Development of microsatellite markers for genes related to defense responses in Musa acuminata
Banana (Musa spp.) is one of the world's most important monocotyledonous crops. As many of today's commercial cultivars are sterile triploids or diploids, with fruit development via parthenocarpy, restricted genetic variation has resulted in a crop lacking disease resistance. Considering the importance of molecular tools to accelerate development of disease resistant genotypes, the objective of this study was to develop microsatellite markers in Musa acuminata for unigenes related to defense and response to biotic stress. Microsatellites were mined in sequence data using the programs WebSat and SSRIT, with flanking primers designed using Primer3. Analyzed data containing genes potentially involved in defense or stress responses comprised unigene sequences for M. acuminata genotypes 'Calcutta 4' and Cavendish cultivar 'Grande Naine' (AAA genome, Cavendish subgroup), derived from 454 transcriptome pyrosequencing, NBS-LRR family resistance gene analog (RGA)-containing DNA BAC clone sequences from M. acuminata 'Calcutta 4', and NB-ARC conserved domain sequences in the M. acuminata DH Pahang whole genome sequence. A total of 156 SSR loci were validated for polymorphism by PCR in 20 M. acuminata genotypes organized into DNA bulks contrasting in resistance to black leaf streak and Sigatoka leaf spot. Primer annealing temperatures and MgCl2 concentrations were optimized and polymorphism examined on 4% polyacrylamide gels with silver nitrate staining. Currently, approximately 16% of loci display polymorphism. These loci have been tested against individualized bulks for identification alleles for each genotype. The microsatellites identified, associated with genes potentially involved in defense or stress responses, are potentially useful genetic markers for genotyping and genetic map construction for Musa segregating populations.
Miller, R.N.G., Emediato, F.L., Silva Jr., O. and Togawa, R. (2016). Development of microsatellite markers for genes related to defense responses in Musa acuminata. Acta Hortic. 1114, 91-94
biotic stress, Mycosphaerella musicola, transcriptome, 454 pyrosequencing, SSR