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7. Abstracts of presentations on plant protection issues at the xth international congress of virology: August 11–16,1996 Binyanei haOoma, Jerusalem, Israel Part 2 Plenary Lectures

Author

Ramirez, E., Hernádez, A., Ham, E., Barrón, B. L., Ding, S. W., Li, W. X., Shi, B. J., Symons, R. H., Li, Q., Ryu, K. H., Palukaitis, P., Kaplan, I. B., Palukaitis, P., Kaplan, I. B., Palukaitis, P., Gal-On, A., Kunhara, J., Otsubo, T., Tomaru, K., Tsuda, S., Kinta, M., Lin, T., Johnson, J. E., Porta, C., Taylor, K. M., Spall, V. E., Lomonossoff, G. P., Spall, V. E., Porta, C., Lomonossoff, G. P., Gal-On, A., Meiri, E., Raccah, B., Gaba, V., Ikegami, M., Kawashima, H., Murayama, A., Natsuaki, T., Kageyama, Y., Sugimura, N., Thole, V., Bol, J. F., Deiman, B. A. L. M., Koenen, A. K., Pleij, C. W. A., Chaleeprom, W., Bateson, M. F., Dale, J. L., Badge, J. L., Foster, G. D., Brunt, A. A., Robinson, D., Schubert, J., Rabenstein, F., Merits, A., Yeh, Shyi-Dong, Chiang, Chu-Hui, Wang, Ching-Hsien, Chiang, Chu-Hui, Yeh, Shyi-Dong, Golshani, A., Ivanov, I. G., AbouHaidar, M. G., Rodoni, B. C., Harding, R. M., Bateson, M. F., Dale, J. L., Oertel, U., Fuchs, E., Schubert, J., Yang, S. J., Revere, F., Walter, J., Le Gall, O., Dunez, J., Candresse, T., Lot, H., Souche, S., Kasschau, Kristin D., Carrington, James C., Chiang, A. N., Turner, N. E., Hwang, D. J., Chachulska, A. M., Zagórski, W., Robaglia, C., Chrzanowska, M., Truve, E., Tamm, T., Saarma, M., Makinen, K., Wang, Aiming, Carrier, Karma, Wieczorek, Andrew, Huguenot, Claire, Sanfacon, Helene, Wurscher, M. A., Christensen, F. E., Prody, G. A., Sanchez-Navarro, J. A., Pallas, V., Carson, R., Dagless, E., Lock, S., Turner, R., Foster, G. D., Badge, J. L., Adams, M., Antoniw, J., Brunt, A. A., Phillips, S., Kashiwazaki, S., Seal, S., Karamagioli, M., Druka, Amis, Makhdoom, Rahat, Yitang, Yan, Hull, Roger, Kikkert, M., Bodegom, P., Storms, M., van Lent, J., Kormelink, R., Goldbach, R., De Haan, P., De Rover, A. R., Van Schepen, A., Gielen, J. J. L., Van Grinsven, M. Q. J. M., Livneh, O., Vardi, E., Kuznetsova, L., Aliskevicius, E., Stram, Y., Sela, I., Dinant, S., Kusiak, C., Blaise, F., Chupeau, Y., Astier, S., Albouy, J., Clifford, T. B., Taylor, S. C., Stratford, R., Foster, G. D., Xiao, X. W., Frenkel, M. J., Chu, P., Tabe, L., Shukla, D. D., Ward, C. W., Hwang, Duk-Ju, Turner, Nilgun, Taylor, S. C., Mooney, A., MacFarlane, S. A., Twell, D., Foster, G. D., Jacquet, C., Ravelonandro, M., Bachelier, J. C., Dunez, J., Almási, A., Böddi, B., Szigeti, Z., Ekes, M., Gaborianvi, R., Yankulova, Margarita, Ivanova, Lidia, Adam, G., Guelemerov, S., Nikolaeva, Velitchka, Atanassov, A., Prins, Marcel, de Haan, Peter, Goldbach, Rob, Duan, Y. P., Powell, C. A., Purcifull, D. E., Hiebert, E., Levine, B., Faktor, O., Zeituny, Silvy, Edelbaum, Orit, Sela, L., Marano, Maria-Rosa, Ratcliff, Frank, Baulcombe, David C., van Oers, Monique M., Linthorst, Huub J. M., Bol, John F., Schillberg, S., Zimmermann, S., Drossard, J., Schumann, D., Nahring, J., Fischer, R., Lapidot, Moshe, Arce-Johnson, Patricio, Rivera-Bustamante, Rafael, Beachy, Roger N., Cassidy, Brandt G., Flasinski, Stanislaw, Hajimorad, M. R., Wesley, Varsha, Angel-Diaz, J., Mayo, M. A., Hafner, G. J., May, G. D., Becker, D. K., Harding, R. M., Arntzen, C. J., Dale, J. L., Taylor, S. C., Porter, J., Foster, G. D., Palukaitis, P., Hellwald, K. H., Banerjee, N., Zaitlin, M., Gal-On, A., Wolf, D., Faure, J. E., Pilowsky, M., Cohen, S., Zelcer, A., Hardi, V., Tomassoli, L., Kaniewski, W. K., Mitsky, T., Barba, M., Hou, Y. -M., Ursin, V. M., Sanders, R., Gilbertson, R. L., Gruden, Kristina, Štrukelj, Borut, Brzin, Joze, Ravnikar, Maja, Maganja, Darja Barlič, Kregar, Igor, Maki-Valkama, T., Pehu, T., Valkonen, J., Lento, K., Pehu, E., Zaitlin, M., Kaniewski, W. K., Lawson, E. C., Feldman, J., Zalewski, J., Saarma, M., Kuittinen, T., Valkonen, J., Atiri, G. I., Romero, A., Arroyo, R., Soto, M. J., Martínez-Zapater, J. M., Ponz, F., Gilardi, P., López, L., García-Luque, I., Serra, M. T., Pang, Sheng-Zhi, Jan, Fuh-Jyh, Carney, Kim, Tricoli, David M., Quemada, Hector D., Gonsalves, Dennis, Aboul-Ata, A. E., Thouvenel, J. -C., Marshall, D., Abo-El-Saad, Sh., Satour, M., Mazithulela, G., Mehlo, L., Gahakwa, D., Leech, M., Boulton, M. I., Davies, J. W., Christou, P., Huet, H., Sivamani, E., Ong, C. A., Chen, L., de Kochko, A., Beachy, R. N., Fauquet, C. M., Sithisarn-Burns, P., Maugeri, M. M., Dale, J. L., Smith, G. R., Harding, R. M., Handley, J. A., Harding, R. M., Smith, G. R., Dale, J. L., Graichen, K., Peterka, J., Chu, Paul, Larkin, Phil, Higgins, T. J., Wylie, S., Jones, M. G. K., Somsap, V., Loo, H. P., Li, D., Mathews, A., Jones, M. G. K., Dwyer, G. I., Jones, M. G. K., McCarthy, P. L., Hansen, J., Shiel, P. J., Zemetra, R. S., Wyatt, S. D., Berger, P. H., Ford, C., Collins, N., Rathjen, J., Shams-Bakhsh, M., Paltridge, N., Symons, R. H., Aboul-Ata, A. E., Makkouk, K. M., El-Saied, M. A., El-Hariry, M., Salem, G., Soliman, N. H., Rishi, Narayan, Lodhi, G. P., Bishnoi, S. S., Sangwan, R. B., Sijen, Titia, Wellink, Joan, van Kammen, Ab, Ravelonandro, M., Scorza, R., Bachelier, J., Callahan, A., Levy, L., Dunez, J., Polák, J., Oukropec, I., Kominek, P., Bitoova, M., Cardol, Erwin, Prins, Marcel, Kormelink, Richard, Goldbach, Rob, Baulcombe, D. C., English, J. J., Davenport, G., Ruiz-Perez, T., Mueller, E., Truve, E., Nigul, L., Saarma, M., Kelve, M., Fedorkin, O. N., Denisenko, O. N., Zelenina, D. A., Morozov, S. Yu., Atabekov, J. G., Laliberté, J. -F., Wittmann, S., Plante, Daniel, Fortin, Marc G., Chatel, H., Rodriguez-Alvarado, G., Garcia-Arenal, F., Roossinck, M. J., Palukaitis, P., Roossinck, M. J., Palukaitis, P., Gellatly, D. L., AbouHaidar, M. G., Rasochova, L., Aulik, M., Passmore, B., Falk, B., Miller, W. A., Lin, Na-Sheng, Lin, Biing-Yuan, Hsu, Yau-Heiu, Tamada, T., Kiguchi, T., Saito, M., Kusume, T., Uchino, H., Taliansky, M., Robinson, D., DiSerio, F., Daròs, J. A., Ragozzino, A., Floras, R., Hohn, Thomas, Chen, Gang, Rothnie, Helen, Corsten, Sandra, Fütterer, Johannes, Mikhailov, M. V., Bishop, D. H. L., and Roy, P.

