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The Significance of Agamospermous Triploid Pollen Donors in the Sexual Relationships between Diploids and Triploids in Taraxacum (Compositae)
Author(s) -
Morita Tatsuyoshi,
Sterk Adri A.,
Nijs Joannes C. M.
Publication year - 1990
Publication title -
plant species biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 36
eISSN - 1442-1984
pISSN - 0913-557X
DOI - 10.1111/j.1442-1984.1990.tb00201.x
Subject(s) - polyploid , ploidy , biology , pollen , botany , sexual reproduction , hybrid , pollen tube , pollination , genetics , gene
We review in this article the investigations of the significance of agamospermous triploid pollen donors in the sexual relationships between diploids and triploids in Taraxacum . Crossing experiments between diploid sexual mother plants and agamospermous polyploid pollen donors and recent isozyme analyses of the progeny have exhibited the following results: 1) Pollen from Agamospermous polyploid pollen donors have the potential to give rise to the polyploid agamospermous offspring when fertilizing diploid sexual plants. Ploidy level of the progeny is usually the same or higher, but occasionally lower, compared to the pollen donor. 2) Diploid progeny also occur from diploid (♀)‐polyploid (♂) crosses, however, these diploids were in our results not hybrids but the results of self‐fertilization of the diploids. The self‐fertilization is regarded as a cosequence of the breakdown of the self‐incompatibility barrier through the sterile triploid's pollen. This breakdown is in all probability a common phenomenon in diploid (♀)‐polyploid (♂) crosses. Some examples suggest that agamospermous polyploids can increase their genetic diversity through obtaining genes from coexisting diploids. The evolutionary implications of this phenomenon and the reduction mechanism of chromosome number through agamospermous pollengenesis are discussed.