Browsing by Author "Diaz, Carole"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Genetic characterization of Japanese plum cultivars (Prunus salicina) using SSR and ISSR molecular markers
    (2012) Carrasco, Basilio; Diaz, Carole; Moya, Mario; Gebauer, Marlene; Garcia-Gonzalez, Rolando
    B. Carrasco, C. Diaz, M. Moya, M. Gebauer and R. Garcia-Gonzalez. 2012. Genetic characterization of Japanese plum cultivars (Prunus salicina) using SSR and ISSR molecular markers. Cien. Inv. Agr. 39(3): 533-543. The genetic characterization of 29 elite Japanese plum cultivars (Prunus salicina) and 4 Prunus cultivars was carried out by analyzing 97 Simple Sequence Repeat (SSR) alleles and 232 binary Inter Simple Sequence Repeat (ISSR) loci. A high level of genetic variability was found for these two molecular markers among the Japanese plum cultivars compared to other Prunus species. On average, the variability found by analyzing the SSR alleles were Na = 12.1, Ne = 5.2, Ho = 0.9, He = 0.8 and F = -0.127, whereas ISSR yielded values of h = 0.15 and I = 0.27. The genetic relationship among cultivars was estimated with Principal Coordinate Analysis (PCA) and a Bayesian clustering approach using the software program Structure. This program identified two subgroups (k=2). The first group included cultivars of four Prunus species: P. salicina, P. armeniaca, P. domestica and P. ceracifera, whose memberships ranged between 0.74 and 1.0. The second group included 19 Japanese plum cultivars and one plumcot cultivar, with memberships between 0.57 and 0.99. With some exceptions, similar relationships among cultivars were foundPCA. The level of genetic differentiation between two groups was low (G(st)=0.055 and phi(ST)=0.04), and a low level of linkage disequilibrium (LD) was observed for all allele combinations. These results suggest that the high level of genetic variability, the low level of LD and the scarce degree of differentiation detected by Structure between the two genetic groups can be explained by the self-incompatibility mechanism that favors the exchange between genetically distant Prunus cultivars and by the intra- and interspecific hybridization strategies frequently used in plum breeding programs.
  • No Thumbnail Available
    Item
    Heterogeneous genetic structure in a natural population of Rauli (Nothofagus nervosa)
    (2011) Carrasco, Basilio; Eaton, Lafayette; Letelier, Luis; Diaz, Carole; Garcia-Gonzales, Rolando
    B. Carrasco, L. Eaton, L. Letelier, C. Diaz, and R. Garcia-Gonzales. 2011. Heterogeneous genetic structure in a natural population of Rauli (Nothofagus nervosa). Cien. Inv. Agr. 38(3): 441-452. Heterozygote deficiencies in natural populations of outbreeding tree species are common and thought to be due mainly to biparental inbreeding. Inbreeding is believed to be caused by family structure within populations, a product of limited seed dispersal and probably limited pollen dispersal. Although both theory and simulation studies predict that structure should be apparent where trees are isolated by distance, most studies of structure in natural populations have detected only a weak spatial genetic structuring. In this contribution, we compare the use of spatial autocorrelation methodology and F statistics with the concept of relatedness to examine the spatial genetic structure in the natural population of a native southern beech and to explore the discrepancy between theory and observations. Autocorrelation detected structure in only a few of the nine enzyme loci tested in an estimated patch size of approximately 10 m. By successively eliminating the largest distances in the Gabriel map, the population was separated into groups or patches of neighbors, which were then tested for relatedness. Three groups of relatives were found interspersed with seven groups of unrelated individuals. The F statistics for these groups also showed weak genetic structure. We suggest that heterogeneity of family structure within natural populations may be one reason why more spatial genetic structure has not been detected.