bluuebunny/crossref_metadata_2025 huggingface dataset:
Macronutrient Allocation to Leaves and Fruit of Mature, Alternate-bearing Pistachio Trees: Magnitude and Seasonal Patterns at the Whole-canopy Level
Authors: Picchioni G.A. , Brown P.H. , Weinbaum S.A. , Muraoka T.T.
Published: January 2019

Estimates of leaflet and fruit macronutrient (N, P, K, Ca, and Mg) accumulation and resorption were developed in six (three heavily cropping, on-year and three noncropping, off-year) mature pistachio (Pistacia vera L. `Kerman') trees over three growing seasons during three stages of phenology [the spring growth flush (April to June); seed fill (late June to September); and leaf senescence (September to November)]. Crop load influenced total nutrient content per tree in annual organs (leaves and fruit), the relative allocation of nutrients between leaves and fruit, temporal patterns of nutrient accumulation in annual organs, and the magnitude of net leaf nutrient resorption per tree prior to leaf fall. In off-year trees, macronutrient accumulation in annual organs (leaves) was concentrated during the spring flush of growth. In contrast, significant macronutrient accumulation in annual organs of on-year trees (leaves plus fruit) occurred not only during the spring flush of growth but also during seed fill. Duration and magnitude of macronutrient accumulation were greater in on-year vs. off-year trees. Fruit N and P demand during seed fill was partially met by a net decrease in the N and P contents of the pericarp. These decreases in pericarp nutrient content during seed fill were equivalent to 32% and 26% of embryo accumulation of N and P, respectively. Fruit demand for N, P, and K during the spring flush of “on” years was accompanied by reduced leaf N, P, and K contents per tree. Net leaf N, Ca, and Mg resorption per tree during leaf senescence differed with crop load. Net leaf N resorption was significantly greater in off-year trees than on-year trees. Leaf N resorption presumably represents an important component of the N pool stored in perennial tree parts during dormancy. The greater leaf N resorption following “off” years was a function of greater leaf N concentration and greater leaf biomass per tree. In contrast, net leaf resorption of Ca and Mg was greater in on-year vs. off-year trees. Experimental validation of the magnitude and periodicity of nutrient uptake by mature pistachio trees is needed during the alternate-bearing cycle, especially in light of the potential contribution of current fertilization practices to groundwater contamination.
The Effect of Root Media on Root-zone pH, Calcium, and Magnesium Management in Containers with Impatiens
Authors: Argo William R. , Biernbaum John A.
Published: January 2019

Hybrid impatiens (Impatiens Wallerana Hook. F.) were planted in six root media containing either 70% (by volume) rockwool, coir, or four types of sphagnum peat and 30% perlite. The six media varied in cation exchange capacities (CEC) (from 5 to 76 meq·L-1) and the amount of a dolomitic hydrated lime [Ca(OH)2 and Mg(OH)2 at 0 to 4.5 kg·m-3) required to obtain an initial pH of ≈6.0. Two additional treatments were produced by using a dolomitic carbonate lime (CaCO3 and MgCO3) at 8.4 kg·m-3 instead of the hydrated lime in two of the sphagnum peat media. Plants were subirrigated for 17 weeks using three nutrient solutions (NS) that contained at 200N-20P-200K mg·L-1 but had a variable NH4 : NO3 ratio and Ca2+ and Mg2+ content. The NS were designed to produce either acidic, neutral, or basic reactions in the medium. In media containing the hydrated lime, the NS was the primary factor controlling medium pH. However, within each NS treatment, the media did have some effect on buffering the pH over time. There was a linear increase in shoot-tissue Ca and Mg as the applied concentration of Ca2+ increased from 18 to 156 mg·L-1 and that of Mg2+ increased from 5 to 56 mg·L-1. Linear regression analysis of shoot-tissue Ca and Mg based on their concentration in the NS indicated a similar overall decrease in the Ca and Mg supply in all six root media over time. For plants grown in media containing the carbonate lime, shoot dry mass was similar to that of plants grown in the same media with hydrated lime. The presence of the carbonate lime in the media increased the pH buffering capacity against decreasing pH with the acidic and neutral NS but not against increasing pH with the basic NS. In the media containing the carbonate lime and given the acidic NS, root-medium and shoot-tissue Ca and Mg increased by weeks 12 and 17 compared to that of the same medium containing the hydrated lime. There were minimal differences in root-media and shoot-tissue Ca and Mg concentration between lime treatments when given the neutral or basic NS.
Factors Affecting Agrobacterium-mediated Transformation of Common Bean
Authors: Zhang Zhanyuan , Coyne Dermot P. , Mitra Amitava
Published: January 2019

Factors influencing Agrobacterium tumefaciens-mediated transformation of common beans (Phaseolus vulgaris L.) were examined using an intron-containing β-glucuronidase (GUS) gene as a reporter system to develop a repeatable transformation protocol. Tissue culture procedures used were based on direct shoot organogenesis. Two A. tumefaciens strains—A2760 and EHA105—were used, with emphasis on the former due to its overall higher infection rate. Eleven common-bean genotypes were compared for susceptibility to strain A2760 or EHA105. The pinto bean `Othello' was used extensively in testing different transformation conditions. Factors significantly affecting transformation rate were Agrobacterium × host interactions, explant maturity, preculture and cocultivation conditions, and selection schemes, based on transient GUS gene expression. The best transformation conditions were the use of susceptible genotypes and explants derived from mature seeds, preconditioning of explants in a medium containing 20 μmol of benzyladenine (BA) in darkness or on a filter paper, dipping explants in high concentrations of Agrobacterium cell suspension (OD650 = 0.8-1.0) followed by a long-term (6-day) cocultivation period on a semisolid agar medium in the presence of cytokinin or 3-day cocultivation on a moistened filter paper, and the use of lethal levels of selective agents. About 4% of explants, or 14% of regenerated shoots or buds, were putatively transgenic, as indicated by GUS blue staining throughout the entire shoot or bud, after explants were transformed with Agrobacterium strain A2760 using an optimized protocol.
Inhibition or Promotion of Tomato Fruit Ripening by Acetaldehyde and Ethanol is Concentration Dependent and Varies with Initial Fruit Maturity
Authors: Beaulieu John C. , Saltveit Mikal E.
Published: January 2019

