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Godwin J, Raviv B, Grafi G. Dead Pericarps of Dry Fruits Function as Long-Term Storage for Active Hydrolytic Enzymes and Other Substances That Affect Germination and Microbial Growth. PLANTS 2017; 6:plants6040064. [PMID: 29257090 PMCID: PMC5750640 DOI: 10.3390/plants6040064] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/30/2017] [Accepted: 11/30/2017] [Indexed: 11/16/2022]
Abstract
It is commonly assumed that dead pericarps of dry indehiscent fruits have evolved to provide an additional physical layer for embryo protection and as a means for long distance dispersal. The pericarps of dry fruits undergo programmed cell death (PCD) during maturation whereby most macromolecules such DNA, RNA, and proteins are thought to be degraded and their constituents remobilized to filial tissues such as embryo and endosperm. We wanted to test the hypothesis that the dead pericarp represents an elaborated layer that is capable of storing active proteins and other substances for increasing survival rate of germinating seeds. Using in gel assays we found that dead pericarps of both dehiscent and indehiscent dry fruits of various plant species including Arabidopsis thaliana and Sinapis alba release upon hydration multiple active hydrolytic enzymes that can persist in an active form for decades, including nucleases, proteases, and chitinases. Proteomic analysis of indehiscent pericarp of S. alba revealed multiple proteins released upon hydration, among them proteases and chitinases, as well as proteins involved in reactive oxygen species (ROS) detoxification and cell wall modification. Pericarps appear to function also as a nutritional element-rich storage for nitrate, potassium, phosphorus, sulfur, and others. Sinapis alba dehiscent and indehiscent pericarps possess germination inhibitory substances as well as substances that promote microbial growth. Collectively, our study explored previously unknown features of the dead pericarp acting also as a reservoir of biological active proteins, and other substances capable of “engineering” the microenvironment for the benefit of the embryo.
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Affiliation(s)
- James Godwin
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel.
| | - Buzi Raviv
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel.
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel.
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Raviv B, Aghajanyan L, Granot G, Makover V, Frenkel O, Gutterman Y, Grafi G. The dead seed coat functions as a long-term storage for active hydrolytic enzymes. PLoS One 2017; 12:e0181102. [PMID: 28700755 PMCID: PMC5507414 DOI: 10.1371/journal.pone.0181102] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 06/25/2017] [Indexed: 12/31/2022] Open
Abstract
Seed development culminates in programmed cell death (PCD) and hardening of organs enclosing the embryo (e.g., pericarp, seed coat) providing essentially a physical shield for protection during storage in the soil. We examined the proposal that dead organs enclosing embryos are unique entities that store and release upon hydration active proteins that might increase seed persistence in soil, germination and seedling establishment. Proteome analyses of dead seed coats of Brassicaceae species revealed hundreds of proteins being stored in the seed coat and released upon hydration, many are stress-associated proteins such as nucleases, proteases and chitinases. Functional analysis revealed that dead seed coats function as long-term storage for multiple active hydrolytic enzymes (e.g., nucleases) that can persist in active forms for decades. Substances released from the dead seed coat of the annual desert plant Anastatica hierochuntica displayed strong antimicrobial activity. Our data highlighted a previously unrecognized feature of dead organs enclosing embryos (e.g., seed coat) functioning not only as a physical shield for embryo protection but also as a long-term storage for active proteins and other substances that are released upon hydration to the “seedsphere” and could contribute to seed persistence in the soil, germination and seedling establishment.
