smith AP, Meagher RB. Arabidopsis actin-related protein ARP5 in multicellular development and DNA repair. Dev Biol 2009; 335:22-32. [PMID: 19679120 PMCID: PMC2778271 DOI: 10.1016/j.ydbio.2009.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 07/31/2009] [Accepted: 08/04/2009] [Indexed: 10/20/2022]
Abstract
Actin-related protein 5 (ARP5) is a conserved subunit of the INO80 chromatin-remodeling complex in yeast and mammals. We have characterized the expression and subcellular distribution of Arabidopsis thaliana ARP5 and explored its role in the epigenetic control of multicellular development and DNA repair. ARP5-specific monoclonal antibodies localized ARP5 protein to the nucleoplasm of interphase cells in Arabidopsis and Nicotiana tabacum. ARP5 promoter-reporter fusions and the ARP5 protein are ubiquitously expressed. A null mutant and a severe knockdown allele produced moderately dwarfed plants with all organs smaller than the wild type. The small and slightly deformed organs such as leaves and hypocotyls were composed of small-sized cells. The ratio of leaf stomata to epidermal cells was high in the mutant, which also exhibited a delayed stomatal development compared with the wild type. Mutant plants were hypersensitive to DNA-damaging reagents including hydroxyurea, methylmethane sulfonate, and bleocin, demonstrating a role for ARP5 in DNA repair. Interestingly, the hypersensitivity phenotype of ARP5 null allele arp5-1 is stronger than the severe knockdown allele arp5-2. Moreover, a wild-type transgene fully complemented all developmental and DNA repair mutant phenotypes. Despite the common participation of both ARP4 and ARP5 in the INO80 complex, ARP4- and ARP5-deficient plants displayed only a small subset of common phenotypes and each displayed novel phenotypes, suggesting that in Arabidopsis they have both shared and unique functions.
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Affiliation(s)
| | - Elizabeth C. McKinney
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, GA 30602, USA
| | - Roger B. Deal
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, GA 30602, USA
| | - Aaron P. Smith
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, GA 30602, USA
| | - Richard B. Meagher
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, GA 30602, USA
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86
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Clément M, Ketelaar T, Rodiuc N, Banora MY, Smertenko A, Engler G, Abad P, Hussey PJ, de Almeida Engler J. Actin-depolymerizing factor2-mediated actin dynamics are essential for root-knot nematode infection of Arabidopsis. THE PLANT CELL 2009; 21:2963-79. [PMID: 19794115 PMCID: PMC2768942 DOI: 10.1105/tpc.109.069104] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 08/14/2009] [Accepted: 09/01/2009] [Indexed: 05/19/2023]
Abstract
Reorganization of the actin and microtubule networks is known to occur in targeted vascular parenchymal root cells upon infection with the nematode Meloidogyne incognita. Here, we show that actin-depolymerizing factor (ADF) is upregulated in the giant feeding cells of Arabidopsis thaliana that develop upon nematode infection and that knockdown of a specific ADF isotype inhibits nematode proliferation. Analysis of the levels of transcript and the localization of seven ADF genes shows that five are upregulated in galls that result from the infection and that ADF2 expression is particularly increased between 14 and 21 d after nematode inoculation. Further analysis of ADF2 function in inducible RNA interference lines designed to knock down ADF2 expression reveals that this protein is required for normal cell growth and plant development. The net effect of decreased levels of ADF2 is F-actin stabilization in cells, resulting from decreased F-actin turnover. In nematode-infected plants with reduced levels of ADF2, the galls containing the giant feeding cells and growing nematodes do not develop due to the arrest in growth of the giant multinucleate feeding cells, which in turn is due to an aberrant actin network.
