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H.J. Cho, B.S. Kim and H.S. Hwang

Of 467 accessions of Capsicum pepper (Capsicum annuum L.) tested for resistance to gray leaf spot, KC321, KC220, KC208, KC47 (PI244670), KC43 (PI244670), KC380, and KC319 were highly resistant to both Stemphylium solani and S. lycopersici, the causal agents of gray leaf spot.

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R.B.H. Wills, M.A. Warton and J.K. Kim

Potato tubers (Solanum tuberosum cv. Sebago) were stored at 20 °C in air containing ethylene at <0.005, 0.01, 0.1, 1.0, or 10 μL·L-1 and the level of sprouting was measured over 35 days. The time for tubers to develop an average of one sprout per tuber was found to linearly increase as the log10 ethylene concentration decreased with the effect present over the whole range of concentration. After 35 days of storage, the number of sprouts/tuber was inversely related to the ethylene concentration, but the weight of sprouts was only lower for tubers held in <0.005 μL·L-1 ethylene. The more numerous sprouts on tubers held in 10 μL·L-1 ethylene were short and thick, while the less numerous sprouts on tubers in 0.01-1.0 μL·L-1 were long, thin, and branched, and resulted in no significant difference in total sprout weight between these concentrations. Reducing the concentration of ethylene in the atmosphere around stored potatoes thus reduced sprouting, but levels <0.01 μL·L-1 are required to minimize both sprout emergence and sprout growth.

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E.J. Ryder, Z.H. Kim and W. Waycott

Three mutant traits for chlorophyll deficiency in lettuce (Lactuca sativa L.), bleached bud, calico-2, and pale green, are inherited as single recessive alleles. Bleached bud is epistatic to another recessive allele, dappled. Calico-2 is epistatic to dappled. Pale green is hypostatic to chlorophyll deficient-3. The Vanguard cd mutant is the same as chlorophyll deficient-3. The light green mutant 8744-1 is the same as light green. Independent inheritance is shown for bleached bud and dappled, calico-2 and dappled, and pale green and chlorophyll deficient-3, respectively.

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C.K. Kim, J.Y. Oh, J.D. Chung, A.M. Burrell and D.H. Byrne

Somatic embryogenesis was initiated from in vitro-grown leaf explants of rose using an induction period of 4 weeks on MS basal medium supplemented with auxin followed by several subcultures on MS basal medium with cytokinin. `4th of July' showed the highest regeneration frequency (24.4%) on 5.3 μm NAA followed by culture on medium containing 18.2 μm zeatin. `Tournament of Roses' produced somatic embryos when cultured for 4 weeks on medium containing dicamba, 2.3 μm followed by three subcultures on medium containing 18.2 μm zeatin. Embryogenic callus matured on MS media containing 0.5 μm NAA, 6.8 μm zeatin, and 2.9 μm GA3. Long-term cultures were established for both cultivars. Somatic embryos germinated on MS medium containing IBA and BA. Silver nitrate (58.8 μm) enhanced shoot formation and germination of somatic embryos. Plants derived from somatic embryos were acclimatized and successfully established in the greenhouse.

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J.D. Chung, B.J. Lee, H.S. Lee and C.K. Kim

Lettuce (Lactuca sativa L.) were transformed using microparticle bombardment with two different genes, alpha-glucuronidase (GUS) gene and Chinese cabbage Glutathione Reductase (GR) gene. The adventitious shoots of cotyledonary explant from 4-day-old seedlings were formed (46.7%) in MS basal media supplemented with 5.0 μm IAA and 1.0 μm 2ip. When 1100 psi helium pressure, 9 target distance, and coating with tungsten 10 microparticles were used and explants were treated with osmoticum-conditioning medium (0.6M sorbitol/mannitol), 4 h prior to and 16 h after bombardment, it was identified by GUS assay that these conditions were the most efficient for transformation of foreign genes into cotyledon tissue of lettuce with particle bombardment. PCR confirmed that the band observed in the transgenic plants were originated from T-DNA tranfer with strong hybridization. The genomic Southern analysis showed that the 1.5-kbp fragment was hybridized with radiolabeled 1.5-kbp GR probe. To know whether the expression of the GR gene can be stably maintained in the next generation, when T2 selfing seeds that were obtained from the transformed mother plants were sowed on MS medium supplemented with 200 μm kanamycin, 70% of seedlings were revealed resistance to kanamycin.

