TY - JOUR
T1 - Crosses between sexual and apomictic dandelions (Taraxacum). II. The breakdown of apomixis
AU - Van Dijk, P.J.
AU - Tas, I.C.Q.
AU - Falque, M.
AU - Bakx-Schotman, Tanja
N1 - Reporting year: 1999
Metis note: 2300; CTE; PVP ; TE file:///L:/Endnotedatabases/NIOOPUB/pdfs/Pdfs1999/VanDijk_ea_2300.pdf
PY - 1999
Y1 - 1999
N2 - 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 2n + n hybrids, or a mixture of pseudogamous 2n + 0 apomicts and 2n + n hybrids. Type C produced exclusively 2n + n hybrids. Inheritance of a microsatellite marker strongly suggested that 2n 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. [KEYWORDS: 2n-gametes; apomixis; diplospory; parthenogenesis; pseudogamy;Taraxacum Fertilization]
AB - 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 2n + n hybrids, or a mixture of pseudogamous 2n + 0 apomicts and 2n + n hybrids. Type C produced exclusively 2n + n hybrids. Inheritance of a microsatellite marker strongly suggested that 2n 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. [KEYWORDS: 2n-gametes; apomixis; diplospory; parthenogenesis; pseudogamy;Taraxacum Fertilization]
U2 - 10.1038/sj.hdy.6886200
DO - 10.1038/sj.hdy.6886200
M3 - Article
SN - 0018-067X
VL - 83
SP - 715
EP - 721
JO - Heredity
JF - Heredity
ER -