bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Similarities among Wine Grape Cultivars Revealed by Restriction Fragment-length Polymorphism (RFLP) Analysis
Authors: Bowers John E. , Meredith Carole P.
Published: January 2019

RFLP data were used to assess genetic similarity among 33 Vitis vinifera L. cultivars and one interspecific cultivar. A similarity matrix was constructed on the basis of the presence or absence of 49 bands generated by eight RFLP probes and cluster analysis was performed. The mean similarity index for all pairwise comparisons was 0.696 and ranged from 0.444 between `St. Emilion' and the interspecific hybrid `Salvador' to 0.952 between `Chenin blanc' and `Semillon'. Mean similarity among all V. vinifera cultivars was 0.705. Several groupings of similar cultivars are consistent with historical reports and presumed geographic origins: `Chardonnay' and `Melon', `Colombard' and `Folle blanche', `Gewürztraminer' and `Trousseau', `Cabernet franc' and `Cabernet Sauvignon', `Mission' and `Palomino'. The similarity between `Mission' and `Palomino' is the first genetic evidence to support the putative Spanish origin of `Mission'. Some groupings are unexpected (`Sauvignon blanc' and `Gewürztraminer', `Chenin blanc' and `Semillon') because the cultivars are not thought to have originated in the same regions. While some relationships suggested by this study may be artifacts of RFLP analysis or of the statistical method, they raise questions for further genetic inquiry into the origins of grape cultivars.
Sensitivity of Seedling Radicles to Chilling and Heat-shock-induced Chilling Tolerance
Authors: Rab Abdur , Saltveit Mikal E.
Published: January 2019

The sensitivity of corn, cucumber, mung bean, and tomato seedling radicles to chilling (i.e., inhibition of subsequent elongation at 25 C after chilling at 2.5 C) was greater for radicles 5 to 7 mm long than for radicles 1 mm long. In contrast, radicles of germinating okra seeds had a similar level of chilling inhibition (i.e., 70% to 90%) at lengths of 1 to 7 mm. For seeds with 1-mm-long radicles, subsequent radicle elongation for cucumber was inhibited only 2% by 72 hours of chilling at 2.5 C, while it was inhibited about 20% for corn, mung bean, and tomato. For seeds with 5- to 7-mm-long radicles, chilling inhibition was 50% to 70% for corn, mung bean, and tomato and 80% to 90% for cucumber and okra. The degree of chilling sensitivity varied among species in relation to time required to elicit a significant response and the magnitude of the elicited response. The development of lateral roots decreased with prolonged chilling in all species. Heat shock (i.e., 4 to 10 minutes at 45 C) induced chilling tolerance in all species except okra. In okra, neither increasing the heat-shock temperature nor decreasing the severity of chilling (i.e., temperature and duration of exposure) significantly reduced chilling injury.
Level of Heterozygosity and Mode of Inheritance of Variable Number of Tandem Repeat Loci in Avocado
Authors: Mhameed Samir , Sharon Dror , Hillel Jossi , Lahav Emanuel , Kaufman Daniel , Lavi Uri
Published: January 2019

To estimate heterozygosity level in the avocado (Persea americana Mill.) genome, two types of variable number of tandem repeat (VNTR) markers were used. Multilocus DNA fingerprints (DFPs) were analyzed on avocado progeny resulting from either crosses or selfing of cultivars. In five crosses, heterozygosity was 100%, while in two self-pollinated families, heterozygosity was 90% and 94%. Single locus, simple sequence repeat (SSR) DNA markers were analyzed by typing 59 loci on five avocado cultivars. Average heterozygosity varied from 0.50 to 0.66, while gene diversity varied from 0.42 to 0.66. Heterozygosity varied from 38% to 70%. The percentage of fragments that exhibited Mendelian inheritance was 62.5% to 85% (P < 0.05) for the DFP fragments and 85% for the SSR alleles.
Randomly Amplified Polymorphic DNA (RAPD) Variation among and within Artichoke (Cynara scolymus L.) Cultivars and Breeding Populations
Authors: Tivang Jan , Skroch Paul W. , Nienhuis James , De Vos Neal
Published: January 2019

The magnitude of genetic differences among and heterogeneity within globe artichoke cultivars is unknown. Variation among individual heads (capitula) from three artichoke cultivars and two breeding populations were evaluated using RAPD markers. One vegetatively propagated cultivar (`Green Globe'), two seed-propagated cultivars (`Imperial Star' and `Big Heart') and two breeding populations were examined. Two to thirteen polymorphic bands were observed for 27 RAPD primers, which resulted in 178 scored bands. Variation was found within and among all cultivars, and breeding populations indicating that all five groups represent heterogeneous populations with respect to RAPD markers. The genetic relationships among individual genotypes were estimated using the ratio of discordant bands to total bands scored. Multidimensional scaling of the relationship matrix showed five independent clusters corresponding to the three cultivars and two breeding populations. The integrity of the five clusters was confirmed using pooled chi-squares for fragment homogeneity. Average gene diversity (Hs) was calculated for each population sample, and a one-way analysis of variance showed significant differences among populations. `Big Heart' had an Hs value equivalent to the two breeding populations, while clonally propagated `Green Globe' and seed propagated `Imperial Star' had the lowest Hs values. The RAPD heterogeneity observed within clonally propagated `Green Globe' is consistent with phenotypic variability observed for this cultivar. Overall, the results demonstrate the utility of the RAPD technique for evaluating genetic relationships and contrasting levels of genetic diversity among populations of artichoke genotypes.
Variation in Calcium Concentration among Sixty S1 Families and Four Cultivars of Snap Bean (Phaseolus vulgaris L.)
Authors: Quintana Juan M. , Harrison Helen C. , Nienhuis James , Palta Jiwan P. , Grusak Michael A.
Published: January 2019