`Castlemart' tomato (Lycopersicon esculentum Mill.) pericarp discs were used to study the physiological effects of acetaldehyde and ethanol on fruit ripening. Short-term exposure of discs from mature-green fruit to acetaldehyde vapors on a fresh mass basis (≤500 μg·g-1) or ethanol vapors (≤3 mg·g-1) promoted ripening, while higher concentrations inhibited ripening. Discs from mature-green fruit absorbed greater amounts of ethanol and produced significantly higher concentrations of acetaldehyde than discs from breaker fruit. Ripening was promoted by ethanol when the discs were unable to retain or produce a certain level of acetaldehyde. Inhibition of ripening by 4 hours of exposure to ethanol (6 mg·g-1) was almost completely abolished by hypobaric treatments (18 kPa for 24 hours). However, acetaldehyde-induced ripening inhibition (2 days exposure to 180 μg·g-1) was only slightly reduced by vacuum. Concentrations of acetaldehyde and ethanol that inhibited ripening reduced C2H4 production, whereas lower concentrations of acetaldehyde and ethanol that promoted ripening increased C2H4 production. Application of 4-methylpyrazole, an alcohol dehydrogenase inhibitor, enhanced acetaldehyde-induced ripening inhibition and reduced ethanol-induced ripening inhibition or promotion at all concentrations of acetaldehyde and ethanol tested. The inhibition or promotion of ripening of excised tomato pericarp discs by ethanol and acetaldehyde depended on initial fruit maturity, applied volatile concentration, and duration of exposure.
Fall Foliar-applied Boron Increases Tissue Boron Concentration and Nut Set of Almond
Authors: Nyomora Agnes M.S. , Brown Patrick H. , Freeman M.
Published: January 2019

Fruit set is the major determinant of productivity in almond [Prunus dulcis (Mill D.A. Webb)] where seed is the commercial product. Boron influences flowering and fruit set in a number of crops, but little has been reported on this subject in almond. Here, we investigated the effect of a fall foliar application of B on fruit set and tissue B concentration in open pollinated `Butte' and `Mono' almond over a 2-year period. Early fall B application significantly increased the vegetative, floral, and fruit tissue B concentration in the subsequent year. The greatest increase in organ B concentration was observed in flower buds, flowers, and hulls. Recent work has demonstrated that B forms a B-sorbitol complex in Prunus species. This B-sorbitol complex is phloem mobile and is transported to sink organs. Here we demonstrate that fall-applied B is absorbed by the leaf and is subsequently transported (presumably as the B-sorbitol complex) to floral buds where it is available to flowers and, hence, influences fruit set and yield. It is concluded that fall foliar-applied B is a useful fertilization strategy that can be used to optimize tissue B concentration in species in which B is phloem mobile. Boron applied at 245 and/or 490 ppm significantly increased fruit set in `Butte' and `Mono' and increased yield of `Butte' in 1994 on open-pollinated trees (yield was not determined in 1993). The highest initial and second fruit set was associated with either the 245 or 490 ppm B treatments in both cultivars and both years. This increased fruit set resulted in yield increases of 53% and 4%, respectively, for `Butte' and `Mono'. Of the two cultivars, `Butte', which had lower tissue B concentration before B application, responded more significantly in yield to B application. Application of 735 ppm B was less effective than either 245 and 490 ppm B; however, no visual symptoms of excess B were observed.
Sugar Use in Relation to Shoot Induction by Sorbitol and Cytokinin in Apple
Authors: Karhu Saila T.
Published: January 2019

Microshoots of `McIntosh' apple (Malus domestica Borkh.) were grown on Murashige-Skoog (MS) nutrient medium supplemented with either sucrose or sorbitol or with sucrose and an elevated level of cytokinin. Shoot growth was recorded and concentrations of fructose, glucose, sorbitol, and sucrose were analyzed in nutrient media and shoots during a 6-week subculture period. Axillary branching was stimulated by high cytokinin and sorbitol media, with increased biomass production and carbohydrate use on the high-BA medium only. The sucrose in the nutrient medium was hydrolyzed to fructose and glucose, which were equally taken up by shoots. Sorbitol was taken up somewhat less effectively. The elevated level of BA decreased sucrose hydrolysis in the nutrient medium. There were high concentrations of sorbitol in shoots grown on the sorbitol medium, and sorbitol also accumulated at the end of the culture period in shoots grown on sucrose. The amount of sucrose was low, and glucose was more abundant than fructose in microshoots. The starch content of leaves was not affected by treatments or sampling time. Chemical names used: N6-benzyladenine (BA).
Oxidative Stress and Diurnal Variation in Chilling Sensitivity of Tomato Seedlings
Authors: Kerdnaimongkol Kanogwan , Bhatia Anju , Joly Robert J. , Woodson William R.
Published: January 2019