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Affiliation(s)
- Buzi Raviv
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Lusine Aghajanyan
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Gila Granot
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Vardit Makover
- The Zuckerberg Institute for Water Research, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Omer Frenkel
- Department of Plant Pathology and Weed Research, ARO, The Volcani Center, Bet Dagan, Israel
| | - Yitzchak Gutterman
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Gideon Grafi
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
- * E-mail:
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The dead, hardened floral bracts of dispersal units of wild wheat function as storage for active hydrolases and in enhancing seedling vigor. PLoS One 2017; 12:e0177537. [PMID: 28493968 PMCID: PMC5426743 DOI: 10.1371/journal.pone.0177537] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 04/28/2017] [Indexed: 12/02/2022] Open
Abstract
It is commonly assumed that the dead, hardened floral bracts of the dispersal unit of grasses have been evolved to protect seeds from predation and / or assist in fruit/caryopsis dispersal. While these structures have important agronomical and economical implications, their adaptive value has not been fully explored. We investigated the hypothesis that the maternally derived hardened floral bracts have been evolved not just as a means for caryopsis protection and dispersal, but also as storage for substances that might affect seed germination and seedling vigor. Dead glumes as well as lemmas and paleas of wild emmer wheat (Triticum turgidum var dicoccoides) were found to store and release upon hydration active hydrolases including nucleases and chitinases. High nuclease activity was released upon hydration from glumes derived from wild strains of wheat including Triticum urartu and wild emmer wheat, while very low nuclease activity was detected in glumes derived from domesticated, free-threshing wheat cultivars (e.g., durum wheat). Germination from the intact dispersal unit of wild emmer wheat was delayed, but post germination growth was better than those of separated caryopses. Most notable was a significant increase in lateral root production on seedlings germinated from the intact dispersal unit. Proteome analysis of wild emmer wheat glumes revealed many proteins stored and released upon hydration including S1-type nucleases, peptidases, antifungal hydrolases such as chitinases and β-1,3-glucanase as well as pectin acetylesterase, a protein involved in cell wall degradation and remodeling. Also, reactive oxygen species (ROS)-detoxifying enzymes such as superoxide dismutase and ascorbate peroxidase were overrepresented in dead glumes of wild emmer wheat. Thus our study highlighted previously unknown features of the dispersal unit in wild wheat in which the dead, hardened floral bracts enclosing the caryopsis store active hydrolases and nutritional elements and probably growth promoting substances that facilitate seed longevity and germination and increase seedling vigor.
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Givaty-Rapp Y, Yadav NS, Khan A, Grafi G. S1-Type Endonuclease 2 in Dedifferentiating Arabidopsis Protoplasts: Translocation to the Nucleus in Senescing Protoplasts Is Associated with De-Glycosylation. PLoS One 2017; 12:e0170067. [PMID: 28068427 PMCID: PMC5222596 DOI: 10.1371/journal.pone.0170067] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 12/28/2016] [Indexed: 11/18/2022] Open
Abstract
Cell dedifferentiation characterizes the transition of leaf cells to protoplasts and is accompanied by global chromatin decondensation. Here we show that in Arabidopsis, chromocentric chromatin undergoes prompt and gradual decondensation upon protoplasting. We hypothesized that prompt chromatin decondensation is unlikely to be driven solely by epigenetic means and other factors might be involved. We investigated the possibility that S1-type endonucleases are involved in prompt chromatin decondensation via their capability to target and cleave unpaired regions within superhelical DNA, leading to chromatin relaxation. We showed that the expression and activity of the S1-type endonuclease 2 (ENDO2) is upregulated in dedifferentiating protoplasts concomitantly with chromatin decondensation. Mutation of the ENDO2 gene did not block or delay chromocentric chromatin decondensation upon protoplasting. Further study showed that ENDO2 subcellular localization is essentially cytoplasmic (endoplasmic reticulum-associated) in healthy cells, but often localized to the nucleus and in senescing/dying cells it was associated with fragmented nuclei. Using in gel nuclease assays we identified two ENDO2 variants, designated N1 (cytoplasmic variant) and N2 (cytoplasmic and nuclear variant), and based on their capability to bind concanavalin A (ConA), they appear to be glycosylated and de-glycosylated (or decorated with ConA non-binding sugars), respectively. Our data showed that the genome is responding promptly to acute stress (protoplasting) by acquiring decondensation state, which is not dependent on ENDO2 activity. ENDO2 undergoes de-glycosylation and translocation to the nucleus where it is involved in early stages of cell death probably by introducing double strand DNA breaks into superhelical DNA leading to local chromatin relaxation and fragmentation of nuclei.
