XXIIIrd International Eucarpia symposium, Section Ornamentals ...

INHERITANCE OF 2N GAMETES FORMATION
IN A F1 AND F2 POPULATION OF BEGONIA
HYBRIDS
In Begonia several 2n producing genotypes exist. Among these, Begonia ‘Orococo’,
produces a high number of first division restitution (FDR) pollen as was shown by the
formation of mainly diads during microsporogenesis. Crosses with B. ‘Orococo’ as father
plant and B. soli-mutata, B. ‘Art Hodes’ and B. ‘Orococo’ as mother plants resulted in a
total of 306 seedlings, of which 295 were triploid and only 11 diploid. In the reciprocal
cross with B. ‘Orococo’ as mother plant and B. soli-mutata as father plant 50 diploids and
only 3 triploids were detected, indicating that B. ‘Orococo’ produces also unreduced egg
cells but in lower frequencies compared to unreduced pollen. In order to study the
inheritance of 2n pollen formation, both pollen size and microsporogenesis aberrations in
50 triploid and 29 diploid F1 seedling were investigated. In all triploid seedlings monads
or diads were observed. In several cases, also a high number of polyads were present.
However the frequency such pollen was observed varied significantly between individual
seedling. As a result, all seedlings produced large (2n) or only bad sterile pollen. None of
them produced only normal pollen without 2n pollen. In contrast, only 13 of the 29
investigated diploid seedlings produced monads or diads. Six of these seedling
produced no pollen mother cells at all. As a result, only a part of the diploid seedlings
produced large 2n pollen, while several other seedlings produced only normal pollen or
no pollen at all. The germination capacity of the F1 pollen was in general poor, although
in some cases germination percentages reached above 20%. Some F1 triploids were
used to produce tetraploid F2 progeny. A total number of 14 seedlings was obtained. Of
the 8 investigated tetraploids, 6 produced monads or diads. The obtained results show
that the heritability of 2n pollen production is very high.
P22
Angelo Dewitte (1)
Johan Van
Huylenbroeck (2)
Erik Van Bockstaele
(2,3)
(1) KATHO,Dept. HIVB,
Wilgenstraat 32, 8800
Roeselare, Belgium
(2) Inst. for Agricultural and
Fisheries Research (ILVO),
Plant Sciences unit,
Applied Genetics and
Breeding, Caritasstraat 21,
9090 Melle, Belgium
(3) Ghent University,
Faculty of Bioscience
Engineering, Dept. for Plant
Production, Coupure links
653, 9000 Gent, Belgium
johan.vanhuylenbroeck@
ilvo.vlaanderen.be
Session Posters 95