Plant epigenetics and RNA silencing
My long-term interest is epigenetic modifications and their role in determination. As a graduate student at Rockefeller University, I decided to work on plants because it was possible to distinguish between epigenetic changes and genetic mutations by genetic analysis of plants regenerated from individual somatic cells. I am particularly fond of work started in the 1970's at Princeton University and the University of Illinois-Urbana that established the existence of cell-heritable determination in plants, overturned the commonly accepted idea that plant cells "forget" their determined state in culture, and led to a mathematical framework for estimating cellular variation rates in tissues. Later we showed certain cultured cells also undergo exceeding rapid epigenetic changes that are then inherited as a Mendelian trait. These findings suggested a plausible explanation for the extreme plasticity of determination in plants and showed that certain epigenetic states in production of growth factors can be transmitted to the next sexual generation.
The 1980s were the start of an exciting period at FMI. The groups of Ingo Potrykus, Barbara Hohn, and Thomas Hohn made pioneering advances in the area of plant genetic transformation. My group focussed on the function of chitinases and Beta-1,3-glucanases in plant innate immunity. Our collaborations with Thomas Boller, who later joined the FMI, and the Ciba-Geigy/ Novartis plant pathology groups led to influential contributions relevant to the evolution of plant gene families, intracellular transport and targeting of proteins, pathogenesis-related signalling pathways, and the function of Beta-1,3-glucanases in viral pathogenesis, cell-to-cell communication, and seed germination.
My interest returned to epigenetics in the late 1980s when we and several other groups discovered what is now called RNA interference (RNAi) in transgenic plants. We discovered that RNAi in plants is an epigenetic form of RNA degradation that persists during somatic development and is transmitted through meiosis. We proposed that this type of epigenetic silencing is maintained by self-sustained production of a sequence-specific "silencing activator" above a critical threshold concentration. Strong support for this threshhold hypothesis came from our finding that siRNAs introduced into cells trigger sustained production of secondary siRNAs from the same target. Rapid progress –particularly after the first small RNAs were cloned in 2000– has established the importance of RNA-silencing in animals and the presence in plants of silencing networks with shared components and overlapping functions. Our most recent work deals with the organization of these networks and the function of microRNAs. For details on this and our earlier work follow the link to "List of Publications".
I retired from FMI in May 2007 after 27 years of continuous support by Ciba-Geigy and then the Novartis Research Foundation. Their blind faith and the remarkable atmosphere, exceptional academic freedom, and resources they provided at FMI allowed me to explore uncharted areas and tackle challenging research problems. I'm particularly proud that many young, talented scientists associated with my group over the years have gone on to establish their own research groups and make important scientific contributions. As an emeritus member, I plan to continue teaching, helping young people, and exploring the "epigenetic landscape" - but with a bit more time to enjoy grandchildren. For a more personal account of my work and the people involved, follow the link to SCIENTIFIC AUTOBIOGRAPHY.
Chrispeels,M.J. and Meins,F.J. (2014) Armin Braun- A Biographical Memoir of the National Academy of SciencesWashington: National Academy of Sciences Press, pp. 1-25
Si-Ammour,A., Windels,D., Arn-Bouldoires,E., Kutter,C., Ailhas,J., Meins,F., and Vazquez,F. (2011) miR393 and Secondary siRNAs Regulate Expression of the TIR1/AFB2 Auxin Receptor Clade and Auxin-Related Development of Arabidopsis LeavesPlant Physiol. 157, 683-691