Diurnal variation in the chilling sensitivity of `Rutgers' tomato (Lycopersicon esculentum Mill.) seedlings was examined. Chilling sensitivity was highest in seedlings chilled at the end of the dark period, and these seedlings became more resistant to chilling injury on exposure to the light. The development of chilling tolerance in tomato seedlings was a response to light and not under the control of a circadian rhythm. The recovery of leaf gas exchange following chilling was faster in seedlings chilled at the end of the light period. Diurnal variation in chilling sensitivity was associated with changes in catalase and superoxide dismutase activities. An increase in catalase and superoxide dismutase activities was observed at the end of the light period. Catalase activity was significantly higher in all stages of chilling following the light period compared to those chilled after the end of the dark period. Forty-eight hours of 14 °C acclimation or pretreatment with hydrogen peroxide conferred increased chilling tolerance to tomato seedlings. Hydrogen peroxide-treated seedlings showed little evidence of a diurnal variation in chilling sensitivity. These results support a role for light and oxidative stress in conferring increased chilling tolerance to tomato seedlings.
Leaf Water Relation Parameters in Almond Compared to Hazelnut Trees during a Deficit Irrigation Period
Authors: Marsal Jordi , Girona Joan , Mata Mercè
Published: January 2019

The influence of deficit irrigation on predawn leaf water potential (Ψpd) and leaf gas-exchange parameters was analyzed in almond [Prunus dulcis (Mill.) D.A. Webb] and compared to hazelnut (Corylus avellana L.). Both species were planted in adjacent plots in which four irrigation treatments were applied: T-100%, T-130%, and T-70%, which were irrigated at full crop evapotranspiration (ETc), 1.3 × ETc, and 0.7 × ETc, respectively, and a regulated deficit irrigation (RDI) treatment, which consisted of full irrigation for the full season, except from middle June to late August when 0.2 × ETc was applied. Under nonstressful conditions, hazelnut had a lower net CO2 assimilation rate (A) (12.2 μmol·m-2·s-1) than almond (15.5 μmol·m-2·s-1). Reductions in net CO2 assimilation rate (A) induced by decreases in Ψpd were higher in hazelnut than in almond. Gas-exchange activity from early morning to midday decreased in hazelnut for all irrigation treatments, but in almond increased in the well-watered treatments and decreased slightly or remained constant in the RDI. Hazelnut had a higher A sensitivity to variations in stomatal conductance (gs) than almond, especially at low gs values. The Ψpd values in almond and hazelnut of the T-100% and T-130% treatments were affected by decreasing values in midsummer, but in hazelnut Ψpd was probably also affected by sink kernel filling. These facts indicate that hazelnut RDI management could be more problematic than in almond.
Effect of Floricane Number in `Marion' Trailing Blackberry. I. Primocane Growth and Cold Hardiness
Authors: Cortell Jessica M. , Strik Bernadine C.
Published: January 2019

In Spring 1993 and 1994, mature trailing `Marion' blackberries (Rubus L. subgenus Rubus Watson) were pruned to 0, 4, 8, and 12 floricanes/plant. An additional treatment of 0 floricanes with early (30 cm) primocane topping and pruning was included. Primocane length was measured from emergence in April until growth cessation at the end of October on individual canes and for the whole plant. In January 1994 and 1995, cane cold hardiness was evaluated by controlled freezing. In 1993, plants without floricanes produced more primocanes and branches with an increased total length at the end of the season than plants with floricanes. However, there were no significant differences in primocane length among treatments in 1994. In all treatments, the absolute growth rate (AGR), on a length basis, of primocanes occurred in flushes of rapid growth followed by slower growth throughout the season. Plants without floricanes had a significantly greater AGR than plants with floricanes on five dates in 1993. In 1994, there was no effect of floricane number per plant on AGR of primocanes over the season and the growth peaks were not as distinct. When comparing primocane elongation rate at three phenological stages in 1993, plants with no floricanes had a significantly higher total primocane growth per day during fruit production and from harvest to length cessation. The following year, plants with no floricanes had the highest rate of growth before bloom and a trend toward greater growth during fruit production. After fruit production, there were no differences in AGR between the treatments. Plants with floricanes produced a second flush of primocanes, while plants with no floricanes produced only one flush of primocanes. Primocane length of the first flush (averaged for 4-, 8-, and 12-floricane plants) was significantly different from the second flush at all dates during the season except for the final end of season measurement date. Primocanes pruned at 30 cm did not produce significantly more branches than unpruned primocanes on plants without floricanes. Plants without floricanes produced primocanes that were significantly more cold hardy (lower LT50) in 1994 and 1995 than plants with floricanes.
Tight Linkage between the Fin Locus for Plant Habit and the Z Locus for Partly Colored Seedcoat Patterns in Common Bean
Authors: Bassett Mark J.
Published: January 2019

Linkage between the Fin locus controlling plant habit and the Z locus controlling partly colored seedcoats in common bean (Phaseolus vulgaris L.) was studied in the F2 and F3 progenies from the cross `t virgarcus BC3 5-593' (determinate habit, virgarcus pattern of partly colored seeds, fin tz) × `Steuben Yellow Eye' (indeterminate habit, sellatus pattern of partly colored seeds, Fin t zsel). The heterozygous genotype zsel/z produces the piebald pattern of partly colored seeds, whereas Fin is completely dominate to fin. Selection was made in the F2 for crossover phenotypes: indeterminate habit with virgarcus seeds or determinate habit with piebald seeds. Linkage calculations were based on crossover genotypes confirmed by F3 progeny tests grown in the greenhouse. The recombination percentage between Fin and Z was 1.032±0.33 map units. The gene symbol zsel is proposed, where t Z gives the expansa partly colored seedcoat pattern, t zsel gives sellatus, and t z gives virgarcus.
Isozyme and Randomly Amplified Polymorphic DNA (RAPD) Analyses of Cherokee Rose and Its Putative Hybrids `Silver Moon' and `Anemone'
Authors: Walker Charles A. , Werner Dennis J.
Published: January 2019

