Transgenic cassava resistance to African cassava mosaic virus is enhanced by viral DNA-A bidirectional promoter-derived siRNAs.
Expression of double-stranded RNA (dsRNA) homologous to virus sequences can effectively interfere with RNA virus infection in plant cells by triggering RNA silencing. Here we applied this approach against a DNA virus, African cassava mosaic virus (ACMV), in its natural host cassava. Transgenic cassava plants were developed to express small interfering RNAs (siRNA) from a CaMV 35S promoter-controlled, intron-containing dsRNA cognate to the common region-containing bidirectional promoter of ACMV DNA-A. In two of three independent transgenic lines, accelerated plant recovery from ACMV-NOg infection was observed, which correlates with the presence of transgene-derived siRNAs 21-24 nt in length. Overall, cassava mosaic disease symptoms were dramatically attenuated in these two lines and less viral DNA accumulation was detected in their leaves than in those of wild-type plants. In a transient replication assay using leaf disks from the two transgenic lines, strongly reduced accumulation of viral single-stranded DNA was observed. Our study suggests that a natural RNA silencing mechanism targeting DNA viruses through production of virus-derived siRNAs is turned on earlier and more efficiently in transgenic plants expressing dsRNA cognate to the viral promoter and common region.
Vanderschuren
Hervé
H
Institute of Plant Sciences, ETH Zurich, Universitätstrasse 2, Zürich, 8092, Switzerland.
Akbergenov
Rashid
R
Pooggin
Mikhail M
MM
Hohn
Thomas
T
Gruissem
Wilhelm
W
Zhang
Peng
P
D001483:Base Sequence; D017931:DNA Primers; D004279:DNA, Viral / Q000235:genetics*; D002365:Manihot / Q000821:virology*; D008969:Molecular Sequence Data; D009029:Mosaic Viruses / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics / Q000821:virology; D030821:Plants, Genetically Modified / Q000821:virology*; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics
D017931:DNA Primers; D004279:DNA, Viral; D034741:RNA, Small Interfering; D012367:RNA, Viral