bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed Developmental Temperature Regulation of Thermotolerance in Lettuce
Authors: Sung Yu , Cantliffe Daniel J. , Nagata Russell T.
Published: January 2019

Lettuce (Lactuca sativa L.) seeds can fail to germinate at temperatures above 24 °C. The degree of thermotolerance is thought to be at least partly related to the environment under which the seed developed. In order to study the effects of temperature during seed development on subsequent germination, various lettuce genotypes were screened for their ability to germinate at temperatures ranging from 20 to 38 °C. Seeds of the selected genotypes `Dark Green Boston' and `Valmaine' (thermosensitive), `Floricos 83', `Everglades', and PI 251245 (thermotolerant) were produced at 20/10, 25/15, 30/20, and 35/25 °C day/night temperature regimes in plant growth chambers. Seeds were germinated on a thermogradient bar from 24 to 36 °C under 12 h light/dark cycles. As germination temperature increased, the number of seeds that failed to germinate increased. Above 27 °C, seeds matured at 20/10 or 25/15 °C exhibited a lower percent germination than seeds that matured at 30/20 or 35/25 °C. Seeds of `Dark Green Boston' and `Everglades' that matured at 30/20 °C exhibited improved thermotolerance over those that matured at lower temperatures. Seeds of `Valmaine' produced at 20/10 °C exhibited 40% germination at 30 °C, but seeds that matured at higher temperatures exhibited over 95% germination. Germination of `Valmaine' at temperatures above 30 °C was not affected by seed maturation temperature. The upper temperature limit for germination of lettuce seed could thus be modified by manipulating the temperature during seed production. The potential thermotolerance of seed thereby increased, wherein thermosensitive genotypes became thermotolerant and thermotolerant genotypes (e.g., PI251245) germinated fully at 36 °C. This information is useful for improving lettuce seed germination during periods of high soil temperature, and can be used to study the biology of thermotolerance in lettuce.
Sugar Accumulation and Partitioning in Satsuma Mandarin Tree Tissues and Fruit in Response to Drought Stress
Authors: Yakushiji Hiroshi , Morinaga Kunihisa , Nonami Hiroshi
Published: January 2019

Mechanisms of sugar accumulation in response to drought stress in Satsuma mandarin (Citrus unshiu Marc.) fruit were investigated. Predawn leaf water potentials averaged -0.35MPa for well-watered, -0.60 MPa for moderately drought-stressed, and -1.00 MPa for severely drought-stressed glasshouse-grown 3-year-old trees. Fruit peel turgor and fruit growth of the moderately drought-stressed trees recovered to a similar value to that of the well-watered trees. Photosynthetic rates and stomatal conductance of both moderately and severely drought-stressed trees were significantly lower than those of the well-watered plants. However, the total sugar content per fruit of moderately drought-stressed trees was the highest among the drought treatments. A 13C-labeling experiment showed that 13C distribution in fruit grown under the moderately drought-stressed condition was the highest. These findings indicate that sugar accumulation in fruit was caused by an increase in translocation of photosynthates into fruit, especially into the juice sacs, under drought stress.
Water Status in Relation to Maintenance and Release from Dormancy in Blueberry Flower Buds
Authors: Parmentier Cécile M. , Rowland Lisa J. , Linc Michael J.
Published: January 2019

Three blueberry (Vaccinium section Cyanococcus) genotypes, that have different chilling requirements and levels of cold hardiness, were studied. Depth of dormancy was evaluated and water status was determined, using nuclear magnetic resonance (NMR), throughout the accumulation of chilling that leads to release from dormancy. Among the two highbush cultivars studied, `Bluecrop' (Vaccinium corymbosum L.) was the most dormant and `Gulfcoast' (Vaccinium corymbosum L. x Vaccinium darrowi Camp) was the least dormant. The rabbiteye cultivar `Tifblue' (Vaccinium ashei Reade) had an intermediate dormancy. It appeared that the cultivar with the deepest dormancy had also the highest chilling requirement (CR). The NMR results showed that `Bluecrop' buds had the lowest relaxation times (T2), indicating that water was relatively more bound in `Bluecrop' buds than in the buds of the two other cultivars. Whatever the cultivar, no significant variation of T2s and water content of the buds was noted throughout the accumulation of chilling, even after CRs were satisfied. Within 1 day of forcing (24 °C, long day), there was a shift towards freer water but no change in the water content. Forcing was ineffective in freeing water until the plants received enough chilling to satisfy their CRs.
Hybrid Breakdown in the F1 between Solanum chacoense and S. phureja and Gene Transfer for Leptine Biosynthesis
Authors: Veilleux Richard E. , Miller A. Raymond
Published: January 2019

F1 hybrids between high leptine-producing clones (8380-1, PI 458310 and 55-1) of Solanum chacoense Bitt. and anther culture competent or anther-derived clones of S. phureja Juz. & Buk. that did not produce leptines were generally weak plants that grew slowly and died before flowering. Exceptional hybrids could be found that were capable of completing a life cycle, especially during the hot summer months in the greenhouse. All F1 hybrids produced leptines in the leaves but not the tubers, albeit at lower levels than in the S. chacoense parent. Anther-derived monoploids from the F1 hybrids exhibited a range of leptine production from none to levels approaching the S. chacoense parent. Backcross populations of an F1 hybrid to the S. chacoense and S. phureja parents were examined for leptine production. Backcross hybrids were generally much more vigorous than the F1 hybrids. All of the S. chacoense backcrosses produced leptines ranging from intermediate to high levels; four of the twelve S. phureja backcrosses exhibited low leptine levels. A general dominance of leptine synthesis was therefore exhibited, although the nonleptine-producing parent affected the expression of leptines in the hybrids.
Effects of Scape-injected 1-Aminocyclopropane-1-carboxylic Acid (ACC) on the Vase Life of `Testarossa' Cut Gerberas
Authors: Gerasopoulos D. , Chebli B.
Published: January 2019

