Transgenic RNA interference (RNAi)-derived field resistance to cassava brown streak disease
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
Molecular plant pathology
Abstract
Cassava brown streak disease (CBSD), caused by the Ipomoviruses
Cassava brown streak virus (CBSV) and Ugandan Cassava brown
streak virus (UCBSV), is considered to be an imminent threat to
food security in tropical Africa. Cassava plants were transgenically
modified to generate small interfering RNAs (siRNAs) from truncated
full-length (894-bp) and N-terminal (402-bp) portions of the
UCBSV coat protein (DCP) sequence. Seven siRNA-producing lines
from each gene construct were tested under confined field trials at
Namulonge, Uganda. All nontransgenic control plants (n = 60)
developed CBSD symptoms on aerial tissues by 6 months after
planting, whereas plants transgenic for the full-length DCP
sequence showed a 3-month delay in disease development, with
98% of clonal replicates within line 718-001 remaining symptom
free over the 11-month trial. Reverse transcriptase-polymerase
chain reaction (RT-PCR) diagnostics indicated the presence of
UCBSV within the leaves of 57% of the nontransgenic controls,
but in only two of 413 plants tested (0.5%) across the 14 transgenic
lines. All transgenic plants showing CBSD were PCR positive
for the presence of CBSV, except for line 781-001, in which 93% of
plants were confirmed to be free of both pathogens. At harvest,
90% of storage roots from nontransgenic plants were severely
affected by CBSD-induced necrosis. However, transgenic lines 718-
005 and 718-001 showed significant suppression of disease, with
95% of roots from the latter line remaining free from necrosis and
RT-PCR negative for the presence of both viral pathogens. Crossprotection
against CBSV by siRNAs generated from the full-length
UCBSV DCP confirms a previous report in tobacco.The information
presented provides proof of principle for the control of CBSD by
RNA interference-mediated technology, and progress towards the
potential control of this damaging disease.
Description
Keywords
Transgenic RNA interference (RNAi), Field resistance, Cassava brown streak disease
Citation
Ogwok, E., Odipio, J., Halsey, M., Gaitán‐Solís, E., Bua, A., Taylor, N. J., ... & Alicai, T. (2012). Transgenic RNA interference (RNA i)‐derived field resistance to cassava brown streak disease. Molecular plant pathology, 13(9), 1019-1031. DOI: 10.1111/J.1364-3703.2012.00812.X