VIEW ARTICLE

Genetics

Molecular Mapping of Resistance to Rice Tungro Spherical Virus and Green Leafhopper. L. S. Sebastian, Plant Breeding, Genetics and Biochemistry Division, International Rice Research Institute (IRRI), P.O. Box 933, Manila 1099, The Philippines, and Philippine Rice Research Institute, Maligaya, Muņoz, Nueva Ecija, The Philippines; R. Ikeda(2), N. Huang(3), T. Imbe(4), W. R. Coffman(5), and S. R. McCouch(6). (2)Plant Breeding, Genetics and Biochemistry Division, International Rice Research Institute (IRRI), P.O. Box 933, Manila 1099, The Philippines, and Rice Breeding Technology Laboratory, NARC, 3-1-1, Kannondai, Tsukuba, Ibaraki 305, Japan; (3)(4)Plant Breeding, Genetics and Biochemistry Division, International Rice Research Institute (IRRI), P.O. Box 933, Manila 1099, The Philippines; (5)Department of Plant Breeding and Biometry, Ithaca, NY 14853-1091; (6)Plant Breeding, Genetics and Biochemistry Division, International Rice Research Institute (IRRI), P.O. Box 933, Manila 1099, The Philippines, and Department of Plant Breeding and Biometry, Ithaca, NY 14853-1091. Phytopathology 86:25-30. Accepted for publication 2 October 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/Phyto-86-25.

The green leafhopper (GLH), Nephotettix virescens (Distant), vectors rice tungro spherical virus (RTSV) and rice tungro bacilliform virus (RTBV) to cause tungro disease in rice (Oryza sativa L.). Results of this study demonstrate that a dominant gene(s) conferring resistance to GLH and RTSV is located within 5.5 cM of restriction fragment length polymorphism (RFLP) marker RZ 262 on rice chromosome 4. Segregation analysis was based on a cross between rice cultivars ARC11554 (resistant to both GLH and RTSV) and TN1 (susceptible to GLH, RTSV, and RTBV). Two hundred forty F₂ plants were evaluated for GLH resistance in antibiosis experiments, and 111 additional F₂ plants from the same cross were evaluated for virus resistance by enzyme-linked immunosorbent assay (ELISA). Forced feeding by viruliferous GLH was used to inoculate plants with both RTSV and RTBV. RTSV resistance cosegregated with GLH resistance, and high levels of RTBV in plants resistant to both GLH and RTSV indicated that inoculation was effective. Future studies will clarify whether resistance to GLH and RTSV in ARC11554 is governed by two linked genes or is the result of pleiotropy at a single locus. This is the first report of the map location of an RTSV resistance gene in rice and the first time a GLH resistance gene has been reported on chromosome 4.