Isozyme markers were used to identify cultivars and assess the genetic diversity within a germplasm collection of 49 Hatiora Britt. & Rose clones. The collection included accessions of Easter cactus [H. gaertneri (Regel) Barthlott, H. graeseri Barthlott ex D. Hunt, and H. rosea (Lagerheim) Barthlott] plus H. herminiae (Campos-Porto & Castellanos) Backeberg ex Barthlott and H. salcornioides (Haworth) Britton & Rose. Seven enzyme systems were analyzed: aspartate aminotransferase, glucose-6-phosphate isomerase, leucine aminopeptidase, malate dehydrogenase, phosphoglucomutase, shikimate dehydrogenase, and triosephosphate isomerase. Thirteen loci and 42 alleles were identified. Twenty-one clones (43%) displayed unique isozyme profiles, but the remaining 28 clones shared isozyme profiles with one to three other clones. Percent polymorphic loci, mean number of alleles per locus, and mean heterozygosity were 69, 3.23, and 0.30, respectively, for the entire collection. Isozymes also proved useful for verifying that some progeny were genuine F1 hybrids.
Maureen C. O'Leary and Thomas H. Boyle
G. Préstamo and P. Manzano
The various isozymes of peroxidase of a range of vegetables and kiwifruit were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by specific activity staining. Peroxidase isozymes were determined in potato (Solanum tuberosum L.), carrot (Daucus carota L.), tomato (Lycopersicon esculentum Mill.), kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson], cauliflower [Brassica oleracea (Botrytis group)], green beans (Phaseolus vulgaris L.), and horseradish (Armoracia rusticana Gaertn, Mey Scherb.). There was only one isozyme in cauliflower (70 kDa), two in kiwifruit (45-43 kDa), and a range of isozymes (120-36 kDa) in horseradish. Ascorbic acid inhibited peroxidase activity in the extracts.
Maureen C. O'Leary and Thomas H. Boyle
A germplasm collection of 59 Schlumbergera Lemaire clones was assayed for isozymes of aspartate aminotransferase, glucose-6-phosphate isomerase, leucine aminopeptidase, malate dehydrogenase, phosphoglucomutase, shikimate dehydrogenase, and triosephosphate isomerase. The collection included cultivars of holiday cactus [S. truncata (Haworth) Moran and S. ×buckleyi (T. Moore) Tjaden] plus accessions of S. kautskyi (Horobin & McMillan) N.P. Taylor, S. opuntioides (Löfgren & Dusén) D. Hunt, S. orssichiana Barthlott & McMillan, S. russelliana (Hooker) Britton & Rose, S. ×exotica Barthlott & Rauh, and S. ×reginae McMillan & Orssich. Twelve loci with 36 alleles were detected. Percent polymorphic loci, mean number of alleles per locus, and mean heterozygosity were 83, 3.00, and 0.24, respectively, for the entire collection. Forty-one clones (69%) could be distinguished solely on the basis of their isozyme profiles, but the remaining 18 clones shared profiles with one or two other clones. Isozymes proved useful for determining the parentage of some clones and verifying that some progeny were interspecific hybrids. About 28% of the genetic diversity within the entire collection is unique to four Schlumbergera species that have scarcely been exploited for breeding holiday cactus cultivars.
Randall P. Niedz, Michael G. Bausher, and C. Jack Hearn
leaf and seed glycoproteins were detected after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and electroblotting onto polyvinylidene difluoride (PVDF) membrane when probed with biotinylated lectin at 1 μg·ml-1. Four lectins representing three carbohydrate-binding groups were used as probes. A preformed avidin-biotin-complex (ABC) was used to detect the glycoprotein-bound lectins and resulted in dark bands and little background staining. Concanavalin A (ConA) and wheat germ agglutinin (WGA) resulted in the darkest-staining bands. The four Citrus spp. and one related species studied had unique seed glycoprotein profiles when probed with ConA and WGA. This procedure might be useful in clarifying citrus taxonomy, providing genetic markers, and in physiological studies involving glycoproteins.
G.B. Cap, P.A. Roberts, I.J. Thomason, and T. Murashige
Genotypes of Lycopersicon peruvianum (L.) Mill. and L. peruvianum var. glandulosum (Rick), selected from accessions that possess resistance to Meloidogyne incognita [(Kofoid and White) Chitwood] at high soil temperature (30C), were used as male parents in crosses with L. esculentum (Mill.) susceptible cultivars UC82, Lukullus, Tropic, and male-sterile line ms-31, respectively. The incongruity barrier between the two plant species was overcome by embryo callus and embryo cloning techniques. Hybridity of the F, progeny obtained from each cross was confirmed by differences in leaf and flower morphology, plant growth habits, and by acid phosphatase isozyme phenotypes using polyacrylamide gel electrophoresis. In greenhouse inoculation experiments, F1 plants were highly resistant to M. incognita in soil at 25 and 30C. These results confirmed the successful transfer and expression of heat-stable resistance to M. incognita from L. peruvianum to hybrids with L. esculentum as a preliminary step to introgressing additional root-knot nematode resistance into tomato.
