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A repetitive DNA fragment carrying a hot spot for de novo DNA methylation enhances expression variegation in tobacco and petunia
Author(s) -
Lohuis Michael ten,
Müller Andreas,
Heidmann Iris,
Niedenhof Ingrid,
Meyer Peter
Publication year - 1995
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1995.8060919.x
Subject(s) - petunia , biology , dna methylation , genetics , dna , methylation , microbiology and biotechnology , variegation (histology) , gene , gene expression
Summary A 1.6 kb r e p etitive DNA s equence (RPS) from Petunia hybrida was identified that destabilizes expression of a GUS marker transgene. Following polyethylene glycol (PEG)‐mediated tobacco and petunia protoplast transformations, GUS expression patterns analysed on callus and plant levels were clearly more variable when constructs contained the RPS sequence. The effect on transgens expression required chromosomal integration since the two different RPS constructs employed did not exhibit reduced levels of GUS activities in transient assays. DNA methylation analysis implies a hypermethylated default state of endogenous RPS copies present in the petunia genome. Analysis of the transgens DNA in different transgenic tobacco plants showed almost complete hypermethylation of a particular Hha l site of the RPS sequence. It is proposed that, due to the presence of specific signals within the RPS region or based on interaction of RPS with other endogenous homologous sequences, RPS functions as an initiation region for de novo methylation and induces expression variegation in adjacent sequences.