Genomic stability and long-term transgene expression in poplar
- 399 Downloads
Stable expression of foreign genes over the entire life span of a plant is important for long-lived organisms such as trees. For transgenic forest trees, very little information is available on long-term transgene expression and genomic stability. Independent transgenic lines obtained directly after transformation are initially screened in respect to T-DNA integration and transgene expression. However, very little consideration has been given to long-term transgene stability in long-lived forest trees. We have investigated possible genome wide changes following T-DNA integration as well as long-term stability of transgene expression in different transgenic lines of hybrid aspen (Populus tremula × Populus tremuloides) that are up to 19 years old. For studies on possible genome wide changes following T-DNA integration, four different independent rolC-transgenic lines were subjected to an extensive AFLP study and compared to the non-transgenic control line. Only minor genomic changes following T-DNA integration could be detected. To study long-term transgene expression, six different independent rolC-transgenic lines produced in 1993 and since that time have been kept continuously under in vitro conditions. In addition, 18 transgenic plants belonging to eight independent rolC-transgenic lines transferred to glasshouse between 1994 and 2004 were chosen to determine the presence and expression of the rolC gene. In all transgenic lines examined, the rolC gene could successfully be amplified by PCR tests. Both, the 19 years old tissue cultures and the up to 18 years old glasshouse-grown trees revealed expression of the rolC transgene, as demonstrated by the rolC-phenotype and/or northern blot experiments confirming long-term transgene expression.
KeywordsGenomic changes Genetic transformation Transgene insertion Transgene stability Transgenic trees
This study was supported by the Federal Ministry for Education and Research (BMBF). We deeply thank Dr. Trevor Fenning (Northern Research Station of Forest Research, Roslin, UK) for critically reading the manuscript. The technical assistance of Olaf Polak, Doris Ebbinghaus and Anke Schellhorn is gratefully acknowledged.
- Anand A, Trick HN, Gill BS, Muthukrishnan S (2003) Stable transgene expression and random gene silencing in wheat. Plant Biotech J 1:241–251Google Scholar
- Fladung M, Muhs HJ, Ahuja MR (1996) Morphological changes in transgenic Populus carrying the rolC gene from Agrobacterium rhizogenes. Silv Genet 45:349–354Google Scholar
- Li J, Meilan R, Ma C, Barish M, Strauss SH (2008b) Stability of herbicide resistance over 8 years of coppice in field-grown, genetically engineered poplars. West J Appl For 23:89–93Google Scholar
- Markussen T, Tusch A, Stephan BR, Fladung M (2004) Identification of molecular markers for selected wood properties of Norway spruce Picea abies L. (Karst.) I. Wood density. Silv Genet 53:45–50Google Scholar
- Meilan R, Auerbach DJ, Ma C, DiFazio SP, Strauss SH (2002) Stability of herbicide resistance and GUS expression in transgenic hybrid poplars (Populus sp.) during four years of field trials and vegetative propagation. HortScience 37:277–280Google Scholar
- Mirza B (2005) Influence of the nature of the T-DNA insertion region on transgene expression in Arabidopsis thaliana. Genetika 411601–411607Google Scholar
- Pons E, Peris JE, Peña L (2012) Field performance of transgenic citrus trees: assessment of the long-term expression of uidA and nptII transgenes and its impact on relevant agronomic and phenotypic characteristics. BMC Biotechnol 12–41Google Scholar
- Zeng FS, Xin Y, Li B, Zhan YG, Yang CP (2011) The stability of transgene expression and effect of DNA methylation on post transcriptional gene silencing (PTGS) in birch. Afr J Biotech 10:8188–8193Google Scholar