To assess nutritional potential, pod yield, and Ca concentration of pods and foliage were determined for a snap bean population, which included sixty S1 families plus four commercial varieties. The experimental design was an 8 × 8 double lattice, repeated at two locations (Arlington and Hancock, Wis.). Snap beans were planted in June 1993 and machine harvested in August 1993. Calcium analyses were made using an atomic absorption spectrophotometer. Significant differences were detected in pod Ca concentration and yield among the S1 families. Pod size and Ca concentration were inversely correlated (R2 = 0.88). Distinct differences between the locations were not observed, and higher Ca genotypes remained high regardless of location or pod size. Low correlation (R2 = 0.21) between pod and leaf Ca concentration was found. Pods of certain genotypes appeared to have the ability to import Ca more efficiently than others, but this factor was not related to yield.
Movement Patterns of Carbon from Source to Sink in Cranberry
Authors: Roper Teryl R. , Klueh John S.
Published: January 2019

The source of photosynthate for developing cranberry (Vaccinium macrocarpon Ait.) fruit can be partitioned spatially among new growth acropetal to fruit, 1-year-old leaves basipetal to fruit, and adjacent uprights along the same runner. Cranberry uprights were labeled with 14CO2 in an open system with constant activity during flowering or fruit development. When new growth acropetal to fruit was labeled, substantial activity was found in flowers or fruit. Little activity was found in basipetal tissues. When 1-year-old basipetal leaves were labeled, most of the activity remained in the labeled leaves, with some activity in flowers or fruit. Almost no labeled C moved into acropetal tissues. When new growth of adjacent nonfruiting uprights on the same runner were labeled, almost no activity moved into the fruiting upright. These data confirm that new growth acropetal to developing flowers and fruit is the primary source of photosynthate for fruit development. Furthermore, they show that during the short time studied in our experiment, almost no C moved from one upright to another.
The Bases of Productivity in Apple Production Systems: The Role of Light Interception by Different Shoot Types
Authors: Wünsche Jens N. , Lakso Alan N. , Robinson Terence L , Lenz Fritz , Denning Steven S.
Published: January 2019

Although apple (Malus domestica Borkh.) system yield differences are generally related to whole-canopy light interception, this study tested the hypothesis that these orchard yields are related primarily to total light intercepted by the spur canopy. Seasonal leaf area development of different shoot types, exposed bourse shoot leaf net photosynthesis, fruit growth, whole canopy light interception (by image analysis of fisheye photographs) and relative light interception by different shoot types (by a laser assisted canopy scanning device) were estimated within four 14-year-old `Empire' apple production systems (slender spindle/M.9, central leader/M.7, central leader/M.9/MM.111 and Y-trellis/M.26). The final LAI values were CL/M.7 = 1.8, CL/9/111 = 2.3, SS/M.9 = 2.6 and Y/M.26 = 3.6. Exposed leaf net photosynthesis showed few differences and was not dependent upon the production system. Yields of the pyramidal shaped tree forms were 40 to 42 t·ha-1 while Y-trellis produced 59 t·ha-1, with similar fruit sizes. Again, yields were primarily related to the percentage of light intercepted by the whole canopy, 48% to 53% for conic forms versus 62% for the Y-trellis system. Laser analyses showed that the Y-trellis system intercepted about 20% to 30% more light with the spur canopy than the conic tree forms, supporting the hypothesis. Yields were better correlated with spur canopy LAI and spur canopy light interception than with extension shoot canopy LAI and light interception.
Effect of Chilling on the Gravitropic Response of `Poinsett 76' Cucumber (Cucumis sativus L.) Radicles
Authors: Rab Abdur , Saltveit Mikal E.
Published: January 2019

Germinating `Poinsett 76' cucumber (Cucumis sativus) seeds are chilling sensitive, and subsequent radicle elongation is inhibited by exposure to nonfreezing temperatures below 10 °C. Reorienting germinated seeds with 5-mm-long radicles from a vertical to a horizontal position induced gravitropic curvature within 2 hours at 10 to 25 °C without significantly affecting the rate of radicle elongation. However, neither elongation nor curvature occurred in similar seeds held at 2.5 or 5 °C. Chilling seeds with 5-mm-long radicles at 2.5 °C for 18 hours significantly reduced the subsequent rate of radicle elongation at 25 °C by 47% compared with nonchilled control, while gravitropic curvature was reduced by only 34%. After 36 hours of recovery at 25 °C, the difference was even more pronounced; elongation was reduced by 26% while curvature was reduced by only 6%. Clearly, gravitropic curvature was less chilling sensitive than radicle elongation, despite the fact that differential elongation of cells in the radicle are needed to produce curvature. Exposing seeds with 5-mm-long radicles to a heat shock of 45 °C for 4 to 10 minutes significantly diminished the chilling-induced reduction in radicle elongation and gravitropic curvature.
Cold Acclimation and Alterations in Dehydrin-like and Bark Storage Proteins in the Leaves of Sibling Deciduous and Evergreen Peach
Authors: Arora Rajeev , Wisniewski Michael , Rowland Lisa J.
Published: January 2019

