bluuebunny/crossref_metadata_2025 huggingface dataset:
A Moderate to High Red to Far-red Light Ratio from Light-emitting Diodes Controls Flowering of Short-day Plants
Authors: Craig Daedre S. , Runkle Erik S.
Published: January 2019

In protected cultivation of short-day (SD) plants, flowering can be inhibited by lighting from incandescent (INC) lamps during the night. INC lamps are being phased out of production and replaced by light-emitting diodes (LEDs), but an effective spectrum to control flowering has not been thoroughly examined. We quantified how the red [R (600 to 700 nm)] to far red [FR (700 to 800 nm)] ratio (R:FR) of photoperiodic lighting from LEDs influenced flowering and extension growth of SD plants. Chrysanthemum (Chrysanthemum ×morifolium), dahlia (Dahlia hortensis), and african marigold (Tagetes erecta) were grown at 20 °C under a 9-hour day with or without a 4-hour night interruption (NI) treatment by INC lamps or LEDs with seven different R:FR ranging from all R to all FR. Flowering in the most sensitive species, chrysanthemum, was not inhibited by an R:FR of 0.28 or lower, whereas an R:FR of 0.66 or above reduced flowering percentage. Flowering in dahlia was incomplete under the FR-only NI and under SDs, but time to flower was similar under the remaining NI treatments. The least sensitive species, african marigold, flowered under all treatments, but flowering was most rapid under the FR-only NI and under SDs. For all species, stem length increased quadratically as the R:FR of the NI increased, reaching a maximum at R:FR of ≈0.66. We conclude that in these SD plants, a moderate to high R:FR (0.66 or greater) is most effective at interrupting the long night, blue light is not needed to interrupt the night, and FR light alone does not regulate flowering.
Interspecific Hybridizations in Ornamental Flowering Cherries Validated by Simple Sequence Repeat Analysis
Authors: Pooler Margaret , Ma Hongmei
Published: January 2019

Flowering cherries belong to the genus Prunus, consisting primarily of species native to Asia. Despite the popularity of ornamental cherry trees in the landscape, most ornamental Prunus planted in the United States are derived from a limited genetic base of Japanese flowering cherry taxa. Controlled crosses among flowering cherry species carried out over the past 30 years at the U.S. National Arboretum have resulted in the creation of interspecific hybrids among many of these diverse taxa. We used simple sequence repeat (SSR) markers to verify 73 of 84 putative hybrids created from 43 crosses representing 20 parental taxa. All verified hybrids were within the same section (Cerasus or Laurocerasus in the subgenus Cerasus) with no verified hybrids between sections.
Canopy Position Affects Pigment Expression and Accumulation of Flavedo Carbohydrates of ‘Nules Clementine’ Mandarin Fruit, Thereby Affecting Rind Condition
Authors: Cronje Paul J.R. , Barry Graham H. , Huysamer Marius
Published: January 2019

Because photosynthesis provides the required carbohydrates for fruit development and respiration releases the stored energy from these carbon compounds, interalia during postharvest storage, it is therefore important that fruit tissues have an adequate carbohydrate concentration at the start of the postharvest period to ensure optimal storage life. In addition to photosynthate supply from leaves, the chlorophyll-containing flavedo of citrus (Citrus sp.) fruit (outer, colored part of the rind) has the ability to fix CO2 through its own photosynthetic system. In this experiment, spanning three seasons, the three main sugars (sucrose, glucose, and fructose) were quantified in the flavedo of ‘Nules Clementine’ mandarin (Citrus reticulata) fruit during Stages II and III of fruit development. Flavedo was sampled from fruit borne on the inside (low light intensity) or outside (high light intensity) of the tree’s canopy. In one season, the photosynthetic and respiration rates of fruit borne in the two canopy positions were measured pre- and post-color break (March and April, respectively). Sucrose concentration increased constantly from initial sampling in February until harvest (May), whereas glucose and fructose concentrations increased significantly only during the last month of fruit development. The flavedo of inside fruit, developing under low-light conditions, was less well colored (higher hue angle) and had a lower sugar concentration compared with outside fruit developing under conditions of high light levels. This response could be attributed to the higher pigment concentration leading to a higher photosynthetic rate as well as greater sink strength of the outside fruit. The inside fruit had an increased susceptibility to the progressive postharvest physiological disorder, rind breakdown. The lower carbohydrate and pigment concentrations of the rind from fruit borne inside the canopy compared with those from the outside of the canopy could be indicative of a weaker rind condition at the time of harvest.
Time-of-flight Near-infrared Spectroscopy for Nondestructive Measurement of Internal Quality in Grapefruit
Authors: Kurata Yohei , Tsuchida Tomoe , Tsuchikawa Satoru
Published: January 2019

We proposed a technique combining time-of-flight (TOF) and near-infrared spectroscopy (NIRS), termed TOF-NIRS, capable of measuring the time-resolved profiles of near-infrared (NIR) light with nanosecond resolution. Analysis of the variation in time-resolved profiles was used to estimate soluble solids concentration (SSC) and acidity in grapefruit (Citrus paradisi), and the prediction accuracy was compared with the conventional NIR measurement device. In data processing, the cross-correlation function, which evaluated the similarity between the reference and transmitted beams, was introduced as an explanatory variable for partial least squares regression. TOF-NIRS predicted both SSC and acidity in grapefruit with higher precision than the conventional NIR measurement with respective r values of 0.72 and 0.85. Specifically, the superiority of TOF-NIRS was attributed to measurement time and prediction accuracy in determining acidity.
Four Hypotheses to Explain Axillary Budbreak after Removal of Flower Shoots in a Cut-rose Crop
Authors: Wubs A. Maaike , Heuvelink Ep , Marcelis Leo F.M. , Okello Robert C.O. , Shlyuykova Alisa , Buck-Sorlin Gerhard H. , Vos Jan
Published: January 2019

