bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Assimilation and Carbohydrate Metabolism of `Concord' Grape (Vitis labrusca L.) Leaves in Response to Nitrogen Supply
Authors: Chen Li-Song , Cheng Lailiang
Published: January 2019

One-year-old grapevines (Vitis labrusca L. `Concord') were supplied twice weekly for 5 weeks with 0, 5, 10, 15, or 20 mm nitrogen (N) in a modified Hoagland's solution to generate a wide range of leaf N status. Both light-saturated CO2 assimilation at ambient CO2 and at saturating CO2 increased curvilinearly as leaf N increased. Although stomatal conductance showed a similar response to leaf N as CO2 assimilation, calculated intercellular CO2 concentrations decreased. On a leaf area basis, activities of key enzymes in the Calvin cycle, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), NADP-glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoribulokinase (PRK), and key enzymes in sucrose and starch synthesis, fructose-1,6-bisphosphatase (FBPase), sucrose phosphate synthase (SPS), and ADP-glucose pyrophosphorylase (AGPase), increased linearly with increasing leaf N content. When expressed on a leaf N basis, activities of the Calvin cycle enzymes increased with increasing leaf N, whereas activities of FBPase, SPS, and AGPase did not show significant change. As leaf N increased, concentrations of glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), and 3-phosphoglycerate (PGA) increased curvilinearly. The ratio of G6P/F6P remained unchanged over the leaf N range except for a significant drop at the lowest leaf N. Concentrations of glucose, fructose, and sucrose at dusk increased linearly with increasing leaf N, and there was no difference between predawn and dusk measurements. As leaf N increased, starch concentration increased linearly at dusk, but decreased linearly at predawn. The calculated carbon export from starch degradation during the night increased with increasing leaf N. These results showed that 1) grapes leaves accumulated less soluble carbohydrates under N-limitation; 2) the elevated starch level in low N leaves at predawn was the result of the reduced carbon export from starch degradation during the night; and 3) the reduced capacity of CO2 assimilation in low N leaves was caused by the coordinated decreases in the activities of key enzymes involved in CO2 assimilation as a result of direct N limitation, not by the indirect feedback repression of CO2 assimilation via sugar accumulation.
Effect of Heat or 1-Methylcyclopropene on Antioxidative Enzyme Activities and Antioxidants in Apples in Relation to Superficial Scald Development
Authors: Shaham Zohar , Lers Amnon , Lurie Susan
Published: January 2019

`Granny Smith' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] were harvested in two seasons and stored at 0 °C air storage with no pretreatment (control), after heating for 4 d at 38 °C, or after treating for 16 hours at 20 °C with 1 μL·L-1 1-methylcyclopropene (1-MCP). The effects of the two treatments on superficial scald development were consistent over both seasons. Scald began to appear after 8 weeks in control fruit, after 16 weeks in heated fruit but not on 1-MCP treated fruit. α-Farnesene accumulation and oxidation were slower in the skin of heated than in control fruit, and almost entirely absent in 1-MCP treated fruit. The activities of five antioxidant enzymes, ascorbate peroxidase, catalase, glutathione reductase, peroxidase and superoxide dismutate, were measured at two-week intervals in the apple peel, quantitatively as total activity and qualitatively by isozyme analysis. Enzyme activities either increased or remained stable during 16 weeks of storage, except for superoxide dismutase activity, which decreased. Ascorbate oxidase activity was higher in heated than control apples and there was an additional peroxidase isozyme present in activity gels. The activities of antioxidant enzymes were lower in 1-MCP treated fruit except for catalase during the first month of storage. Lipid soluble antioxidant activity was higher in 1-MCP treated fruit than the fruit of the other treatments, and water soluble antioxidant activity was higher in both treatments than in control fruit during the time that scald was developing in control apples. Both free and total phenol contents in the peel fluctuated during storage but no consistent trend was detected. The differences in enzyme activity and antioxidant content of the peel of 1-MCP and heated apples may play a role in preventing or delaying the appearance of superficial scald.
Anthocyanin Degradation in Detached Pome Fruit with Reference to Preharvest Red Color Loss and Pigmentation Patterns of Blushed and Fully Red Pears
Authors: Steyn W.J. , Holcroft D.M. , Wand S.J.E. , Jacobs G.
Published: January 2019

Exposed fruit of `Rosemarie' blushed pear (Pyrus communis L.) displayed daily fluctuations in color in response to temperature while color was more stable in other blushed and fully red cultivars. `Rosemarie' pears increased in redness with the passing of cold fronts, but rapidly lost red color during intermittent warmer periods. Studies on anthocyanin degradation in detached apples and pears indicated that preharvest red color loss was due to net anthocyanin degradation at high temperatures. In support, anthocyanin degradation in attached `Rosemarie' pears corresponded with a warm period during fruit development. Susceptibility to color loss was dependent on the ability of fruit to accumulate anthocyanin. This is due to an exponential relationship between anthocyanin concentration and hue at high pigment levels and a linear relationship at lower pigment levels. Blushed and red pear cultivars that accumulate more anthocyanin with lesser dependence on climatic conditions were less susceptible to fluctuation in color.
Photosynthesis, Chlorophyll Fluorescence, and Carbohydrate Content of Illicium Taxa Grown under Varied Irradiance
Authors: Griffin Jason J. , Ranney Thomas G. , Pharr D. Mason
Published: January 2019

