RNAi-derived field resistance to Cassava brown streak disease persists across the vegetative cropping cycle
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Date
2014
Journal Title
Journal ISSN
Volume Title
Publisher
GM Crops & Food
Abstract
A confined field trial was established to determine durability of RNAi-mediated resistance to Cassava brown streak
disease (CBSD). Stem cuttings were obtained from field-grown cassava plants of cv 60444 transgenic for construct p718,
consisting of an 894 bp inverted repeat sequence from the Ugandan Cassava brown streak virus (UCBSV) coat protein.
Plants were established from three transgenic lines previously shown to provide complete resistance to UCBSV and
differing levels of protection to the non-homologous virus species Cassava brown streak virus (CBSV), and grown for 11
months. CBSD symptoms were observed on shoots and storage roots of all non-transgenic cv 60444 control plants and
transgenic lines p718–002 and p718–005, but not on p718–001. RT-PCR diagnostic showed tissues of plant lines p718–002
and p718–005 to be infected with CBSV, but free of UCBSV. All leaves and roots of p718–001 plants were confirmed to
carry no detectable levels of either pathogen. Plants of cv 60444 in this field trial showed severe cassava mosaic disease
symptoms, indicating that presence of replicating geminiviruses did not cause significant suppression of RNAi-mediated
resistance to CBSD. Resistance to CBSD across a vegetative cropping cycle confirms earlier field data, and provides an
important step in proof of concept for application of RNAi technology to control of CBSD under conditions encountered
in farmers’ fields.
Description
Keywords
Cassava brown streak disease, RNAi-mediated resistance, Cassava, Transgenic, Confined field trial, Uganda
Citation
John Odipio, Emmanuel Ogwok, Nigel J Taylor, Mark Halsey, Anton Bua, Claude M Fauquet & Titus Alicai (2014) RNAi-derived field resistance to Cassava brown streak disease persists across the vegetative cropping cycle, GM Crops & Food, 5:1, 16-19, DOI: 10.4161/ gmcr.26408