The backcross analysis of complex gametophytic complementary S gene systems in diploid angiosperms

摘要

Conventional diallel schemes of pollination between sibs in F1 or I1, families rapidly become unduly difficult to handle in the genetic analysis of complex gametophytic S gene mechanisms. In order to promote research into these mechanisms, their distribution, genetic architecture and mode of team cooperation, a two-step backcross scheme has been elaborated, in which an F1, plant is backcrossed with pollen from its maternal parent. This scheme considers (1) the frequency with which a particular S gene constellation segregates in this F1 plant, and (2) the range of S gene constellations segregating in its maternal parent. Complications in the backcross scheme may arise, which are caused by (1) S genes shared by the two original plants and transmitted to the F1 plant, (2) homozygous S loci occurring in the maternal parent, (3) linkage of S loci, (4) selective fertilization. The complete combinatory scheme, for S gene systems of various degrees of complexity, is presented for overcoming these difficulties in the consideration of the combined set of data in a two-step backcross analysis of complex gametophytic complementary S gene systems in diploid angiosperms.