bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Tomatoes Expressing Anthocyanin in the Fruit
Authors: Mes Peter J. , Boches Peter , Myers James R. , Durst Robert
Published: January 2019

Cultivated tomatoes (Solanum lycopersicum L.) produce anthocyanins in vegetative tissues and certain flavonols can be found in the fruit. Some related wild species do produce anthocyanins in the fruit, and this trait has been transferred into cultivated tomato. Fruit with the genes Abg, Aft, and atv exhibit varying degrees of anthocyanin production in the epidermis, but not in the fruit pericarp. Fruit with these alleles in various combinations were analyzed to characterize the anthocyanidin profile, moieties, and total anthocyanin content. In general, combining atv with either Aft or Abg substantially increased anthocyanin production in the fruit. Over 23 different anthocyanins were detected, petunidin-3-(p-coumaryl)-rutinoside-5-glucoside being predominant. The highest level of anthocyanin expression was observed in small fruit with the genotype Abg- atvatv and AftAft atvatv, well in excess of 100 mg/100 g fresh weight of epidermis and subepidermis depending on the size of the fruit. Nonanthocyanin flavonoids were also upregulated in proportion to the anthocyanin concentration. The anthocyanin genes were also combined with genes affecting carotenoid composition and content. Reduced carotenoid content conditioned by the alleles B (Beta) and r (yellow flesh) was associated with lower total anthocyanins, an unexpected observation because the carotenoid and anthocyanin pathways are thought to be independent. The level of anthocyanin did not affect carotenoid profiles or amounts.
Photosynthetic Responses to Sink–Source Manipulation in Five Peach Cultivars Varying in Maturity Date
Authors: Wu Ben Hong , Huang Hai Qiang , Fan Pei Ge , Li Shao Hua , Liu Guo Jie
Published: January 2019

Five peach cultivars [Prunus persica (L.) Batch] with different maturity dates were subjected to sink–source manipulation by girdling to isolate 1-year-old fruit-bearing shoots. Four treatments were performed: fruit were removed (−fruit); one fruit (+1 fruit) and two fruit (+2 fruit) were kept inside two girdling cuts; and two fruit were kept outside two girdling cuts (−fruit*). Photosynthetic responses for the five cultivars were similar and did not show genotypic differences. Generally, net photosynthetic rate (Pn), stomatal conductance (g
s), and transpiration rate (E) were higher, and leaf temperature (Tl) was lower in +2 fruit than in +1 fruit, followed by −fruit and −fruit* which were not different. The results also indicated that water outflow from fruit into leaves did not influence photosynthesis, and lower photosynthesis in −fruit treatment was not due to water status of source leaves influenced by removing fruit. Pn tended to increase with Tl until Tl reached a critical level. Beyond the critical temperature level, Pn generally decreased. The critical Tl was roughly identified as 34–37 °C for the five cultivars. Both higher and lower substomatal CO2 (Ci) levels occurred in −fruit and −fruit* treatments than in +1 fruit and +2 fruit treatments, indicating that decreased Pn could be due to both nonstomatal and stomatal limitations. Further analysis of the relationship between Ci and photosynthetically active radiation (PAR) showed that nonstomatal limitation under low sink demand took place mostly under high PAR. Thus, high light intensity, combined with Tl may play an important role in leaf photosynthetic regulation.
Influence of Microgravity Environment on Root Growth, Soluble Sugars, and Starch Concentration of Sweetpotato Stem Cuttings
Authors: Mortley Desmond G. , Bonsi Conrad K. , Hill Walter A. , Morris Carlton E. , Williams Carol S. , Davis Ceyla F. , Williams John W. , Levine Lanfang H. , Petersen Barbara V. , Wheeler Raymond M.
Published: January 2019

