engleski

The use of trisomics in faba bean (Vicia faba L.) gene mapping

Trisomics of Vicia faba can be obtained from different sources such as polyploids, translocation stocks, and asynaptic mutants. The most successful way is proved to be by crossing an asynaptic line with a normal diploid parent. Five of possible six primary trisomics can be easily obtained and identified by showing modified morphology. Primary trisomics of V. faba are viable and sufficiently fertile to be used in genetic studies. Various critical ratios expected in an F2 population derived from selfed F1 trisomic plant can be calculated depending on (1) the type of gene (or marker) segregation, (2) the parent carrying the dominant allele, and (3) the trisomic segregation model. Trisomic critical ratios can be distinguished from the normal Mendelian ratios by means of chi-square test or trisomic LOD scoring. Based on F2 families derived from selfed F1 trisomic plants a genetic model to estimate linkage relationships between pairs of loci located on the extra chromosome is developed. Genotypic frequencies of each class expected in a trisomic F2 family can be calculated and the maximum likelihood equations for recombination fraction estimation can be derived for a variety of genetic situations. Thus, primary trisomics provide an excellent cytogenetic tool to localize genes of specific chromosomes, tot test the independence of linkage groups, and also to assign linkage groups to particular chromosomes. This approach is successfully used in a project with the aim of obtaining a detailed linkage map of faba bean genome.

Vicia faba L.; trisomics; gene mapping

nije evidentirano