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Monica L. Elliott, J.A. McInroy, K. Xiong, J.H. Kim, H.D. Skipper and E.A. Guertal

Taxonomic diversity of bacteria associated with golf course putting greens is a topic that has not been widely explored. The purpose of this project was to isolate and identify culturable bacteria from the rhizosphere of creeping bentgrass (Agrostris palustris Huds.) at two sites (Alabama and North Carolina) and hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] at two sites (Florida and South Carolina) for a minimum of 3 years with sampling initiated after the construction process. Randomly selected colonies were identified using gas chromatography for analysis of fatty acid methyl ester profiles. Over 9000 isolates were successfully analyzed. When a similarity index of 0.300 or higher was used, the average number of unidentifiable isolates was 38.6%. The two dominant genera in both bentgrass and bermudagrass rhizospheres were Bacillus and Pseudomonas with Bacillus dominant in bermudagrass and Pseudomonas dominant or equal to Bacillus in bentgrass. Other genera that comprised at least 1% of the isolates at all four sites were Clavibacter, Flavobacterium, and Microbacterium. Arthrobacter also comprised a significant portion of the bacterial isolates in the bentgrass rhizosphere, but not the bermudagrass rhizosphere. Overall, there were 40 genera common to all four sites. At the species level, there were five that comprised at least 1% of the isolates at each location: B. cereus, B. megaterium, C. michiganensis, F. johnsoniae, and P. putida. As has been reported for many grasses, we found considerable taxonomic diversity among the culturable bacterial populations from the rhizospheres of bentgrass and bermudagrass grown in sand-based putting greens.

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J.D. Chung, Y.K. Park, S.O. Jee, H.Y. Kim and M.S. Cho

This experiment was conducted to identify the effect of various growth retardants on the growth of Aerides japonicum in vitro. Paclobutrazol was found the most effective retardant for reducing the leaf growth of seedling. Ancymidol and uniconazole also showed retarding effects on leaf growth of one, whereas Daminozide didn't. When growth retardants were added to culture medium, leaf length of seedlings was gradually shortened and leaf width became wider than that of control. However, root length was shorter and number of roots and root diameter were greatly increased. On the contrary, at 0.05 and 0.1 ppm uniconazole, growth of leaf and root were enhanced. It was showed that the possibility of using as an additive for good growth of Aerides japonicum seedling in vitro. The activity of GA-like substances was higher in the portion in which growth of seedlings were promoted. It was identified by anatomical observations that the number of stomata and thickness of cell layer in leaf were increased by treatment of retardants.

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B. S. Kim, E. Y. Shon, H. J. Jeong and Y. S. Lim

Three Korean cultivars, Pungkak, Kalmi, and Subi, were crossed with PI 201234, which has resistance to P. capsici. A backcross breeding program was initiated to incorporate the Phytophthora resistance into the Korean cultivars, but the level of resistance decreased as the backcross round increased. Highly resistant plants occurred frequently in the BC1F2 populations but were rare in the BC2F1 populations. Resistant plants selected in BC1F3 populations had nearly enough recovery of the growth and fruit characteristics of the Korean recurrent parents. Crosses were made between resistant selections in each BC1F2 population. The F1 hybrids showed a considerably increased level of resistance.

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J.H. Lieth, L.R. Oki, P. Ng, M.C. Garcia-Navarro, S.H. Kim and L.-Y. Li

Daminozide is a growth retardant used in potted plant production as a foliar spray to inhibit shoot elongation. It has its greatest inhibitory effect immediately after application, becoming less pronounced thereafter; continued retardation is accomplished by reapplication at 7to 14-day intervals. A model for this retardation effect is useful in developing decision support tools, as well as in optimizing (perhaps minimizing) the use of this growth retardant. Such a model, as developed and described earlier, simulates the effect of a foliar spray application of daminozide at various concentrations on various days during the production cycle. The objective of this work was to validate this model for various varieties of chrysanthemum. Using the model to simulate the effect of one application of daminozide resulted in predicted plant heights very close to the observed heights for most of the varieties tested. Of four methods used to implement the multiple-application effect, two resulted in very good simulation of the observed plant heights. In summary, the model was shown to be valid for all the varieties of chrysanthemum tested.

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Ksenija Gasic and John E. Preece