Isozyme Polymorphism and Genetic Differentiation in Natural Populations of a New Tetraploid Species Avena agadiriana, from Morocco

Abstract

A new wild tetraploid oat Avena agadiriana Baum et Fedak was collected from the five populations along the Atlantic coast in Morocco. Variations in six enzyme systems were surveyed and allele frequency, percentage of polymorphic loci, number of alleles per locus, observed and expected heterozygosities, and unbiased genetic distance were calculated. Phenotypic frequencies were scored representing 11 polymorphic loci. The mean percentage of polymorphic loci was 46.25, the mean number of alleles per locus was 1.502, and the mean expected heterozygosity was 0.1526. Two heterozygotes resulting from outcrosses were found in the progeny from M60 and M71. The population of M71 had peculiar alleles Est-4A not present in the other populations. Most of the genetic diversity of this species was between populations with little existing within populations. Geographic and genetic distances between populations were positively correlated with each other and the correlation coefficient was 0.7031. Cluster analysis showed two strongly differentiated groups were apparent, M71 and M74, and the remainder. The former group appears to be adapted to man-made habitat, such as road side or eucalyptus plantation, and the latter to a distinct dry, sandy habitat. To make wide intra-specific variation in this species, the modified mating system would be indispensable.

Isozyme polymorphism and genetic differentiation in natural populations of an endemic tetraploid species Avena maroccana in Morocco

“…The unbiased heterozygosity expected by the HardyWeinberg's equilibrium in the A. maroccana populations was 0.2462. This value is also intermediate between the mean values for the Avena species A. canariensis (0.2545) and A. agadiriana (0.2403) recalculated by using data of Leggett (1990 and2005), and much higher than A. fatua (0.06) and A. barbata (0.03) reported by Marshall and Allard (1970). The outcrossing rate and heterozygosity of A. maroccana were higher than those of the regional and widespread Avena species.…”

“…Variability among populations within geographic grouping would not be negligible as reported in red clover (Mosjidis et al 2004). Similarly, the range of variation within populations in electrophoretic traits of an endemic species A. maroccana was greater than the variation found in reginal species, A. agadiriana (Morikawa and Leggett 2005). However, the genetic variability between the two Rommani and Casablanca groups was almost the same.…”

“…It is higher than those of the Californian populations of A. barbata Pott. ex Link (0.1-7%, Marshal and Allard 1970), the Canary Island's populations of A. canariensis (0%, Morikawa and Leggett 1990) and the Moroccan populations of A. agadiriana (1.259%, which was recalculated from multiple loci data of Morikawa and Leggett 2005). The unbiased heterozygosity expected by the HardyWeinberg's equilibrium in the A. maroccana populations was 0.2462.…”

“…(2n = 2x = 14) from two of the Canary Islands Fuerteventura and Lanzarote, and reported that the northern part of Lanzarote included quite peculiar genetic variations. Morikawa and Leggett (2005) also examined that the isozyme variations of A. agadiriana Baum et Fedak (2n = 4x = 28) which was distributed a more widely along the Atlantic coast of Morocco. In A. agadiriana, ecotypic variants were observed and mating system was differentiated.…”

Phylogenetic Relationships of Tetraploid AB-Genome Avena Species Evaluated by Means of Cytogenetic (C-Banding and FISH) and RAPD Analyses

“…Combining of our results allow us to suggest that A. agadiriana displays the broadest intraspecific polymorphism. This species is known to fall into two geographic groups-Northern and Southern [38,45]. Cbanding analysis also revealed two chromosomal types in A. agadiriana which differ from each other by five out of fourteen chromosome pairs (2A, 4A, 7A, 9B and 14B).…”