RESUMEN
The complete genome sequence of a cucurbit-infecting fabavirus was determined. Sequence analysis revealed that it had a genomic organization typical of fabaviruses, with genome segment sizes of 5870 nt (RNA-1) and 3294 nt (RNA-2). It shared CP and Pro-Pol amino acid sequence identities of 52.0-58.9% with those of reported fabaviruses. ELISA and western blots gave no cross-reactions between this cucurbit virus and broad bean wilt viruses 1 and 2. Based on molecular and serological criteria for species demarcation in the genus Fabavirus, the virus represents a distinct species, for which the species name Cucurbit mild mosaic virus (CuMMV) is proposed.
Asunto(s)
Cucurbita/virología , Fabavirus/genética , Fabavirus/aislamiento & purificación , Genoma Viral , ARN Viral/genética , Análisis de Secuencia de ADN , Anticuerpos Antivirales/inmunología , Western Blotting , China , Análisis por Conglomerados , Reacciones Cruzadas , Ensayo de Inmunoadsorción Enzimática , Fabavirus/clasificación , Fabavirus/inmunología , Datos de Secuencia Molecular , Filogenia , Homología de Secuencia de AminoácidoRESUMEN
The genomic RNA sequences of two genotypes of a brassica-infecting polerovirus from China were determined. Sequence analysis revealed that the virus was closely related to but significantly different from turnip yellows virus (TuYV). This virus and other poleroviruses, including TuYV, had less than 90% amino acid sequence identity in all gene products except the coat protein. Based on the molecular criterion (>10% amino acid sequence difference) for species demarcation in the genus Polerovirus, the virus represents a distinct species for which the name Brassica yellows virus (BrYV) is proposed. Interestingly, there were two genotypes of BrYV, which mainly differed in the 5'-terminal half of the genome.
Asunto(s)
Brassica/virología , Luteoviridae/genética , Luteoviridae/patogenicidad , Enfermedades de las Plantas/virología , Secuencia de Bases , China , Cartilla de ADN/genética , Genoma Viral , Genotipo , Luteoviridae/clasificación , Filogenia , ARN Viral/genéticaRESUMEN
Cucurbit aphid-borne yellows virus (CABYV) and Melon aphid-borne yellows virus (MABYV) have been found to be associated with cucurbit yellowing disease in China. Our report identifies for the first time a third distinct polerovirus, tentatively named Suakwa aphid-borne yellows virus (SABYV), infecting Suakwa vegetable sponge. To better understand the distribution and molecular diversity of these three poleroviruses infecting cucurbits, a total of 214 cucurbitaceous crop samples were collected from 25 provinces in China, and were investigated by RT-PCR and sequencing. Of these, 108 samples tested positive for CABYV, while 40 samples from five provinces were positive for MABYV, and SABYV was detected in only 4 samples which were collected in the southern part of China. Forty-one PCR-amplified fragments containing a portion of the RdRp gene, intergenic NCR and CP gene were cloned and sequenced. Sequence comparisons showed that CABYV isolates shared 78.0-79.2% nucleotide sequence identity with MABYV isolates, and 69.7-70.8% with SABYV. Sequence identity between MABYV and SABYV was 73.3-76.5%. In contrast, the nucleotide identities within each species were 93.2-98.7% (CABYV), 98.1-99.9% (MABYV), and 96.1-98.6% (SABYV). Phylogenetic analyses revealed that the polerovirus isolates fit into three distinct groups, corresponding to the three species. The CABYV group could be further divided into two subgroups: the Asia subgroup and the Mediterranean subgroup, based on CP gene and partial RdRp gene sequences. Recombination analysis suggested that MABYV may be a recombinant virus.
Asunto(s)
Luffa/virología , Luteoviridae/genética , Luteoviridae/aislamiento & purificación , Polimorfismo Genético , China , Clonación Molecular , Análisis por Conglomerados , Luteoviridae/clasificación , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN , Homología de Secuencia , Proteínas Virales/genéticaRESUMEN
The complete RNA genomes of a Chinese isolate of cucurbit aphid-borne yellows virus (CABYV-CHN) and a new polerovirus tentatively referred to as melon aphid-borne yellows virus (MABYV) were determined. The entire genome of CABYV-CHN shared 89.0% nucleotide sequence identity with the French CABYV isolate. In contrast, nucleotide sequence identities between MABYV and CABYV and other poleroviruses were in the range of 50.7-74.2%, with amino acid sequence identities ranging from 24.8 to 82.9% for individual gene products. We propose that CABYV-CHN is a strain of CABYV and that MABYV is a member of a tentative distinct species within the genus Polerovirus.