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Affiliation(s)
- Yemima Givaty-Rapp
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Narendra Singh Yadav
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Asif Khan
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Gideon Grafi
- French Associates Institute of Agriculture and Biotechnology of Drylands, The Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
- * E-mail:
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Granot G, Morgenstern Y, Khan A, Rapp YG, Pesok A, Nevo E, Grafi G. Internucleosomal DNA fragmentation in wild emmer wheat is catalyzed by S1-type endonucleases translocated to the nucleus upon induction of cell death. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1849:239-46. [PMID: 25497371 DOI: 10.1016/j.bbagrm.2014.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/25/2014] [Accepted: 12/03/2014] [Indexed: 11/17/2022]
Abstract
Leaves of cereal plants display nucleosomal fragmentation of DNA attributed to the action of nucleases induced during program cell death (PCD). Yet, the specific nuclease activity responsible for generating double strand DNA breaks (DSBs) that lead to DNA fragmentation has not been fully described. Here, we characterized a Ca2+/Mg2+-dependent S1-type endonuclease activity in leaves of wild emmer wheat (Triticum dicoccoides Köern.) capable of introducing DSBs as demonstrated by the conversion of supercoiled plasmid DNA into a linear duplex DNA. In-gel nuclease assay revealed a nuclease of about 35 kDa capable of degrading both single stranded DNA and RNA. We further showed that the endonuclease activity can be purified on Concanavalin A and treatment with peptide-N-glycosidase F (PNGase F) did not abolish its activity. Furthermore, ConA-associated endonuclease was capable of generating nucleosomal DNA fragmentation in tobacco nuclei. Since S1-type endonucleases lack canonical nuclear localization signal it was necessary to determine their subcellular localization. To this end, a cDNA encoding for a putative 34 kDa S1-type nuclease, designated TaS1-like (TaS1L) was synthesized based on available sequence data of Triticum aestivum and fused with RFP. Introduction into protoplasts showed that TaS1L-RFP is cytoplasmic 24h post transformation but gradually turn nuclear at 48 h concomitantly with induction of cell death. Our results suggest that DNA fragmentation occurring in leaves of wild emmer wheat may be attributed to S1-type endonuclease(s) that reside in the cytoplasm but translocate to the nucleus upon induction of cell death.
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Affiliation(s)
- Gila Granot
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Yaakov Morgenstern
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Asif Khan
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Yemima Givaty Rapp
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Anat Pesok
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Eviatar Nevo
- Institute of Evolution, University of Haifa, 199 Aba-Hushi Avenue Mount Carmel, Haifa 3498838, Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
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Florentin A, Damri M, Grafi G. Stress induces plant somatic cells to acquire some features of stem cells accompanied by selective chromatin reorganization. Dev Dyn 2013; 242:1121-33. [DOI: 10.1002/dvdy.24003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 06/11/2013] [Accepted: 06/11/2013] [Indexed: 12/13/2022] Open
Affiliation(s)
- Assa Florentin
- French Associates Institute for Agriculture and Biotechnology of Drylands; Jacob Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Midreshet Ben-Gurion Israel
| | - Meytal Damri
- French Associates Institute for Agriculture and Biotechnology of Drylands; Jacob Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Midreshet Ben-Gurion Israel
- The Shraga Segal Department of Microbiology and Immunology; Faculty of Health Sciences; Center for Multidisciplinary Research on Aging; Ben-Gurion University of the Negev; Beer Sheva Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands; Jacob Blaustein Institutes for Desert Research; Ben-Gurion University of the Negev; Midreshet Ben-Gurion Israel
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UVI31+ is a DNA endonuclease that dynamically localizes to chloroplast pyrenoids in C. reinhardtii. PLoS One 2012; 7:e51913. [PMID: 23284814 PMCID: PMC3524116 DOI: 10.1371/journal.pone.0051913] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 11/07/2012] [Indexed: 11/28/2022] Open
Abstract
UVI31+ is an evolutionarily conserved BolA family protein. In this study we examine the presence, localization and possible functions of this protein in the context of a unicellular alga, Chlamydomonas reinhardtii. UVI31+ in C. reinhardtii exhibits DNA endonuclease activity and is induced upon UV stress. Further, UVI31+ that normally localizes to the cell wall and pyrenoid regions gets redistributed into punctate foci within the whole chloroplast, away from the pyrenoid, upon UV stress. The observed induction upon UV-stress as well as the endonuclease activity suggests plausible role of this protein in DNA repair. We have also observed that UV31+ is induced in C. reinhardtii grown in dark conditions, whereby the protein localization is enhanced in the pyrenoid. Biomolecular interaction between the purified pyrenoids and UVI31+ studied by NMR demonstrates the involvement of the disordered loop domain of the protein in its interaction.