Tolerance to high solar irradiation is an important aspect of stress tolerance for landscape plants, particularly for species native to understory conditions. The objective of this study was to evaluate differential tolerance to high solar irradiation and underlying photosynthetic characteristics of diverse taxa of Illicium L. grown under full sun or 50% shade. Eleven commercially available taxa of Illicium were evaluated for light tolerance by measuring light-saturated photosynthetic capacity (Amax), dark-adapted quantum efficiency of photosystem II (Fv/Fm), and relative chlorophyll content using a SPAD chlorophyll meter. Comparisons of Amax indicated that three of the 11 taxa (I. anisatum L., I. parviflorum Michx. ex Vent., and I. parviflorum `Forest Green') maintained similar rates of light-saturated carbon assimilation when grown in either shade or full sun. All other taxa experienced a significant reduction in Amax when grown in full sun. Chlorophyll fluorescence analysis demonstrated that Fv/Fm was similar between sun and shade plants for the same three taxa that were able to maintain Amax. These taxa appeared to experience less photoinhibition than the others and maintained greater maximum photochemical efficiency of absorbed light. SPAD readings were not significantly reduced in these three taxa either, whereas most other taxa experienced a significant reduction. In fact, SPAD readings were significantly higher in I. parviflorum `Forest Green' when grown under full sun, which also maintained the highest Amax of all the taxa. These results suggest that there is considerable variation in light tolerance among these taxa, with I. parviflorum `Forest Green' demonstrating superior tolerance to high light among the plants compared. A more rigorous examination of I. parviflorum `Forest Green' (high light tolerance) and I. floridanum Ellis (low-light tolerance) demonstrated that I. parviflorum `Forest Green' had a considerably higher Amax, a higher light saturation point, greater potential photosynthetic capacity, reduced susceptibility to photoinhibition as indicated by superior PSII efficiency following light exposure, greater capacity for thermal de-excitation as indicated by a higher rate of nonphotochemical quenching (NPQ) under full sun, greater apparent electron transport rate (ETR) at mid-day, and higher concentrations of the free-radical scavenger myo-inositol. All of these factors contribute potentially to a greater capacity to use light energy for carbon fixation while minimizing photodamage.
Systematics of Alnus maritima (Seaside Alder) Resolved by ISSR Polymorphisms and Morphological Characters
Authors: Schrader James A. , Graves William R.
Published: January 2019

Alnus maritima (Marsh.) Muhl. ex Nutt. is a rare woody plant species that exists as three subspecies found in widely disjunct locations in the United States. Although there is a growing interest in the phytogeography, ecology, conservation, and landscape potential of this species, the phylogeny of A. maritima has not yet been resolved by using molecular methods. We have combined a relatively new method of genome fingerprinting, ISSR-PCR, and the automated imaging capabilities of GeneScan technology to investigate the molecular systematics of A. maritima. Based on the molecular evidence from 108 ISSR loci, we confirm that the three disjunct populations of A. maritima have diverged sufficiently to be classified as subspecies. Our molecular phylogeny of the three subspecies of A. maritima agreed in topology with a phylogeny produced from morphological data and showed that subsp. oklahomensis is the most distinct of the three subspecies and was the first to diverge. The simultaneous analysis of molecular and morphological data provides a detailed and balanced phylogeny reconstruction for the three subspecies. Our results support the theory that A. maritima originated in Asia, migrated into North America across the Bering land bridge, and was established over a large range in the New World before being forced into its present meager disjunct distribution.
Patterns of Floral Nectar Production of Onion (Allium cepa L.) and the Effects of Environmental Conditions
Authors: Silva Erin M. , Dean Bill B. , Hiller Larry
Published: January 2019

Successful pollination of onion (Allium cepa L.) flowers greatly depends on adequate nectar production. In order to understand the nectar production dynamics of onion flowers, nectar was collected at regular intervals during a 24-hour period. Hourly nectar volumes were compared to a variety of environmental conditions, including amount of solar radiation, relative humidity, temperature, wind speed, and evapotranspiration. Production patterns showed mid- to late-morning peaks and late evening peaks in nectar volume. Nectar appeared to be reabsorbed by the flowers during the afternoon and overnight hours. Individual flowers produced the highest amount of nectar several days after initially opening. Nectar production was significantly and inversely related to relative humidity while the effects of temperature, evapotranspiration, wind speed and solar radiation on nectar production were not significant in this study.
Micropropagation and Field Evaluation of the Pear (Pyrus communis L.) `IGE 2002', A New Selection of the Cultivar Dr. Jules Guyot
Authors: Iglesias Ignasi , Vilardell Pere , Bonany Joan , Claveria Elisabet , Dolcet-Sanjuan Ramon
Published: January 2019

A new spontaneous mutation of the pear variety Dr. Jules Guyot, named `IGE 2002', was selected from a pear growing area in Catalonia. The clone was established in vitro from a 40-year-old tree, a highly recalcitrant material unable to root by cuttings. An in vitro micropropagation protocol, with an average multiplication rate of 5, a 90% rooting, and an acclimation of 79% of the plantlets, was defined. Self-rooted plants were grown in two experimental stations, covering two distinct fruit growing areas. The main agronomic characteristics of the clone `IGE 2002' were evaluated during six seasons, 1997 to 2002. Blooming and harvest period were at a similar time than `Dr. Jules Guyot'. Soluble solids concentration and acidity are also similar to `Dr. Jules Guyot'. However, at the same harvest time, a lower fruit firmness of `IGE 2002' in comparison to `Dr. Jules Guyot' indicated an advanced ripening. In addition, a finer flesh texture of `IGE 2002' than `Dr. Jules Guyot', distinguished the former from the later variety. Important differences between both plot sites were found on cumulative fruit yield, fruit size, and fruit size distribution, of `IGE2002' grown on its own roots. However, the site did not affect the fruit quality parameters. Superior fruit yields were associated with higher vigor and yield efficiency of the self-rooted variety.
Impact of Two Hydrophilic Acrylic-Based Polymers on the Physical Properties of Three Substrates and the Growth of Petunia ×hybrida `Brilliant Pink'
Authors: Jobin Philippe , Caron Jean , Bernier Pierre-Yves , Dansereau Blanche
Published: January 2019