Published
1997
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9. Abstracts of presentations on plant protection issues at the fifth international Mango Symposium Abstracts of presentations on plant protection issues at the Xth international congress of Virology: September 1–6, 1996 Dan Panorama Hotel, Tel Aviv, Israel August 11-16, 1996 Binyanei haoma, Jerusalem, Israel

Author

Peña, J. E., Wysoki, M., Singh, Gajendra, Boscán de M., Nancy, Godoy, Freddy J., Obligado, A., Rossetto, C. J., Ribeiro, I. J. A., Gallo, P. B., Soares, N. B., Sabino, J. C., Martins, A. L. M., Bortoletto, N., Ploetz, R. C., Benscher, D., Vázquez, Aimé, Colls, A., Nagel, Julianne, Schaffer, B., Pinkas, Y., Maymon, M., Freeman, S., Bostros Bastawros, Mikhail, Gosbee, M. J., Johnson, G. I., Joyce, D. C., Irwin, J. A. G., Saaiman, W. C., Prusky, D., Falik, E., Kobiler, I., Fuchs, Y., Zauberman, G., Pesis, E., Ackerman, M., Roth, I., Weksler, A., Yekutiely, O., Waisblum, A., Keinan, A., Ofek, G., Reved, R., Barak, R., Bel, P., Artes, L., Visarathanonth, N., Xu, Z., Ponce de León, L., Muñoz, C., Pérez, L., Diaz de León, F., Kerbel, C., Esparza, S., Bósquez, E., Trinidad, M., Coates, L. M., Cooke, A. W., Dean, J. R., Lucia Duarte, Ana, Alberto Otto, Paulo, Malavasi, Aldo, Lizado, M. C. C., Bautista, M. L., Artes, L. A., Bacalangco, N. S., Farungsang, U., Farungsang, N., Waskar, D. P., Masalkar, S. D., Gaikwad, R. S., Damame, S. V., Bally, Ian S. E., O’Hare, Tim J., Holmes, Rowland J., Atabekov, J. G., Fauquet, Claude M., Tomori, O., Nuss, D. L., Ahlquist, P., Díez, J., Ishikawa, M., Janda, M., Price, B. D., Restrepo-Hartwig, M., Bol, J. F., van Rossum, C. M. A., Garcia, M. L., van der Vossen, E. A. G., Reusken, Chantal B. E. M., Canto, T. R., Gal-On, A., Palukaitis, P., Roossinck, M. J., Flasinski, S., Restrepo-Hartwig, Maria A., Ahlquist, Paul, Smirnyagina, Ekaterina, Lin, Na-Sheng, Nagy, Peter D., Figlerowicz, Marek, Bujarski, Jozef J., Proll, D. F., Guyatt, K. J., Davidson, A. D., Kim, Kook-Hyung, Miller, Eric, Hemenway, Cynthia, Havelda, Z., Dalmay, T., Burgyán, J., Kearney, C. M., Thomson, M., Roland, K. E., Dawson, W. O., Bao, Y., Carter, S. A., Nelson, R. S., Derrick, P. M., Shun Ding, Xin, Eskarous, J. K., Sarkar, S., El-Shamy, M., Chen, J., Sako, N., Yuichiro, W., Ohshima, K., Okada, Y., Felden, Brice, Kuznetsov, Yuri G., Malkin, Alexander J., Greenwood, Aaron, McPherson, Alexander, Ivanov, K. I., Dorokhov, Y. L., Kim, C. H., Sálanki, Katalin, Carrére, Isabelle, Jacquemond, Mireille, Tepfer, Mark, Balazs, Ervin, Sanz, A. I., Serra, M. T., García-Luque, I., Revers, F., Candresse, T., LeGall, O., Souche, S., Lot, H., Dunez, J., Cecchini, E., Milner, J., Al-Kaff, N., Covey, S., Gong, Z., Geri, C., Covey, S. N., Richert-Pöggeler, K. R., Shepherd, R. J., Casper, R., Meiri, Eti, Raccah, B., Gera, A., Singer, S., Allam, E. K., El Afifi, Soheir I., Abo El Nasr, M. A., Abd El Ghaffar, M. H., Elisabeth Johansen, I., Keller, K. E., Hampton, R. O., SÕrensen, Karina, Bishnoi, S. S., Rishi, Narayan, Gumedzoe, M. Y. D., Atissime, K., Yedibahoma, S., Wellink, Joan, Verver, Jan, Bertens, Peter, van Lent, Jan, Goldbach, Rob W., van Kammen, Ab, Lekkerkerker, Annemarie, Taylor, K. M., Spall, V. E., Lomonossoff, G. P., Yu. Morozov, S., Solovyev, A. G., Zelenina, D. A., Savenkov, E. I., Grdzelishvili, V. Z., Morozov, S. Y., Jansen, K. A. J., Wolfs, C. J. A. M., Lohuis, H., Verduin, B. J. M., Stein-Margolina, V. A., Hsu, Y. H., Chang, B. Y., Lin, N. S., Pilartz, Marcel, Jeske, Holger, Verchot, Jeanmarie, Baulcombe, David