bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Nodulin Genes in Japanese Pagodatree (Sophora japonica L.) and American Yellowwood [Cladrastis kentukea (Dum.-Cours.) Rudd]
Authors: Foster Carol M. , Graves William R. , Horner Harry T.
Published: February 2019

Early nodulin genes, such as ENOD2, may be conserved and could function as molecular markers for nodulation. Many nodulating and nonnodulating legumes must be analyzed before the role of such genes in nodulation can be determined. Japanese pagodatree and American yellowwood are closely related, ornamental woody legumes. Unsubstantiated reports of nodulation in Japanese pagodatree require confirmation, and American yellowwood has not been observed to nodulate. We investigated the presence of putative ENOD2 genes in these species, and we are studying differential and temporal expression. Genomic DNA of Japanese pagodatree and primers, derived from proline-rich pentapeptide repeats of conserved ENOD2 sequences, were used to obtain a 555-bp PCR fragment. This cloned fragment was used as a probe for Southern and Northern hybridizations. Genomes of Japanese pagodatree and American yellowwood contained sequences that are similar to ENOD2 sequences in other legumes. Treatments with either cytokinin or an auxin transport inhibitor may induce expression of the putative ENOD2 genes. New data on the characteristics of nodulin genes in woody legumes will clarify the nature and evolution of nodulation in legumes and may have implications for developing sustainable nursery production protocols.
Optimizing RAPD Markers for Ginseng Genomic DNA Analysis
Authors: Boehm C.L. , Lee I.K. , Jung G. , Harrison H.C. , Nienhuis J. , Sass M. , Hall Moore
Published: February 2019

Random amplified polymorphic DNA (RAPD) may have utility as genetic markers facilitating selection in ginseng crop improvement. This experiment determined chemical buffer and root tissue-type combinations that yield repeatable bands. The results allow further experiments using RAPD markers for estimating the genetic distance between ginseng landraces, selection for crop improvement, and extensive fingerprinting for use in determining the origin of tissue samples. This experiment determined mean band yields for all combinations of dry, fresh, and powdered root with cetyltrimethylammonium bromide, potassium/sodium ethyl xanthogenate, and urea buffers. The buffers were applied in replication to the tissue-types with other extraction protocol factors constant. Replications were amplified four times with four different primers using constant PCR and agarose gel electrophoretic protocols. Distinct bands were counted in each replication, and the summation of the replication repeats considered an observation. Least squares means for several response variables were analyzed. The most significant difference found was between buffers. The buffers ctab and urea were productive, and the pex was not. Significant difference was found when buffers were crossed with tissue. The applications of urea to fresh root, ctab to dry root, urea to dry root, and ctab to powdered root were productive. Based on these results we conclude 1) urea and ctab are productive when applied to all tissue-types, 2) dry root, which is easily collected and stored, yields sufficient DNA for analysis, and 3) powdered root, often the form of commercial products that might be tested for genetic origin, will yield sufficient DNA for analysis.
Genetic Transformation of Kentucky Bluegrass with the rolC Gene
Authors: Ke Shanqiang , Lee Chiwon W. , Cheng Zong-Ming
Published: February 2019

Coleoptile tissues excised from young seedlings of `Touchdown' Kentucky bluegrass (Poa pratensis L.) were bombarded with the disarmed Agrobacterium tumefaciens strain EHA 101 carrying rolC (from A. rhizogenes), NPT II and GUS genes. These tissues were then cultured on Murashige and Skoog (MS) medium containing 0.2 mg·L–1 picloram, 0.01 mg·L–1 naphthaleneacetic acid (NAA), 150 mg·L–1 kanamycin, and 50 m acetosyringone. Calli formed on this medium within 2 weeks. The regenerated plants from these calli were analyzed for the presence of the GUS and rolC genes by histochemical GUS assay, PCR, and Southern hybridization. Only 3.7% of the regenerants were transformed when determined by the GUS assay. A similar frequency of transformation in the regenerated plants was obtained after bombarding the coleoptile tissues with the DNA isolated from the pGA-GUSGF-rolC plasmid. Most of the putative transformants were either albinos or variegated plants that are composed of both albino and green tissues.
Optimization of Parameters Influencing Biolistic DNA Transformation of Common Bean (Phaseolus vulgaris L.)
Authors: Zhang Zhanyuan , Mitra A. , Coyne D.P.
Published: February 2019

Optimization of parameters influencing biolistic transformation is a crucial stage towards repeatable transformation of common beans. However, there has been no published study on such optimization of this crop species in a helium particle delivery system (BioRad). Using an intron-containing β-glucuronidase (GUS) gene as a reporter, we optimized several critical parameters of biolistic PDS-1000/He delivery system for common bean transformation. The target explant tissues included cotyledons, zygotic embryos, and meristemic shoot tips suitable for organogenesis. Thus, pretreatment of target tissues with osmotic medium containing 0.15–0.25 m mannitol and 0.15–0.25 m sorbitol, positioning of target tissues in 4 cm microcarrier flying distance, the use of 1.6-μm gold particle and high concentration of coating DNA, and bombardment of young immature tissues twice at 2000 psi, etc., significantly increased transformation rate and achieved the best coverage and penetration of the meristemic areas involved in direct shoot organogenesis.
Factors Affecting Transient Gene Expression in Apple Cotyledons following Particle Bombardment
Authors: Yang Hong Y. , Korban Schuyler S.
Published: February 2019

