bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlations of Crop Load and Return Bloom with Root and Shoot Concentrations of Potassium, Nitrogen, and Nonstructural Carbohydrates in Pecan
Authors: Smith Michael W. , Rohla Charles T. , Maness Niels O.
Published: January 2019

The current theory of pecan [Carya illinoinensis (Wangenh.) C. Koch] alternate bearing is the “growth regulator–carbohydrate theory” in which flowering is first controlled by growth regulators produced by fruit and leaves, and then by the size of the carbohydrate pool near budbreak. Lack of nitrogen (N) reserves has also been proposed to be limiting after large crops, thus reducing return bloom. Annual production was determined for 12 individual trees for 3 years. Return bloom was monitored on four previous-season shoot types: 1) vegetative shoots, 2) bearing terminal shoots without a second growth flush, 3) bearing lateral shoots without a second growth flush, and 4) bearing shoots that were primarily in the terminal position with a second growth flush. Nonstructural carbohydrates, organically bound N, and potassium (K) concentrations were determined in roots and shoots. Regression analysis was used to determine the effect of yield on subsequent nonstructural carbohydrates, N, and K in the roots and shoots, and their postyield concentrations on subsequent flowering. Alternate bearing was evident because there were reductions of 18%, 16%, and 18% in the percentage of current season shoots flowering for every 10 kg/tree production increase in the previous season's yield in 2002, 2003, and 2004 respectively. Flower production in 2002 decreased by 2.6 flowers/1-year-old branch and 1.6 flowers/1-year-old branch in 2003 for each 10 kg/tree increase in production. The third year of the study, neither previous season shoot type nor yield affected subsequent flower production. The previous year's shoot type did not affect the percentage of current season shoots flowering; however, the previous year's shoots that had a second growth flush produced more flowers the following year than the other shoot types. Results suggested that crop load was not related to nonstructural carbohydrates, N, or K in the roots and shoots during January in these well-managed trees. Stored nonstructural carbohydrates, N, and K were also not related to return bloom. These data suggest that the current “growth regulator–carbohydrate theory” may not be valid in these well-managed trees. Nonstructural carbohydrates, K, and organically bound N do not appear to be critical factors regulating flowering.
Assessment of Genetic Diversity and Relationships Among Caladium Cultivars and Species Using Molecular Markers
Authors: Deng Zhanao , Goktepe Fahrettin , Harbaugh Brent K. , Hu Jinguo
Published: January 2019

Caladium (Caladium ×hortulanum Birdsey) is an important aroid widely used in the ornamental plant industry. Concerns have been raised about possible loss of genetic diversity due to a drastic decline in the number of cultivars in the last century. This study assessed genetic diversity and relationships among caladium cultivars and species accessions. Forty-five major cultivars and 14 species accessions were analyzed based on 297 DNA fragments produced by the target-region amplification polymorphism marker system. A low level of diversity (44.4% polymorphism) was exhibited in cultivars, while a high level of diversity (96.8% polymorphism) was present among seven accessions of Caladium bicolor (Aiton) Vent., Caladium marmoratum Mathieu, Caladium picturatum C. Koch, and Caladium schomburgkii Schott. A small percentage (7.6%) of DNA fragments was present in cultivars but absent in the seven species accessions, while a high percentage (32.2%) of DNA fragments was present in the seven species accessions but absent in cultivars. Cultivars shared a higher level of similarity at the molecular level with an average Jaccard coefficient at 0.802, formed a large group in cluster analysis, and concentrated in the scatter plot from a principal-coordinate analysis. Two accessions of C. bicolor and C. schomburgkii were very similar to cultivars with Jaccard similarity coefficients from 0.531 to 0.771, while the rest of the species accessions had small similarity coefficients with cultivars (0.060 to 0.386). Caladium steudnirifolium Engler and Caladium lindenii (André) Madison were very dissimilar to C. bicolor, C. marmoratum, C. picturatum, and C. schomburgkii, with Jaccard similarity coefficients from 0.149 to 0.237 (C. steudnirifolium) and from 0.060 to 0.118 (C. lindenii). There is a limited amount of molecular diversity in caladium cultivars, but the great repertoire of unique genes in species accessions could be used to enhance the diversity in future cultivars and reduce potential genetic vulnerability.
Antioxidant Activity and Phenolic Composition in ‘Beauregard’ Sweetpotato Are Affected by Root Size and Leaf Age
Authors: Padda Malkeet S. , Picha D.H.
Published: January 2019

Phenolic acids are considered important antioxidants that may help to prevent many human chronic diseases. The antioxidant activity and phenolic content of sweetpotato [Ipomoea batatas (L.) Lam.] roots and leaves of different sizes and ages, respectively, were quantified. Small roots (≈4 g root weight) had a higher antioxidant activity and phenolic content compared with full-sized marketable roots (≈300 g root weight). Phenolic content in marketable roots was significantly higher in the cortex tissue than in the internal pith tissue. The highest total phenolic content [chlorogenic acid equivalents (10.3 mg·g−1 dry weight)] and antioxidant activity [Trolox equivalents (9.7 mg·g−1 dry weight)] was found in cortex tissue of small-sized roots. Sweetpotato leaves had a significantly higher phenolic content and antioxidant activity than roots. Young, immature unfolded leaves had the highest total phenolic content (88.5 mg·g−1 dry weight) and antioxidant activity (99.6 mg·g−1 dry weight). Chlorogenic acid was the major phenolic acid in root and leaf tissues with the exception of young immature leaves in which the predominant phenolic acid was 3,5-dicaffeoylquinic acid. The results suggest that small-sized roots, which are typically discarded in the field, and young immature leaves may be concentrated sources of phenolic antioxidants.
The Chilean Strawberry [Fragaria chiloensis (L.) Duch.]: Genetic Diversity and Structure
Authors: Carrasco Basilio , Garcés Marcelo , Rojas Pamela , Saud Guillermo , Herrera Raúl , Retamales Jorge B. , Caligari Peter D.S.
Published: January 2019

