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Mark A. Hubbard

College of the Ozarks is a private, liberal arts college in southwestern Missouri, and the Agriculture Dept. has recently begun instituting a variety of horticulture courses in an effort to meet the increasing student interest in horticultural science. The objective is to educate and train students in the horticulture fundamentals and specific production areas (advanced courses). Also, the College is in the process of constructing teaching and demonstration gardens to be used in conjunction with classroom instruction. These gardens will include a plant materials collection and horticultural crop production areas. Additionally, as the College requires that students work part-time at any of several work “stations” on campus, students have the opportunity to gain experience in landscaping or in production greenhouses on campus. Currently, the college has 10,000 ft2 of greenhouse space that is operated for the purposes of producing plants for campus landscaping, maintaining a ≥6000 orchid collection, and producing plants for seasonal sales. The college intends to integrate the classroom instruction, experiences in the teaching gardens, and the required work experiences to provide students with a complete horticultural education. Comments and suggestions for this budding endeavor are highly sought after.

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Sriyani Rajapakse, Mark Hubbard, Albert Abbott, Robert Ballard and John Kelly

Restriction Fragment Length Polymorphisms (RFLPs) were investigated in rose cultivars as a means of reliable cultivar identification. A random genomic DNA library was generated by shotgun cloning HindIII digested fragments of DNA extracted from rose cultivar Confection into pUC8 plasmid of Escherichia coli strain JM 83. Compared to genomic clones carrying low or highly repeated sequences, clones with moderately repeated sequences were most effective in cultivar identification. These clones were identified by hybridizing rose DNA fragments from the library with genomic DNA from `Confection'. Clones with moderately repeated copy sequences were used as probes to detect the presence of RFLPs by Southern hybridization of EcoRI digested genomic DNA of various rose cultivars. Several of these probes have revealed RFLPs useful in cultivar identification. By using a combination of two or more of these probes most of the rose cultivars compared at this time can be identified. A dichotomous key useful in identification of rose cultivars was prepared from RFLPs displayed by 3A9 probe.

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Mark Hubbard, John Kelly, Albert Abbott and Robert Ballard

To protect plant patents, rose breeders would benefit from a reliable and sensitive method for differentiating cultivars at the genetic level. Rcombinant DNA technologies are being employed to characterize individual DNA structure of numerous rose cultivars. Restriction fragment length polymorphisms (RFLPs) are being studied to develop a characteristic pattern, or fingerprint for each cultivar. DNA from various cultivars is restriction enzyme digested and the fragments separated by agarose gel electrophoresis. The gel is Southern blotted and hybridized with probes from the rose DNA library to yield RFLPs. RFLPs are being located and will eventually result in a characteristic fingerprint for each cultivar.

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Sriyani Rajapakse, Mark Hubbard, Albert Abbott, John Kelly and Robert Ballard

Restricted Fragment Length Polymorphisms (RFLPs) were investigated in closely and distantly related rose cultivars as means of identifying those cultivars for the purpose of patent protection. A random genomic DNA library was constructed using the cultivar `Confection' and the Escherichia Coli strain JM83 plasmid vector pUC8. Clones with interspersed repeat sequences were then identified by hybridizing restriction digested cloned DNA fragments with nick translated genomic DNA of the rose cultivar `Confection'. Hybridization positive clones were screened for polymorphism by Southern hybridization on restriction digested genomic DNA of various rose cultivars. About 75% of the interspersed repeat copy probes screened revealed polymorphisms. We have identified probes that give fingerprint patterns for rose cultivars. From this information, a dichotomous key which differentiates the rose cultivars examined was prepared. Current research involves screening more probes and rose cultivars for polymorphisms, and examining single copy probes for potential use in RFLP genetic linkage map construction in roses.

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Mark Hubbard, John Kelly, Sriyani Rajapakse, Robert Ballard and Albert Abbott

We have initiated a phylogenetic study using restriction fragment length polymorphisms to examine nuclear DNA variation in a number of Rosa species. Random genomic clones were isolated from the cultivar `Confection'. To generate these clones, genomic DNA was digested with the restriction enzymes Hind III and Eco RI and the resulting fragments cloned into a pUC8 plasmid and transformed into the E. coli bacterial strain JM83. Individual clones from the DNA library were screened for polymorphism by Southern hybridization methods. Those clones displaying polymorphisms were used in combination with one, two, or three restriction enzymes to identify different size restriction fragments. Each fragment was treated as a unit character and was used to generate a phylogenetic tree using the computer program “Phylogenetic Analysis Using Parsimony” (PAUP version 3.0). Results of the studies on the amount of genetic diversity and phylogenetic affinities of Rosa species among the different sections of the subgenus Rosa will be presented.

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Mark A. Hubbard, James A. Flore, John C. Wise and James W. Johnson

European red mite (Panonychus ulmi) populations were monitored in a tart cherry (Prunus cerasus `Montmorency') orchard and the effects on photosynthesis determined. Mites levels were controlled in some trees by miticide applications to establish different cumulative mite*days in the trees. Photosynthetic inhibition caused by insect injury was also simulated by spraying other trees with 78 ppm Terbacil at one of four different times during the season, The mite*days accumulated in 1993 ranged from 937 to 2205, however, there were no differences in single leaf or whole tree CO2 assimilation, chlorophyll a fluorescence, or chlorophyll levels among the different levels of mite damage. Likewise, there were no differences in these same parameters among the Terbacil-treated trees except that photosynthesis was reduced on treated trees for 10-14 days, after which photosynthesis recovered to the level of the controls. There were no differences in yield or fruit quality among any treatments, and cold hardiness and return fruiting characteristics will be measured.