bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Analyses of Heliconia Species and Cultivars with Randomly Amplified Polymorphic DNA (RAPD) Markers
Authors: Kumar Prakash P. , Yau Janice C.K. , Goh Chong Jin
Published: January 2019

Many Heliconia species are polymorphic with a large number of cultivars. Cultivar identification has been primarily based on morphological differences of the flowers and inflorescences. A protocol was developed to extract DNA from Heliconia leaves and to analyze genetic variation using RAPD. The percentage genetic similarities among Heliconia species, cultivars, and hybrids were determined. Data from 11 primers indicated that the RAPD technique is useful in distinguishing species and cultivars of Heliconia. Using a single 10-mer primer (OPA 18), we were able to generate distinct RAPD profiles for 16 cultivars of H. psittacorum L.f. grown at the Jurong BirdPark, Singapore, a Heliconia Society International depository. Hence, the characteristic profiles generated by RAPD may be used as additional DNA markers for classifying different species and cultivars of Heliconia. The phylogenetic tree derived from the RAPD data showed that all the 16 cultivars examined are closely related to each other, thus providing the first genetic evidence that this large group of cultivars has a common genetic background. Moreover, two triploid cultivars of H. psittacorum—`Iris' and `Petra'—showed identical RAPD profiles with 10 different primers in agarose and polyacrylamide gels, suggesting that they are of the same genotype.
Using Simple Sequence Repeats (SSRs) for DNA Fingerprinting Germplasm Accessions of Grape (Vitis L.) Species
Authors: Lamboy Warren F. , Alpha Christopher G.
Published: January 2019

The USDA-ARS Vitis genetic resources collections in Geneva, N.Y., and Davis, Calif., contain ≈3600 accessions of >35 species. Accurate and unambiguous identification of these grapes is essential for efficient and effective use of this germplasm. Previous workers have successfully used polymerase chain reaction (PCR)-generated SSRs to fingerprint cultivars of the wine and table grape species, V. vinifera. Building on this work, we conducted a test of five previously characterized SSR loci on 110 accessions of 25 grape taxa (21 Vitis species and 4 hybrids) to determine if they would satisfy our need for identifying cultivars within the USDA-ARS grape collections. Scorable SSR fragments were produced with all 550 primer-accession combinations, with no null loci observed. The loci were highly polymorphic, with 16 to 38 different alleles found at a locus. Heterozygosity values ranged from 0.464 to 0.818, while gene diversity values ranged from 0.875 to 0.955. Discrimination power at a locus varied from a low of 0.947 to a high of 0.987. Combined discrimination power of all loci was effectively 1.000, with 2 chances in 100,000,000 that two sexually, independently derived grape accessions would not be distinguishable using this set of five SSR loci. Two plants in the study that had previously been classified as belonging to different grape species were shown to have identical SSR fingerprints, showing that they almost certainly possessed the same genotype. Because SSR markers are codominant and highly polymorphic and SSR loci are generally conserved across a range of related species, we strongly recommend SSRs for fingerprinting not only grape, but other clonal genetic resources collections as well.
Effects of Supplemental Light Duration on Greenhouse Sweet Pepper Plants and Fruit Yields
Authors: Demers Dominique-André , Gosselin André , Wien H. Chris
Published: January 2019

Sweet pepper (Capsicum annuum L.) plants were grown under natural or supplemental lighting that extended thephotoperiods to 16, 20, or 24 hours. Increasing the photoperiod to 16 and 20 hours increased pepper plant yields, but continuous light (24 hours) decreased yields compared to the 20-hour photoperiod. In a second experiment, plants were exposed to a photoperiod of 14 or 24 hoursand either pruned to one fruit every four nodes or not pruned. During the first weeks of treatments, plants grown under continuous light had higher shoot mass (fresh and dry) and yields. After 7 to 8 weeks of treatments, plants under continuous light grew more slowly than plants exposed to a 14-hour photoperiod. At the end of the experiment, shoot mass and yields of plants grown under a 14-hour photoperiod were equal to or higher than plants under continuous light. So, it seems possible to provide continuous lighting for a few weeksto improve growth and yields. Limiting the number of fruit per plant increased shoot mass and decreased yields, but had no effect on the general response of pepper plants to photoperiod treatment. Leaf mineral composition was not affected by photoperiod treatment, indicating that reduced growth and yields under continuous light were not due to unbalanced mineral nutrition. Leaf starch and sugar contents were increased under continuous light. However, fruit pruning treatments did not modify the pattern of starch and sugar accumulation under the different photoperiod treatments. Reduced growth and yields measured under a 24-hour photoperiod are probably explained by starch and sugar accumulation in leaves as a result of leaf limitations rather than a sink limitation.
Modeling Shoot-tip Temperature in the Greenhouse Environment
Authors: Faust James E. , Heins Royal D.
Published: January 2019