The chilean strawberry displays high fruit quality and tolerance to abiotic and biotic factors. Additionally, this species has a rich cultural history going back for at least several thousand years in association with aboriginal people activities and continues at a reduced level today. After its introduction to Europe during the 18th century, it formed an interspecific hybrid to become the maternal species of the commercial strawberry, Fragaria ×ananassa Duch. The objectives of the current investigation were to determine the level and patterns of partitioning of intersimple sequence repeat (ISSR) diversity. ISSR markers were used to assess the genetic diversity in 216 accessions of F. chiloensis, which represented the two botanical forms present in Chile [F. chiloensis ssp. chiloensis f. chiloensis and F. chiloensis ssp. chiloensis f. patagonica (L.) Duch.]. Our results showed high genetic diversity at the species level [polymorphic ISSR loci (P) = 89.6%, gene diversity (h) = 0.24 ± 0.17, Shannon's index (S) = 0.37 ± 0.24] and a lower genetic diversity in f. chiloensis than f. patagonica. The analysis of molecular variance (AMOVA) showed a moderate genetic differentiation among accessions (φst = 14.9%). No geographic patterns for ISSR diversity were observed. AMOVA, structure, and discriminant analysis indicated that accessions tend to group by botanical form. The impact of domestication on the genetic structure of chilean strawberry and its application to breeding and conservation are discussed.
Identification of Resistance Gene Analogs and Verticillium Wilt Resistance-like Sequences in Mentha longifolia
Authors: Vining Kelly J. , Zhang Q , Smith C.A. , Davis T.M.
Published: January 2019

Resistance gene analog (RGA) sequences were obtained from four Mentha longifolia (L.) Huds. accessions using degenerate polymerase chain reaction (PCR) primers targeting the conserved nucleotide binding site domain found in many plant disease resistance genes. Seven distinct RGA families were identified. All M. longifolia RGAs showed similarity to sequences of the non-toll-interleukin 1 receptor R gene class. In addition, degenerate PCR primers based on the tomato (Solanum lycopersicum L.) verticillium wilt resistance (Ve) genes were used to PCR-amplify a 445-base pair (bp) Ve-like sequence from M. longifolia that had ≈57% predicted amino acid identity with Ve. Mint-specific primers based on the original mint Ve sequence were used to obtain mint-specific Ve sequences from four M. longifolia accessions and from peppermint (Mentha ×piperita L.) cultivar ‘Black Mitcham’ that had 95% to 100% predicted amino acid identity to the original mint Ve sequence. Inverse PCR was then used to obtain flanking mint Ve sequence from one M. longifolia accession extending the mint Ve sequence to 1077 bp. This is the first report of RGA sequences in the Lamiaceae and the first report of Ve-like sequences obtained with degenerate PCR primers.
Expression of a Rice Chlorophyll a/b Binding Protein Promoter in Sweetpotato
Authors: Song Guo-qing , Honda Hideo , Yamaguchi Ken-ichi
Published: January 2019

Leaves are usually the target tissue for expressing transgenes conferring resistances to herbicides, pests, and diseases. To achieve leaf-specific expression, a light-harvest chlorophyll a/b binding protein (CAB) of photosystem-II (CAB2) promoter (CAB2-p) from rice (Oryza sativa L.) and the cauliflower mosaic virus 35S promoter were fused to the β-glucuronidase (GUS) reporter and subsequently evaluated in transgenic sweetpotato [Ipomoea batatas L. (Lam.)]. The 35S promoter-directed GUS activities varied from 46.0 to 61.2 nmol 4-methyl-umbelliferyl-β-D-glucuronide (4-MU) per minute per milligram of protein in leaf, stem, primary, and storage roots. In contrast, the CAB2-p directed an uneven distribution of GUS activities (4-MU at 1.1 to 12.6 nmol·min−1·mg−1 protein); GUS activity in mature leaves was ≈12-fold as high as that in storage roots. In addition, GUS assay in leaf tissues revealed that CAB2-p enabled a developmentally controlled and light-regulated GUS expression. These results indicate that the rice CAB2-p could be used to drive leaf-specific expression of linked genes in sweetpotato.
Repetition of Hydrogen Peroxide Treatment Induces a Chilling Tolerance Comparable to Cold Acclimation in Mung Bean
Authors: Hung Shu Hsien , Wang Chun Chi , Ivanov Sergei Veselinov , Alexieva Vera , Yu Chih Wen
Published: January 2019

