Crossability, Cytogenetics, and Reproductive Pathways in Rudbeckia Subgenus Rudbeckia

Palmer, Irene E.; Ranney, Thomas G.; Lynch, Nathan P.; Bir, Richard E.

doi:10.21273/hortsci.44.1.44

Cited by 16 publications

(24 citation statements)

References 6 publications

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“…Seedlings with genomes sizes surpassing their parents have been reported for diploid-triploid crosses in other woody plants including Pyrus (Phillips et al, 2016), Ulmus (Santamour, 1971), andPopulus (Harder et al, 1976;Wang et al, 2010). Similar results have been found in herbaceous taxa including Miscanthus sinensis (Rounsaville et al, 2011) Rudbeckia (Palmer et al, 2009), Lilium (Lim et al, 2003;Marasek-Ciolakowska et al, 2014), Musa (Osuji et al, 1997), and Cucumis sativus (Diao et al, 2009). Most studies proposed sexual polyploidization via the union of unreduced gametes from one or both parents as the likely cause of the large seedling genomes.…”

Section: Series Zsupporting

confidence: 54%

“…Previous studies have produced models based on a holoploid genome size of a theoretical average, single chromosome based on parent genome sizes, and chromosome counts. Although some estimates of aneuploid chromosomes have been based solely on hypothetical chromosome size (Palmer et al, 2009), several studies have tested this model with root squashes and found most of their predictions to be concurrent with the true chromosome number or accurate within two to three chromosomes in Primula (Hayashi et al, 2009), Lilium (Lim et al, 2003), and Calluna (Behrend et al, 2015). Considering these previous studies and the relatively uniform chromosome size observed in lilac (Fig.…”

Section: Series Zmentioning

confidence: 99%

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Ploidy and Genome Size in Lilac Species, Cultivars, and Interploid Hybrids

Lattier¹,

Contreras²

2017

J. Amer. Soc. Hort. Sci.

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Genome size variation can be used to investigate biodiversity, genome evolution, and taxonomic relationships among related taxa. Plant breeders use genome size variation to identify parents useful for breeding sterile or improved ornamentals. Lilacs (Syringa) are deciduous trees and shrubs valued for their fragrant spring and summer flowers. The genus is divided into six series: Syringa (Vulgares), Pinnatifoliae, Ligustrae, Ligustrina, Pubescentes, and Villosae. Reports conflict on genome evolution, base chromosome number, and polyploidy in lilac. The purpose of this study was to investigate genome size and ploidy variation across a diverse collection. Flow cytometry was used to estimate monoploid (1Cx) and holoploid (2C) genome sizes in series, species, cultivars, and seedlings from parents with three ploidy combinations: 2x x 2x, 2x x 3x, and 3x x 2x. Pollen diameter was measured to investigate the frequency of unreduced gametes in diploid and triploid Syringa vulgaris cultivars. Three triploids of S. vulgaris were observed: ‘Aucubaefolia’, ‘Agincourt Beauty’, and ‘President Grévy’. Across taxa, significant variations in 1Cx genome size were discovered. The smallest and largest values were found in the interspecific hybrids S. ×laciniata (1.32 ± 0.04 pg) and S. ×hyacinthiflora ‘Old Glory’ (1.78 ± 0.05), both of which are in series Syringa. Series Syringa (1.68 ± 0.02 pg) had a significantly larger 1Cx genome size than the other series. No significant differences were found within series Pubescentes (1.47 ± 0.01 pg), Villosae (1.55 ± 0.02 pg), Ligustrina (1.49 ± 0.05 pg), and Pinnatifoliae (1.52 ± 0.02 pg). For S. vulgaris crosses, no significant variation in 2C genome size was discovered in 2x x 2x crosses. Interploid crosses between ‘Blue Skies’ (2x) and ‘President Grévy’ (3x) produced an aneuploid population with variable 2C genome sizes ranging from 3.41 ± 0.03 to 4.35 ± 0.03 pg. Only one viable seedling was recovered from a cross combination between ‘President Grévy’ (3x) and ‘Sensation’ (2x). This seedling had a larger 2C genome size (5.65 ± 0.02 pg) than either parent and the largest 2C genome size currently reported in lilac. ‘Sensation’ produced 8.5% unreduced pollen, which we inferred was responsible for the increased genome size. No unreduced pollen was discovered in the other diploids examined. Increased ploidy may provide a mechanism for recovering progeny from incompatible taxa in lilac breeding.

