02905nam a2200241 a 450000100080000000500110000800800410001910000210006024501740008126000160025530000100027150001580028152021050043965000110254465000080255565000110256365000230257465000190259765300110261665300180262765300090264565300090265418571982011-04-06       2009    bl uuuu  m   00u1 u    #d1 aGARCIA, S. A. L.  aIdentificação, validação e uso de marcadores moleculares a partir de sequências de DNA dos genomas de Mycosphaerella fijiensis e de Musa spp.h[electronic resource]  a2009.c2009  a74 f.  aDissetação (Mestrado em Biotecnologia Vegetal) - Universidade Federal de Lavras, Lavras. Orientador Embrapa Agroenergia: Manoel Teixeira Souza Júnior.  aMycosphaerella fijiensis is the causal agent of black leaf streak of banana, the most important threat to banana production in many countries and particularly in Costa Rica where the climate is very conducive for the disease. Currently, the main control measure is the frequent application of fungicides. However, apart from environmental concerns, this approach is not sustainable due to the abrupt or gradual development of fungicide resistance. To analyze the population dynamics of fungicide resistance, we developed a molecular diagnostics for strobilurin resistance, using the cytochrome b gene (cytb), in M. fijiensis. We also developed molecular markers for the mating type idiomorphs (mat1-1 and mat1-2) and primers for five VNTR loci to estimate population genetic parameters. Monospore isolates were collected at three plantations that are 20-30 km apart (Cartagena, San Pablo and Zent) in the Limón province that represents the heart of the Costa Rican banana production area. Ninety-five isolates were obtained from a distant wild-type population that was never sprayed with fungicides in the Herédia province. In total, 665 isolates were assayed for mat1-1, mat1-2, VNTR and cytb. The mating type genes segregated in a 1:1 ratio indicating that the sampled populations most likely are randomly mating. The VNTR primers identified 32 alleles, among them, 21 were identified in wild type population, 20 in San Pablo population, 23 in Zent population and 24 in Cartegena population. The strobilurin diagnostic indicated that the wildtype population is entirely sensitive and that two of the three commercial populations, San Pablo and Cartagena are entirely resistant. The Zent population contained 8% of sensitive strains even though strobilurins were still used in that plantation. The next steps will be analysis of gene diversity within each population and the levels of gene flow. These analyses will provide an excellent basis for future research into fungicide resistance in Costa Rica populations of M. fijiensis as well as comparative analyses with other banana-producing areas.  aBanana  aDNA  aGenoma  aMarcador Molecular  aSigatoka Negra  aFungos  aTranscriptoma  aTrap  aVNTR