Mung bean seedlings (Vigna radiata L.) of the cultivar Tainan No. 5 (a chilling-sensitive cultivar) pretreated with multiple sprays of 200 mm H2O2 showed a tolerance to chilling at 4 °C for 36 h, measured by electrolyte leakage, that was greater than that induced by a single treatment and similar to that induced by cold-acclimation at 10 °C for 48 h. Two H2O2 treatments at an interval of 3 h gave the optimum chilling tolerance. Tolerance induced by H2O2 could be distinguished from that induced by acclimation at 10 °C according to length at 4 °C and corresponding electrolyte leakage. Chilling tolerance induced by H2O2 depended on accumulation of glutathione (GSH), which could be significantly reversed by pretreatment with buthionine sulfoximine (BSO). In contrast, tolerance induced by incubation at 10 °C for 48 h in light was neither accompanied by accumulation of GSH nor reversed by BSO, suggesting that there are at least two independent mechanisms of developing chilling tolerance. Chilling tolerance of both cold-acclimated and H2O2-treated seedlings was decreased by ethyleneglycol-bis(aminoethylether)-N,N′-tetraacetic acid (EGTA) but not by ruthenium red, indicating that the influx of Ca2+ from extracellular, but not intracellular, pools is an important signal in the induction of tolerance. In confirmation, sprays of Ca2+ could be substituted for H2O2.
Evaluation of Watermelon and Related Species for Resistance to Race 1W Powdery Mildew
Authors: Davis Angela R. , Levi Amnon , Tetteh Antonia , Wehner Todd , Russo Vincent , Pitrat Michel
Published: January 2019

Powdery mildew [Podosphaera xanthii (Castagne) Braun & Shishkoff (syn. Sphaerotheca fuliginea auct. p.p.)] is now a common disease on watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] in the United States. In this study, the entire available U.S. Plant Introduction collection of Citrullus Schrad. ex Eckl. & Zeyh. species was evaluated for resistance to P. xanthii race 1W. The collection consists of four Citrullus species and one Praecitrullus Pangalo species [C. lanatus var. citroides (L.H. Bailey) Mansf., C. colocynthis (L.) Schrad., C. rehmii De Winter, and P. fistulosus (Stocks) Pangalo]. Wild-type accessions tended to be more resistant more often than the cultivated species, C. lanatus var. lanatus. None were immune, eight of the 1573 accessions exhibited high levels of resistance, and another 86 demonstrated intermediate resistance. Stem and leaf disease severity were weakly correlated (r
2 = 0.64, P = 0.001). The majority of accessions having resistance were collected in Zimbabwe. Resistance was found in four species.
Variation in Saltgrass Growth and Time of Fall Dormancy Related to Geographical and Climatic Factors
Authors: Rukavina Hrvoje , Hughes Harrison , Johnson Randy
Published: January 2019

Development of a new turfgrass cultivar requires an evaluation of numerous traits as well as an understanding of environmental factors influencing those traits. Growth or ability to fill in gaps and time of fall dormancy (fall color retention) that indicates cold hardiness are important traits for turfgrasses. This study was initiated to characterize variation in saltgrass [Distichlis spicata L. (Greene)] growth and time of fall dormancy related to climatic and geographical factors at the source location (geographical location of clone origin). Growth traits and time of fall dormancy were measured on 52 saltgrass clones collected from 41 locations and established at one location (common garden) in Fort Collins, CO. Principal component analysis on the morphological traits extracted the first principal component that explained 78% of the variability. The first principal component and time of fall dormancy were related to climatic and geographical factors at the source locations. Variation in growth traits was related to seasonal climatic variables of summer drying and fall cooling that explained ≈50% of variability in morphological traits. Variation in time of fall dormancy was related to longitude of clone origin and minimum winter temperature. These two variables explained ≈60% of the total variability in time of fall dormancy. Information obtained in this study may help breeders identify the best environments for specific traits and suggests that cold tolerance could be a problem for some clones from western sources if established too far east.
Ratio of Myc and Myb Transcription Factors Regulates Anthocyanin Production in Orchid Flowers
Authors: Ma Hongmei , Pooler Margaret , Griesbach Robert
Published: January 2019

Many studies have examined anthocyanin gene expression in colorless tissues by introducing anthocyanin regulatory genes of the MYC/R and MYB/C1 families. Expression of the two regulatory genes under the control of a strong promoter generally results in high anthocyanin accumulation. However, such approaches usually have a negative effect on growth and development of the recovered plants. In this study the author used two promoters of different strengths—a weak (Solanum tuberosum L. polyubiquitin Ubi3) and a strong (double 35S) promoter—and generated two sets of expression constructs with the Zea mays L. anthocyanin regulatory genes MycLc
and MybC1
. A transient expression system was developed using biolistic bombardment of white Phalaenopsis amabilis (L.) Blume flowers, which the authors confirmed to be anthocyanin regulatory gene mutants. Transient expression of different combinations of the four constructs would generate three different MycLc
-to-MybC1
ratios (>1, 1, <1). The enhanced green florescent protein gene (EGFP) was cotransformed as an internal control with the two anthocyanin regulatory gene constructs. These results demonstrate that the ratio of the two transcription factors had a significant influence on the amount of anthocyanin produced. Anthocyanin accumulation occurred only when MybC1
was under the control of the 35S promoter, regardless of whether MycLC
was driven by the 35S or Ubi3 promoter.
Diallel Analysis of Fruit Water Absorption in Tomato, a Contributing Factor in Postharvest Decays
Authors: Smith S.M. , Scott J.W. , Bartz J.A. , Sargent S.A.
Published: January 2019