Hydrophilic polymers or hydrogels have shown potential to increase water retention of media and to reduce irrigation frequency. This property would be particularly useful in the production of fast growing species in which large amounts of water are needed. This study evaluated the effect of two acrylic-based hydrogels on water desorption curve and hydraulic conductivity of substrates and on plant growth. The duration of their effects was also investigated. Rooted cuttings of Surfinia (Petunia ×hybrida `Brilliant Pink') were transplanted into 30-cm pots containing one of three different substrates amended with one of two types of hydrogels, a commercial acrylic polymer, and a commercial acrylic-acrylamide copolymer, and grown for 9 weeks under well watered conditions and then imposed with a drought. Results indicated that both polymer types gave similar results. The substrates' physical properties (air-filled porosity, available water) at potting time were significantly affected by hydrogel addition, but differences vanished within 9 weeks of growth. Hydrogels had no significant effect on the point at which plant wilted and on the substrate's unsaturated hydraulic conductivity. Shoot dry weight was affected by substrate and hydrogel and was positively correlated to water content between container capacity and -10 kPa of water potential, or between container capacity and the soil water potential at plant turgor loss.
Genetic Variability Influences Carotenoid, Vitamin, Phenolic, and Mineral Content in White, Yellow, Purple, Orange, and Dark-orange Carrot Cultivars
Authors: Nicolle Catherine , Simon Gérard , Rock Edmond , Amouroux Pierre , Rémésy Christian
Published: January 2019

Carrot (Daucus carota L.) is ranked among vegetables as the most consumed and the best provitamin A provider. Moreover, carrot also contains vitamins, phenolic compounds, and other antioxidant micronutrients. The influence of carrot genetic background on the content of several micronutrients was investigated. Carotenoids and vitamins (C and E) were analyzed by HPLC in 20 varieties of carrot, and antioxidant activity of carrots was investigated with colorimetric methods (ORAC and Folin-Ciocalteu). There were large differences among cultivars in carotenoid content (0.32 to 17 mg/100 g of fresh weight). In yellow and purple carrots, lutein represents nearly half of the total carotenoids. By contrast, in orange carrots, β-carotene represents the major carotenoid (65%). The concentration of vitamin E ranged from 191 to 703 μg/100 g of fresh weight, whereas the concentration in ascorbic acid ranged from 1.4 to 5.8 mg/100 g. For all these components, dark-orange carrots exhibited the highest values. Significant differences among these 20 varieties were also recorded for mineral and total phenolic compound concentrations. Purple and dark-orange carrots could be preferred to usual carrot varieties to benefit from their specific micronutrients (anthocyanins, carotenoids, or vitamin E). ORAC is a complex reflection of phytomicronutrients but is not tightly linked to vitamin C levels, as shown for white carrots, which are rich in this vitamin.
Hot Water and Elevated CO2 Effects on Proline and Other Compositional Changes in Relation to Postharvest Chilling Injury of `Marsh' Grapefruit
Authors: Ezz Thanaa M. , Ritenour Mark A. , Brecht Jeffrey K.
Published: January 2019

Heat treatments and exposure to elevated CO2 are known to reduce the incidence of chilling injury on grapefruit. In the current study, `Marsh' grapefruit (Citrus paradisi Macf.) were harvested on 17 Jan. or 22 Mar. 1996 and exposed to hot water (HW) dips (48 °C for 120 minutes) or exposed to controlled atmosphere (CA) of 10% or 16% CO2 during the first 3 weeks of an 8-week cold storage period (4.5 °C) to test their effects on the development of peel pitting (i.e., chilling injury) and proline and other compositional changes of the peel and juice. All HW and CA treatments from both harvests greatly reduced the development of peel pitting compared to the control. These treatments were also associated with lower average proline levels in the flavedo during storage. This suggests that HW and elevated CO2 may reduce chilling-induced peel pitting by facilitating proline metabolism in grapefruit flavedo tissue. HW and CA treatments resulted in higher peel total soluble and nonreducing sugar levels, but effects on peel reducing sugar and free amino acid concentrations were not consistent. In the juice, HW reduced titratable acidity (TA) concentrations while CA tended to increase both TA and ascorbic acid concentrations. Compared to the control, CA resulted in a slight decrease in total soluble solids during storage, while the effect of HW was inconsistent.
Studies on Water Transport through the Sweet Cherry Fruit Surface: VIII. Effect of Selected Cations on Water Uptake and Fruit Cracking
Authors: Weichert Holger , von Jagemann Carina , Peschel Stefanie , Knoche Moritz , Neumann Dieter , Erfurth Wilfried
Published: January 2019

