bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of Chrysanthemum in Response to Supplemental Light Provided by Irregular Light Breaks during the Night
Authors: Kjaer Katrine Heinsvig , Ottosen Carl-Otto
Published: January 2019

Circadian rhythms are believed to be of great importance to plant growth and performance under fluctuating climate conditions. However, it is unclear how plants with a functioning circadian clock will respond to irregular light environments that disturb circadian-regulated parameters related to growth. Chrysanthemum (Chrysanthemum morifolium ‘Coral Charm’) was exposed to supplemental light provided as irregular light breaks during the night, achieved by controlling the light based on forecasted solar irradiance and electricity prices. Growth, in terms of carbon gain, was linearly correlated to both daylength and daily light integral. This response was observed irrespective of the irregularity of the light breaks and despite circadian-regulated processes of carbohydrate metabolism, chlorophyll fluorescence, and leaf chlorophyll content being affected. Leaf expansion and stem elongation occurred at a faster rate in plants grown in short days with irregular light breaks during the night period compared with plants grown in a climate with a consecutive long light period, showing that low average light intensity promoted expansion of the photosynthetic area of the plants. These results are important to gain an understanding of the relationship between circadian-regulated processes and plant growth. These results will also contribute to increased energy savings in the use of supplemental light in greenhouse production.
Genotypic Variation in Fatty Acid Composition and Unsaturation Levels in Bermudagrass Associated with Leaf Dehydration Tolerance
Authors: Zhong Diheng , Du Hongmei , Wang Zhaolong , Huang Bingru
Published: January 2019

Fatty acid metabolism may be involved in plant adaptation to drought stress. The objective of this study was to identify saturated and unsaturated fatty acids associated with leaf dehydration tolerance by comparing fatty acid composition and unsaturation levels at equivalent leaf water status of two bermudagrass genotypes contrasting in drought resistance. A drought-resistant hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) genotype (‘Tifway’) and a drought-sensitive bermudagrass (C. dactylon) genotype (‘C299’) were maintained under well-watered (control) or water-withheld (drought) conditions. Drought treatment was imposed until soil water content decreased to 5% or leaf relative water content (RWC) dropped to 28% to 29%. ‘Tifway’ maintained higher RWC and lower electrolyte leakage (EL) at 5 and 10 days of drought stress. Leaves of ‘Tifway’ maintained lower EL when RWC of both genotypes declined to the same level of water deficit (28% to 29%) by the end of drought periods. The degree of fatty acid unsaturation, expressed as the double bond index, decreased in both genotypes during drought stress, which was mainly associated with the decline in linoleic (C18:2) and linolenic acids (C18:3) and an increase in palmitic (C16:0) and stearic acids (C18:0). A lipid composition characterized by a greater amount of unsaturated fatty acids was detected in ‘Tifway’ relative to ‘C299’ exposed to the same level of water deficit, mainly as a result of a greater content of C18:2 and a lower content of C16:0 and C18:0. Our results suggest that the ability to maintain a greater composition of unsaturated fatty acids in membrane lipids may contribute to superior leaf dehydration tolerance in bermudagrass.
Melting of ‘Big Top’ Nectarine Fruit: Some Physiological, Biochemical, and Molecular Aspects
Authors: Ghiani Alessandra , Negrini Noemi , Morgutti Silvia , Baldin Federica , Nocito Fabio F. , Spinardi Anna , Mignani Ilaria , Bassi Daniele , Cocucci Maurizio
Published: January 2019

‘Big Top’ nectarine [Prunus persica (L.) Batsch] has appreciable keeping quality because it resembles, at ripening, the stony hard (SH) peach (P. persica) in firmness and crispness but melts at a slow speed at full ripening. We have characterized the postharvest behavior of ‘Big Top’ fruit, treated or not with ethylene for 5 days after harvest (DAH), and compared it with that of a SH peach (‘Ghiaccio’). Pp-ACS1 expression, ethylene evolution, endo-polygalacturonase (endo-PG) production, and softening were evaluated and compared with those of the physiologically ripe melting flesh (M) cultivar Bolero. Like ‘Bolero’, ‘Big Top’ fruit expressed Pp-ACS1 and evolved ethylene but with a 5-day delay. Pp-endo-PG expression, production of an active endo-PG, and fruit melting showed a parallel behavior; ethylene treatment enhanced all these features. In SH ‘Ghiaccio’ Pp-ACS1 expression, ethylene evolution, endo-PG production, and softening were absent during the first 5 DAH in air. ‘Ghiaccio’ neither expressed Pp-ACS1 nor evolved ethylene even after ethylene treatment but responded by accumulating Pp-endo-PG transcripts and an active endo-PG protein, with flesh melting. A ‘Big Top’ Pp-endo-PG clone showed several single nucleotide (SNP) and insertion-deletion (InDel) polymorphisms in comparison with the M Pp-endo-PG clone of ‘Bolero’ and substantial similarity with the Pp-endo-PG clone of ‘Ghiaccio’. In ‘Big Top’, we identified a peculiar SNP (bp 348) and InDels shared with ‘Ghiaccio’, possibly suitable for discriminating among different genotypes. Overall, the data confirm the pivotal role of ethylene in the regulation of endo-PG production and in the determination of peach flesh texture and support the evidence that ‘Big Top’ could be classified as a melting (slow-melting) phenotype.
Seasonal Distribution of Micronutrients in Mature ‘Concord’ Grape: Boron, Iron, Manganese, Copper, and Zinc
Authors: Pradubsuk Suphasuk , Davenport Joan R.
Published: January 2019

