title: A high level of transgenic viral small RNA is associated with broad potyvirus resistance in cucurbits.
abstract: Gene-silencing has been used to develop resistance against many plant viruses but little is known about the transgenic small-interfering RNA (t-siRNA) that confers this resistance. Transgenic cucumber and melon lines harboring a hairpin construct of the Zucchini yellow mosaic potyvirus (ZYMV) HC-Pro gene accumulated different levels of t-siRNA (6 to 44% of total siRNA) and exhibited resistance to systemic ZYMV infection. Resistance to Watermelon mosaic potyvirus and Papaya ring spot potyvirus-W was also observed in a cucumber line that accumulated high levels of t-siRNA (44% of total siRNA) and displayed significantly increased levels of RNA-dependent RNA (RDR)1 and Argonaute 1, as compared with the other transgenic and nontransformed plants. The majority of the t-siRNA sequences were 21 to 22 nucleotides in length and sense strand biased. The t-siRNA were not uniformly distributed throughout the transgene but concentrated in "hot spots" in a pattern resembling that of the viral siRNA peaks observed in ZYMV-infected cucumber and melon. Mutations in ZYMV at the loci associated with the siRNA peaks did not break this resistance, indicating that hot spot t-siRNA may not be essential for resistance. This study shows that resistance based on gene-silencing can be effective against related viruses and is probably correlated with t-siRNA accumulation and increased expression of RDR1.
authors: Department of Plant Pathology and Weed Sciences, ARO The Volcani Center, Bet Dagan 50250, Israel.
authors: Diana
authors: D
authors: Leibman
authors: Dalia
authors: D
authors: Wolf
authors: Vinod
authors: V
authors: Saharan
authors: Aaron
authors: A
authors: Zelcer
authors: Tzahi
authors: T
authors: Arazi
authors: Shiboleth
authors: S
authors: Yoel
authors: Victor
authors: V
authors: Gaba
authors: Amit
authors: A
authors: Gal-On
mesh_terms: D001483:Base Sequence; D028464:Cucurbita / Q000235:genetics* / Q000821:virology*; D015870:Gene Expression; D020868:Gene Silencing; D017343:Genes, Plant; D005814:Genes, Viral; D054884:Host-Pathogen Interactions / Q000235:genetics; D055029:Inverted Repeat Sequences; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000235:genetics / Q000517:prevention & control / Q000821:virology; D030821:Plants, Genetically Modified; D017800:Potyvirus / Q000235:genetics* / Q000472:pathogenicity*; D034741:RNA, Small Interfering / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
chemical_list: D034741:RNA, Small Interfering; D012367:RNA, Viral