Abstract
We tested the efficacy of an attenuation system developed to preclude the deleterious effects of floral promoter::cytotoxin genes on vegetative growth of transgenic sterile plants. We tested the promoter (2.6 kb 5′ region) of the poplar LEAFY gene PTLF driving barstar, combined on the same T-DNA with barstar driven by either the CaMV 35S basal promoter +5 to −72 fragment (35SBP), 35SBP fused to the TMV omega element (35SBP omega), or the NOS promoter. The unattenuated pPTLF::barnase construct failed to give rise to any transgenic events, suggesting substantial non-reproductive expression from this promoter. The barstar-attenuated constructs enabled transformation, but the rate was reduced by nearly one-third. Four events (7% of attenuated events) had highly abnormal morphology, and were identified during the early phases of propagation; these events had significantly higher barnase:barstar expression ratios based on quantitative RT-PCR. A greenhouse study showed that phenotypically normal attenuated plants grew at the same rate as wild-type and barnase-lacking transgenic plants. A statistically significant positive linear association was found between relative growth rate (RGR) and barstar:barnase ratio in the attenuated events, and graphical analysis suggested a threshold for barstar attenuation of barnase, above which additional levels of barstar did not provide further attenuation. Surprisingly, the appearance and growth rate of the nearly all of the attenuated events were substantially reduced after one or two growing seasons in the field, and the extent of growth reduction was associated with barstar:barnase expression ratio. These results demonstrate the importance of field testing during early phases of research to identify pleiotropic effects of transgenic sterility genes in trees.
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Allen GC, Hall G Jr, Michalowski G, Newman W, Spiker S, Weissinger AK, Thompson WF (1996) High-level transgene expression in plant cells: effects of a strong scaffold attachment region from tobacco. Plant Cell 8:899–913
Allen GC, Spiker S, Thompson WF (2000) Use of matrix attachment regions (MARs) to minimize transgene silencing. Plant Mol Biol 43:361–376
Beals TP, Goldberg RB (1997) A novel cell ablation strategy blocks tobacco anther dehiscence. Plant Cell 9:1527–1545
Bhalero R, Nilsson O, Sandberg G (2003) Out of the woods: forest biotechnology enters the genomic era. Curr Opin Biotechnol 14:206–213
Bi YM, Rothstein SJ, Wildeman AG (2001) A novel strategy for regulated expression of a cytotoxic gene. Gene 279:175–179
Block M, Debrouwer D (1993) Engineered fertility control in transgenic Brassica napus L.: histochemical analysis of anther development. Planta 189:218–225
Block M, Debrouwer D, Moens T (1997) The development of a nuclear male sterility system in wheat. Expression of the barnase gene under the control of tapetum specific promoters. Theor Appl Genet 95:125–131
Boerjan W (2005) Biotechnology and the domestication of forest trees. Curr Opin Biotechnol 16:159–166
Brunner AM, Rottmann WH, Sheppard LA, Krutovskii K, DiFazio SP, Leonardi S, Strauss SH (2000) Structure and expression of duplicate AGAMOUS orthologues in poplar. Plant Mol Biol 44:619–634
Brunner A, Li J, DiFazio SP, Shevchenko O, Montgomery B, Mohamed R, Wei H, Ma C, Elias A, Van Wormer K, Strauss SH (2006) Genetic containment of forest plantations. Tree Genet Genomes (in press)
Brunner AM, Yakovlev IA, Strauss SH (2004) Validating internal controls for quantitative plant gene expression studies. BioMed Central Plant Biology 4:14. DOI:10.1186/1471-2229-4-14
Burgess DG, Ralston EJ, Hanson WG, Heckert M, Ho M, Jenq T, Palys JM, Tang K, Gutterson N (2002) A novel, two-component system for cell lethality and its use in engineering nuclear male-sterility in plants. Plant J 31:113–125
Filichkin SA, Meilan R, Busov VB, Ma C, Brunner AM, Strauss SH (2006) Alcohol-inducible gene expression in transgenic Populus. Plant Cell Rep 25:660–667
Goldman MH, Goldberg RB, Mariani C (1994) Female sterile tobacco plants are produced by stigma-specific cell ablation. EMBO J 13:2976–2984
Han KH, Ma C, Strauss SH (1997) Matrix attachment regions (MARs) enhance transformation frequency and transgene expression in poplar. Transgenic Res 6:415–420
Hartley RW (1988) Barnase and barstar: expression of its cloned inhibitor permits expression of a cloned ribonuclease. J Mol Biol 202:913–915
Hellens RP, Edwards EA, Leyland NR, Bean S, Mullineaus PM (2000) pGreen: a versatile and flexible binary Ti vector for Agrobacterium-mediated plant transformation. Plant Mol Biol 42:819–832
Höfig KP, Möller R, Donaldson L, Putterill J, Walter C (2006) Towards male-sterility in Pinus radiata – a stilbene synthase approach to genetically engineer nuclear male sterility. Plant Biotechnol J 4:333–343
Holsters M, de Waele D, Depicker A, Messens E, Montagu MV, Schell J (1978) Transfection and transformations of Agrobacterium tumefaciens. Mol Gen Genet 163:181–187
James R, DiFazio S, Brunner A, Strauss SH (1998) Environmental effects of genetically engineered woody biomass crops. Biomass Bioenerg 14:403–414