Harvested tomato (Solanum lycopersicum L.) fruit can absorb water via stem scar tissues. Decay incidence {bacterial soft rot (Erwinia carotovora Jones), sour rot (Geotrichum candidum Link), bacterial sour rot [Leuconostoc mesenteroides (Tsenkovskii) van Tieghem ssp. mesenteroides], and certain species of Lactobacillus Beijerinck} has been positively linked with the degree of water absorption. Previous studies have shown that cultivars differ in their tendencies to take up water during a simulation of packinghouse handling procedures. The inheritance of water absorption tendency was examined in two seasons of tests where six inbred tomato lines were intercrossed to develop a complete diallel. Following harvest at the mature-green stage, fruit were weighed, submerged in water for 2 min, and then reweighed to determine water absorption. Parental lines were tested in three seasons. Two parental lines, Fla. 7776 and Fla. 7946, were always in the low-absorption grouping, and NC84173 also had relatively low absorption. Fla. 8059 and Fla. 7777 were always in the high-absorption group, and Fla. 8000 tended to have high absorption. General combining ability for the low water absorption fruit characteristic was significant for both seasons with a higher level of significance in the spring over the fall season (P ≤ 0.001 and P ≤ 0.05, respectively), while specific combining ability was not significant for either season. Thus, the low water absorption fruit characteristic appears to be additively inherited. Accurate knowledge of parental absorption should allow prediction of hybrid performance. None of the hybrids absorbed unexpected amounts of water over both seasons. Reciprocal effects were significant (P ≤ 0.05) for fall, and maternal effects were significant (P ≤ 0.05) in spring. However, there was no general trend in water absorption due to the direction of the cross and thus no clear evidence for cytoplasmic inheritance. Water absorption was much greater in spring than in fall. Based on previous observations, the greater absorption in spring was due to higher field temperatures. Because of such environmental effects, parent lines should be replicated and tested over several seasons to accurately assess their relative water absorption. Crosses between consistently low water absorption parents should provide low-absorption hybrids, but testing of hybrids before release is suggested to verify this.
Population Structure in Cultivated Lettuce and Its Impact on Association Mapping
Authors: Simko Ivan , Hu Jinguo
Published: January 2019

The association mapping technique is a useful tool for detecting markers linked to the genes underlying the variation of a trait among elite cultivars. To avoid false-positive results due to unrecognized population structure in the analyzed set of individuals, the subpopulations need to be identified. Fifty-four lettuce (Lactuca sativa L.) cultivars representing five horticultural types important in North America, together with six accessions from two wild species (Lactuca saligna L. and Lactuca serriola L.), were assayed for polymorphism with target region amplified polymorphism (TRAP) marker loci. The model-based clustering approach recognized three main subpopulations in cultivated lettuce that are well separated from wild species. Although the clustering based on molecular markers was generally in good agreement with horticultural types, some cultivars were classified differently or showed mixed origin. The effect of population structure on association mapping was tested on four traits with strong or weak correlation to the lettuce horticultural type and monogenic or polygenic mode of inheritance. Traits that were strongly correlated with lettuce types displayed many false-positive results when population structure was ignored, but the spurious associations disappeared when estimates of population structure or relative kinship (both based on molecular markers) were included in the statistical model. Using of horticultural types as covariate was not sufficient to control for spurious associations in the monogenic trait with strong correlation to lettuce types. The best approach to avoid spurious associations in lettuce association studies is to assess relatedness of accessions with molecular markers and to include this information into the statistical model.
Optimization of the Management of an Ex-situ Germplasm Bank in Common Fig with SSRs
Authors: Giraldo Esther , Lopez-Corrales Margarita , Hormaza Jose Ignacio
Published: January 2019

Common fig (Ficus carica L.) is an underused fruit crop cultivated in Mediterranean countries since antiquity. In this study, 20 simple sequence repeat (SSR) loci were used to characterize 209 fig accessions conserved in an ex-situ field germplasm collection. A total of 78 fragments were amplified with the 20 pairs of SSR primers, with an average of 3.9 alleles per locus and a size between 120 and 376 bp. The mean expected and observed heterozygosities were 0.36 and 0.41, respectively. The total value for the probability of identity was 6.8 × 10−4. The SSRs studied resulted in identification of 98 unique genotypes (46.86% of all accessions preserved in the bank), indicating a high number of synonyms. Unweighted pair group method with arithmetic averages (UPGMA) cluster analysis did not show clear groups based on geographic distance, although some specific groups related to fruit type were observed. The results confirm the usefulness of microsatellites for the identification of genetic diversity and potential value of germplasm management for fig.
Morphological and Histological Evaluations of In Vitro Regeneration in Elliottia racemosa Leaf Explants Induced on Media with Thidiazuron
Authors: Woo Seong Min , Wetzstein Hazel Y.
Published: January 2019

Georgia plume (Elliottia racemosa Muhlenb. ex. Elliott) is a rare deciduous shrub or small tree. It has sustained severe loss of habitat and its range is now restricted to a limited number of sites in the state of Georgia. Tissue culture protocols have been developed as a means to propagate and conserve this threatened species using leaf explants induced on medium supplemented with 10 μm thidiazuron (TDZ) and 5 μm indole-3-acetic acid (IAA). Bud-like clusters, elongated embryo-like protrusions, and shoot-like structures were produced from the leaf explants. Morphological and histological evaluations of cultures during induction and development were conducted using light microscopy of sectioned material and scanning electron micrography. Histology of explant tissues indicates that plant regeneration of Georgia plume occurs through a shoot organogenesis pathway that involves the formation of actively dividing meristematic regions originating in subepidermal cell layers that proliferate to form protuberances on the explant surface. Numerous well-formed shoot apical meristems with leaf primordia are produced, as well as fused shoot-like structures. Elongated, embryo-like structures had various degrees of shoot apex development. Evaluations of serial sections found that they lacked a defined root apex, and that basal portions were composed of parenchymatous files of cells with a broad point of attachment to the parent tissue. The lack of bipolarity and a root pole signifies that true somatic embryogenesis does not occur.
Genetic Diversity and Structure of Walnut Populations in Central and Southwestern China Revealed by Microsatellite Markers
Authors: Wang Hua , Pei Dong , Gu Rui-sheng , Wang Bao-qing
Published: January 2019

