The genomic RNA-1 and RNA-2 of Rice hoja blanca virus (RHBV) were sequenced and analyzed. A clone obtained from RNA-1 is homologous to the 3' end of the Rice stripe virus (RSV) replicase gene, whereas two open reading frames were located in RNA-2 in an ambisense arrangement. The 94 kDa PC2, has features typical of viral membrane-glycoproteins found in Phleboviruses (Bunyaviridae), while the 23 kDa PV2 has two conserved domains also found in viral membrane-glycoproteins.;The genome of Echinochloa hoja blanca virus (EHBV), a tentative new tenuivirus species was partially sequenced. Sequence analyses showed that EHBV and RHBV RNAs-3 and -4 are 85--90% identical in the coding regions, but only 50% in their non-coding regions. EHBV RNA-5 is 1334 nucleotides long and contains a single open reading frame in the complementary sense RNA. It encodes a highly basic and hydrophilic 44 kDa protein (PC5). This data supports the notion that EHBV and RHBV are evolutionarily related, but may be regarded as separate species.;Costa Rican indica cultivar CR-1821 was transformed with genes derived from RHBV and the phosphinothricin-resistance gene (bar). The viral coat protein in sense, antisense and untranslatable forms were used for transformation under the control of the rice Actin 1 gene promoter. Fragments containing the 5' and 3' end of the coat protein gene and a clone with an internal deletion of the RNA-3 were also used. Transformed plants containing a single;copy of the coat protein gene showed high levels of tolerance to the herbicide BASTARTM (PPT). Progeny plants from several lines were evaluated for herbicide and virus resistance using viruliferous planthoppers (Tagosodes orizicolus). Most plants showed typical "hoja blanca" symptoms in the newly emerged leaves within four weeks after inoculation. Several plants did not develop any symptoms even after two or three rounds of virus inoculation. Coat protein could not be detected in T1-plants using specific polyclonal antibodies. Northern blot analysis did not revealed transcripts of the RHBV coat protein transgene in T1 plants.;TO plants were also recovered from transformation experiments using different fragments from the RHBV genome. The T1 progeny of herbicide resistant plants have not been tested.
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