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Affiliation(s)
- Mathilde Clément
- Unité Mixte de Recherches Interactions Biotiques et Santé Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Nice-Sophia Antipolis, F-06903 Sophia Antipolis, France
| | - Tijs Ketelaar
- Laboratory of Plant Cell Biology, Wageningen University, 6703 BD Wageningen, The Netherlands
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom
| | - Natalia Rodiuc
- Unité Mixte de Recherches Interactions Biotiques et Santé Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Nice-Sophia Antipolis, F-06903 Sophia Antipolis, France
| | - Mohamed Youssef Banora
- Unité Mixte de Recherches Interactions Biotiques et Santé Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Nice-Sophia Antipolis, F-06903 Sophia Antipolis, France
| | - Andrei Smertenko
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom
| | - Gilbert Engler
- Unité Mixte de Recherches Interactions Biotiques et Santé Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Nice-Sophia Antipolis, F-06903 Sophia Antipolis, France
| | - Pierre Abad
- Unité Mixte de Recherches Interactions Biotiques et Santé Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Nice-Sophia Antipolis, F-06903 Sophia Antipolis, France
| | - Patrick J. Hussey
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom
| | - Janice de Almeida Engler
- Unité Mixte de Recherches Interactions Biotiques et Santé Végétale, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université de Nice-Sophia Antipolis, F-06903 Sophia Antipolis, France
- Address correspondence to
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87
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Chen N, Qu X, Wu Y, Huang S. Regulation of actin dynamics in pollen tubes: control of actin polymer level. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2009; 51:740-750. [PMID: 19686371 DOI: 10.1111/j.1744-7909.2009.00850.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Actin cytoskeleton undergoes rapid reorganization in response to internal and external cues. How the dynamics of actin cytoskeleton are regulated, and how its dynamics relate to its function are fundamental questions in plant cell biology. The pollen tube is a well characterized actin-based cell morphogenesis in plants. One of the striking features of actin cytoskeleton characterized in the pollen tube is its surprisingly low level of actin polymer. This special phenomenon might relate to the function of actin cytoskeleton in pollen tubes. Understanding the molecular mechanism underlying this special phenomenon requires careful analysis of actin-binding proteins that modulate actin dynamics directly. Recent biochemical and biophysical analyses of several highly conserved plant actin-binding proteins reveal unusual and unexpected properties, which emphasizes the importance of carefully analyzing their action mechanism and cellular activity. In this review, we highlight an actin monomer sequestering protein, a barbed end capping protein and an F-actin severing and dynamizing protein in plant. We propose that these proteins function in harmony to regulate actin dynamics and maintain the low level of actin polymer in pollen tubes.
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Affiliation(s)
- Naizhi Chen
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
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88
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Tian M, Chaudhry F, Ruzicka DR, Meagher RB, Staiger CJ, Day B. Arabidopsis actin-depolymerizing factor AtADF4 mediates defense signal transduction triggered by the Pseudomonas syringae effector AvrPphB. PLANT PHYSIOLOGY 2009; 150:815-24. [PMID: 19346440 PMCID: PMC2689984 DOI: 10.1104/pp.109.137604] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 04/01/2009] [Indexed: 05/19/2023]
Abstract
The actin cytoskeleton has been implicated in plant defenses against pathogenic fungi and oomycetes with limited, indirect evidence. To date, there are no reports linking actin with resistance against phytopathogenic bacteria. The dynamic behavior of actin filaments is regulated by a diverse array of actin-binding proteins, among which is the Actin-Depolymerizing Factor (ADF) family of proteins. Here, we demonstrate that actin dynamics play a role in the activation of gene-for-gene resistance in Arabidopsis (Arabidopsis thaliana) following inoculation with the phytopathogenic bacterium Pseudomonas syringae pv tomato. Using a reverse genetics approach, we explored the roles of Arabidopsis ADFs in plant defenses. AtADF4 was identified as being specifically required for resistance triggered by the effector AvrPphB but not AvrRpt2 or AvrB. Recombinant AtADF4 bound to monomeric actin (G-actin) with a marked preference for the ADP-loaded form and inhibited the rate of nucleotide exchange on G-actin, indicating that AtADF4 is a bona fide actin-depolymerizing factor. Exogenous application of the actin-disrupting agent cytochalasin D partially rescued the Atadf4 mutant in the AvrPphB-mediated hypersensitive response, demonstrating that AtADF4 mediates defense signaling through modification of the actin cytoskeleton. Unlike the mechanism by which the actin cytoskeleton confers resistance against fungi and oomycetes, AtADF4 is not involved in resistance against pathogen entry. Collectively, this study identifies AtADF4 as a novel component of the plant defense signaling pathway and provides strong evidence for actin dynamics as a primary component that orchestrates plant defenses against P. syringae.