This study investigated the distribution of the micronutrients boron (B), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in 42-year-old ‘Concord’ grapevines (Vitis labruscana Bailey) grown in a calcareous soil to understand seasonal partitioning and distribution of micronutrients throughout various grapevine tissues. In 2006 and 2007, four vines each were excavated at winter pruning, budbreak, the three- to four-leaf stage, bloom, veraison, harvest, and postharvest. Separated plant organs were measured for biomass and analyzed for B, Fe, Mn, Cu, and Zn. The results showed that seasonal patterns of micronutrient concentrations varied considerably with respect to organ and growth stage. Leaf blades, shoot tips, and petioles had the highest concentration of B at bloom and Mn at harvest, whereas Fe, Cu, and Zn concentrations were highest in fine roots but values varied over time each year. Whereas seasonal patterns of Fe, Cu, and Zn contents differed year by year, B and Mn contents had a similar pattern over both years. Translocation of B and Mn from woody tissue to actively growing organs occurred at the beginning of the season. The majority of B uptake occurred between bloom and veraison, whereas that of Mn occurred between bloom and harvest. There were similar B concentrations in shoot tips and leaf blades. Boron remobilization to woody tissues from the leaves occurred between veraison and harvest, suggesting moderate, late-season, phloem mobility of B in ‘Concord’ grapevines. Microsite differences in soil pH likely contribute to variable nutrient availability around the root system, demonstrated by high variability of Fe, Cu, and Zn contents in different vine organs.
Parthenogenic Haploids in Melon: Generation and Molecular Characterization of a Doubled Haploid Line Population
Authors: Gonzalo Maria Jose , Claveria Elisabet , Monforte Antonio J. , Dolcet-Sanjuan Ramon
Published: January 2019

Melon (Cucumis melo) is one of the principal vegetable crops for fresh market, for which a large number of breeding programs, oriented to generate inbred pure lines and hybrids, is established worldwide. The process to obtain and select these lines has been highly accelerated by the use of biotechnological techniques such as the generation of doubled haploid line (DHL) populations and molecular markers. Moreover, the use of DHLs in genetic studies is a useful tool because of their complete homozygosity and the permanent availability of plant material perpetuated by seed. In this work, the parthenogenetic response of 17 melon genotypes and the F1 hybrid PI 161375 × Spanish cultivar Piel de Sapo (PS) was studied considering three stages along the in vitro DHL generation process. The response of the analyzed melon cultivars was heterogeneous through the DHL generation with different limiting steps for each genotype. The response of the PI 161375 × PS hybrid was more similar to the male (PS) than the female parent (PI 161375), although the response of the maternal genotype was higher for some stages. This points to the important role of alleles from both parents in the different steps of the DHL generation process, and it could explain the identification of six genomic regions with distorted allelic segregation skewed toward PS or PI 161375. This hybrid was used to generate a population of 109 DHLs, the gametophytic origin of which was confirmed by flow cytometry and molecular markers.
A Morphological and Histological Characterization of Bisexual and Male Flower Types in Pomegranate
Authors: Wetzstein Hazel Y. , Ravid Nadav , Wilkins Erik , Martinelli Adriana Pinheiro
Published: January 2019

Pomegranate [Punica granatum (Punicaceae)] is characterized by having two types of flowers on the same tree: hermaphroditic bisexual flowers and functionally male flowers. This condition, defined as functional andromonoecy, can result in decreased yields resulting from the inability of male flowers to set fruit. Morphological and histological analyses of bisexual and male flowers were conducted using light and scanning electron microscopy (SEM) to characterize the different flower types observed in pomegranate plants and to better understand their developmental differences. Bisexual flowers had a discoid stigma covered with copious exudate, elongated stigmatic papillae, a single elongate style, and numerous stamens inserted on the inner wall of the calyx tube. Using fluorescence staining, high numbers of pollen tubes were observed growing through a central stylar canal. Ovules were numerous, elliptical, and anatropous. In contrast, male flowers had reduced female parts and exhibited shortened pistils of variable heights. Stigmatic papillae of male flowers had little exudate yet supported pollen germination. However, pollen tubes were rarely observed in styles. Ovules in male flowers were rudimentary and exhibited various stages of degeneration. Pollen from both types of flowers was of similar size, ≈20 μm, and exhibited similar percent germination using in vitro germination assays. Pollen germination was strongly influenced by temperature. Maximal germination (greater than 74%) was obtained at 25 and 35 °C; pollen germination was significantly lower at 15 °C (58%) and 5 °C (10%).
Construction of a Linkage Map and Identification of Resistance Gene Analog Markers for Root-knot Nematodes in Wild Peach, Prunus kansuensis
Authors: Cao Ke , Wang Lirong , Zhu Gengrui , Fang Weichao , Chen Chenwen , Zhao Pei
Published: January 2019

The root-knot nematode (RKN) Meloidogyne incognita can cause severe crop loss in economically important Prunus species like peach (P. persica), almond (P. communis), plum (P. salicina), and apricot (P. armeniaca). Some peach rootstock, including Nemaguard (P. persica), Nemared (P. persica), and Myrobalan plum (P. cerasifera), display significant resistance to RKN. We present a genetic linkage map constructed by using simple sequence repeat (SSR) and sequence-related amplified polymorphism (SRAP) for a peach backcross population (190 individuals) of RKN-resistant ‘Honggengansutao’ (P. kansuensis) and susceptible ‘Bailey’ (P. persica). Degenerate primers designed from conserved motifs of known plant resistance gene (R) products were used to amplify genomic DNA sequences. Twenty-two resistance gene analog (RGA) sequences were selected from 48 RGAs with open-reading frames to design sequence-tagged site markers. The linkage map of ‘Honggengansutao’ is composed of 138 loci (30 SSRs, 102 SRAPs, five RGAs, and one morphological marker for RKN resistance) assigned to eight linkage groups. The map covers 616 cM of the peach genome with an average marker spacing of 4.9 cM. The five RGAs were mapped to Groups 2, 7, and 8. One gene (designated PkMi) involved in resistance to RKN was mapped to Group 2 (which also includes the known RKN-resistance RMia gene). BLASTN analysis mapped all RGAs to the peach genome sequence. The map constructed in the study will aid future rootstock breeding with marker-assisted selection to identify additional candidate RGA sequences.
Identification of Simple Sequence Repeat Markers that Differentiate Bermudagrass Cultivars Derived from ‘Tifgreen’
Authors: Harris-Shultz Karen R. , Schwartz Brian M. , Brady Jeff A.
Published: January 2019

The release of the bermudagrass (Cynodon spp.) triploid hybrid ‘Tifgreen’ revolutionized southeastern U.S. golf course greens. Off-types within this cultivar began to be identified soon after the initial plantings, and through the last 50 years, many of the best performing off-types have been released as new cultivars. Examination of some of the most popular somatic mutants with a new set of 47 simple sequence repeat (SSR) markers and 23 previously discovered genomic SSR markers identified five polymorphic fragments (as compared with ‘Tifgreen’) among three cultivars, TifEagle, MiniVerde, and Tifdwarf. Each polymorphism appears to be a slight increase/decrease in microsatellite repeat number and the polymorphic fragments are unique for each cultivar. Two polymorphic fragments were identified that were unique to ‘Tifdwarf’, one polymorphic fragment was unique to ‘TifEagle’, and two polymorphic fragments were unique to ‘MiniVerde’. Furthermore, three of the five polymorphic markers display an additional allele only in the shoot tissue but not in the root tissue of ‘TifEagle’ and ‘Tifdwarf’. This finding suggests that ‘TifEagle’ and ‘Tifdwarf’ are somatic chimeras. This set of SSR markers identifies repeatable polymorphic fragments among multiple ‘Tifgreen’-derived cultivars and gives insight into the nature of the mutations that exist within ‘Tifgreen’.
Effect of Selenium Fertilization and Methyl Jasmonate Treatment on Glucosinolate Accumulation in Broccoli Florets
Authors: Kim Hyoung Seok , Juvik John A.
Published: January 2019

Broccoli (Brassica oleracea ssp. italica) is a rich source of glucosinolates (GSs), phytochemicals that are hydrolyzed into isothiocyanates with known human anticarcinogenic bioactivity. Increasing dietary intake of the element selenium (Se) can also reduce the risk of cancer. Previous research reported that Se fertilization at high concentrations reduces the concentration of GSs in brassicaceous plants. This research was conducted to determine the effect of Se fertilization on accumulation of different types of GSs in broccoli floret tissues in five genotypes. Methyl jasmonate (MeJA), an elicitor known to stimulate biosynthesis of indolyl GSs, was used to analyze changes in biosynthetic capability of indolyl GSs in broccoli floret tissue under Se-enriched conditions. Five broccoli genotypes were subjected to root fertilization with low and high levels of Na2SeO4 solutions (0.17 and 5.2 mm), MeJA sprays to aerial portions of the plants (250 μM), and the combined treatment of 5.2 mm Se with 250 μM MeJA, respectively. The effect of Se fertilization on GS accumulation varied among genotypes and the level of Se fertilization. Variation in the level of Se fertilization resulted in a dose-dependent decrease in glucoraphanin concentrations with no significant effect on indolyl GS accumulation in broccoli florets across the five genotypes. MeJA treatment increased indolyl and aromatic GS accumulation in floret tissues. MeJA-mediated increases in these GSs were inhibited in the high Se fertilization treatment, but the increase in neoglucobrassicin concentrations was less affected than other GSs in florets across the five genotypes. An experiment conducted with 6-week-old broccoli plants under the high Se treatment demonstrated greater accumulation of Se with depressed accumulation of sulfur and complete inhibition of MeJA-mediated indolyl GS accumulation compared with those changes in florets of mature broccoli plants. These results suggest that GS accumulation under Se fertilization may be influenced by not only the level of Se fertilization, but also the differences in sizes of available pools of resources (sulfur and sulfur-containing amino acids) required for GS biosynthesis and accumulation in broccoli plants. Partitioning of the variance indicated that the existence of substantial variability in GS concentrations was primarily attributed to differences in genotype response across different treatments. Results suggest that cultivar selection and breeding of broccoli can be used to develop broccoli germplasm with enhanced capacity for Se uptake and stability of GS biosynthesis with varying Se fertilization.
Chemometric Characterization of Almond Germplasm: Compositional Aspects Involved in Quality and Breeding
Authors: Kodad Ossama , Alonso José M. , Espiau María T. , Estopañán Gloria , Juan Teresa , Socias i Company Rafel
Published: January 2019