When flower-bearing shoots in cut-rose (Rosa ×hybrida) are harvested (removed), a varying number of repressed axillary buds on the shoot remainder start to grow into new shoots (budbreak). Besides removing within-shoot correlative inhibition, it is hypothesized that shoot removal leads to 1) increased light intensity lower in the crop canopy; 2) changes in the light spectrum (particularly red:far-red ratio); and 3) changed source:sink ratio (i.e., the ratio between supply and demand of assimilates). As a fourth hypothesis it is proposed that the degree of budbreak on a shoot remainder is also influenced by the correlative inhibition exerted by other shoots on the plant. It is the goal of this work to determine which of these four hypotheses is most important for budbreak in a cut-rose crop. Four experiments were conducted, in which these factors were varied by leaf removal, removal of mature shoots, varying the number of young shoots, shading of the crop, and application of direct light on the buds. Increase in source:sink ratio was not consistently associated with higher budbreak. If source:sink ratio was decreased by removal of leaves or a mature shoot, budbreak showed even a tendency to increase. Budbreak was subject to correlative inhibition exerted by other shoots on the plant. Treatments where more light reached the bud (as a result of less shoots, no shading of the crop, application of local light) increased budbreak. Increased red:far-red ratio had the same result as more light reaching the bud but was often interrelated with light intensity. It was concluded that after removal of the flower-bearing shoot, among the factors tested, light intensity on the buds was an important and consistent factor explaining budbreak on the shoot remainder, whereas the effect of light spectrum should be further investigated.
Quantitative Genetic Analysis of Three Important Nutritive Traits in the Fruit of Avocado
Authors: Calderón-Vázquez Carlos , Durbin Mary L. , Ashworth Vanessa E.T.M. , Tommasini Livia , Meyer Kapua K.T. , Clegg Michael T.
Published: January 2019

Avocado (Persea americana) is a subtropical tree prized for its large and nutritious fruit. Although native to Mesoamerica, avocado is now grown in tropical and subtropical regions around the world, and consumer demand for avocado continues to grow at a considerable rate. Despite the appeal of avocado, its genetic improvement has been slow owing to substantial land and labor requirements combined with the fact that young trees do not produce fruit for several years and a pollination system that makes it difficult to produce genetic crosses. Molecular markers promise to accelerate the rate of breeding progress, especially for simple traits of high heritability. One of the distinguishing features of the avocado fruit is the presence of a number of compounds that have been linked to human health. As a prelude to the use of molecular markers for the improvement of nutritional traits, this article reports estimates of the heritability of carotenoids, β-sitosterol, and α-tocopherol content (the most biologically active form of vitamin E) in ripe avocado fruit. Each of these three compounds has been linked to beneficial health outcomes, and each is shown to have a sufficiently high heritability to predict successful marker-assisted selection.
Physiological Responses of Ivy Geranium ‘Beach’ and ‘Butterfly’ to Heat Stress
Authors: Dhir Ritu , Harkess Richard L. , Bi Guihong
Published: January 2019

The development of bleaching of the youngest leaves of actively growing ivy geranium (Pelargonium peltatum) has been observed as the season progresses from late spring to summer. Cultivar differences in foliar bleaching in response to elevated air temperature were studied. Ivy geranium ‘Beach’ and ‘Butterfly’ were grown in media containing sphagnum peat and perlite (70:30 v/v) for 6 weeks in modified greenhouse chambers with air temperatures averaging 28/16 or 36/22 °C (day/night). ‘Beach’ had greater plant width, growth index, leaf area, total fresh weight, and total dry weight than ‘Butterfly’ regardless of temperature. Overall, elevated air temperatures severely reduced plant width, plant growth index, leaf area, fresh weight, and dry weight of ivy geraniums. Elevated air temperatures caused foliar bleaching in both cultivars; however, ‘Butterfly’ was more susceptible to bleaching than ‘Beach’. ‘Beach’ had higher chlorophyll (Chl) b and total Chl content than ‘Butterfly’ at ambient air temperature, but they were similar at elevated air temperatures. Regardless of temperature, ‘Beach’ had greater Chl a, carotenoids (Caro), and pheophytins content but lower Chl a:Caro, Chl b:Caro, and total Chl:Caro ratios than ‘Butterfly’. This may contribute to the lower susceptibility to bleaching of ‘Beach’. Elevated air temperatures reduced Chl a, Caro, Chl a:Caro, Chl b:Caro, total Chl:Caro, and pheophytins content of ivy geraniums. In both cultivars, manganese (Mn) content increased with elevated air temperatures, but ‘Beach’ had greater Mn content than ‘Butterfly’. Total iron (Fe) content did not vary with cultivar or temperature. Irrespective of temperature, zinc (Zn) content was greater in ‘Beach’ than ‘Butterfly’, and irrespective of cultivar, Zn content was greater at elevated air temperatures. These results suggest greater chlorophyll, carotenoids, pheophytins, foliar Mn, and Zn contents play a role in reduced susceptibility of ‘Beach’ to foliar bleaching.
Effects of Whole-root and Half-root Water Stress on Gas Exchange and Chlorophyll Fluorescence Parameters in Apple Trees
Authors: Yuan Jinhong , Xu Man , Duan Wei , Fan Peige , Li Shaohua
Published: January 2019

