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

Abstract

Tetraploids of daylily have taken a leading position among the daylily cultivars due to desirable traits such as vigorous growth and flowers with more intense colour. In our previous studies, several tetraploids of daylily cultivars 'Blink of an Eye' and 'Berlin Multi' were obtained using in vitro techniques with different antimitotic agents (colchicine, oryzalin, trifluralin, and amiprophos methyl). The purposes of this study were to evaluate changes in daylily tetraploids in relation to their diploid counterparts and to assess variation among diploids and tetraploids derived from genetically homogenous plant material treated with antimitotic agents. In the first year of the ex vitro cultivation, growth of tetraploids was poorer in comparison with diploids, but in the second year, tetraploid growth was much more vigorous. Compared to diploids, in tetraploids of both cultivars percentage of flowering plants was lower, flowering was delayed by 8 days and 1 month in 'Blink of an Eye' and 'Berlin Multi', respectively, and bud number per scape was lower by approximately 20 and 40 %, respectively. Tetraploid leaves and flowers of both cultivars were significantly larger, chlorophyll concentration index was higher by approximately 40 %, and stomata were longer by 35 %. In 'Berlin Multi' tetraploids, inflorescence stems were shorter by 20 %. In 'Blink of an Eye', variation in flower colour tone and shape and stamen malformation rate was detected both within the unconverted diploids and tetraploids but was more evident in tetraploids. In both cultivars, variation was also found in the nuclear DNA content, which ranged in diploids and tetraploids, respectively, 8.02-8.53 and 16.01-17.13 pg in 'Berlin Multi ' and 8.28-8.71 and 15.93-17.36 pg in 'Blink of an Eye'. Since the variation, while less evident, also occurred in the diploids (regenerated from the antimitotic treated material), we suppose that these variations could be due to antimitotic agents that can induce not only chromosome doubling but also chromosomal and gene mutations. The extent and character of these changes can be related to parental genotype and/or antimitotic agent. Further research is required at the cytological and molecular level to explain the character of changes, epigenetic and/or genetic.

Flow cytometry – a modern method for exploring genome size and nuclear DNA synthesis in horticultural and medicinal plant species

“…Polyploids (usually tetraploids) are most often obtained in vitro or ex vitro by treatment with an antimitotic agent, and plants of desirable ploidy are selected using FCM. This approach was successfully performed for 3 Hibiscus species, Rhododendron hybrid R. × kosterianum, Syringa vulgaris × S. pinnatifolia, a few Rosa species, Gerbera jamesonii, Hemerocallis × hybrida, and Petunia axillaris (Rose et al, 2000;Väinölä, 2000;Van Huylenbroeck et al, 2000;Allum et al, 2007;Crespel et al, 2015;Podwyszyńska et al, 2015;Regalado et al, 2017). The induction of artificial polyploidy can also increase the production of important medicinal compounds and for this reason was introduced into Ocimum basilicum, Thymus persicus, and Trachyspermum ammi (Omidbaigi et al, 2010;Tavan et al, 2015;Noori et al, 2017).…”

Nuclear DNA Content and Ploidy Level of Apple Cultivars Including Polish ones in Relation to Some Morphological Traits

“…In turn, 'Jonathan 2-4-4' had significantly thicker lamina and a higher chlorophyll content than diploid ' Jonathan'. These phenotype characteristics of chimeric cultivars indicate their tetraploidy in L2 since tetraploids of apple (Lespinasse and Noiton, 1986;Blanke et al, 1994;Sedysheva and Gorbacheva, 2013) and many other species (Jaskani et al, 2005;Elradi and Unal, 2010;González-Rodríguez and Grajal-Martín, 2013;Podwyszyńska et al, 2015) have larger and thicker leaves and often a higher chlorophyll content. Our supposition corresponds well with the reports on Hemerocallis ploidy chimeras 2-4-4 and 2-4-2 whose stomata were the same size as in diploids but the leaf sizes were as in tetraploids (Arisumi, 1964;Podwyszyńska et al, 2011).…”

“…In general, polyploidy is associated with enhanced nuclear DNA content that translates into larger nuclei, cells and stomata sizes. It is often related to variation in morphological, physiological or phenological characteristics such as, e.g., larger leaves, flowers and fruits or late flowering time (Webster, 1996;Jaskani and Khan, 2000;Ramanna and Jacobsen, 2003;Anssour et al, 2009;Rogalska et al, 2007;Podwyszyńska et al, 2015).…”

Combined Analysis of mRNAs and miRNAs to Identify Genes Related to Biological Characteristics of Autotetraploid Paulownia

“…Ploidy-dependent gene regulation has been studied in plants under abiotic and biotic stresses [38,39]. Previous results revealed that tetraploid Paulownia was superior to its corresponding diploid as it had better timber quality, higher activity of peroxidases and superoxide dismutase, larger stoma size, and higher stress resistance [15,16], and changes in gene expression between diploid and tetraploid Paulownia have been reported [17,28,40,41], but these results were based on de novo transcriptome data, which might not provide sufficient evidence to fully understand ploidy-dependent gene regulation.…”