Seasonal changes in cold tolerance and proteins were studied in the leaves of sibling deciduous and evergreen peach [Prunus persica (L.) Batsch]. Freezing tolerance [defined as the subzero temperature at which 50% injury occurred (LT50)] was assessed using electrolyte leakage. Proteins were separated by sodium dodecyl sulfate polyacrylamide-gel electrophoresis. Electroblots were probed with anti-dehydrin and anti-19-kD peach bark storage protein (BSP) antibodies. Leaf LT50 decreased successively from -5.8 °C on 18 Aug. to -10.3 °C in the evergreen genotype and from -7.0 °C to -15.0 °C in the deciduous genotype by 14 Oct. Protein profiles and immunoblots indicated the accumulation of a 60- and 30-kD protein during cold acclimation in the leaves of deciduous trees; however, levels of these proteins did not change significantly in the evergreen trees. Immunoblots indicate that the 60-kD protein is a dehydrin-like protein. Gel-electrophoresis and immunoblots also indicated that the 19-kD BSP progressively disappeared from summer through fall in leaves of deciduous peach but accumulated to a high level in bark tissues. A similar inverse relationship was not evident in evergreen peach.
Pecan Scab Fungus Lacks Substrate Specificity for Early Infection Stages
Authors: Yates I.E. , Cason K.M.T. , Sparks Darrell
Published: January 2019

Leaves and callus of pecan [Carya illinoinensis (Wangenh.) K. Koch], and glass, dialysis membrane, and agar were examined for capacity to support two of the earliest infection stages—conidium (spore) germination and appressorium formation—of Cladosporium caryigenum (Ellis & Langl.) Gottwald, the fungus causing pecan scab. Light and temperature effects on formation of germ tubes and appressoria were examined for conidia suspended in distilled-deionized water. Conidia formed germ tubes on all substrates and in distilled-deionized water; hence, conidia possessed endogenous materials required for germination and are independent of specific topographic or chemical stimuli. All substrates, except 2% water agar and water, sustained appressoria development, thus implicating regulation by surface hardness. More appressoria formed on leaf discs than on other substrates. Additionally, conidia formed appressoria with short germ tubes when near a leaf structural feature, such as stomatal guard cells. Thus, the pecan scab fungal isolate used in these experiments appeared to lack substrate specificity for forming germ tubes, but not appressoria, during the prepenetration stages of development. Conidium germination was maximized at about 25 °C and germination did not respond to light.
Carbon Balance as a Physiological Basis for the Interactions of European Red Mite and Crop Load on `Starkrimson Delicious' Apple Trees
Authors: Francesconi A.H.D. , Lakso A.N. , Nyrop J.P. , Barnard J. , Denning S.S.
Published: January 2019

The hypothesis that carbon balance is the basis for differences in responses by lightly and normally cropped apple trees to European red mite (ERM) [Panonychus ulmi (Koch)] damage was tested. Mature `Starkrimson Delicious' (Malus domestica Borkh.)/M.26 apple trees were hand-thinned to light (125 fruit/tree, about 20 t/ha) or normal (300 fruit/tree, about 40 t/ha) target crop levels and infested with low [<100 cumulative mite-days (CMD)], medium (400 to 1000 CMD) or high (>1000 CMD) target levels of ERM. A range of crop loads and CMD was obtained. Mite population density, fruit growth, leaf and whole-canopy net CO2 exchange rates (NCER) were measured throughout the growing season of 1994. Leaf area and vegetative growth per tree were also measured. Yield and final mean fruit size were determined at harvest. Return bloom and fruiting were determined the following year. Total shoot length per tree was not affected by crop load or mite damage. ERM reduced leaf and whole-canopy NCER. Normally cropped trees showed fruit weight reduction earlier and more severely than lightly cropped trees with high mite injury. Variation in final fruit weight, return bloom and return fruiting was much better related to whole-canopy NCER per fruit than to CMD.
Detecting Cross-incompatibility of Three North American Apricot Cultivars and Establishing the First Incompatibility Group in Apricot
Authors: Egea J. , Burgos L.
Published: January 2019

Laboratory and orchard tests have shown that the apricot (Prunus armeniaca L.) cultivars `Hargrand', `Goldrich', and `Lambertin-1' are cross-incompatible. All three cultivars are from North American breeding programs and have `Perfection' as a common ancestor. In orchard tests, compatible pollinations resulted in 19% to 74% fruit set, while incompatible pollinations resulted in <2% fruit set. Microscopic examination showed that, in incompatible pollinations, pollen tube growth was arrested in the style, most frequently in its third quarter, and that the ovary was never reached. It is proposed that self-incompatibility in apricot is of the gametophytic type, controlled by one S-locus with multiple alleles, and that these three cultivars are S1S2.
Genetic Diversity in Peach (Prunus persica L. Batch) Revealed by Randomly Amplified Polymorphic DNA (RAPD) Markers and Compared to Inbreeding Coefficients
Authors: Warburton Marilyn L. , Bliss Fredrick A.
Published: January 2019

