Diagnose e caracterização molecular de espécies de Badnavirus que causam a estria da bananeira no Brasil

Abstract

The virus disease known as banana streak, caused by species of Badnavirus genus, was originally associated with the virus species called Banana streak virus (BSV). However, to date, other 9 species of the same genus that are also capable of inducing the same symptoms have been proposed, in different places in the world where this plant is grown. As in Brazil Badnavirus species associated with banana streak are not well known, the aim of this study was to collect and characterize viral isolates in banana crops located in different Brazilian regions. Samples were collected in six Brazilian states, and were initially tested by PCR using degenerate primers. The PCR positive samples were subjected to rolling circle amplification method (RCA) to confirm the presence of episomal viruses, and then nine isolates that were RCA positive were again subjected to amplification of genomic 540 bp fragments, located in the gene RT/RNase H for sequencing and analysis, aiming the identification of species. Following the criteria of Badnaviruses classification, the isolates named MGMYSR and CEPRCA were classified as Banana streak MY virus (BSMYV), with nucleotides identity between 94 and 97%, the RJMACA and RJTQUI isolates were classified as Banana streak UC virus (BSUCV), with identities between 93 and 94%, the ESTERRA 1, MGJAPI and PRCAT2 isolates as Banana streak GF virus (BSGFV), with identities between 87 and 98%, and the SPTAM isolate as Banana streak UG virus (BSUGV). The isolate ESTERRA 2 presented identities below 80% with the species of Badnavirus available in GenBank, however, showed 95% identity with the species found recently in Brazil and named Banana streak Brazilian A virus (BSBAV) whose reference in GenBank is KJ201876, confirming the presence of a new species of Badnavirus in this country. The RCA technique allowed the diagnosis of episomal sequences in 31 samples from seven Brazilian states. Besides highlighting the great variability of this virus, this study shows the presence of species that has not been reported previously, indicating the need to further explore those important Badnaviruses in Brazil.