C., English, David J., Müller, E., Baulcombe, D. C., Malcuit, Isabelle, Kavanagh, Tony, Valkonen, J. P. T., Puurand, Ü., Merits, A., Rabinstein, F., Sorri, O., Saarma, M., Liao, Y. C., Vaquero-Martin, C., Monecke, M., Rohde, W., Prüfer, D., Fischer, R., Antignus, Y., Lachman, O., Pearlsman, M., Cohen, S., Qiu, W. P., Moyer, J. W., Feldhoff, A., Kikkert, M., Kormelink, R., Krczal, G., Peters, D., Szittya, György, Burgyán, József, Wvpijewski, K., Paduch-Cichal, E., Rezler, A., Skrzeczkowska, S., Augustyniak, J., Nemchinov, L., Maiss, E., Hadidi, A., Wittner, Anita, Palkovics, László, Balázs, Ervin, Crescenzi, A., Piazzolla, P., Kheyr-Pour, A., Dafalla, G. A., Lecoq, H., Gronenborn, B., Bauer, U., Laux, I., Hajimorad, M. R., Ding, X. S., Flasinski, Stanislaw, Cassidy, Pour G., Dugdale, B., Beetham, P. R., Harding, R. M., Dale, J. L., Qiu, G., Shaw, J. G., Molnár, A., Más, P., Balsalobre, J. M., Sánchez-Pina, M. A., Pallás, V., Rahontei, J., López, L., Lázara, J. J., Barón, M., Owens, R. A., Steger, G., Hu, Y., Fels, A., Hammond, R. W., Riesner, D., Schröder, A. R. W., Góra, A., Pawlowicz, J., Kierzek, A., Zagorski, W., Baumstark, T., Schiebel, W., Schiebel, R., Axmann, A., Haas, B., Sänger, H. L., Xicai, Yang, Yin, Yie, Feng, Zhu, Yule, Liu, Liangyi, Kang, Po, Tien, Poliyka, H., Staub, U., Wagner, M., Gross, H. J., Sano, Teruo, Ishiguro, Akiro, Fayos, J., Garro, R., Bellés, J. M., Conejero, V., Bonfiglioli, R. G., Webb, D. R., Symons, R. H., El-Dougdoug, K. A., Abo-Zeid, A. A., Ambrós, S., Hernandez, C., Desvignes, J. C. C., Flores, R., d’Aquilio, M., Lisa, V., Boccardo, G., Vera, A., Daròs, J. A., Henkel, J., Spieker, R., Higgins, C., Turley, R., Chamberlain, D., Bateson, M., Dale, J., d’Aquino, L., Ragozzino, A., Henderson, J., Bateson, M. F., Chaleeprom, W., Gibbs, A. J., Graichen, K., Rabenstein, F., Schliephake, E., Smith, H. G., Stevens, M., Sadowy, E., Hulanicka, D., Wegener, B., Martin, M. T., Wetzel, T., Cook, G., Kasdorf, G. G. F., Pietersen, G., Braithwaite, Kathryn S., Gambley, Cherie F., Smith, Grant R., Druka, Arnis, Villegas, Lucille, Dahal, Ganesh, Hull, Roger, Senchugova, N. A., Büchen-Osmond, C., Dallwitz, M. J., Blaine, L. D., Naik, P. S., Sonone, A. B., Kolaskar, A. S., Sgro, J. Y., Palmenberg, A. C., Leclerc, Denis, Hohn, Thomas, Moriones, E., Batlle, A., Luis, M., Alvarez, J., Bernal, J. J., Alonso, J. L., Spak, J., Kubelkova, D., Kuo, T. T., Gachechiladze, K. K., Adamia, R. S., Balardshishvili, N. S., Chanishvili, T. G., Krüger, D. H., Nagy, Tibor, Élö, Péter, Papp, Péter, Orosz, László, Licis, N., Berzins, V., Sariol-Carbelo, Carlos A., RodrCarlos, C. M., Janzen, D., Ward, Colin W., Scott, S. W., Shiel, P. J., Berger, P. H., Aleman, M. E., Beachy, R. N., Fauquet, C. M., Salm, S. N., Rybicki, E. P., Rey, M. E. C., Briddon, R. W., Harper, G., Druka, A., Phillips, S., Brunt, A. A., Hull, R., Hay, Jo, Dasgupta, Indranil, Zaifeng, Fan, Meehan, Brian M., Todd, Daniel, Bunk, Hans-Jörk, Grieco, F., Martelli, G. P., Saldarelli, P., Minafra, A., Morag, A., Mumcuoglu, M., Baybikov, T., Schlesinger, M., Zakay-Rones, Z., Shohat, B., Shohat, M., Miller, M., Shaklay, M., Kalvatchev, Z., Walder, R., Garzaro, D., Barrios, M., Karagöz, Ali, Kuru, Avni, Karim, M. R., Johnson, A. J., Takida, S., Thompson, M. C., Omer, H. M. K., Omer, O. L. M., Biyiti, L., Amvam, R. H., Lamaty, G., Bouchet, P., Xu, J., Hefferon, K. L., Abou Haidar, M. G., and Meng, A. X. X.

