Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/14/2009
Publication Date: 9/10/2009
Citation: Sun, Q., Sun, H., Li, L., Bell, R.L. 2009. In vitro colchicine-induced polyploid plantlet production and regeneration from leaf explants of the diploid pear (Pyrus communis L.) cultivar, 'Fertility'. Journal of Horticultural Science and Biotechnology. 84(5):548-552.
Interpretive Summary: Polyploid plants, plants containing more than the usual diploid two sets of chromosomes, have sometimes been used to breed new cultivars. In fruit crops, polyploid plants are frequently characterized by vigorous trees, large fruit size, and good quality. Tetraploid (four sets) and triploid (three sets) pome fruits have become important in production. Most of these existing polyploid plants were selected from spontaneous mutations of seedlings or clones, but the spontaneous mutation frequency is very low. Therefore, artificially induced polyploid mutation should be beneficial. Plant tissue culture has a potential for improving the effectiveness of mutation induction, because it offers a wide choice of plant material for treatment that is more suited to induction techniques compared to buds. Artificial polyploid induction with colchicine has been successfully achieved in many fruits species, but all of these polyploids were obtained either from shoot tips, micropropagated shoots cultivated on medium containing colchicine, or from embryos or protoplasts. Polyploid plants directly induced during shoot regeneration from leaf tissue have not been reported. In this research, polyploid plants were induced using colchicine at a frequency of 1 - 7% after 24 – 72 hours of treatment with 48 hours being optimal. The research demonstrated the potential of treatment of leaf tissue during plantlet regeneration as an improved method of generating polyploidy pear plants.
Technical Abstract: Polyploid plantlets, including triploid, tetraploid and other polyploids, were induced from in vitro leaves of a European pear (Pyrus communis L.) cultivar 'Fertility' by a colchicine treatment. In vitro leaves were incubated in 0.4% colchicine solution for 24, 48 or 72 h, and transferred to an adventitious shoot induction medium. Regenerated shoots were pre-selected according to morphological characteristics compared with a control shoot. The shoots with polyploid morphological characteristics were maintained and proliferated. The ploidy level of putative polyploid individuals was identified by chromosome counting. Polyploid shoots were rooted and transferred to the field. Polyploid plantlets had higher specific leaf mass and larger stomata than those of original diploid plantlets.