Incidência e caracterização molecular de badnavirus em bancos de germoplasma de inhame (Dioscorea spp.) no Brasil

Abstract

The culture of yam plays great importance in power in regions of Africa where high production rates are observed. In Brazil, the Northeast stands out as the main producer, which serves as a food source and helps in generating employment and income for many families. Several disease problems, affect the culture of yam, among which we can highlight the viruses. Badnavirus cause diseases in crops of economic importance, such as observed in banana and sugarcane, and infections with these viruses have been observed in yam production in various regions. Worldwide are reported by ICTV two species badnavirus causing infections in yams, Dioscorea alata bacilliform virus (DBALV) and Dioscorea bacilliform virus sansibarensis (DBSNV). The Badnavirus genus (family Caulimoviridae) comprises plant genome to double-stranded circular DNA (dsDNA), replicate through an RNA intermediate, and have the capacity to integrate their DNA into the host genome virus. This fact is important since the discovery of viral sequences present in the genome taro alert to the utmost caution as regards the exchange of germplasm, thus preventing viral spread. The information about badnavirus in yam in Brazil are still scarce, so are extremely important studies that may contribute to a better understanding of the occurrence and distribution of these viruses in the country. Thus, the objective of this study was to determine the incidence and molecularly characterize badnavirus in yam germplasm banks in Brazil. The yam samples were obtained from the germplasm collections of the Escola de Agriculture Luiz (ESALQ/USP), Universidade Federal de Viçosa (UFV) and Universidade Federal do Reconcavo Baiano (UFRB). The average incidence of Badnavirus in samples of yam germplasm banks evaluated was 75.3 %. Analyses of paired comparisons and phylogenetic sequences of 42 nucleotides of the RT/RNase/H region revealed that the two species currently accepted by ICTV Badnavirus were detected in the evaluated accessions. Beyond espissomais species were also found endogenous sequences that showed the percentage of nucleotide identity ranging from 89% to 100% with endogenous Dioscorea bacilliform virus (eDBV) groups 9 and 12. The findings agree with the hypothesis of widespread dissemination of DBALV yam -producing areas and records the first report of DBSNV infecting yam in Brazil.