Published
1997
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27. A "Gene for Gene" Interaction and Potato Virus X.

Author

Baulcombe, D. C., Köhm, B., Goulden, M. G., Santa-Cruz, S., Forsyth, A., Chapman, S., and Kavanagh, T.

Subjects
POTATO virus X, POTATO disease & pest resistance, PLANT virus genetics, VIRAL genes, COWPEA mosaic virus
Published
1995

28. Short Silencing RNA: The Dark Matter of Genetics?

Author

Baulcombe, D. C.

Subjects
*NON-coding RNA, *GENE silencing, *PLANT genetics, *ARABIDOPSIS, *RNA
Abstract

The article focuses on the possible biological roles and mechanisms of small ribonucleic acid (sRNA)-mediated silencing based primarily on the sRNA of plants. It cites the genetic and molecular approaches to determine the sRNAs in Arabidopsis. It examines how sRNAs form interaction cascades and networks affecting genetic and epigenetic systems in growth and development. It assesses the implications of silencing or secondary sRNA production for the potential to form networks of RNA silencing.

Published
2006
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29. RNA Silencing Pathways in Plants.

Author

Herr, A. J. and Baulcombe, D. C.

Subjects
*GENE silencing, *RNA, *PLANT genetics, *PLANTS, *CONFERENCES & conventions, *PLANT viruses
Abstract

Highlights a study which deals with RNA silencing pathways in plants that was presented at the 69th Cold Spring Harbor Symposia on Quantitative Biology in the U.S. in 2004. Molecular analysis of posttranscriptional gene silencing; Information on RNA silencing and susceptibility to plant viruses; Pathways of the silencing.

Published
2004
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30. A wheat α‐Amy2promoter is regulated by gibberellin in transformed oat aleurone protoplasts

Author

Huttly, A. K. and Baulcombe, D. C.