Developing an efficient gene transfer system for apple (Malus ×domestica L.) remains a major objective in genetic engineering efforts of this fruit crop. Transient expression of the uidA gene coding for β-glucuronidase (GUS) and driven by the cauliflower mosaic virus 35S promoter (CaMV35S) has been induced in apple cotyledonary explants of mature seeds by tungsten particle bombardment using the Particle Inflow Gun (PIG). Several factors that affect transient expression of the GUS gene in apple cotyledons were investigated. The gene transfer efficiency was monitored by recording the number of blue spots observed on explants two days following bombardment. Precultivation of cotyledons for 18 hours before bombardment significantly increased the number of blue foci. Of the three different precipitation methods tested including water, 25% PEG, and 60% glycerol, the latter was the most effective for coating DNA onto tungsten particles. Washing DNA-coated tungsten particles with 70% ethanol and resuspending in 100% ethanol significantly enhanced gene delivery to cotyledons. The amount of particles used for each bombardment also influenced GUS expression. About 0.5 mg of particles per shot resulted in the highest number of blue foci. Using larger quantity of particles (i.e., 2 mg) drastically decreased GUS expression probably due to the toxicity of tungsten particles.
Heritability of Nut, Kernel, and Phenological Traits in Hazelnut
Authors: Yao Qiang , Mehlenbacher Shawn A. , Smith David C.
Published: February 2019

The Oregon State Univ. breeding program is developing improved hazelnut cultivars for the kernel market. Most traits of interest are quantitative, yet there is little information available on their heritability. In this study, the heritability of 10 morphological and 4 phenological traits was estimated by regression of offspring means on midparent values. Seedlings from 35 crosses among 41 parents made in 1988 and 1989 were used. The parents represented the wide genetic diversity used in the breeding program. Estimates were all high, ranging from 0.56 for amount of kernel fiber and 0.58 for time of catkin elongation to 0.87 for percent kernel and 0.89 for nut depth.
Inheritance of the Roughskin Character in Peach
Authors: Okie W.R.
Published: February 2019

Pubescence in peach fruit is controlled by the Gg locus, with the homozygous recessive being the glabrous-skinned nectarine. The roughskin character in peach causes the loss of all long hairs on the epidermis of the fruit. Under a microscope short stubs are visible. The fruit is rough to the touch and appears dull rather than shiny as a nectarine would appear. A pleiotropic effect is lack of hairs on the dormant leaf and flower buds, making them noticeably shiny to the naked eye, unlike normal peaches and nectarines. The roughskin character appeared in 3 of 70 seedlings from the cross of Pekin × Durbin. The remaining seedlings all produced normal peaches. Sibling F2 progenies segregated for peach and nectarine, and in one case, for roughskin as well, indicating the cross was valid. Results from numerous crosses and F2 populations indicate this character is controlled by a single recessive gene, which is hereby designated rs. Nectarines homozygous for this gene have glabrous buds, but otherwise appear normal. The origin of the mutation is unclear. Selfed seedlings of Pekin and Durbin have not expressed the recessive form of the gene. Possibly a limb of the Pekin tree (now gone) used for the crosses had mutated to the recessive form at one or both loci. The homozygous roughskin progeny would have then been inadvertent self-pollinations rather than hybrids, since none of them segregated for nectarine.
Development of in Situ and ex Situ Conservation Strategies for Malus Wild Germplasm in Kazakhstan
Authors: Hokanson Stan C. , Forsline Phil L. , McFerson James R. , Lamboy Warren F. , Aldwinckle Herb S. , Djangaliev Aimak D.
Published: February 2019

Malus sieversii, the main progenitor of domesticated apple, is native to areas in Central Asia. To better represent Malus wild germplasm in the USDA–ARS germplasm collections, maintained in Geneva, N.Y., a cooperative project was initiated with the Republic if Kazakhstan to collect and assess that country's wild populations of M. sieversii and to develop more secure in situ reserves to complement ex situ holdings in the United States and Kazakhstan. To date, four exploration trips to the region have included participants from the United States, Kazakhstan, Canada, New Zealand, and South Africa. Four Kazkh scientists have toured USDA–ARS sites, exchanged information, and collected germplasm in the United States greenhouse screens of 1600 have revealed potentially new sources of resistance to apple scab, cedar apple rust, and fire blight. An isozyme analysis of maternal half-sib families from four regions suggests the populations of M. sieversii collected represent a single panmictic population, with over 85% of total genetic variation due to differences among families. The most recent collections in 1995 were directed towards more ecologically diverse regions, including a site (Tarbagatai) at the most northern limit for M. sieversii equivalent to northern Minnesota in the United States. Some trees in this region produced fruit nearly 70 mm in diameter with excellent aroma, firmness, and color. This germplasm is being systematically characterized for horticultural traits, pest and disease resistance, and molecular markers.
Identification of Apple Rootstocks by Fourier Transform Infrared Spectroscopy
Authors: Gaus Alvan , Stushnoff Cecil , McSay Ann
Published: February 2019

Proper identification of apple rootstocks has always been a problem for nurseries and fruit growers. There needs to be a rapid, inexpensive, and repeatable protocol for identification of apple rootstocks. Fourier transform infrared spectroscopy (FTIR), an analytical chemical technique based on infrared laser characterization of molecular bonding energies for biochemical compounds, such as proteins, may provide an answer. Several rootstocks from the 1984 NC-140 apple rootstock trial were compared. Using a BioRad research spectrometer, spectra derived from 1000 scans per freeze dried sample were used to compare the rootstocks. Using Hit Quality Indices (HQI) generated by Lab Calc software, the rootstocks M.7 EMLA, B.9, and a seedling rootstock were compared with themselves, and each of the other two samples. A perfect match gives a HQI of zero. It was found that root cortex tissue could be used to separate these rootstocks from each other, but root xylem tissue was a poor tissue to use for identification.
Evaluation of Grape Germplasm for Downy Mildew (Plasmopara viticola) Resistance as Related to Leaf Pubescence and Stomatal Density
Authors: Brown Maurus V. , Moore James N. , Fenn Patrick
Published: February 2019

Plasmopara viticola infects and sporulates through stomata of susceptible grape leaves. Sporulation, chlorosis, and necrosis ratings were made in 1994 and 1995 on grape selections and cultivars and Vitis species grown in a fungicide-free vineyard. Cellulose-acetate impressions were made of the abaxial leaf surfaces and stomata were carefully counted within a circle 100 μm in diameter under a light microscope. Leaves were rated as either pubescent or glabrous. There were significant differences among genotypes for sporulation, chlorosis, and necrosis for 1994 and 1995, with highly significant correlations over both years. Stomatal densities were significantly different, but there were no correlations among levels of downy mildew and stomata! densities. Pubescent leaves had significantly higher sporulation, chlorosis, and necrosis ratings for downy mildew than glabrous leaves over both years.
Inheritance of Resistance to the Moroccan Watermelon Mosaic Virus in the Cucumber Line TMG-1 and its Relationship to Zucchini Yellow Mosaic Virus Resistance
Authors: Kabelka Eileen , Grumet Rebecca
Published: February 2019

Potyviruses cause severe loss in cucurbit crops. Inbred lines derived from the Chinese cucumber cultivar, Taichung Mau Gua (TMG), have been identified to be resistant to several potyviruses including zucchini yellow mosaic virus (ZYMV), zucchini yellow fleck virus, watermelon mosaic virus, and the watermelon strain of papaya ringspot virus. Recently, an additional virus that infects cucurbits, the Moroccan watermelon mosaic virus (MWMV), has been identified to be a distinct member of the potyvirus group. In this study, we sought to determine if TMG-1 is resistant to MWMV and, if so, examine whether a relationship exists between resistance to MWMV and resistance to ZYMV. Progeny analyses show that TMG-1 is resistant to MWMV and, like resistance to ZYMV, MWMV resistance is conferred by a single recessive gene. Sequential inoculation of progeny possessing resistance to ZYMV followed by MWMV (or MWMV followed by ZYMV) suggests that both resistances are conferred by the same gene, or two tightly linked genes. Additionally, all F3 families derived from F2 individuals selected for resistance to ZYMV, were resistant to MWMV. A second source of resistance to ZYMV, allelic to the TMG-1 source, has been incorporated into the Dutch hybrid Dina. Progeny analyses show Dina to posses a single recessive gene for MWMV resistance. As with TMG-1, no segregation of resistances was observed when ZYMV resistant progeny were inoculated with MWMV (or MWMV followed by ZYMV). Collectively, these results suggest that a single gene, or two tightly linked genes, control resistance to the potyviruses ZYMV and MWMV.
RAPD Linkage Map Based on an Interspecific Cross between Solanum commersonii and Solanum cardiophyllum
Authors: Valverde Roberto , Chen Tony H. H.
Published: February 2019

To generate a linkage map for further genetic analysis of the traits involved in cold hardiness of potato, we are constructing a RAPD-based linkage map using a two-generation interspecific pedigree of Solanum commersonii and S. cardiophyllum, a hardy and non-hardy species, respectively. We initially screened 220 primers of 10-base arbitrary sequences and selected 86 to amplify a total of 577 polymorphic bands: 301 S. commersonii-specific and 276 S. cardiophyllum-specific bands. Segregation of a total of 247 markers was scored on a population of 44 F1 individuals. From these 247 markers, we have identified 117 markers, which segregate 1:1 in the F1 progeny following a test cross configuration. A RAPD linkage map for S. commersonii will be presented.
Tagging a Downy Mildew Resistance Gene in Cucumber Using RAPD Markers
Authors: Horejsi Thomas , Staub Jack
Published: February 2019

Downy mildew in cucumber (Cucumis sativus L.) is a disease caused by Psuedoperonospora cubensis (Berk. and Curt.). Genetic resistance is used to control this disease. However, selection for resistance to downy mildew requires considerable effort. Molecular markers that are closely linked to a gene for downy mildew resistance may be useful for increasing selection efficiency. RAPD (randomly amplified polymorphic DNA) markers are molecular markers that have several advantages including economy, abundance and high rate polymorphism. Two populations, WI 1983 × Straight 8 and ZuDM1 × Straight 8, were used to identify RAPD markers linked to a downy mildew resistance gene. The WI 1983 × Straight 8 population contained 63 F3 families and the ZuDM1 × Straight 8 population contained 90. These F3 families were evaluated for disease reactions in four locations—Wisconsin, South Carolina, Spain, and The Netherlands. Four replications were conducted in Wisconsin and two in the remaining locations. The ranking of susceptible and resistant families was consistent over the locations. Spearman rank coefficients between locations ranged from 0.65 to 0.84. DNA samples from individual F2 plants in each population were combined into two bulks, one resistant and one susceptible, based on the family performance. Then, PCR analysis was performed. Over 100 polymorphic primers were screened using this bulked segregant analysis to find the resistance gene to RAPD genetic linkage.
Recurrent Selection for Specific Combining Ability for Yield in Four Pickling Cucumber Populations
Authors: Cramer Christopher S. , Wehner Todd C.
Published: February 2019

The combining ability (hybrid performance) of breeding lines is often determined to measure selection progress for yield. Plant breeders utilize this information to develop breeding lines with higher combining ability. The objectives of this study were to measure the specific combining ability for yield traits over three selection cycles from four pickling cucumber populations with Gy 14, a popular pickling cucumber inbred; and to determine the change in specific combining ability for yield traits in four populations improved through recurrent selection. Four pickling cucumber populations, North Carolina wide base pickle (NCWBP), medium base pickle (NCMBP), elite pickle 1 (NCEP1), and hardwickii 1 (NCH1), were developed and improved through modified half-sib selection from 1983 to 1992 to improve yield per se and fruit quality in each population. Eleven families were randomly selected from each of 3 selection cycles (early, intermediate, advanced) from each populations and were hybridized to Gy 14. Plants were sprayed with Paraquat to defoliate them and to simulate once-over harvest. The experiment was a randomized complete-block design with 22 replications per population arranged in a split plot with the four populations as whole plots and the three cycles as subplots. The combining ability for fruit quality rating of NCWBP and NCMBP increased as the number of selection cycles increased. Conversely, selection for higher yield per se decreased the combining ability of the NCEP1 population for improved fruit quality. In most instances, the combining ability of each population exhibited a constant response over selection cycles for each measured yield trait.
Genetics Cooperatives on the World Wide Web: An On-line Resource for Breeders and Geneticists
Authors: Ng Timothy J
Published: February 2019

Crop Genetics Cooperatives tend to be grassroots organizations comprised of individuals with interests in the genetics and/or breeding of a specific crop plant species, genus, or family. Activities of Genetic Cooperative often involve publishing informal research reports, compiling linkage maps, and serving as a repository for monogenic variants in the crop(s) of interest. However, information circulation is often limited to the Cooperative's membership since these organizations are rarely affiliated officially with a specific institution. Fortunately, the rapidly increasing capabilities of the World Wide Web (WWW) now allow Genetics Cooperatives to expand their outreach and provide information to anyone with Internet access. The features of WWW also allow frequent updating of information as necessary for items such as genetic maps and gene collections. The Cucurbit Genetics Cooperative (CGC) is typical of many of these organizations, and CGC is in the process of archiving back issues of the CGC Annual Report on WWW while providing current gene listings and mutant collection information to the scientific community. In addition, software such as databases and programs for analyzing genetic studies are available for downloading, and links are provided to genetic resources at other locations around the world. The process and progress of setting up the CGC website will be described, as well as plans for the future.
Yellow-tip, a Cytoplasmically Inherited Trait in Melon (Cucumis melo L.)
Authors: Ray D.T. , McCreight J.D.
Published: February 2019

A new chlorophyll-deficient mutant is the first cytoplasmically inherited trait described in melon. This mutant is characterized by yellow apices with the leaves and stems progressively turning green in color as the branches mature. A protocol is proposed for naming and symbolizing cytoplasmic traits in melon. This mutation is named yellow-tip and symbolized cyt-Yt.
Varietal Effect on Some Vegetable and Reproductive Characters of Pepper (Capsicum annum L. and C. frutescens)
Authors: Makinde M.J. , Olufolaji A.O.
Published: February 2019

Field trials of five selected cultivars each of Capsicum annum and C. frutescens were made to assess variation in yield performances. The later flowering ones C. frutescens grew taller, and the fruit matured late. Atawewe-9 started flowering 86 days after sowing (DAS) and fruited 103 DAS compared to Tatase-1 with 75 and 80 DAS, respectively. The plant heights for these were 36.6 and 42.7 cm, respectively. As the fruit number per plant increased the fruit size decreased within and between the two species of Capsicum.
Tissue Culture and Plant Regeneration of Cowpea (Vigna unguiculata)
Authors: Marsh Lurline
Published: February 2019

Explants (cotyledon, cotyledonary node, second node, hypocotyl, epicotyl, and leaf) of cowpea (Vigna unguiculata) genotypes MN13 and Pinkeye Purple Hull were cultured on Murashige and Skoog basal nutrient medium. The medium was supplemented with 1 mg·L–1 benzyladenine (BA) or 1 mg·L–1 benzyladenine plus naphthalene acetic acid (BA + NAA) or 2 mg·L–1 2,4-dichlorophenoxy acetic acid (2,4-D). Cultures were maintained at 22°C for 1 month, after which they were transferred to 1 mg·L–1 BA + NAA. Cotyledons, hypocotyl, epicotyl, and leaf segments produced only calli after subculturing in BA + NAA. The second node and cotyledonary node explants cultured on the BA or BA + NAA followed by subculture on BA + NAA produced calli, shoots, and roots. The plants were then transplanted to promix but later died.
Plant Regeneration of Allium victorialis var. platyphyllum Makino via Organogenesis and Somatic Embryogenesis
Authors: Lim Hak-Tae , Lee Eun-Ae , Kim Won-Bae
Published: February 2019

This study was conducted to investigate the possibility of obtaining plantlets via somatic embryogenesis and organogenesis as means of in vitro mass propagation in Allium victorialis var. platyphyllum Makino, one of the most popular wild vegetable plants in Korea. Shoots formed directly when bulb explants of A. victorialis were cultured on MS medium containing 0.2 mg·L–1 NAA and 2.0 mg·L–1 zeatin under 16 hours (light)/8 hours (dark) illumination. The use of leaf and shoot tip explants was not successful, largely due to explant senescence in the present of plant growth regulators. Embryogenic calli were obtained from the bulb explants of A. victorialis on MS medium supplemented with 0.2 mg·L–1 NAA, 0.2 mg·L–1 BAP, and 1.0 mg·L–1 picloram after 4–5 weeks of culture in the dark at 27°C. Upon transfer to shoot-induced MS medium containing 0.2 mg·L–1 NAA and 2.0 mg·L–1 zeatin, embryogenic calli gave rise to numerous somatic embryos, which subsequently developed into multiple shoots after 3 months of culture under 16 hours(light)/8 hours (dark) illumination. For root induction, regenerated shoots were transferred to MS medium added with 1.0 mg·L–1 NAA. Regenerants with well-developed roots were potted in an artificial soil mixture of vermiculite (1) and perlite (1).
Direct Shoot Organogenesis of Medicago sativa
Authors: Yang Guochen , Kamp-Glass Marihelen
Published: February 2019

An efficient and reliable protocol of in vitro shoot regeneration must be first established to have a successful genetic transformation. As a member of legume family, alfalfa is very difficult for direct shoot regeneration. There is no published information on direct shoot organogenesis, although success has been well documented on embryogenesis, which must go through callus stage. Different plant growth regulators at various concentrations were evaluated for callus initiation, development, and direct shoot regeneration. Multiple shoots were produced directly from each individual explant. This will provide an efficient means for production of transgenic alfalfa plants. Therefore, genetic transformation of Medicago germplasm will be significantly expedited.
Rapid Micropropagation of xChitalpa tashkentensis
Authors: Richwine Arthur M. , Marquard Robert D.
Published: February 2019

×Chitalpa tashkentensis (Chilopsis linearis × Catalpa bignonoides) is an attractive small tree producing lavender to white orchid like flowers. Micropropagation would allow for the rapid clonal propagation of new hybrids for testing cold hardiness and landscape performance. The rapid growth response of Chitalpa shoot cultures also makes it an excellent subject for the study of in vitro growth parameters of woody plants. Shoot cultures were initiated from shoot tips on Anderson's rhododendron medium with MS vitamins, 3% sucrose, 1 μm BA, pH 5.6 and solidified with 0.6% phytagar. Shoot cultures stabilized rapidly. Two-node microcuttings were placed on modified MS media (200.1 μm Na2 EDTA and 200.5 μm FeSO47H2O), MS vitamins, 3% sucrose, pH 5.6, 0.6% phytagar and supplemented with NAA (0 0.5, 1.5, or 3 μm) in combination with BA (0, 1, 5, 10, 15, 20, 30, or 40 μm). Cultures grown on media supplemented with 1 mm BA produced the longest shoots and the most nodes per shoot. Cultures grown on media supplemented with 10 μm BA produced the most shoots. Microshoots readily rooted on plant growth regulator free MS medium and were easily acclimated.
Adventitious Shoot and Plantlet Formation from Cultured Apple Leaf Explants
Authors: Al-Juboory Karim H. , Al-Niami Jabar H.
Published: February 2019

Leaves of wild apple (Malus domestica Borkh) were excised from in vitro grown shoots transversely cut into halves and plated onto petri dishes containing regeneration media. Cultures were kept in the dark for three weeks before adventitious shoots were observed. Callus from leaf explants produced adventitious shoots after 3 months of in vitro culture. Callus were cultured on Nitsch and Nitsch medium supplemented with a range of BA (0.0–2.0 μm) and NAA (0.0–10 μm). BA at 10 μm combined with NAA (0.5 μm) proved most effective for stimulating shoot proliferation of cultured apple. Plantlets from tissue culture were easily transferred to the greenhouse environment.
A Comparison between Synthetic and Organic Iron Chelators on in Vitro Growth of Nicotiana tabacum Callus Cultures
Authors: Berg Lisa C. , Owen Henry R.
Published: February 2019

Nicotiana tabacum callus growth (fresh weight) was measured after culture in the light (16-hour photoperiod) or in darkness for four different culture media, differing in iron chelate type or concentration. All media contained MS basal medium supplemented with 30 g·L–1 sucrose, 2 mg·L–1 IAA, 0.2 mg·L–1 KIN, and 7 g·L–1 agar, pH 5.8. Three of the media contained iron-metalosate (Albion Laboratories), an organic iron chelate, at 100, 200, and 400 micromolar concentrations, and the fourth medium contained 100 μm Fe-EDTA. Twenty-five culture tubes were prepared for each of the 4 different media concentrations and 2 light treatments (8 treatments total). A 1-cm3 callus explant was used for each treatment and cultured for 56 days at 20°C. About 20-fold increases in callus fresh weight were observed for cultures incubated in light or in darkness. In addition, callus growth was not significantly affected by iron chelate type, suggesting the potential utility of this organic chelator in tissue culture media to alleviate potential problems of light-induced EDTA instability and subsequent IAA inactivation. These cultures are being maintained to examine the influence of iron chelate type on organogenesis.
The Effect of Jasmonic Acid on in Vitro Nodal Culture of Three Potato Cultivars
Authors: Zhang Zhen , Cheng Zong-Ming
Published: February 2019

