Open AccessCrosses between sexual and apomictic dandelions ( Taraxacum ). II. The breakdown of apomixis
Author(s) -
Van Dijk Peter J.,
Tas Inge C. Q.,
Falque Matthieu,
BakxSchotman Tanja
Publication year - 1999
Publication title -
heredity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.441
H-Index - 118
eISSN - 1365-2540
pISSN - 0018-067X
DOI - 10.1046/j.1365-2540.1999.00620.x
Subject(s) - apomixis , biology , hybrid , ploidy , parthenogenesis , botany , egg cell , polyploid , asexual reproduction , genetics , embryo , gene , sperm
Some dandelions are diplosporous gametophytic apomicts. In order to study the inheritance and breakdown of apomixis, crosses were made between diploid sexuals and triploid apomicts. To investigate their breeding system, four nonapomictic diploid and 10 nonapomictic triploid hybrids were pollinated with diploids and the progenies were analysed. Seed fertility was significantly reduced in two diploid hybrids. Nine triploid hybrids were fertile and could be classified into three types, with respect to the composition of their progenies. Type A produced n + n hybrids. Type B produced either a mixture of n + n and 2 n + n hybrids, or a mixture of pseudogamous 2 n + 0 apomicts and 2 n + n hybrids. Type C produced exclusively 2 n + n hybrids. Inheritance of a microsatellite marker strongly suggested that 2 n egg cells in type C plants were produced by a first division restitution mechanism. As in apomicts, microsporogenesis in type C plants was reductional. This suggests that type C plants are diplosporous plants that lack parthenogenesis. Such plants are very rare in other apomictic plant species. It is concluded that ‘elements of apomixis’, diplospory and parthenogenesis, can be uncoupled. This is inconsistent with the single‐locus model for apomixis in Taraxacum as suggested by Mogie (1992). Instead, our results suggest that several loci are involved in the genetic control of apomixis in Taraxacum .