Isozyme polymorphism and genetic differentiation in natural populations of an endemic tetraploid species <Emphasis Type="Italic">Avena maroccana</Emphasis> in Morocco |
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Authors: | Toshinobu Morikawa J Mike Leggett |
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Institution: | (1) Laboratory of Genetics and Plant Breeding, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai Osaka, 599-8531, Japan;(2) Institute of Grass Land and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK |
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Abstract: | A wild tetraploid oat Avena maroccana Gdgr. was collected from the 11 populations in the periphery of Rommani and Casablanca geographic groups of Morocco. Genetic
diversity of the species was investigated using six allozyme systems. Allelic frequencies were scored representing eight polymorphic
and five monomorphic loci. Coefficient of gene differentiation (Gst) was 0.3019, which indicated great genetic differentiation. The number of alleles per locus was 2.6154, the percentage of
polymorphic loci was 61.54, and the expected heterozygosity was 0.2462 in all populations. Genetic diversity in A. maroccana was high in comparison to self-pollinated species. In total, nine heterozygotes resulting from outcrossing were found in
the progeny from M1, M3, M4, M22 and M26. The population of M7 had peculiar alleles Pgd–2SS and Pgd-1SS in high frequency. M9 had the lowest level of diversity out of the 11 populations. Geographic and genetic distances between
all the populations were not significantly correlated with each other (r = 0.0996). Cluster analysis showed that two groups, (M1, M22, M2 and M4) and (M3, M23, M8, M5 and M26) were apparently differentiated.
Two populations of the Casablanca group, M7 and M9 were independent from each other, and were separated distinctly from the
other populations. Genetic diversity of the Rommani and Casablanca groups was almost the same in all the parameters. This
was due to the similar man-made habitat such as roadside or rich fertile soil and brown clay soils. The population size of
A. maroccana was small and restricted to the narrow central Morocco with great genetic differentiation so that genetic diversity may be
reflected from the results of genetic drift and outcrossing heterozygote segregation. |
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Keywords: | Avena maroccana Genetic differentiation Genetic diversity Isozyme Oat Plant germplasm |
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