An energy-balance model is described that predicts vinca (Catharanthus roseus L.) shoot-tip temperature using four environmental measurements: solar radiation and dry bulb, wet bulb, and glazing material temperature. The time and magnitude of the differences between shoot-tip and air temperature were determined in greenhouses maintained at air temperatures of 15, 20, 25, 30, or 35 °C. At night, shoot-tip temperature was always below air temperature. Shoot-tip temperature decreased from 0.5 to 5 °C below air temperature as greenhouse glass temperature decreased from 2 to 15 °C below air temperature. During the photoperiod under low vapor-pressure deficit (VPD) and low air temperature, shoot-tip temperature increased ≈4 °C as solar radiation increased from 0 to 600 W·m-2. Under high VPD and high air temperature, shoot-tip temperature initially decreased 1 to 2 °C at sunrise, then increased later in the morning as solar radiation increased. The model predicted shoot-tip temperatures within ±1 °C of 81% of the observed 1-hour average shoot-tip temperatures. The model was used to simulate shoot-tip temperatures under different VPD, solar radiation, and air temperatures. Since the rate of leaf and flower development are influenced by the temperature of the meristematic tissues, a model of shoot-tip temperature will be a valuable tool to predict plant development in greenhouses and to control the greenhouse environment based on a plant temperature setpoint.
Influence of Simulated Shipping and Rooting Temperature and Production Year On Easter Lily (Lilium longiflorum Thunb.) Development
Authors: Erwin John E. , Engelen-Eigles Gerard
Published: January 2019

Interaction between simulated shipping and rooting temperature and harvest year was studied on Lilium longiflorum. Bulb dormancy and maturity appear to be separate phenomenon and are affected by temperature differently. Shoot emergence (an indicator of release from dormancy) was hastened by 10 °C shipping and 10 to 20 °C rooting temperatures in both years. Flower induction was affected differently by simulated shipping and rooting temperatures during 1992 and 1993, indicating that bulb maturity differed between the 2 years. Final leaf and flower number decreased because of shipping or rooting temperature, but only when bulbs were mature and received cool temperatures (<16 °C) before a 6-week vernalization treatment. Immature bulbs (at harvest) are unresponsive to vernalizing shipping and rooting temperatures. Prevernalization handling temperature and vernalization treatment length should vary with year based on degree of bulb maturity to achieve consistency in final morphology. Internode length is associated more with the time elongation is suppressed after dormancy is broken than with flower induction (where internode length increases as the length of time elongation is suppressed after breaking of dormancy increases).
Inheritance and Linkage Relationships of Melon (Cucumis melo L.) Isozymes
Authors: Staub Jack E. , Meglic Vladimir , McCreight James D.
Published: January 2019

Nineteen polymorphic and eleven monomorphic isozyme loci were identified in thirteen enzyme systems in a survey of four-hundred melon (Cucumis melo L.) accessions. Segregation of allozymes in F2 and backcross (BC) families for isozyme loci agreed with the expected 1:2:1 and 1:1 segregation ratios (P <0.01). Eleven isozyme loci were linked and were integrated to form a map containing two linkage groups spanning 98 cM with a mean linkage distance of ≈9 cM. Linkage groups (A and B) contain the following loci in the order: A Fdp-2, Pgd, Pgm, Mpi-1, Idh, and Ac, and B Pep-gl, Mdh-2, Mdh-4, Mdh-5, Mdh-6. The remaining eight loci (Acp-1, Acp-4, Ak-4, Fdp-1, Gpi, Mpi-2, Pep-la, and Pep-pap) segregated independently. The isozyme map constructed in this study provides genomic information for future linkage studies with economically important traits and concensus map construction through map merging.
Navel Orange Tolerance to Heat Treatments for Disinfesting Mexican Fruit Fly
Authors: Shellie Krista C. , Mangan Robert L.
Published: January 2019

Navel orange [Citrus sinensis (L.) Osbeck] was exposed to moist, forced air at 46 °C for up to 4.5 hours or 50 °C for 2 hours, or immersed for 3 hours in water at 46 °C. Quality attributes of heated and nonheated fruit were compared after 4 weeks of storage at 7 °C and 1 week at 23 °C. The flavor of oranges immersed in water was rated significantly inferior to fruit heated in air and fruit that were not heated. Oranges immersed in hot water also developed a higher incidence of decay during storage than oranges heated in air or nonheated control fruit. The flavor of oranges exposed to moist, forced air at 46 °C for up to 4.5 hours was rated by preference panelists as similar to nonheated controls, even though heated fruit had a significantly lower amount of titratable acidity and a higher ratio of sugar to acid. Fruit exposed to high-temperature forced air developed less decay during subsequent storage than nonheated control fruit. Texas `N33' navel oranges tolerated exposure to forced air at 46 °C for up to 4.5 hours without deleterious effects on fruit market quality.
Temperature Affects Postharvest Color Change of Apples
Authors: Dixon Jonathan , Hewett Errol W.
Published: January 2019

Loss of green color (yellowing) in apples (Malus ×domestica Borkh.) is due to chlorophyll breakdown, an enzyme-mediated reaction conforming to first-order kinetics. Nondestructive measurements of yellowing, using a tristimulus chromameter, were related to chlorophyll content for `Cox's Orange Pippin' and `Granny Smith' apples stored at temperatures of 0 to 35 °C. Yellowing determined by rate constant (k) of total chlorophyll and changes in hue angle, as a function of temperature, increased slowly from 0 to 5 °C, increased exponentially from 5 to 20 °C, reached a maximum from 20 to 24 °C, then declined at higher temperatures. Values of k and the rate of change of hue angle were characterized by a modified Arrhenius equation. `Cox's Orange Pippin' apples harvested early had lower k and lower rates of hue angle change than late-harvested fruit. Values of k and hue angle change of `Granny Smith' apples differed between years but not between harvests. The method used to characterize the relationship between yellowing and temperature may describe changes in other important quality attributes of apple fruit during storage and shelf life and help evaluate the efficacy of cool-chain handling and storage systems.
Nondestructive Sonic Measurement of Kiwifruit Firmness
Authors: Abbott Judith A. , Massie David R.
Published: January 2019