Previous studies of peach germplasm using pedigree information and isozyme polymorphism data have shown limited diversity in the U.S. gene pool. To further investigate the genetic diversity among peach cultivars grown in different regions of the United States, 94 RAPD markers were used to estimate the genetic distances among 136 cultivars. Of the 12 clusters formed in a dendrogram, the 90 U.S. cultivars and breeding lines and most of those from Europe and Latin America grouped to only three clusters, while the 23 peach entries from India, Pakistan, Russia, Okinawa, and China, as well as the almond cultivar used as an outgroup, were distributed among the other nine clusters. Therefore, the genetic diversity within temperate U.S. peach germplasm is quite limited, and to expand the variability, additional germplasm should be obtained, especially from Asia. Comparison of genetic similarity based on inbreeding coefficients with similarity coefficients based on the RAPD data produced a correlation of 0.395, which is comparable to values in similar investigations in other crops. Thus, similar conclusions can be drawn from these two sources of information. RAPD data are useful particularly when pedigree information is incomplete, there has been substantial selection within breeding populations, and a high proportion of alleles are identical in state but not by descent.
Physiological, Biochemical, and Molecular Changes in Pelargonium Cuttings Subjected to Short-term Storage Conditions
Authors: Arteca Richard N. , Arteca Jeannette M. , Wang Tzann-Wei , Schlagnhaufer Carl D.
Published: January 2019

The purpose of this study was to evaluate physiological, biochemical, and molecular changes that occur in unrooted Pelargonium ×hortorum cuttings during storage. Pelargonium cuttings of `Sincerity' (good shipper), `Wendy Ann' (moderate shipper) and `Snowmass' (poor shipper) were stored at 25 °C and evaluated over a 5-day period. Following removal from storage, cuttings of all cultivars exhibited steady and significant decline in photosynthesis, respiration, carbohydrate, starch, and protein over time. However, no significant differences were observed among cultivars for all of these parameters. Ethylene levels produced by `Sincerity' and `Wendy Ann' began to increase 3 days following storage; whereas, `Snowmass' showed an increase after 1 day, reaching a peak at 3 days, and then declined. When unrooted cuttings of `Snowmass' were stored for 5 days at temperatures ranging from 4 to 25 °C, it was observed that those stored at 4 °C had a significantly higher visual rating, chlorophyll content, and root and shoot weight than at higher temperatures tested. As temperature increased from 10 to 25 °C, quality of cuttings declined. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in `Snowmass' cuttings stored at 4 and 25 °C. Correlations between ethylene and ACC levels with gene expression were observed. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC).
Alteration of Seedstalk Development, Seed Yield, and Seed Quality in Carrot by Varying Temperature during Seed Growth and Development
Authors: Elballa Mustafa M.A. , Cantliffe D.J.
Published: January 2019

The effect of temperature on seedstalk development, seed yield and quality in carrot (Daucus carota L.) was investigated in growth chambers at constant day/night temperatures of 33/28, 28/23, 25/20, 23/18, 20/15, and 17/12 °C. Days to flowering, seedstalk height, number of umbels, and seed yield decreased linearly with increasing temperature from 17/12 to 33/28 °C. Continuous high temperature (33/28 °C) had a detrimental effect on germination as measured by a standard germination test and an accelerated aging test. Optimum germination of the progeny occurred at 20/15 °C; however, germination rate was faster when seeds matured at 23/18 °C. Seeds that developed at 33/28 °C produced seedlings with the lowest vigor, while those which developed at 20/15 °C produced seedlings with the highest vigor. Brief exposure of plants to 33/28 °C during anthesis or early seed development was as detrimental to seed yield as continuous exposure to 33/28 °C. Exposure to high temperature (33/28 °C) during late seed development had less effect on seed yield, and seed quality was improved. Progeny vigor was reduced greatly by seed development at continuous high temperature (33/28 °C), but was unaffected by brief exposure to 33/28 °C at anthesis, early, or late in seed development. These results suggest that high (33/28 °C) day/night temperatures during pollination, fertilization, or early stages of seed development can greatly reduce carrot seed yield and seed quality.
Ethylene Affects Postproduction Quality of Easter Cactus
Authors: Han Susan S. , Boyle Thomas H.
Published: January 2019

Experiments were performed to determine the effects of ethylene (C2H4) on the postproduction quality of Easter cactus [Hatiora gaertneri (Reg.) Barthlott and H. ×graeseri (Werderm.) Barthlott]. Significant differences in percent bud abscission were observed among cultivars when plants were exposed to 0.4 or 1.0 μL·L-1 C2H4 for 48 hours. Fewer buds abscised on `Andre' and `Red Pride' than on `Evita', `Rood', and `Thor-Anne'. Stage of floral development at the time of C2H4 exposure affected the pattern and severity of bud abscission for `Crimson Giant'. Percent bud abscission was greater for plants treated with 0.5 μL·L-1 C2H4 in the small-bud stage (largest buds 7 to 13 days from anthesis) than for plants treated in the medium-bud stage (largest buds 3 to 4 days from anthesis) or large-bud stage (largest buds 1 day from anthesis). Application of 1 or 2 mm silver thiosulfate (STS) was as effective as 3 mm STS in reducing bud abscission on plants exposed to 0.5 μL·L-1 C2H4 in the small-bud stage. Treatment with 2 mm STS before C2H4 exposure increased the display life (number of days from anthesis of the first flower to senescence of the last flower) of `Andre' in all three developmental stages, but increased the display life of `Crimson Giant' only in the small bud stage. These results demonstrate that the response of Easter cactus to C2H4 is affected by cultivar, C2H4 concentration, stage of floral development at the time of C2H4 exposure, and STS pretreatment.
Partitioning of Allozyme Diversity in Wild Populations of Malus sieversii L. and Implications for Germplasm Collection
Authors: Lamboy Warren F. , Yu Jing , Forsline Phil L. , Weeden Norman F.
Published: January 2019