Molecular markers were used to study the genetic diversity, structure, and relationship of Juglans L. with nine populations (five from Juglans regia L. and four from Juglans sigillata Dode) in central and southwestern China. A moderate level of genetic diversity was observed at the population level with the number of effect alleles per locus (A
E) ranging from 1.75 to 3.35 (average 2.39) and the proportion of polymorphic loci (P) equaling 100.0%. The expected heterozygosity (H
E) within populations ranged from 0.389 to 0.687, and the average was 0.525. The proportion of genetic variation presented among populations accounted for 18.6% of the total genetic diversity. The overall gene flow (N
m) among populations equaled 1.10. The unweighted pair-group method using arithmetic averages (UPGMA) clustering and the Mantel test showed that genetic distances among the nine populations are in a good agreement with their geographic distribution, supporting the viewpoint that J. regia and J. sigillata belong to one species. We suggest that the central area of the southwestern mountain regions of China could be considered as a priority for walnut genetic resource conservation.
Comparison of Protein Profile and Peroxidases in Bush and Vine-type Tropical Pumpkin
Authors: Wu Tao , Cao Jiashu
Published: January 2019

Comparisons of total peroxidase activity and peroxidase isozymes as well as protein profiles among segregating, near-isogenic bush and vine phenotypes of pumpkin (Cucurbita moschata Duchesne) were investigated. Peroxidase activities of internode and leaf tissues of the bush plants were higher than those of respective vine tissues. Roots of bush plants, however, had a lower peroxidase activity than vine plants. In both bush and vine plants, peroxidase activities were lower in leaf tissues than in root and internode tissues. Electrophoretic comparisons revealed qualitative differences in peroxidase patterns in internodes between bush and vine plants. Moreover, qualitative differences between internode and root profiles were found between bush and vine plants in C. moschata. In conclusion, the results of this report revealed that a single gene conferring the bush phenotype in C. moschata might affect the relative expression of peroxidase activity, peroxidase isozymes, and protein profiles in leaf, internode, and root tissues.
Identification and Characterization of Anthocyanins by High-performance Liquid Chromatography–Electrospray Ionization–Mass Spectrometry in Herbaceous Peony Species
Authors: Jia Ni , Shu Qing-Yan , Wang Dan-Hua , Wang Liang-Sheng , Liu Zheng-An , Ren Hong-Xu , Xu Yan-Jun , Tian Dai-Ke , Tilt Kenneth Michael
Published: January 2019

Petal anthocyanins were systematically identified and characterized by high-performance liquid chromatography (HPLC)–electrospray ionization–mass spectrometry (MS) coupled with diode array detection among nine wild herbaceous peony (Paeonia L.) species (15 accessions). Individual anthocyanins were identified according to the HPLC retention time, elution order, MS fragmentation patterns, and by comparison with authentic standards and published data. Six main anthocyanins, including peonidin-3,5-di-O-glucoside, peonidin-3-O-glucoside-5-O-arabinoside (Pn3G5Ara), peonidin-3-O-glucoside, pelargonidin-3,5-di-O-glucoside, cyanidin-3,5-di-O-glucoside, and cyanidin-3-O-glucoside (Cy3G), were detected. In addition to the well-known major anthocyanins, some minor anthocyanins were identified in herbaceous peony species for the first time. Detection of the unique anthocyanins cyanidin-3-O-glucoside-5-O-galactoside and pelargonidin-3-O-glucoside-5-O-galactoside in both Paeonia anomala L. and P. anomala ssp. veitchii (Lynch) D.Y. Hong & K.Y. Pan indicated these two species should belong to the same taxon. Pn3G5Ara was found only in European wild species and subspecies suggesting different metabolic pathways between European and Chinese accessions. Anthocyanins conjugated with galactose and arabinose were observed in the genus Paeonia for the first time. The North American species, Paeonia tenuifolia L., had high Cy3G content in flower petals. This anthocyanin composition is distinct from the anthocyanin composition in Asian and European species and possibly is responsible for the vivid red coloration in flowers.
Quantitative Separation of the Bicarbonate from the Counter-cation Effect in Bean Plants
Authors: Valdez-Aguilar Luis A. , Reed David William , Cornell John A.
Published: January 2019

The effect of Rb+ and Na+ as counter-cations of HCO3
− was evaluated on bean (Phaseolus vulgaris L. cv. Poncho) plants using mixture experiment statistical methodology in a series of experiments set up in a controlled environment chamber. Mixture experiments using three components (Rb+, K+, and Na+) or two components (K+ and Na+) were conducted to delineate the toxicity of HCO3
− versus the counter-cation effect. The quantitative separation of the toxic effects was possible only when the individual stress had an additive effect when combined with the other stress. Potassium mixtures were used as reference for comparison with other mixtures because plants did not respond to K+, probably because it was included at a minimum concentration of 2.5 mm K+ or because it was supplied in the preestablishing solution. Rubidium caused a decrease in shoot dry weight (SDW), but SDW accumulation was even lower when HCO3
− was added to the Rb+ solutions. However, Rb+ was not included in follow-up experiments because the response of plants to Rb+ was very similar to that of Na+. The toxic effect of Na+ caused SDW to decrease at a rate of 3.7% per millimolar increase of Na+. However, the effect of HCO3
− was dependent on its concentration, because at 2.5 mm HCO3
−, the decrease in SDW was 12.7% per millimolar HCO3
−, whereas at 3.75, 5, and 5.65 mm, the decrease was 11.0%, 7.8%, and 10.7% per millimolar HCO3
−, respectively. At 7.5 mm HCO3
−, the decrease in SDW was 4.2% to 8.2% per millimolar increase in HCO3
−, respectively. The decreasing HCO3
− rate may be explained by the nonadditive effect between HCO3
− and Na+ at high alkalinity levels.
Comparison of Glucosinolate Profiles in Leaf and Seed Tissues of Different Brassica napus Crops
Authors: Velasco Pablo , Soengas Pilar , Vilar Marta , Cartea Maria Elena , del Rio Mercedes
Published: January 2019