`Testarossa' gerbera (Gerbera jamesonii Bolus) scapes were injected with distilled water (control), or 0.3, 0.6, and 0.9 mm ACC at harvest, then held at 20 °C for 15 days in a preservative solution. PAL activity and ethylene production increased within 1 day proportionally to injected ACC. ACC injection reduced bending incidence, inhibited flower scape elongation, enhanced firmness of the flower scapes and increased vase life. Flower scapes treated with ACC reached full maturity 3 days before the end of vase life of the control, which bent before reaching full maturity.
Genetic Relationships and Diversity in Carrot and other Daucus Taxa Based on Nuclear Restriction Fragment Length Polymorphisms
Authors: Vivek B.S. , Simon Philipp W.
Published: January 2019

Current classifications of the genus Daucus are based on morphological and anatomical characteristics. We have used single to low copy nuclear restriction fragment length polymorphisms (nRFLPs) to describe the phylogeny and relationships of eight Daucus species including cultivated carrot (D. carota L.). Parsimony analysis of 247 characters (DNA fragments from 58 probe-enzyme combinations) yielded a tree in which accessions were grouped into three major clades and phenetic analysis using Jaccard's coefficient yielded two major clusters. The phylogenetic relationships from the nuclear RFLP data generally agreed with an earlier morphological classification. Resolution and placement of D. guttatus and D. muricatus were not consistent with the morphological classifications. Molecular variation among carrot inbreds was large.
A Simple, Rapid Extraction and Assay Procedure for NAD+-dependent Sorbitol Dehydrogenase (SDH) in Peach
Authors: Bianco Riccardo Lo , Rieger Mark , Sung She-Jean S.
Published: January 2019

Sorbitol is the major photosynthetic product in peach [Prunus persica (L.) Batsch.]. In sink tissues, sorbitol is converted to fructose via NAD+-dependent SDH. A new procedure is described that allows rapid, simple quantification of SDH activity in growing tissues. The procedure uses only 0.01 to 5 g of fresh tissue per sample, such that a single shoot tip, a single root tip, or ≈5 g of fruit flesh can be assayed for SDH activity. Storage of samples at 4 or -20 °C overnight resulted in significant loss of enzyme activity. Thus, freshly harvested tissues were ground with sand in buffer at 2 °C in a mortar and pestle, and the homogenate was centrifuged at 3000 gn to remove particulate matter and sand. The supernatant was desalted on a Sephadex G-25 column, and the eluent was assayed for SDH activity immediately. Activity was determined by measuring the production of NADH per minute in the assay mixture using a spectrophotometer (340 nm). Tris buffer at pH 9.0 was the best for extraction of peach SDH. Activity of SDH was strongly inhibited by dithiothreitol (DTT) in the extraction mixture and by DTT, L-cysteine, or SDI-158 in the assay mixture, similar to results reported for SDH from mammalian tissues. Peach SDH has a Km of 37.7 mm for sorbitol and a pH optimum of 9.5, similar to those reported for apple (Malus × domestica Borkh.) SDH. Unlike older protocols for SDH activity in plant tissues, the new procedure features reduced sample size (1/10 to 1/100 of that which was previously used), smaller volumes of buffer, fewer buffer ingredients, greatly reduced time for sample preparation, yet comparable or higher values of SDH specific activity. Following the same procedure, SDH activity was also measured in Prunus fremontii Wats., Prunus ilicifolia (Nutt.) Walp., and Marianna 2624 plum (P. cerasifera Ehrh. × P. munsoniana Wight & Hedr.).
Predicting Lettuce Canopy Photosynthesis with Statistical and Neural Network Models
Authors: Frick Jay , Precetti Cyrille , Mitchell Cary A.
Published: January 2019

An artificial neural network (NN) and a statistical regression model were developed to predict canopy photosynthetic rates (Pn) for `Waldman's Green' leaf lettuce (Latuca sativa L.). All data used to develop and test the models were collected for crop stands grown hydroponically and under controlled-environment conditions. In the NN and regression models, canopy Pn was predicted as a function of three independent variables: shootzone CO2 concentration (600 to 1500 mmol·mol-1), photosynthetic photon flux (PPF) (600 to 1100 μmol·m-2·s-1), and canopy age (10 to 20 days after planting). The models were used to determine the combinations of CO2 and PPF setpoints required each day to maintain maximum canopy Pn. The statistical model (a third-order polynomial) predicted Pn more accurately than the simple NN (a three-layer, fully connected net). Over an 11-day validation period, average percent difference between predicted and actual Pn was 12.3% and 24.6% for the statistical and NN models, respectively. Both models lost considerable accuracy when used to determine relatively long-range Pn predictions (≥6 days into the future).
Spur Leaves Increase Calcium in Young Apples by Promoting Xylem Inflow and Outflow
Authors: Lang Alexander , Volz Richard K.
Published: January 2019

