Articles
IN VITRO ASSISTED BREEDING OF EVERGREEN AZALEA AS A TOOL FOR ASSORTMENT EXTENSION
Article number
829_6
Pages
55 – 60
Language
English
Abstract
Rhododendron simsii Planch. hybrids (Belgian pot azaleas) constitute an ornamental plant group of major economic importance.
An extended breeding project at ILVO has been running for several decades.
New in vitro culture protocols were developed in order to increase genetic variation and to obtain interesting pre-breeding products.
Based on adventitious shoot formation on in vitro leaflets, sport formation was induced in several cultivars.
In some diploid cultivars carrying broad-edged flowers, petal margins were found to be tetraploid.
From the tetraploid tissues of these picotee chimeras, polyploid plantlets were obtained through this regeneration protocol.
Alternative strategies for polyploidy induction in vitro, through mitosis-arresting chemicals, are elaborated, starting from seed or stock cultures.
The obtained polyploids, in turn, were used to generate higher ploidy levels due to their production of unreduced gametes.
Immature embryos harvested after interspecific crosses between evergreen pot azalea and other Rhododendron types were cultured for embryo rescue.
The growth of several interspecific hybrids was sustained through to successful acclimatization, thanks to the incorporation of multiple in vitro steps.
As polyploid induction and embryo rescue protocols hold promise for sport regeneration, enlargement of the commercial assortment in evergreen Belgian pot azalea is anticipated.
In the future, even more opportunities lay at hand for evergreen azalea breeding.
Suitable regeneration systems for haploid cells and transformed tissues may further widen the possibilities for in vitro assisted breeding in this crop.
An extended breeding project at ILVO has been running for several decades.
New in vitro culture protocols were developed in order to increase genetic variation and to obtain interesting pre-breeding products.
Based on adventitious shoot formation on in vitro leaflets, sport formation was induced in several cultivars.
In some diploid cultivars carrying broad-edged flowers, petal margins were found to be tetraploid.
From the tetraploid tissues of these picotee chimeras, polyploid plantlets were obtained through this regeneration protocol.
Alternative strategies for polyploidy induction in vitro, through mitosis-arresting chemicals, are elaborated, starting from seed or stock cultures.
The obtained polyploids, in turn, were used to generate higher ploidy levels due to their production of unreduced gametes.
Immature embryos harvested after interspecific crosses between evergreen pot azalea and other Rhododendron types were cultured for embryo rescue.
The growth of several interspecific hybrids was sustained through to successful acclimatization, thanks to the incorporation of multiple in vitro steps.
As polyploid induction and embryo rescue protocols hold promise for sport regeneration, enlargement of the commercial assortment in evergreen Belgian pot azalea is anticipated.
In the future, even more opportunities lay at hand for evergreen azalea breeding.
Suitable regeneration systems for haploid cells and transformed tissues may further widen the possibilities for in vitro assisted breeding in this crop.
Authors
T. Eeckhaut, E. De Keyser, J. Van Huylenbroeck
Keywords
interspecific hybrids, polyploids, Rhododendron, sport regeneration, unreduced gametes
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