2017 ASHS Annual Conference

Hawaii’s banana industry has experienced losses due to banana bunchy top virus (BBTV) for three decades. ‘Williams’ (Cavendish AAA) and ‘Santa Catarina Prata’ (Pome AAB) are important commercial clones in Hawaii that are susceptible. Our objective was to screen banana germplasm to identify naturally occurring resistance to BBTV. A collection of 46 genotypes in 6 replicates was assembled at Waimanalo Experiment Station in 2012, including clones that are representative of the major genomic groups (AA, AAA, AAAB, AAB, AB, ABB, and BB) and related wild species. The aphid vector Pentalonia nigronervosa (Coquerel) was manually transported from a BBTV-infected field to the collection site, and virus disease development was monitored for 31 months. Thirty clones developed disease symptoms in half or more of the reps within this time period. Among the best performers in terms of BBTV resistance, productivity, and fruit quality were two Gros Michel variants (‘Cocos’ and ‘Highgate’) and two Pisang Awak clones (‘Kayinja’ and ITC0459). All reps of ‘Highgate’ and a seedy wild Musa acuminata ssp. malaccensis (Simmonds) remained symptomless and PCR-negative for BBTV for the duration of the field trial. More stringent aphid inoculations of 3 to 6 reps of the best clones in greenhouse cages revealed their superiority to susceptible check ‘Dwarf Cavendish’, which became infected within the first month. All reps of ‘Highgate’ tested BBTV-positive by PCR, but only one plant showed obvious symptoms at the end of the 3-month trial. ‘Cocos’ showed more typical symptoms in two reps, and the Pisang Awak clones and Musa acuminata ssp. malaccensis remained mostly symptomless. The BBTV-resistant banana selections are not intended to replace standard commercial varieties, but to provide small growers, who might typically sell their fruit at local farmers’ markets, with clones that have a longer BBTV-free production window and a greater economic return before virus infection necessitates replanting from clean stock. A grant-funded program to propagate and distribute clean tissue-cultured plants of the BBTV-resistant clones to Hawaii growers is recently under way.