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Section: Series Zsupporting

confidence: 54%

Section: Series Zmentioning

confidence: 99%

Ploidy and Genome Size in Lilac Species, Cultivars, and Interploid Hybrids

Lattier¹,

Contreras²

2017

J. Amer. Soc. Hort. Sci.

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“…In this study, monoploid genome sizes varied up to 23% among species. In Rudbeckia, a hybrid was recovered when there was a difference in genome size of >300% (Palmer et al, 2009). The much smaller range in Cotoneaster suggests variation in monoploid genome size, thus chromosome size, is not expected to hinder interspecific hybridization.…”

Section: Resultsmentioning

confidence: 99%

Ploidy Levels, Relative Genome Sizes, and Base Pair Composition in Cotoneaster

Rothleutner¹,

Friddle²,

Contreras³

2016

J. Amer. Soc. Hort. Sci.

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The genus Cotoneaster (Rosaceae, Maloideae) is highly diverse, containing ≈400 species. Like other maloids, there is a high frequency of naturally occurring polyploids within the genus, with most species being tetraploid or triploid. Apomixis is also prevalent and is associated with polyploidy. The objective of this study was to estimate genome sizes and infer ploidy levels for species that had not previously been investigated as well as compare estimates using two fluorochromes and determine base pair (bp) composition. Chromosome counts of seven species confirmed ploidy levels estimated from flow cytometric analysis of nuclei stained with 4′,6-diamidino-2-phenylindole (DAPI). Monoploid (1Cx) genome sizes ranged from 0.71 to 0.96 pg. Differences in monoploid genome size were not related to current taxonomic treatment, indicating that while chromosome sizes may vary among species, there are no clear differences related to subgeneric groups. A comparison of DAPI and propidium iodide (PI) showed a difference in DNA staining in Cotoneaster comparable to other rosaceous species. Base pair composition (AT%) in Cotoneaster ranged from 58.4% to 60.8%, which led to overestimation of genome size estimates in many cases—assuming the estimates of the DNA intercalator are accurate. Our findings will inform breeders with regard to the reproductive behavior of potential parents and may be used to confirm hybrids from interploid crosses.

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“…The genus Rudbeckia consists of %30 species endemic to North America (Armitage, 1997;Palmer et al, 2009). The genus includes annuals, biennials, and perennial species (Perdue, 1957) and is divided into two subgenera, Rudbeckia subg.…”

mentioning

confidence: 99%

“…The annual species, Rudbeckia hirta, includes diploid (2n = 2x = 38) and tetraploid (2n = 4x = 76) cultivars with a diverse range of flower colors and forms (Palmer et al, 2009). Cultivars of R. hirta range in mature height from 0.5 to 1.0 m with tetraploid cultivars typically having larger flowers and greater height (Hansen and Stahl, 1993;Palmer et al, 2009). However, R. hirta is short-lived and susceptible to certain diseases including cercospora leaf spot (Cercospora sp.)…”

mentioning

confidence: 99%

Influence of Induced Polyploidy on Fertility and Morphology of Rudbeckia Species and Hybrids

Oates¹,

Ranney²,

Touchell³

2012

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Rudbeckia spp. are adaptable and valuable ornamental wildflowers. Development of new varieties of Rudbeckia spp., with improved commercial characteristics, would be highly desirable. Interspecific hybridization and induced polyploidy may be avenues for improvement within the genus. The objective of this study was to evaluate fertility, morphology, phenology of flowering, and perennialness (overwintering survival) for lines of diploid and induced allotetraploids of R. subtomentosa × hirta and diploid and autotetraploids of R. subtomentosa ‘Henry Eilers’. Polyploid lines were developed and propagated in vitro and then grown ex vitro in a randomized complete block design with 12 replications. Compared with their diploid counterparts, autotetraploid lines of R. subtomentosa ‘Henry Eilers’ had similar internode lengths, plant heights, number of stems, flowering times (date at first anthesis), and fall and spring survival (100%); reduced number of inflorescences and male and female fertility; and increased inflorescence diameters. Compared with their diploid counterparts, allotetraploids of R. subtomentosa × hirta had similar internode lengths, reduced number of inflorescences, delayed flowering times, and increased pollen staining. Allotetraploids had limited male and female fertility compared with no detectable fertility in their diploid counterparts. Plant height and number of stems either decreased or showed no change with induced allotetraploidy. Spring survival of diploid hybrid genotypes ranged from 0% to 82% and was not improved in the allotetraploid hybrids. For a given genotype, some polyploidy lines varied significantly in certain morphological traits (e.g., plant height) indicating somaclonal variation may have developed in vitro or there were variable genomic or epigenetic changes associated with induced polyploidy.

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Crossability, Cytogenetics, and Reproductive Pathways in Rudbeckia Subgenus Rudbeckia

Cited by 16 publications

References 6 publications

Ploidy and Genome Size in Lilac Species, Cultivars, and Interploid Hybrids

Ploidy and Genome Size in Lilac Species, Cultivars, and Interploid Hybrids

Ploidy Levels, Relative Genome Sizes, and Base Pair Composition in Cotoneaster

Influence of Induced Polyploidy on Fertility and Morphology of Rudbeckia Species and Hybrids

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