One of the primary progenitors of the cultivated apple is Malus sieversii L., a species native to the forested regions of central Asia. Despite the horticultural importance of M. sieversii, little is known about genetic variation in this species. In this study, allozyme diversity at 18 loci was determined for 259 seedlings belonging to 31 sib families, each consisting of the set of offspring from a different open-pollinated maternal (seed) parent. Maternal parents belonged to 14 populations from four geographic regions. Genetic diversity statistics were computed from the resulting allele and phenotype frequencies. Cluster analysis of sib families showed that there was some grouping based on geographic region, but 16 of the sib families were most closely related to sib families from other regions. Analysis of molecular variance (AMOVA) indicated that 85% of the enzyme variability was due to differences among sib families within populations and 15% was due to differences among regions. No variability could be assigned to differences among populations within regions. In addition, no alleles were found that were fixed in a region and unique to that region. These results suggest that plants belonging to M. sieversii effectively form a panmictic population. Consequently, a thorough sampling of a few large populations will efficiently capture most of the genetic diversity present in wild M. sieversii.
Evaluating Twenty-eight Strains of `Delicious' Apple in Michigan
Authors: Dennis F.G. , Masabni J.G. , Ketchie D.O.
Published: January 2019

A cooperative experiment begun in 1980 was designed to evaluate the productivity and other characteristics of 16 spur and 12 standard strains of `Delicious' apple on two rootstocks (M.7 EMLA and MM.111 EMLA). All trees were propagated at one nursery, and plantings were established in Michigan, Washington, Oregon, Idaho, Indiana, and British Columbia. In Michigan, trees of standard strains were consistently larger than trees of spur strains 8 years after planting. Early yields were greater on M.7 EMLA than on MM.111 EMLA, but trees were more subject to leaning under heavy crops on M.7 EMLA. In general, spur-type strains yielded more fruit per unit trunk cross-sectional area than standard strains. Yield was more closely associated with fruit-setting ability than with flower density, and fruit size declined as fruit set increased. Length/diameter ratios and biennial bearing indices also differed significantly among strains.
Isozyme, Randomly Amplified Polymorphic DNA (RAPD), and Restriction Fragment-length Polymorphism (RFLP) Markers Used to Deduce a Putative Parent for the `Braeburn' Apple
Authors: Gardiner S.E. , Bassett H.C.M. , Madie C. , Noiton D.A.M.
Published: January 2019

Information about a rare allele of phosphoglucomutase (PGM) that is shared by `Braeburn' and 16% of cultivars in the New Zealand Cultivar Collection was combined with historical information about cultivar distribution to select a set of 15 cultivars for a more detailed genetic analysis of their relatedness to the key New Zealand apple (Malus domestica Borkh.) `Braeburn'. DNA from all 16 cultivars was examined by RFLP analysis using 41 probe-enzyme combinations and also by RAPD analysis with 39 selected primers. The RFLP and RAPD data excluded a proposal that `Lady Hamilton' and `Braeburn' are genetically identical. All cultivars except `Lady Hamilton' were excluded as potential parents for `Braeburn' based on incompatible RFLP banding. Assessment of genetic distances between `Braeburn' and the other 15 cultivars from RFLP and RAPD data demonstrated that `Lady Hamilton' was more closely related to `Braeburn' than all others. We conclude that there is a high likelihood that `Lady Hamilton' is one of the parents of `Braeburn'.
Irradiation-induced Changes in Tomato Fruit and Pericarp Firmness, Electrolyte Efflux, and Cell Wall Enzyme Activity as Influenced by Ripening Stage
Authors: Assi Najib El , Huber Donald J. , Brecht Jeffery K.
Published: January 2019

Mature green and pink tomato (Lycopersicon esculentum Mill.) fruit were subjected to ionizing irradiation in the range of 0.7 to 2.2 kGy from gamma-or X-ray sources. Firmness of whole fruit and pericarp tissue, pericarp electrolyte leakage, and pericarp cell wall hydrolase activities were measured following irradiation and during postirradiation ripening at 20 °C. Irradiation-induced softening was evident in mature-green and pink fruit within hours following irradiation, and differences between irradiated and control fruit persisted throughout postirradiation storage. Trends of firmness loss were much more consistent and showed much greater dose dependency in pericarp tissue than whole fruit. Irradiation enhanced electrolyte efflux in fruit of both maturity classes. Fruit irradiated at the mature-green stage softened during postirradiation storage but exhibited an apparently irreversible suppression in polygalacturonase activity, with levels remaining <10% of those of nonirradiated fruit. Polygalacturonase activity was less strongly affected in irradiated pink fruit than in mature-green fruit, but activity remained reduced relative to the controls. Pectinmethylesterase and β-galactosidase activities were significantly enhanced in irradiated fruit of both ripening stages in the early period following irradiation, but reductions were noted after prolonged storage.
Anthocyanin Accumulation during Potato Tuber Development
Authors: Hung Chen-Yi , Murray John R. , Ohmann Sarah M. , Tong Cindy B.S.
Published: January 2019