The effects of spur leaf removal on xylem sap flows and calcium accumulation in fruit of apple (Malus ×domestica Borkh. `Royal Gala') were determined 56 to 61 days after full bloom. Fruit calcium concentrations were reduced but fruit size was not influenced by partial spur defoliation at bloom. Apples exchanged xylem sap with the tree in daily cycles of flow reversal. The presence of local spur leaves promoted this exchange by accentuating the xylem sap drawn out of the fruit during the day, requiring more to flow back into the fruit at night to replace it. Calcium concentrations were lower in the xylem sap leaving the fruit than in that entering it. The reduced calcium accumulation in the fruit borne on defoliated spurs can therefore be attributed to the reduced volume of xylem sap exchanged between tree and fruit.
Changes in Methanol Evolution and Pectin Methylesterification in Resistant and Susceptible Pepper Leaves Inoculated with Xanthomonas campestris pv. vesicatoria
Authors: Mundodi Suparna R. , Anderson Jeffrey A. , Maness Niels O. , Smith Michael W. , Martin Bjorn , Pierce Marlee L. , Mort Andrew J.
Published: January 2019

The hypersensitive response in resistant plants exposed to incompatible pathogens involves structural changes in the plant cell wall and plasma membrane. Cell wall changes may include pectin deesterification resulting in release of methanol. The time course of methanol production was characterized from `Early Calwonder 20R' pepper (Capsicum annuum L.) leaves infiltrated with the incompatible pathogen, Xanthomonas campestris pv. vesicatoria (Doidge) Dye race 1 (XCV). In the first time course experiment, leaves were infiltrated with either 108 colony-forming units/mL of XCV or water control. Leaf panels (1 × 5 cm) were excised after dissipation of water soaking, then incubated in vials at 24 °C. Headspace gas was analyzed at 6-hour intervals up to 24 hours. The rate of methanol production from resistant pepper leaves infiltrated with XCV was greatest during the first 12 hours after excision. In another experiment, leaf panels were harvested at 6-hour intervals up to 24 hours after inoculation and incubated for 12 hours at 24 °C to determine the relationship between the interval from inoculation to leaf excision and methanol production. The highest rate of methanol production was obtained when the interval between bacterial infiltration and leaf excision was 18 hours. The relationship between methanol release and changes in the degree of methylesterification (DOM) of cell wall pectin was determined in near isogenic lines of `Early Calwonder' pepper plants resistant (20R) and susceptible (10R) to XCV race 1. Cell walls were prepared from resistant and susceptible pepper leaves infiltrated with XCV or water. XCV-treated resistant leaves had 18% DOM and 9.7 nmol·g-1·h-1 of headspace methanol, and the susceptible leaves had 48% DOM with 0.2 nmol·g-1·h-1 methanol. Susceptible and resistant control leaves infiltrated with water had 55% and 54% DOM, respectively, with no detectable methanol production. Increased methanol production in resistant pepper leaves inoculated with XCV coincided with an increase in cell wall pH. Intercellular washing fluid of resistant pepper leaves had a significantly higher pH (6.9) compared to susceptible leaves (pH 5.1) and control leaves infiltrated with water (pH 5.1). Both 10R and 20R pepper leaves infiltrated with buffer at increasing pH's of 5.1, 6.9 or 8.7 had increased methanol production. Since deesterified pectin is more susceptible to degradation, demethylation may facilitate formation of pectic oligomers with defensive signalling activity.
Effects of Plant Tissue and DNA Purification Method on Randomly Amplified Polymorphic DNA-based Genetic Fingerprinting Analysis in Carrot
Authors: Boiteux L.S. , Fonseca M.E.N. , Simon P.W.
Published: January 2019

Seven plant genomic DNA purification protocols were evaluated for genetic fingerprinting analysis using six tissues obtained from inbred carrot (Daucus carota L.) lines. Evaluations included 1) DNA yield, 2) DNA purity, 3) DNA cleavage with HindIII, 4) DNA integrity, and 5) DNA suitability for amplification in a random amplified polymorphic DNA (RAPD) system. Significant differences were observed among tissues and purification methods for the total amount of DNA. An extraction method using CTAB buffer + organic solvents gave the best results in DNA yield, purity, and HindIII cleavage when compared with the other six nonorganic extraction methods. Of the tissues examined, flowers yielded the most DNA (average value = 115 ng of DNA/mg of fresh tissue); followed by seeds (54 ng·mg-1), fresh leaves (48 ng·mg-1), lyophilized leaves (40 ng·mg-1), calli (22 ng·mg-1), and tap roots (4 ng·mg-1). For most of the preparations, the DNA showed no traces of degradation. However, DNA preparations were not consistently accessible to HindIII cleavage in all tissue-extraction method combinations. Uncut DNA was observed chiefly in extractions from flowers and fresh leaves suggesting a tissue-specific adverse effect on restriction endonuclease activity. Differences in RAPD band (amplicon) intensity and number were observed across tissues and DNA extraction methods using identical PCR conditions for RAPD. Callus was the best type of tissue for RAPD-based fingerprinting yielding a consistently higher number of more intense amplicons when compared to the other tissues. In flowers and seeds, only DNA obtained with the CTAB extraction method could be amplified. Polymorphisms deviating from genetic expectations were mainly observed in root and fresh leaf DNA, indicating that some RAPD markers may not present satisfactory levels of reproducibility. Judicious and uniform selection of DNA purification method as well as tissue source for DNA extraction are, therefore, important considerations for reliable RAPD-based DNA fingerprinting analysis in carrot. In addition, our studies allowed the identification of a better combination of procedures for use in routine manipulations of carrot DNA such as RFLP-RAPD-based cultivar fingerprinting, molecular mapping, screening of transgenic plants, construction of genomic libraries, and gene cloning.
Effect of Planting System on Productivity, Dry-matter Partitioning and Carbohydrate Content in Above-ground Components of `Flordaprince' Peach Trees
Authors: Caruso T. , Inglese P. , Sottile F. , Marra F.P.
Published: January 2019

Vegetative growth, fruit yields, and dry matter partitioning within above-ground components were assessed during three growing seasons for trees of an early ripening peach (Prunus persica L. Batsch `Flordaprince' on GF 677 rootstock) trained either to a free standing central leader (930 trees/ha) or to Y shape (1850 trees/ha). Individual trees trained to central leader gave higher fruit yield, had a significantly greater leaf area and accumulated more dry mass in above-ground components per tree than Y shape trees. The training systems did not differ in terms of yield efficiency (yield per trunk cross-sectional area) and leaf area index (LAI), but Y shape trees had a higher harvest index and fruit dry mass per ground area than central leader. Four years after planting, Y shape had 35% higher yield per hectare than central leader. The relative contribution of 1-year-old wood, shoot and leaf to the dry mass of the tree decreased with tree age. Four years after planting the dry matter partitioned to the >1-year-old wood components represented 60% of the total tree mass (excluding fruit) in both the training systems. Central leader trees had the highest relative vegetative growth rate during stage III of fruit development. Most starch depletion occurred from dormancy to pit hardening from the canopy main storage pools (>1-year-old wood), and was higher for central leader than Y shape trees. For the ease of management and the high crop efficiency, the Y shape can be successfully used for peach high density planting systems.
Comparative Abundance of the Large Subunit of Rubisco in Aerial Organs of the Japanese Morning Glory [Ipomoea (Pharbitis) nil] Suggests a Photosynthetic Role for Sepals
Authors: Bassett Carole L.
Published: January 2019

Levels of the large subunit (LSU) of rubisco (ribulose 1,5 bisphosphate carboxylase/oxygenase) were measured in vegetative and floral organs of `Violet' Japanese morning glory (Ipomoea [Pharbitis] nil Roth). Identification of the LSU in polypeptides separated by two-dimensional gel electrophoresis allowed estimation of the relative abundance of this polypeptide in the organs examined. Further quantitation was achieved by immunoblotting protein extracts either alone or in combination with various amounts of extracts from other organs. The amount of LSU decreased in the order leaves > cotyledons > sepals > corollas > androecium, gynoecium. The relative abundance of LSU in sepals (74%) compared to photosynthetically competent organs [leaves (100%) and cotyledons (81%)] suggests that sepals may be photosynthetically competent in supporting development of the other floral organs.
Cultivar Fruiting and Vegetative Response to Nitrogen Fertilizer in Cranberry
Authors: Davenport Joan R. , Vorsa Nicholi
Published: January 2019

Cranberry (Vaccinium macrocarpon Ait.) has the opportunity to partition resources into sexual and/or asexual (stolons) modes of reproduction. Nitrogen status has been shown to impact the degree of stoloniferous growth. To determine whether there is a genotypic response to varying nitrogen levels, six hybrid and four native cultivars were treated with three annual rates of nitrogen fertilizer (17, 34, or 67 kg·ha-1) for 4 years. Fruit yield was determined each year and asexual vegetative growth (stolons) weight was removed and measured in all but the first year of the experiment. Cultivars exhibited different patterns of yield and stolon weight response over the three nitrogen rates. Not all cultivars exhibited significant yield decreases at the high N levels. Vegetative growth (stolon weight) generally increased with increasing N, however, not all cultivars responded similarly over three N rates. Partitioning between yield and stolon production favored fruit yield at the lower N rates in three of the four native cultivars studied (`Cropper', `Early Black', and `Howes'). Yield over N rates was more stable for four of the six hybrid cultivars, which may be the result of greater heterozygosity in hybrids than natives, and/or genetic gain from one breeding and selection cycle, offering increased tolerance to nitrogen stress. This study indicates that genetic variation exists for yield, yield stability, and stolon production relative to nitrogen level, and that genetic gain in cranberry is possible for these traits. Future studies involving cranberry physiology and nutrition should consider the genotypes used.
Accumulation of 1-Aminocyclopropane-1-carboxylic acid (ACC) in Petunia Pollen is Associated with Expression of a Pollen-specific ACC Synthase Late in Development
Authors: Lindstrom Jon T. , Lei Chih-Hsien , Jones Michelle L. , Woodson William R.
Published: January 2019

