Mechanisms and genetic control of interspecific crossing barriers in Lycopersicon. Final report

摘要

Deficiency of Lycopersicon esculentum allele (E) was observed from the RFLP and isozyme data of the F(sub 2) populations derived from the cross L. esculentum x L. pennellii. The genome composition of the F(sub 2) populations containing L. pennellii cytoplasm (F(sub 2)(sup Lp4)) has a lower proportion of the homozygous L. pennellii (PP) genotypes and a higher proportion of heterozygote (EP) genotypes than that of the F(sub 2) populations containing L. esculentum cytoplasm (F(sub 2)(sup Le)). A lower proportion of the L. pennellii alleles (P) was also observed in F(sub 2)(sup Lp4) as compared to F(sub 2)(sup Le) when each marker locus was tested individually. To study the effects of gametic and zygotic selection on segregation distortion, the expected patterns of segregation at a marker locus were derived for ten selection models with gametic or zygotic selection at a hidden linked locus. Segregation distortion caused by four of the selection models studied can be uniquely identified by the patterns of significance expected for the likelihood ratio tests at the marker loci. Comparison of the chromosomal regions associated with specific selection models across populations (of this experiment and previous publications) indicated that the segregation distortion observed in chromosome 10 is associated with zygotic selection affecting both arms of the chromosome, and cytoplasm substitution has the effect of decreasing the segregation distortion on the long arm of the chromosome.