The responses of photosynthesis, chlorophyll fluorescence, and de-epoxidation state of the xanthophyll cycle pigments (DEPS) of micropropagated apple trees (Malus ×domestica) were investigated under whole-root water stress (WRS) and half-root water stress (HRS) induced by polyethylene glycol 6000 to simulate whole and partial root zone drying. Compared with control plants without water stress, plants under WRS and HRS exhibited reduced leaf net photosynthetic rate (Pn) and stomatal conductance (gS) with a greater reduction in WRS than in HRS plants. However, intercellular CO2 concentration (Ci) increased under WRS as water stress was prolonged, signifying a non-stomatal limitation of Pn. Regarding HRS, decreased Pn was mainly the result of a stomatal limitation explained by a relatively low Ci. Changes in photosynthesis and chlorophyll parameters indicate that severe and slight damage occurred to the photosynthetic apparatus of WRS and HRS leaves, respectively, starting at Day 3 after initiating water stress. This damage was not evident on the donor side but was expressed as a reduced capacity of the acceptor side of the photosystem II reaction centers. To prevent damage from excess light, the DEPS of WRS leaf increased. Decreased gS could explain reduced water use under an irrigation strategy of partial root zone drying in fruit trees.
A Novel Effect for Glycine on Root System Growth of Habanero Pepper
Authors: Domínguez-May Ángel V. , Carrillo-Pech Mildred , Barredo-Pool Felipe A. , Martínez-Estévez Manuel , Us-Camas Rosa Y. , Moreno-Valenzuela Oscar A. , Echevarría-Machado Ileana
Published: January 2019

Amino acids, a major fraction of the low-molecular-weight organic nitrogen in soil, act as signaling molecules that indicate the presence of nutrient-rich patches to the roots. To characterize the effects of amino acids on root growth, we used seedlings of habanero pepper (Capsicum chinense), one of the most widely cultivated annual spice crops in the world. We tested the effect of L-glutamate, L-aspartate, and glycine on the primary root of seedlings grown aseptically under different conditions of pH and light. L-glutamate and L-aspartate did not inhibit the root growth of habanero pepper. In contrast, glycine inhibited the growth of roots, stimulated root hair growth, and induced a significant accumulation of starch grains in the root apex. The use of aminoethoxyvinylglycine, an inhibitor of ethylene biosynthesis, and the evaluation of 1-aminocyclopropane-1-carboxylic acid oxidase expression provided evidence of a role for ethylene in the root responses to glycine. We suggest that these changes in the root apex in response to exogenous glycine could be an important adaptive response that allows plants to efficiently access the fluctuating availability of nutrients in the soil.
Powdery Mildew Resistance in Gerbera: Mode of Inheritance, Quantitative Trait Locus Identification, and Resistance Responses
Authors: Song Xiaohe , Deng Zhanao
Published: January 2019

Gerbera (Gerbera hybrida) is an important floricultural crop in the United States and worldwide. Powdery mildew (PM) caused by Podosphaera xanthii is the most common and destructive disease in gerbera production and landscape use. Gerbera breeding line UFGE 31-19 is one of the few sources of resistance to PM in gerbera and has contributed its resistance to new gerbera cultivars. To determine the mode of inheritance for PM resistance in UFGE 31-19, one of its PM-resistant (PM-R) progeny, UFGE 4033, was crossed with PM-susceptible (PM-S) cultivar, Sunburst Snow White, and their progeny were evaluated for PM severity. Distribution of PM severity ratings among the progeny was continuous but with two peaks, suggesting that the PM resistance in UFGE 4033 and UFGE 31-19 is a quantitative trait, likely controlled by major genes. Bulked segregant analysis (BSA) identified 17 molecular markers present in UFGE 4033 and the PM-R bulk but absent in ‘Sunburst Snow White’ and the PM-S bulk. Eleven of the molecular markers were mapped to one genetic linkage group, and two regions on this linkage group together explained 71.1% of the phenotypic (PM severity rating) variance in the segregating population. It was proposed that the two regions be named Rpx1 and Rpx2 (resistance to P. xanthii). Conidia of P. xanthii inoculated on the leaf surface of UFGE 4033 germinated, formed secondary germ tubes, and formed appressoria at high percentages, similar to those on the leaf surface of ‘Sunburst Snow White’. However, P. xanthii hyphae branched significantly less, were significantly shorter, and produced substantially fewer conidia on the leaf surface of UFGE 4033 and its PM-R progeny than on the leaf surface of ‘Sunburst Snow White’. These results should provide a sound foundation for use of UFGE 31-19 and progeny UFGE 4033 in gerbera disease resistance breeding and facilitate further investigation and understanding of the genetic bases of PM resistance in gerbera.
Assessing the Genetic Diversity of Chrysanthemum Cultivars with Microsatellites
Authors: Zhang Yuan , Wang Chen , Ma HongZheng , Dai SiLan
Published: January 2019