Jasmonates are a group of native plant bioregulators that occur widely in the plant kingdom and exert various physiological activities when applied exogenously to plants. We investigated the effect of free jasmonic acid (JA) on stem and root growth and tuberization of potato in vitro nodal culture. Nodal cuttings of three potato cultivars, Norchip, Red Pontiac, and Russet Burbank, were cultured in 2.5 × 15 cm test tubes containing either nodal culture (MS with 2% sucrose) or tuber-inducing (MS with 8% sucrose and 11.5 μm kinetin) medium. The media were supplemented with JA at 0, 0.1, 0.5 1.0, 5.0, 10.0 and 50 m. The cultures were maintained under a 16-hour photoperiod at 24°C for 6 weeks. Potato cultivars showed different sensitivities to JA in stem growth. Norchip is the most and Red Pontiac the least sensitive cultivar. On the nodal culture medium, stem length of Norchip was promoted at 0.1–5 μm, and inhibited at 10–50 μm of JA, but that of Red Pontiac was promoted by JA at all concentrations tested. The number of nodes increased significantly on media with JA than that on medium without JA. The number of adventitious roots did not, but the lateral roots increased significantly when JA was added to the medium. On tuber-inducing media, stem length and node number did not appear to be affected by addition of JA to the medium. The number of axillary shoots increased significantly on the media with low concentrations of JA (0.1–5 μm). No microtubers formed on both media from all three cultivars in 6 weeks.
Screening for Root-knot Nematode Resistance in Somaclonal Variants of Solanum quitoense Lam.
Authors: Santamaria Luisa , Kitto Sherry L.
Published: February 2019

Solanum quitoense is a perennial herbaceous plant native to the tropical regions of Colombia and Ecuador. It has attracted the attention of the international market because of the special taste of its fruits and its being a non traditional crop. The main problem in its culture is its susceptibility to root-knot nematodes, Meloido-gyne incognita (Kofoid & White) Chitwood. Two cultivars of S. quitoense were examined, `Baeza' and `Dulce'. The main objective of this research was to develop protocols for proliferation, rooting and establishment, and regeneration and screening for root-knot nematode resistance. S. quitoense was easy to proliferate, root and reestablish without using growth regulators. Regenerants were initiated from petioles and internodal stem sections cultured on MS medium supplemented with BA 1 to 10 mg·L–1. From 420 explants cultured for each cultivar, there were 226 regenerants for `Baeza' and 279 for `Dulce'. Screening of regenerants for root-knot nematode resistance was carried out in the greenhouse with the regenerants of `Dulce'. Twenty-one regenerants, inoculated with 1000 eggs per plant (determined based on a previous experiment), had five or fewer galls after 5 weeks. Follow-up greenhouse and in vitro screening experiments are presently ongoing.
Morphological Development of Pawpaw [Asimina triloba (L.) Dunal] during Seed Germination and Seedling Emergence
Authors: Finneseth C.L.H. , Layne Desmond R. , Geneve R.L.
Published: February 2019

Little scientific information is available describing morphological development of pawpaw during seed germination. To provide this information, a study was designed to outline important developmental stages and describe seedling characteristics within each stage. Stratified pawpaw seeds were sown in vermiculite and germinated at 25°C in a growth chamber. Ten seedlings were randomly chosen and destructively harvested at 5-day intervals starting at radicle protrusion. Length (mm), fresh and dry weight, and percentage of total dry weight were determined for seedling components. Pawpaw seeds have a small rudimentary embryo with all food reserves stored in a ruminate endosperm. Dry weight measurements showed a dramatic reallocation of reserves from the storage tissue to developing seedling parts. Initial embryo length was less than 3 mm, but within 70 days seedlings exceeded 350 mm. Twelve days after planting, simultaneous radicle and cotyledon growth occurred (3.4 and 3.0 mm, respectively), but neither hypocotyl nor epicotyl was visible. Radicle protrusion was observed at 15 days with radicle, cotyledon and hypocotyl lengths increasing to 4.4, 4.0, and 3.2 mm, respectively. Endosperm comprised 99.1% of total dry weight at this stage. The hypocotyl hook emerged after 30 days and endosperm comprised 76.1% of total dry weight. Cotyledons reached maximum length (29.0 mm) at day 40 and the epicotyl was discernible. At 55 days, the seed coat containing cotyledons and residual endosperm abscised and the average radicle, hypocotyl and epicotyl lengths were 182.0, 61.1, and 7.3 mm, respectively. It is suggested that the cotyledons primary function is absorption of food reserves from the endosperm for transfer to the developing seedling.
Postharvest Evaluation of Fresh Cut Sunflower Cultivars
Authors: Gast Karen L.B.
Published: February 2019

Specialty cut flowers are gaining a greater market share of the floral industry. One species that seems to be losing its fad status and again becoming a market mainstay are sunflowers. In response to that demand seed companies are introducing new sunflower cultivars. Little work has been done to evaluate and compare the postharvest life of these new cultivars. A study was conducted Summer 1995 to determine the postharvest life of several cultivars using both water and floral preservatives. Less than half of the cultivars evaluated had an acceptable commercial postharvest life when only water was used. When fresh flower preservatives were used only three of the cultivars evaluated had an unacceptable postharvest life. The addition of floral preservatives significantly increased the postharvest life of more than a third of the cultivars evaluated, but only two thirds of those had their postharvest life increased into the acceptable range. Cultivars found to have an acceptable postharvest life include a wide variety of colors, plant heights and pollenless flowers, giving the grower a wide choice of cultivars for commercial production.
Surfactants Augment Postharvest Pressure Infiltration of Calcium into `Golden Delicious' Apples
Authors: Saftner Robert A. , Buta J. George , Conway William S. , Sams Carl E.
Published: February 2019