Blevins T, Rajeswaran R, Aregger M, Borah BK, Schepetilnikov M, Baerlocher L, Farinelli L, Meins F Jr, Hohn T, Pooggin MM (2011) Massive production of small RNAs from a non-coding region of Cauliflower mosaic virus in plant defense and viral counter-defense.Nucleic Acids Res. 39:5003-5014
Blevins T, Pontes O, Pikaard CS, Meins F Jr. (2009) Heterochromatic siRNAs and DDM1 independently silence aberrant 5S rDNA transcripts in ArabidopsisPLoS One. 2009 Jun 16;4(6):e5932
Vazquez F, Blevins T, Ailhas J, Boller T, Meins F Jr (2008) Evolution of Arabidopsis MIR genes generates novel microRNA classesNucl Acids Res 36: 6429-6438
Kutter C, Schob H, Stadler M, Meins F Jr, Si-Ammour A (2007) MicroRNA-mediated regulation of stomatal development in ArabidopsisPlant Cell 19:2417-2429
Blevins T, Rajeswaran R, Shivaprasad PV, Beknazariants D, Si-Ammour A, Park HS, Vazquez F, Robertson D, Meins F Jr, Hohn T, Pooggin MM (2006) Four plant Dicers mediate viral small RNA biogenesis and DNA virus induced silencingNucl Acids Res 34:6233-6246
Meins F Jr, Thomas M (2003) Meiotic transmission of epigenetic changes in the cell-division factor requirement of plant cellsDevelopment 130:6201-6208
Klahre U, Crété P, Leuenberger SA, Iglesias VA, Meins F (2002) High molecular weight RNAs and small interfering RNAs induce systemic posttranscriptional gene silencing in plantsProc Natl Acad Sci USA 99:11981-11986
Di Serio F, Schöb H, Iglesias A, Tarina C,Bouldoires E, Meins F Jr (2001) Sense and antisense-mediated gene silencing in tobacco is inhibited by the same viral suppressors and is associated with accumulation of small RNAsProc Natl Acad Sci USA 98:6506-6510
Bucher GL, Tarina C, Heinlein M, Di Serio F,Meins F Jr, Iglesias A (2001) Local expression of enzymatically active class I beta-13-glucanase enhances symptoms of TMVinfection in tobaccoPlant J 28:361-369
Meins F Jr (1996) Epigenetic modifications and gene silencing in plants In: Russo VEA, Martienssen RA, Riggs AD (eds) Epigenetic mechanisms of gene regulationCold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., pp 415-442
Kunz C, Schöb H, Stam M, Kooter JM, Meins F Jr (1996) Developmentally regulated silencing and reactivation of tobacco chitinase transgene expressionPlant J 10:437-450
Beffa R, Szell M, Meuwly P, Pay A, Vögeli-Lange R, Métraux J-P, Neuhaus G, Meins F Jr, Nagy F (1995) Cholera toxin elevates pathogen resistance and induces pathogenesis-related gene expression in tobaccoEMBO J 14:5753-5761
Hart CM, Nagy F, Meins F Jr (1993) A 61 bp enhancer element of the tobacco beta-1,3-glucanase B gene interacts with one or more regulated nuclear proteinsPlant Mol Biol 21:121-131
Beffa RS, Neuhaus J-M, Meins F Jr (1993) Physiological compensation in antisense transformants: Specific induction of an ersatz glucan endo-1,3-beta-glucosidase in plants infected with necrotizing virusesProc Natl Acad Sci USA 90:8792-8796
Sticher L, Hofsteenge J, Milani A, Neuhaus J-M, Meins F Jr (1992) Vacuolar chitinases of tobacco: A new class of hydroxyproline-containing proteinsScience 257:655-657
Neuhaus J-M, Sticher L, Meins F Jr, Boller T (1991) A short C-terminal sequence necessary and sufficient for the targeting of chitinases to the plant vacuoleProc Natl Acad Sci USA 88:10362-10366
Shinshi H, Wenzler H, Neuhaus JM, Felix G, Hofsteenge J, Meins F Jr (1988) Evidence for N- and C-terminal processing of a plant defense- related enzyme. Primary structure of tobacco prepro-beta- 1,3-glucanaseProc Natl Acad Sci USA 85:5541-5545
Shinshi H, Mohnen D, Meins F Jr (1987) Regulation of a plant pathogenesis-related enzyme: Inhibition of chitinase and chitinase mRNA accumulation in cultured tobacco tissues by auxin and cytokininProc Natl Acad Sci USA 84:89-93
Hansen CE, Meins F Jr (1986) Evidence for a cellular gene with potential oncogenic activity in plantsProc Natl Acad Sci USA 83:2492-2495
Pengelly W, Meins F Jr (1977) A specific radio-immunoassay for nanogram quantities of the auxin, indole-3-acetic acidPlanta 136:173-180
Binns A, Meins F Jr (1973) Habituation of tobacco pith cells for factors promoting cell division is heritable and potentially reversibleProc Natl Acad Sci USA 70:2660-2662