Mature pollen from Petunia hybrida contains significant levels of 1-aminocyclopropane-1-carboxylic acid (ACC), and this ACC is thought to play a role in pollination-induced ethylene by the pistil. We investigated the developmental accumulation of ACC in anthers and pollen. The level of ACC in anthers was very low until the day before anthesis, at which time it increased 100-fold. A 1.1-kb partial ACC synthase cDNA clone (pPHACS2) was amplified from total RNA isolated from mature anthers by reverse transcriptase, followed by polymerase chain reaction using oligonucleotide primers synthesized to conserved amino acid sequences in ACC synthases. The expression of pPHACS2 mRNA during anther development was correlated with the accumulation of ACC and was localized to the pollen grain. The pPHACS2 cDNA was used to identify the PH-ACS2 gene from a library of genomic DNA fragments from Petunia hybrida. PH-ACS2 encoded an ACC synthase transcript of four exons interrupted by three introns. The ACC synthase protein encoded by the PH-ACS2 gene shared >80% homology with ACC synthases from tomato (LE-ACS3) and potato (ST-ACS1a). A chimeric PH-ACS2 promoter-β-glucuronidase (GUS) gene was used to transform petunia and transgenic plants were analyzed for GUS activity. GUS staining was localized to mature pollen grains and was not detected in other tissues. Despite similarities to LE-ACS3, we did not detect GUS activity under conditions of anaerobic stress or in response to auxin. A series of 5-prime-flanking DNA deletions revealed that sequences within the PH-ACS2 promoter were responsible for pollen-specific expression.
A Poststorage Burst of 6-Methyl-5-hepten-2-one (MHO) May Be Related to Superficial Scald Development in `Cortland' Apples
Authors: Mir Nazir , Perez Rufino , Beaudry Randolph M.
Published: January 2019

`Cortland' apples (Malus ×domestica Borkh.), either untreated or treated with diphenylamine (DPA), were stored for 120 days in air at 0 °C. Peel samples were taken from these fruit immediately after storage, placed in glass vials and incubated for 48 hours, or were isolated from fruit held 2 to 72 hours at 22 °C and incubated in the vials for 2 hours. Emission of 3,7,11-trimethyldodeca-1,3(E),6(E),10-tetraene, known as trans,trans-α-farnesene, or simply α-farnesene, and its oxidation product, MHO, were measured in the vial headspace. α-Farnesene content in the gas phase of vials with peel samples reached a maximal level 2 hours after vials were sealed and was higher in DPA-treated than untreated fruit. The content of α-farnesene in the vial headspace remained unchanged for DPA-treated fruit peel during the 2-day holding period. However, α-farnesene declined rapidly after 10 hours incubation for control samples. Incubating peel samples of control fruit under N2 atmosphere prevented the decline in α-farnesene. The MHO release by the peel of control fruit was rapid during the first 2 hours and continued to increase for 24 hours. In contrast, the MHO released from DPA-treated fruit peels was 8000-fold lower than from peel samples of control fruit. The increase in vapor phase MHO was concomitant with peel browning in controls. For whole fruit held at 22 °C for 2 to 72 hours, cumulative MHO release from fruit peels followed a pattern that was similar to the pattern of superficial scald development in these fruit.
Influence of Pod Stomatal Density and Pod Transpiration on the Calcium Concentration of Snap Bean Pods
Authors: Grusak Michael A. , Pomper Kirk W.
Published: January 2019

Understanding the mechanisms that regulate xylem transport of calcium (Ca) to snap bean (Phaseolus vulgaris L.) pods could allow approaches to enhance pod Ca levels, and thereby improve the value of this food source for humans. Pods of greenhouse-grown plants of `Hystyle', `Labrador', `Tendergreen', `Green Crop', `BBL94', and `Gold Crop' were examined for stomatal density and rates of pod transpiration throughout pod development. Among pods ranging from 6 to 14 mm in diameter, Ca concentration and pod stomatal density varied inversely with increasing diameter in all cultivars; Ca concentration for pods of a given diameter also varied among cultivars. To assess the influence of pod stomatal density on pod transpiration, water loss was measured from detached pods of `Hystyle' and `Labrador', which have high and low pod stomatal densities, respectively. Pod transpiration rates were similar for the two cultivars, being ≈15% the rate measured in leaves under equivalent conditions, and comparable to rates of cuticular transpiration measured in leaves with closed stomates. These results suggest that pod stomates have no role, or have only a limited role, in pod transpiration. Pods of `Hystyle' and `Labrador' were placed in enclosures that maintained constant high- or low-humidity environments throughout pod development. For each cultivar, the high-humidity environment led to lower pod Ca concentrations, demonstrating that pod transpiration does have a significant impact on pod Ca accretion. However, `Hystyle' consistently exhibited higher pod Ca concentrations, relative to `Labrador', suggesting that differences in xylem sap Ca concentration may have been responsible for cultivar differences in pod Ca concentration.
The Effect of Hydraulic Characteristics of Volcanic Materials on Yield of Roses Grown in Soilless Culture
Authors: Raviv M. , Wallach R. , Silber A. , Medina Sh. , Krasnovsky A.
Published: January 2019

Rose (Rosa sp.) plants (`Mercedes') were grown in yellow tuff (YT) (volcanic ash, scoria) and pumice from Italy (PI) and Greece (PG) for which physical and hydraulic characteristics were determined. The differences among the measured retention curves of these materials result in significant differences among their relative hydraulic conductivity functions. The hydraulic conductivity of YT is much higher than that of PI, which is higher than that of PG. The plants were subjected to optimal growth and nutrition conditions. Irrigation was controlled using electronic tensiometers, at suction values well within the range of easily available water: 13 cm for YT and 8 cm for the two pumice types. Nonetheless, yields were significantly higher in YT than in PI; yields were even lower in PG. We suggest that the limiting factor was the dynamic water availability to the plants, which is affected mainly by the unsaturated hydraulic conductivity. The relative hydraulic conductivity of YT at 13 cm is more than an order of magnitude higher than that of PI at 8 cm. The relative hydraulic conductivity of PG at 8 cm is two orders of magnitude lower than that of YT at 13 cm. It seems that the current concept of easily available water, based on a predetermined suction range, independent of the hydraulic characteristics of the media, is not an appropriate parameter for irrigation management in soilless culture. The unsaturated hydraulic conductivity, being a characteristic function of the medium and highly sensitive to moisture variation, indicates better the actual availability of water to the roots. Therefore, it should be used for irrigation control in containers filled with porous substrates.
Coexpression of Potato PVYo Coat Protein and cryV-Bt Genes in Potato
Authors: Li Wenbin , Zarka Kelly A. , Douches David S. , Coombs Joseph J. , Pett Walter L. , Grafius Edward J.
Published: January 2019