The oil content and the percentage of the main fatty acids were determined in a set of 73 almond (Prunus amygdalus Batsch) cultivars from 10 different countries present at the almond germplasm collection of the Centro de Investigación y Tecnología Agroalimentaria de Aragón, Spain (CITA). Wide variability was observed for oil content, ranging from 51.5% to 66.8% on a dry weight (DW) basis. For the main fatty acids in the lipid fraction, the variability ranged from 62.9% to 77.3% for oleic acid, from 14.0% to 26.8% for linoleic acid, from 4.9% to 7.0% for palmitic acid, from 1.5% to 3.4% for stearic acid, and from 0.3% to 0.6% for palmitoleic acid. No correlations were found between the oil content and the percentages of the different fatty acids, but a significant negative correlation was found between the percentages of oleic and linoleic acids. Principal component (PC) analysis showed that palmitic, oleic, and linoleic acids and the oleic acid/linoleic acid ratio were primarily responsible for the separation on principal component 1. The content of each component was not related to the country of origin of the different cultivars, indicating that almond fatty acid composition is genotype-dependent. Cultivars with high and stable oil content and low linoleic acid should be selected as parents in a breeding program to increase kernel oil stability and nutritional value.
Enzymatic Metabolism of Nitrogen in Leaves and Roots of Creeping Bentgrass under Nitrogen Deficiency Conditions
Authors: Jiang Zhongchun , Xu Chenping , Huang Bingru
Published: January 2019

Low nitrogen (N) rates are recommended for creeping bentgrass (Agrostis stolonifera) putting greens to prevent excessive shoot growth and potential nitrate leaching, but low N rates could lead to N deficiency, which induces leaf senescence. This study was conducted to examine the effects of N deficiency on two enzymes involved in organic N metabolism as well as amino acid (AA) and soluble protein (SP) contents in both young and old leaves and roots of creeping bentgrass. Creeping bentgrass plants (cv. Penncross) were grown in a nutrient solution containing either 6 mm nitrate (+N plants) or zero N (−N plants), and each of the two treatments had four replicate pots. Young leaves on upper portions of the stolons and old leaves on lower portions of the stolons were separated and sampled at 14, 21, and 28 days of treatment, and roots were sampled at 28 days. Nitrogen deficiency increased glutamine synthetase (GS) transferase activity in all three tissues and at all three dates and GS biosynthetic activity in young leaves at all three dates. Prolonged N deficiency at 21 and 28 days increased glutamate dehydrogenase (GDH) deamination and amination activities in old leaves. In the roots, N deficiency at 28 days increased GS transferase activity but decreased GDH deamination activity. The N deficiency decreased AA content in all three tissues and at all three dates and SP content in young leaves at all three dates and in old leaves at 21 and 28 days. Decreasing organic N reserves in AA and SP and increasing GS and GDH activities in senescing leaves may be adaptive responses to N deficiency.
Characterization of Furanocoumarin Profile and Inheritance Toward Selection of Low Furanocoumarin Seedless Grapefruit Cultivars
Authors: Chen Chunxian , Cancalon Paul , Haun Carl , Gmitter Fred
Published: January 2019

Furanocoumarins are organic chemical components in grapefruit (Citrus paradisi) juice that have been shown to induce potentially deleterious drug interactions. In this study we measured seven furanocoumarins (FCs) [bergamottin, 6′,7′-dihydroxybergamottin (6,7-DHB), paradisin C, bergaptol, isoimperatorin, 5′,8′-dimethylallyloxypsoralen (5,8-DMP), and epoxybergamottin (EBM)] in fruit of three grapefruit cultivars [Foster (Fos), Low Acid Foster (LAF), and Hudson (Hud)], one pummelo (C. maxima) cultivar [Hirado Buntan (HBP)], 17 randomly selected hybrids from HBP× Hud, and 31 other triploid hybrids. Bergamotton, 6,7-DHB, and paradisin C were not detected or extremely low in HBP (0.00, 0.11, and 0.00 mg·L−1) and LAF (0.40, 3.83, and 0.00 mg·L−1) compared with Hud (13.03. 9.58, and 6.11 mg·L−1) and Fos (6.48, 14.38, and 6.11 mg·L−1). In these hybrids, 6,7-DHB, bergamottin, and paradisin C obviously cosegregated in an approximate rate of 1:1. The three FCs in eight hybrids were not detected or extremely low, like HBP, the maternal parent; those in the other nine were as high as or higher than Hud, the paternal parent. The same segregation tendency was also observed in these triploid hybrids. Based on all the cultivars and hybrids, strong correlations existed among 6,7-DHB, bergamottin, and paradisin C (coefficient up to 0.909). Such strong correlations may reflect their metabolic links in the bergamottin pathway. The 1:1 cosegregation and strong correlation among the three FCs suggested that the trait of FCs is likely controlled by one single enzymatic or regulatory gene in the pathway. The FC profiles and inheritance may lead to a genomic and breeding solution to the grapefruit FC–drug interaction issue. Selection of FC-low or FC-free seedless grapefruit cultivars is underway.
Genetic Analysis of Walnut Cultivars in China Using Fluorescent Amplified Fragment Length Polymorphism
Authors: Ma Qingguo , Zhang Junpei , Pei Dong
Published: January 2019