Abstract

Gibberellin (GA3)‐responsive aleurone protoplasts isolated from Avena sativahave been successfully used as a transient expression system to analyse promoter fusions between the wheat α‐amylase gene α‐Amy2/54and the reporter gene GUS. Following PEG‐mediated uptake of plasmid DNA, transient expression directed by the α‐Amy2/54promoter was found to be regulated in the same way as the endogenous oat α‐amylase genes. Expression was thus dependent on the inclusion of GA3in the protoplast incubation media, could not be detected before a lag phase of 2 days following transformation and was inhibited by simultaneous addition of abscisic acid (ABA) with GA3to the media. In contrast, expression from the CaMV 35S promoter in the same system was not affected by GA3or ABA and could be detected 1 day after transformation. Introduction of a further three different promoters into the aleurone protoplasts confirmed that GA3specifically controlled transient expression from the α‐Amy2/54promoter only. Promoter deletions of the α‐Amy2/54: GUS fusion demonstrated that sequences within 300 bp of the start of transcription of the gene were sufficient to direct high‐level expression that was regulated by GA3and ABA.

Published
1989
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31. A gibberellin responsive wheat gene has homology to yeast carboxypeptidase Y.

Author

Baulcombe, D C, Barker, R F, and Jarvis, M G

Abstract

An earlier report (Baulcombe, D. C., and Buffard, D. (1983) Planta 157, 493-501) described the isolation of cDNA clones from mRNAs which are produced in increased amounts when aleurone layers of wheat are treated with gibberellic acid. It is shown here that for one of those cDNAs (2473) the change in level of mRNA in aleurone parallels the change in level of alpha-amylase mRNA. This result was obtained in experiments where the level of gibberellic acid was varied and also when the mRNA was isolated from wheat genotypes which varied in ability to respond to gibberellic acid. In contrast to this, the pattern of 2437 mRNA accumulation in immature grains and in leaf tissue was quite distinct from the pattern of alpha-amylase mRNA accumulation. Analysis of wheat DNA showed that the 2437 mRNA is encoded by a small family of genes located on the short arm of the group 6 chromosomes. One member of this gene family was cloned and sequenced. The coding sequence is interrupted by eight introns and encodes a protein of Mr 55,433. By using hybridization probes from the 5' exon in an S1 nuclease protection assay it was shown that the 2437 mRNA was produced in aleurones (coordinately with alpha-amylase) and in immature grains (not coordinately with alpha-amylase). However, sequence comparison of 1 kilobase of the 5'-flanking region with the sequence of alpha-amylase genes provided no indication of the regulatory elements which would be active in aleurone cells. The protein sequence deduced from the gene sequence has extensive homology with the yeast carboxypeptidase Y, especially in the active site and substrate binding regions. This homology is greater than with the carboxypeptidase I from barley. It is suggested therefore that there are several types of carboxypeptidase encoded in the cereal genome. The sequence of the 2437 protein would represent one of these types and the barley carboxypeptidase I, another.

Published
1987
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39. RNA-directed transcriptional gene silencing in plants can be inherited independently of the RNA trigger and requires Met1 for maintenance.

Author

Jones L, Ratcliff F, and Baulcombe DC

Subjects
Base Sequence, DNA Methylation, DNA Primers, Plant Viruses physiology, RNA Viruses physiology, Nicotiana virology, DNA (Cytosine-5-)-Methyltransferases physiology, Gene Silencing physiology, Plants, Toxic, RNA, Plant physiology, Nicotiana genetics, Transcription, Genetic physiology
Abstract

Background: The association between DNA methylation and gene silencing has long been recognized; however, signals that initiate de novo methylation are largely unknown. In plants, recognition of RNAs that are inducers of posttranscriptional gene silencing (PTGS) can result in sequence-specific DNA methylation, and the aim of this work was to investigate whether heritable epigenetic changes can occur by this mechanism and if the Met1 methyltransferase is required., Results: RNA-directed DNA methylation (RdDM) was initiated in 35S-GFP transgenic plants following infection with plant RNA viruses modified to carry portions of either the 35S promoter or the GFP coding region. Targeting of the promoter sequence resulted in both methylation and transcriptional gene silencing (TGS) that was inherited independently of the RNA trigger. Targeting the coding region also resulted in methylation; however, this was not inherited. Expression of Met1 was suppressed in order to investigate its role in initiation and maintenance of RdDM. Initiation of RdDM was found to be Met1-independent, whereas maintenance of methylation and TGS in the subsequent generations in the absence of the RNA trigger was Met1-dependent. Maintenance of methylation associated with systemic PTGS was also found to be Met1-independent., Conclusions: RNA-triggered events can lead to heritable changes in gene expression, and it is possible that initiation of other epigenetic phenomena such as trans-silencing and paramutation may have an RNA component.

Published
2001
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40. SDE3 encodes an RNA helicase required for post-transcriptional gene silencing in Arabidopsis.

Author

Dalmay T, Horsefield R, Braunstein TH, and Baulcombe DC

Subjects
Amino Acid Sequence, Arabidopsis virology, Chromosome Mapping, Cucumovirus genetics, Cucumovirus pathogenicity, Molecular Sequence Data, Plant Diseases genetics, Plant Proteins genetics, Plant Proteins metabolism, Plant Viruses genetics, Plant Viruses pathogenicity, Plants, Genetically Modified, RNA Helicases metabolism, RNA Viruses genetics, RNA Viruses pathogenicity, RNA, Double-Stranded metabolism, Sequence Analysis, DNA, Sequence Homology, Amino Acid, Arabidopsis genetics, Arabidopsis Proteins, Gene Silencing, RNA Helicases genetics, RNA Processing, Post-Transcriptional
Abstract

Post-transcriptional gene silencing (PTGS) provides protection in plants against virus infection and can suppress expression of transgenes. Arabidopsis plants carrying mutations at the SDE3 locus are defective in PTGS mediated by a green fluorescent protein transgene. However, PTGS mediated by tobacco rattle virus (TRV) was not affected by sde3. From these results we conclude that SDE3, like the previously described RNA polymerase encoded by SDE1, acts at a stage in the mechanism that is circumvented when PTGS is mediated by TRV. The product of SDE3 is similar to RNA helicase-like proteins including GB110 in mouse and other proteins in Drosophila and humans. These proteins are similar to, but clearly distinct from Upf1p and SMG-2, which are required for nonsense-mediated mRNA decay in yeast and Caenorhabditis elegans and, in the case of SMG-2, for PTGS.