Two banding patterns were revealed by phosphoglucomutase (PGM) isozyme analysis of 24 accessions of Cherokee rose (Rosa laevigata Michx.) from eight southeastern states, based on the presence (in 5 accessions) or absence (in 19 accessions) of an additional slow-migrating band. RAPD analysis of these accessions showed a corresponding division into the same two groups determined by PGM analysis, except for two accessions with unique RAPD phenotypes. Field-grown accessions showed distinguishing morphological characters corresponding to the groupings from the isozyme and RAPD analyses. Those in the predominant isozyme and RAPD groups, as well as the two with unique RAPD phenotypes, exhibited smooth lateral stems, while those in both nonpredominant groups exhibited markedly bristly laterals. These results suggest that the 24 accessions are ramets of two major clones with one clone predominating and that, contrary to long-standing belief, the Cherokee rose has not naturalized by reseeding in the southeast. PGM and RAPD analyses of putative Cherokee rose hybrids `Anemone' and `Silver Moon' showed that `Anemone' is likely to be such a hybrid but that `Silver Moon' is not. Historical records revealed that widespread vegetative propagation of the Cherokee rose was initiated in 1820-21 and that L. Wiesener, not J.C. Schmidt, was the originator of `Anemone'.
Rootstock Influences Seasonal Dry Matter and Carbohydrate Content and Partitioning in Above-ground Components of `Flordaprince' Peach Trees
Authors: Caruso T. , Inglese P. , Sidari M. , Sottile F.
Published: January 2019

Seasonal development of leaf area, leaf area index (LAI), dry matter, and carbohydrate content were measured from harvest 1992 to harvest 1993 in above-ground components of `Flordaprince' peach [Prunus persica (L.) Batsch] trees grafted on GF 677 (Prunus persica × Prunus amygdalus) and MrS 2/5 (Prunus cerasifera free pollinated) rootstocks, which widely differ in vigor. Whole trees were separated into fruit, leaves, shoots, 1-year-old wood and >1-year-old wood. Sampling dates were coincident with key fruit and tree developmental stages: dormancy, fruit set, pit hardening, and fruit harvest. Rootstock modified the vegetative vigor of the tree, the seasonal partitioning of dry matter, and starch content in above-ground components. Leaf area, LAI, and total above-ground dry matter were twice as high in the most vigorous combination (`Flordaprince'/GF 677), which gave the highest yield, but had the lowest harvest index. Rootstock vigor did not affect soluble sugar concentration in any of the canopy components. Starch content was greatest during dormancy and in the oldest wood of GF 677 trees. During fruit development, starch content rapidly decreased in 1-year-old wood and perennial components; at pit hardening it was four times greater in MrS 2/5 than in GF 677 trees. The vegetative-to-fruit dry mass ratio by pit hardening was 3:1 for MrS 2/5 and 9:1 for GF 677 trees. Competition with shoot growth apparently reduced fruit growth, particularly during Stage I and Stage II, as fruit size at harvest was significantly lower (17%) in GF 677 than in MrS 2/5 trees.
Changes to Physical Properties of the Cell Wall and Polyuronides in Response to Heat Treatment of `Fuyu' Persimmon that Alleviate Chilling Injury
Authors: Woolf Allan B. , MacRae Elspeth A. , Spooner Karen J. , Redgwell Robert J.
Published: January 2019

Modifications to solubilized cell wall polyuronides of sweet persimmon (Diospyros kaki L. `Fuyu') were examined during development of chilling injury (CI) during storage and in response to heat treatments that alleviated CI. Storage at 0 °C caused the solubilization of a polyuronide fraction that possessed a higher average molecular mass than polyuronide solubilized during normal ripening. The viscosity of this fraction was 30-times that of normally ripened fruit. Fruit heat-treated before or following storage contained a soluble polyuronide fraction with a markedly lower average molecular mass and decreased viscosity than in chilling injured fruit. Heat treatment also impeded an increase in viscosity of the cell wall material if applied before storage. CI (gelling) was related to the release of polyuronide from the cell wall during storage and its lack of subsequent degradation. Heat treatments retarded polyuronide release but promoted degradation of solubilized polyuronides.
Enumeration and Inoculation of Nitrifying Bacteria in Soilless Potting Media
Authors: Lang Harvey J. , Elliott George C.
Published: January 2019

Autotrophic nitrifying organisms were enumerated in soilless potting media using the most probable number (MPN) technique. Populations of NH4+ and NO2- oxidizing organisms varied widely between two soilless media—Metro-Mix 220 and 350. Estimates for NH4+ oxidizing organisms ranged from 0.7 to 7.8 × 105 organisms/cm3, while NO2- oxidizers ranged from 1.3 to 9.5 × 105 organisms/cm3. Population numbers were similar to those typically reported in soils. There was a significant effect of medium type, NH4+ N : NO3- N fertilizer ratio, and planting on MPN counts of both groups of organisms, with significant interaction between several of the factors. Estimates of NH4+ oxidizers were not linearly correlated with NH4+ oxidizing activity, implying low counting efficiency, heterotrophic nitrification, or rate-limiting substrate NH4+ level. In a separate study, a soilless potting medium was inoculated with pure cultures of either Nitrosomonas europaea or Nitrobacter agilis. Rates of NH4+ and NO2- oxidation increased, respectively, as inoculum volume increased. Inoculation with nitrifying bacteria may help in the overall management of N in the rhizosphere and be feasible alternatives for the prevention of either NH4+ or NO2- phytotoxicity with fertilizers containing urea or NH4+.
Genetic Diversity Based on Randomly Amplified Polymorphic DNA (RAPD) and Its Relationship with the Performance of Diploid Potato Hybrids
Authors: Paz M.M. , Veilleux R.E.
Published: January 2019