Firmness is a critical quality characteristic in kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson] marketing. The industry seeks a nondestructive method for firmness sorting. We measured sonic vibrational responses of 149 kiwifruit over the range 0 to 2000 Hz and compared them with Magness-Taylor (MT) penetrometer values. Sonic resonant frequencies and mass were combined to calculate a sonic stiffness coefficient. Coefficients of determination (r2) for sonic stiffness coefficients versus MT slope and log of MT maximum force were 0.88 and 0.86, respectively. Sonic stiffness coefficients provided good to excellent classification of kiwifruit into two or three firmness categories based on MT maximum force values. A combination of amplitudes at several specific sonic frequencies selected by stepwise discriminant analysis or regression tree analysis also provided successful sorting algorithms. Identification of soft kiwifruit was 89% to 96% accurate and of firm kiwifruit 83% to 91%. These conclusions are based on a rather small sampling of kiwifruit of a single source and size, but the results clearly indicate the potential of a nondestructive firmness measurement based on sonic frequency vibrations.
Lactate Dehydrogenase in Fresh-cut Carrot Shreds Stored under Low Oxygen Atmosphere
Authors: Kato-Noguchi Hisashi
Published: January 2019

Carrot (Daucus carota L.) root shreds were stored under a continuous flow of 0.5% and 2% O2 (balance N2) or air at 5 °C to investigate the effect of low O2 atmosphere on respiratory metabolism, particularly on lactate dehydrogenase (LDH) activity and its isozyme composition. Low O2 atmospheres caused a decrease in CO2 production and an increase in lactate concentration and LDH activity compared to air. By day 2, CO2 production rate decreased 0.4- and 0.5-fold, lactate increased 3.5- and 2.2-fold, and LDH activity increased 2.3- and 1.7-fold in carrot shreds stored in 0.5% and 2% O2, respectively, compared to samples in air. Based on nondenaturing electrophoresis, LDH isozyme composition analysis revealed five bands consisting of a tetrameric enzyme with subunits encoded by two different Ldh genes. Changes in staining intensity of the isozymes indicated that the increase in LDH activity in carrots under low O2 atmospheres resulted from increased enzyme synthesis and that there was preferential induction of one Ldh gene. These results suggest that lactic acid fermentation may be accelerated more under 0.5% than 2% O2 atmospheres due to greater expression of the Ldh genes.
Physiological and Molecular Responses of Aeroponically Grown Tomato Plants to Phosphorus Deficiency
Authors: Biddinger Eric J. , Liu Chunming , Joly Robert J. , Raghothama K.G.
Published: January 2019

Phosphorus is one of the essential but limiting nutrients in nature. In this study, we link the physiological changes occurring under phosphate (Pi) starvation to gene expression. Roots of aeroponically grown tomato (Lycopersicon esculentum L.) plants were sprayed intermittently with nutrient solutions containing varying concentrations of P. Decreasing the concentration of Pi in the nutrient solution resulted in reduced biomass production and altered the tissue concentration of nutrients in roots and shoots. Phosphorus starvation increased the root:shoot biomass ratio and decreased net CO2 assimilation and stomatal conductance. Phosphorus concentrations in roots and shoots decreased with decreasing concentration of Pi in the nutrient solution. Pi-deficient plants had a higher concentration of Ca in roots and Mg in shoots. Expression of the Pi starvation-induced gene, TPSI1, persisted even after 3 weeks of Pi starvation. The transcript accumulation in leaves was found to be a specific response to Pi starvation and not to the indirect effects of altered N, K, Fe, Mg, or Ca status. Accumulation of transcripts was also observed in stem and petioles, suggesting a global role for TPSI1 during Pi starvation response of tomatoes.
Recovery and Longevity of Cryopreserved Dormant Apple Buds
Authors: Forsline Philip L. , Towill Leigh E. , Waddell John W. , Stushnoff Cecil , Lamboy Warren F. , McFerson James R.
Published: January 2019

Clonally propagated crops, unlike seed-propagated crops, require intense and costly maintenance, generally in ex situ field gene banks. Consequently, large germplasm collections of tree species especially, are difficult to conserve in a well-replicated fashion and are vulnerable to damage from environmental stresses. Accordingly, long-term storage in liquid nitrogen presents a viable conservation alternative. To assess effectiveness of one approach to cryopreservation, dormant buds from 64 apple (Malus ×domestica Borkh. and other Malus spp.) accessions were collected and preserved in liquid nitrogen using a dormant-vegetative-bud method. Buds were retrieved from liquid nitrogen storage, rehydrated, and grafted onto rootstocks to determine survival. Mean recovery was 76% for 40 cold-hardy accessions, 66% for 20 moderately cold-hardy accessions, and 24% for four cold-tender accessions (range: 16% to 100%). Only four accessions had ≤25% recovery while 54 accessions had ≤50% recovery and 35 accessions had ≤75% recovery. No significant decline in recovery of these accessions by bud grafting occurred after 4 years of liquid nitrogen storage.
Genetic Characterization and Relatedness among California Almond Cultivars and Breeding Lines Detected by Randomly Amplified Polymorphic DNA (RAPD) Analysis
Authors: Bartolozzi F. , Warburton M.L. , Arulsekar S. , Gradziel T.M.
Published: January 2019

Almond [Prunus dulcis (Mill.) D.A. Webb, syn. P. amygdalus, Batsch; P. communis (I.) Archangeli] represents a morphologically and physiologically variable group of populations that evolved primarily in central and southwest Asia. California cultivars have been developed from highly selected subgroups of these populations, while new breeding lines have incorporated germplasm from wild almond and closely related peach species. The genetic relatedness among 17 almond genotypes and 1 peach genotype was estimated using 37 RAPD markers. Genetic diversity within almond was found to be limited despite its need for obligate outcrossing. Three groupings of cultivar origins could be distinguished by RAPD analysis: bud-sport mutations, progeny from interbreeding of early California genotypes, and progeny from crosses to genotypes outside the California germplasm. A similarity index based on the proportion of shared fragments showed relatively high levels of 0.75 or greater within the almond germplasm. The level of similarity between almond and the peach was 0.424 supporting the value of peach germplasm to future almond genetic improvement.
A Third Recessive Allele, stpmic, for Seedcoat Pattern at the Stp Locus in Common Bean
Authors: Bassett Mark J.
Published: January 2019

The inheritance of a seedcoat pattern having white micropyle stripe (WMS) on a colored background was studied in two common bean (Phaseolus vulgaris L.) accessions from Centro Internacional de Agricultura Tropical—G12606 and G07262. The WMS character from G12606 was backcrossed into the recurrent parent 5-593, which has black seedcoats. Test crosses of the derived WMS stocks (BC1 and BC2) with genetic tester stocks stp (stippled seedcoat) BC2 5-593 and stphbw (flowers with half banner petal white) BC3 5-593, respectively, demonstrated in F1 and F2 progenies that WMS is controlled by an allele at the Stp locus. The gene symbol stpmic is proposed for the allele expressing the WMS character. The dominance order at the Stp locus is Stp > stpmic > stphbw > stp. Although stp and stphbw each produce a different color pattern on flowers, stpmic does not produce patterned flowers. A selection from accession G07262 with a long, white micropyle stripe was crossed with 5-593 to derive a stock named F3 stpmic long micropyle stripe, which was then crossed to the genetic tester stock t z virgarcus BC2 5-593 to produce F1 and F2. Expression of the long micropyle stripe was controlled by the interaction of t and stpmic in the genotype t Z stpmic. The triple recessive interaction from genotype t z stpmic was also observed.
Distribution of Sugars and Related Enzymes in the Stem and Blossom Halves of `Valencia' Oranges
Authors: Song Kwan Jeong , Echeverria Ed , Lee Hyoung S.
Published: January 2019

The distribution of sugars (sucrose, glucose, and fructose) and related enzymes between the stem and the blossom halves of `Valencia' oranges [Citrus sinensis (L.) Osbeck] was determined at three stages of fruit development. The blossom half contained significantly higher concentrations of sugars during later stages of development and maturation (12% and 20%, respectively). Neither the enzyme marker for sucrose synthesis [sucrose-phosphate synthase (SPS)] nor enzymes of CO2 fixation (NADP-malic enzyme, PEP carboxylase, and PEP carboxykinase) were significantly different between the halves. Sucrose synthase (SS), the enzymatic marker for sink strength, had significantly higher activity in the blossom half during later stages of fruit development when rapid sugar accumulation takes place. These data suggest that differential distribution of sugars between the stem and the blossom halves of citrus fruit is, in part, the result of differential sink strength.
Volatile Compounds Emitted by `Gala' Apples following Dynamic Atmosphere Storage
Authors: Mattheis J.P. , Buchanan D.A. , Fellman J.K.
Published: January 2019

Fruit quality and volatile compounds produced by apple fruit (Malus ×domestica Borkh. `Gala') were characterized following regular atmosphere (RA) or controlled atmosphere (CA) storage at 1°C. Static CA conditions were 1, 1.9, 2.8, or 3.7 kPa O2. Fruit stored under dynamic CA conditions were exposed to ambient air 1, 2, or 3 days per week for 8 hours then returned to 1 kPa O2. All CA treatments included 2 kPa CO2. Ethylene production was reduced following CA storage plus 1 day at 20°C compared with apples stored in RA. Apples stored in static 1 kPa O2 and the dynamic treatments had lower ethylene production compared with apples stored in 1.9 to 3.7 kPa O2 after 90 and 120 days. Ethylene production by apples from all CA treatments recovered during a 7-day poststorage ripening period at 20°C. Ester production was reduced following CA at 1 kPa O2 after 60 days compared with RA-stored fruit. Production of butyl acetate by apples stored in 1 kPa O2 static CA was 29%, 30%, and 7% of that produced by RA-stored fruit after 60, 90, and 120 days storage plus 7 days at 20°C. Amounts of 2-methylbutyl acetate were not affected by CA storage, however, production of other 2-methylbutyrate esters was reduced following 1 kPa O2 storage. Ester production increased with O2 concentration after 90 days in storage. The dynamic treatments resulted in greater ester emission after 120 days storage plus 7 days at 20°C compared with apples stored in static 1 kPa O2. Production of 1-methoxy-(2-propenyl) benzene by apples subjected to dynamic treatments was also higher after 120 days storage plus 7 days at 20°C compared with apples stored in RA or static CA. No differences in firmness, titratable acidity or soluble solids content were observed between apples stored in 1 kPa O2 and the dynamic treatments. Firmness and titratable acidity were maintained better by dynamic treatments compared with static atmospheres containing > 1 kPa O2.
Scanning Electron Microscopy of Floral Initiation in Sweet Cherry
Authors: Guimond Charlotte M. , Andrews Preston K. , Lang Gregory A.
Published: January 2019