The codon-modified cryV-Bt gene (cryV-Bt) from Bacillus thuringiensis subsp. kurstaki Berliner, which is specifically toxic to Lepidoptera and Coleoptera insects, and a potato virus Yo coat protein gene (PVYocp), in which the aphid transmission site was inactivated, were cotransformed into potato (Solanum tuberosum L.) `Spunta' via Agrobacterium tumefaciens Conn. We demonstrated the integration and expression of both genes by molecular analysis and bioassays. All cryV-Bt/PVYocp-transgenic lines were more resistant to potato tuber moth (Phthorimaea operculella Zeller) and PVYo infection than nontransgenic `Spunta'. Four cryV-Bt/PVYocp transgenic lines were equal in potato tuber moth mortality to a cryV-Bt transgenic line, but of these four only two lines were equivalent in PVYo titer levels to a PVYocp-transgenic line. We identified two transgenic lines, 6a-3 and 6a-5, which showed greater resistance to potato tuber moth and PVYo than the other cryV-Bt/PVYocp transgenic lines. This study indicated that multiple genes, conferring insect pest resistance and virus resistance, could be engineered into and expressed simultaneously in a potato cultivar.
Organization of American and Asian Ginseng Germplasm Using Randomly Amplified Polymorphic DNA (RAPD) Markers
Authors: Boehm C.L. , Harrison H.C. , Jung G. , Nienhuis J.
Published: January 2019

Genetic differences among eleven cultivated and eight wild-type populations of North American ginseng (Panax quinquefolium L.) and four cultivated populations of South Korean ginseng (P. ginseng C.A. Meyer) were estimated using RAPD markers. Cultivated P. ginseng population samples were collected from four regions of S. Korea. Cultivated P. quinquefolium population samples were collected from three regions in North America: Wisconsin, the Southeastern Appalachian region of the United States, and Canada. Wild-type P. quinquefolium was collected from three states in the United States: Pennsylvania, Tennessee, and Wisconsin. Evaluation of germplasm with 10 decamer primers resulted in 100 polymorphic bands. Genetic differences among populations indicate heterogeneity. The genetic distance among individuals was estimated using the ratio of discordant bands to total bands scored. Multidimensional scaling of the relationship matrix showed independent clusters corresponding to the distinction of species, geographical region, and wild versus cultivated types. The integrity of the clusters was confirmed using pooled chi-square tests for fragment homogeneity.
Inheritance of Downy Mildew Resistance in Table Grapes
Authors: Brown Maurus V. , Moore James N. , McNew Ronald W. , Fenn Patrick
Published: January 2019

A study was conducted to determine how resistance to downy mildew [Plasmopara viticola (Bert. & Curt.) Berl. & de Toni] is inherited in germplasm (Vitis vinifera L., V. labrusca L., V. rupestris Scheele, and V. riparia Michx.) used for breeding table grapes. Crosses, including reciprocals, among parents possessing different levels of downy mildew resistance were evaluated in 1994 and 1995. The proportion of foliar tissue with sporulation, chlorosis, or necrosis was used to measure resistance. All genotypes were rated for these characters on two separate dates in 1994 and 1995. Hypersensitive flecking was also evaluated in the 1995 seedlings to determine its relationship with downy mildew resistance. Crosses with at least one resistant parent had a larger number of resistant offspring than crosses between two susceptible parents. General combining ability (GCA) effects were highly significant for 1994 and 1995. Specific combining ability effects were significant, but were relatively small compared to GCA, suggesting additive gene action was a primary influence on downy mildew resistance. Heritability estimates for sporulation, chlorosis, and necrosis were the highest at the second rating in 1994 (0.88, 0.74, and 0.57, respectively) and 1995 (0.50, 0.60, and 0.60, respectively). Reciprocal crosses indicated that maternal inheritance did not influence downy mildew resistance. A small percentage of progeny with hypersensitive flecking were identified from the germplasm. Seedlings with the flecking characteristic tended to have lower sporulation, chlorosis, and necrosis ratings earlier in the growing season.
Ear Feeding Resistance of Sweet Corn Inbreds to Pink Stem Borer
Authors: Velasco Pablo , Malvar Rosa A. , Butrón Ana , Revilla Pedro , Ordás Amando
Published: January 2019