Water uptake through the exocarp of intact sweet cherry [Prunus avium (L.)] fruit was determined gravimetrically in an immersion assay (25 °C). Fruit with sealed pedicel/fruit juncture were incubated in water during the first interval (0 to 0.75 hour) and in 10 mm salt solutions of selected cations during the second (0.75 to 1.5 hours) and third interval (1.5 to 2.25 hours) of an experiment. Rates of water uptake (F) were calculated for first, second and third intervals (FI, FII and FIII, respectively) and salt effects indexed by the ratios FII/FI and FIII/FI. AgNO3 (FII/FI = 0.65), NaCl (0.70), BaCl2 (0.67), CdCl2 (0.69), CuCl2 (0.42), HgCl2 (0.58), and SrCl2 (0.69), and the salts of trivalent cations AlCl3 (0.50), EuCl3 (0.58), and FeCl3 (0.49), significantly decreased water uptake into mature `Sam' fruit as compared to the water control (0.87). KCl (0.82), NH4Cl (0.85), CaCl2 (0.75), MgCl2 (0.88), MnCl2 (0.81), and ZnCl2 (0.72) had no effect, LiCl (1.00) increased uptake. Similar data were obtained for FIII/FI. The effect of FeCl3 on water uptake was independent of the presence of CaCl2, AlCl3, or CuCl2, as sequential or simultaneous treatment with these salts reduced water uptake to the same extent as with FeCl3 alone. Increasing FeCl3 concentration up to 1 mm decreased uptake, higher concentrations had no further effect. FeCl3 and CaCl2 to a smaller extent decreased water uptake in developing `Regina' sweet cherry fruit (55 to 91 days after full bloom). FeCl3 had no significant effect on water uptake along the pedicel/fruit juncture, but markedly reduced uptake through the exocarp of all cultivars investigated (`Burlat', `Early Rivers', `Hedelfinger', `Knauffs', `Regina', `Sam', `Summit', and `Van'). Effects of CaCl2 on water uptake were limited to `Burlat', `Early Rivers', and `Hedelfinger'. CaCl2 and FeCl3 both decreased fruit cracking, but FeCl3 was more effective. The mode of action of mineral salts in decreasing water uptake and fruit cracking and their potential for field use are discussed.
Sequence Analysis of the Chalcone Synthase Gene Intron in Four Petunia Jussieu Taxa
Authors: Griesbach R.J. , Beck R.M.
Published: January 2019

The sequence of the intron within the chalcone synthase A gene (ChsA) was used to characterize Petunia integrifolia subsp. integrifolia var. depauperata (Fries) Smith et Downs, P. altiplana Ando et Hashimoto, P. littoralis Smith et Downs, and an unknown taxon from the town of Torres in Brazil. Based upon the intron, the Torres taxon most closely resembled P. integrifolia. The unrooted phylogenetic tree suggested that P. integrifolia was more closely related to P. littoralis than P. altiplana.
Chemical and Geographical Assessment of the Sweetness of the Cultivated Sweetpotato Clones of the World
Authors: Kays Stanley J. , Wang Yan , McLaurin Wayne J.
Published: January 2019

Sweetness, which is known to vary significantly among clones, is the dominant sensory attribute characterizing the flavor of sweetpotatoes [Ipomoea batatas (L.) Lam.]. The relative sweetness of baked roots, expressed as sucrose equivalents, was determined for 272 clones from the U.S. Department of Agriculture National Plant Germplasm System collection. The clones were from 34 countries that collectively produced 93% of the world's sweetpotato production in 2002. Individual clones were separated into five categories based upon the concentration and relative sweetness of individual sugars, expressed numerically as sucrose equivalents per 100 g dry mass: very high ≥38; high 29-37; moderate 21-28; low 12-20; and nonsweet ≤12. Based upon the mean sucrose equivalents of the clones for each country, only 9% of the countries, which accounted for only 2.1% of the total annual production of the countries surveyed, had sweetpotatoes that were classified as very high. While the majority (62%) of the countries surveyed had clones that were categorized as high, they represented only 4.4% of the total production of sweetpotatoes. None of the countries had mean sucrose equivalent values that were categorized as low or nonsweet, although a few individual clones were ranked as low and one as nonsweet. Countries that account for the majority (87%) of the sweetpotatoes grown worldwide had a mean sucrose equivalent ranking of moderate. Sweetness is derived from the composite of endogenous sugars (sucrose, glucose, fructose) and maltose formed via starch hydrolysis during baking. Maltose accounted for only 42% of the average contribution to the total sucrose equivalents. The range in the concentration of individual sugars among clones was substantial as was their contribution to sucrose equivalents. Sucrose equivalents due to maltose in individual clones ranged from 0.6 to 21.9 while endogenous sugars ranged from 6.4 to 46.9. The results indicate that essentially all of the sweetpotato clones tested from around the world were classified as equal to or greater than moderate in sucrose equivalents, and that there is substantial genetic diversity within the genepool such that the potential exists for tailoring the flavor of new cultivars, via significantly increasing or decreasing sugar content, to meet specific consumer preferences and/or product uses.
Inheritance of Heat Tolerance during Reproductive Development in Snap Bean (Phaseolus vulgaris L.)
Authors: Rainey Katy M. , Griffiths Phillip D.
Published: January 2019

