Análise da estrutura genética de populações e sistema reprodutivo de Oryza glumaepatula por meio de microssatélites / Genetic structure and mating system of Oryza glumaepatula steud. populations using microsatellite markers

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Informations about genetic structure and breeding systems are little and poorly of natural O. glumaepatula populations. The objective of this study was the characterization of the genetic structure of 11 populations from Japura, Solimoes, Purus, Negro, Xingu and Tapajos rivers (from Amazon Hidrographic Basin) and from Paraguai and Taquari rivers (from Paraguai Hidrographic Basin), sampling 30 individuals per population and analisys of breeding system of three populations SO-6, XI-1 and PG-1, from 10 mother progeny with 10 plants per progeny in each population. Individuals DNA were extracted quantified and analyzed utilizing eigth microsatellite loci with a mean of 10 alleles per loci. Genetic diversity parameters, Wright’s F-statistics and gene flow were stimated. Space structure was also verified using Pearson’s correlation coefficient (r) and Mantel’s test. The breeding system was examined by the apparent outcrossing rate (in the populations) and multilocus outcrossing rate obtained for the progenies of three populations.The following estimates of parameters were obtained: 77.3% polymorphic loci; Ho (observed heterozigosity) = 0.091; He (diversidade gênica) = 0.393; FST = 0.491 (e RST = 0.608); FIS = 0.780 e FIT = 0.888. Neither population was in Hardy-Weinber equilibrium. The average of apparent outcrossing rate was t a = 0.124, suggesting mixed mating system with predominance of inbreeding. One exception was the Xingu’s river population (XI-1), which have presented the lowest autogamy indices with ta = 0.459, Ho = 0.233, He = 0.369, and the lowest fixation index f = 0.371. These results pointed for a high genetic divesity between populations also variable natural inbreeding degrees. These populations were not structured on space, because were null the correlations between genetic and geographic distances (r = 0.003). The study of breeding system was based on lowest average alleles number per loci and to provide the following estimates for the three populations (XI-1, SO-6 e PG-1) respectively: average number of alleles per loci: 3, 3 and 5; maternal inbreeding ( ˆF m): 0.399, 0.846 and 0.631; multilocus outcrossing rate ( ˆt m): 0.160, 0.011 and 0.223; single-locus ( ˆt s): 0.078, 0.003 and 0.100; biparental inbreeding ( ˆt m - ˆt s): 0.083, 0.008 and 0.123; coancestry coefficient ( θfam): 0.711, 0.846 and 0.748. These results confirm the population desuniform mating system, which had varied from perfect autogamy to 22.3% of outcrossing rates. That desuniformity as well as the high interpopulation genetic diversity and the absence of space structuring indicate that conservation activities should include the largest possible number of populations.

ASSUNTO(S)

genetic structure reprodução vegetal molecular markers arroz genética vegetal breeding systems marcador molecular wild rice diversidade genética genetic diversity

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