Chromosome doubling in a Rosa rugosa Thunb. hybrid by exposure of in vitro nodes to oryzalin: the effects of node length, oryzalin concentration and exposure time

Abstract

Chromosome doubling was induced in vitro in a diploid hybrid of Rosa rugosa Thunb. using oryzalin as the spindle inhibitor. Nodal sections, 2 mm long, were exposed to 2.5 or 5 microM oryzalin and 10 mm nodal sections were exposed to 5 microM oryzalin for 0 (controls), 6, 12, 24 and 48 h. The ploidy of the emergent shoots was determined by flow cytometry. The frequency of tetraploid and mixoploid leaves that developed from 2 mm nodal sections exposed to 5 microM oryzalin peaked at 12 h exposure, when 35% of the leaves were tetraploid, but fell after longer exposures. Fewer tetraploid and mixoploid leaves were found when 2 mm nodes were exposed to 2.5 microM oryzalin for 6 and 12 h, indicating that it took longer for a spindle inhibiting concentration of oryzalin to build up in the meristem. However, the frequencies of tetraploid and mixoploid leaves continued to rise after 12 h and were highest at 48 h, when 44% were tetraploid. In treatments with 5 microM oryzalin, the frequencies of tetraploid and mixoploid leaves were lower, at equivalent exposure times, in 10 mm nodes than 2 mm nodes. This suggests that oryzalin diffused to the meristem mainly via the cut surfaces and that access via the epidermis and cuticle was impeded.

Phenotypic and genome size changes (variation) in synthetic tetraploids of daylily (Hemerocallis) in relation to their diploid counterparts

“…Although, in our daylily tetraploids the stomata, leaves, and flowers were larger, the bud number per scape was lower in both cultivars, and the stem length, depending on cultivar, was similar or lower compared to diploids. Negative correlation associated with tetraploidisation was also noted in Rosa rugosa for the number of flowers per inflorescence (Allum et al 2007) as well as the number of flowers per plant and the stem length in Vicia villosa (Elradi and Unal 2010). Reduction in plant height was noted for some fruit plants such as cherry rootstock (Webster 1996) and citrus hybrid trees (Jaskani and Khan 2000).…”

Inducing autotetraploids in cassava using oryzalin and colchicine and their in vitro morphophysiological effects

“…However, other authors report that liquid medium could successfully be adopted for multiplication of potato seedlings Fortes, 2003, 2004), banana (de Siqueira et al, 2013), and pineapple (Barboza et al, 2009). Regarding the successful generation of autopolyploid plants, Allum et al (2007) reported that the combination of high antimitotic doses and long exposure times can double the DNA content, resulting in high ploidy levels and the generation of several mixoploids. Therefore, it is important to evaluate cultivation under different exposure times and antimitotic concentrations of cassava apical and lateral explants because these conditions might vary for each species and type of material used (Pereira et al, 2012).…”

“…Polyploidy can be induced using antimitotics, such as colchicine and oryzalin (Allum et al, 2007;Ascough and Van Staden, 2008;Rêgo et al, 2011). Colchicine is the most widely used and successful antimitotic (Ishigaki et al, 2009;Quesenberry et al, 2010;Souza-Kaneshima et al, 2010).…”

Colchicine and oryzalin effects on tetraploid induction and leaf anatomy of Solanum commersonii ssp.

“…The bud bursts originated from one or a few cells of the meristematic tissue results in a low frequency of chimeric plant regeneration since the exposure time as well as type and concentration of the antimitotic substance used for chromosome duplication was previously adjusted (LATADO et al, 2007). In addition, ALLUM et al (2007) reported that oryzalin diffuses better into the meristematic tissue through the cut (which was made in the explant during micropropagation) than through the epidermis or cuticle (which seems to prevent the substance from entering). This may have favored polyploidization via tissue culture.…”

“…This may have favored the occurrence of tetraploidy in the SCM 60 genotype (Table 1). Oryzalin has shown to be effective in the chromosome duplication in roses (ALLUM et al, 2007), and other fruit and ornamental plants (DHOOGHE et al, 2011).…”