The morphological characteristics of chrysanthemum (Chrysanthemum ×morifolium) are rich in variation. However, as a result of the aneuploid polyploidy of the chrysanthemum genome and the lack of proper tools, the genomic information of this crop is limited. Development of microsatellite markers has been an increasing trend in crop genetic studies because of the applicability of these markers in breeding programs. In this study, we reported the development of a simple sequence repeat in chrysanthemums using a magnetic beads enrichment method. An enriched genomic library with AC and GT microsatellite motifs was constructed, and 53 positive clones were detected by a colony polymerase chain reaction (PCR) technique. Of these clones, 35 showed high-quality sequences, and 35 primer pairs were designed accordingly. Twenty-six (74.29%) of the 35 primer pairs revealed polymorphisms on a set of 40 chrysanthemum cultivars. There were 172 alleles amplified over 26 loci with an average of 6.615 alleles per locus. The mean values of gene diversity corrected for the sample size and the inbreeding coefficient were 0.609 and 0.119 over 26 loci, respectively, which indicated that the majority of the microsatellite loci is highly informative. Cluster analysis based on 26 polymorphic loci demonstrated that the selected cultivars were clustered according to geographical origin. This study shows the isolation efficiency of the magnetic beads technique; the abundance of microsatellites in chrysanthemum; and the potential application for the cultivar classification, the studies on genetic diversity, and molecular breeding of chrysanthemums, which is beneficial to promoting the conservation and sustainable use of this crop.
Total Phenolic Content and Associated Phenotypic Traits in a Diverse Collection of Snap Bean Cultivars
Authors: Kleintop Adrienne E. , Myers James R. , Echeverria Dimas , Thompson Henry J. , Brick Mark A.
Published: January 2019

Phytochemicals such as phenolic compounds in snap bean (Phaseolus vulgaris) have potential human health benefits. The objectives of this research were to determine the variation in total phenolic content (TPC) measured as gallic acid equivalents (GAEs)—expressed on a fresh weight (FW) basis throughout this study—among a diverse collection of both indeterminate climbing (pole) and determinate (bush) bean cultivars (n = 149) using the Folin–Ciocalteu assay. We also evaluated associations between TPC and phenotypic traits and estimated genotype by environment (G × E) interactions in a subset of the cultivars. The TPC had greater than a 4-fold difference among cultivars and ranged from 0.29 to 1.31 mg·g−1 GAE (mean = 0.49 mg·g−1 GAE). Cultivars were classified into categories of high (≥1.00 mg·g−1 GAE), intermediate (>0.64 to <1.00 mg·g−1 GAE), and low (<0.55 mg·g−1 GAE) TPC. Eighty-four percent, 10%, and 6% of the cultivars fell into the low, intermediate, and high categories, respectively. The pole type cultivars had higher TPC (mean = 0.86 mg·g−1 GAE) when compared with the bush cultivars (mean = 0.47 mg·g−1 GAE). Correlations were observed between TPC and both flower and pod pigmentation. G × E interactions did not occur among pole type cultivars for TPC during 2 years of production, but a significant G × E interaction was observed among bush cultivars. The results demonstrate a wide diversity in snap bean cultivars for TPC, and the pole beans averaged higher TPC than bush bean cultivars. This information should be useful to identify high TPC snap bean cultivars.
Leaf Protein Abundance Associated with Improved Drought Tolerance by Elevated Carbon Dioxide in Creeping Bentgrass
Authors: Burgess Patrick , Huang Bingru
Published: January 2019

Elevated CO2 may contribute toward plant tolerance to prolonged drought stress. The objective of this study was to investigate changes in protein abundance associated with mitigation of drought stress by elevated CO2 in leaves of a cool-season grass species used as fine turfgrass. Plants of creeping bentgrass (Agrostis stolonifera cv. Penncross) were grown at either ambient CO2 concentration (400 µL·L−1) or elevated CO2 concentration (800 µL·L−1) for 35 days under well-irrigated and fertilized conditions and then subjected to drought stress for 21 days by withholding irrigation. Plants exposed to elevated CO2 concentration maintained higher leaf water content, membrane stability, and visual turf quality (TQ) under drought stress compared with plants grown under ambient CO2 conditions. The abundance of proteins involved in photosynthetic carbon fixation and assimilation, including chloroplastic glyceraldehyde phosphate dehydrogenase A (GAPDH-A) and ribulose 1,5-bisphosphate carboxylase (RuBisCO) decreased less and the abundance of proteins involved in respiratory metabolism (i.e., cytosolic GAPDH) increased less during drought due to elevated CO2. The results suggest that elevated CO2 lessened growth and physiological damages during drought by facilitating ribulose 1,5-bisphosphate regeneration and adenosine triphosphate (ATP) production in photosynthesis and downregulating factors contributing to respiratory metabolism.
A Novel Citrus Rootstock Tolerant to Iron Deficiency in Calcareous Soil
Authors: Fu Lina , Chai Lijun , Ding Dekuan , Pan Zhiyong , Peng Shu’ang
Published: January 2019