Because sweetpotato [Ipomoea batatas (L.) Lam.] stem cuttings regenerate very easily and quickly, a study of their early growth and development in microgravity could be useful to an understanding of morphological changes that might occur under such conditions for crops that are propagated vegetatively. An experiment was conducted aboard a U.S. Space Shuttle to investigate the impact of microgravity on root growth, distribution of amyloplasts in the root cells, and on the concentration of soluble sugars and starch in the stems of sweetpotatoes. Twelve stem cuttings of ‘Whatley/Loretan’ sweetpotato (5 cm long) with three to four nodes were grown in each of two plant growth units filled with a nutrient agarose medium impregnated with a half-strength Hoagland solution. One plant growth unit was flown on Space Shuttle Columbia for 5 days, whereas the other remained on the ground as a control. The cuttings were received within 2 h postflight and, along with ground controls, processed in ≈45 min. Adventitious roots were counted, measured, and fixed for electron microscopy and stems frozen for starch and sugar assays. Air samples were collected from the headspace of each plant growth unit for postflight determination of carbon dioxide, oxygen, and ethylene levels. All stem cuttings produced adventitious roots and growth was quite vigorous in both ground-based and flight samples and, except for a slight browning of some root tips in the flight samples, all stem cuttings appeared normal. The roots on the flight cuttings tended to grow in random directions. Also, stem cuttings grown in microgravity had more roots and greater total root length than ground-based controls. Amyloplasts in root cap cells of ground-based controls were evenly sedimented toward one end compared with a more random distribution in the flight samples. The concentration of soluble sugars, glucose, fructose, and sucrose and total starch concentration were all substantially greater in the stems of flight samples than those found in the ground-based samples. Carbon dioxide levels were 50% greater and oxygen marginally lower in the flight plants, whereas ethylene levels were similar and averaged less than 10 nL·L−1. Despite the greater accumulation of carbohydrates in the stems, and greater root growth in the flight cuttings, overall results showed minimal differences in cell development between space flight and ground-based tissues. This suggests that the space flight environment did not adversely impact sweetpotato metabolism and that vegetative cuttings should be an acceptable approach for propagating sweetpotato plants for space applications.
Isotopic Labeling of Red Cabbage Anthocyanins with Atmospheric 13CO2
Authors: Charron Craig S. , Britz Steven J. , Mirecki Roman M. , Harrison Dawn J. , Clevidence Beverly A. , Novotny Janet A.
Published: January 2019

Isotopic labeling of plants provides a unique opportunity for understanding metabolic processes. A significant challenge of isotopic labeling during plant growth is that isotopes must be administered without disrupting plant development and at sufficient levels for mass spectral analysis. We describe a system for isotopic labeling of leafy vegetables with 13C and demonstrate successful incorporation of 13C into anthocyanins of preheading red cabbage (Brassica oleracea L. var. capitata L.). ‘Super Red’ red cabbage seedlings were grown for 34 days in an airtight acrylic labeling chamber supplied with 13CO2 to maintain 400 μL·L−1. Nutrient solution was delivered hydroponically without allowing infusion of natural CO2 into the labeling chamber. Plants were initially grown at 22 °C ± 1 °C in constant light of 228 μmol·m−2·s−1. Upon canopy closure, anthocyanin development was promoted by reducing the nutrient solution concentration and reducing the temperature to 10.5 °C ± 1.5 °C. Total shoot fresh weight (FW) was 1556 g and root FW was 491 g at harvest. Analysis of red cabbage shoot tissue by high-performance liquid chromatography/tandem mass spectrometry indicated the presence of 37 anthocyanins, of which 14 are reported here for the first time. Mass shifts representing 13C incorporation into anthocyanins were evident in mass spectra of anthocyanins from labeled tissue and demonstrate successful isotopic labeling.
Antioxidant Responses of Radiation-induced Dwarf Mutants of Bermudagrass to Drought Stress
Authors: Lu Shaoyun , Wang Zhongcheng , Niu Yuejing , Guo Zhenfei , Huang Bingru
Published: January 2019