Flower initiation and development in `Bing' sweet cherry (Prunus avium L.) was examined using scanning electron microscopy. There was a 1- to 2-week difference in the time of initiation of flower buds on summer pruned current season shoots (P) compared to buds borne on unpruned shoots (U) or spurs (S). By late July, this difference was obvious in morphological development. The P buds had already formed floral primordia, while the S and U buds showed little differentiation in the meristem until early August. In general, buds from unpruned shoots were similar developmentally to spur buds. By late August, primordial differentiation was similar in the buds from all the wood types; however, buds from pruned shoots were significantly larger (838 μm) than buds from spurs (535 μm) and unpruned shoots (663 μm). Early summer pruning may shift allocation of resources from terminal shoot elongation to reproductive meristem development at the base of current season shoots. The similarity in reproductive bud development between spurs and unpruned shoots, given the difference in active terminal growth, might suggest that developmental resources are inherently more limiting in reproductive buds on spurs.
Gibberellin4+7, Benzyladenine, and Supplemental Light Improve Postharvest Leaf and Flower Quality of Cold-stored `Stargazer' Hybrid Lilies
Authors: Ranwala Anil P. , Miller William B.
Published: January 2019

Experiments were conducted to evaluate storage temperature, storage irradiance and prestorage foliar sprays of gibberellin, cytokinin or both on postharvest quality of Oriental hybrid lilies (Lilium sp. `Stargazer'). Cold storage of puffy bud stage plants at 4, 7, or 10 °C in dark for 2 weeks induced leaf chlorosis within 4 days in a simulated consumer environment, and resulted in 60% leaf chlorosis and 40% leaf abscission by 20 days. Cold storage also reduced the duration to flower bud opening (days from the end of cold storage till the last flower bud opened), inflorescence and flower longevity, and increased flower bud abortion. Storage at 1 °C resulted in severe leaf injury and 100% bud abortion. Providing light up to 40 μmol·m-2·s-1 during cold storage at 4 °C significantly delayed leaf chlorosis and abscission and increased the duration of flower bud opening, inflorescence and flower longevity, and reduced bud abortion. Application of hormone sprays before cold storage affected leaf and flower quality. ProVide (100 mg·L-1 GA4+7) and Promalin (100 mg·L-1 each GA4+7 and benzyladenine (BA)) effectively prevented leaf chlorosis and abscission at 4 °C while ProGibb (100 mg·L-1 GA3) and ABG-3062 (100 mg·L-1 BA) did not. Accel (10 mg·L-1 GA4+7 and 100 mg·L-1 BA) showed intermediate effects on leaf chlorosis. Flower longevity was increased and bud abortion was prevented by all hormone formulations except ProGibb. The combination of light (40 μmol·m-2·s-1) and Promalin (100 mg·L-1 each GA4+7 and BA) completely prevented cold storage induced leaf chlorosis and abscission.
Phylogenetic Relationships among Selected Citrus Germplasm Accessions Revealed by Inter-simple Sequence Repeat (ISSR) Markers
Authors: Fang Deqiu , Krueger Robert R. , Roose Mikeal L.
Published: January 2019

ISSR markers were analyzed to study phylogenetic relationships among 46 Citrus L. accessions representing 35 species. A dendrogram based on the unweighted pair-group method, arithmetic average cluster analysis was constructed using a similarity matrix derived from 642 polymorphic ISSR fragments generated by 10 primers. These 46 accessions could be classified into five major groups: 1) C. indica Tan.; 2) C. maxima (Burm.) Merrill; 3) lemon [C. limon (L.) Burm.] or lime [C. aurantifolia (Christm.) Swingle] type accessions; 4) C. halimii B. C. Stone; and 5) sour orange (C. aurantium L.), mandarins and their hybrids. Group 5 was further divided into three subgroups. Although some previous work had grouped it with mandarins, C. indica appeared to be a distinct genotype or species that was not close to mandarins. C. tachibana Tan. grouped closely to mandarins. C. vulgaris Risso was not related to sour orange but was similar to accessions usually classified in the lime or lemon group. Sour orange and its hybrids, C. nippokoreana Tan., C. hanayu Hort. ex Shirai, C. sudachi Hort. ex Shirai, and C. yuko Hort. ex Tan. had close phylogenetic relationships with mandarins. Although the mandarin accessions studied were divergent in morphology, the genetic distances among them were relatively small. Relationships among these Citrus accessions revealed by ISSR markers were generally in agreement with previous taxonomic classifications.
Genetic Diversity and Geographic Differentiation in Pawpaw [Asimina triloba (L.) Dunal] Populations from Nine States as Revealed by Allozyme Analysis
Authors: Huang Hongwen , Layne Desmond R. , Riemenschneider Don E.
Published: January 2019