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Affiliation(s)
- Miaoying Tian
- Department of Plant Pathology, Michigan State University, East Lansing, Michigan 48824-1311, USA
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89
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Chi J, Wang X, Zhou H, Zhang G, Sun Y, Li Z, Ma Z. Molecular cloning and characterization of the actin-depolymerizing factor gene in Gossypium barbadense. Genes Genet Syst 2009; 83:383-91. [PMID: 19168989 DOI: 10.1266/ggs.83.383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The Sea Island cotton (Gossypium barbadense L.) has been highly valued in verticillium wilt resistance and many fiber qualities including fiber length, strength and fineness. To identify whether it had some special genes in fiber development in comparison with the Upland cotton (G. hirsutum L.), an actin-depolymerizing factor (ADF) gene was cloned and characterized in this research. A 420 bp open reading frame of the cloned gene, named GbADF1, encoded a protein of 139 amino acids, including 39.57% nonpolar amino acids, 17.27% acidic amino acids, 15.83% basic amino acids and 31.92% hydrophobic amino acids. Its molecular weight was about 15 kDa, and pI 5.04. GbADF1 contained two conserved domains, 6-Ser and the PIP2/actin binding site. Its amino acid sequence was similar to the ADF/cofilin family of other plants. Compared with cDNA sequence, the GbADF1 gene contained one intron near the 3' end in genomic sequence. Semi-quantitative RT-PCR result showed that GbADF1 was a constitutive expression gene in cotton, and higher expression level was detected in fibers than in trophic tissues. The GbADF1 was successfully expressed as a fusion protein in Escherichia coli BL21 (DE3). The molecular weight was firstly calculated by SDS-PAGE. Western blotting analysis confirmed the existence of a protein corresponding to GbADF1. The structure of GbADF1 was different from that of other ADF genes in higher plant, although the coding sequences of all cloned ADFs were highly conserved.
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Affiliation(s)
- Jina Chi
- Key Laboratory of Crop Germplasm Resources of Hebei Province, Agricultural University of Hebei, Hebei, China
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90
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Kandasamy MK, McKinney EC, Meagher RB. A single vegetative actin isovariant overexpressed under the control of multiple regulatory sequences is sufficient for normal Arabidopsis development. THE PLANT CELL 2009; 21:701-18. [PMID: 19304937 PMCID: PMC2671709 DOI: 10.1105/tpc.108.061960] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 02/12/2009] [Accepted: 02/24/2009] [Indexed: 05/18/2023]
Abstract
The relative significance of gene regulation and protein isovariant differences remains unexplored for most gene families, particularly those participating in multicellular development. Arabidopsis thaliana encodes three vegetative actins, ACT2, ACT7, and ACT8, in two ancient and highly divergent subclasses. Mutations in any of these differentially expressed actins revealed only mild phenotypes. However, double mutants were extremely dwarfed, with altered cell and organ morphology and an aberrant F-actin cytoskeleton (e.g., act2-1 act7-4 and act8-2 act7-4) or totally root-hairless (e.g., act2-1 act8-2). Our studies suggest that the three vegetative actin genes and protein isovariants play distinct subclass-specific roles during plant morphogenesis. For example, during root development, ACT7 was involved in root growth, epidermal cell specification, cell division, and root architecture, and ACT2 and ACT8 were essential for root hair tip growth. Also, genetic complementation revealed that the ACT2 and ACT8 isovariants, but not ACT7, fully rescued the root hair growth defects of single and double mutants. Moreover, we synthesized fully normal plants overexpressing the ACT8 isovariant from multiple actin regulatory sequences as the only vegetative actin in the act2-1 act7-4 background. In summary, it is evident that differences in vegetative actin gene regulation and the diversity in actin isovariant sequences are essential for normal plant development.
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Affiliation(s)
- Muthugapatti K Kandasamy
- Department of Genetics, Davison Life Sciences Complex, University of Georgia, Athens, Georgia 30602, USA
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91
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Burgos-Rivera B, Ruzicka DR, Deal RB, McKinney EC, King-Reid L, Meagher RB. ACTIN DEPOLYMERIZING FACTOR9 controls development and gene expression in Arabidopsis. PLANT MOLECULAR BIOLOGY 2008; 68:619-32. [PMID: 18830798 PMCID: PMC2811079 DOI: 10.1007/s11103-008-9398-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 08/31/2008] [Indexed: 05/20/2023]
Abstract
Actin depolymerizing factors (ADF/cofilin) modulate the rate of actin filament turnover, networking cellular signals into cytoskeletal-dependent developmental pathways. Plant and animal genomes encode families of diverse ancient ADF isovariants. One weakly but ubiquitously expressed member of the Arabidopsis ADF gene family, ADF9, is moderately expressed in the shoot apical meristem (SAM). Mutant alleles adf9-1 and adf9-2 showed a 95% and 50% reduction in transcript levels, respectively. Compared to wild-type, mutant seedlings and plants were significantly smaller and adult mutant plants had decreased numbers of lateral branches and a reduced ability to form callus. The mutants flowered very early during long-day light cycles, but not during short days. adf9-1showed a several-fold lower expression of FLOWERING LOCUS C (FLC), a master repressor of the transition to flowering, and increased expression of CONSTANS, an activator of flowering. Transgenic ADF9 expression complemented both developmental and gene expression phenotypes. FLC chromatin from adf9-1 plants contained reduced levels of histone H3 lysine 4 trimethylation and lysine 9 and 14 acetylation, as well as increased nucleosome occupancy consistent with a less active chromatin state. We propose that ADF9 networks both cytoplasmic and nuclear processes within the SAM to control multicellular development.
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Affiliation(s)
| | | | - Roger B. Deal
- Fred Hutchinson Cancer Research Center, 1100 Fairview Ave North, Seattle, WA 98109, USA
| | | | - Lori King-Reid
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
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92
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Cruz JR, Moreno Díaz de la Espina S. Subnuclear compartmentalization and function of actin and nuclear myosin I in plants. Chromosoma 2008; 118:193-207. [PMID: 18982342 DOI: 10.1007/s00412-008-0188-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 10/02/2008] [Accepted: 10/06/2008] [Indexed: 01/08/2023]
Abstract
Actins are highly conserved proteins that serve as the basic building blocks of cytoskeletal microfilaments. In animal cells, specific nuclear actin adopts unconventional conformations that are involved in multiple nuclear functions and that associate with nuclear actin binding proteins. However, there is practically no information available about nuclear actin in plants. Indeed, actin has not been detected in the nuclear proteomes of many plants, and orthologs of the main structural nuclear actin-binding proteins have yet to be identified. Here, we have investigated the characteristics, intranuclear compartmentalization, and function of actin in isolated Allium cepa nuclei as well as that of its motor protein nuclear myosin I (NMI). Using conformation-specific antibodies for nuclear actin isoforms, ss-actin, and NMI, the distribution of these proteins was studied in Western blots and by immunocytochemistry. Moreover, the participation of nuclear actin in transcription was analyzed in run on in situ assays and inhibition of RNA polymerases I and II. We show that actin isoforms with distinct solubilities are present in onion nuclei with a consistent subnuclear compartmentalization. Actin and NMI are highly enriched in foci that are similar to transcription foci, although actin is also distributed diffusely in the nucleus and nucleolus as well as accumulating in a subset of the Cajal bodies. Immunogold labeling identified both proteins in the nuclear transcription subdomains and in other subnuclear compartments. In addition, actin and NMI were diffusely distributed in the nuclear matrix.
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Affiliation(s)
- J R Cruz
- Department of Plant Biology, Centro Investigaciones Biológicas, CSIC, Madrid, Spain.