RAPD analysis was conducted on in vitro plantlets of Solanum phureja Juz. & Buk. monoploids and diploid heterozygous pollinators. Among 60 decamer primers screened, 11 did not show polymorphism while some primers produced complex banding patterns or faint bands that were difficult to score. Genetic distance estimates were based on 151 polymorphic RAPD markers of 208 bands scored using 33 primers. Simple matching and Jaccard coefficients were calculated to estimate genetic similarity (GS). Genetic distance (GD=1-GS) among genotypes ranged from 0.0 to 0.664. Cluster analysis yielded groups of genotypes that were consistent with known genomic compositions or genetic relationships inferred from their pedigree. Field evaluation of 14 F1 families resulting from five S. phureja doubled monoploids (DMs) crossed to three heterozygous pollinators (IDs) revealed significant differences in total tuber number, total tuber yield, average tuber mass, and vigor. Total tuber yield per family ranged from 174 to 404 g per plant and was significantly lower than the control `Kennebec'. The general combining ability of DM BARD 13-14/202 was superior to other DM parents. Specific combining ability was observed in progeny of AD2-4/3s.8 H ID 4. Among male parents, ID 8 performed better than ID 4 or ID 5. Using simple matching, the largest parental genetic distance was always associated with the highest total tuber yield among progenies of DM parents. A similar trend was obtained using Jaccard coefficients. Based on our results, RAPD markers may facilitate the identification of diverse parents to maximize the expression of heterosis in S. phureja hybrids.
Ripening-associated Biochemical Traits of Cantaloupe Charentais Melons Expressing an Antisense ACC Oxidase Transgene
Authors: Guis Monique , Botondi Rinaldo , Ben-Amor Mohamed , Ayub Ricardo , Bouzayen Mondher , Pech Jean-Claude , Latché Alain
Published: January 2019

Transgenic Cantaloupe Charentais melons (Cucumis melo var. cantalupensis Naud. `Védrantais') exhibiting strong inhibition of ethylene production were used as a model to discriminate between ethylene-regulated and ethylene-independent ripening pathways. Compared to wild-type fruit, transgenic fruit did not undergo significant yellowing of the rind and softening of the flesh. However, these effects were completely reversed by treating transgenic fruit with 50 μL·L-1 exogenous ethylene. Pigmentation of the flesh occurred early before the onset of the climacteric and was thus unaffected by ethylene inhibition in transgenic fruit. Total soluble solids accumulated at the same rate in both types of fruit until 38 days after pollination when wild-type fruit abscissed. However, as ethylene-inhibited fruit failed to develop a peduncular abscission zone, they remained attached to the plant and accumulated higher amounts of sugars, mainly sucrose. Harvesting transgenic fruit resulted in a small but significant increase of internal ethylene associated with softening of the flesh.
Effect of Antibiotics and Exposure to an Acidified Medium on the Elimination of Agrobacterium tumefaciens from Apple Leaf Explants and on Shoot Regeneration
Authors: Hammerschlag Freddi A. , Zimmerman Richard H. , Yadava Umedi L. , Hunsucker Sally , Gercheva Petya
Published: January 2019

A range of antibiotics and short-term exposure to an acidified (pH 3.0) medium were evaluated for their effects on eliminating Agrobacterium tumefaciens, supervirulent strain EHA101 (pEHA101/pGT100), from leaf explants of `Royal Gala' apple (Malus ×domestica Borkh.) and on shoot regeneration. Exposure of leaf explants to regeneration and elongation media containing 100 μg·mL-1 concentrations of the antibiotics carbenicillin (crb), cefotaxime (cef), and cefoxitin [=mefoxin (mef)], singly or in combination for 52 days did not eliminate A. tumefaciens from the explants. The percentage of regeneration on crb, cef, and mef was 97%, 11%, and 50%, respectively, compared to 67% for the controls. Short-term (1- to 18-hour) vacuum infiltration with 500 μg·mL-1 of any of the above antibiotics did not inhibit regeneration and failed to eliminate A. tumefaciens from leaf explants. Cef (2000 μg·mL-1) did not inhibit the percentage of regeneration and was more effective than crb or mef in preventing growth of A. tumefaciens when vacuum infiltrated into apple leaf explants for 30 minutes. Further experiments demonstrated that the incidence of A. tumefaciens contamination could be reduced to 28% without negatively impacting shoot regeneration by using a 1-hour vacuum infiltration with an acidified medium, an 18-hour vacuum infiltration with cef (5000 μg·mL-1), and a 52-day incubation on regeneration and elongation media containing 100 μg·mL-1 each of mef and crb. Kan resistant, GUS (β-glucuronidase) positive, putative transformants without A. tumefaciens were generated by adding kan (10 μg·mL-1) to the regeneration and elongation media.
Engineering Genetic Resistance against Insects in Japanese Persimmon Using the cryIA(c) Gene of Bacillus thuringiensis
Authors: Tao Ryutaro , Dandekar Abhaya M. , Uratsu Sandra L. , Vail Patrick V. , Tebbets J. Steven
Published: January 2019

