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The Genetic Basis of High Resistance to Rice Yellow Mottle Virus (RYMV) in Cultivars of Two Cultivated Rice Species

October 1999 , Volume 83 , Number  10
Pages  931 - 935

M. N. Ndjiondjop and L. Albar , IRD-GeneTrop, BP 5045, 34032 Montpellier Cedex 1, France ; D. Fargette , CIRAD/IRD-LPRC, BP 5035, 34032 Montpellier Cedex 1, France ; C. Fauquet , ILTAB/IRD-TSRI, BCC 206, 10550 North Torrey Pines Road, La Jolla, CA 92037 ; and A. Ghesquière , IRD-GeneTrop, BP 5045, 34032 Montpellier Cedex 1, France

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Accepted for publication 16 June 1999.

Three cultivars of Oryza sativa (IR64, Azucena, and Gigante) and four cultivars of O. glaberrima (Tog5681, Tog5673, CG14, and SG329) were evaluated for their resistance to two isolates of rice yellow mottle virus (RYMV) by enzyme-linked immunosorbent assay (ELISA) and symptomatology. Cultivars Tog5681 and Gigante were highly resistant, and no symptoms were observed when either virus isolate was inoculated at 10 or 20 days postgermination and assayed by ELISA at 7, 14, 22, 35, 50, or 64 days postinoculation. Azucena showed a partial resistance, whereas the other cultivars were susceptible. Symptom appearance was associated with increase in ELISA absorbance in the systemically infected leaves. The best discrimination among the cultivars occurred when the plants were inoculated at 10 days postgermination. Crosses were made between the highly resistant (Gigante and Tog5681) and the susceptible (IR64) cultivars to determine the genetic basis of resistance to RYMV. Evaluation of F1 hybrids and interspecific progenies, as well as the segregation of resistance in F2 and F3 lines of the IR64 × Gigante cross, provided results consistent with the presence of a single recessive resistance gene common to Tog5681 and Gigante.

Additional keywords: Africa, monogenic resistance, sobemovirus

© 1999 The American Phytopathological Society