As a new National Clonal Germplasm Repository for Asimina species at Kentucky State University (KSU), of major concern to us is the genetic variation within our germplasm collection. The present study investigated the extent of genetic diversity for the pawpaw germplasm in our collection and the geographical pattern of genetic diversity among populations using isozyme markers. Allozyme diversity was high in Asimina triloba (L.) Dunal (Annonaceae) collected from all nine different states, as is typical for temperate woody perennial, widespread and outcrossing plant species. Averaged across populations, mean number of alleles per locus (A), percent polymorphic loci (P), effective number of alleles per locus (Ae), and expected heterozygosity (He) were 1.54, 43.5, 1.209, and 0.172, respectively. Significant deviations from Hardy-Weinberg equilibrium were found in nine populations at an average of 4.8 loci. Observed heterozygosity was higher than expected. Partitioning of genetic diversity showed that 88.2% resided within populations. The proportion of genetic diversity among populations (Gst = 0.118; FST = 0.085) was either lower than or within the range of those species with similar ecological and life-history traits. The mean genetic identity among populations was high (I = 0.988). An analysis using UPGMA clustered most populations as one major group, with the southernmost (Georgia) and the westernmost (Illinois) populations readily separated from the main group. The relationships discovered by principal component analysis (PCA) were similar to those revealed by UPGMA. In addition, PCA separated the northernmost population (New York) from the major group. Sampling strategies for future germplasm collection of A. triloba are also discussed.
The Effect of Year, Cultivar, Location, and Storage Regime on Pecan Kernel Color
Authors: Grauke L.J. , Thompson T.E. , Young E.F. , Petersen H.D.
Published: January 2019

The Munsell color system was used to study kernel color differences between four pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars (`Cheyenne', `Choctaw', `Western', and `Wichita') grown at four locations (Tulare, Calif., and Brownwood, Crystal City, and El Paso, Texas) during two seasons (1987 and 1988) and stored under different temperatures (20 to 24 °C and -5 °C). Kernel color changed over time from yellow to red hues and from lighter to darker values, but changed very little in chroma. Initial ratings of each color attribute by cultivar were positively correlated with patterns of change in that attribute over time. Kernels collected in 1987 were more yellow and had greater color saturation than kernels collected in 1988. `Cheyenne' kernels were the most yellow of the cultivars tested and `Wichita' kernels were the most red. `Cheyenne' kernels were lighter than those of any other cultivar. Kernels frozen 6 or 12 months were more red in hue than unfrozen kernels, but could not be distinguished on the basis of value (lightness). Kernels frozen 12 months had reduced chroma compared to those frozen 6 months or unfrozen. Shelled kernels of `Wichita' changed hue more in storage than kernels of other cultivars. Shelled kernels held at 20 to 24 °C became darker and developed red coloration quicker than unshelled pecans. Variation in hue and value accounted for the majority of color difference between cultivars. Changes in hue accounted for the majority of color change over time. Differences among cultivars in value (lightness) were consistent over time.
Cultivar, Fertilizer, and Irrigation Affect Vegetative Growth and Susceptibility of Chrysanthemum to Western Flower Thrips
Authors: Schuch Ursula K. , Redak Richard A. , Bethke James A.
Published: January 2019

`Fontana', `Iridon', `Pink Lady', `Splendor', `White Diamond', and `White View Time' chrysanthemum (Dendranthema × grandiflorum Ramat.) were grown for 10 weeks with N rates of 80, 160, or 240 mg·L-1 constant liquid fertilization and irrigated at sufficient (high) or deficient (low) amount. Cultivars differed in growth habit, and treatments significantly affected all variables measured. Plants fertilized with 80 mg·L-1 had lower leaf and stem dry mass, less leaf area, and were deficient in leaf N compared with plants fertilized with twice the amount of N. The highest stem dry mass was produced with 160 mg·L-1. Leaf and stem dry mass were reduced 25% for plants receiving low irrigation compared to those receiving high irrigation. In general, leaf area increased when fertilizer was raised from 80 to 160 mg·L-1 but differed by cultivar and irrigation regime when fertilizer was increased to 240 mg·L-1. Three weeks after the experiment started, electrical conductivity (EC) of runoff collected weekly from `White Diamond' plants fertilized with 240 mg·L-1 exceeded the average EC of the irrigation solution. The 240 mg·L-1 treatment also resulted in excessive EC in the growing substrate at the end of the experiment and reduced stem dry mass by 11% compared with the 160 mg·L-1 fertilizer regime. Substrate EC differed between cultivars in response to fertilizer and irrigation. Significantly more adult western flower thrips [Frankliniella occidentalis (Pergrande)], 55% and 52%, were found on the foliage of `Pink Lady' and `Fontana', respectively, than on `Iridon'. `Pink Lady' and `Fontana' had more immature thrips at the end of the experiment than `Iridon' and `White View Time'. Fewer adults and immatures were found on plants fertilized with 80 mg·L-1 than 240 mg·L-1. Fewer adults were detected in plants under high versus low irrigation, while irrigation had no effect on the number of immatures. The simultaneous use of plant varietal resistance and plant cultural growing techniques has the potential to lower thrips populations on chrysanthemum.
Measuring Water Content of Soil Substitutes with Time-domain Reflectometry (TDR)
Authors: da Silva F.F. , Wallach R. , Polak A. , Chen Y.
Published: January 2019

