Transgene-induced gene silencing is not affected by a change in ploidy level.
BACKGROUND
Whole genome duplication, which results in polyploidy, is a common feature of plant populations and a recurring event in the evolution of flowering plants. Polyploidy can result in changes to gene expression and epigenetic instability. Several epigenetic phenomena, occurring at the transcriptional or post-transcriptional level, have been documented in allopolyploids (polyploids derived from species hybrids) of Arabidopsis thaliana, yet findings in autopolyploids (polyploids derived from the duplication of the genome of a single species) are limited. Here, we tested the hypothesis that an increase in ploidy enhances transgene-induced post-transcriptional gene silencing using autopolyploids of A. thaliana.


RESULTS
Diploid and tetraploid individuals of four independent homozygous transgenic lines of A. thaliana transformed with chalcone synthase (CHS) inverted repeat (hairpin) constructs were generated. For each line diploids and tetraploids were compared for efficiency in post-transcriptional silencing of the endogenous CHS gene. The four lines differed substantially in their silencing efficiency. Yet, diploid and tetraploid plants derived from these plants and containing therefore identical transgene insertions showed no difference in the efficiency silencing CHS as assayed by visual scoring, anthocyanin assays and quantification of CHS mRNA.


CONCLUSIONS
Our results in A. thaliana indicated that there is no effect of ploidy level on transgene-induced post-transcriptional gene silencing. Our findings that post-transcriptional mechanisms were equally effective in diploids and tetraploids supports the use of transgene-driven post-transcriptional gene silencing as a useful mechanism to modify gene expression in polyploid species.
Pignatta
Daniela
D
Department of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America.
Dilkes
Brian
B
Wroblewski
Tadeusz
T
Michelmore
Richard W
RW
Comai
Luca
L
D016960:Agrobacterium tumefaciens / Q000235:genetics; D000872:Anthocyanins / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics; D020440:Gene Duplication; D020868:Gene Silencing; D030821:Plants, Genetically Modified / Q000235:genetics / Q000382:microbiology; D011003:Ploidies; D016133:Polymerase Chain Reaction; D011123:Polyploidy; D018749:RNA, Plant / Q000235:genetics; D014158:Transcription, Genetic; D019076:Transgenes / Q000235:genetics*
D000872:Anthocyanins; D018749:RNA, Plant