Informative DNA fingerprints from 50 walnut cultivars (Juglans regia) in China were generated using amplified fragment length polymorphism (AFLP) markers to reveal their genetic diversity and relationships. Nine primer combinations were selected from 64 EcoR I/Mse I primer combinations to amplify the accessions. An average of 132 polymorphic loci per primer set was detected from the nine primer combinations. The discrimination power of each polymorphic marker (estimated by the polymorphism information content) ranged from 0.00 to 0.37 with an average of 0.19. A moderate level of genetic diversity was observed among the 50 cultivars. Their expected heterozygosity varied from 0.38 to 0.50 (average, 0.44), and Dice's similarity coefficient ranged from 0.53 to 0.86 (average, 0.70). The cluster analysis conducted using the unweighted pair group method of arithmetic averages method showed that all of the cultivars fell into five groups at Dice's similarity coefficient of 0.68. According to the comprehensive analyses based on the specific loci, similarity coefficient, and clustering results, six cultivars (Liaoning 1, Zixin, Shanhe 4, Zha 343, Tulare, and Chandler) were considered important germplasms of walnut cultivars.
Morphoanatomical Symptomatology and Osmotic Behavior of Grape Berry Shrivel
Authors: Bondada Bhaskar , Keller Markus
Published: January 2019

Berry shrivel, a physiological disorder, adversely affects ripening of grape (Vitis vinifera L.) berries; however, its causes are unknown. We adopted a holistic approach to elucidate symptomatology, morphoanatomy, and osmotic behavior of grape berry shrivel. Berries from healthy and afflicted vines were analyzed compositionally and with various techniques of microscopy. Healthy berries developed all physical and compositional attributes desirable for wine-making. Conversely, berry shrivel berries were grossly metamorphosed manifested as shriveling of the pericarp, which paralleled with loss of membrane competence in the mesocarp cells causing its collapse and a loss of brush. The most intriguing observation was the presence of non-druse crystals. These berries had high osmotic potential (ψS) as a result of low accumulations of sugar and potassium. Nonetheless, the seed morphology, structure, and viability were similar to healthy seeds. Berry shrivel grotesquely modified grape berries both compositionally and structurally, which was paralleled by their inability to accumulate sugars followed by cell death in the mesocarp. Although the mechanisms of berry shrivel remain uncertain, our study provides valuable background information for generating suitable guidelines to minimize the incidences of berry shrivel and also to design future studies toward unraveling the mechanistic basis of berry shrivel.
Influence of Substrate Water Content and Daily Light Integral on Photosynthesis, Water Use Efficiency, and Morphology of Heuchera americana
Authors: Garland Katherine F. , Burnett Stephanie E. , Day Michael E. , van Iersel Marc W.
Published: January 2019

Two investigations were conducted to determine the morphological and physiological impacts of varying light and substrate water levels on Heuchera americana ‘Dale's Strain’ (american alumroot). Both investigations used a capacitance sensor automated irrigation system to maintain constant substrate volumetric water contents (θ = volume of water/volume of substrate). In the first study, the substrate was maintained at one of eight θ ranging from 0.15 to 0.50 L·L−1. Leaf area of plants grown at the highest θ was more than twice that of plants grown at the lowest θ. Shoot dry weight also responded positively to θ increasing from 0.15 to 0.35 L·L−1, but plants did not have greater dry weights when maintained at θ higher than 0.35 L·L−1. The second experiment assessed american alumroot's performance under four daily light integrals (DLIs) (7.5, 10.8, 14.9, and 21.8 mol·m−2·d−1) with θ maintained at 0.35 L·L−1. Increasing DLI from 7.5 to 21.8 mol·m−2·d−1 caused shoot dry weight, leaf area, maximum width, and leaf count to change quadratically. Dry weight and leaf area reached their maximum at 10.8 mol·m−2·d−1, whereas leaf count was greatest at 14.9 mol·m−2·d−1. Increasing DLI to 21.8 mol·m−2·d−1 negatively impacted leaf area and leaf count but did not lower shoot dry weight. Leaf area ratio and petiole length of the uppermost fully expanded leaf decreased with increasing DLI. Measures of leaf-level net photosynthesis, light response curves, and CO2 response curves indicated no physiological differences among plants grown under different water or light levels. In both studies, long-term, whole crop measures of water use efficiency based on shoot dry weight and water applied (WUEc) did not reflect the same water use trends as instantaneous, leaf-level measures of WUE based on leaf gas exchange (WUEl). WUEc decreased with increasing θ and DLI, whereas WUEl was not influenced by θ and increased with increasing DLI. WUEl is often used to provide insight as to how various abiotic and biotic factors influence how efficiently water is used to produce biomass. However, these findings demonstrate that there are limitations associated with making such extrapolations.
Enhanced Drought Tolerance of Tobacco Overexpressing OjERF Gene Is Associated with Alteration in Proline and Antioxidant Metabolism
Authors: Li Cong , Han Lie-Bao , Zhang Xunzhong
Published: January 2019

Drought stress is one of the major limiting factors for plant growth and development. The mechanism of drought tolerance has not been well understood. This study was designed to investigate proline and antioxidant metabolism associated with drought tolerance in transgenic tobacco (Nicotiana tabacum) plants overexpressing the OjERF gene relative to wild-type (WT) plants. The OjERF gene was isolated from mondo grass (Ophiopogon japonicus). The OjERF gene, driven by the CaMV35S promoter, was introduced into tobacco through agrobacterium (Agrobacterium tumefaciens)-mediated transformation. Five transgenic lines were regenerated, of which transgenic Line 5 (GT5) and Line 6 (GT6) were used to examine drought tolerance in comparison with WT plants in a growth chamber. Drought stress caused an increase in leaf malondialdehyde (MDA) and electrolyte leakage (EL), proline content, superoxide dismutase (SOD), and catalase (CAT) activity in both transgenic lines and WT plants. However, the transgenic lines had lower MDA content and EL and higher proline content, SOD and CAT activity relative to WT under drought stress. The activities of SOD and CAT were also greater in the transgenic lines relative to WT plants under well-watered conditions (Day 0). The OjERF activated the expression of stress-relative genes, including NtERD10B, NtERD10C, NtERF5, NtSOD, and NtCAT1 in tobacco plants. The results of this study suggest that the OjERF gene may confer drought stress tolerance through upregulating proline and antioxidant metabolism.
Simple Sequence Repeat Markers from Cercis canadensis Show Wide Cross-species Transfer and Use in Genetic Studies
Authors: Wadl Phillip A. , Trigiano Robert N. , Werner Dennis J. , Pooler Margaret R. , Rinehart Timothy A.
Published: January 2019

There are 11 recognized Cercis L. species, but identification is problematic using morphological characters, which are largely quantitative and continuous. Previous studies have combined morphological and molecular data to resolve taxonomic questions about geographic distribution of Cercis species, identifying botanical varieties, and associations between morphological variation and the environment. Three species have been used in ornamental plant breeding in the United States, including three botanical varieties of C. canadensis L. from North America and two Asian species, C. chingii Chun and C. chinensis Bunge. In this article, 51 taxa were sampled comprising eight species of Cercis and a closely related species, Bauhinia faberi Oliv. Sixty-eight polymorphic simple sequence repeat markers were used to assess genetic relationships between species and cultivars. For all samples the number of alleles detected ranged from two to 20 and 10 or more alleles were detected at 22 loci. Average polymorphic information content was 0.57 and values ranged from 0.06 to 0.91 with 44 loci 0.50 or greater. Cross-species transfer within Cercis was extremely high with 55 loci that amplified at 100%. Results support previously reported phylogenetic relationships of the North American and western Eurasian species and indicate suitability of these markers for mapping studies involving C. canadensis and C. chinensis. Results also support known pedigrees from ornamental tree breeding programs for the widely cultivated C. canadensis and C. chinensis species, which comprised the majority of the samples analyzed.
Enhanced Visualization of the Fine Structure of the Stigmatic Surface of Citrus using Pre-fixation Washes
Authors: Wetzstein Hazel Y. , Law S. Edward
Published: January 2019

Stigma characteristics and morphology can be useful in taxonomic and phylogenetic studies, indicate relationships in stigma function and receptivity, and be valuable in evaluating pollen–stigma interactions. Problematic is that in some taxa, copious stigmatic exudate can obscure the fine structural details of the stigmatic surface. Such is the case for Citrus, which has a wet stigma type on which abundant exudate inundates surface papillae. The components of stigmatic surface compounds are highly heterogeneous and include carbohydrates, proteins, lipids, glycoproteins, and phenolic compounds. This study evaluated the efficacy of several pre-fixation wash treatments on removing surface exudate to visualize the underlying stigmatic surface. Wash treatments included various buffer solutions, surfactants, dilute acids/bases, and solvents. Stigmas prepared using conventional fixation methods in glutaraldehyde had considerable accumulations of reticulate surface deposits with stigmatic cells obscured. Pre-fixation washes containing solvents such as methanol, chloroform, and ethanol left accumulations of incompletely removed exudate and crystalline deposits. Alkaline water washes produced a crust-like deposit on stigma surfaces. Buffer washes left residues of plaque-like deposits with perforated areas. In contrast, excellent removal of stigmatic exudate was obtained with a pre-fixation wash composed of 0.2 M Tris buffer, pH 7.2, containing 0.2% Triton X-100 surfactant and allowed clear imaging of the stigma and surface papillae morphology. A central sinus and radially arranged openings on the stigmatic surface were clearly visible and shown for the first time using scanning electron microscopy (SEM).
Response of Cell Division and Cell Expansion to Local Fruit Heating in Tomato Fruit
Authors: Fanwoua Julienne , de Visser Pieter , Heuvelink Ep , Angenent Gerco , Yin Xinyou , Marcelis Leo , Struik Paul
Published: January 2019

To improve our understanding of fruit growth responses to temperature, it is important to analyze temperature effects on underlying fruit cellular processes. This study aimed at analyzing the response of tomato (Solanum lycopersicum) fruit size to heating as affected by changes in cell number and cell expansion in different directions. Individual trusses were enclosed into cuvettes and heating was applied either only during the first 7 days after anthesis (DAA), from 7 DAA until fruit maturity (breaker stage), or both. Fruit size and histological characteristics in the pericarp were measured. Heating fruit shortened fruit growth period and reduced final fruit size. Reduction in final fruit size of early-heated fruit was mainly associated with reduction in final pericarp cell volume. Early heating increased the number of cell layers in the pericarp but did not affect the total number of pericarp cells. These results indicate that in the tomato pericarp, periclinal cell divisions respond differently to temperature than anticlinal or randomly oriented cell divisions. Late heating only decreased pericarp thickness significantly. Continuously heating fruit reduced anticlinal cell expansion (direction perpendicular to fruit skin) more than periclinal cell expansion (direction parallel to fruit skin). This study emphasizes the need to measure cell expansion in more than one dimension in histological studies of fruit.
Mapping of the Egusi Seed Trait Locus (eg) and Quantitative Trait Loci Associated with Seed Oil Percentage in Watermelon
Authors: Prothro Jason , Sandlin Katherine , Gill Rattandeep , Bachlava Eleni , White Victoria , Knapp Steven J. , McGregor Cecilia
Published: January 2019

