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  • Author or Editor: Roger Sauve x
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Leaf segments of greenhouse-grown Ulmus americana L. plants cultured on a Murashige and Skoog basal salts medium supplemented with 0.22 mg/L thidiazuron formed friable type of callus and regenerated shoots. This friable callus readily formed a cell suspension when the callus was placed in a liquid MS medium containing 2 mg/L 1-naphthaleneacetic acid and 1 mg/L 6-benzylaminopurine. Shoots were regenerated from 3-month-old suspension cell cultures after the suspension cells had been cultured on solid medium. Shoots developed roots on MS medium containing 0.1 mg/L indole-3-butyric acid. Intact plants were successfully established in soil.

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Several studies were conducted to evaluate the effects of cultivar, cutting length, and leaf number on rooting of poinsettia. Cuttings were rooted under mist in a soilless medium with 50 cuttings per treatment. Visual rootball ratings were performed after 3 wk. In the first experiment, rooting of ten poinsettia cultivars was compared. The rooting hormone was 0.1% indole-3-butyric acid (IBA). Rooting of `V-14 Red' and `V-14 Marble' was the highest. `V-17 Pink' and `V-17 Marble' had the highest number of callused cuttings. `V-17 White' produced the highest number of extensively rooted cuttings. `V-14 Pink' (3-lf) cuttings 12 cm long rooted better than 5 cm cuttings. Rooting of (7 cm) 3- and 4-leaf cuttings was higher than rooting of 2-leaf cuttings. `V-14 Pink' cuttings treated with 0.8% IBA or 1% IBA + 0.5% 1-napthaleneacetic acid (NAA) rooted better than with 0.1% or 0.3% IBA.

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Phytophthora cinnamoni infected Rhododendrons subjected to moderate moisture levels had greater survival rates than at the wet or dry levels. We potted rooted cuttings of Rhododendron L. hybrid, “Lee's Dark Purple” in 3 liter containers using a mixture of 3 pine bark: 2 coarse builder's sand: 1 Canadian peat moss (by vol.) and infected them with P. cinnamoni. Tensiometers maintained the moisture levels of the treatments at 0, -5, -10, -15, and -20 kPa. After 90 days, measurements of the plants revealed virtually curvilinear results, with the highest survival rate, plant and root weights at -5 and -10 kPa. Investigation continues on susceptibility of Rhododendrons to P. cactorum, P. cryptogea, P. cinnamoni, and P. citrophthora under wet and dry conditions.

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Twenty-five dogwood accessions (one Cornus kousa, three C. kousa × C. florida hybrids, and 21 C. florida) were characterized using amplified fragment length polymorphism. Among the C. florida accessions, four were named cultivars and 17 were selections from Tennessee State University's dogwood breeding program. Amplified fragment length polymorphism band profiles obtained from 13 EcoRI/MseI (+3/+3) primer pairs showed the presence of high genetic diversity between species and within the C. florida accessions. Each accession was distinctly different from each other, and the resistant clones clustered into distinct groups.

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Mesophyll protoplasts were isolated from a diploid daylily (Hemerocallis cv. `Red Magic') by enzyme digestion with a solution containing 0.5% Pectolyase Y-23, Cellulase R-10 1.0%, Driselase 0.1%, Sorbitol 0.6M and half-strength MS inorganic salts at 60 rpm for 4 h. The protoplasts underwent sustained division to produce multicellular colonies on a MS medium supplemented with 0.5 mg/l NAA and 0.5 mg/1 BA. The optimal plating density for cell division was 5 × 104 cells per ml. Cultures grown in agarose-bead media resulted in higher plating efficiencies that of those in solidified or liquid media. Under the above conditions, formation of colonies occurred in 8 to 11% of the cultured protoplasts. Research is in progress for the production of callus from protoplast-derived colonies and for the generation of plantlets from callus.