The glucosinolate profile of leaves and seeds of 33 Brassica napus L. crops, including leafy crops, forage, rutabaga, and oilseed crops, was compared by high-performance liquid chromatography to investigate the relation between the consumable product of each crop and the glucosinolate profile. Glucosinolate concentration was higher in seeds than in leaves, varying from 3.8-fold in oilseed crops to 7.1-fold in root vegetable crops. Aliphatic glucosinolates predominated in both organs. In seeds, aliphatic glucosinolates represented between 91% to 94% in the different groups, whereas in leaves there was more variation. For root vegetable crops, aliphatic glucosinolates represented 80% of the total glucosinolate concentration. For leafy and forage types, aliphatic glucosinolates represented approximately 90% and for oilseed crops represented 92%. Indole glucosinolates were more abundant in leaves (5% to 17%) than in seeds (5% to 8%). The total glucosinolate content in leaves ranged from 14 to 24 μmol·g−1 dry weight (DW) in oilseed and forage types, respectively, whereas in the seeds, it ranged from 55 to 115 μmol·g−1 DW in oilseed and forage types, respectively. Significant differences were noted among the four groups in glucosinolate concentration and glucosinolate composition. In the seeds, progoitrin was found as the main glucosinolate in all groups. In the leaves, two different glucosinolate profiles were found depending on the crop: forage and root vegetable crops showed high levels of progoitrin, whereas glucobrassicanapin was the main glucosinolate for oilseed and leafy crops. We suggest that different selection criteria applied on B. napus crops according to their use could have led to an indirect selection for glucosinolate profile in leaves.
The Hyperbolic and Linear Phases of the Sucrose Accumulation Curve in Turnip Storage Cells Denote Carrier-mediated and Fluid Phase Endocytic Transport, Respectively
Authors: Pozueta-Romero Diego , Gonzalez Pedro , Etxeberria Ed , Pozueta-Romero Javier
Published: January 2019

Sucrose accumulation into sink cells consists of multiple components collectively characterized by a biphasic kinetics curve. Whereas the hyperbolic phase at low external sucrose concentration denotes a membrane-bound, carrier-mediated component, the linear nonsaturable phase at higher concentrations has been suggested to represent facilitated diffusion. We recently demonstrated the occurrence of fluid phase endocytosis (FPE) uptake of sucrose in heterotrophic cells. To investigate the involvement of this process within both phases of the sucrose accumulation curve, we analyzed the effect of phloridzin and latrunculin-B (sucrose/H+ symport and endocytosis inhibitors, respectively) in the accumulation of sucrose and the endocytic marker Alexa-488 in turnip (Brassica campestris L.) storage parenchyma cells. At low external sucrose concentration, phloridzin, but not latrunculin-B, greatly reduced sucrose accumulation. By contrast, at high external sucrose concentration, phloridzin and latrunculin-B significantly inhibited sucrose accumulation. In addition, latrunculin-B exerted a pronounced inhibitory effect on Alexa-488 uptake at any external sucrose concentration. Our results indicate that carrier-mediated and endocytic uptake (at different magnitudes) of sucrose take place at any external sucrose concentration; that within the hyperbolic phase of the sucrose accumulation curve, most of the sucrose accumulating in the cell enters via plasmalemma-bound carrier(s); and that within the linear phase, plasmalemma-bound carriers and FPE are determinants of sucrose accumulation, with the involvement of FPE increasing parallel to external sucrose. Confocal laser scanning microscopy observations confirmed the increased involvement of FPE at higher external sucrose concentrations.
Effects of Nitrogen Supply on Source-sink Balance and Fruit Size of ‘Gala’ Apple Trees
Authors: Xia Guohai , Cheng Lailiang , Lakso Alan , Goffinet Martin
Published: January 2019

The objective of this study was to determine how nitrogen (N) supply affects the source-sink balance and fruit size of ‘Gala’ apple when crop load was controlled at a moderate level. Five-year-old ‘Gala’/‘M.26’ trees grown in sand culture and trained in tall spindle received a total of 3.3, 10.0, 20.0, or 40.0 g actual N through fertigation using Hoagland's solution from bloom to 3 weeks before harvest. The crop load of these trees was adjusted to 6.5 fruit/cm2 trunk cross-sectional area by hand thinning when the diameter of the largest fruit was 10 mm. As N supply increased, total shoot leaf area in the canopy increased, whereas total spur leaf area remained unchanged. Both single leaf and whole canopy net CO2 assimilation rates increased with increasing N supply. The net dry matter gain of the whole tree from budbreak to fruit harvest increased ≈74% from the lowest N supply to the highest N supply, but the proportion of net dry matter gain partitioned to fruit (harvest index) decreased from 83% to 70%. Both leaf area to fruit ratio and average final fruit size increased with increasing N supply, and a linear relationship was found between leaf area to fruit ratio and final fruit size. The number of cells per fruit increased with increasing N supply, whereas average cell size remained unchanged. As N supply increased, fruit soluble solids concentration increased, whereas fruit firmness decreased slightly. These results indicate that 1) apple trees grown under low N supply are source-limited; and 2) within the range of N supply used, increasing N supply improves leaf N status, leaf and whole tree photosynthetic capacity, and leaf area to fruit ratio, leading to more cells per fruit, larger fruit, and higher soluble solids.
Effect of Preharvest Application of a Second-generation Harpin Protein on Microbial Quality, Antioxidants, and Shelf Life of Fresh-cut Lettuce
Authors: Fonseca Jorge M. , Kim Hyun-Jin , Kline Wesley L. , Wyenandt Christian A. , Hoque Murshidul , Ajwa Husein , French Ned
Published: January 2019

