Complex Segregation Analysis (Csa) of Gerbera Flower Color

Abstract

<jats:p>The frequency distribution of gerbera flower hue in the Davis population of gerbera appears continuous and bimodal. This suggests that a gene of large effect may be segregating in a background of polygenic variation. CSA is a statistical technique developed in genetic epidemiology for investigating such complex traits without the need of inbred lines. The REGC program of SAGE (Elston, LSU Medical Center, New Orleans) uses the regressive models of G. Bonney (1984) through pedigree analysis to provide estimates of major gene parameters and residual correlations among relatives. Pedigrees obtained from generations 14, 15, and 16 indicate that a major dominant gene for hue is segregating and accounting for -0.66 of the total variation. The genotypic means are 32 degrees and 71 degrees for the <jats:italic>aa</jats:italic> and <jats:italic>bb</jats:italic> genotypes, respectively. The a allele is dominant to the <jats:italic>b</jats:italic> allele and has a frequency of 0.55. The residual parent-offspring correlation estimate is 0.2 and measures the genetic contribution to the remainder of the variance.</jats:p>

Complex segregation analysis of day-neutrality in domestic strawberry (Fragaria ×ananassa Duch.)

“…software (2004). The technique has been widely applied in human and animal research (e.g., Cargill et al, 2004) and in plants (Tourjee et al, 1995). For our experiment, three explanatory models were compared for each variable: (1) Polygenic inheritance with environmental effects (i.e., no major locus), (2) a Mendelian locus with complete dominance for day-neutrality in combination with polygenic and environmental variation, and (3) a single Mendelian locus with partial dominance for day-neutrality together with polygenic and environmental variation.…”

Heterogeneity of Segregation Ratios from Selfed Progenies Demonstrate Polygenic Inheritance for Day Neutrality in Strawberry (Fragaria ×ananassa Duch.)

“…Furthermore, the detection of substantial differences among progenies for quantitative measures of fl ower production in their day-neutral offspring suggests that the fl owering response is highly complex and future focus on segregation ratios rather than the fl owering variables themselves may be misplaced. From a pragmatic perspective, the goal might be to fi rst set appropriate targets for genetic improvement in terms of late-summer infl orescence numbers or fruit production parameters, then use more trait-based methods, such as complex segregation analysis (Tourjee et al, 1995) to quantify the relevant variation. Table 3.…”

Análise genética da resistência à antracnose foliar em milho.

“…Há alguns relatos de análises que utilizam modelos de misturas em populações humanas e animais (Elston & Stewart, 1973;Morton & MacLean, 1974;Knott et al, 1991;Le Roy et al, 1990;Janss et al, 1995;Shoukri & McLachlan, 1994). Métodos similares que utilizam a máxima verossimilhança também foram desenvolvidos para analisar locos maiores em gerações segregantes derivadas de cruzamento entre linhagens endogâmicas de plantas (Tourjee et al, 1995;Loisel et al, 1994;Jiang et al, 1994). Geralmente, as estimativas de máxima verossimilhança dos parâmetros são obtidas utilizandose o algoritmo EM (Dempster et al, 1977), que alterna passos de esperança e maximização.…”