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Identification, characterization and mapping of EST-derived SSRs from the cacao-Ceratocystis cacaofunesta interaction

Ferreira Santos R.M., Clément D., Santos Lima L., Legravre T., Lanaud C., Schnell R.J., Pires J.L., Lopes U.V., Micheli F., Gramacho K.P.. 2013. Tree Genetics and Genomes, 9 (1) : p. 117-127.

Ceratocystis cacaofunesta is an ascomycete responsible for the lethal wilt disease of cacao (Theobroma cacao L.). Marker-assisted selection combined with conventional breeding is one powerful approach to improve cacao resistance to Ceratocystis wilt. In this study we screened a set of ESTs obtained from cacao elicited with C. cacaofunesta to identify EST-SSRs and test their efficacy for mapping. Among the 3,432 ESTs analysed, 384 contained SSRs and 428 EST-SSRs were identified, mainly dinucleotides (78.5 %), with four repeats (75.23 %), and preferentially AG/CT motif (25.47 %). Gene ontology function was assigned to the ESTs containing SSRs: 4.04 % belonged to "defense response" category, with 20.69 % of them to the sub-category "defense response to fungi". In relation to the ORF, the same quantity of EST-SSRs was observed in the 5? UTR, ORF and the 3? UTR (about 30 %). From the 428 EST-SSRs identified, 12 were polymorphic, revealing a total of 41 alleles. The number of alleles per locus ranged from 2 to 6, with an average of 3.41. Four EST-SSRs were mapped on the F2 Sca 6 × ICS 1 population segregating for Ceratocystis wilt, and were distributed on the 2, 3, 4 and 8 linkage groups. These markers will have potential applications in linkage mapping and will be valuable for the research community to improve the cacao breeding program. (Résumé d'auteur)

Mots-clés : génétique moléculaire; résistance génétique; résistance aux maladies; marqueur génétique; polymorphisme génétique; carte génétique; identification; theobroma cacao; ceratocystis; trinité-et-tobago; colombie; pérou; guyane française; Équateur; venezuela (république bolivarienne du); brésil; ceratocystis cacaofunesta; ssr

Thématique : Maladies des plantes

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