Published
2001
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41. Size constraints for targeting post-transcriptional gene silencing and for RNA-directed methylation in Nicotiana benthamiana using a potato virus X vector.

Author

Thomas CL, Jones L, Baulcombe DC, and Maule AJ

Subjects
Green Fluorescent Proteins, Luminescent Proteins metabolism, Transgenes, DNA Methylation, Gene Silencing, Genetic Vectors, Plants, Toxic, Potexvirus genetics, RNA, Plant metabolism, Nicotiana genetics, Transcription, Genetic
Abstract

Using a recombinant potato virus X (PVX) vector, we investigated the relationship between the length of RNA sequence identity with a transgene and the ability to promote post-transcriptional gene silencing (PTGS) and transgene methylation. The lower size limit required for targeting reporter transgene mRNA de novo using PTGS was 23 nucleotides (nt) of complete identity, a size corresponding to that of small RNAs associated with PTGS in plants and RNA interference (RNAi) in animals. The size and sequence specificity were also explored for PTGS-associated transgene methylation and for the targeting of the vector RNA. The PTGS-competent short sequences resulted in similar patterns of methylation. In all cases, including specific sequences of 33 nt with or without symmetrical cytosine residues, the methylation was distributed throughout the transcribed region of the transgene. In contrast, short sequences lacking symmetrical cytosines were less efficient at promoting PTGS of the transgene mRNA. Short gfp sequences in the PVX vector provided as effective a target for the degradation of viral RNA as was found for PVX carrying the complete gfp cDNA. Short sequences were able to initiate PTGS of an endogenous gene, phyotene desaturase, although this occurred in the absence of DNA methylation. This experimental approach provides important insights into the relationship between short RNA sequences and PTGS.

Published
2001
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42. Technical Advance. Tobacco rattle virus as a vector for analysis of gene function by silencing.

Author

Ratcliff F, Martin-Hernandez AM, and Baulcombe DC

Subjects
Base Sequence, DNA, Complementary, Molecular Sequence Data, Gene Silencing, Genetic Vectors, Plant Viruses genetics, RNA Viruses genetics
Abstract

Virus vectors carrying host-derived sequence inserts induce silencing of the corresponding genes in infected plants. This virus-induced gene silencing (VIGS) is a manifestation of an RNA-mediated defence mechanism that is related to post-transcriptional gene silencing (PTGS) in transgenic plants. Here we describe an infectious cDNA clone of tobacco rattle virus (TRV) that has been modified to facilitate insertion of non-viral sequence and subsequent infection to plants. We show that this vector mediates VIGS of endogenous genes in the absence of virus-induced symptoms. Unlike other RNA virus vectors that have been used previously for VIGS, the TRV construct is able to target host RNAs in the growing points of plants. These features indicate that the TRV vector will have wide application for gene discovery in plants.

Published
2001
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43. Molecular biology. Unwinding RNA silencing.

Author

Baulcombe DC

Subjects
Animals, Chlamydomonas enzymology, Genes, RNA metabolism, RNA Processing, Post-Transcriptional, RNA, Double-Stranded metabolism, Retroelements, Transgenes, Chlamydomonas genetics, Gene Silencing, RNA Helicases genetics, RNA Helicases metabolism
Abstract

Eukaryotic cells have developed an elegant system called RNA silencing for getting rid of foreign RNAs whether they be of viral, retrotransposon, or transgene origin. In his Perspective, Baulcombe examines new findings (Wu-Scharf et al.) showing that in a green alga the gene responsible for RNA silencing encodes an RNA helicase (related to proteins in worms and other organisms) that is required for regulation of gene expression at the RNA level.

Published
2000
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44. A viral movement protein prevents spread of the gene silencing signal in Nicotiana benthamiana.

Author

Voinnet O, Lederer C, and Baulcombe DC

Subjects
Gene Deletion, Gene Expression Regulation, Plant physiology, Gene Expression Regulation, Viral physiology, Mutation genetics, Plant Viral Movement Proteins, Plants, Genetically Modified metabolism, Plants, Genetically Modified virology, Potexvirus genetics, Potexvirus metabolism, RNA Processing, Post-Transcriptional genetics, RNA, Plant genetics, RNA, Plant metabolism, RNA, Viral genetics, RNA, Viral metabolism, Nicotiana metabolism, Nicotiana virology, Transgenes genetics, Viral Proteins metabolism, Gene Silencing physiology, Plants, Genetically Modified genetics, Plants, Toxic, Nicotiana genetics, Viral Proteins genetics
Abstract

In plants, viruses induce an RNA-mediated defense that is similar to posttranscriptional gene silencing (PTGS) of transgenes. Here we demonstrate with potato virus X (PVX) that PTGS operates as a systemic, sequence-specific defense system. However, in grafting experiments or with movement defective forms of PVX, we could not detect systemic silencing unless the 25 kDa viral movement protein (p25) was made nonfunctional. Investigation of p25 revealed two branches to the PTGS pathway that converge in the production of 25 nucleotide RNAs corresponding to the target RNA. One of these branches is unique to virus-induced PTGS and is not affected by p25. The second branch is common to both virus- and transgene-induced PTGS, is blocked by p25, and is likely to generate the systemic silencing signal.