The genetic basis for heat tolerance during reproductive development in snap bean was investigated in a heat-tolerant × heat-sensitive common bean cross. Parental, F1, F2, and backcross generations of a cross between the heat-tolerant snap bean breeding line `Cornell 503' and the heat-sensitive wax bean cultivar Majestic were grown in a high-temperature controlled environment (32 °C day/28 °C night), initiated prior to anthesis and continued through plant senescence. During flowering, individual plants of all generations were visually rated and scored for extent of abscission of reproductive organs. The distribution of abscission scores in segregating generations (F2 and backcrosses) indicated that a high rate of abscission in response to heat stress was controlled by a single recessive gene from `Majestic'. Abscission of reproductive organs is the primary determinant of yield under heat stress in many annual grain legumes; this is the first known report of single gene control of this reaction in common bean or similar legumes. Generation means analysis indicated that genetic variation among generations for pod number under heat stress was best explained by a six-parameter model that includes nonallelic interaction terms, perhaps the result of the hypothetical abscission gene interacting with other genes for pod number in the populations. A simple additive/dominance model accounted for genetic variance for seeds per pod. Dominance [h] and epistatic dominance × dominance [l] genetic parameters for yield components under high temperatures were the largest in magnitude. Results suggest `Cornell 503' can improve heat tolerance in sensitive cultivars, and heat tolerance in common bean may be influenced by major genes.
Transfer to Processing Tomato and Characterization of Late Blight Resistance Derived from Solanum pimpinellifolium L. L3708
Authors: Kim Min-Jea , Mutschler Martha A.
Published: January 2019

Late blight [caused by Phytophthora infestans (Mont.) de Bary] causes severe loss of tomato [Solanum lycopersicum L. (formerly Lycopersicon esculentum Mill.)] production in environments favorable to the pathogen. Researchers at the Asia Vegetable Research Development Center (AVRDC) identified resistance to late blight in an accession of S. pimpinellifolium [formerly L. pimpinellifolium (L.) Mill.] that they named accession L3708. This resistance has now been transferred to processing tomato lines, which are resistant to multiple P. infestans isolates. Lab trials, inoculated field trials in New York, and naturally infested field trials in Mexico all indicate that these processing tomato lines are fixed for late blight resistance. Segregation data obtained for resistance in the breeding populations were dependent on the pathogen isolate used for the disease screen. Segregation data do not support the hypothesis of single gene control of the full resistance trait, but instead suggest that more than one gene is involved, and that these genes interact in an epistatic manner.
Production of a Doubled Haploid from a Haploid Pummelo Using Colchicine Treatment of Axillary Shoot Buds
Authors: Yahata Masaki , Kunitake Hisato , Yabuya Tsutomu , Yamashita Kensuke , Kashihara Yukiko , Komatsu Haruki
Published: January 2019

To produce the homozygous strain of a haploid plant derived from small seed-derived seedlings of `Banpeiyu' pummelo (Citrus grandis Osbeck), we carried out colchicine treatment to axillary shoot buds of the haploid. Many shoots with cytochimeras (X+2X and 2X+4X) arose from the colchicine-treated axillary buds. When cytochimeric buds of 2X+4X were top-grafted onto trifoliate orange [Poncirus trifoliata (L.) Raf.], a complete diploid shoot with 18 chromosomes was obtained from the cytochimera. This diploid strain showed vigorous growth compared with the original haploid. The leaf weight per unit area and the stomata size in this diploid were significantly larger than those of the original haploid plant, and were almost equal to those of `Banpeiyu' pummelo. The diploid strain was confirmed to be a doubled haploid of a haploid from `Banpeiyu' pummelo, based on random amplified polymorphic DNA (RAPD) analysis and chromosome composition analysis by chromomycin A3 (CMA) staining.
Inheritance of High Sugars from Tomato Accession PI 270248 and Environmental Variation between Seasons
Authors: Georgelis N. , Scott J.W. , Baldwin E.A.
Published: January 2019

Small-fruited cherry tomato accession PI 270248 [Lycopersicon esculentum Mill. var. cerasiforme (Dunal) A. Gray] with high fruit sugars was crossed to large-fruited inbred line Fla.7833-1-1-1 (7833) (L. esculentum) that had normal (low) fruit sugars. The F1 was crossed to PI 270248 and 7833 to obtain BCP1 and BCP2, respectively, and self-pollinated to obtain F2 seed. The resulting population was used to study the inheritance of high sugars from PI 270248. Continuous sugar level frequency distributions of BCP1, BCP2, and F2 suggest that the trait is under polygenic control. Additive variation was significant, but dominance variation was not. There was a heterozygote × heterozygote type of epistasis present that likely caused the F1 sugar level to skew nearly to the level of the high sugar parent. The F2 mean sugar level was lower than the midparent level. Broad-sense heritability was 0.86. There was a significant line × season (fall, spring) interaction where lines with higher sugars were affected more by seasons than lines with lower sugars. Sugar level, in general, was higher in spring. Higher solar radiation in spring than in fall may explain the sugar level difference between the seasons.
Extended Shelf Life and Quality of Fresh-cut Papaya Derived from Ripe Fruit Treated with the Ethylene Antagonist 1-Methylcyclopropene
Authors: Ergun Muharrem , Huber Donald J. , Jeong Jiwon , Bartz Jerry A.
Published: January 2019

