diploid. Doubling of the chromosomes of haploid plants using chemicals or spontaneously is called dihaploidization. Some chemicals such as colchicine are used for chromosome doubling. These chemicals have certain disadvantages: 1) the chemicals are both
(allotetraploid). Chromosome doubling has also been used to develop fertile allotetraploid forms of the hybrids Lilium henryi × L. candidum ( van Tuyl et al., 1992 ), Passiflora incarnata L. × P. edulis f. flavicarpa ( Knight, 1991 ), and the kangaroo
79.9% ( Chavez, 2008 ). Fertile high-vigor amphidiploids are expected from crosses between tetraploid plants of the two species. These plants could be used as ornamentals. Cytogenetic studies. Chromosome doubling by colchicine was confirmed by
Hibiscus moscheutos L. is an herbaceous hibiscus native to eastern North America that has been a popular landscape and container plant exhibiting large and colorful flowers in the summer. However, unsightly fruit develop and remain on the stalks at the end of the blooming season, which greatly decreases the ornamental value. Thus, breeding for sterility was attempted through ploidy level manipulation to reduce formation and growth of seed stalks, and to improve blooming vigor and longevity. Colchicine and oryzalin were used as mitotic inhibitors to induce tetraploid breeding lines that could be used to develop sterile triploids. Germinated seedlings of ‘Luna Red’ were soaked in three concentrations of each doubling agent for three different durations. Exposure to a low concentration of colchicine solution for a long time or to a low concentration of oryzalin for a short period was found to be effective in yielding a high number of tetraploids with a low rate of mortality. Triploids were obtained from the traditional method of crossing tetraploids with diploids. Triploid and tetraploid plants showed a decrease in height with a more compact form. Leaves of tetraploid plants were more ruffled, with an increase in overall leaf thickness, but were not different from leaves of diploids and triploids in regard to leaf mass per area (LMA). Triploid plants bloomed longer but had smaller flowers than diploid plants. Although the whole planting was infected by aerial phytophthora, diploid, tetraploid, and triploid plants were significantly different in their tolerances: all diploid branches were infected, but only a minor infection occurred on one triploid branch, and the transmission remained slow. Flowers of tetraploid plants failed to produce pollen, whereas flowers of triploid plants produced only nonviable pollen grains and fruits aborted after pollination, which led to infertility of induced triploids.
untreated controls across all durations, including the 0-d duration control not submerged in liquid medium, also induced tetraploids (8%). This spontaneous chromosome doubling may have resulted from endoreduplication taking place either in cells of the
, 1968 ; Wan et al., 1989 ). This kind of chimera has frequently been observed in the process of chromosome doubling ( Chen and Gao, 2007 ; Ning et al., 2009 ; Petersen et al., 2003 ; Roy et al., 2001 ; Thao et al., 2003 ). In plant science, the term
possible homozygosity caused by spontaneous chromosome doubling. The total volume of the PCR mixture was 15 μL with 25 ng of genomic DNA, 0.5 U Taq DNA polymerase (Promega, Madison, WI), 0.2 m m of each dNTP (Sigma-Aldrich), 1× PCR buffer, 2 m m MgCl 2
chromosome doubling was occurring as is commonly observed in pepper and cabbage. Spontaneous diploids were also reported by Keleş et al. (2015) in pepper (over 50%), by Gémesné Juhász et al. (2001) in sweet pepper (29.8%), by Gu et al. (2003) in
and tetraploid SHB may only be possible after chromosome doubling of the sparkleberry genome. In 2004–06, open-pollinated sparkleberry seed were treated with colchicine in an attempt to induce chromosome doubling ( Lyrene, 2011 ; Lyrene and Olmstead
chromosome doubling. Fig. 1. Flow cytometry analysis of DNA of ( A ) Korla fragrant pear and ( B ) Zaomeixiang pear leaves. Fruit development and examination of cell size and number. The fruit growth and development period of Zaomeixiang pear