Pink stem borer (Sesamia nonagrioides Lef.) is one of the most important insect pests of corn (Zea mays L.) in southern Europe. The objectives of this work were to determine the level of resistance in different sweet corn inbreds and to identify sources of resistance to ear feeding by the pink stem borer. Twenty-eight sweet corn (su1 and su1se1) inbreds and four resistant field corn (Su1Se1) inbreds were evaluated for ear resistance at different sowing dates, under two methods of artificial infestation. There were significant differences between infestation methods for ears with damaged grain, husks, cobs, and shanks. The inbred×infestation method interaction was significant for general appearance of the ear. The most resistant inbreds were identified by using mean comparisons and principal component analysis of ear damage traits. All inbreds were damaged. Hence, resistance was incomplete and in need of improvement. EP59, H3, I5125, IL767b, and V7726 were the most resistant sweet corn inbreds, which did not differ significantly from A635, the most resistant field corn inbred. General appearance of the ear appears to be a good indicator of pink stem borer resistance and can be used in preliminary evaluation. Variability exists in the resistance of these sweet inbreds to the pink stem borer and the use of field corn inbreds may not be necessary in the improvement of resistance, although further research is needed to determine if the sources differ in the pertinent genes conferring resistance.
Ethanol Vapor Vacuum Infiltration of Tomatoes: Morphological Analysis and Effect on Ripening and Eating Quality
Authors: Ratanachinakorn B. , Klieber A. , Simons D.H.
Published: January 2019

Tomatoes (Lycopersicon esculentum Mill. `Bermuda') were vacuum infiltrated at the breaker stage with 25 to 55 mL·L-1 ethanol (EtOH) vapor at a 10 kPa pressure for 5 minutes and then held for a further period before ripening in air at 22 °C. Fruit could tolerate these EtOH vapor concentrations for no longer than 0 to 12 hours after vacuum infiltration, depending on concentration; otherwise skin pitting, uneven ripening and off-flavors resulted. Noninjurious conditions delayed ripening, as judged by color change, by an additional 1 to 5 days compared with 4 days for the control; aroma or flavor were not altered as determined by a trained taste panel, except in extreme conditions where in some cases off-flavors increased. Soluble solids and titratable acidity did not vary, but pH increased by 0.1 units in some treatments. In control fruit EtOH was found only in the gel tissue, and acetaldehyde (AA) was higher in the gel tissue compared with the pericarp and columella, indicating different metabolic behavior of the various tomato tissues. During vacuum exposure, EtOH moved through the stem scar and to a much lesser extent through the epidermis; during subsequent exposure to EtOH more EtOH moved through the epidermis than before, but still less than through the stem scar. AA increased following EtOH uptake, but all increases in EtOH and AA disappeared before fruit ripened.
Occurrence of Sugar Alcohols Determines Boron Toxicity Symptoms of Ornamental Species
Authors: Brown Patrick H. , Hu Hening , Roberts Warren G.
Published: January 2019

The phloem mobility of boron (B) in plants varies dramatically among species. Variations in phloem B mobility occur as a consequence of the presence of sugar alcohols (polyols) in some species but not in others, and these differences in phloem B mobility profoundly affect the expression of B toxicity symptoms. Twenty-four species including common ornamental species varying in sugar alcohol content, were selected to test their response to B toxicity. Species that do not produce sugar alcohols exhibited previously described B toxicity symptoms that include accumulation of high concentrations of B in, and burning of, the tip and margin of old leaves. In the sugar-alcohol-producing species these symptoms were absent, and B toxicity was expressed as meristematic dieback and an accumulation of B in apical tissues. These symptoms have not previously been associated with B toxicity in these species and hence may have been frequently misdiagnosed.
Genotype × Environment Interaction for Resistance to Spider Mites in Fragaria
Authors: Medina José López , Moore Patrick P. , Shanks Carl H. , Gil Fernando Flores , Chandler Craig K.
Published: January 2019

Genotype × environment interaction for resistance to the twospotted spider mite (Tetranychus urticae Koch) of eleven clones of Fragaria L. sp. (strawberries) grown in six environments throughout the United States was examined using two multivariate analysis techniques, principal coordinate analysis (PCA) and additive main effect and multiplicative interaction (AMMI). Both techniques provided useful and interesting ways of investigating genotype × environment interaction. PCA analysis indicated that clones X-11 and E-15 were stable across both low and high environments for the number of spider mites per leaflet. The initial AMMI analysis showed that the main effects of genotype, environment, and their first-order interaction were highly significant, with genotype × environment interaction due mainly to cultivar `Totem' and environment FL94. A second AMMI analysis, which excluded `Totem' and FL94, showed that the main effects of the remaining genotypes, environments, and genotype × environment interaction were also highly significant. AMMI biplot analysis revealed that FL93 and GH93 were unstable environments, but with opposite interaction patterns; and GCL-8 and WSU2198 were unstable genotypes with similar interactions that were opposite those of WSU 2202.
Effects of High-pressure Treatment on Mume Fruit (Prunus mume)
Authors: Baba T. , Como G. , Ohtsubo T. , Ikeda F. , Lizada M.C.C.
Published: January 2019

Physical and physiological changes in mume (Prunus mume Sieb. et Zucc.) subjected to a 10-minute hydrostatic high-pressure treatment at 5, 10, 50, 100, 150, and 200 MPa were investigated. Mume fruit exhibited substantial injury at pressures >5 MPa. All treatments induced color changes, which became more apparent at pressures >100 MPa. Fruit subjected to pressures ≥100 MPa deteriorated and were rendered commercially unacceptable. After transfer to atmospheric pressure all treated fruit exhibited lower CO2 evolution rates compared with control fruit. Only fruit subjected to 5 MPa exhibited an increase (27%) in titratable acidity. Ethylene production rate in mume fruit was very high, but consistently and dramatically decreased after treatment, regardless of the pressure applied. The decline in ethylene production was associated with a decrease in ACC oxidase activity. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Emergence of `Genesis' Triploid Watermelon following Mechanical Scarification
Authors: Duval John R. , NeSmith D. Scott
Published: January 2019