Iron (Fe) deficiency caused by calcareous soil is a serious problem in the cultivation of citrus (Citrus L.) trees. In this study, we report that ‘Zhique’ (Citrus wilsonii Tanaka) citrus rootstock from Chenggu county of Shaanxi province, China, shows tolerance to Fe deficiency under calcareous soil conditions. In the same calcareous field conditions, ‘Miyagawa Wase’ Satsuma mandarin (Citrus unshiu Marc.) grafted on trifoliate orange [Poncirus trifoliate (L.) Raf.] rootstock, the most commonly used rootstock, showed obvious interveinal chlorosis in young leaves, though some leaves or branches are asymptomatic, whereas no symptoms were found on those grafted on ‘Zhique’ rootstock. This was further evidenced by the fact that the chlorophyll concentration in chlorotic leaves of ‘Miyagawa Wase’ grafted on trifoliate orange was significantly lower than in those grafted on ‘Zhique’. In addition, transmission electron microscopy (TEM) analysis revealed a significant reduction of grana and stroma thylakoid of chloroplasts in chlorotic leaves. Measurement of Fe concentrations revealed that the total Fe and cell wall Fe showed no difference between ‘Zhique’ and trifoliate orange roots, whereas the ferrous Fe was significantly higher in ‘Zhique’ than trifoliate orange roots. Interestingly, both total Fe and ferrous Fe concentrations in chlorotic leaves were significantly lower than in green leaves of ‘Miyagawa Wase’ grafted on either ‘Zhique’ or trifoliate orange, whereas the cell wall Fe concentration of ‘Miyagawa Wase’ leaves only showed significant difference between the ‘Zhique’ and trifoliate orange samples. Further transcript assessment found that the Fe acquisition–related genes FIT, HA, FRO, and NRAMP were upregulated in roots of ‘Zhique’ compared with trifoliate orange, thus suggesting ‘Zhique’ might be more capable of Fe uptake under calcareous soil conditions. The novel citrus rootstock reported here could be used as an ideal material for Fe-uptake research, and as a Fe-deficiency-tolerant rootstock for citrus cultivation in calcareous soils.
Mapping Snap Bean Pod and Color Traits, in a Dry Bean × Snap Bean Recombinant Inbred Population
Authors: Hagerty Christina H. , Cuesta-Marcos Alfonso , Cregan Perry , Song Qijian , McClean Phil , Myers James R.
Published: January 2019

Snap bean (Phaseolus vulgaris L.) breeding programs are tasked with developing cultivars that meet the standards of the vegetable processing industry and ultimately that of the consumer, all the while matching or exceeding the field performance of existing cultivars. While traditional breeding methods have had a long history of meeting these requirements, genetic marker technology, combined with the knowledge of important quantitative trait loci (QTL), can accelerate breeding efforts. In contrast to dry bean, snap bean immature pods and seeds are consumed as a vegetable. Several pod traits are important in snap bean including: reduced pod wall fiber, absence of pod suture strings, and thickened, succulent pod walls. In addition, snap bean pods are selected for round pod cross section, and pods tend to be longer with cylindrical seed shape. Seed color is an important trait in snap bean, especially those used for processing, as processors prefer white-seeded cultivars. The objective of this study was to investigate the genetic control of traits important to snap bean producers and processors. RR6950, a small seeded brown indeterminate type IIIA dry bean accession, was crossed to the Oregon State University (OSU) breeding line OSU5446, a type I Blue Lake four-sieve breeding line to produce the RR138 F4:6 recombinant inbred (RI) mapping population. We evaluated the RR138 RI population for processing and morphological traits, especially those affecting pods. The RR138 population was genotyped with the BARCBean6K_3 Beadchip, and single nucleotide polymorphisms (SNPs) were used to assemble a linkage map, and identify QTL for pod traits. The linkage map produced from this study contained 1689 SNPs across 1196cM. The map was populated with an average of one SNP per 1.4 cM, spanning 11 linkage groups. Seed and flower color genes B and P were located on Pv02 and Pv07, respectively. A QTL for string:pod length (PL) ratio was found on Pv02 controlling 32% of total genetic variation. QTL for a suite of important processing traits including pod wall fiber, pod height, pod width, and pod wall thickness were found clustering on Pv04 and controlled 21%, 26%, 18%, and 16% of genetic variation for each of these respective traits. A QTL for PL was found on Pv09 controlling 5% of genetic variation.
Mechanical Properties of Skins of Sweet Cherry Fruit of Differing Susceptibilities to Cracking
Authors: Brüggenwirth Martin , Knoche Moritz
Published: January 2019

Rain cracking of sweet cherry fruit (Prunus avium L.) may be the result of excessive water uptake and/or of mechanically weak skins. The objectives were to compare mechanical properties of the skins of two cultivars of contrasting cracking susceptibility using biaxial tensile tests. We chose ‘Regina’ as the less-susceptible and ‘Burlat’ as the more-susceptible cultivar. Cracking assays confirmed that cracking was less rapid and occurred at higher water uptake in ‘Regina’ than in ‘Burlat’. Biaxial tensile tests revealed that ‘Regina’ skin was stiffer as indexed by a higher modulus of elasticity (E) and had a higher pressure at fracture () than ‘Burlat’. There was little difference in their fracture strains. Repeated loading, holding, and unloading cycles of the fruit skin resulted in corresponding changes in strains. Plotting total strains against the pressure applied for ascending, constant, and descending pressures yielded essentially linear relationships between strain and pressure. Again, ‘Regina’ skin was stiffer than ‘Burlat’ skin. Partitioning total strain into elastic strain and creep strain demonstrated that in both cultivars most strain was accounted for by the elastic component and the remaining small portion by creep strain. Differences in E and between ‘Regina’ and ‘Burlat’ remained even after destroying their plasma membranes by a freeze/thaw cycle. This indicates that differences in skin mechanical properties must be accounted for by differences in the cell walls, not by properties related to cell turgor. Microscopy of skin cross-sections revealed no differences in cell size between ‘Regina’ and ‘Burlat’ skins. However, mass of cell walls per unit fresh weight was higher in ‘Regina’ than in ‘Burlat’. Also, the ratio of tangential/radial diameters of epidermal cells was lower in ‘Regina’ (1.86 ± 0.12) than in ‘Burlat’ (2.59 ± 0.15). The results suggest that cell wall physical (and possibly also chemical) properties account for the cultivar differences in skin mechanical properties, and hence in cracking susceptibility.
Evaluation of Candidate Reference Genes for Quantitative Gene Expression Studies in Tree Peony
Authors: Zhou Lin , Shi Qianqian , Wang Yan , Li Kui , Zheng Baoqiang , Miao Kun
Published: January 2019

Quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) is a sensitive and widely used technique for gene expression analysis that depends on stability of the reference genes used for data normalization. Tree peony (Paeonia suffruticosa), known as one of the most famous traditional ornamental plants in China, is very popular in both domestic and international markets for its showy and colorful flowers. To date, no systematic studies on reference genes have been performed in tree peony with different flower colors. In this study, we evaluated the expression stability of 12 candidate reference genes in different tissues and five flower developmental stages of tree peony with six different colors by three algorithms: geNorm, NormFinder, and BestKeeper. The results showed that protein phosphatase 2A (PP2A), ubiquitin protein ligase (UPL), and ubiquitin (UBQ) were the most stable genes across all samples. Helicase, alpha-tubulin (TUA), and eukaryotic translation initiation factor 5A (EIF5A) also exhibited high expression stability in different tissues, in samples with different colors, and at different flower developmental stages. According to the geNorm analysis, the combination of two most stable reference genes was optimal for normalization in all tested sample sets in this study. To further validate the suitability of the reference genes identified in this study, the expression patterns of two putative homologs of chalcone synthase gene (PsCHS1) and chalcone isomerase gene (PsCHI1) were studied at different developmental stages of white flowers. The results provide information for transcriptional analyses in future studies of gene expression on tree peony flower development and pigmentation.
Cytokinin Dynamics during the Response to Nitrogen in Two Contrasting Plectranthus Genotypes
Authors: Paparozzi Ellen T. , Chahal Jazbaat K. , Dobrev Petre , Claassen Elizabeth A. , Stroup Walter W. , Vankova Radomira
Published: January 2019

Nitrogen response was compared in two Plectranthus species, Plectranthus parviflorus and Plectranthus ambiguus, which differ substantially in their phenotypic reaction to nitrogen limitation. The leaves of the former species gradually yellow during the nitrogen stress but are retained on the plant. This species copes with nitrogen deficiency also by gradual hydrolysis of starch grains. The latter species, P. ambiguus, responds by abscission of lower leaves. As plant hormones cytokinins are involved in nitrogen response as well as in regulation of the chlorophyll content, their dynamics were followed to explore the fast responses as well as the impact of nitrogen treatment. Both plant species responded to nitrogen deficiency/supplementation in similar ways, by downregulation and upregulation, respectively, of active cytokinins. However, the different phenotypic reactions imposed by nitrogen limitation were associated with specific regulation of cytokinin pool accompanying the stress response by the two species. The increase of the active cytokinins on nitrogen resupply was faster and stronger in the regreening species, P. parviflorus than in P. ambiguus. However, the P. ambiguus plants maintained higher basal levels of all cytokinin metabolites as well as chlorophyll content when compared with P. parviflorus. Nitrogen deficiency was associated in this species with accumulation of cis-zeatin-type cytokinins, which preceded abscission of lower and later on of middle leaves. The achieved results indicate that phenotypic variations in the response to nitrogen deficiency/supplementation are associated with significant quantitative and qualitative differences in the cytokinin pool.
Pollen Morphology of Herbaceous Peonies with Different Ploidy Levels
Authors: Hao Lihong , Ma Hui , Teixeira da Silva Jaime A. , Yu XiaoNan
Published: January 2019

The pollen morphology of 26 cultivars of herbaceous peony (Paeonia L.) was examined by scanning electron microscopy (SEM). Pollen grains of the cultivars were mostly subprolate to perprolate, tricolporate, or ellipsoidal in equatorial view, but rounded-trifid in polar view. The poles of pollen grains were mainly flat when viewed in cross-section and only a few appeared to have a circular or arc shape. In addition, the surface of the pollen grains was psilate, and the muri were partly or fully protuberant with a reticulate surface sculpture. However, the shapes and sizes of pollen grains as well as surface ornamentation varied significantly among cultivars with different chromosome numbers. The pollen grains from diploid cultivars were regular and full, and the reticulation holes were evenly distributed, while most of the pollen grains from triploid cultivars were empty flat shells with some heteromorphic pollen whose surface ornamentation was mostly rugulate-reticulate exine. The pollen grains from tetraploid cultivars were the largest although pollen morphology and surface ornamentation differed between Athena and Cream Delight. Six indices [polar axis length (P), equator axis length (E), P/E, pollen perforation diameter (D), ridge width (W), and D/W] were used in Q cluster analysis, which divided the 26 cultivars into three groups. Group I included eight diploid, four triploid, and one tetraploid cultivar. Group II included 12 triploid cultivars with complex genetic backgrounds. Group III included only one tetraploid cultivar Cream Delight. This work may provide an important palynological basis for studying taxonomy and hybrid breeding of herbaceous peony cultivars.
Volatile and Nonvolatile Flavor Chemical Evaluation of USDA Orange–Mandarin Hybrids for Comparison to Sweet Orange and Mandarin Fruit
Authors: Bai Jinhe , Baldwin Elizabeth , Hearn Jack , Driggers Randy , Stover Ed
Published: January 2019

