Articles
POLYPLOIDY AND VARIETY IMPROVEMENT OF PHALAENOPSIS ORCHIDS
Article number
878_14
Pages
133 – 138
Language
English
Abstract
Polyploidy played an important role in the development of Phalaenopsis varieties.
Many popular commercial hybrids are tetraploids.
However, analysis of the pedigree of these hybrids indicated that their genetic base was quite narrow.
On the other hand, it is difficult to transfer favorable genes of the diploid wild species to the commercial hybrids because of the difference in the ploidy levels.
In addition, the chromosome sizes of Phalaenopsis species varied tremendously.
Hybrids developed from the crosses between these species were usually sterile due to the problem of genome homology.
Chromosome doubling is one of the methods to restore the fertility of these hybrids.
Due to the above reasons, a research project was initiated in 2004 to develop simple and effective methods to detect the nuclear DNA content by flow cytometry and to double the chromosome of Phalaenopsis species and varieties by the use of tissue culture without application of anti-microtubule agents.
The nuclear DNA contents of the native species and some of the related hybrids of Phalaenopsis in several germplasm banks and orchid nurseries in Taiwan were determined.
Based on this information, Phalaenopsis species were grouped into low, medium and high nuclear DNA content which reflects the chromosome sizes of the species.
This will provide useful information to orchid breeders for the selection of parental varieties for hybridization.
Through chromosome doubling techniques, a conversion program to develop a series of tetraploid native species of Phalaenopsis is in progress.
This project will provide a wide range of tetraploid germplasm matching the ploidy level of the commercial hybrids to accelerate the breeding of novel varieties of Phalaenopsis for the market and to create a significant impact on the orchid industry in the coming years.
Many popular commercial hybrids are tetraploids.
However, analysis of the pedigree of these hybrids indicated that their genetic base was quite narrow.
On the other hand, it is difficult to transfer favorable genes of the diploid wild species to the commercial hybrids because of the difference in the ploidy levels.
In addition, the chromosome sizes of Phalaenopsis species varied tremendously.
Hybrids developed from the crosses between these species were usually sterile due to the problem of genome homology.
Chromosome doubling is one of the methods to restore the fertility of these hybrids.
Due to the above reasons, a research project was initiated in 2004 to develop simple and effective methods to detect the nuclear DNA content by flow cytometry and to double the chromosome of Phalaenopsis species and varieties by the use of tissue culture without application of anti-microtubule agents.
The nuclear DNA contents of the native species and some of the related hybrids of Phalaenopsis in several germplasm banks and orchid nurseries in Taiwan were determined.
Based on this information, Phalaenopsis species were grouped into low, medium and high nuclear DNA content which reflects the chromosome sizes of the species.
This will provide useful information to orchid breeders for the selection of parental varieties for hybridization.
Through chromosome doubling techniques, a conversion program to develop a series of tetraploid native species of Phalaenopsis is in progress.
This project will provide a wide range of tetraploid germplasm matching the ploidy level of the commercial hybrids to accelerate the breeding of novel varieties of Phalaenopsis for the market and to create a significant impact on the orchid industry in the coming years.
Publication
Authors
W.H. Chen, C.Y. Tang, Y.L. Kao
Keywords
chromosome doubling, variety improvement, breeding, DNA, germplasm development
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