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Charles A. Walker Jr. and Dennis J. Werner

Two banding patterns were revealed by phosphoglucomutase (PGM) isozyme analysis of 24 accessions of Cherokee rose (Rosa laevigata Michx.) from eight southeastern states, based on the presence (in 5 accessions) or absence (in 19 accessions) of an additional slow-migrating band. RAPD analysis of these accessions showed a corresponding division into the same two groups determined by PGM analysis, except for two accessions with unique RAPD phenotypes. Field-grown accessions showed distinguishing morphological characters corresponding to the groupings from the isozyme and RAPD analyses. Those in the predominant isozyme and RAPD groups, as well as the two with unique RAPD phenotypes, exhibited smooth lateral stems, while those in both nonpredominant groups exhibited markedly bristly laterals. These results suggest that the 24 accessions are ramets of two major clones with one clone predominating and that, contrary to long-standing belief, the Cherokee rose has not naturalized by reseeding in the southeast. PGM and RAPD analyses of putative Cherokee rose hybrids `Anemone' and `Silver Moon' showed that `Anemone' is likely to be such a hybrid but that `Silver Moon' is not. Historical records revealed that widespread vegetative propagation of the Cherokee rose was initiated in 1820-21 and that L. Wiesener, not J.C. Schmidt, was the originator of `Anemone'.

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Michael A. Creller and Dennis J. Werner

Scanning electron microscopy (SEM) was used to compare the novel surface morphology of `Marina' peach [plant introduction (PI) 133984] to a normal peach (`Contender') and a nectarine (`Sunglo'). Samples were collected before, during, and after anthesis. Compared to `Contender', `Marina' showed different trichome structure, lower trichome density, and delayed initiation of trichomes on the gynoecium. No pubescence was observed on `Sunglo' nectarine at any sampling date. Trichomes were present on the flower bud scales of all three cultivars. Arrangement and structure of trichomes on flower bud scales of `Marina' differed from those on `Contender' and `Sunglo'.

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Dennis J. Werner and Michael A. Creller

Inheritance of the sweet kernel trait was studied in F1 and F2 families generated by crossing `Summer Beaut' nectarine (sweet kernel) with `Ellerbe' and `Biscoe' peach. F1 plants showed bitter kernel. Segregation in the F2 fit a 3 bitter : 1 sweet phenotypic ratio, suggesting that sweet kernel is controlled by a single recessive gene, for which the symbol sk is proposed. Sweet kernel (sk) was linked to nectarine (g) at a map distance of 12 cM. Seed bitterness phenotype is controlled by the genotype of the maternal tree and not the genotype of the individual embryo. Inheritance of male sterility derived from plant introduction (PI) 240928 and allelism of male sterile genes found in `Chinese Cling' and `White Glory' were investigated. Analysis of F1, F1 open-pollinated, and BC1 families derived from crossing PI 240928 with six different wild-type cultivars showed that male sterility in PI 240928 is controlled by cytoplasmic factors. Allelism studies showed that the male-sterile gene found in `White Glory' is not allelic to ps found in `Chinese Cling', and hence is designated ps2.

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Dennis J. Werner and Michael A. Creller

Inheritance of male sterility in peach [Prunus persica (L.) Batsch] Plant Introduction (PI) 240928 was investigated. Crosses of PI 240928 with five wild-type clones yielded all male-sterile offspring, indicating dominant gene action. Inheritance of the sweet kernel trait in peach was studied in F1 and F2 progeny of `Summer Beaut' nectarine (sweet kernel) × `Biscoe' peach (bitter kernel). All four F1 progeny were bitter. Segregation in an F2 of 80 progeny fit a ratio of 3 bitter: 1 sweet. We propose that the gene controlling the sweet kernel trait be designated sk. Sweet kernel (sk) was linked to nectarine (g) at a map distance of 17 cM. Evaluation of the peach PI collection showed that PI 129678 (`Stanwick' nectarine) and PI 34685 (`Quetta' nectarine) were the only clones with a sweet kernel. Crosses between `Davie II' and `Honeyglo' nectarine (dwdw) confirmed that the gene conferring the dwarf phenotype in progeny of `Davie II' is non-allelic to dw.