The effects of organosilicone and more conventional hydrocarbon surfactants on postharvest radiolabeled calcium (Ca) and on Ca solution infiltration into `Golden Delicious' apples were examined to provide a direct and more efficient pressure infiltration technique to increase fruit Ca concentration. Both radiolabeled Ca infiltration and the proportional increase in fruit Ca estimated by fruit weight gain from Ca solutions of known concentration were significantly enhanced by a range of surfactants having differing chemical structures. Two organosilicone surfactants, Silwet L-77 and Silwet L-7604, known for their greater capacity to lower the surface tension of solutions than conventional hydrocarbon surfactants, were the best among the surfactants tested at augmenting Ca infiltration. Applications of surfactants to fruit were as effective or more effective when used as a pretreatment rather than by mixing with Ca solutions. The applied atmospheric pressure necessary to infiltrate Ca to levels considered sufficient to maintain fruit firmness and resist decay during storage could be lowered in fruit treated with organosilicone surfactants. Postharvest surfactant and Ca treatments may offer a practical means of increasing the Ca concentration of apple fruit.
Glutamic Acid and 5-Aminolevulinic Acid May Function as Precursors of System II Ethylene in Ripening Tomato Fruit
Authors: Rupasinghe H.P.V. , Gladon Richard J.
Published: February 2019

The ethylene biosynthetic pathway has been established as methionine (MET) to S-adenosylmethionine to 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene, and this pathway has been labeled System I. Another pathway to ethylene may exist during synthesis of massive amounts of ethylene, and this system has been labeled System II. Our objective was to evaluate the efficacy of several compounds as possible precursors of System II ethylene in ripening tomato fruit tissue. Discs of `Rutgers' tomato pericarp tissue at the mature green, pink, and red ripe stages were incubated continuously in 10, 25, or 40 mm solutions of MET, ACC, 5-aminolevulinic acid (ALA), homocysteine, glutamic acid (GLU), alpha-ketoglutarate, or citrate buffer (control). The ethylene production rate at 8-hour intervals during a 32-hour incubation period and free and conjugated ACC content at the end of the incubation period were quantified. Fruit discs at the mature green stage treated with MET and ACC exhibited increased ethylene production and increased free ACC content. These results confirmed the role of MET and ACC as the predominant precursors of ethylene during the early stages of fruit development in tomato (System I). At the pink stage (System II); however, ALA increased ethylene production by 75% and free ACC content by 46% over the control, and MET increased ethylene by 27% and free ACC content by 57% over the control. At the red ripe stage, ALA caused a 35% increase and GLU caused a 31% increase in ethylene production over the control. These results suggest that ALA and GLU may be metabolized to ethylene via an unknown pathway during tomato fruit ripening (System II).
Polygalacturonase Isozyme 2 Binding and Catalysis in Cell Walls From Tomato Fruit: Control and B-subunit Effects
Authors: Chun Jong-Pil , Huber Donald J.
Published: February 2019

The high catalytic potential of PG evident in reactions with soluble pectic polymers is typically not expressed in vivo. In this study, the binding and catalytic properties of PG isozyme 2, and the influence of the B-subunit protein, were investigated using cell walls prepared from tomato fruit expressing the B-subunit antisense gene. Cell walls were prepared from mature-green fruit and treated to remove/inactivate endogenous enzymes. Walls were then preloaded with rate-limiting quantities of purified PG 2, and incubated under catalysis-promoting conditions over the range of pH from 4.5 to 6.0. Cell walls of both B-subunit antisense and wild-type fruit retained comparable quantities of loaded PG 2. The enzymic release of pectin from PG-loaded walls was proportional to the quantity of wall-bound PG 2. In walls lacking the B-subunit protein, the quantity of pectin released by a given dose of wall-associated PG was as much as 2-fold higher than from wild-type walls. The B-subunit protein also influenced the extent of pectin depolymerization during ripening. The release of pectin from cell walls during periods of catalysis was not the sole indicator of the range of pectins hydrolyzed. Treating postcatalytic loaded cell walls to inactivate PG, and subsequent extraction of residual wall pectins using 50 mm CDTA solutions solubilized polymers of significantly lower mol mass compared with pectins solubilized directly from nonloaded cell walls.
Respiration of Fresh-cut Carrots Stored in Low Oxygen or High Carbon Dioxide Atmosphere at Various Temperatures
Authors: Izumi Hidemi , Watada Alley E. , Qi Ling
Published: February 2019

Respiration of carrot slices, sticks, and shreds was monitored during storage in air, low O2 (0.5%, 1%, and 2%) or high CO2 (3%, 6%, and 10%) atmospheres at 0, 5, and 10°C. The respiration pattern differed with temperature and type of cuts. At 10°C, the rates of all cuts decreased with time. At the lower temperatures, the rate of sticks and shreds increased with the increase being greater at 5°C. Carbon dioxide production and O2 consumption of all cuts were lower when stored in either reduced O2 or elevated CO2 relative to those in air. Reduction was the greatest with cuts held in 0.5% O2 or 10% CO2 at 0°C. Low O2 was more effective than high CO2 atmosphere in reducing the rate at 10°C, but not at other temperatures. Respiratory quotient (RQ) of shreds were higher when held in low O2 and lower when held in high CO2 relative to those in air. RQ of other cuts were affected, but not consistently. The Q10 of all cuts ranged from 1.9 to 7.4 in the 0 to 10°C range and was lower with cuts in low O2 and greater with cuts in high CO2.
Postharvest Evaluation of Eastern Muskmelon Cultivars
Authors: Lange Diana L.
Published: February 2019

