CBN-V Video Archives - S8-14
The Use of Bud Grafting to Evaluate Cassava for Resistance to African Cassava Mosaic Virus

Ogbe F.O.^{1, 2}, A.G.O. Dixon¹ and G.I. Atiri³ and G. Thottappilly¹

1. International Institute of Tropical Agriculture, Ibadan, Nigeria
f.ogbe@cgiar.org
2. National Root Crops Research Institute, Umudike, Umuahia, Nigeria
3. Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria

        A non-conventional bud graft-inoculation in which a virus-free cassava bud (scion) was grafted unto virus-infected rootstock instead of grafting an infected bud unto virus-free rootstock was effective in the assessment of resistance in cassava to African cassava mosaic virus. Successful graft union requires the use of young plants of about 6 weeks old and careful handling of the bud (scion) and the rootstock to avoid extensive bruises. Very critical to graft union is the removal of buds on the planted stem cutting and the lateral and apical buds of the rootstock but allowing the leaves to stay for 4–5 days. Thereafter, the rootstock could be topped, 4–5 cm above the grafted bud, to remove all leaves. Topping rootstock to remove most leaves just after grafting decreased graft union by between 10% (TMS M94/0583) and 90% (TMS 91/02327). Differences in the strength of symptoms produced by the nine genotypes tested indicated differences in their resistance to the virus, which could not be assessed under field condition due to either lack of symptoms or inconspicuous symptoms on them. The grafting method is useful to differentiate between field resistance response and immunity to infection.

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