Characterization of novel microsatellite markers in Musa acuminata subsp. burmannicoides, var. Calcutta 4.
BACKGROUND
Banana is a nutritionally important crop across tropical and sub-tropical countries in sub-Saharan Africa, Central and South America and Asia. Although cultivars have evolved from diploid, triploid and tetraploid wild Asian species of Musa acuminata (A genome) and Musa balbisiana (B genome), many of today's commercial cultivars are sterile triploids or diploids, with fruit developing via parthenocarpy. As a result of restricted genetic variation, improvement has been limited, resulting in a crop frequently lacking resistance to pests and disease. Considering the importance of molecular tools to facilitate development of disease resistant genotypes, the objectives of this study were to develop polymorphic microsatellite markers from BAC clone sequences for M. acuminata subsp. burmannicoides, var. Calcutta 4. This wild diploid species is used as a donor cultivar in breeding programs as a source of resistance to diverse biotic stresses.


RESULTS
Microsatellite sequences were identified from five Calcutta 4 BAC consensi datasets. Specific primers were designed for 41 loci. Isolated di-nucleotide repeat motifs were the most abundant, followed by tri-nucleotides. From 33 tested loci, 20 displayed polymorphism when screened across 21 diploid M. acuminata accessions, contrasting in resistance to Sigatoka diseases. The number of alleles per SSR locus ranged from two to four, with a total of 56. Six repeat classes were identified, with di-nucleotides the most abundant. Expected heterozygosity values for polymorphic markers ranged from 0.31 to 0.75.


CONCLUSIONS
This is the first report identifying polymorphic microsatellite markers from M. acuminata subsp. burmannicoides, var. Calcutta 4 across accessions contrasting in resistance to Sigatoka diseases. These BAC-derived polymorphic microsatellite markers are a useful resource for banana, applicable for genetic map development, germplasm characterization, evolutionary studies and marker assisted selection for traits.
Miller
Robert Ng
RN
Universidade de Brasília, Campus Universitário Darcy Ribeiro, Instituto de Ciências Biológicas, Departamento de Biologia Celular, Asa Norte, Brasília, Brazil. robertmiller@unb.br.
Passos
Marco An
MA
Menezes
Natalia Np
NN
Souza
Manoel T
MT
do Carmo Costa
Marcos M
MM
Rennó Azevedo
Vânia C
VC
Amorim
Edson P
EP
Pappas
Georgios J
GJ
Ciampi
Ana Y
AY