Japanese persimmon (Diospyros kaki L. `Jiro') was transformed using a disarmed strain of Agrobacterium tumefaciens, EHA101, carrying the binary plasmid vector, pDU92.710. The T-DNA region of pDU92.710 contained the kanamycin resistance gene (nptII), the β-glucuronidase gene (uidA), and a synthetic reconstruct of cryIA(c) encoding the insecticidal crystal protein fragment of Bacillus thuringiensis subsp. kurstaki HD-73. Leaf discs made from leaves of shoot cultures were cocultivated with Agrobacterium and cultured on a callus-induction medium containing kanamycin and cefotaxime. Among 720 infected leaf discs, 17 putative transformed callus lines showing kanamycin resistance were obtained after 8 weeks of culture. When these were cultured on a regeneration medium containing kanamycin, 15 formed adventitious buds. Of the 15 shoot lines, 11 grew well on a shoot-proliferation medium containing kanamycin, while 4 lines did not grow well. Of the 11 shoot lines, 10 showed GUS activities by fluorometric assay and were subjected to polymerase chain reaction (PCR) and Southern analyses. Except for two lines, all results were consistent with a stable integration of T-DNA into the persimmon genome. The production of CryIA(c) protein in transformed shoot lines was confirmed with Western analysis using anti-CryIA(c) serum. Insect bioassays were conducted with 10 lines showing GUS activity. Many of these lines showed high significant mortality of the test insects, Plodia interpunctella Hüber and Monema flavescens Walker, when compared to nontransformed controls.
Outcrossing Rate, Yield, and Selective Fruit Abscission in `Ettinger' and `Ardith' Avocado Plots
Authors: Degani C. , El-Batsri R. , Gazit S.
Published: January 2019

The reciprocal effect of two avocado (Persea americana Mill.) cultivars—Ardith and Ettinger—on outcrossing rate and yield was studied in several orchards in Israel. Multilocus estimates of outcrossing rates were made using the isozyme loci Mdh-1 (malate dehydrogenase) and Aat-1 (aspartate aminotransferase) for `Ettinger' progeny and Lap-2 (leucine aminopeptidase), Pgm-1 (phosphoglucomutase) and Tpi-1 (triosephosphate isomerase) for `Ardith' progeny. When the two cultivars were in close proximity, estimated yields ranged from 10 to 20 t·ha-1 and outcrossing rates ranged from 0.71 to 0.89 and from 0.87 to 0.90 for `Ettinger' and `Ardith', respectively. The effect of `Ettinger' as a pollenizer was not restricted to adjacent `Ardith' trees; it also reached more distant `Ardith' trees. Thus, outcrossing rate in `Ardith' was 0.82 at a distance of 30 m from `Ettinger' in one orchard and 0.91 at a distance of 36 m in another orchard. These results confirm previous observations that `Ettinger' is a highly potent pollenizer. Outcrossing rates in `Ardith' and `Ettinger' were found to increase from the young fruitlet stage to that of mature fruit. These findings provide evidence for selective abscission of selfed fruitlets. In addition, parentage analysis of abscised versus retained `Ardith' fruit showed that `Ardith' selfed fruit abscised at a much higher rate than outcrossed ones. The survival advantage of outcrossed fruit is probably related to the fact that selfed progeny have less-vigorous embryos than outcrossed progeny due to inbreeding depression.
Autopolyploidy versus Allopolyploidy and Low-density Randomly Amplified Polymorphic DNA Linkage Maps of Sweetpotato
Authors: Ukoskit Kittipat , Thompson Paul G.
Published: January 2019

Low-density randomly amplified polymorphic DNA (RAPD) markers of sweetpotato [Ipomoea batatus (L.) Lam.; 2n = 6x = 90] were constructed from 76 pseudotestcross progenies obtained from `Vardaman' × `Regal'. Of 460 primers, 84 generating 196 well-resolved repeatable markers were selected for genetic analysis. `Vardaman' and `Regal' testcross progenies were analyzed for segregation and linkages of RAPD markers. Type of polyploidy, autopolyploidy, or allopolyploidy is uncertain in sweetpotato and was examined in this study using the ratio of nonsimplex to simplex RAPD markers and the ratio of simplex RAPD marker pairs linked in repulsion to coupling. Both measures indicated autopolyploidy. Low-density RAPD linkage maps of `Vardaman' and `Regal' were constructed from simplex RAPD marker linkage analysis. Duplex and triplex markers were then mapped manually into the simplex marker map. Homologous linkage groups were identified using nonsimplex RAPD markers and three homologous groups were found in each of the parent maps. Use of nonsimplex markers increased mapping efficiency. The `Vardaman' map had a predicted coverage of 10.5% at a 25-cM interval of the genome size of 5024 cM. In `Regal', genome coverage was estimated to be 5.6% at a 25-cM interval of the genome size of 6560 cM. Therefore, average chromosome length was ≈56 to 73 cM.
Anatomical and Histochemical Effects of Feeding by Citrus Leafminer Larvae (Phyllocnistis citrella Stainton) in Citrus Leaves
Authors: Achor D.S. , Browning H. , Albrigo L.G.
Published: January 2019