The egusi watermelon (Citrullus lanatus) is popular in West Africa for its oil and protein-rich seed, which is consumed in soups and stews. The egusi phenotypic trait is controlled by a single recessive gene (eg) and is characterized by large seed size and fleshy, thick pericarp. An F2 mapping population was derived from Strain II (PI 279461) of the Japanese cultivar Yamato-cream with normal seed type and low seed oil percentage (SOP = 25.2%) and an egusi type from Nigeria [Egusi (PI 560023)] with high SOP (40.6%). Genetic analysis confirmed that the egusi seed trait is controlled by a single recessive gene (eg) and the location of the gene was mapped to 57.8 cM on linkage group (LG) 2, between markers NW0248325 and NW0250248. Four main quantitative trait loci (M-QTL) were identified for SOP in the population with the eg locus contributing 84% of the explained phenotypic variation (R2). A significant epistatic interaction (E-QTL) was identified between, the eg locus and an M-QTL on LG 9B. The present study reports the location of the eg locus responsible for the egusi seed trait in watermelon on LG 2 as well as M-QTL and E-QTL associated with SOP.
Identification of “Duplicate” Accessions within the USDA-ARS National Plant Germplasm System Malus Collection
Authors: Gross Briana L. , Volk Gayle M. , Richards Christopher M. , Forsline Philip L. , Fazio Gennaro , Chao C. Thomas
Published: January 2019

The U.S. Department of Agriculture, Agricultural Research Service, National Plant Germplasm System (NPGS), Plant Genetic Resources Unit apple (Malus) collection in Geneva, NY, conserves over 2500 trees as grafted clones. We have compared the genotypes of 1131 diploid Malus ×domestica cultivars with a total of 1910 wild and domesticated samples representing 41 taxonomic designations in the NPGS collection to identify those that are genetically identical based on nine simple sequence repeat (SSR) loci. We calculated the probability of identity for samples in the data set based on allelic diversity and, where possible, use fruit images to qualitatively confirm similarities. A total of 237 alleles were amplified and the nine SSRs were deemed adequate to assess duplication within the collection with the caveat that “sport families” likely would not be differentiated. A total of 238 M. ×domestica and 10 samples of other taxonomic groups shared a genotype with at least one other M. ×domestica individual. In several cases, genotypes for cultivars matched genotypes of known rootstocks and indicated that these accessions may not accurately represent the indicated named clones. Sets of individuals with identical genotypes and similar cultivar names were assigned to sport families. These 23 sport families, comprised of 104 individuals, may have mutational differences that were not identified using the nine SSR loci. Five of the selected markers (CH01h01, CH02d08, CH01f02, G12, GD147) overlap with sets of markers that have been used to fingerprint European apple collections, thus making it possible to compare and coordinate collection inventories on a worldwide scale.
Biotypic Diversity and Resistance to the Raspberry Aphid Amphorophora agathonica in Pacific Northwestern North America
Authors: Dossett Michael , Kempler Chaim
Published: January 2019

Resistance to colonization by the raspberry aphid (Amphorophora agathonica Hottes) has been an important objective in North American red raspberry (Rubus idaeus L.) breeding programs since the 1930s because of its effectiveness in controlling the spread of aphid-transmitted viruses in red raspberry. The most widely used source of resistance in North America has been the gene Ag1 from ‘Lloyd George’. The widespread use of Ag1 to control aphids led to the appearance of a resistance-breaking biotype in British Columbia, Canada, in 1990. Our objective was to identify biotypes of A. agathonica present in the commercial red raspberry production region of southwestern British Columbia and northwestern Washington and determine what sources of resistance may still be effective against this pest. We collected 12 aphid isolates and screened them against 15 raspberry cultivars and four selections. Although it has been widely believed that only two biotypes (regular and Ag1-breaking) of A. agathonica were present in the region, we identified six distinct biotypes and characterized them by their ability or inability to colonize a differential set of raspberry cultivars. This has confirmed the loss of previously recognized and unrecognized sources of resistance in some cultivars. The data also support the presence of a seventh biotype that has not yet been observed. In addition, we confirmed resistance from three sources of wild North American red raspberries that hold up to each of these biotypes. Our results will serve as a guide for future efforts to characterize the prevalence of different aphid biotypes in the region and the identification of new sources of resistance for breeding.
Life Cycle Assessment to Study the Carbon Footprint of System Components for Colorado Blue Spruce Field Production and Use
Authors: Ingram Dewayne L.
Published: January 2019

The contributions of interrelated production system components of a field-grown, 2-m-tall, 5-cm-caliper Picea pungens (colorado blue spruce) in the upper midwestern (liner) and lower midwestern (finished tree) regions of the United States to its carbon footprint were analyzed using life cycle assessment protocols. The seed-to-landscape carbon footprint was 13.558 kg carbon dioxide equivalent (CO2e), including sequestration of 9.14 kg CO2e during production. The global warming potential (GWP) from equipment use was the dominant contributor to the carbon footprint of production. Seventy-six percent of the GWP investments during field production occurred at harvest. Querying the model, among other things, revealed that adding one year to the field production phase would add less than 3% to the seed-to-landscape GWP of the product. The weighted positive impact of carbon (C) sequestration during a 50-year life was 593 kg CO2e. After its useful life, takedown and disposal would result in emissions of 148 kg CO2e, resulting in a net positive, life cycle impact on atmospheric CO2 of ≈431 kg CO2e.
Increases in Shoot Tissue Pigments, Glucosinolates, and Mineral Elements in Sprouting Broccoli after Exposure to Short-duration Blue Light from Light Emitting Diodes
Authors: Kopsell Dean A. , Sams Carl E.
Published: January 2019