Three citrus hybrids, containing 50% to 75% sweet orange (Citrus sinensis) genome in their pedigrees and similar to sweet orange in fruit size, color, and taste, were tested for their potential to be classified as new “sweet orange” cultivars. ‘Hamlin’, ‘Midsweet’, and three other early to midseason sweet oranges, along with ‘Dancy’ tangerine (Citrus reticulata), a typical mandarin, were used for comparison. Fruit were picked on 23 Jan. 2014, 30 Dec. 2014, and 27 Jan. 2015. A total of 114 volatiles were detected and separated into seven groups by detection frequency: three groups with 43 volatile components did not show differences and thus contributed little information for classification of sweet orange vs. mandarin, and the remaining four groups with 71 volatiles contributed to distinctions between orange and mandarin. Among the hybrids, the pattern of volatile detection frequency for hybrid FF-1-74-52 was virtually identical to sweet orange, and cluster analysis agreed with the classification. The number of average peaks were 55 to 62 in sweet oranges, 67 in FF-1-74-52, and 17 to 37 in tangerine and other hybrids. Quantity analysis of individual volatiles and chemical classes indicated that FF-1-74-52 and sweet oranges were rich in total volatile abundance, and almost all chemical classes including mono and sesquiterpenes, aldehydes, alcohols, ketones, and esters. This was especially true for ethyl butanoate, which contributes a fruity top note, and valencene and all sesquiterpene hydrocarbons, which only contribute to citrus flavor indirectly through their contribution to headspace partitioning. Two other hybrids, FF-1-75-55 and FF-1-76-51, each had some similarity to sweet oranges in several chemicals and classes, but not in the overall volatile profile. All three sweet orange–like hybrids met the standards for mandarins and oranges in soluble solids content, titratable acidity (TA), and the ratio. The above volatile and nonvolatile flavor chemical profile comparisons strongly support a proposal to classify FF-1-74-52 as a “sweet orange” commercially, and all three hybrids were previously shown to be more similar to sweet orange in their volatile profile than is ‘Ambersweet’. ‘Ambersweet’ was a hybrid that was legally classified as a “sweet orange” in 1995 based on its volatile profile.
Effects of Salicylic Acid and Calcium Chloride on Heat Tolerance in Rhododendron ‘Fen Zhen Zhu’
Authors: Shen Huifei , Zhao Bing , Xu Jingjing , Zheng Xizi , Huang Wenmei
Published: January 2019

Rhododendrons (Rhododendron) are ornamental plants that exhibit poor thermotolerance. Salicylic acid (SA) and Ca2+ regulate the physiological and biochemical mechanisms in plants adapted to adverse environmental conditions. This study investigated the role of SA and CaCl2 in managing heat tolerance of Rhododendron ‘Fen Zhen Zhu’. Plants of the triennial Rhododendron ‘Fen Zhen Zhu’ were pretreated with SA and CaCl2, alone and combined. Following this pretreatment, the plants were subjected to 38/30 °C (day/night) incubation for 6 days, and then allowed to recover for 20 days under 25/17 °C (day/night) in a chamber. Changes in morphology were observed and recorded. Data were collected on plant chlorophyll content, malondialdehyde (MDA) content, H2O2 level, antioxidant enzyme activity, and total soluble protein content. The results revealed that the plant growth was considerably affected by heat stress, the leaves became brown and withered, and the plant defoliated. Under heat stress, chlorophyll content and total soluble protein levels decreased. Peroxidase (POD) activity and superoxide dismutase (SOD) also decreased, whereas the H2O2 and MDA content increased. Individual or combined application of SA and CaCl2 had a positive effect on plant growth, chlorophyll content, total soluble protein levels, and enzymatic antioxidant activity under heat stress. In general, the effect of the combined application of SA and CaCl2 was superior to individual application. In addition, treatment with high CaCl2 concentrations effectively alleviated the decrease in chlorophyll content. However, at low SA and CaCl2 concentrations, SOD and POD activity and total soluble protein accumulation increased whereas MDA and H2O2 levels decreased. These results suggest that SA and CaCl2 may interact to alleviate heat stress.
Recurrent Full-sib Family Selection for Husk Extension in Sweet Corn
Authors: Moore Virginia M. , Tracy William F.
Published: January 2019

Corn earworm (Helicoverpa zea) is a costly and destructive pest in sweet corn (Zea mays) production. A recurrent selection experiment was conducted to assess the feasibility of selecting a sweet corn population for longer husks without shortening the ears and to determine whether direct selection for longer husks confers improved resistance to the corn earworm. The initial population was derived from crosses between long- and tight-husked inbred lines (A684su, A685su, and A686su) originally selected for resistance to the european corn borer (Ostrinia nubilalis) and a high-quality commercial hybrid parent (‘Super Sweet Jubilee Plus’). Three cycles of recurrent full-sib family selection were conducted from 2014 to 2016, with a selection intensity of ≈10% per cycle. In 2017, the cycles of selection were evaluated and compared with common commercial cultivars for husk extension, ear length, rate of corn earworm infestation, and extent of corn earworm damage. Ears were artificially infested with corn earworm eggs suspended in an agar solution. The population was successfully selected for longer husk extension without shortening the ears, but the increase in husk extension did not correspond to an increase in corn earworm resistance. Further evaluation is needed to determine whether long husk extension is ineffective as a source of corn earworm resistance, whether it is more effective in combination with other resistance traits, whether greater differences in husk extension are needed to confer biologically significant differences in corn earworm resistance, or whether improved inoculation methods could improve differentiation between genotypes.
DNA Damage and Oxidative Status of Full Term Babies Delivered by Spontaneous Vaginal Delivery and Caesarean Section
Authors: Kazanasmaz Halil , Abuhandan Mahmut
Published: January 2019