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Grafi G, Florentin A, Ransbotyn V, Morgenstern Y. The stem cell state in plant development and in response to stress. FRONTIERS IN PLANT SCIENCE 2011; 2:53. [PMID: 22645540 PMCID: PMC3355748 DOI: 10.3389/fpls.2011.00053] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 09/03/2011] [Indexed: 05/18/2023]
Abstract
Stem cells are commonly defined by their developmental capabilities, namely, self-renewal and multitype differentiation, yet the biology of stem cells and their inherent features both in plants and animals are only beginning to be elucidated. In this review article we highlight the stem cell state in plants with reference to animals and the plastic nature of plant somatic cells often referred to as totipotency as well as the essence of cellular dedifferentiation. Based on recent published data, we illustrate the picture of stem cells with emphasis on their open chromatin conformation. We discuss the process of dedifferentiation and highlight its transient nature, its distinction from re-entry into the cell cycle and its activation following exposure to stress. We also discuss the potential hazard that can be brought about by stress-induced dedifferentiation and its major impact on the genome, which can undergo stochastic, abnormal reorganization leading to genetic variation by means of DNA transposition and/or DNA recombination.
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Affiliation(s)
- Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev Midreshet Ben-Gurion, Israel
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Farage-Barhom S, Burd S, Sonego L, Perl-Treves R, Lers A. Expression analysis of the BFN1 nuclease gene promoter during senescence, abscission, and programmed cell death-related processes. JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:3247-58. [PMID: 18603613 PMCID: PMC2529240 DOI: 10.1093/jxb/ern176] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 05/19/2008] [Accepted: 06/03/2008] [Indexed: 05/18/2023]
Abstract
Little is known about the biological role of nucleases induced during plant senescence and programmed cell death (PCD). Arabidopsis BFN1 has been identified as a senescence-associated type I nuclease, whose protein sequence shares high homology with some other senescence- or PCD-associated plant nucleases. To learn about BFN1 regulation, its expression pattern was analysed. A 2.3 kb portion of the 5' promoter sequence of BFN1 was cloned and its ability to activate the GUS reporter gene was examined. Transgenic Arabidopsis and tomato plants harbouring this chimeric construct were analysed for GUS expression. In both, the BFN1 promoter was able specifically to direct GUS expression in senescent leaves, differentiating xylem and the abscission zone of flowers. Thus, at least part of the regulation of BFN1 is mediated at the transcriptional level, and the regulatory elements are recognized in the two different plants. In tomato, specific expression was observed in the leaf and the fruit abscission zones. The BFN1 promoter was also active in other tissues, including developing anthers and seeds, and in floral organs after fertilization. PCD has been implicated in all of these processes, suggesting that in addition to senescence, BFN1 is involved in PCD associated with different development processes in Arabidopsis.
