GENETIC DIVERSITY IN GEMINIVIRUSES CAUSING BEAN GOLDEN MOSAIC DISEASE - THE NUCLEOTIDE-SEQUENCE OF THE INFECTIOUS CLONED DNA COMPONENTS OF A BRAZILIAN ISOLATE OF BEAN GOLDEN MOSAIC GEMINIVIRUS

The complete nucleotide (nt) sequence of a Brazilian isolate of bean golden mosaic geminivirus (BGMV-BZ) was determined from the infectious cloned DNA components. The genome of BGMV-BZ was divided between two DNA components, DNA-A (2,617 nt) and DNA-B (2,580 nt), which had little sequence identity except for a 181-nt common region present in both molecules. The genomic organization of BGMV-BZ was similar to that of other bipartite whitefly-transmitted geminiviruses, with six open reading frames (ORFs) encoding putative proteins >10 kDa, four on DNA-A (one in the viral [+] and three in the viral complementary sense [-]) and two on DNA-B (one in the viral and one in the viral complementary sense). All six BGMV-BZ ORFs were analogous to corresponding ORFs in other whitefly-transmitted geminiviruses. The homology between BGMV-BZ sequences and those of a BGMV isolate from Puerto Rico (PR) were relatively low. BGMV-BZ sequences were no more closely related to BGMV-PR than to other distinct geminiviruses from South America, such as tomato golden mosaic geminivirus. Pseudo-recombinants made by mixing the infectious cloned DNAs of BGMV-BZ and a BGMV isolate from Guatemala (GA), which was very similar to BGMV-PR, were not infectious. These results support previous observations of differences in sap-transmissibility and bean genotype reactions between BGMV isolates and indicate that at least two distinct types of BGMV exist, designated type I and II.