Search Results
Genetic relationships among 42 grape accession of at least 15 species were estimated and compared using RAPD and isozyme techniques. These accessions were either hybrids or wild collections of the Asiatic species, the American species, the European grape (V. vinifera), and muscadine grape (V. rotundifolia). A total of 196 RAPD fragments were generated from twenty 10-mer primers. The pairwise similarities among the accession ranged from 0.46 to 0.94. A dendrogram was generated based on the RAPD similarity coefficients. Species/accessions were basically grouped together in accordance with their geographic origins. The similarities and dendrogram resulted from the RAPD analysis were consistent with the ones generated from the isozyme data, and also consistent with the known taxonomic information. This result suggest that the RAPD method, like isozyme, is an useful tool for studying grape genetic relationship/diversity and origination.
Flowering time, growth, and opium gum yield from five seed sources (T, L, B1, B2, B3) of opium poppy (Papaver somniferum L.) collected from different latitudes in three Southeast Asian countries were determined. Plants were grown in six growth chambers at a 11-, 12-, 13-, 14-, 15-, or 16-hour photoperiod with a 12-hour, 25/20 °C thermoperiod. Flower initiation was observed under a dissecting microscope (40×) to determine if time to floral initiation was identical for all accessions across a wide range of photoperiods. The main capsule was lanced for opium gum at 10, 13, and 16 days after flowering (DAF). Plants were harvested at 21 DAF for plant height, leaf area, and organ dry-weight determinations. In a 16-hour photoperiod, flower initiation was observed 10 days after emergence (DAE) for B1 vs. 8 DAE for the other four accessions. Flowering time was affected most by photoperiod in B1 and least in B2. Flowering times for B3, L, and T were similar across the range of photoperiods. B2, B3, and L had the highest gum yields per capsule; even though B1 had the greatest total plant biomass, it produced the lowest gum yield. There was no difference among accessions in the average ratio of gum: individual capsule volume. For the ratio of gum: capsule dry weight, only the difference between T and B1 was significant. Capsule size did affect these ratios slightly. T had a larger gum: volume ratio for larger capsules, and B3 had a smaller gum: dry-weight ratio for heavier capsules. Flowering time varied up to 40%, capsule dry weight up to 41%, and opium gum yield up to 71% for the five accessions across all treatments. No relationship was found between flowering time and the latitude where the seed sources were collected. Time to flower initiation could not be used to predict time to anthesis because floral development rates varied significantly among accessions and photoperiods. Capsule volume and dry weight were useful in estimating gum yield.
The grape is an important horticultural crop that is grown worldwide. Breeding a new grape cultivar by conventional means normally will take several generations of backcross, at least 15 years. The efficiency and speed of selection can be accelerated if genetic markers are available for early screening. This project is designed to generate RAPD markers linked to viticulturally important traits, including seedlessness and pistillate genes. A F1 population with 64 progenies of V. vinifera was used for the RAPD analysis. Bulked Segregant Analysis (BSA) method was used for RAPD primer screening. Three-hundred primers were screened between the two pairs of pooled DNA samples, seeded and seedlessness, pistillate and perfect flowers. At least 10 primers produced one polymorphism each between the pools. Further analysis revealed that one of these RAPDs cosegregated tightly with the seedlessness trait, while the others either had loose linkage or no linkage to the traits. To make the RAPD marker useful for breeding selection, an attempt was made to convert it into SCAR marker. The results demonstrated that the RAPD marker may be useful for grape breeding and interpreting inheritance of a particular trait in grapes.
Plantlets were regenerated from in vitro-grown leaf explants of five genotypes of Liquidambar formosana on WPM basal medium supplemented with different concentrations of TDZ and NAA. With the addition of 0.27 μm NAA, regeneration efficiency was increased by 2- to 4-fold over that with TDZ alone. Lower concentrations of TDZ (0.45–2.27 μm) were beneficial for regenerating shoot clusters. Four genotypes (P2, P6, P9, and P11) showed high regeneration rates (up to 90%), whereas genotype P13 showed a low capability for shoot regeneration on all media tested (<35%). For all five genotypes, the optimum medium for inducing adventitious shoots was WPM supplemented with 1.14 μm TDZ and 0.27 μm NAA, on which regeneration rate ranged from 72.6% to 89.5% and adventitious shoot clusters per regenerating leaf explant ranged from 2.63 to 3.11 in four genotypes (P2, P6, P9, and P11), while for P13, the regeneration rate and number of shoot clusters per regenerating explant were 23% and 1.39, respectively. Transfer of shoot clusters to WPM basal medium containing 0.54 μm NAA, 2.22 μm BA, and 1.44 μm GA3, resulted in shoot elongation. All the elongated shoots were rooted on WPM supplemented with 9.84 μm IBA, and plantlets were transplanted to soil successfully.
Chemical names used: 6-benzyladenine (BA), gibberellic acid (GA3), indole-3-butyric acid (IBA), 1-naphthalene acetic acid (NAA), plant growth regulator (PGR), thidiazuron (TDZ), woody plant medium (WPM).
Abstract
The objective of our research is to understand the genetic basis of embryogenesis. Somatic embryogenesis from carrot culture was chosen as the experimental system because of its simplicity and the ease with which it lends itself to obtaining a large number of embryos for genetic and biochemical experiments. Our general philosophy is to avoid media manipulation and to focus on gene expression during embryogenesis. One approach is to isolate genes preferentially expressed at specific stages of embryogenesis, and then to study the role of these genes in development.