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Randomly amplified polymorphic DNA (RAPD) techniques were used to compare the DNA from leaf tissues of nine commercial poinsettia (Euphorbia pulcherrima Wild ex Klotzsch) cultivars. Amplification occurred in 57 out of 60 (95%) tested primers. Nine primers that revealed polymorphisms among cultivars were selected for further evaluation. Forty-eight RAPD bands were scored from these primers, and 33 (69%) were polymorphic. All tested cultivars could be discriminated with seven bands generated from primers OPB7 and OPC13. Results of a UPGMA cluster analysis and principal components analysis placed the nine cultivars into two groups: one group consisted of `Jingle Bells', `Supjibi', and `V-17 Angelika', the other of `V-14 Glory', `Red Sails', `Jolly Red', and `Freedom'. `Lilo Red' and `Pink Peppermint' belonged to the latter group, but were relatively distant from other cultivars in that group. These results indicate that RAPDs are efficient for identification of poinsettia cultivars and for determination of the genetic relationships among cultivars.

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The goal of this study was isolate genes that are regulated by Al treatments of tomato roots growing in vitro. For Al treatment, germinating tomato seeds were plated on a MS agar medium supplemented with 0, 350, and 1200 μM AlCl3 for 30 days. Total RNA was extracted from root tissues and separated on denature formamide gel to check their quantity and quality. Equal amount of total RNA from treatment and control was treated with DNAse I (Genhunter, TN) to remove genomic DNA contamination. cDNA was obtained by reverse transcription using all the regents in RNA Image Kit (Genhunter, TN). The cDNA was amplified using the fluorescently labeled anchor primers (Oligo dT-A, C, G) and 16 random primers. Amplification products were separated by electrophoresis in 6% nondenaturing polyacrylamide gels and DNA bands were observed by scanning the gel on a FMBIOIII scanner. After comparing the band profile on the gel image, fragments of gene that showed changes in intensity compared to control (0 μM AlCl3) were isolated from the gel manually. These bands were re-amplified with the same pair of primers as the original amplification and cloned onto PCR-Trap cloning vector (Genhunter, TN). After DNA sequence analysis and homology comparison with NCBI database, we have identified clone # C01HBa0256E08 on L. esculentum chromosome 01, clone # C10HBa0111D09 on chromosome 10 and clone # LE_HBa-31H5 on chromosome 4.

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Complementary Deoxyribonucleic Acid (cDNA) differential display and reverse Northern dot blot were used to identify genes in Pachysandra terminalis Sieb. & Zucc., a cold-tolerant plant, that are regulated by low temperatures. Rooted cuttings were obtained from stock plants that had been maintained in a greenhouse at 24 °C. These cuttings were subjected to the following cold treatments: 2 weeks at 12 °C, 48 hours at 4 °C, 48 hours at 0 °C, and 4 hours at –1 °C. Following leaf tissue analysis of treated and control plants, some stress-related genes and many novel genes were identified. Northern blot hybridization demonstrated that all novel genes were regulated by the cold treatments.

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The development of scoreable genetic markers in poinsettia will be valuable for cultivar identification and for use in patent protection. In this study, polymerase chain reaction (PCR) and randomly amplified polymorphic DNA (RAPD) techniques were investigated for their feasibility in the identification of poinsettia cultivars. DNA was extracted from leaf tissues using the CTAB method. Thirty-six out of 39 (92.4%) primers amplified poinsettia DNA. The size of the amplified DNA fragments ranged from 140 to 2,000 base pairs. On average, 5.4 bands (range 1 - 13) were obtained per primer. A total of 195 bands were obtained; 49 (25.1%) bands were polymorphic in the 9 tested poinsettia cultivars. All tested cultivars could be discriminated with the banding profiles generated from 2 primers. RADP markers provide a consistently reliable and efficient technique for the identification of poinsettia cultivar.

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A cysteine proteinase gene (DQ403257) with an open reading frame of 1125 base pairs was isolated from Pachysdandra terminalis. The primary translated peptide has a predicted length of 374 amino acids, pI (isoelectric point) of 5.70, and molecular mass of 40.9 kDa. The Peptidase_C1 domain is between residue 141 and 367. The proteinase has a conserved motif Gly-Xaa-Thy-Xaa-Phe-Xaa-Asn in the pro region. Sequence comparison shows that the deduced peptide shares 82% identity with the cysteine proteinase RD19a precursor (RD19) (accession P43296) from Arabidopsis thaliana (L.) Heynh. Real-time quantitative reverse-transcriptase–polymerase chain reaction revealed that the gene is induced by treatments of 1 to 7 days of darkness, 2 hours and 3 to 7 days at 5 °C, and 3 days at 38 °C.

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