Objectives: At this study, it is aimed to research DNA damage and oxidative stress in infants with born timely normal spontaneous vaginal delivery (NSVD) and elective caesarean.Study Design: Healthy term babies born with NSVD (n=36) and elective caesarean section (n = 36) were included in the study. Determination of DNA damage was studied in fresh heparinized blood by the Comet Assay (mononuclear cell alkaline electrophoresis) method. Total oxidant capacity and total antioxidant capacity values were measured by using Erel method (colorimetric) on study day by autoanalysers and oxidative stress index values were calculated.Results: Mean total oxidant capacity, oxidative stress index and DNA damage values were significantly higher in babies born with NSVD compared to those born with elective cesarean section (p <0.001, p<0.001, p<0.001, respectively). Serum total antioxidant capacity values were not statistically significant (p=0.127).Conclusion: In this study, oxidative stress and DNA damage values of babies born with NSVD were found to be higher than those born by elective cesarean section. This suggests that there may be a relationship between the mode of delivery and oxidative stress, and that increased oxidative stress may also lead to DNA damage.
Coproduction of hydrogen and methane in a CSTR-IC two-stage anaerobic digestion system from molasses wastewater
Authors: Li Qiaoyan , Li Yongfeng
Published: January 2019

A continuous hydrogen and methane production system in a two-stage process has been investigated to increase energy recovery rate from molasses wastewater in this study. This system consisted of a continuous stirred-tank reactor for hydrogen production and an internal circulation (IC) reactor for methane production, and was studied under the influent organic loading rate (OLR) of 18, 24, 30 and 36kg COD/(m3·d) (COD: chemical oxygen demand). The maximum volumetric hydrogen production rate of 2.41 L/(L·d) was obtained at the OLR of 30kg COD/(m3·d) with a hydrogen content of 42%, and the maximum volumetric methane production rate of 2.4 L/(L·d) with a methane content of 74.45% was obtained at the OLR of 36kg COD/(m3·d) using the effluents of hydrogen fermentation as substrate. The maximum of 71.06% of the molasses wastewater energy was converted to biogas (hydrogen and methane) at the OLR of 30kg COD/(m3·d).
Hotspot Identification on Protein Surfaces Using Probe-Based MD Simulations: Successes and Challenges
Authors: Sayyed-Ahmad Abdallah
Published: January 2019

Molecular Dynamics (MD) based computational co-solvent mapping methods involve the
generation of an ensemble of MD-sampled target protein conformations and using selected small molecule
fragments to identify and characterize binding sites on the surface of a target protein. This approach
incorporates atomic-level solvation effects and protein mobility. It has shown great promise in
the identification of conventional competitive and allosteric binding sites. It is also currently emerging
as a useful tool in the early stages of drug discovery. This review summarizes efforts as well as discusses
some methodological advances and challenges in binding site identification process through
these co-solvent mapping methods.
Machine Learning Algorithms in the Prediction of Early Death in Elderly Cancer Patients (Preprint)
Authors: Sena Gabrielle , Lima Tiago Pessoa , Lima Jurema Telles , Mello Maria Julia , Thuler Luiz Claudio
Published: January 2019

BACKGROUND

The importance of classifying cancer patients into high or low risk groups has led many research teams, from the biomedical and the bioinformatics field, to study the application of Machine Learning (ML) algorithms. The International Society of Geriatric Oncology (SIOG) recommends the use of the Comprehensive Geriatric Assessment (CGA), a multidisciplinary tool to evaluate health domains, for the follow-up of elderly cancer patients. However, none ML application have been proposed using CGA to classify elderly cancer patients.

OBJECTIVE

To propose and develop predictive models, using ML and CGA, to estimate the risk of early death in elderly cancer patients.

METHODS

The ability of ML algorithms to predict early mortality in a cohort involving 608 elderly cancer patients was evaluated. The CGA was conducted during admission by a multidisciplinary team and included the following questionnaires: Mini-Mental State Examination, Geriatric Depression Scale, International Physical Activity Questionnaire, Timed Get-Up and Go, Katz Index, Charlson Comorbidity Index, Karnofsky Performance Scale, Polypharmacy, Mini Nutritional Assessment. The K-fold Cross Validation algorithm was used to evaluate all possible combinations of these questionnaires to estimate the risk of early death, considered when occurring within six months of diagnosis, in a variety of ML classifiers, including Naive Bayes (NB), Decision Tree (J48) and Multilayer Perceptron (MLP). On each fold of evaluation, tie-breaking is handled by choosing the smallest set of questionnaires.

RESULTS

It was possible to select CGA questionnaire subsets with high predictive capacity for early death, either statistically similar (NB) or higher (J48 and MLP) compared to the use of all questionnaires investigated. These results show that CGA questionnaire selection can improve accuracy rates and decrease the time spent to evaluate elderly cancer patients. The only questionnaire selected in all folds was the Mini Nutrition Evaluation. The Karnofsky Performance Scale was selected in all folds by the NB and MLP, while the Mini Mental State Examination was selected in all folds by the NB.

CONCLUSIONS

A simplified predictive model aiming to estimate the risk of early death in elderly cancer patients is proposed herein, minimally composed by the Mini Nutrition Evaluation accompanied or not by the Karnofsky Performance Scale and/or the Mini-Mental State Examination.