Diversidade genética em progênies de milho doce utilizando marcadores SSR

• Autor(a) principal: Rupp, Jacinto Vagner
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/1383
• topic: Milho doce (Zea mays); Diversidade genética; Marcadores SSR (microsatélites); Brasil.; Sweet maize; Microsatellites; Genetic diversity; Brazil.; Ciências Agrárias; Agronomia

DNA Simple Sequences Repeated (SSR) primers, also known as microsatellites, previously isolated from common maize, were employed to select the most adequate one for the amplification of microsatellite sequences in the DNA of sweet maize, cultivars sugary-1 (su1). Amplification products inform the genetic diversity of the material under analysis, the genetic structure of developing progenies, populations and the distance and/or similarity between evaluated progenies. In the context of 100 primers, 13% were polymorphic (umc1071, umc1636, umc1736, umc1506, umc1582, umc1383, umc2080, umc1446, umc1590, umc1241, umc2343, umc1169, and umc2116) and used to investigate the genetic diversity in 15 strains of sweet maize (W-06, W-07, W-10, W-12, W-16, W-17.1, W-22, W-26, W-28, W-30, W-36, W-37, W-17.2, W-46, and W-49) through the determination of well-defined bands in gel and through the existence of different alleles. Primers umc2116 and umc1383 showed 2 and 3 alleles, respectively in 73.33% and 66.66% of strains; primer umc1582 was the least polymorphic. Excess of heterozygous genotypes in locus umc2116 has been pinpointed in strains W-12, W-28, W-26, W-46, W-30, and W-17.2. Frequency of alleles distributed according to Hardy-Weinberg equilibrium has been verified in 21.53% of tests in 15 progenies. W-26 had the highest number of polymorphic loci (92.31%) and the greatest number of alleles per polymorphic locus. Strain W-06 failed to present any polymorphism, whereas strains W-12, W-17.1 and W-10 had the least proportion of polymorphic loci SSR (23.08%). Strain W-46 had the highest proportion of heterozygous genotypes (Ho = 0.3385), while strain W-28 showed the highest proportion of expected heterozygous genotypes (He = 0.3368). Absence of polymorphism in 13 SSR loci of strain W-06 and high and low rates for the proportion of polymorphic loci and heterozygosity found and expected in the different strains determined a high genetic differentiation among the 15 su1 progenies in generation S5 (FST = 0.6515). It may be concluded that the selection process for the formation of the 15 sul strains of sweet maize has led towards the formation of highly differentiated strains for the analyzed 13 SSR loci. Positiveness for coefficient FIS indicates an excess of 4.36% of homozygous genotypes in S5 generation. Genetic divergence level shows the formation of three main groupings in which progenies are distributed in intervals of genetic similarities or identities (I) from 0.2085 to 0.8716. W-17.1 and W-26 are the most alike (I = 0.8716), whereas W-37 and W-49 are genetically the most divergent (I = 0.2085). Estimated rates for genetic identity among progenies may be useful for promising crossings, for the selection of interest characterization while keeping or amplifying the genetic diversity in the loci, as a rule neutral, such as SSR loci SSR.