Kee-Yoeup Paek and Eun-Joo Hahn
Adventitious buds regenerated from homogenized leaf tissue of Saintpaulia ionantha Wendl. `Crimson Frost' were micropropagated to determine types and frequencies of the variants obtained. Plants grown for one year in a greenhouse showed 67% variation and 33% normality. A higher rate of variation was observed in leaf color rather than in leaf shape. The variations in leaf color and leaf shape were 67% and 19%, respectively. In regard to flower type, greater numbers of semidouble and double types were obtained as compared to single types. Both flower types showed a much higher rate of normal (mixed) color (81%) as compared to pink, red or white (19%). An sodium dodecylsulfate polyacrylamide gel electrophoresis profile of protein extracted from leaves of the stock plants and the variants indicated no difference between them and did not reflect the variation in phenotype.
Maureen C. O'Leary and Thomas H. Boyle
Cultivars and seedlings of Rhipsalidopsis and Schlumbergera were subjected to isozyme analysis using seven enzyme systems [aspartate aminotransferase (AAT), aminopeptidase (AMP), glucose-6-phosphate isomerase (GPI), malate dehydrogenase (MDH), phosphoglucomutase (PGM), shikimate dehydrogenase (SKD), and triose phosphate isomerase (TPI)]. Isozymes were extracted from phylloclades and roots, and were separated by polyacrylamide gel electrophoresis (PAGE) using single percentage (5% to 10%) gels. Six enzymes exhibited polymorphism in Rhipsalidopsis, whereas all seven enzymes were polymorphic in Schlumbergera. Inheritance studies were performed on AAT, GPI, MDH, PGM, and TPI for Rhipsalidopsis and on AMP, PGM, and SKD for Schlumbergera. Significant segregation distortion was observed in some families. Polymorphic isozymes are potentially useful markers for cultivar identification and for genetic and breeding studies.
Virginia D. Lerch and Timothy Ng
Since the introduction of New Guinea impatiens in 1980 the genus Impatiens has remained the number one selling bedding plant in the U.S. However, basic information concerning the genus is lacking. This study was undertaken to estimate genetic and phenotypic diversity within species and groups of an Impatiens germplasm collection representing seven countries. It includes plants from the 1970 plant expedition co-sponsored by USDA-ARS and the Longwood Foundation (Kennett Square, PA); donations from the Royal Botanic Gardens (Kew, England); and ovule cultured interspecific hybrids created by Dr. Toru Arisumi (USDA, Beltsville, MD). The collection was grown in a common environment and characterized for 31 qualitative and quantitative morphological traits, and electrophoretically characterized for several enzymes using polyacrylamide gel electrophoresis. Evidence concerning putative interspecific hybrids and relationships among Impatiens groups based on morphological and electrophoretic characterization and diversity indices will be presented. Isozyme patterns lending support to hypotheses of center of origin, migration and evolution of Impatiens will also be discussed.
A.R. Dixon, R.B. Boone, A. Gardea, L.S. Daley, and T.L. Righetti
A microcomputer-based image processing system was used to simplify the large number of visual comparisons required to identify various Corylus spp., cultivars, and clonal accessions using polyacrylamide gel electrophoresis isozyme patterns. Photographs of gels stained for peroxidase, acid phosphatase, and phenol oxidase were digitally captured and selected lanes were enhanced and scanned. The scan data were analyzed to locate bands and normalize their position to that of standards. Such data were plotted and a computer-generated isozyme pattern was displayed. Compressed image data were then stored in a database for subsequent automated isozyme pattern comparisons. Photographic records that were previously used in published reports were reevaluated with the computerized system. Species, cultivars, or clones that were characterized in visual evaluations were similarly characterized using the computer method. Computer evaluations usually identified more bands. Band positions were only rarely different and probably resulted from better normalization relative to standard bands when using the computerized procedure.
Charles Lee Biles, Marisa M. Wall, and Kevin Blackstone
Abbreviations: DAF, days after flowering; C 2 H 5 , ethylene; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; DNS. dinitrosalicylic acid. 1 Dept. of Agronomy and Horticulture, New Mexico State Univ., Las Cruces, NM 88003. This