Comprehensive molecular profiling and indexing of endogenous banana streak virus (BSV) species in Musa spp. germplasm
Caldas, Camila Pestana | de Oliveira Amorim, Vanusia Batista | Chabannes, Matthieu | Iskra Caruana, Marie-Line | Galzi, Serge | Nogueira Pestana, Kátia | Fortes Ferreira, Claudia | Amorim, Edson Perito
Banana streak virus (BSV) species belong to the family Caulimoviridae, genus Badnavirus and may occur in two forms: endogenous (eBSV, integrated into the banana genome) and episomal. One of the greatest concerns of having complete eBSV sequences integrated into the Musa balbisiana 'B' genome is that they can 'awaken' under stressful conditions, leading to systemic infection of the plants. Brazil retains one of the largest banana germplasm collections in the world, harbouring accessions with Musa acuminata 'A' and M. balbisiana 'B' genomes and all combinations of ploidy levels (diploids, triploids and tetraploids). Three hundred accessions from the banana germplasm collection and 38 in vitro accessions were analysed with primers specific to banana streak GF virus (eBSGFV and BSGFV), banana streak IM virus (eBSIMV and BSIMV) and banana streak OL virus (eBSOLV and BSOLV). The 162 accessions without the B genome did not harbour any integrated BSV sequences, as expected. All eight accessions with diploid BB genome had the infective eBSOLV and eBSGFV alleles but were not infected by episomal BSV. Conversely, nearly 14% of interspecific hybrids were infected by BSV, with a higher prevalence of the BSOLV species (13 plants) compared to BSGFV (six plants). Interestingly, no plant was infected by BSIMV. Most bananas developed by the banana genetic breeding programme have B genome in their constitution, so a screening method to detect and predict the disease is of utmost necessity. This is the first report of molecular characterisation of BSV species in such a large number of samples in Brazil.
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