Search Results

You are looking at 1 - 10 of 74 items for :

  • "allotetraploid" x
Clear All
Free access

Ryan N. Contreras, Thomas G. Ranney and Shyamalrau P. Tallury

and was not simply the result of parental chromosome differences. In cases in which sterility is incited by improper chromosome pairing, doubling the chromosome complement (polyploidization) of sterile hybrids to produce allotetraploids provides a

Free access

Jude W. Grosser, Hyun Joo An, Milica Calovic, Dong H. Lee, Chunxian Chen, Monica Vasconcellos and Frederick G. Gmitter Jr

Somatic hybridization in citrus using the embryogenic suspension protoplast plus leaf protoplast fusion model can be considered a reliable technique, because hundreds of allotetraploid somatic hybrids have been produced for both scion and

Free access

Ryan N. Contreras and Thomas G. Ranney

Wide hybridization can potentially lead to the combination of diverse traits, but these hybrids are often sterile as is the case with the inter-subgeneric hybrid Rhododendron `Fragrant Affinity'. Induction of polyploidy can restore chromosome homology and fertility in wide hybrids. In this study we successfully developed an allopolyploid form of R. `Fragrant Affinity' using oryzalin as a mitotic inhibitor and chromosome doubling agent. Approximate genome size (2C), determined using flow cytometry, was 1.6 pg for the diploid and 3.2 pg for the allotetraploid. Pollen viability, determined by staining and germination tests, was 4% and 0%, respectively for the diploid and 68% and 45%, respectively for the allotetraploid. No seeds were produced when the diploid R. `Fragrant Affinity' was crossed with pollen from viable diploid and tetraploid parents. The allotetraploid produced viable seeds and seedlings when crossed with viable pollen from either diploid or tetraploid parents, including self pollination, demonstrating restored fertility. Additional crosses were successfully completed using the allotetraploid as part of an ongoing breeding program to develop new fragrant, cold hardy, evergreen rhododendron.

Free access

Marie Pairon, Anne-Laure Jacquemart and Daniel Potter

for the population analysis of allotetraploid microsatellite data Mol. Ecol. Notes 6 586 589 Marquis, D. 1990 Prunus serotina Ehrh. Black cherry 594 602 Silvics of North America Vol. 2 Hardwoods. U.S. Dept

Free access

Kelly M. Oates, Thomas G. Ranney and Darren H. Touchell

morphology of Rudbeckia will better enable the development of improved varieties. The objectives of this study were to evaluate fertility, morphology, phenology of flowering, and perennialness for lines of diploid and induced allotetraploids of R

Free access

Zenaida Viloria and Jude W. Grosser

Interploid hybridization was conducted using `Key' lime [Citrus aurantifolia (Cristm.) Swing.], `Lakeland' limequat hybrid [C. aurantifolia × Fortunella japonica (Thumb.) Swing.], Palestine sweet lime (C. limettioides Tan.), `Etrog' citron (C. medica L.), and seven lemon [C. limon (L.) Burm. F.] varieties as female progenitors and five allotetraploid somatic hybrids {`Hamlin' sweet orange [C. sinensis (L.) Osbeck] × `Femminello' lemon (C. limon)]; `Key' lime × `Valencia' sweet orange (C. sinensis); `Valencia' sweet orange × rough lemon (C. jambhiri Lush); Milam lemon (purported C. jambhiri hybrid) × `Femminello' lemon (C. limon); and `Valencia' sweet orange × `Femminello' lemon} and two autotetraploids [`Giant Key' lime (C. aurantifolia) and `Femminello' lemon] as pollen progenitors. A few tetraploid × diploid crosses were also performed. Thirty-five parental cross combinations were accomplished in 2000, 2001, and 2002. The breeding targets were seedlessness, cold-tolerance, and disease resistance. Triploid hybrids were recovered through embryo culture. Generation of triploid citrus hybrids was affected by several factors including sexual compatibility, cross direction, embryo developmental stage, pollen viability, as well as horticultural practices and climatic conditions. Efficiency of triploid hybrid production was higher in diploid × tetraploid crosses than the reciprocal. Many more triploid hybrids were generated from lemon seed progenitors compared to the other acid citrus fruit progenitors. `Todo el Año', `Lisbon', and `Limonero Fino 49' showed the highest sexual compatibility. Embryo germination rate and normal plant recovery were also higher in lemons as compared to the other seed progenitors. Low winter temperatures might have affected the hybrid production efficiency from tropical acid fruit progenitors. A total of 650 hybrids (mostly triploid) were transferred to soil. The novel genetic combinations of these progenies should be valuable for the genetic improvement of acid citrus fruit (lemons and limes).

