Molecular Mapping of Resistance to Rice Tungro Spherical Virus and Green Leafhopper

Abstract

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 saliva 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 TNI (susceptible to GLH, RTSV, and RTBV). Two hundred forty F 2 plants were evaluated for GLH resistance in antibiosis experiments, and 111 additional F 2 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.