The color of red potato tubers is due to an accumulation of anthocyanins in periderm and peripheral cortex tissues. The objective of this study was to characterize changes in anthocyanin content and tuber surface color during tuber development. Using the red tuber-producing potato (Solanum tuberosum L.) cultivar Norland, we observed that chroma (intensity of redness) and anthocyanin content per unit of surface area of greenhouse-grown tubers decreased as tuber weight increased. There was no increase in hue (tint) during the same developmental periods. Using high-performance liquid chromatography (HPLC), we determined that pelargonidin and peonidin are the major anthocyanidins (aglycones of anthocyanins) in the tuber periderm. Northern blot analyses indicated that steady-state mRNA levels of dihydroflavonol reductase (DFR), an anthocyanin biosynthetic enzyme, continued throughout tuber development. These results suggest that anthocyanins are synthesized throughout tuber development, and that cell division and/or enlargement contribute to a decline in chroma and anthocyanin concentration.
Aluminum and Phosphorus Interactions in Mycorrhizal and Nonmycorrhizal Highbush Blueberry Plantlets
Authors: Yang Wei Qiang , Goulart Barbara L.
Published: January 2019

Aluminum (Al) and phosphorus (P) interactions were investigated in mycorrhizal (M) and nonmycorrhizal (NM) highbush blueberry (Vaccinium corymbosum L.) plantlets in a factorial experiment. The toxic effects of Al on highbush blueberry were characterized by decreased shoot, root, and total plant dry mass. Many of the negative effects of Al on plant root, shoot, and total dry matter production were reversed by foliar P and N application, indicating P or N uptake were limited by high Al concentration. However, Al-mediated growth reduction in P-stressed plants indicated that the restriction of P uptake by high Al may not have been the only mechanism for Al toxicity in this experiment. Root Al and P concentration were negatively correlated in NM but not M plantlets, suggesting mycorrhizal infection may alter P uptake processes. Al uptake was also affected by mycorrhizal infection, with more Al accumulating in M plantlet roots and leaves. Correlations among foliar ion concentrations were also affected by mycorrhizal fungal infection.
Leaf Development, Dry Matter Accumulation, and Distribution within Branches of Alternate-bearing `Kerman' Pistachio Trees
Authors: Nzima Muntubani D.S. , Martin George C. , Nishijima Chic
Published: January 2019

We investigated the development of leaf area (LA) and the distribution of dry matter within branches of 25-year-old, alternate-bearing `Kerman' pistachio (Pistacia vera L.) trees that were in their natural “on” (heavy) or “off” (light) bearing cycles to determine the immediate and delayed effects of fruiting on shoot growth. Compared to “off” trees, individual leaves of “on” trees were greater in number and expanded twice as fast during the first 30 days after full bloom (FB) (FB + 30). Mature, fully expanded leaves of “on” trees were smaller (124.1±3.26 cm2) than those from “off” tree (163.3±3.40 cm2), indicating delayed demands of fruiting on initial leaf growth. Total LA per current shoot was greater in “on” than “off” trees because shoots of “on” trees averaged eight leaves, compared with six for “off” trees. More inflorescence buds per shoot (seven vs. three buds) abscised from “on” than from “off” trees. About 60% of the young developing nuts had abscised by FB + 30 when they weighed <250 mg each and another 25% abscised between FB + 30 and FB + 60 when individual nuts weighed ≈400 mg. The average total dry mass (DM) of individual branches of “on” trees increased 1322% (5·9 to 83·9 g) compared to 598% (4·2 to 29·3 g) in “off” trees. Besides nuts, leaves accumulated the greatest amount of dry matter within individual branches followed in decreasing order by current wood, 1-year-old wood, and inflorescence buds. DMs of individual leaves of “on” trees averaged between 15% and 48% greater than leaves of “off” trees. “Off” trees invested 4.6 g of dry matter into individual 1-year-old wood and 2.1 g into current wood. “On” trees, however, invested 1.3 g of dry matter into 1-year-old wood and 4.3 g of dry matter into current wood. One-year-old wood was an important major source of carbohydrates for developing leaves, current wood, rachises, and nuts. The immediate demands of fruiting on individual components of a branch were measured as losses in DMs. Individual leaves, current wood, 1-year wood, and rachises lost 1.1%, 0.3%, 1.1%, and 1.0%, respectively, of the average total DMs of individual branches of “on” trees. This loss was equivalent to 5.7%, 5.9%, 26.7%, and 16.4%, respectively, of the seasonal average peak DMs of the respective individual components of the branch.
Randomly Amplified Polymorphic DNA- (RAPD-) based Genetic Linkage Map of Blueberry Derived from an Interspecific Cross between Diploid Vaccinium darrowi and Tetraploid V. corymbosum
Authors: Qu Luping , Hancock James F.
Published: January 2019

A tetraploid blueberry population resulting from a cross of US 75 {a tetraploid hybrid of Fla 4B [a selection of Vaccinium darrowi Camp (2n = 2x = 24) × `Bluecrop' [(V. corymbosum L. (2n = 4x = 48)]} × `Bluetta' (4x) was used to generate a genetic linkage map of US 75 by randomly amplified polymorphic DNA (RAPD) analysis. One hundred and forty markers unique for Fla 4B that segregated 1:1 in the population were mapped into 29 linkage groups that cover a total genetic distance of 1288.2 cM, with a range of 1.6 to 33.9 cM between adjacent markers. The map is essentially of V. darrowi because US 75 was produced via a 2n gamete from Fla 4B and only unique markers for Fla 4B were used. Therefore, all the chromosomes of V. darrowi could be represented in the map.
Identifying Blueberry Cultivars and Evaluating Their Genetic Relationships Using Randomly Amplified Polymorphic DNA (RAPD) and Simple Sequence Repeat- (SSR-) anchored Primers
Authors: Levi A. , Rowland L.J.
Published: January 2019

