spp. As a result of the large relative genome size of C. eydeana, Magnolia virginiana ‘Jim Wilson’ (Moonglow™) was used as an internal standard (absolute 2C = 3.92 pg) for those analyses following Parris et al. (2010) . Internal standards were
Kimberly Shearer and Thomas G. Ranney
J. Kevin Parris, Thomas G. Ranney, Halina T. Knap, and W. Vance Baird
genome size using DAPI (AT preferential) or propidium iodide (PI) (intercalating) fluorochrome stains and estimate bp composition for representative taxa from 10 taxonomic sections. Materials and Methods Relative genome size and ploidy level determination
Thomas G. Ranney, Tracy H. Thomasson, Kristin Neill, Nathan P. Lynch, and Mark Weathington
ploidy and relative genome size for a diverse collection of species and cultivars of aucuba using flow cytometry and cytology and to make additional observations on the heritability of spotted leaf variegation of specific cultivars. Materials and Methods
Joseph J. Rothleutner, Mara W. Friddle, and Ryan N. Contreras
relative genome sizes and produce ploidy estimates across a wide selection of Cotoneaster including its breadth of taxonomic groups. Materials and Methods Plant material. Germplasm was collected through various means including whole plants from nurseries
Dominic A. Gillooly and Thomas G. Ranney
randomized fashion. Data for 1Cx values were subjected to analysis of variance and means. Different taxa were separated using Tukey’s honestly significant difference, P ≤ 0.05 (SAS version 8.02; SAS Institute, Cary, NC). Table 1. Relative genome sizes and
Darren H. Touchell, Thomas G. Ranney, Dilip R. Panthee, Ronald J. Gehl, and Alexander Krings
. Further, there has been no characterization of wild collected Arundo from South Asia. Thus, the objective of this study was to evaluate genetic diversity, cytogenetics (ploidy, chromosome numbers, and relative genome sizes) and biomass yields of Arundo
Thomas G. Ranney, Connor F. Ryan, Lauren E. Deans, and Nathan P. Lynch
recombination and illegitimate recombination ( Grover and Wendel, 2010 ; Soltis et al., 2015 ). There have only been limited reports on chromosome numbers and relative genome sizes for species and cultivars of Illicium . A base chromosome number of x = 14
Irene E. Palmer, Thomas G. Ranney, Nathan P. Lynch, and Richard E. Bir
Rudbeckia L. are valuable nursery crops that offer broad adaptability and exceptional ornamental merit. However, there is little information on interspecific and interploid crossability and ploidy levels of specific cultivars. The objectives of this study were to determine the ploidy levels and relative DNA contents (genome sizes) of selected species and cultivars, to evaluate self-compatibility and crossability among species and ploidy levels, and to explore reproductive pathways in triploid R. hirta L. with the goal of facilitating future breeding endeavors and development of new hybrids. Reciprocal interspecific crosses were performed between R. hirta cultivars and R. fulgida Ait., R. missouriensis Engelm. ex C.L. Boynton & Beadle, and R. subtomentosa Pursh. as well as reciprocal interploid crosses among four R. hirta cultivars. A combination of relative DNA content analysis and chromosome counts was used to test for hybridity and to determine ploidy levels for selected species, cultivars, and interploid R. hirta F1 hybrids. Of the specific clones tested, R. subtomentosa and R. missouriensis were diploid, R. fuligida varieties were tetraploid, and R. hirta include both diploid and tetraploid cultivars. Mean 1Cx DNA content varied over 320% among species. The interploid R. hirta crosses produced triploids as well as pentaploids and hexaploids. Seedlings from open-pollinated triploid R. hirta appeared, based on diverse phenotypes and DNA contents, to be aneuploids resulting from sexual fertilization, not apomixis. Of the 844 seedlings from interspecific F1 crosses, only one individual, R. subtomentosa ×R. hirta, had a DNA content intermediate between its parents and was confirmed as the only interspecific hybrid. Although most taxa had low self-fertility, seedlings (with genomic sizes similar to their maternal parent) resulted after interspecific crosspollination, indicating that pseudogamy is one reproductive pathway in Rudbeckia species.
David J. Roberts and Dennis J. Werner
Cercis is an ancient member of Fabaceae, often cultivated as an ornamental tree, and can be found in numerous regions around the world. Previous studies have reported Cercis canadensis as being diploid with 2n = 2x = 14. However, there have been no further investigations into ploidy and genome size variation among Cercis taxa. A study was conducted to evaluate the relative genome size and ploidy levels of numerous species, cultivars, and botanical varieties of Cercis, representing taxa found in North America, Asia, and the Middle East. In addition, the genome size of Bauhinia forficata, a close relative of Cercis, was also determined. Genome size estimates (2C values) were determined by calculating the mean fluorescence of stained nuclei via flow cytometry. Propidium iodide was used as the staining agent and Glycine max was used as an internal standard for each taxon analyzed. Genome size estimates for all Cercis sampled ranged from 0.70 to 0.81 pg with an average size of 0.75 pg. The genome size of B. forficata was found to be smaller than any other Bauhinia sp. currently on record, with an average size of 0.87 pg. This study confirmed an initial estimation of the genome size of Cercis chinensis and found that floral buds of Cercis proved to be an excellent source of plant tissue for obtaining intact nuclei. All species, botanical varieties, and cultivars of Cercis surveyed for this study had remarkably similar genome sizes despite their wide range of distribution. This information can facilitate a better understanding of phylogenetic relationships within Cercideae and Cercis specifically.
Whitney D. Phillips, Thomas G. Ranney, Darren H. Touchell, and Thomas A. Eaker
Flowering pears are popular landscape plants due to a combination of desirable traits including broad adaptability, pest resistance, and attractive ornamental features. However, in some areas, flowering pears readily reseed and naturalize. Considering the value and utility of these trees, the development of infertile cultivars would be desirable. Breeding of triploid plants is one of the approaches that has been successfully used to develop seedless cultivars of many crops. The objective of this study was to evaluate female fertility and reproductive pathways of triploid flowering pear hybrids. Female fertility was characterized by evaluating fruit set, seeds per fruit, seed germination, seedlings per flower, and percent relative fertility [(seedlings per flower for triploid/seedlings per flower for diploid control) × 100]. Flow cytometry was used to determine relative genome sizes and ploidy levels of female parents, seedlings, and seeds (both embryo and endosperm) and to make inferences regarding reproductive pathways. Mean holoploid genome sizes were confirmed for the diploid [1.25 ± 0.05 (se) pg] and triploid [1.88 ± 0.12 (se) pg] female parents. Relative female fertility was significantly reduced in triploids, but varied considerably among accessions and ranged from 0.0% to 33.6%. Of the 13 triploids used in this study, five accessions had a relative fertility of <2%. One accession had no measurable female fertility. Cytometric analysis of seeds and seedlings from triploid maternal parents showed that they were predominantly abnormal aneuploids, which typically results in seedlings with reduced fitness and fertility. Fertilization with unreduced gametes, apomixis, and pseudogamy were documented in triploid-derived embryos/offspring, but were relatively uncommon. The considerable reduction in female fertility of some triploid selections, coupled with the limited production of primarily aneuploid progeny, provides desirable options for new infertile flowering pears to prevent or reduce reseeding and naturalizing.