Improving the drought tolerance of widely used bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon] is important for water conservation and producing quality turf with limited irrigation. Mutants of bermudagrass were generated using gamma-ray irradiation with an aim toward developing dwarf and drought-resistant bermudagrass. The objectives of this study were to compare morphological characteristics between radiation-induced mutants and the wild-type of bermudagrass and to determine antioxidant responses associated with changes in drought resistance in the bermudagrass mutants. Three mutant lines (7-9, 10-5, and 10-12) that exhibit slow growth and good turf quality were chosen for this study. Plants were exposed to drought stress by withholding irrigation in a greenhouse. Mutant lines had lower canopy height, shorter internodes, and shorter leaves than the wild type under well-watered conditions. Under drought stress, all three dwarf mutant lines maintained higher relative water content and lower ion leakage and malondialdehyde content than the wild type. Antioxidant enzyme activities decreased in response to the drought stress in the mutant lines and the wild type, whereas nonenzymatic antioxidants increased under drought stress. Compared with the wild type, higher enzyme activities and antioxidant contents were maintained in mutant lines under drought stress. Our results indicated that bermudagrass mutants induced by gamma radiation exhibited dwarf characteristics and improved drought resistance, which was associated with maintenance of higher levels of antioxidant enzyme activities and nonenzymatic antioxidant contents.
Expansin and XET Genes Are Differentially Expressed During Aril Breakdown in Harvested Longan Fruit
Authors: Zhong Yu-Xiong , Chen Jian-Ye , Feng Hai-Ling , Kuang Jian-Fei , Xiao Ruo , Ou Min , Xie Hui , Lu Wang-Jin , Jiang Yue-Ming , Lin He-Tong
Published: January 2019

Fresh fruit of longan (Dimocarpus longan Lour.) are susceptible to pericarp browning and aril breakdown. Aril breakdown in longan fruit is regarded as one of the most important factors reducing quality and shortening storage life of the fruit. To better understand the molecular mechanism of aril breakdown, the expression patterns of three expansin (EXP) and three xyloglucan endotransglucosylase (XET) genes in relation to the aril breakdown of longan fruit stored at room temperature (25 °C) or low temperature (4 °C) were investigated. The results showed that aril breakdown index increased progressively during storage at 25 and at 4 °C. Northern blotting analysis revealed that the accumulations of three EXP and three XET genes exhibited differential characteristics with the occurrence of aril breakdown. During storage at 25 °C, the accumulations of Dl-XET3 increased after 1 day, suggesting that Dl-XET3 correlated well with the early aril breakdown, while Dl-EXP3 together with Dl-XET1 and Dl-XET2 was involved in later aril breakdown. However, expression of Dl-XET1 and Dl-XET2 could be mainly involved in aril breakdown of longan fruit stored at 4 °C. In addition, Dl-EXP2, whose accumulation increased sharply when longan fruit were transferred from low temperature to room temperature within 12 hours, was related to the aril breakdown in this storage period. These data indicated that Dl-EXPs and Dl-XETs were closely related to aril breakdown in longan fruit.
Use of SSR Markers to Assess Identity, Pedigree, and Diversity of Cultivated Muscadine Grapes
Authors: Riaz Summaira , Tenscher Alan C. , Smith Brady P. , Ng Daniel A. , Walker M. Andrew
Published: January 2019

The North American muscadine grape (Muscadinia rotundifolia Small) is a valuable source of resistance to powdery mildew [Uncinula necator (Schw.) Burr], root-knot nematode (Meloidogyne Goeldi), dagger nematode (Xiphinema index Thorne and Allen), grape phylloxera (Daktulosphaira vitifoliae Fitch), and Pierce's disease (Xylella fastidiosa Wells et al.). Efforts to breed muscadine grapes commenced in the early 1900s and have generated a large number of cultivars and a limited number of hybrids with Vitis vinifera L. and other Vitis L. species. Collections of this germplasm are currently maintained with accession identity based on declared identity when collected, breeding records, and comparisons of morphological traits. This study reports on the first use of DNA-based simple sequence repeat (SSR) marker profiles to authenticate M. rotundifolia cultivars and hybrids. A total of 57 accessions [39 M. rotundifolia cultivars, 3 V. vinifera cultivars, 3 Vitis spp. hybrids, and 12 V. vinifera × M. rotundifolia (VR) hybrids] from collections at the U.S. Department of Agriculture National Clonal Germplasm Repository and the University of California (Davis) Department of Viticulture and Enology were analyzed with 14 SSR markers. The fingerprint profiles were used to verify published breeding records of 31 M. rotundifolia cultivars and hybrids by comparing the shared alleles of parents and progeny. Marker data indicated that four cultivars were incorrectly identified; their alleles did not match respective parent/progeny relationships at more than five loci. Two M. rotundifolia accessions had the same fingerprint profile as a third accession at all 14 markers, implicating a likely planting error. The M. rotundifolia cultivars exhibited 88 unique alleles that were not present in a database of more than 600 V. vinifera cultivars.
Molecular Characterization of Mulberry Accessions in Turkey by AFLP Markers
Authors: Kafkas Salih , Özgen Mustafa , Doğan Yıldız , Özcan Burcu , Ercişli Sezai , Serçe Sedat
Published: January 2019

