|Authors: ||C. Niyongere, E. Ateka, T. Losenge, G. Blomme, P. Lepoint|
|Keywords: ||Banana bunchy top virus, disease incidence, latent infections, Pentalonia nigronervosa|
Banana bunchy top disease (BBTD), caused by the Banana bunchy top virus (BBTV), is reported as one of the most devastating diseases affecting banana and plantain cultivation worldwide.
In order to identify putative sources of resistance, a cultivar screening trial comprising 40 Musa genotypes was established in March 2007 at the ISABU Mparambo research station in northwestern Burundi (893 m a.s.l.). Dessert bananas (AAA group), East African highland bananas (AAA, EAHB), plantains (AAB), cooking bananas (ABB), a tetraploid hybrid and wild diploid bananas (Musa acuminate and Musa balbisiana) were assessed.
Ten plants per genotype were planted in a completely randomised design with border rows consisting of BBTV-infected ‘Yangambi Km 5’ (AAA) plants.
Colonies of Pentalonia nigronervosa collected in BBTV-infected fields were released in the plot to enhance disease spread.
Twenty-eight months after trial establishment, 32 genotypes have shown typical banana bunchy top symptoms.
The first symptoms appeared 80 days after trial establishment on ‘Yangambi Km 5’. Twenty-eight months after trial establishment, only eight genotypes [Musa balbisiana type Tani (BB), ‘Kayinja’ (ABB), ‘FHIA-03’ (AABB), ‘Prata’ (AAB), ‘Gisandugu’ (ABB), ‘Pisang Awak’ (ABB), ‘Saba’ (ABB) and ‘Highgate’ (AAA, Gros Michel subgroup)] have not manifested typical disease symptoms on any of the ten plants per genotype.
Plant samples taken from these visibly healthy cultivars and analysed at a molecular level [at the Faculté Universitaire des Sciences Agronomiques de Gembloux (FUSAGx) in Belgium] indicated the presence of the virus in ‘Pisang Awak’, ‘Saba’ and ‘Highgate’. These genotypes can be considered as BBTD tolerant.
They could potentially act as a reservoir for the virus.
Further diagnostic tests will be carried out on the five BBTV-free genotypes to confirm the extent of latent infections.
Preliminary results indicate that genotypes with one or two B genomes tend to be more tolerant to BBTD.
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