Survey and molecular characterization of the Banana bunchy top virus (BBTV) in the southern region of Mozambique - Chókwè District

Abstract

Banana bunchy top disease is the most devastating viral disease of banana trees worldwide and is caused by the Banana bunchy top virus (BBTV). This virus has already been found in 36 countries worldwide and is currently absent in Central and South America. Based on the R-DNA sequence, the BBTV isolates around the world were classified into the Pacific Indian Ocean (PIO) group and the Southwest Asian (SEA) group. These data help to understand the geographic origin of the isolates, guiding preventive control measures. In 2016, the virus was detected for the first time in the irrigated perimeter of the Chókwè district, located in the first zone in the southern region of Mozambique. However, there is no study to determine its incidence and genetic characteristics. This study initially aimed to survey the incidence and distribution of isolates and their genomic features. Sampling was made in this area, collecting 175 samples of plants with suspected infection in 23 fields of 3 commercial farms and 8 farms from familiar growers in the four administrative posts of the district. The survey results indicated that the virus was present in 19 of the 23 sampled fields. The average percentage of incidence was 54.3%, with a minimum rate of 20% in farm 9 and a maximum of 100% in farm 2. No infected samples were found on the commercial farm 6. The nucleotide sequences of the S-DNA of the isolates analyzed were quite conserved, ranging from 97% to 100%. The same was observed for the R-DNA sequences, which presented the vast majority of identities ranging between 98% and 100% among Chókwè isolates and above 90% compared with GenBank isolates. Phylogenetic analysis showed that these isolates behaved as PIO isolates, showing greater proximity to the Malawi JQ820453 isolates, suggesting that they may have originated in this country. This is the first report of studies conducted on the incidence and molecular characteristics of isolates of the Banana bunchy top virus in Mozambique, warning to the need to take urgent measures to control BBTV in this country.