Mulberries (Morus L.) show a great deal of genetic variability and adaptability to various environments. There are more than 24 species of mulberries in cultivated and wild forms. In Turkey, three Morus species, M. alba L., M. nigra L., and M. rubra L., are grown. In this study, we attempted to characterize 43 Morus accessions originating from distinct regions of Turkey using fluorescent dye amplified fragment length polymorphism (AFLP) markers and capillary electrophoresis. The accessions belonged to M. alba, M. nigra, and M. rubra; M. alba consisted of white- and purple-fruited samples. Eight primer combinations generated a total of 416 bands, 337 of which were polymorphic (80.5%). Resolving powers of the AFLP primers ranged from 0.410 to 0.942 making a total of 5.015, whereas the polymorphic information content ranged from 0.662 to 0.898 with an average of 0.812. Unweighted pair-group method of arithmetic mean (UPGMA) clustering of the accessions showed three major groups representing M. nigra, M. rubra, and M. alba accessions. The M. alba group had two subgroups that were not correlated with fruit color. The UPGMA dendrogram of average taxonomic differences confirmed these results. The principle coordinate analysis demonstrated that M. nigra accessions had limited genetic variation. In conclusion, our study indicated that M. nigra and M. rubra are molecularly distinct from M. alba. Our results also suggest that M. nigra accessions having a low level of morphological variation are molecularly similar.
Assessment of the Tuscan Olive Germplasm by Microsatellite Markers Reveals Genetic Identities and Different Discrimination Capacity among and within Cultivars
Authors: Cantini Claudio , Cimato Antonio , Autino Antonella , Redi Alessandro , Cresti Mauro
Published: January 2019

Microsatellite markers were used to characterize the accessions in the Tuscan olive (Olea europaea L.) germplasm collection. One hundred fifty-four genotypes were considered for genetic fingerprinting using 12 pairs of microsatellite primers. Investigation was focused on genotypes with similar morphologies and clones of the same cultivar from different agroecological areas within Tuscany. All 12 primer pairs produced microsatellite fragments for all the accessions amplifying from three to 10 alleles with a mean of 5.7 alleles/locus. The discovery of 30 synonyms and several misnames set the final number of genotypes representing the whole germplasm collection at 79. For Frantoio, Leccino, and Pendolino, no intracultivar diversity was found, although Leccino was known to have morphological distinction. Heterozygosity levels for the loci ranged from 0.287 to 0.722 with a mean value of 0.524. Some accessions presenting small differences in fingerprinting with similarity index greater than 0.87 were morphologically indistinguishable. The study demonstrates that for the management of the olive germplasm collection, it is necessary to use the morphological information in addition to the fingerprint when dealing with accessions presenting a microsatellite profile with high similarity index; otherwise, the risk is to overestimate the diversity among cultivars or presumed cultivars and to underestimate the one diversity already present within the cultivars.
Density and Duration of Shade Affect Water and Nutrient Use in Greenhouse Tomato
Authors: Gent Martin P.N.
Published: January 2019

