caa a22 4500 467895252 CHVBK 20180406152801.0 cr unu---uuuuu 170328e20060901xx s 000 0 eng 10.1007/s11103-006-9000-7 doi (NATIONALLICENCE)springer-10.1007/s11103-006-9000-7 Nature of stress and transgene locus influences transgene expression stability in barley [Elektronische Daten] [Ling Meng, Meira Ziv, Peggy Lemaux] Stress and the nature of the transgene locus can affect transgene expression stability. These effects were studied in two, stably expressing, T6 populations of barley (Hordeum vulgare): bombardment-mediated, multi-copy lines with ubiquitin-driven bar and uidA or single-copy lines from Ds-mediated gene delivery with ubiquitin-driven bar alone. Imposing the environmental stresses, water and nutrient deprivation and heat shock, did not reproducibly affect transgene expression stability; however, high frequencies of heritable transcriptional gene silencing (TGS) occurred following in vitro culture after six generations of stable expression in the multi-copy subline, T3#30, but not in the other lines studied. T3#30 plants with complete TGS had epigenetic modification patterns exactly like those in an identical sibling subline, T3#31, which had significant reduction in transgene expression in the T3 generation and was completely transcriptionally silenced in the absence of imposed stresses in the T6 generation. Complete TGS in T3#30 plants correlated with methylation in the 5′UTR and intron of the ubi1 promoter complex and condensation of chromatin around the transgenes; DNA methylation likely occurred prior to chromatin condensation. Partial TGS in T3#30 also correlated with methylation of the ubi1 promoter complex, as occurred with complete TGS. T3#30 has a complex transgene structure with inverted repeat transgene fragments and a 3′-LTR from a barley retrotransposon, and therefore the transgene locus itself may affect its tendency to silence after in vitro culture and transgene silencing might result from host defense mechanisms activated by changes in plant developmental programming and/or stresses imposed during in vitro growth. Springer Science+Business Media B.V., 2006 Barley nationallicence Chromatin condensation nationallicence Environmental stress nationallicence In vitro culture nationallicence DNA methylation nationallicence Transgene silencing nationallicence 2,4-D : 2,4-dichlorophenoxyacetic acid nationallicence BAP : 6-benzylaminopurine nationallicence IBA : indole butyric acid nationallicence MS : Murishige and Skoog nationallicence RWC : relative water content nationallicence Meng Ling Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, 94720, Berkeley, CA, USA aut Ziv Meira Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, 94720, Berkeley, CA, USA aut Lemaux Peggy Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, 94720, Berkeley, CA, USA aut Plant Molecular Biology Kluwer Academic Publishers 62/1-2(2006-09-01), 15-28 0167-4412 62:1-2<15 2006 62 11103 https://doi.org/10.1007/s11103-006-9000-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11103-006-9000-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Meng Ling Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Ziv Meira Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Lemaux Peggy Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, 94720, Berkeley, CA, USA aut NATIONALLICENCE 773 0- Plant Molecular Biology Kluwer Academic Publishers 62/1-2(2006-09-01), 15-28 0167-4412 62:1-2<15 2006 62 11103 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer