, colchicine has been used to produce amphidiploid to recover fertility in these cultivars, enabling subsequent breeding experiments. The breeding methods of these novel poinsettia cultivars are described only in plant patent statements, which do not state the
Methods of producing 8x plants from 4x V. corymbosum clones through in vitro colchicine treatments were investigated. Colchicine concentrations and exposure times ranged from 0.001% to 0.2% and 1 to 14 days, respectively. Pretreatments designed to predispose the plants to the effect of colchicine also were investigated. Eleven 8x plants and one 4x-8x chimera were selected from pretreated plants exposed to 0.025% or 0.05% colchicine. The superior treatment was 0.025% with a 24- or 48-hr exposure time in liquid medium. No differences were noted between warm/dark and cold/dark pretreatments. No differences were observed among 24-, 48-, 96-, and 192-hr growth intervals between cold pretreatment and colchicine treatment. However, a significant genotype effect in response to colchicine was found, both with respect to culture survival and polyploid induction.
The mitotic inhibitors, colchicine and oryzalin, were evaluated for their effects on callus, adventitious shoot formation, and tetraploid induction of Euphorbia pulchurrima `Winter Rose'. In vitro grown leaf sections were placed on various media supplemented with either colchicine or oryzalin at various concentrations for 1 to 4 days. Colchicine was less damaging to leaf tissues than oryzalin. On various colchicine-containing media, prolific calluses were produced and adventitious shoot formation was observed. Regenerated shoots were found to be diploid as determined by flow cytometry. On media supplemented with oryzalin (28.9 μm to 144 μm), leaf tissues produced callus but failed to form adventitious shoots. Samples of calluses produced on oryzalin-containing media were subject to analysis using flow cytometry and were found to be diploid. These results suggest that the colchicine is less toxic on poinsettia tissues and shoot induction than oryzalin. Additional experiments are needed to establish a protocol for in vitro induction of poinsettia tetraploid with colchicine and oryzalin.
tetraploid hybrids from 1600 flowers pollinated along with an unknown number of triploids. The F 1 hybrids were fertile and were easily intercrossed and backcrossed to tetraploid northern highbush blueberry cultivars. Colchicine-derived tetraploids offer
colchicine and oryzalin ( Dhooghe et al., 2009 ; Pickens et al., 2006 ; Rey et al., 2002 ). Colchicine binds poorly to plant tubulins but has a high affinity for animal microtubulins and thus is toxic to humans ( Morejohn et al., 1987 ). By contrast
. Colchicine is the most widely used chemical agent for chromosome doubling. Tetraploids at frequencies of 83.3% and 80.0% were induced in Xanthosoma sagittifolium when in vitro-grown plants were treated with 1.25 m M or 2.5 m M of colchicine, respectively
compounds. Colchicine is an alkaloid obtained from Colchicum autumnale, which acts as a mitotic inhibitor ( Blakeslee and Avery, 1937 ) and induces tetraploidy in the target cells by interfering with spindle formation at the metaphase. Colchicine is
changes in chromosome number is well established ( Sajjad et al., 2013 ). Colchicine is a compound that effectively arrests mitosis at the anaphase stage, and it is widely used to induce polyploidy in plants ( Rego et al., 2011 ). The treatment of shoots
; Sparnaaij, 1979 ). Because naturally occurring polyploid genotypes are usually unavailable for breeding programs, polyploidy is typically induced through mitotic spindle inhibition or microtubule polymerization, often by exposure to colchicine ( Caperta et
interfering with cell division. A number of natural and synthetic compounds can be used and are either applied to plants ex vitro or in vitro. Colchicine is naturally occurring, and it was initially thought that it promoted polyploidy induction by disrupting