Published
2000
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45. Homologues of a single resistance-gene cluster in potato confer resistance to distinct pathogens: a virus and a nematode.

Author

van der Vossen EA, van der Voort JN, Kanyuka K, Bendahmane A, Sandbrink H, Baulcombe DC, Bakker J, Stiekema WJ, and Klein-Lankhorst RM

Subjects
Amino Acid Sequence, Animals, Base Sequence, DNA Primers, Genetic Complementation Test, Molecular Sequence Data, Nucleotides genetics, Plant Proteins chemistry, Sequence Homology, Amino Acid, Solanum tuberosum parasitology, Solanum tuberosum virology, Multigene Family, Nematoda pathogenicity, Plant Proteins genetics, Plant Viruses pathogenicity, Solanum tuberosum genetics
Abstract

The isolation of the nematode-resistance gene Gpa2 in potato is described, and it is demonstrated that highly homologous resistance genes of a single resistance-gene cluster can confer resistance to distinct pathogen species. Molecular analysis of the Gpa2 locus resulted in the identification of an R-gene cluster of four highly homologous genes in a region of approximately 115 kb. At least two of these genes are active: one corresponds to the previously isolated Rx1 gene that confers resistance to potato virus X, while the other corresponds to the Gpa2 gene that confers resistance to the potato cyst nematode Globodera pallida. The proteins encoded by the Gpa2 and the Rx1 genes share an overall homology of over 88% (amino-acid identity) and belong to the leucine-zipper, nucleotide-binding site, leucine-rich repeat (LZ-NBS-LRR)-containing class of plant resistance genes. From the sequence conservation between Gpa2 and Rx1 it is clear that there is a direct evolutionary relationship between the two proteins. Sequence diversity is concentrated in the LRR region and in the C-terminus. The putative effector domains are more conserved suggesting that, at least in this case, nematode and virus resistance cascades could share common components. These findings underline the potential of protein breeding for engineering new resistance specificities against plant pathogens in vitro.

Published
2000
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46. An Ry-mediated resistance response in potato requires the intact active site of the NIa proteinase from potato virus Y.

Author

Mestre P, Brigneti G, and Baulcombe DC

Subjects
Amino Acid Sequence, Base Sequence, Binding Sites, DNA Primers, Endopeptidases, Molecular Sequence Data, Mutation, Potyvirus pathogenicity, Sequence Homology, Amino Acid, Viral Proteins chemistry, Viral Proteins genetics, Virulence, Genes, Plant, Potyvirus enzymology, Solanum tuberosum immunology, Viral Proteins metabolism
Abstract

Ry confers extreme resistance to all strains of potato virus Y (PVY). To identify the elicitor of the Ry-mediated resistance against PVY in potato, we expressed each of the PVY-encoded proteins in leaves of PVY-resistant (Ry) and -susceptible (ry) plants. For most of the proteins tested, there was no evident response. However, when the NIa proteinase was expressed in leaves of Ry plants, there was a hypersensitive response (HR). Proteinase active site mutants failed to induce the Ry-mediated response. The HR was also induced by the NIa proteinase from pepper mottle virus (PepMoV), which has the same cleavage specificity as the PVY enzyme, but not by the tobacco etch virus (TEV) or the potato virus A (PVA) proteinases that cleave different peptide motifs. Based on these results, we propose that Ry-mediated resistance requires the intact active site of the NIa proteinase. Although the structure of the active proteinase could have elicitor activity, it is possible that this proteinase releases an elicitor by cleavage of a host-encoded protein. Alternatively, the proteinase could inactivate a negative regulator of the Ry-mediated resistance response.

Published
2000
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47. Cell-to-cell movement of the 25K protein of potato virus X is regulated by three other viral proteins.

Author

Yang Y, Ding B, Baulcombe DC, and Verchot J

Subjects
Biological Transport, Capsid chemistry, Capsid genetics, Cell Compartmentation, Cell Membrane metabolism, Genes, Reporter, Green Fluorescent Proteins, Luminescent Proteins genetics, Luminescent Proteins metabolism, Microscopy, Fluorescence, Molecular Weight, Plants, Genetically Modified, Potexvirus genetics, Recombinant Fusion Proteins chemistry, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Nicotiana genetics, Viral Proteins chemistry, Viral Proteins genetics, Capsid metabolism, Capsid Proteins, Plants, Toxic, Potexvirus metabolism, Nicotiana virology, Viral Proteins metabolism
Abstract

The 25K, 12K, and 8K proteins and coat protein (CP) of Potato virus X (PVX) are required for virus cell-to-cell movement. In this study, experiments were conducted to determine whether the PVX 25K protein moves cell to cell and to explore potential interactions between the PVX 25K, 12K, and 8K proteins and CP. The PVX 25K gene was fused to the green fluorescent protein (GFP) gene and inserted into plasmids adjacent to the cauliflower mosaic virus 35S promoter. These plasmids were introduced by biolistic bombardment to transgenic tobacco expressing the PVX 12K, 8K, and CP genes. The GFP:25K fused proteins moved cell to cell on nontransgenic tobacco and tobacco expressing either the 12K or 8K proteins. However, the GFP:25K proteins did not move on transgenic tobacco expressing the combined 12K/8K genes or the CP gene. Thus, movement of the PVX 25K protein through plasmodesmata may be regulated by interactions with other PVX proteins.