Fifteen highbush (or highbush hybrid) blueberry cultivars (Vaccinium corymbosum Linnaeus), two rabbiteye blueberry cultivars (V. ashei Reade), and one southern lowbush (V. darrowi Camp) selection from the wild were examined using seventeen 10-base RAPD and seven 15- to 18-base SSR-anchored primers (primers comprised of SSR motifs) in polymerase chain reactions (PCRs). Fifteen RAPD and three SSR markers resulting from these reactions were chosen to construct a DNA fingerprinting table to distinguish among the genotypes included in this study. Similarity values were calculated based on 132 RAPD and 51 SSR bands, and a dendrogram was constructed based on the similarity matrix. The V. ashei cultivars and V. darrowi selection grouped out separately from the V. corymbosum cultivars as expected. However, estimates of relative genetic similarity between genotypes within the V. corymbosum group did not agree well with known pedigree data and, thus, indicated that RAPD and SSR data did not accurately assess the genetic relationships of cultivars within this species.
Genetic Linkage of Randomly Amplified Polymorphic DNA (RAPD) Markers in Sweetpotato
Authors: Thompson Paul. G. , Hong Liang L. , Ukoskit Kittipat , Zhu Zhiqiang
Published: January 2019

RAPD marker analyses were completed on parents and progeny of two sweetpotato [Ipomoea batatas (L.) Lam.] crosses to determine the feasibility of genetic linkage map construction. A total of 100 primers was tested and 96 produced amplified genomic DNA fragments. The average number of polymorphisms per primer was 0.69. A total of 134 polyphorphic markers was observed and 74 (60%) segregated 1 band present : 1 band absent as needed for use in genetic linkage mapping of polyploids. The 60% of RAPD markers that segregated 1:1 shows that genetic linkage mapping of the hexaploid sweetpotato by RAPD marker analysis is feasible. Linkage was determined for all markers that segregated 1:1 and five pairs of linked markers were found. These were the first linked molecular markers found in sweetpotato and they show that construction of a genetic linkage map is feasible. A genetic linkage map will be a valuable tool to assist in genetic improvements.
Proline Accumulation and Methylation to Proline Betaine in Citrus: Implications for Genetic Engineering of Stress Resistance
Authors: Nolte Kurt D. , Hanson Andrew D. , Gage Douglas A.
Published: January 2019

Proline and various betaines can function as osmoprotectants and cryoprotectants when accumulated in the cytoplasm of cells. Genetic engineering can raise levels of these compounds and thereby improve stress resistance; Citrus species are potential candidates for this. Before attempting such engineering, it is necessary to characterize the natural osmoprotectants of Citrus and related genera. We therefore surveyed 55 cultivated and wild species of the Aurantioideae, analyzing proline and betaines in leaves of mature trees. Some citrus relatives accumulated proline alone; others accumulated proline and proline betaine, as did all Citrus species studied. The levels of these two compounds ranged from about 20 to 100 μmol·g-1 dry mass, and were significantly inversely correlated. Proline betaine is known to be synthesized from proline and to be a better osmoprotectant. Because Citrus species all have more proline than proline betaine, there is scope for engineering more of the latter. Many species had small amounts of hydroxyproline betaine; other betaines were essentially absent. The lack of other betaines means that it would also be rational to engineer the accumulation of glycine betaine or similar compounds.
Botrytis cinerea Decay in Apples Is Inhibited by Postharvest Heat and Calcium Treatments
Authors: Klein Joshua D. , Conway William S. , Whitaker Bruce D. , Sams Carl E.
Published: January 2019

`Golden Delicious' apples (Malus domestica Borkh.) were treated after harvest with heat (air at 38 °C for 4 days or 42 °C for 1 day) or 2% CaCl2 (w/v; applied as a dip or pressure-infiltrated) or a combination of the two and stored at 0 °C for ≤6 months. Decay caused by Botrytis cinerea Pers.:Fr. after inoculation to a depth of 2 mm with a conidial suspension virtually was eliminated in stored fruit heated at 38 °C, regardless of Ca treatment. Apples punctured to a depth of 0.5 mm (but not 2 mm) and inoculated with B. cinerea on removal from storage were almost completely protected from poststorage decay if they had previously been pressure-infiltrated with 2% CaCl2, regardless of the heat regime. Heating fruit at 42 °C and dipping in 2% CaCl2 were only partially effective in preventing decay from either pre- or poststorage inoculations. Fruit firmness was not related to resistance to decay.
The Effect of Growth Regulators and Antibiotics on Eggplant Transformation
Authors: Billings Sharon , Jelenkovic Gojko , Chin Chee-Kok , Eberhardt Jodi
Published: January 2019

A protocol with a high rate of transformation and regeneration of `Hibush' eggplant (Solanum melongena L.) has been developed. This protocol used leaves of in vitro-grown seedlings as a source of explants. The shoot regeneration culture medium contained 0.1 μm thidiazuron (TDZ) combined with 10 to 20 μm N6-[isopentyl] adenine (2iP). Adding TDZ significantly improved regeneration efficiency and produced a mean of 15 buds and 3 to 4 shoots per explant. When explants were cocultivated with Agrobacterium tumefaciens strains Q10, Q20, Q30, Q40, Q201, Q202, Q203, or Q204 containing the native cryIIIB Bacillus thuringiensis (Bt), neomycin phosphotransferase (NPTII), and β-glucuronidase (uidA) genes, a callus/bud regeneration frequency of 38.8% was observed on the selection medium. Kanamycin at 50 μg·mL-1 was most effective in selecting for transgenic buds and shoots. Augmentin at 300 μg·mL-1 was used to eliminate A. tumefaciens. Augmentin also enhanced shoot proliferation. A transformation/regeneration efficiency of 20.8% was observed for shoot production. More than 400 putative transgenic plants have been produced with this method. From 50 putative transgenic plants, gene integration has been confirmed with Southern blot analysis and progeny tests.
Characterizing the Interference between Two Comoviruses in Cowpea
Authors: Eastwell Kenneth C. , Kalmar Gabriel B.
Published: January 2019