The purpose of the present study was to investigate the role of ethylene action, via use of the ethylene antagonist 1-methylcyclopropene (1-MCP), on the senescence and quality of fresh-cut ripe papaya (Carica papaya L. `Sunrise Solo') fruit. Ripe papaya fruit were treated with 2.5 μL·L-1 1-MCP and immediately processed into fresh-cut slices or left intact. At 2-day intervals over 10 days at 5 °C, continuously stored slices were monitored for ethylene production, firmness, electrolyte leakage, color, sensory changes, and pathogen incidence. Slices freshly prepared from intact fruit stored under identical conditions were measured similarly. Ethylene production did not differ significantly between the treatments, although production rates were slightly but consistently higher in slices from intact control compared with intact 1-MCP-treated fruit. Mesocarp firmness of continuously stored slices and slices from fruit stored intact was significantly retained by 1-MCP. Firmness of continuously stored slices from 1-MCP-treated fruit declined 50% compared with 75% for control slices. Firmness of fresh-cut slices prepared from intact control and 1-MCP-treated fruit at each sampling interval declined 26% and 15%, respectively. Electrolyte leakage remained low and changed little in slices freshly prepared from fruit stored intact. Leakage from continuously stored papaya slices increased after 4 days, and after 6 days controls increased significantly compared with stored slices derived from papaya fruit initially treated with the ethylene antagonist. The flesh color of continuously stored slices or slices prepared from fruit stored intact was influenced by 1-MCP only during the later periods of storage. Microbial counts in stored slices or slices prepared at each sampling were generally unaffected by 1-MCP. Informal sensory analysis indicated that the edible shelf life was 6 days in stored slices from 1-MCP-treated fruit compared with 2 to 3 days for stored slices from control fruit.
Combining Ability for Disease Resistance, Yield, and Horticultural Traits of Cacao (Theobroma cacao L.) Clones
Authors: Cervantes-Martinez Cuauhtemoc , Brown J. Steven , Schnell Raymond J. , Phillips-Mora Wilbert , Takrama Jemmy F. , Motamayor Juan C.
Published: January 2019

Knowledge of genetic differences among commonly cultivated cacao clones, as well as the type of gene action involved for disease resistance, yield, quality, and horticultural traits, are essential for cacao breeders to select parental clones efficiently and effectively. This information is also critical for quantitative geneticists in designing and improving quantitative trait loci (QTL) localization strategies using breeding populations, whether they involve analysis of multiple populations crossed to one common parent or association genetic analysis. The objectives of this research were to 1) verify the genetic identity of parental cacao clones used to produce hybrids for field evaluation at the Centro Agrónomico Tropical de Investigación y Enzeñanza (CATIE), Turrialba, Costa Rica, using molecular marker analysis, and 2) estimate general and specific combining ability (GCA and SCA) of the parental clones for resistance to frosty pod (Moniliophthora roreri Cif. and Par.) and black pod [Phytophthora palmivora (Butl.) Butl.] diseases, total number of pods, vigor (as measured by trunk diameter), and measures of maturity (months to first flowering and pod production). Misidentification of cacao clones was found at three levels. Molecular marker analysis revealed that six parental clones differed in identity to supposedly identical accessions from other germplasm collections. Trees of the parental clone UF 273 consisted of two clearly different genotypes, resulting in two types of progeny, requiring separate designation for correct statistical analysis. Out-crossed progeny, presumably from foreign pollen, and selfed progeny were also found. Two of the traits measured, percent healthy pods and percent pods with frosty pod, showed predominantly additive gene action, while the traits total number of pods and trunk diameter, demonstrated regulation by both additive and nonadditive gene action. Number of months to first flowering and first fruit both showed evidence of predominant regulation by nonadditive gene effects. Crosses of two parental clones, UF 712 and UF 273 Type I, were identified as potential candidates for QTL analysis as breeding populations, given their favorable GCA estimates for frosty pod resistance and total pod production, respectively.
Deficiency of Linolenic Acid in Lefad7 Mutant Tomato Changes the Volatile Profile and Sensory Perception of Disrupted Leaf and Fruit Tissue
Authors: Cañoles Mauricio A. , Beaudry Randolph M. , Li Chuanyou , Howe Gregg
Published: January 2019

Six-carbon aldehydes and alcohols formed by tomato (Lycopersicon esculentum Mill.) leaf and fruit tissue following disruption are believed to be derived from the degradation of lipids and free fatty acids. Collectively, these C-6 volatiles comprise some of the most important aroma impact compounds. If fatty acids are the primary source of tomato volatiles, then an alteration in the fatty acid composition such as that caused by a mutation in the chloroplastic omega-3-fatty acid desaturase (ω-3 FAD), referred to as LeFAD7, found in the mutant line of `Castlemart' termed Lefad7, would be reflected in the volatile profile of disrupted leaf and fruit tissue. Leaves and fruit of the Lefad7 mutant had ≈10% to 15% of the linolenic acid (18:3) levels and about 1.5- to 3-fold higher linoleic acid (18:2) levels found in the parent line. Production of unsaturated C-6 aldehydes Z-3-hexenal, Z-3-hexenol, and E-2-hexenal and the alcohol Z-3-hexenol derived from 18:3 was markedly reduced in disrupted leaf and fruit tissue of the Lefad7 mutant line. Conversely, the production of the saturated C-6 aldehyde hexanal and its alcohol, hexanol, were markedly higher in the mutant line. The shift in the volatile profile brought about by the loss of chloroplastic FAD activity in the Lefad7 line was detected by sensory panels at high significance levels (P < 0.0005) and detrimentally affected fruit sensory quality. The ratios and amounts of C-6 saturated and unsaturated aldehydes and alcohols produced by tomato were dependent on substrate levels, suggesting that practices that alter the content of linoleic and linolenic acids or change their ratios can influence tomato flavor.
Leaf Abscisic Acid Accumulation in Response To Substrate Water Content: Linking Leaf Gas Exchange Regulation with Leaf Abscisic Acid Concentration
Authors: Bauerle William L. , Inman William W. , Dudley Jerry B.
Published: January 2019