The effect of preharvest application of a newly developed second-generation harpin product (2G-Harpin) on shelf life of fresh-cut lettuce (Lactuca sativa) was investigated. The lettuce plants were grown in three locations in the United States: Watsonville, CA, Cedarville, NJ, and Yuma, AZ, and treated 5 days before harvest at 140, 280, and 420 g·ha−1 (30, 60, and 90 mg·L−1). Lettuce processed and bagged were stored at 1 to 3 °C and evaluated for quality for 20 days. Lettuce from California treated with 2G-Harpin at 280 to 420 g·ha−1 consistently showed better visual quality and lower microbial population than the control. Overall results in New Jersey showed no major differences among treatments. In Arizona, microbial population was lower and visual quality was higher in lettuce treated at 280 and 420 g·ha−1 during part of the storage period. In further experimentation, we examined the phenolic content of lettuce harvested 1 and 7 days after treatment with 2G-Harpin. The results showed that phenolic content was higher in all treated lettuce than in the control lettuce after 24 h. Six days later, the levels fell back to the initial stage. Antioxidants capacity increased by 40% in head leaves when plants were treated with 280 and 420 g·ha−1 2G-Harpin, but no change was observed in outer leaves. Overall, it was revealed that a field application of 2G-Harpin can improve quality of fresh-cut lettuce under environmental conditions that need to be determined. Our results with phenolic content and antioxidant activity suggested that improvement in quality is probably the result of alteration of metabolites' composition and demonstrated that increased phenolics do not correlate with lower quality of fresh-cut products.
Postharvest Changes in Internal Fruit Quality in Apples with Sunburn Browning
Authors: Schrader Larry E. , Zhang Jianguang , Sun Jianshe , Xu Jizhong , Elfving Don C. , Kahn Cindy
Published: January 2019

Postharvest changes in flesh firmness, soluble solids concentration (SSC), and titratable acidity (TA) associated with increasing severity of sunburn browning of apples (Malus ×domestica Borkh.) were investigated over time in regular atmosphere cold storage. In 2005, ‘Gala’ apples were harvested at maturity and sorted into five classes ranging from no sunburn (Sb-0) to severe sunburn browning (Sb-4). Flesh firmness, SSC, and TA were measured on flesh tissue beneath the sunburned area of the apples at harvest and at monthly intervals for 6 months. In 2006, a similar protocol was used for ‘Gala’, ‘Golden Delicious’, ‘Jonagold’, ‘Granny Smith’, and ‘Fuji’ apples, except that these fruit quality traits were determined at harvest and after 3 and 6 months in regular atmosphere cold storage. Flesh firmness and SSC increased, but TA decreased both years in all cultivars as sunburn severity increased from Sb-1 to Sb-4. The patterns of higher firmness with more severe sunburn browning persisted during cold storage even though firmness in all classes of fruit decreased gradually with time in cold storage. The patterns of lower TA as severity of sunburn increased also persisted during cold storage, but TA declined more markedly in apples with more severe sunburn. The ratio of SSC to TA (SAR) increased as the severity of sunburn increased in all five cultivars. The SAR also increased dramatically from harvest to 3 and 6 months after harvest with ratios exceeding 200 in Sb-4 of some cultivars after 6 months storage. This occurred because TA declined very markedly as time in cold storage increased. Relative water concentration of tissue in sunburned areas of apples declined as the severity of sunburn increased, and helps to account for the higher SSC and firmness observed in sunburned apples.
A Gamma-ray–Induced Dwarf Mutant from Seeded Bermudagrass and Its Physiological Responses to Drought Stress
Authors: Chen Chuanhao , Lu Shaoyun , Chen Youguang , Wang Zhongcheng , Niu Yuejing , Guo Zhenfei
Published: January 2019

Breeding for dwarf-type bermudagrass (Cynodon dactylon) with enhanced drought resistance is important for producing quality turf with reduced irrigation. A dwarf-type mutant (S-20–1) that exhibits slower vertical growth, and shorter internodes and leaf length was selected from the gamma-ray–irradiated seeds of a bermudagrass cultivar Sundevil II (S-CK). S-20–1 had slower turf coverage than S-CK. Compared with S-CK, the vertical growth of S-20–1 was more promoted by gibberellin (GA3) treatment. S-20–1 showed an enhanced drought resistance in greenhouse and field tests. Under drought stress, S-20–1 maintained higher relative water content and lower levels of ion leakage, malondialdehyde, and leaf firing than S-CK. Antioxidant enzyme activities and antioxidant content showed no difference between S-20–1 and S-CK under well-watered conditions, while higher enzyme activities were maintained in S-20–1 under drought stress. Free proline accumulated in response to drought stress and showed a positive correlation to the increased ion leakage, while S-20–1 had lower levels than S-CK. Our results indicated that the dwarfism in S-20–1 induced by gamma-ray irradiation might be the result of less GA3 or decrease of sensitivity to GA3 in the mutant. The improved drought resistance of the mutant is associated with maintenance of higher levels of antioxidant enzyme activities. More accumulation of proline in S-CK than S-20–1 reflected a physiological response to the drought-induced injury rather than an association with drought resistance of S-20–1.
Anthocyanin Regulatory/Structural Gene Expression in Phalaenopsis
Authors: Ma Hongmei , Pooler Margaret , Griesbach Robert
Published: January 2019