Optimization of irrigation and fertilization regimes in greenhouses and other controlled environments requires accurate and frequent measurements of soil-water content. Recent studies on TDR use in gravely soils and in closed-container studies have indicated a potential use of this method in horticulture. In this study, TDR calibration curves were determined for tuff (granulated volcanic ash), vermiculite, perlite and a mix of two composted agricultural wastes (grape marc, separated cow manure). Widely used as horticultural substrates, mixes of these materials were tested as well. For all soil substitutes tested, measured calibration results are well described by linear equations throughout tested values of water content that cover the working range in horticulture. Ledieu's equation, widely used in soils, describes fairly well the measured results for perlite, but underestimates those obtained for organic media, vermiculite (because of the presence of bound water) and tuff (probably due to water in occluded pores). The differences obtained between the measured calibration equations and Ledieu's equation indicate that in order to avoid an erroneous irrigation management, calibration is necessary whenever a new soil substitute is used.
Relationship between Free and Conjugated ABA Levels in Seeded and Gibberellin-treated Seedless, Maturing `Pione' Grape Berries
Authors: Kondo Satoru , Kawai Mako
Published: January 2019

Free and conjugated abscisic acid (ABA), anthocyanin and sugar concentrations were investigated in the skin of seedless `Pione' grapes (Vitis spp) treated with gibberellic acid (GA) and seeded `Pione' grapes. Seeded fruit were firmer than seedless fruit, until 53 days after full bloom (DAFB). The firmness of seeded fruit decreased dramatically between 43 and 53 DAFB. Anthocyanin concentrations increased in both types of fruit after 53 DAFB, but the concentration in seeded fruit was higher than in seedless fruit. Sugar concentration in the skin was higher in seedless than in seeded fruit prior to 53 DAFB, but at 80 DAFB sugar concentration was higher in the seeded fruit. ABA (free and conjugated forms) concentration in the skin showed a general increase towards harvest (80 DAFB). Skin ABA was higher in seeded than seedless fruit. After cis, trans-ABA (s-ABA) in the skin reached a maximum on 62 or 71 DAFB, its level decreased in both seeded and seedless fruit. The levels of trans, trans-ABA (t-ABA) and conjugated forms in both types of fruit failed to increase or increased only marginally after 62 or 71 DAFB. Free and conjugated ABA in the seed increased with DAFB until harvest. These results suggest that although maturation was promoted initially in the GA-treated seedless fruit, after 53 DAFB it was slowed relative to the seeded fruit. Enhanced maturation during the later stages of development of seeded fruit could be attributed to an increase in ABA concentration in the skin and the seed. These results also demonstrate that s-ABA is not metabolized in the skin to t-ABA and conjugated forms.
Cellulase Activity and Gene Expression in Citrus Fruit Abscission Zones during and after Ethylene Treatment
Authors: Kazokas William C. , Burns Jacqueline K.
Published: January 2019

Mature and immature `Valencia' orange [Citrus sinensis (L.) Osbeck] and immature `Valencia' orange and `Tahiti' lime (Citrus latifolia Tan.) fruit with attached pedicels were treated with 8 μL·L-1 ethylene for periods up to 24 hours. Endo-β-1,4-glucanase (cellulase) activity and gene expression were determined in fruit abscission zones during and after ethylene exposure. Cellulase activities were not detected in mature `Valencia' orange and immature `Tahiti' lime fruit abscission zones immediately following harvest and after 6 hours of ethylene treatment. After 12 hours of ethylene treatment, cellulase activity increased and was highest after 24 hours. Cellulase gene expression preceded the rise in cellulase activity and was detectable after 6 hours of ethylene treatment, but then declined after 12 hours. Following transfer to air storage, abscission zone cellulase activity in mature `Valencia' fruit remained high, whereas activity in immature `Tahiti' fruit declined. After 168 hours air storage, activity in abscission zones of mature `Valencia' fruit decreased slightly, but activity in abscission zones of immature `Tahiti' lime fruit increased to the highest level. Expression of abscission zone cellulase gene Cel-a1 in abscission zones of mature `Valencia' fruit markedly increased after transfer to air and was highest after 48 hours air storage. Cel-a1 expression returned to low levels after 168 hours of air storage, but expression of cellulase gene Cel-b1 remained at low levels throughout the air storage period. Expression of Cel-a1 and Cel-b1 declined in fruit abscission zones of immature `Valencia' and `Tahiti' lime fruit upon transfer to air. After 168 hours of air storage, expression of Cel-a1 again rose to high levels but Cel-b1 remained low. The results suggest that differences in cellulase activity and gene expression measured in mature and immature fruit abscission zones during ethylene treatment and subsequent air storage may, in part, explain the differential response of mature and immature fruit to abscission agents.
Structure of Panax quinquefolius L. (Araliaceae) Roots with Emphasis on Secretory Duct Formation
Authors: Peterson R. Larry , Varney Gregory T. , Binns Shannon
Published: January 2019

Primary and first-order lateral roots of Panax quinquefolius L. (American ginseng) were collected from plants in an experimental garden during their second year of growth and processed for light and transmission electron microscopy. Roots in primary growth had either a diarch or triarch primary xylem pattern, a pericycle, an endodermis with Casparian bands and subsequently a suberized cell wall, and a cortex of variable thickness with a suberized hypodermal layer. Both root types underwent rapid secondary growth and the primary root particularly formed a fleshy storage organ. The secondary phloem and secondary xylem had abundant parenchyma and few conducting elements. Secretory ducts differentiated in tissue derived from the pericycle and in the secondary phloem. Each schizogenous duct consisted of six to eight epithelial cells, which possessed dense, globular deposits but lacked starch. A phellogen, which produced several layers of suberized phellem, was initiated in the periphery of tissue derived from the pericycle. The results of this study clarify the anatomical localization of secretory duets in roots of this species.
Inheritance of Resistance to Anthracnose Caused by Colletotrichum coccodes in Tomato
Authors: Stommel John R. , Haynes Kathleen G.
Published: January 2019