Quantitative differences in leaf abscisic acid (ABAL) among four cultivars of red maple (Acer rubrum L.) and one freeman maple (Acer ×freemanii E. Murray) cultivar were investigated. This study tested the hypothesis that ABAL concentration can be used to compare the effects of water stress on the gas exchange response of five different maple genotypes, including four red maple cultivars [`Summer Red', `October Glory', `Autumn Flame', and `Franksred' ('Red Sunset')] and one hybridized freeman maple cultivar ['Jeffersred' ('Autumn Blaze')]. Two-year-old cloned genotypes of red maple and freeman maple were subjected to two treatments: irrigated daily to container capacity or irrigation withheld for one drought and recovery cycle. Leaf abscisic acid concentration, gas exchange, and wholetree sap flow measurements were conducted under well-watered and drought stress conditions. Over the course of the drought stress and recovery phase, net photosynthesis (Anet), stomatal conductance (gs), and transpiration (E) declined as ABAL and instantaneous water use efficiency (A/gs) increased. Until severe water stress conditions were prominent, water use was higher in `Summer Red' as compared to `October Glory'. This study found that ABAL tracked gs and that stomatal responsiveness to substrate moisture deficit is likely mediated by ABA accumulation in leaf tissue. This research demonstrates a leaf level physiological response to substrate volumetric water content that appears to depend on ABAL concentration. In addition, the evidence in this study indicates that ABAL may be used as a potential surrogate for the gs response to substrate water stress and could become part of a cultivar drought tolerance selection strategy for red maple and freeman maple.
Isolation, Characterization, and Evaluation of Microsatellite Loci for Cultivar Identification in the Ornamental Pampas Grass Cortaderia selloana
Authors: Ahmad Riaz , Okada Miki , Firestone Jeffrey L. , Mallek Chris R. , Jasieniuk Marie
Published: January 2019

We isolated and characterized microsatellite loci in the ornamental pampas grass Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn. for purposes of identifying cultivars and assessing genetic relationships among cultivars. Small insert genomic libraries were enriched for dinucleotide (CT)n and (CA)n repeats. Ninety clones were sequenced of which 76% contained at least one microsatellite with a basic motif greater than six repeat units. Nine primer pairs amplified 10 polymorphic and putatively disomic loci, and were used to genotype 88 individuals representing 17 named cultivars and four selections. In total, 93 alleles were detected with a maximum of two to 19 per locus. Effective number of alleles varied from 1.3 to 9.5. Observed heterozygosity ranged from 0.07 to 0.81. The 10 microsatellite loci distinguished the majority of pampas grass cultivars. An unweighted pair group method with arithmetic mean (UPGMA) cluster analysis, based on proportion of shared alleles among individuals, revealed groups of cultivars corresponding to origin and morphological characteristics. With few exceptions, individuals of a single cultivar clustered together with moderate to strong bootstrap support (greater than 50%). Interestingly, `Pumila' from Europe and the United States formed separate clusters indicating independent origins. A large, diverse cluster with low bootstrap support consisted of selections and cultivars sold as seed, rather than potted or bare-root clonal plants. Primers designed for C. selloana amplified microsatellite loci in other Cortaderia Stapf species concordant with phylogenetic relationships among the species. Cross-amplification was 100% in C. jubata (Lemoine ex Carrière) Stapf; 77% in C. pilosa (d'Urv.) Hack. and C. rudiuscula Stapf; 66% in C. fulvida (Buch.) Zotov; and 55% in C. richardii (Endl.) Zotov and C. toetoe Zotov.
Assessment of SSR Marker Transfer from the Cultivated Strawberry to Diploid Strawberry Species: Functionality, Linkage Group Assignment, and Use in Diversity Analysis
Authors: Davis Thomas M. , DiMeglio Laura M. , Yang Ronghui , Styan Sarah M.N. , Lewers Kim S.
Published: January 2019

The cultivated strawberry, Fragaria ×ananassa Duchesne ex Rozier, originated via hybridization between octoploids F. chiloensis (L.) Mill. and F. virginiana Mill. These three octoploid species are thought to share a putative genome composition of AAA`A'BBB`B'. Diploid F. vesca L., is considered to have donated the A genome. Current attention to the development of a diploid model system for strawberry genomics warrants the assessment of simple sequence repeat (SSR) marker transferability between the octoploid and diploid species in Fragaria L. In the present study, 23 SSR primer pairs derived from F. ×ananassa `Earliglow' by genomic library screening were evaluated for their utility in six diploid Fragaria species, including eight representatives of F. vesca, four of F. viridis Weston, and one each of F. nubicola (Hook. f.) Lindl. ex Lacaita, F. mandshurica Staudt, F. iinumae Makino, and F. nilgerrensis Schltdl. ex J. Gay. SSR primer pair functionality, as measured by amplification success rate (= 100% - failure rate) in each species, was ranked (from highest to lowest) as follows: F. vesca (98.4%) > F. iinumae (93.8%) = F. nubicola (93.8%) > F. mandshurica (87.5%) > F. nilgerrensis (75%) > F. viridis (73.4%). The extent to which these octoploid-derived SSR primer pairs generated markers that could be added to the F. vesca linkage map also was assessed. Of the 13 F. ×ananassa SSR markers that segregated codominantly in the F. vesca mapping population, 11 were assigned to linkage groups based upon close linkages to previously mapped loci. These markers were distributed over six of the seven F. vesca linkage groups, and can serve as anchor loci defining these six groups for purposes of comparative mapping between F. vesca and F. ×ananassa.
Global Analysis of Genes Regulated by Low Temperature and Photoperiod in Peach Bark
Authors: Bassett Carole L. , Wisniewski Michael E. , Artlip Timothy S. , Norelli John L. , Renaut Jenny , Farrell Robert E.
Published: January 2019

