title: Transgene expression and transgene-induced silencing in diploid and autotetraploid Arabidopsis.
abstract: Previous studies have suggested that transgene expression in plants can be affected by ploidy. Here we show that three different transgenes, a reporter transgene, an antisense transgene, and a hairpin RNA (hpRNA) transgene, are all expressed at a lower level in autotetraploid (4n) than in diploid (2n) Arabidopsis. RNA silencing of two endogenous genes was induced by the antisense and hpRNA transgenes and this silencing is significantly less effective in 4n than in 2n Arabidopsis; furthermore, the reduced silencing in 4n Arabidopsis correlated with reduced accumulation of silencing-inducer RNAs. Methylation analysis both of independent 2n and 4n transgenic lines and of 2n and 4n progeny derived from the same 3n transgenic parent, indicated that transgenes are more methylated in 4n than 2n Arabidopsis. These results suggest that transgenes are transcriptionally repressed in the 4n background, resulting in expression levels lower than in the 2n background. Transgenes designed to silence endogenous genes express lower concentrations of silencing-inducer RNAs in 4n Arabidopsis plants, resulting in less effective silencing of target genes than in 2n Arabidopsis plants.
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, ACT 2601, Australia.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Finn
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: Smolilo
authors.forename: Neil A
authors.initials: NA
authors.lastname: Smith
authors.forename: Rosemary
authors.initials: R
authors.lastname: White
authors.forename: Abed
authors.initials: A
authors.lastname: Chaudhury
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Dennis
authors.forename: Ming-Bo
authors.initials: MB
authors.lastname: Wang
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant; D023061:Gene Order; D020868:Gene Silencing / Q000187:drug effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D011003:Ploidies; D034622:RNA Interference / Q000187:drug effects; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D019076:Transgenes
chemical_list: D016372:RNA, Antisense; D034741:RNA, Small Interfering; D005966:Glucuronidase