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93
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Passarinho P, Ketelaar T, Xing M, van Arkel J, Maliepaard C, Hendriks MW, Joosen R, Lammers M, Herdies L, den Boer B, van der Geest L, Boutilier K. BABY BOOM target genes provide diverse entry points into cell proliferation and cell growth pathways. PLANT MOLECULAR BIOLOGY 2008; 68:225-37. [PMID: 18663586 DOI: 10.1007/s11103-008-9364-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Accepted: 06/05/2008] [Indexed: 05/22/2023]
Abstract
Ectopic expression of the Brassica napus BABY BOOM (BBM) AP2/ERF transcription factor is sufficient to induce spontaneous cell proliferation leading primarily to somatic embryogenesis, but also to organogenesis and callus formation. We used DNA microarray analysis in combination with a post-translationally regulated BBM:GR protein and cycloheximide to identify target genes that are directly activated by BBM expression in Arabidopsis seedlings. We show that BBM activated the expression of a largely uncharacterized set of genes encoding proteins with potential roles in transcription, cellular signaling, cell wall biosynthesis and targeted protein turnover. A number of the target genes have been shown to be expressed in meristems or to be involved in cell wall modifications associated with dividing/growing cells. One of the BBM target genes encodes an ADF/cofilin protein, ACTIN DEPOLYMERIZING FACTOR9 (ADF9). The consequences of BBM:GR activation on the actin cytoskeleton were followed using the GFP:FIMBRIN ACTIN BINDING DOMAIN2 (GFP:FABD) actin marker. Dexamethasone-mediated BBM:GR activation induced dramatic changes in actin organization resulting in the formation of dense actin networks with high turnover rates, a phenotype that is consistent with cells that are rapidly undergoing cytoplasmic reorganization. Together the data suggest that the BBM transcription factor activates a complex network of developmental pathways associated with cell proliferation and growth.
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Affiliation(s)
- Paul Passarinho
- Plant Research International, P.O. Box 16, 6700 AA Wageningen, The Netherlands
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94
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Augustine RC, Vidali L, Kleinman KP, Bezanilla M. Actin depolymerizing factor is essential for viability in plants, and its phosphoregulation is important for tip growth. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:863-75. [PMID: 18298672 DOI: 10.1111/j.1365-313x.2008.03451.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Actin depolymerizing factor (ADF)/cofilin is important for regulating actin dynamics, and in plants is thought to be required for tip growth. However, the degree to which ADF is necessary has been elusive because of the presence of multiple ADF isoforms in many plant species. In the moss Physcomitrella patens, ADF is encoded by a single, intronless gene. We used RNA interference to demonstrate that ADF is essential for plant viability. Loss of ADF dramatically alters the organization of the F-actin cytoskeleton, and leads to an inhibition of tip growth. We show that ADF is subject to phosphorylation in vivo, and using complementation studies we show that mutations of the predicted phosphorylation site partially rescue plant viability, but with differential affects on tip growth. Specifically, the unphosphorylatable ADF S6A mutant generates small polarized plants with normal F-actin organization, whereas the phosphomimetic S6D mutant generates small, unpolarized plants with a disorganized F-actin cytoskeleton. These data indicate that phosphoregulation at serine 6 is required for full ADF function in vivo, and, in particular, that the interaction between ADF and actin is important for tip growth.
