Theory and analysis of partial diallel crosses

Abstract

This study presents theory and analysis of partial diallel crosses based on Hayman's methods. This genetic design consists of crosses among two parental groups. It should be used when there are two groups of parents, for example, dent and flint maize inbred lines, and the breeder is not interested in the assessment of crosses between parents of the same group. Analyses are carried out using data from the parents and their F1 hybrids allowing a detailed characterization of the polygenic systems under study and the choice of parents for hybridization. Diallel analysis allows the estimation of genetic and non-genetic components of variation and genetic parameters and to assess the following: genetic variability in each group; genotypic differences between parents of distinct groups; if a parent has a common or a rare genotype in the group to which it does not belong; if there is dominance; if dominant genes increase or decrease trait expression (direction of dominance); average degree of dominance in each group; the relative importance of mean effects of genes and dominance in determining a trait; if, in each group, the allelic genes have the same frequency; if genes are equally frequent in the two groups; the group with the greatest frequency of favorable genes; the group in which dominant genes are most frequent; the relative number of dominant and recessive genes in each parent; if a parent has a common or a rare genotype in the group to which it belongs, and the genotypic differences between parents of the same group. An example with common bean varieties is considered.<br>Neste trabalho são apresentadas teoria e análise de dialelos parciais, com base nos métodos propostos por Hayman em 1954 e 1958. A análise dialélica com os dados dos pais e de seus híbridos F1 possibilita uma caracterização detalhada dos sistemas poligênicos sob estudo e a escolha de progenitores para hibridação. A partir da estimativa de componentes genéticos e não genéticos da variação e de parâmetros genéticos, a análise dialélica permite avaliar: a variabilidade genética em cada grupo; as diferenças genotípicas entre pais de grupos distintos; se um genitor tem genótipo comum ou raro no grupo ao qual não pertence; se há dominância; a direção de dominância; o grau médio de dominância em cada grupo; a importância relativa dos efeitos médios dos genes e dos desvios de dominância em determinar a característica; as freqüências de genes alélicos em cada grupo; se os genes são igualmente freqüentes nos dois grupos; o grupo em que os genes favoráveis estão em maior freqüência; o grupo em que os genes dominantes são mais freqüentes; o número relativo de genes dominantes e recessivos em cada pai; se um genitor tem genótipo comum ou raro em seu grupo, e as diferenças genotípicas entre os pais de um mesmo grupo

Using mating designs to uncover QTL and the genetic architecture of complex traits

“…The estimated variances were compared to the expected variances of GCA and SCA effects according to the theoretical decomposition of among-F 2 family variance. While different approaches have been developed for the analysis of diallel designs (Hayman, 1954a, b;Griffing, 1956;Gardner and Eberhart, 1966), partial diallels (Kempthorne and Curnow, 1961;eg Fyfe and Gilbert, 1963;Viana et al, 1999) and extensions of analysis to F 2 generations (Jinks, 1956;Hill et al, 2001), for the purposes of demonstration we follow the approach of Cockerham (1983) to obtain covariances among relatives derived by self-fertilization. All models were fit and tested in SAS (SAS Institute Cary, NC, USA).…”

Analysis of general and specific combining abilities of popcorn populations, including selfed parents

“…Hayman's method is the most complex to understand and to interpret, specifically for homozygous populations. Because of their potentials, these methodologies were adapted for partial diallels, with two groups of parents (Miranda Filho and Geraldi, 1984;Geraldi and Miranda Filho, 1988;Viana et al, 1999).…”

Genetic Studies on Grain Protein Content and Some Agronomic Characters of Rice by Halfdiallel Crossing System

“…The distance between plants was 25 x 25 cm, and between block 50 cm. Number of clump asThe data collections from the F1 and parent genotypes were analyzed using [8] approach modified by [6]. Analysis of variance was conducted to examine differences among genotypes, if there is a significant then it will further analyzed using diallel analysis, to estimate the additive and dominance gene effect with [9] approach.…”

“…Analysis of variance was conducted to examine differences among genotypes, if there is a significant then it will further analyzed using diallel analysis, to estimate the additive and dominance gene effect with [9] approach. The hypothesis of the presence of epistatic was tested using angular coefficient analysis as described by [10] and [6], was presented in [11] …”

“…This is useful to determine the effective selection method in the early generation of crosses [4]. Ones of the diallel crossing system is halfdiallel with all of F1 and the parent as the studied material [5][6]. The purpose of the research is to obtain genetic information on some agronomic characters and grain protein content in rice.…”