In response to environmental cues plants undergo changes in gene expression that result in the up- or down-regulation of specific genes. To identify genes in peach [Prunus persica (L.) Batsch.] trees whose transcript levels are specifically affected by low temperature (LT) or short day photoperiod (SD), we have created suppression subtractive hybridization (SSH) libraries from bark tissues sampled from trees kept at 5 °C and 25 °C under short day (SD) photoperiod or exposed to a night break (NB) interruption during the dark period of the SD cycle to simulate a long day (LD) photoperiod. Sequences expressed in forward and reverse subtractions using various subtracted combinations of temperature and photoperiod treatments were cloned, sequenced, and identified by BLAST and ClustalW analysis. Low temperature treatment resulted in the up-regulation of a number of cold-responsive and stress-related genes and suppression of genes involved in “housekeeping” functions (e.g., cell division and photosynthesis). Some stress-related genes not observed to be up-regulated under LT were increased in response to SD photoperiod treatments. Comparison of the patterns of expression as a consequence of different temperature and photoperiod treatments allowed us to determine the qualitative contribution of each treatment to the regulation of specific genes.
Characterization of Late Blight Resistance Derived from Solanum pimpinellifolium L3708 against Multiple Isolates of the Pathogen Phytophthora infestans
Authors: Kim Min-Jea , Mutschler Martha A.
Published: January 2019

Sixteen tomato [Solanum lycopersicum L. (syn. Lycopersicon esculentum Mill.)] genotypes (inbred lines or hybrids) were tested against five Phytophthora infestans (Mont.) deBary isolates to characterize race specificity of late blight resistance transferred to tomato from Solanum pimpinellifolium L. [syn. Lycopersicon pimpinellifolium (L.) Mill.] accession L3708. The effects of plant genotype, isolate, genotype × isolate, and isolate × replication interactions were highly significant (P = 0.001). Set of four sister lines fixed for late blight resistance (CU-R lines) exhibited full and equal resistance to the five pathogen isolates tested. In contrast, the heterozygous F1 hybrids, created by crossing the resistant CU-R lines with a susceptible parent, were resistant to US-11; partially resistant to US-17, NC-1, and DR4B; and susceptible to US-7. Differential responses were also observed across pathogen isolates on a set of resistant sister lines (CLN-R lines), which also were bred from L3708. The CLN-R lines were resistant to the DR4B, NC-1, and US-11 isolates, but showed significant disease-affected areas and sporangium numbers following inoculation with either US-7 or US-17. Restriction fragment length polymorphism (RFLP) analysis confirms that both CU-R and CLN-R are homozygous for the Ph-3 gene derived from L3708. Since progeny tests also confirmed that the CLN-R lines are fixed for their level of resistance, these results suggest that late blight resistance in the CU-R lines is not controlled by Ph-3 alone, and that at least one additional gene conferring late blight resistance is missing from the CLN-R lines. Results of genetic tests of the (CU-R × CLN-R) F1 and a (CU-R × CLN-R) F2 population with the pathogen isolate US-17 strongly support a model in which resistance of the CU-R lines requires genes in addition to Ph-3. The implications of this information in breeding for late blight resistance and using of the resulting resistant lines or hybrids are discussed.
Variation Between Cut Chrysanthemum Cultivars in Response to Suboptimal Temperature
Authors: van der Ploeg Anke , Kularathne Ranathunga J.K.N. , Carvalho Susana M.P. , Heuvelink Ep
Published: January 2019

To breed for more energy-efficient cut chrysanthemum (Chrysanthemum morifolium Ramat.) cultivars it is important to know the variation of the temperature response existing in modern cultivars. In a greenhouse experiment with 25 chrysanthemum cultivars, a significant variation was observed in temperature response (16 °C or 20 °C) for reaction time, total dry weight produced, stem length, and flower size and number. To study this genetic variation in temperature response over a larger range of temperatures (15 °C to 24 °C), four contrasting cultivars (Annecy, Delianne, Reagan, and Supernova) were selected in a second experiment. Furthermore, a third experiment was performed in which the cultivation period was split into three phases and the influence of temperature in each of these phases was studied for the four selected cultivars. Dry weight production in all cultivars was very sensitive to temperature during the long day period. Relative growth rate showed an optimum response to temperature, with the optimum around 24 °C. Net assimilation rate also showed an optimum response to temperature, whereas leaf area ratio increased linearly with temperature. Compared with these temperature effects during the long day, the effect of temperature on absolute growth rate during the short day was, depending on the cultivar, relatively small or even absent. The reaction time, on the other hand, was very temperature sensitive, showing an optimum that was cultivar dependent. The temperature response of the total dry weight production during the whole cultivation period was, therefore, very cultivar dependent. Furthermore, depending on the cultivar, stem length increased with temperature, especially during long day, as a result of both increasing internode number and average internode length. The response of both flower size and number to temperature was also highly cultivar specific. The possibilities of using this genetic variation for breeding are discussed.