Young expanding leaves of `Ambersweet' [Citrus reticulata Blanco × C. paradisi Macf. × C. reticulata) × C. sinensis (L) Osb.] with feeding injury by third larval stage of citrus leafminer (Phyllocnistis citrella) were examined by light and electron microscopy for extent of injury and tissue recovery over time. Results confirmed that injury is confined to the epidermal layer, leaving a thin covering over the mine tunnel that consisted of the cuticle and outer cell wall. Wound recovery consisted of two possible responses: the production of callus tissue or the formation of wound periderm. The production of callus tissue developed within 3 days of injury when the uninjured palisade or spongy parenchyma below the injured epidermis produced callus tissue through periclinal or diagonal cell divisions. After 1 month, the entire epidermis was replaced by callus tissue. In the absence of secondary microbial invasion, this callus tissue developed a thick cuticle, followed by development of a covering of platelet wax after 4 months. Alternatively, wound periderm formed if the outer cuticular covering was torn before the cuticle had developed sufficiently to prevent the exposed cells from being desiccated or invaded by fungi, bacteria, or other insects. The wound periderm consisted of a lignified layer of collapsed callus cells, a suberized phellem layer, and a multilayered phelloderm-phellogen. Since there were always cellular collapse or fungi and bacteria associated with wound periderm formation, it was determined to be a secondary effect, not a direct effect of leafminer feeding.
Seasonal Changes in Total Nonstructural Carbohydrates within Branches and Roots of Naturally “Off” and “On” `Kerman' Pistachio Trees
Authors: Nzima Muntubani D.S. , Martin George C. , Nishijima Chic
Published: January 2019

The objective of this investigation was to determine the dynamics of carbohydrate use as revealed by soluble sugar and starch concentration in leaves, inflorescence buds, rachises, nuts, current and 1-year-old wood, and primary and tertiary scaffold branches and roots (≤10 mm in diameter) of alternate-bearing `Kerman' pistachio (Pistachia vera L.) trees that were in their natural bearing cycles. Two hypotheses were tested. First, carbohydrate concentration is greater early in the growing season in organs examined from heavily cropping (“on”) than light cropping (“off”) trees. This hypothesis was affirmed as judged by soluble sugar and starch concentration in leaves, inflorescence buds, rachises, nuts, current and 1-year-old wood, and primary and tertiary branches and roots of “on” compared to “off” trees. Second, carbohydrate concentration remains high in “on” tree organs as the first wave of inflorescence bud and nut abscission occurs early in the growing season. This hypothesis was also affirmed. In fact, soluble sugars and starch remained high in “on” trees through full bloom FB + 60 days (FB + 60) as inflorescence bud and nut abscission occurred. In the persisting “on” tree inflorescence buds, sharp decreases in soluble sugars and starch were evident by the final sample date when “off” tree inflorescence buds contained a 13 times greater concentration of soluble sugars and starch than “on” tree buds. At that time, “off” tree inflorescence buds contained 50% more dry mass than “on” tree inflorescence buds. After FB + 60, “on” tree soluble sugars and starch declined in all organs as nut growth occurred. During the same time period, organs of “off” trees began to accumulate greater concentrations of soluble sugars and starch and exceeded concentrations measured in organs of “on” trees.
Postharvest Heat Treatment of Apples to Control San Jose Scale (Quadraspidiotus perniciosus Comstock) and Blue Mold (Penicillium expansum Link) and Maintain Fruit Firmness
Authors: Lurie Susan , Fallik Elazar , Klein Joshua D. , Kozar Frerenc , Kovacs Kornel
Published: January 2019

Postharvest heat treatments were applied to three apple (Malus domestica Borkh.) cultivars: `Anna', `Golden Delicious', and `Jonathan'. The temperatures ranged from 38 to 50 °C and from 5 to 96 hours. The temperatures of 50 °C for 5 or 10 hours and 46 °C for 10 hours controlled all developmental stages of San Jose scale on `Golden Delicious' and `Jonathan' fruit. Blue mold germination was prevented by 46, 42, and 38 °C after 28, 34, and 42 hours, respectively. The time needed to control the fungus was longer than that required to kill the insect. Apples were damaged by a 50 °C treatment but could withstand at least 12 hours at 46 °C and at least 24 hours at 42 °C. At 38 °C no damage was found on preclimacteric apples even after 96 hours, but if postclimacteric fruit were heated at 38 °C heat damage occurred. The treatments that did not cause damage maintained the fruit firmness during post storage ripening. The results are discussed in the context of developing integrated postharvest heat treatments.
Effect of Carbon Dioxide on Anthocyanins, Phenylalanine Ammonia Lyase and Glucosyltransferase in the Arils of Stored Pomegranates
Authors: Holcroft Deirdre M. , Gil Maria I. , Kader Adel A.
Published: January 2019

`Wonderful' Pomegranates (Punica granatum L.) were placed in jars ventilated continuously with air or air enriched with 10 or 20 kPa CO2 at 10 °C for 6 weeks. Samples were taken initially and after 1, 2, 4, and 6 weeks, and postharvest quality attributes were measured. The arils of the pomegranates stored in air were deeper red than the initial controls and than those stored in CO2-enriched atmospheres. This increased color was associated with increased anthocyanin concentration. Arils from fruit stored in air enriched with 10 kPa CO2 had a lower anthocyanin concentration than air-stored fruit, and atmospheres enriched with 20 kPa CO2 had even lower levels, possibly from suppressed anthocyanin biosynthesis. Anthocyanin concentration correlated well with the activity of phenylalanine ammonia lyase but not with glucosyltransferase activity. Moderate CO2 atmospheres (10 kPa) prolong the storage life and maintain quality of pomegranates, including adequate red color intensity of the arils.
Effect of Fall Irrigation Level in `Mauritius' and `Floridian' Lychee on Soil and Plant Water Status, Flowering Intensity, and Yield
Authors: Stern R.A. , Meron M. , Naor A. , Wallach R. , Bravdo B. , Gazit S.
Published: January 2019

