Somatic embryos of camellia (Camellia japonica L.) were differentiated from single cells of hypocotyl explants placed on Murashige and Skoog medium containing GA3. When these somatic embryos were treated with 0.1% colchicine for 1 week, secondary polyploid embryos formed on the hypocotyl of primary embryos. On MS + GA3 medium, polyploid embryos proliferated in a similar manner during subsequent subcultures. These polyploid embryos developed into plantlets that exhibited autopolyploid morphological characteristics.
both urban and forested landscapes ( Pinchot et al., 2017 ). Most elm species are diploid, with 2 n = 28 ( Santamour and Ware, 1997 ). Polyploids are known in only one elm species, U. americana , with diploid and tetraploid populations known in the
although fewer in number. Although developing polyploids from unreduced gametes can result in limited triploid and possibly tetraploid populations, the direct development of tetraploids from modern elite cultivars would help advance breeding goals more
ornamental characteristics such as larger, longer-lasting flowers, thicker petals, and larger, thicker leaves ( Kehr, 1996 ). In addition, polyploid plants, particularly allopolyploids, can have other advantageous traits such as enhanced vigor, improved pest
; 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
) develop an efficient methodology for in vitro shoot regeneration from leaves of R . ‘Fragrantissimum Improved’; and 2) develop an oryzalin-mediated protocol for polyploid induction in ‘Fragrantissimum Improved’. Materials and Methods Plant
The breeding behavior of polyploid Dendrobium orchids (N=19) was investigated by making crosses involving diploids, triploids and tetraploids. Seedlings were obtained from various combinations, although the percentages of viable seed was low for crosses involving triploids. 2N × 2N crosses produced 2N offspring, 4N × 4N crosses produced 4N offspring and 2N × 4N and 4N × 2N crosses produced 3N offspring. 2N × 3N and 3N × 2N crosses gave rise to predominantly 4N progenies and small percentages of aneuploids between the 2N and 3N levels. The increase in ploidy can be attributed to the functioning of unreduced 3N gametes from the 3N parent and the normally reduced N gametes from the 2N parent. 3N × 4N and 4N × 3N crosses produced variable progenies of 5N and aneuploid offspring between the 3N and 4N levels.
( Sharma et al., 2005 ). Polyploid manipulation, particularly triploid production, has been proposed as a genetic approach to develop sterile, noninvasive lantana cultivars ( Czarnecki et al., 2008 ). Similar genetic approaches (polyploid production and
and Whitton, 2000 ). The manipulation of ploidy can also be a valuable tool for plant breeding programs. Polyploids often generate variants that may contain useful characteristics and provide a wider germplasm base for breeding studies ( Ramanna and
( Dirr, 2009 ; McKay, 2001 ). Aronia flowers are thought to be protogynous and self-compatible ( Connolly, 2014 ). Polyploid Aronia species have been reported to reproduce apomictically, via gametophytic apomixis, resulting in embryos that are