Inheritance of resistance to tomato anthracnose caused by Colletotrichum coccodes (Wallr.) S.J. Hughes was evaluated in parental, F1, F2, and backcross populations developed from crosses between adapted resistant (88B147) and susceptible (90L24) tomato (Lycopersicon esculentum Mill.) breeding lines. Resistance was evaluated via measurement of lesion diameters in fruit collected from field-grown plants and puncture inoculated in a shaded greenhouse. Backcross and F2 populations exhibited continuous distributions suggesting multigenic control of anthracnose resistance. Anthracnose resistance was partially dominant to susceptibility. Using generation means analysis, gene action in these populations was best explained by an additive-dominance model with additive × additive epistatic effects. A broad-sense heritability (H) of 0.42 and narrow-sense heritability (h2) of 0.004 was estimated for resistance to C. coccodes. One gene or linkage group was estimated to control segregation for anthracnose resistance in the cross of 90L24 × 88B147.
Molecular Marker Analysis of Vitis vinifera `Albariño' and some Similar Grapevine Cultivars
Authors: Loureiro M. Dolores , Martínez M. Carmen , Boursiquot Jean-Michel , This Patrice
Published: January 2019

`Albariño' (Vitis vinifera L.) is an important grape cultivar in Spain, morphologically diverse but subject to much misnaming. The objectives of the present work were to correct some of the more common misnamings concerning `Albariño' and to evaluate the genetic variability within this cultivar by analyzing DNA polymorphisms using randomly amplified polymorphic DNA (RAPD) markers and microsatellite techniques. Several accessions of `Albariño' (16 accessions from Misión Biológica de Galicia, one accession from El Encin, one accession from Rancho de la Merced), related cultivars (`Alvarinho', `Caíño blanco', `Cainho branco', `Loureiro'), and cultivars presumably identical to misnomers (`Savagnin blanc' and `Gewürztraminer') were analyzed using 20 RAPD markers and six microsatellite loci. Both techniques revealed polymorphism among `Albariño', `Caíño blanco', `Albariño' from Rancho de la Merced and `Loureiro'. No polymorphism was detected among the 16 `Albariño' accessions from Galicia, the `Albariño' accession from El Encin and `Alvarinho', nor among the `Albariño' accession from Rancho de la Merced, `Savagnin blanc' and `Gewürztraminer', nor between `Caíño blanco' and `Cainho branco'. These results enabled us to clarify the main misnomers concerning these cultivars. The absence of polymorphism among the true `Albariño' accessions did not allow the detection of any clonal variation. The suitability of both techniques for defining the cultivar level for grapevine is discussed.
Mapping Genes for Specific and Adult Plant Resistance to Rust and Abaxial Leaf Pubescence and their Genetic Relationships Using Randomly Amplified Polymorphic DNA (RAPD) Markers in Common Bean
Authors: Jung Geunhwa , Coyne Dermot P. , Bokosi James , Steadman James R. , Nienhuis James
Published: January 2019

Dry bean (Phaseolus vulgaris L.) production is limited by bean rust [Uromyces appendiculatus (Pers.) Unger var. appendiculatus]. An effective control strategy for this disease is to breed cultivars with durable resistance. Information on the inheritance, genetic relationships, and mapping of genes with molecular markers for specific resistance (SR), adult plant resistance (APR), and abaxial leaf pubescence (ALP) is needed to pyramid the desired genes for durable resistance. ALP was found to be associated previously with APR in Andean germplasm. The objective here was to identify and map RAPD markers for the genes controlling SR, APR, and ALP and to examine their relationships. Five rust pathotypes were inoculated on the unifoliate leaves of 68 recombinant inbred (RI) lines derived from `PC-50' (presence of SR, APR, and ALP) × XAN-159 (absence of SR, APR, and ALP). SR was determined by a single major gene (Ur-9) to the five rust pathotypes with no detection of recombinants. The fourth trifoliolate leaves were inoculated with one pathotype (A88T1-4b). A single major gene Ur-12 controlled APR to that pathotype. The Ur-9 gene (SR) was independent of and epistatic to the Ur-12 gene (APR). Because of the low number of APR lines in the RI population resulting from the elimination of RI lines with SR, an F2 population was developed from a cross of two homozygous RI lines selected for unifoliate susceptibility to pathotype A88T1-4b and for resistance and susceptibility of the fourth trifoliolate leaves to tag RAPD markers linked to the Ur-12 gene (APR). The single major gene Pu-a determinated ALP and was not linked to Ur-9 (SR) and Ur-12 (ALP). The gene Ur-9 (SR) was linked to RAPD marker J13-1100 at 5 cM and was not assigned to any linkage group or other markers. The gene Pu-a (ALP) was mapped at 20.2 cM from 116.500 and 3.9 cM from marker G3.1150 in linkage group 3. The Ur-12 gene (APR) was mapped at 34.6 cM from marker O13.1350 in linkage group 4b. This is the first report of mapping a gene for APR in common bean.