The effect of fall irrigation level in `Mauritius' and `Floridian' lychee (Litchi chinensis Sonn.) on soil and plant water status, flowering intensity, and yield the following year was studied in a field during 2 consecutive years. At the end of the second vegetative flush after harvest (1 Oct. 1994 and 10 Oct. 1995), four irrigation treatments were initiated: 0.5, 0.25, 0.125, and 0 Class A pan evaporation coefficients designated 100%, 50%, 25%, and 0%. The three lower irrigation levels effectively stopped shoot growth, suggesting the 50% treatment to be the threshold for shoot growth cessation in both years. For both years, flowering intensity and yield in the 100% treatment were lower than those following the other three treatments. Soil and plant water-stress indicators responded to the water-stress irrigation treatments. However soil water-potential values were highly variable relative to plant water potentials. Stem water potential differed more markedly between treatments than leaf water potential. Midday stem water potential appeared to be the best water-stress indicator for irrigation control. Midday stem water potential in both years was correlated with midday vapor-pressure deficit, suggesting that the threshold for irrigation control should take into account evaporative demand.
Patterns of Saskatoon (Amelanchier alnifolia Nutt.) Fruit and Seed Growth
Authors: McGarry Roisin , Ozga Jocelyn A. , Reinecke Dennis M.
Published: January 2019

Saskatoon fruit are an emerging horticultural crop across the Canadian prairies. As fruit size varies greatly among cultivars, knowledge of fruit growth patterns and factors that affect fruit size can be used to establish breeding trials and develop orchard management strategies that could enhance the production of this crop. In this study, we 1) determined fruit and seed growth patterns among large-, medium-, and small-fruited cultivars of saskatoon using growing degree days to standardize time to crop development and 2) assessed the role of seed number on fruit size. Fruit growth patterns of four cultivars (Thiessen, Northline, Regent, and Smoky) were determined from weekly measurements of fresh and dry fruit mass during two consecutive seasons. These growth patterns exhibited three phases. The largest fruit at maturity were from `Thiessen', followed by `Northline', `Smoky', and `Regent', in descending order. Pedicel cross-sectional areas 1 week before maturity correlated linearly with increasing fresh and dry fruit mass and seed number per fruit. At maturity, seed number per fruit correlated linearly with fresh and dry fruit mass. `Thiessen' contained significantly more seeds per fruit (4.6) than `Northline' (3.7), `Smoky' (3.2), and `Regent' (3.2). The results of this research suggest potential areas for orchard management improvement and future research directions for saskatoon crop improvement.
pH Affects 1H-indole-3-butyric Acid Uptake but not Metabolism during the Initiation Phase of Adventitious Root Induction in Apple Microcuttings
Authors: Harbage James F. , Stimart Dennis P. , Auer Carol
Published: January 2019

The influence of root initiation medium pH on root formation was investigated in relation to uptake and metabolism of applied IBA in microcuttings of Malus ×domestica Borkh. `Gala' and `Triple Red Delicious'. Root formation and uptake of H3-IBA were related inversely to root initiation medium pH. Maximum root count (10.3 roots) and IBA uptake were observed at pH 4.0. Regardless of pH, overall root count of `Gala' was higher (13.5 roots) than `Triple Red Delicious' (4 roots). Uptake of IBA was highest at pH 4.0 for `Gala' (1.7% uptake) and at pH 4 and 5 for `Triple Red Delicious' (0.75% uptake). Metabolism of IBA was the same regardless of root initiation medium pH or cultivar examined. One-half of the IBA taken up was converted to a compound that coeluted with IBAsp during high-performance liquid chromatography. Apparently, pH regulates root formation by affecting IBA uptake but not metabolism. The level of auxin in tissue appeared unrelated to root formation between genotypes. Chemical names used: 1H-indole-3-butyric acid (IBA); 5-H3-indole-3-butyric acid (H3-IBA); indole-3-butrylaspartic acid (IBAsp).
Doubled-haploid Broccoli Production Using Anther Culture: Effect of Anther Source and Seed Set Characteristics of Derived Lines
Authors: Farnham Mark W.
Published: January 2019

Using anther culture to generate doubled-haploid (DH) homozygous lines for use as parents in F1 hybrid crosses has become a common practice in breeding broccoli (Brassica oleracea L. Italica Group). During anther culture and subsequent embryogenesis and plant regeneration, polyploidization of microspore-derived embryos may not occur or it may occur accompanied by a doubling, tripling, quadrupling, octupling, or irregular polyploidization of the genome. Thus regenerants from the process can be haploids, diploids, triploids, tetraploids, octaploids, or aneuploids. The objectives of this research were to 1) conduct repeat cycles of broccoli anther culture using a group of F1 hybrids as anther donors and develop populations of regenerants; 2) analyze resulting populations using DNA flow cytometry and determine the influence of F1 source on frequency of different ploidy levels among regenerants; and 3) compare seed set in broccoli inbreds developed in a traditional selfing program compared to seed set in DH broccoli derived from anther culture. In two cycles (1994 and 1995) of anther culture, anther-derived populations of regenerants were developed using the F1 hybrids `Marathon', `Everest', `High Sierra', and `Futura' as sources of anthers. In 1994, `Everest', `High Sierra', and `Futura' yielded populations that included 2% to 7% haploids, 53% to 56% diploids, 32% to 38% tetraploids, and 5% to 6% other types. `Marathon'-derived regenerants were 5% haploid, 78% diploid, 15% tetraploid, and 2% other, showing significantly more diploids. In 1995, `Marathon' regenerants again included significantly more diploids and fewer tetraploids than those derived from other F1 sources, confirming that the genotype of the anther source affects the frequency of a particular ploidy level among regenerants derived from culture. In manual self-pollinations of 1994 regenerants, only diploids and rare tetraploids set seed. When plants that set no seed were discounted, seed production following manual self pollinations of 1995 regenerants was not significantly different from that of traditional inbreds derived from the same F1 sources.