Production of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] transplants is hindered by poor, inconsistent emergence, and frequent seed coat adherence to cotyledons. Seed coat adherence leads to weakened and slow growing plants. High seed costs, coupled with stand establishment problems, discourages transplant producers from growing this crop. Improvement of triploid watermelon emergence will lessen financial risks to growers and transplant producers and will provide a more reliable production system. Mechanical scarification was evaluated as a means to overcome inconsistent emergence and seed coat adherence. Seeds of `Genesis' triploid watermelon were placed in a cylinder with 100 g of very coarse sand (1.0 to 2.0 mm diameter) and rotated at 60 rpm for 0, 6, 12, 24, and 48 hours in a series of experiments. Number of emerged seed was recorded daily, to obtain emergence dynamics. No significant differences were observed in seed coat adherence among treatments. The longest duration of scarification However, enhanced emergence as compared to the control in three of four experiments. These data support earlier suggestions that a thick or hard seed coat is a factor contributing to poor germination and emergence of triploid watermelons.
Flavonoid Composition of Three Genotypes of Dry Bean (Phaseolus vulgaris) Differing in Seedcoat Color
Authors: Beninger Clifford W. , Hosfield George L. , Bassett Mark J.
Published: January 2019

Three dry bean (Phaseolus vulgaris L.) genotypes differing in seedcoat color, mineral brown (P C D J G B v), yellow brown (P C D J G b v), and pale greenish yellow (P C D J g b v), were analyzed phytochemically. Kaempferol 3-O-β-d-glucoside (astragalin) was isolated and identified by nuclear magnetic resonance spectroscopy from all three genotypes, and was the main flavonoid monomer present. Flavonoid polymers (condensed tannins) were detected by thin layer chromatography, but anthocyanins were not detected in the three genotypes. High pressure liquid chromatography analyses indicated that astragalin was present at similar concentrations in pale greenish yellow and mineral brown genotypes, but was significantly lower in yellow brown. Presently, we do not know the functions of the G and B color genes, although the presence of astragalin in the three genotypes studied indicates these genes do not appear to act in a qualitative manner with regard to astragalin production, but may control the amount of astragalin present. Subtle differences in color between these genotypes may be due to the amount and type of tannins which have secondarily polymerized with phenolics and flavonoid monomers.
Genetic Transformation of Iris germanica Mediated by Agrobacterium tumefaciens
Authors: Jeknic Zoran , Lee Stephen P. , Davis Joel , Ernst Richard C. , Chen Tony H.H.
Published: January 2019

A protocol was developed for production of transgenic iris plants (Iris germanica L. `Skating Party') from regenerable suspension cultures via Agrobacterium-mediated transformation. We tested a series of selection agents, and identified hygromycin and geneticin as the most suitable for selecting transformed iris cells. Suspension cultures of iris were cocultured for 3 days with A. tumefaciens LBA 4404(pTOK233) carrying an intron-interrupted uidA (GUS) gene encoding β-glucuronidase, and hpt (hygromycin) and nptII (geneticin) selectable marker genes. Hygromycin- or geneticin-resistant calli having GUS enzyme activity were identified and used to induce plant regeneration. More than 300 morphologically normal transgenic iris plants were obtained in ≈6 months. About 80% of the transformants were GUS-positive and NPTII-positive (paromomycin-resistant). Integration of transgenes into the nuclear genome of iris plants was confirmed by Southern blot analysis. We have, therefore, developed an efficient A. tumefaciens-mediated transformation system for Iris germanica, which will allow future improvement of this horticulturally important ornamental monocot via genetic engineering.
Seed Yield, Floral Morphology, and Lack of Male-fertility Restoration of Male-sterile Onion (Allium cepa) Populations Possessing the Cytoplasm of Allium galanthum
Authors: Havey M.J.
Published: January 2019

The primary source (S cytoplasm) of cytoplasmic-genic male sterility (CMS) used to produce hybrid-onion (Allium cepa L.) seed traces back to a single plant identified in 1925 in Davis, California. Many open-pollinated populations also possess this cytoplasm, creating an undesirable state of cytoplasmic uniformity. Transfer of cytoplasms from related species into cultivated populations may produce new sources of CMS. In an attempt to diversify the cytoplasms conditioning male sterility, the cytoplasm of Allium galanthum Kar. et Kir. was backcrossed for seven generations to bulb-onion populations. The flowers of galanthum-cytoplasmic populations possess upwardly curved perianth and filaments with no anthers, making identification of male-sterile plants easier than for either S- or T-cytoplasmic male-sterile onion plants. Mean seed yield per bulb of the galanthum-cytoplasmic populations was measured in cages using blue-bottle flies (Calliphora erythrocephala Meig.) as pollinators and was not significantly different from one of two S-cytoplasmic male-sterile F1 lines, a T-cytoplasmic male-sterile inbred line, or N-cytoplasmic male-fertile lines. Male-sterile lines possessing either the S or galanthum cytoplasm were each crossed with populations known to be homozygous dominant and recessive at the nuclear locus conditioning male-fertility restoration of S cytoplasm and progenies were scored for male-fertility restoration. Nuclear restorers of male fertility for S cytoplasm did not condition male fertility for the galanthum-cytoplasmic populations. It is intended that these galanthum-cytoplasmic onion populations be used as an alternative male-sterile cytoplasm for the diversification of hybrid onion seed production.