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Dennis J. Werner and Layne K. Snelling

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Dennis J. Werner and Layne K. Snelling

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Dennis J. Werner and Layne K. Snelling

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Jessica G. Barb, Dennis J. Werner and Robert J. Griesbach

Stokes aster [Stokesia laevis (J. Hill) Greene] is a herbaceous perennial endemic to the coastal plains of the southeastern United States. Anthocyanin and copigment aglycones from flowers were characterized using high-performance liquid chromatography. Blue, lavender, violet, and albescent flowers each contained the anthocyanidin petunidin, although albescent flowers contained a substantially smaller amount. Pale pink flowers were found to contain only cyanidin. Anthocyanins and carotenoids were not present in pale yellow flowers of this species. All flowers contained the flavone luteolin. Genetic analysis of F1, F2, and BC1 populations suggested that flower color in stokes aster is controlled by at least three loci. F2 populations of blue × albescent and blue × pale yellow flowering plants segregated in a 3:1 ratio of blue to albescent or pale yellow flowered progeny, indicating that albescent and pale yellow flower colors were recessive and each controlled by a single locus with two alleles. BC1 populations supported these results. We propose the symbols A and Y: AA and YY plants synthesize a normal amount of anthocyanins, aa plants synthesize a reduced amount of anthocyanins, and yy plants do not synthesize anthocyanins. When the two mutant phenotypes (i.e., albescent [aa] and pale yellow [yy]) were crossed, the F1s were blue, and the F2 segregated in a 9 blue:3 albescent:4 yellow ratio, indicating that the recessive locus (y), when homozygous, was epistatic to other loci involved in anthocyanin production (e.g., A), and that the genotypes of the parents used in these crosses were aaYY (albescent) and AAyy (pale yellow). F1, F2, and BC1 populations of blue (petunidin) × pale pink (cyanidin) flowering plants revealed that cyanidin production was recessive and controlled by a single locus, P, with two alleles, whereby PP plants synthesize petunidin and pp plants synthesize cyanidin. It was difficult to distinguish albescent- and pale pink-flowered progeny in segregating generations, therefore three genetic models were proposed and tested to determine the genotype(s) (i.e., AApp, Aapp, or aapp) of the pale pink-flowered plants. Based on these analyses, we propose a theoretical biochemical pathway for flavonoid biosynthesis in stokes aster.

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Richard T. Olsen, Thomas G. Ranney and Dennis J. Werner

Inheritance of two mutant foliage types, variegated and purple, was investigated for diploid, triploid, and tetraploid tutsan (Hypericum androsaemum). The fertility of progeny was evaluated by pollen viability tests and reciprocal crosses with diploids, triploids, and tetraploids and germinative capacity of seeds from successful crosses. Segregation ratios were determined for diploid crosses in reciprocal di-hybrid F1, F2, BCP1, and BCP2 families and selfed F2s with the parental phenotypes. F2 tetraploids were derived from induced autotetraploid F1s. Triploid segregation ratios were determined for crosses between tetraploid F2s and diploid F1s. Diploid di-hybrid crosses fit the expected 9: 3: 3: 1 ratio for a single, simple recessive gene for both traits, with no evidence of linkage. A novel phenotype representing a combination of parental phenotypes was recovered. Data from backcrosses and selfing support the recessive model. Both traits behaved as expected at the triploid level; however, at the tetraploid level the number of variegated progeny increased, with segregation ratios falling between random chromosome and random chromatid assortment models. We propose the gene symbol var (variegated) and pl (purple leaf) for the variegated and purple genes, respectively. Triploid pollen stained moderately well (41%), but pollen germination was low (6%). Triploid plants were highly infertile, demonstrating extremely low male fertility and no measurable female fertility (no viable seed production). The present research demonstrates the feasibility of breeding simultaneously for ornamental traits and non-invasiveness.

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Jose X. Chaparro, Ronald R. Sederoff and Dennis J. Werner

Total cellular DNA has been extracted from leaves and\or seed of Prunus dulcis, P. persica, P. mira, P. davidiana, P. persica subsp. ferganensis, and P. triloba. Chloroplast restriction fragments have been visualized by Southern blot analysis using heterologous probes from a petunia chloroplast library. Analysis of preliminary data separates the species into three groups. The first contains P. dulcis, P. mira, and P. davidiana; the second P. kansuensis, P. persica, and P. persica subsp. ferganensis; and the third P. triloba.

PCR amplification using oligos for cytosolic glyceraldehyde-3-phosphate dehydrogenase yields genomic fragments approximately 1kb in size from P. dulcis and P. triloba. Sequence analysis will be performed to determine species relationships at the gene level.