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Affiliation(s)
- Sarit Farage-Barhom
- Department of Postharvest Science of Fresh Produce, Volcani Center, Agricultural Research Organization, Bet Dagan 50250, Israel
- Faculty of Life Science, Bar Ilan University, Ramat Gan, Israel
| | - Shaul Burd
- Department of Postharvest Science of Fresh Produce, Volcani Center, Agricultural Research Organization, Bet Dagan 50250, Israel
| | - Lilian Sonego
- Department of Postharvest Science of Fresh Produce, Volcani Center, Agricultural Research Organization, Bet Dagan 50250, Israel
| | | | - Amnon Lers
- Department of Postharvest Science of Fresh Produce, Volcani Center, Agricultural Research Organization, Bet Dagan 50250, Israel
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Yupsanis T, Symeonidis L, Kalemi T, Moustaka H, Yupsani A. Purification, properties and specificity of an endonuclease from Agropyron elongatum seedlings. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2004; 42:795-802. [PMID: 15596099 DOI: 10.1016/j.plaphy.2004.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2004] [Accepted: 09/08/2004] [Indexed: 05/01/2023]
Abstract
An endonuclease was isolated from 5 days old Agropyron elongatum 8x = Elytrigia turcica McGuire seedlings. The enzyme was purified by means of ammonium sulfate fractionation, DEAE-cellulose and Heparin Sepharose column. The final preparation, named nuclease A, gave a single band after silver staining had followed SDS-electrophoresis that was identified with nuclease activities. The enzyme also showed a single band after activity staining on gel polymerized in the presence of heat denatured DNA (ssDNA)/RNA. The Mr of native enzyme was 36 and the enzyme's moiety consisted of one polypeptide chain. Nuclease A activity was stimulated in the presence of Zn(2+) and was moderately reduced by NaCl yet strongly by spermine. The enzyme had pH optimum 5.5 and isoelectric point (pI) 4.7. It hydrolyzed the nucleic acids in the order ssDNA > dsDNA > or = RNA; hence it was classified as a plant nuclease type I (EC 3.1.30.2). Synthetic homopolyribonucleotides were hydrolyzed in the order polyU > polyI > or = polyA > polyG > polyC. Nuclease A nicked the supercoiled plasmid DNA while it was incapable of hydrolyzing dinucleoside monophosphates. With regard to nuclease A base linkage specificity towards a synthetic 5'-(32)P labeled deoxydecanucleotide [5'-(32)P]CCTGGCAGTT, the enzyme firstly exhibited a preference to Ap downward arrow G bond and then to Gp downward arrow T, Cp downward arrow A and Gp downward arrow G bonds while it was incapable of hydrolyzing the Cp downward arrow C bond. The substrate's products of nuclease A were oligonucleotides with the monoesterified phosphate at the 3' position. Nuclease A may perform a crucial function in the metabolism of nucleic acids during seedling growth and could be used as a biochemical tool for analysis of nucleic acids structure.
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Affiliation(s)
- Traianos Yupsanis
- Laboratory of Biochemistry, Department of Biochemistry, School of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
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Abstract
As the major transporters and distributors of water and minerals, xylem vessels and tracheids are the lifeline of plants. Interestingly, the building blocks of these water pipes are dead tracheary elements and vessel elements that have the process of cell death integrated into their differentiation programme. Using the Zinnia in vitro model system for xylogenesis, a key nuclease that is responsible for nuclear degradation during the terminal stages of tracheary element differentiation has been identified recently.
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Affiliation(s)
- Preeti Dahiya
- Department of Cell and Developmental Biology, John Innes Centre, Colney, Norwich NR4 7UH, UK.
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Aoyagi S, Sugiyama M, Fukuda H. BEN1 and ZEN1 cDNAs encoding S1-type DNases that are associated with programmed cell death in plants. FEBS Lett 1998; 429:134-8. [PMID: 9650576 DOI: 10.1016/s0014-5793(98)00563-8] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We describe the isolation and characterization of cDNAs encoding two DNases that may be involved in the programmed death of plant cells: a 35-kDa nuclease of barley, which had been reported to be secreted from the aleurone layer into the endosperm during germination and may be responsible for the digestion of nuclear DNA in the course of degradation (cell death) of endosperm, and a 43-kDa nuclease of zinnia, which appears transiently in association with differentiation to tracheary elements and is likely to participate in the autolysis at the final step of the differentiation. Genes for these nucleases of barley and zinnia were designated BEN1 and ZEN1, respectively. The amino acid sequence of BEN1 protein deduced from the nucleotide sequence of BEN1 cDNA consisted of 288 residues with a putative signal sequence of 23 residues. RNA gel blot analysis revealed that BEN1 mRNA increased in the embryo-less half seeds of barley in response to the application of gibberellic acid. The deduced amino acid sequence of ZEN1 protein consisted of 303 residues with a putative signal sequence of 25 residues. Temporal accumulation of ZEN1 mRNA was detected during transdifferentiation of zinnia mesophyll cells into tracheary elements. Significant similarities were found among the amino acid sequences of BEN1, ZEN1, nuclease S1 from Aspergillus oryzae, and two other S1-type nucleases.
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Affiliation(s)
- S Aoyagi
- Botanical Gardens, Graduate School of Science, The University of Tokyo, Japan
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