resistance in Cassava - ETH - North-South Centre North-South Centre
resistance in Cassava - ETH - North-South Centre North-South Centre
resistance in Cassava - ETH - North-South Centre North-South Centre
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Evaluation of different strategies to<br />
eng<strong>in</strong>eer <strong>Cassava</strong> Brown Streak<br />
Virus (CBSV) <strong>resistance</strong> <strong>in</strong> <strong>Cassava</strong><br />
(Manihot esculenta)<br />
Isabel Moreno<br />
<strong>North</strong>-<strong>South</strong> <strong>Centre</strong> Colloquium<br />
“Selected aspects of susta<strong>in</strong>able development”<br />
21.05.10
Importance<br />
Fifth staple after rice, wheat, maize, and potato<br />
Source of E for more than 800 million people<br />
In Sub-Saharan African regions, up to 60% of the<br />
daily calories <strong>in</strong>take<br />
Animal Feed<br />
Raw material starch <strong>in</strong>dustry<br />
•Tolerant to poor soils<br />
•Drought tolerance<br />
•Easily propagated by stem cutt<strong>in</strong>gs<br />
•Susceptible to virus diseases<br />
• Low nutritional value<br />
• Rapid deterioration<br />
•Relatively <strong>in</strong>expensive to produce<br />
( FAO, 2008)
Constra<strong>in</strong>ts: Pests and Diseases<br />
<strong>Cassava</strong> Mosaic<br />
Disease<br />
40-100%<br />
<strong>Cassava</strong> Brown<br />
Streak Disease<br />
30-100%<br />
Whiteflies<br />
<strong>Cassava</strong><br />
mealybug<br />
<strong>Cassava</strong><br />
bacterial<br />
blight<br />
Green spider<br />
mite
The <strong>Cassava</strong><br />
Mosaic Disease<br />
(CMD)<br />
A viral disease endemic <strong>in</strong><br />
SS-Africa.<br />
India and Sri lanka<br />
Not recorded <strong>in</strong> the Americas<br />
Vectored by the white fly<br />
(Bemisia tabaci)
Integrated control strategy<br />
<br />
Virus free plant<strong>in</strong>g material<br />
<br />
Field sanitation<br />
<br />
Cultural practice<br />
The most efficient form of control is resistant<br />
varieties which take 6-10 years to develop
IITA (1930)<br />
Sources of <strong>resistance</strong><br />
I. 3rd Backcross<strong>in</strong>g : <strong>Cassava</strong> X Manihot glaziovii<br />
(1947)<br />
II. Local Nigerian varieties (1990)<br />
CIAT (1997)<br />
• Fregene 2000 (CMD1 gene)Recessive gene<br />
• Akano et al 2002 (CMD2 gene) Dom<strong>in</strong>ant gene<br />
• L<strong>in</strong>kage SSRY28 y NS158 (Akano 2002; Zárate 2002)<br />
• Positional clon<strong>in</strong>g of CMD2 gene (Moreno 2002-2007)
Potyviridae<br />
•Encapsidatedfilamentous<br />
particles<br />
•ssRNA+ genome<br />
CBSV<br />
Uganda<br />
Kenya<br />
Tanzania<br />
Mozambique<br />
(Hillocks & Jenn<strong>in</strong>gs 2003)
Lake Victoria bas<strong>in</strong> isolates<br />
and coastal lowland isolates<br />
are separated populations.<br />
(Mbanzibwa et al 2009)<br />
Clade 1=Kenia, Uganda,<br />
Malawi- CBSV and Clade 2=<br />
Mozambique- CBSMV.<br />
(W<strong>in</strong>ter et al 2010)
Prote<strong>in</strong> & RNAmediated<br />
<strong>resistance</strong><br />
Virus detection<br />
and<br />
<strong>in</strong>fection<br />
Evaluation of different<br />
strategies to eng<strong>in</strong>eer<br />
CBSV <strong>resistance</strong> <strong>in</strong><br />
<strong>Cassava</strong>
Prote<strong>in</strong> -<br />
mediated<br />
<strong>resistance</strong>
1.1 CBSV-Coat Prote<strong>in</strong> construct<br />
Prote<strong>in</strong> -<br />
mediated<br />
<strong>resistance</strong>
RNA -<br />
mediated<br />
<strong>resistance</strong><br />
PTGS<br />
(Waterhouse & Fusaro 2006)
1.2 Sense and antisense CBSV<br />
constructs<br />
RNA -<br />
mediated<br />
<strong>resistance</strong>
1.3 Hairp<strong>in</strong> CBSD constructs
Virus detection<br />
and<br />
<strong>in</strong>fection
2. Resistance evaluations<br />
Infection= Rootstock:CBSV <strong>in</strong>fected, Graft: <strong>Cassava</strong><br />
transgenic l<strong>in</strong>es.<br />
Scion<br />
Rootstock<br />
Viral and transcript level quantification
Success story <strong>in</strong> Potyvirus <strong>resistance</strong><br />
Papaya R<strong>in</strong>gspot Virus <strong>in</strong> Hawaii<br />
Papaya severely<br />
<strong>in</strong>fected by PRSV.<br />
CP Transgenic papaya <strong>in</strong>oculated with<br />
PRSV (left).<br />
Commercialization of transgenic papaya<br />
l<strong>in</strong>e 55-1 s<strong>in</strong>ce 1995 (Gonsalves, D. 1998)
Prof Wilhelm Gruissem<br />
Dr. Hervé Vanderschuren<br />
CASSAVA GROUP<br />
Dr. M.N. Maruthi (NRI, UK)<br />
Dr. Oluwole Ariyo (Columbus<br />
University, USA)<br />
THANK YOU
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