LINKED AND UNLINKED GENE INHERITANCE DURI NG AUTOSEGREGATION IN PARTHENOGENETIC PLANT PROGENIES

Theoretical models of linked and unlinked gene inheritance in partheno genetic progenies of diploid plants are considered, Attention is paid to the disomic type of gametic autosegregation, which is observed when meiocytes of diploid plants have a double (tetraploid) chromosome num ber, In this case, the general arrangement of homologous chromosome pa irs (chromatids) in meiosis is described by the formula of multiplicat ion of probabilities, and the distribution of individual homologous pa irs in tetrads of megaspores conforms to the hypergeometric formula of probability distribution. The disomic gametic autosegregation at more than one marker locus can be used to determine whether these markers are located on the same or different chromosomes, Four models of dihyb rid segregation are proposed, Genes located on the same chromosome wit h a recombination coefficient (r) of 0.5 follow the dihybrid patterns of segregation designated as models 1 and 2, which take into account t he phases of gene attraction and repulsion, The results of segregation are independent of the recombination chromosome length, Genes located on the same chromosome with r < 0.5 segregate according to the dihybr id pattern described by model 4, Genes located on different chromosome s follow the dihybrid pattern of segregation described by model 3, In the case of disomic gametic autosegregation, di-, tri-, and polyhybrid genotypic segregation ratios differ from those characteristic of zygo tic segregation, Gametic autosegregation of this type leads to homozyg otization of genotypes in the offspring: the inbreeding coefficient in a population increases by 42.86% per generation, which is more than t wo times greater than the corresponding increase obtained in crossings between sibs.