Several leading Eastern muskmelon varieties were evaluated for their postharvest characteristics. The varieties evaluated were `All Star', `Athena', `Eclipse', `Legend', `Quasar', `Starship', and `Superstar'. The fruit were harvested in multiple harvests from 1 July through 10 Aug. 1996. Postharvest measurements taken included soluble solids (%), firmness, rind and flesh color, respiration, flavor quality, damage after drop tests, storage life, and shipping ability. The fruit of each cultivar were harvested at “half-slip” and “full-slip” and fully evaluated at each level of maturity. Most of the cultivars had similar postharvest characteristics, except `Superstar', which had the lowest overall ratings. Firmness ratings were highest for `All-Star', `Athena', and `Legend' and were lowest for `Superstar'. The flavor quality was similar for most cultivars and lowest for `Superstar' fruit. This trial will be repeated in 1996 and promising cultivars will be recommended for midwestern Unites States production.
Characterization of a 23-kDa Protein from the Wood of Cornus sericea, whose Accumulation is Associated with Seasonal Changes in Cold Hardiness
Authors: Sarighausen Eric , Ashworth Edward
Published: February 2019

Deciduous trees vary in their ability to survive low winter temperatures. Among species studied, two distinct responses to freezing have been described: deep supercooling and extracellular freezing. The tissue characteristics that account for these different responses have not been identified, but it has been proposed that properties of the cell wall distinguish species that supercool from those that do not. Our present objective was to analyze proteins from the cell walls of Cornus sericea, an extremely freeze-tolerant species that does not supercool. Twigs were collected throughout the year. The bark was removed, and the remaining wood was frozen in LN2, freeze dried, and ground into a fine powder. Modifications of published protocols were used for the isolation of total proteins and cell wall proteins. The proteins in the cell wall fraction constituted only a small portion of the total proteins in wood ((<2%). SDS gel electrophoresis established at a single band corresponding to a 23-kDa protein was the predominant component in an extract from twigs in winter. The quantity of 23-kDa protein within the cell wall fraction varied with season. Levels were highest in winter, were reduced in spring, not detectable in summer, and increased in fall. Further analysis, using 2D gel electrophoresis, has shown that the 23-kDa band contains several proteins having similar MW and basic PI These proteins are glycosylated, and a partial amino acid sequence of one protein has been obtained.
Mycorrhizal Influence on Transpiration Rates of Detached Leaves of Cowpea, Rose, and Geranium Exposed to Varying Levels of Abscisic Acid (ABA), pH, Calcium, and Phosphorus
Authors: Green Craig D. , Stodola Ann , Augé Robert M.
Published: February 2019

Mycorrhizal colonization can alter stomatal behavior of host leaves during drought. This may be related to an altered production or reception of a chemical signal of soil drying. We tested whether intact root systems were required to observe a mycorrhizal effect on leaf transpiration (E), or whether some residual mycorrhizal influence on leaves could affect E of foliage detached from root systems. Transpiration assays were performed in the presence of several possible candidates for a chemical signal of soil drying. In detached leaves of Vigna unguiculata (cowpea), colonization interacted significantly with ABA and pH in regulating transpiration. Colonization affected E of detached Rosa hybrida (rose) leaves but had no effect on E of detached leaves of Pelargonium hortorum (geranium). In each species tested, increasing the ABA concentration decreased E. In cowpea, calcium appeared to alter stomatal sensitivity to ABA, as well as regulate stomatal activity directly. The pH of the feeding solution affected E in rose, but did not change E independently in cowpea or geranium. Adding phosphorus to the feeding solution did not alter E or the apparent sensitivity of stomata to ABA in any of the test species. Colonization of roots by mycorrhizal fungi can result in residual effects in detached leaves, that can alter the stomatal reception of chemical signals in both rose and cowpea.
Intsia bijuga Is Moderately Tolerant of Flooding
Authors: Marler Thomas E. , Guzman Louann C.
Published: February 2019

Growth and physiological responses of Intsia bijuga trees to flooding were determined in a series of five container experiments to assess the relative tolerance of this species to flooding. The first measurable response to flooding was reduced leaf gas exchange, which began within 5 to 6 days of the onset of flooding. Development of hypertrophied lenticels at the water line and paraheliotropic leaflet movement were evident by 17 days of flooding. Emergence of adventitious roots on the stem above the water line began after about 30 days of flooding. Leaflet abscission was greatly accelerated by flooding. After more than 3 months of flooding, regrowth of roots, stems, and leaves began within two weeks of draining the medium. The data and observations support a relative ranking of moderate flood tolerance for Intsia bijuga.
Effect of Shade on the Growth of Four Turfgrasses
Authors: Liu Guofan , Kobayashi Kent D.
Published: February 2019

Four turfgrasses (Z-3, Seashore Paspalum, Common Bermuda, and Tif dwarf Bermuda) were grown outdoors in pots under different shade conditions (0%, 30%, and 50% shade) from August to December 1995. Dry weight of clippings taken every two weeks was determined. Turfgrass growth in the three shade treatments were significantly different, and the growth of the turfgrasses were highly significantly different. In the 0% and 30% shade treatments, Common Bermuda and Seashore Paspalum grew similarly, and their dry weights were significantly greater than those of Z-3 and Tif dwarf Bermuda. However, under 50% shade, only Seashore Paspalum grew significantly greater than the others. Comparing growth among the shade treatments for each turfgrass, we found no significantly differences. Only Common Bermuda grew significantly less under 50% shade than under 0% and 30% shade. Common Bermuda is good for golf courses because of its fast growth and attractiveness. Seashore Paspalum can be used for home lawns because of its vigorous growth and shade tolerance. Z-3 turfgrass, an attractive new variety for home lawns, despite its slow growth, is tolerant of different shade conditions.