Anthocyanin biosynthesis requires the coordinated expression of Myc, Wd, Chs, Dfr, and Myb. Chs and Dfr are structural genes, while Myc, Myb, and Wd are regulatory genes. Reverse transcription polymerase chain reaction was used to measure the expression of these genes in Phalaenopsis amabilis and Phalaenopsis schilleriana. P. amabilis expresses an albescent phenotype with petals and sepals that are anthocyanin free, while P. schilleriana has a wild-type phenotype with anthocyanin-containing petals and sepals. As expected, the petals and sepals of P. schilleriana expressed high levels of Chs and Dfr. The petals and sepals of P. amabilis expressed high levels of Chs and very low levels of Dfr. In P. amabilis and P. schilleriana, anthocyanin-specific Myc and Wd were expressed; however, Myb specific for anthocyanin biosynthesis were undetectable in P. amabilis. This suggests that the absence of Myb expression was responsible for the lack of dihydroflavonol 4-reductase and results in the absence of anthocyanin pigmentation in P. amabilis petals and sepals. This was confirmed by particle bombardment of P. amabilis petals with functional Mybs isolated from P. schilleriana. Comparisons of anthocyanin-related Myb gene expression between P. schilleriana and P. amabilis are between genetically different species. Phalaenopsis ‘Everspring Fairy’ expresses a harlequin phenotype with white petals and sepals containing large anthocyanin sectors. Harlequin flowers are ideal to evaluate anthocyanin-related Myb gene expression within genetically identical but differently pigmented tissue. High levels of anthocyanin-specific Myb and Dfr transcripts were present in the purple, but not in the white, sectors of Phalaenopsis ‘Everspring Fairy’ petals and sepals. There was no differential expression of Chs, Wd, and Myc between the purple and white sectors. These results are in agreement with the results from P. amabilis and P. schilleriana.
Effects of Boron Deficiency on Geranium Grown under Different Nonphotoinhibitory Light Levels
Authors: Mishra Sasmita , Heckathorn Scott , Frantz Jonathan , Yu Futong , Gray John
Published: January 2019

Apart from a role in cell wall structure, specific functions for boron (B) in plants are unclear; hence, responses and adaptations to B stress are incompletely understood. We tested hypotheses that net photosynthesis (Pn) decreases with B deficiency before visible foliar symptoms and that higher nonphotoinhibitory light levels enhance soluble carbohydrate status and therefore mitigate B deficiency. Geranium (Pelargonium ×hortorum L.H. Bailey cv. Nittany Lion Red) plants were grown hydroponically and were then exposed to normal (45 μm) or deficient (0 μm) B at two light levels [100 or 300 μmol·m−2·s−1 photosynthetically active radiation (PAR)]. Photosynthesis [net CO2 uptake, carboxylation, and photosystem II (PSII) efficiency] was monitored for 5 days, as were concentrations of B, chlorophyll, soluble sugars, total protein, and several photosynthetic and stress proteins [ribulose 1,5-bisphospate carboxylase oxygenase (rubisco), rubisco activase, oxygen-evolving complex-23 (OEC23), Cu/Zn-superoxide dismutase (SOD), Mn-SOD, and eukaryotic translation initiation factor 5A-2 (eIF5A-2)]. Biomass and sugar concentration were greater in high light, and mass was decreased by B deficiency only in leaves in high light. Boron deficiency decreased [B] in all tissues, especially in new leaves. Carboxylation efficiency and Pn decreased within 1 day of B deficiency in low light, but not until 5 days in high light. Chlorophyll concentration decreased, and Mn-SOD increased transiently, with B deficiency in both light levels, but no other effects of low B were observed. Protection of Pn by higher light was confirmed in a different cultivar (Maverick White) grown at 100, 300, and 500 μmol·m−2·s−1 PAR. Thus, in geranium, photosynthesis is affected by B deficiency before effects on leaf growth, and higher light can at least temporarily ameliorate B deficiency, perhaps partly due to enhanced carbohydrate status.
Analysis of the ‘A72’ Peach Tree Growth Habit and Its Inheritance in Progeny Obtained from Crosses of ‘A72’ with Columnar Peach Trees
Authors: Hu Dongyan , Scorza Ralph
Published: January 2019

Since the first report of the ‘A72’ semidwarf peach [Prunus persica (L.) Batsch] tree in 1975, no new information has become available on this genotype. We evaluated the growth habit and verified the inheritance of ‘A72’ in a population of 220 progeny derived from self-pollination. Detailed tree and branch measurements revealed a unique forked-branch (FBR) character of the ‘A72’ (Nn) phenotype. The progeny segregated into 1 NN:2 Nn:1 nn. NN trees were indistinguishable from standard peach trees, Nn were FBR, and nn were dwarf. Hybrids between ‘A72’ and columnar (brbr) peach trees confirmed that FBR is inherited as a monogenic trait that appears to express incomplete dominance. ‘A72’ (Nn) trees were later blooming than sibling NN trees. The relationship (linkage or pleiotropy) between the growth habit of ‘A72’ and late bloom is not known. The structure of ‘A72’ trees presents new opportunities to breeder/geneticists, physiologists, and horticulturists to further explore the plasticity of peach tree growth and architecture that can be achieved through breeding. Applications of the ‘A72’ growth habit for commercial fruit production and as an ornamental, particularly in the dwarf form (nn) and in combination with the columnar tree (brbr) form, present opportunities that await exploration.