Published
2000
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48. An RNA-dependent RNA polymerase gene in Arabidopsis is required for posttranscriptional gene silencing mediated by a transgene but not by a virus.

Author

Dalmay T, Hamilton A, Rudd S, Angell S, and Baulcombe DC

Subjects
Amino Acid Sequence, Arabidopsis genetics, Base Sequence, DNA Methylation, Molecular Sequence Data, Mutagenesis, Neurospora crassa enzymology, Plants, Genetically Modified, Sequence Homology, Amino Acid, Tobacco Mosaic Virus genetics, Arabidopsis enzymology, Fungal Proteins, Gene Silencing, RNA Processing, Post-Transcriptional, RNA-Dependent RNA Polymerase genetics, Transgenes
Abstract

Posttranscriptional gene silencing is a defense mechanism in plants that is similar to quelling in fungi and RNA interference in animals. Here, we describe four genetic loci that are required for posttranscriptional gene silencing in Arabidopsis. One of these, SDE1, is a plant homolog of QDE-1 in Neurospora crassa that encodes an RNA-dependent RNA polymerase. The sde1 mutation was specific for posttranscriptional gene silencing induced by transgenes rather than by viruses. We propose that the role of SDE1 is to synthesize a double-stranded RNA initiator of posttranscriptional gene silencing. According to this idea, when a virus induces posttranscriptional gene silencing, the virus-encoded RNA polymerase would produce the double-stranded RNA and SDE1 would be redundant.

Published
2000
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49. Virus-induced silencing of a plant cellulose synthase gene.

Author

Burton RA, Gibeaut DM, Bacic A, Findlay K, Roberts K, Hamilton A, Baulcombe DC, and Fincher GB

Subjects
Base Sequence, DNA, Complementary, Esterification, Glucosyltransferases metabolism, Microscopy, Electron, Scanning, Molecular Sequence Data, Phenotype, Polysaccharides metabolism, Sequence Homology, Nucleic Acid, Nicotiana genetics, Nicotiana ultrastructure, Transcription, Genetic, Gene Silencing, Glucosyltransferases genetics, Plants, Toxic, Nicotiana enzymology
Abstract

Specific cDNA fragments corresponding to putative cellulose synthase genes (CesA) were inserted into potato virus X vectors for functional analysis in Nicotiana benthamiana by using virus-induced gene silencing. Plants infected with one group of cDNAs had much shorter internode lengths, small leaves, and a "dwarf" phenotype. Consistent with a loss of cell wall cellulose, abnormally large and in many cases spherical cells ballooned from the undersurfaces of leaves, particularly in regions adjacent to vascular tissues. Linkage analyses of wall polysaccharides prepared from infected leaves revealed a 25% decrease in cellulose content. Transcript levels for at least one member of the CesA cellulose synthase gene family were lower in infected plants. The decrease in cellulose content in cell walls was offset by an increase in homogalacturonan, in which the degree of esterification of carboxyl groups decreased from approximately 50 to approximately 33%. The results suggest that feedback loops interconnect the cellular machinery controlling cellulose and pectin biosynthesis. On the basis of the phenotypic features of the infected plants, changes in wall composition, and the reduced abundance of CesA mRNA, we concluded that the cDNA fragments silenced one or more cellulose synthase genes.

Published
2000
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50. Potato virus X amplicons in arabidopsis mediate genetic and epigenetic gene silencing.

Author

Dalmay T, Hamilton A, Mueller E, and Baulcombe DC

Subjects
Arabidopsis virology, DNA Methylation, Gene Expression Regulation, Plant, Green Fluorescent Proteins, Luminescent Proteins genetics, Luminescent Proteins metabolism, Plants, Genetically Modified, Potexvirus growth & development, RNA, Plant genetics, RNA, Plant physiology, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Transgenes, Virus Replication genetics, Arabidopsis genetics, Gene Silencing, Genes, Viral genetics, Potexvirus genetics
Abstract

Amplicon transgenes from potato virus X (PVX) are based on a modified version of the viral genome and are efficient activators of post-transcriptional gene silencing (PTGS). To determine whether PVX amplicons activate PTGS in Arabidopsis, we used constructs based on the genome of PVX carrying a green fluorescent protein (GFP) reporter gene. Our analysis of the transgene phenotype exploited previous observations indicating that PTGS is associated with short 25-nucleotide RNA species, transgene methylation, and homology-dependent virus resistance. We also used the ability of turnip mosaic virus to suppress gene silencing as a means of dissecting stages of the mechanism. The results showed that a PVX:GFP amplicon induces weak PTGS and that this PTGS was enhanced in the presence of a GFP reporter gene. Our interpretation of these data is that the PTGS induced by the amplicon was genetically determined and equivalent to the initiation stage of the PTGS mechanism. The PTGS induced by the combined amplicon and reporter gene was equivalent to the maintenance stage and was associated with an epigenetic conversion of the transgene. The distinction between genetic and epigenetic PTGS explains the well-characterized effects of transgene dosage on PTGS that have been previously interpreted in terms of RNA expression thresholds.

Published
2000
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