Kyozuka J, Harcourt R, Peacock WJ, Dennis ES (1997) Eucalyptus has functional equivalents of the Arabidopsis AP1 gene. Plant Mol Biol 35:573–584
Lemmetyinen J, Sopanen T (2004a) Modification of flowering in forest trees. In: Kumar S, Fladung M (eds) Molecular genetics and breeding of forest trees. Haworth Press Inc., NY, pp 263–292
Lemmetyinen J, Sopanen T (2004b) Prevention of the flowering of a tree, silver birch. Mol Breeding 13:243–249
Leuchtenberger S, Perz A, Gatz C, Bartsch JW (2001) Conditional cell ablation by stringent tetracycline-dependent regulation of barnase in mammalian cells. Nucleic Acids Res 29:1–6
Mariani C, Beuckeleer MD, Truettner J, Leemans J, Goldberg RB (1990) Induction of male sterility in plants by a chimaeric ribonuclease gene. Nature 347:737–741
Mariani C, Gossele V, Beuckeleer MD, Block MD, Goldberg RB, Greef WD, Leemans J (1992) A chimaeric ribonuclease-inhibitor gene restores fertility to male sterile plants. Nature 357:384–387
Meilan R, Ellis D, Pilate G, Brunner AM, Skinner J (2004) Accomplishments and challenges in genetic engineering of forest trees. In: Strauss SH, Bradshaw HD (eds) The bioengineered forest: challenges to science and society. Resources for the Future, Washington, DC, pp 36–51
Merkle SA, Dean JFD (2000) Forest tree biotechnology. Curr Opin Biotechnol 11:298–302
Nilsson O, Wu E, Wolfe DS, Weigel D (1998) Genetic ablation of flowers in transgenic Arabidopsis. Plant J 15:799–804
Paddon CJ, Hartley RW (1986) Cloning, sequencing and transcription of an inactivated copy of Bacillus amyloliquefaciens extracellular ribonuclease (barnase). Gene 40:231–239
Paddon CJ, Hartley RW (1987) Expression of Bacillus amyloliquefaciens extracellular ribonuclease (barnase) in Escherichia coli following an inactivating mutation. Gene 53:11–19
Peña L, Séguin A (2001) Recent advances in genetic transformation of trees. Trends Biotechnol 19:500–506
Rottmann WH, Meilan R, Sheppard LA, Brunner AM, Skinner JS, Ma C, Cheng S, Jouanin L, Pilate G, Strauss SH (2000) Diverse effects of over expression of LEAFY and PTLF, a poplar (Populus) homolog of LEAFY/FLOICAULA, in transgenic poplar and Arabidopsis. Plant J 22:235–245
Skinner JS, Meilan R, Brunner AM, Strauss SH (2000) Options for genetic engineering of floral sterility in forest trees. In: Jain SM, Minocha SC (eds) Molecular biology of woody plants. Kluwer Academic Pubishers, Dordrecht, The Netherlands, pp 135–153
Skinner JS, Meilan R, Ma C, Strauss SH (2003) The Populus PTD promoter imparts floral-predominant expression and enables high levels of floral–organ ablation in Populus, Nicotiana, and Arabidopsis. Mol Breed 12:119–132
Southerton SG, Strauss SH, Olive MR, Harcourt RL, Decroocq V, Zhu X, Llewellyn DJ, Peacock WJ, Dennis ES (1998a) Eucalyptus has a functional equivalent of the Arabidopsis floral meristem identity gene LEAFY. Plant Mol Biol 37:897–910
Southerton SG, Marshall H, Mouradov A, Teasdale RD (1998b) Eucalypt MADS-box genes expressed in developing flowers. Plant Physiol 118:365–372
Strauss SH, Rottmann WH, Brunner AM, Sheppard LA (1995) Genetic engineering of reproductive sterility in forest trees. Mol Breed 1:5–26
Strauss SH, DiFazio SP, Meilan R (2001) Genetically modified poplars in context. Forest Chron 77:271–279
Valenzuela S, Strauss SH (2005) Lost in the woods. Nature Biotechnol 23:532–533
Velten J, Schell J (1985) Selection-expression plasmid vectors for use in genetic transformation of higher plants. Nucleic Acids Res 13:6981–6998
Walter C, Fenning T (2004) Deployment of genetically-engineered trees in plantation forestry – An issue of concern? In: Plantation forestry biotechnology for the 21st century. Research Signpost, Kerala, India, pp 423–446
Wei H, Meilan R, Brunner AM, Skinner JS, Ma C, Strauss SH (2006) Transgenic sterility in Populus: expression properties of the poplar PTLF, Agrobacterium NOS, and two minimal 35S promoters in vegetative tissues. Tree Physiol 26:401–410
Weigel D et al (19 authors) (2000) Activation tagging in Arabidopsis. Plant Physiol 122:1003–1014
Yoo WY, Bomblies K, Yoo SK, Yang JW, Choi MS, Lee JS, Weigel D, Ahn JH (2005) The 35S promoter used in a selectable marker gene of a plant transformation vector affect the expression of the transgene. Planta 221:523–530
Acknowledgements
We are grateful to Jace Carson, Edward Leber, and Elizabeth Jaeger for their technical assistance. We also thank the Consortium for Plant Biotechnology Research, Inc. (agreement GO12026-157); the US Department of Energy’s Biomass Program [through contract #85X-ST807V with Oak Ridge National Laboratory (managed by UT-Battelle, LLC, for the US Department of Energy under contract DE-AC05-00OR22725)]; and companies supporting the Tree Genomics and Biosafety Research Consortium, based at Oregon State University, for their financial support.
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Wei, H., Meilan, R., Brunner, A.M. et al. Field trial detects incomplete barstar attenuation of vegetative cytotoxicity in Populus trees containing a poplar LEAFY promoter::barnase sterility transgene. Mol Breeding 19, 69–85 (2007). https://doi.org/10.1007/s11032-006-9045-y
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DOI: https://doi.org/10.1007/s11032-006-9045-y