Microgreens are specialty leafy crops harvested just above the roots after the first true leaves have emerged and are consumed fresh. Broccoli (Brassica oleacea var. italica) microgreens can accumulate significant concentrations of cancer-fighting glucosinolates as well as being a rich source of other antioxidant phytochemicals. Light-emitting diodes (LEDs) now provide the ability to measure impacts of narrow-band wavelengths of light on seedling physiology. The carotenoid zeaxanthin has been hypothesized to be a blue light receptor in plant physiology. The objective of this study was to measure the impact of short-duration blue light on phytochemical compounds, which impart the nutritional quality of sprouting broccoli microgreens. Broccoli microgreens were grown in a controlled environment under LEDs using growing pads. Seeds were cultured on the pads submerged in deionized water and grown under a 24-hour photoperiod using red (627 nm)/blue (470 nm) LEDs (350 μmol·m−2·s−1) at an air temperature of 23 °C. On emergence of the first true leaf, a complete nutrient solution with 42 mg·L−1 of nitrogen (N) was used to submerge the growing pads. At 13 days after sowing, broccoli plantlets were grown under either: 1) red and blue LED light (350 μmol·m−2·s−1); or 2) blue LED light (41 μmol·m−2·s−1) treatments for 5 days before harvest. The experiment was repeated three times. Frozen shoot tissues were freeze-dried and measured for carotenoids, chlorophylls, glucosinolates, and mineral elements. Comparing the two LED light treatments revealed the short-duration blue LED treatment before harvest significantly increased shoot tissue β-carotene (P ≤ 0.05), violaxanthin (P ≤ 0.01), total xanthophyll cycle pigments (P ≤ 0.05), glucoraphanin (P ≤ 0.05), epiprogoitrin (P ≤ 0.05), aliphatic glucosinolates (P ≤ 0.05), essential micronutrients of copper (Cu) (P = 0.02), iron (Fe) (P ≤ 0.01), boron (B), manganese (Mn), molybdenum (Mo), sodium (Na), zinc (Zn) (P ≤ 0.001), and the essential macronutrients of calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), and sulfur (S) (P ≤ 0.001). Results demonstrate management of LED lighting technology through preharvest, short-duration blue light acted to increase important phytochemical compounds influencing the nutritional value of broccoli microgreens.
Nuclear DNA Content, Base Composition, and Cytogenetic Characterization of Christia obcordata
Authors: Sakhanokho Hamidou F. , Islam-Faridi Nurul
Published: January 2019

Christia obcordata is an intriguing small-sized house plant with unusual and attractive features such as its striped leaves. Because very little is known about the plant, we conducted an investigation of its genome and chromosomes. The number of chromosomes was determined using a protoplast technique to prepare root tip chromosome spread and was found to be 2n = 2x = 20. Flow cytometry was used to determine nuclear DNA content (1C = 0.65 pg = 634.4 Mb) for C. obcordata and AT/GC composition was shown to be AT% = 62.8% ± 0.0% and GC% = 37.2% ± 0.0%. Finally, fluorescent in situ hybridization was used to locate ribosomal RNA gene families in C. obcordata. Ribosomal RNA gene families, viz. 18S-28S and 5S rDNA, are unique cytomolecular landmarks that provide valuable information about the evolutionary organization of a genome. We have identified one locus each of 18S-28S and 5S rDNA. The 18S-28S rDNA is located in the subterminal position on the secondary constriction region [also known as the nucleolus organizer region (NOR)] and the 5S rDNA is located interstitially close to a centromeric position. The basic information gathered in this study on C. obcordata will be helpful in understanding the genetics of this species.
The Uptake and Partitioning of Nitrogen in Phalaenopsis Sogo Yukidian ‘V3’ as Shown by 15N as a Tracer
Authors: Susilo Hadi , Peng Ying-Chun , Lee Shui-Cheng , Chen Yu-Chun , Alex Chang Yao-Chien
Published: January 2019

Phalaenopsis is currently the world’s number one potted flower crop. It is a slow-growing plant that responds slowly to nitrogen (N) fertilization and is noted for great resilience against N deficiency. Despite the great significance of N during the cultivation of Phalaenopsis, little has been studied on the uptake and partitioning of N in this crop. The stable isotope 15N was used as a tracer to investigate the uptake and partitioning of N and the roles of organs in sink and source relationship of N partitioning during different stages in Phalaenopsis. Fertilizer labeled with 15N was applied to Phalaenopsis Sogo Yukidian ‘V3’ during the vegetative growth stage on different parts of plants. Both leaves and roots were able to take up N. Nitrogen uptake efficiency of young roots was the highest, followed by old roots, whereas that of leaves was lowest. No difference of N uptake efficiency was found between the upper and lower leaf surfaces. Movement of fertilizer N to the leaves occurred as early as 0.5 day after fertilizer application to the roots. The partitioning of N depended on organ sink strength. During the vegetative growth stage, newly grown leaves and newly formed roots were major sinks. Sink strength of leaves decreased with the increase in leaf age. Stalks and flowers were major sinks during the reproductive growth stage. Mature leaves were a major location where N was stored and could serve as a N source during the reproductive growth stage and also for new leaf growth.