In certain cultivars of cowpea [Vigna unguiculata (L.) Walp.] that are operationally immune to cowpea mosaic virus strain SB (CPMV), coinoculation of CPMV with cowpea severe mosaic virus strain DG (CPSMV) reduces severity and delays expression of symptoms normally induced by CPSMV alone. In cultivars susceptible to both viruses, coinoculation delays development of symptoms in response to CPSMV. Using monoclonal antibodies for serological assays and virus-specific RNA probes for hybridization, it is demonstrated that the presence of CPMV in the inoculum yields a concomitant delay in the synthesis of CPSMV coat protein and replication of CPSMV RNA and restricts the transport of CPSMV out of infection centres. Only bottom component of CPMV containing RNA1 is required to offer protection against CPSMV. Destroying the integrity of CPMV RNA eliminates its protective capability. In cowpea cultivars that are operationally immune to CPMV, the presence of CPSMV in the inoculum is unable to compensate for events of CPMV replication that are inhibited. The lack of complementation suggests a high degree of specificity in the replication of these two comoviruses.
Root Respiration and Phosphorus Nutrition of Tomato Plants Grown at a 36 °C Root-zone Temperature
Authors: Klock Kimberly A. , Taber Henry G. , Graves William R.
Published: January 2019

Growth of tomato (Lycopersicon esculentum Mill.) plants decreases at root-zone temperatures (RZTs) >30 °C, but no research has been conducted on the effects of changes in root respiration on P acquisition at supraoptimal RZT. We monitored the changes every 3 to 5 days in root respiration, root surface phosphatase activity, and P acquisition of `Jet Star' tomato plants grown in Hoagland's no. 1 solution held at 25 and 36 °C RZT for 19 days. Root respiration rate in plants grown at 25 °C increased linearly from RZT initiation to day 12, but there was no difference in respiration between days 12 and 19. Root respiration at 36 °C, however, increased from RZT initiation to day 8 and then decreased. Shoot P concentration and root phosphatase activity for plants grown at 25 °C did not change during the experiment. Shoot P concentration for plants at 36 °C, however, linearly decreased over time, and root phosphatase activity linearly increased over time. Decreased shoot growth and demand for P along with decreased root respiration after day 8 probably resulted in the decreased P uptake and shoot P concentration in plants grown at 36 °C RZT.
Freeze Resistance of Pacific Northwest Strawberry Flowers
Authors: Hummel Rita L. , Moore Patrick P.
Published: January 2019

The roles of freeze avoidance and freeze tolerance in determining strawberry (Fragaria ×ananassa) flower freeze resistance were compared in laboratory freeze tests. Genotype, freezing point depression of expressed cell sap, and flower size were examined as potential sources of variation in freeze resistance. When ice was added as a nucleator to excised flowers, mean freeze damage was 97% at -3.0 °C, but in the absence of ice, flowers appeared to supercool and had only 15% damage at -4.0 °C. Without nucleation, cultivar differences in freeze damage were significant in three of four freezing temperatures, but the relative ranking of cultivar freeze damage was not consistent across temperatures. Cultivars that sustained the least amount of injury at -4 °C, were not necessarily the least injured at -7 °C. With an ice nucleator, damage occurred at warmer temperatures (-1.5 °C), but there was no relationship between percentage damage at -1.5 °C with nucleation and -4 °C without nucleation across cultivars. Freezing-point depression of expressed cell sap did not account for the variation in freeze resistance. In nucleated and nonnucleated treatments, larger flowers were more likely to be freeze damaged. Results of this research suggest that flowers of all cultivars are susceptible to freeze damage and survive spring frosts by freeze avoidance.
Elevated Carbon Dioxide Exposure Alters Intracellular pH and Energy Charge in Avocado Fruit Tissue
Authors: Lange Diana L. , Kader Adel A.
Published: January 2019

Changes in cytosolic and vacuolar pH, ATP, ADP, and the ATP : ADP ratio were measured in whole fruit or mesocarp disks of avocado [Persea americana (Mill.) cv. Hass] during brief exposures to elevated CO2. Intact climacteric fruit exposed to air (21% O2), 20% CO2 (17% O2, balance N2), or 40% CO2 (13% O2, balance N2) had cytosolic pH values of 7.0, 6.6, and 6.4, respectively, while mesocarp disks had cytosolic pH values of 6.9, 6.7, and 6.4, respectively. The ß-ATP levels of intact climacteric fruit exposed to 20% CO2 or 40% CO2 for 2 h were reduced by 25% or 43%, respectively, relative to air-exposed fruit. HPLC analysis of nucleotide phosphates from preclimacteric avocados revealed that ATP levels and the ATP : ADP ratio increased in 40% compared to the air-stored fruit. However, 1 day after transfer to air, the effects of elevated CO2 had dissipated. These modifications in cellular state could alter the activity of respiratory enzymes in fruit exposed to elevated CO2 atmospheres.