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Affiliation(s)
- Robert C Augustine
- Biology Department, University of Massachusetts, Amherst, 611 North Pleasant Street, University of Massachusetts, Amherst, MA 01003-9297, USA
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Meagher RB, Kandasamy MK, McKinney EC. Multicellular development and protein-protein interactions. PLANT SIGNALING & BEHAVIOR 2008; 3:333-6. [PMID: 19841663 PMCID: PMC2634275 DOI: 10.4161/psb.3.5.5343] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Accepted: 11/28/2007] [Indexed: 05/20/2023]
Abstract
The macroevolution of organs and tissues in higher plants and animals may have been contingent upon the expansion of numerous gene families encoding interacting proteins. For example, there are dozens of gene families encoding actin cytoskeletal proteins that elaborate intercellular structures influencing development. Once gene family members evolve compartmentalized expression, protein isovariants are free to coevolve new interacting partners that may be incompatible with other related protein networks. Ancient classes of actin isovariants and actin-binding proteins are clear examples of such coevolving networks. Ectopic expression and suppression studies were used to dissect these interactions. In higher plants, the ectopic expression of a reproductive actin isovariant in vegetative cell types causes aberrant reorganization of the F-actin cytoskeleton and bizarre development of most organs and tissues. In contrast, overexpression of vegetative actin in vegetative cell types has little effect. The extreme ectopic actin expression phenotypes are suppressed by the coectopic expression of reproductive profilin or actin depolymerizing factor (ADF/cofilin) isovariants, but not by the overexpression of vegetative profilin or ADF. These data provide evidence for the coevolution of organ-specific protein-protein interactions. Thus, understanding the contingent relationships between the evolution of organ-specific isovariant networks and organ origination may be key to explaining multicellular development.
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Affiliation(s)
- Richard B Meagher
- Department of Genetics; Davison Life Sciences Building; University of Georgia; Athens, Georgia USA
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Kandasamy MK, McKinney EC, Meagher RB. ACTIN-RELATED PROTEIN8 encodes an F-box protein localized to the nucleolus in Arabidopsis. PLANT & CELL PHYSIOLOGY 2008; 49:858-63. [PMID: 18385164 PMCID: PMC2953251 DOI: 10.1093/pcp/pcn053] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Arabidopsis encodes six nuclear actin-related proteins (ARPs), among them ARP8 is unique in having an F-box domain and an actin homology domain. Analysis of the ARP8 promoter-beta-glucuronidase (GUS) fusion suggests that ARP8 is ubiquitously expressed in all organs and cell types. Immunocytochemical analysis with ARP8-specific monoclonal antibodies revealed that ARP8 protein is localized to the nucleolus in interphase cells and dispersed in the cytoplasm in mitotic cells. The cell cycle-dependent subcellular patterns of distribution of ARP8 are conserved in other members of Brassicaceae. Our findings provide the first insight into the possible contributions of plant ARP8 to nucleolar functions.
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Kandasamy MK, Burgos-Rivera B, McKinney EC, Ruzicka DR, Meagher RB. Class-specific interaction of profilin and ADF isovariants with actin in the regulation of plant development. THE PLANT CELL 2007; 19:3111-26. [PMID: 17933902 PMCID: PMC2174723 DOI: 10.1105/tpc.107.052621] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 09/06/2007] [Accepted: 09/24/2007] [Indexed: 05/20/2023]
Abstract
Two ancient and highly divergent actin-based cytoskeletal systems have evolved in angiosperms. Plant genomes encode complex actin and actin binding protein (ABP) gene families, most of which are phylogenetically grouped into gene classes with distinct vegetative or constitutive and reproductive expression patterns. In Arabidopsis thaliana, ectopic expression of high levels of a reproductive class actin, ACT1, in vegetative tissues causes severe dwarfing of plants with aberrant organization of most plant organs and cell types due to a severely altered actin cytoskeletal architecture. Overexpression of the vegetative class actin ACT2 to similar levels, however, produces insignificant phenotypic changes. We proposed that the misexpression of the pollen-specific ACT1 in vegetative cell types affects the dynamics of actin due to its inappropriate interaction with endogenous vegetative ABPs. To examine the functionally distinct interactions among the major classes of actins and ABPs, we ectopically coexpressed reproductive profilin (PRF4) or actin-depolymerizing factor (ADF) isovariants (e.g., ADF7) with ACT1. Our results demonstrated that the coexpression of these reproductive, but not vegetative, ABP isovariants suppressed the ectopic ACT1 expression phenotypes and restored wild-type stature and normal actin cytoskeletal architecture to the double transgenic plants. Thus, the actins and ABPs appear to have evolved class-specific, protein-protein interactions that are essential to the normal regulation of plant growth and development.
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Affiliation(s)
- Muthugapatti K Kandasamy
- Department of Genetics, Davison Life Sciences Building, University of Georgia, Athens, Georgia 30602, USA
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