Free access

Timothy F. Wenslaff and Paul M. Lyrene

A study was done to test whether inheritance is tetrasomic or disomic in tetraploid Fl hybrids between 2x Vaccinium elliottii Chapm. and 4x V. corymbosum L. Seventeen Fl hybrids derived from V. elliottii homozygous for recessive anthocyanin deficiency (AD) were confirmed by isozyme analysis and, where V. elliottii was the seed parent, by the presence of anthocyanin. Fertile hybrids with high pollen stainability were assumed to be 4x and duplex for the AD allele, having arisen from 2n gametes in V. elliottii. In nine Fl × Fl crosses, all progeny populations segregated for AD phenotype at or above the expected tetrasomic ratio of 1 AD:35 normal; no AD would be expected with disomic inheritance. Tetraploid AD progeny were used in testcrosses on sixteen Fl hybrids in 1991. Progeny segregated tetrasomically, 1 AD:5 normal. Isozyme loci PGD-2 and PGI-2 also segregated tetrasomically.

Free access

Marie C. Pairon and Anne-L. Jacquemart

Tetraploid black cherry (Prunus serotina) is the only Prunus L. species that has commercial importance as a timber tree in North America and is well known in Europe for its invasive behavior. Inheritance studies have never been performed and it is not known whether the species is allo or autotetraploid. Six microsatellite nuclear markers were used to test the inheritance in progenies of controlled crosses. Inheritance was proven to be disomic at all loci and a typical diploid mendelian inheritance was found at two loci. A first screening of a population in the invasive range showed high number of alleles per locus (ranging from 6 to 16) and high level of observed heterozygosity (0.75 to 1). Knowing that inheritance is disomic at six microsatellite loci and that at least two of them can be treated as codominant, diploid markers will be beneficial for future genetic studies.

Free access

Richard T. Olsen, Thomas G. Ranney and Zenaida Viloria

×Chitalpa tashkentensis Elias & Wisura is a sterile intergeneric hybrid [Catalpa bignonioides Walt. × Chilopsis linearis (Cav.) Sweet]. To restore fertility in ×Chitalpa the following were evaluated: 1) oryzalin as a polyploidization agent, 2) fertility of induced polyploids, and 3) in vitro culture methods for embryo rescue of interploid crosses. Meristems of ×Chitalpa `Pink Dawn' were submerged in an aqueous solution of 150 μm oryzalin for 0, 6, 12, or 24 hours and ploidy analyzed via flow cytometry. As treatment duration increased, recovery of diploids decreased as mixoploids and shoot mortality increased. Two tetraploid shoots occurred in the 24-hour treatment. Four tetraploids and two cytochimeras were stabilized in total. Tetraploids flowered sparsely; however, cytochimeras flowered profusely and these were used to study fertility at the tetraploid level. Diploid ×Chitalpa `Pink Dawn' pollen was essentially nonviable, but cytochimera pollen stained and germinated equal to or greater than pollen of C. bignonioides and C. linearis `Bubba'. Cytochimera ×Chitalpa were selfed yielding tetraploid seedlings, crossed with C. bignonioides to yield triploids, but failed in reciprocal crosses with C. linearis `Bubba' and `Burgundy Lace'. To increase recovery of triploids, germination of triploid and tetraploid embryos was investigated, as either intact ovules or excised embryos, on Schenk and Hildebrandt (SH) basal salts supplemented with sucrose at 20, 40, and 80 g·L-1, presence or absence of 2% coconut-water, and gibberellic acid (GA3) at 0, 1, 2, or 4 μm, and harvested weekly beginning 2 weeks after pollination (WAP). Germination of triploids (cytochimera ×Chitalpa × diploid C. bignonioides) and tetraploids (selfed cytochimera ×Chitalpa) were greatest with excised embryos at 7 WAP on SH supplemented with sucrose at 20 g·L-1 and ≥1 μm GA3. Germination of triploids (diploid C. linearis × cytochimera ×Chitalpa) was <5% at 4, 5, or 6 WAP on the same medium as above. Oryzalin effectively induced polyploidy and restored fertility in ×Chitalpa `Pink Dawn'. Successful crosses between hybrid and parental taxa of different ploidy levels, coupled with embryo culture will facilitate a ×Chitalpa breeding program. Chemical names used: 4(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin).

Free access

Karen R. Harris-Shultz, Brian M. Schwartz, Wayne W. Hanna and Jeff A. Brady

markers except for individual B17-26 for EST-SSR marker ES293862. This information suggests that tetraploid C. dactylon var. dactylon genotypes (i.e., T89) may be a segmental allotetraploid or allopolyploid rather than an autotetraploid ( Bethel et al