Shading a greenhouse may have a time-dependent effect on fruit production and water and nutrient uptake in tomato plants (Solanum lycopersicum L.) as a result of acclimation to light and a dependence on stored carbohydrate and nutrients. In 2 years in the northeastern United States, shadecloth was applied at the start of warm weather in June and the houses were shaded until late August. Simultaneous comparisons were made among greenhouse sections that were either not shaded or covered with reflective aluminized shadecloth that blocked 0.15, 0.30, or 0.50 of direct sunlight. The amounts of water, nitrogen, and potassium taken up per day were calculated for successive 3-week intervals after shade was applied. The effect of shade on these uptake rates was compared with the effect on the rate of fruit production. There was a linear decline in water, nitrogen, and potassium uptake with increasing shade density. In each 3-week interval, water uptake under 0.5 shade density was 25% and 20% less than under no shade in 2004 and 2005, respectively. The uptake of nitrogen and potassium uptake under 0.5 shade density was ≈25% less than that under no shade. Shading did not affect the rate of fruit production within 3 weeks of application, but after more than 6 weeks, it was 30% less under 0.5 shade density than under no shade. The use efficiencies of radiation, water, and nutrients for fruit production increased with shade density immediately after shade were applied. These effects of shade on apparent resource use efficiencies dissipated from 3 to 6 weeks after shade was applied, because the effect of shade density on fruit production became proportionally the same as the effects on water and nutrient uptake. The water and nutrient uptake of greenhouse tomato acclimated to the change in irradiance resulting from shade within 3 weeks, but the full effect of shade on fruit production was not seen until 6 weeks after the application of shade.
Responses of Growth and Ion Uptake of Four Rose Rootstocks to Chloride- or Sulfate-dominated Salinity
Authors: Niu Genhua , Rodriguez Denise S.
Published: January 2019

Salt-tolerant garden roses (Rosa L.) are needed for arid and semiarid regions where high-quality water supply is limited and soil salinization often occurs. This greenhouse study evaluated growth, ion uptake characteristics, and the daily evapotranspiration rate (ET) of four rose rootstocks [‘Dr. Huey’ (Rosa ×hybrida L.), R. ×fortuniana Lindl., R. multiflora Thunb., and R. odorata (Andr.) Sweet] irrigated with saline solutions with chloride or sulfate as the dominant salts. After 16 weeks of treatment, the elevated salinities reduced growth of all rootstocks, but the magnitude varied with the rootstock and dominant salt type. At moderate [3.9 dS·m−1 electrical conductivity (EC)] and high salinities (7.9 to 8.2 dS·m−1), chloride-dominated salinity led to a greater growth reduction in R. × fortuniana, followed by R. odorata and R. multiflora. At high salinity dominated by sulfate, R. odorata had a greater growth reduction, followed by R. multiflora, ‘Dr. Huey’, and R. ×fortuniana. For R. multiflora, growth was reduced more in chloride-dominated salinity at high salinity levels, but no differences were found in the growth between the two salt types at moderate salinity. Rosa multiflora accumulated more Na than R. odorata, and R. ×fortuniana accumulated the least. However, R. multiflora retained most the Na in the roots, whereas R. odorata transported 57% of the Na to shoots. All rootstocks had a similar high leaf Cl concentration at high salinity dominated by chloride, while R. ×fortuniana had the most severe foliar salt damage, indicating that R. ×fortuniana had a lower threshold concentration of tissue Cl. At moderate salinity, all rootstocks had acceptable visual quality. At high salinity, the appearance of all rootstocks declined with typical salt damage on lower, older leaves, and the plants had lower visual scores in chloride-dominated salinity, especially in R. ×fortuniana. Salinity treatment did not affect the daily ET per unit leaf area, regardless of rootstock and dominant salt type. Daily ET per pot was the smallest in R. ×fortuniana among the four rootstocks due to its smaller total leaf area. The four rootstocks responded differently to salinity and dominant salt type.
Gibberellic Acid Alters Sucrose, Hexoses, and Their Gradients in Peel Tissues During Color Break Delay in ‘Hamlin’ Orange
Authors: Fidelibus Matthew W. , Koch Karen E. , Davies Frederick S.
Published: January 2019

We investigated the effect of gibberellic acid (GA3) application before color break on peel color, fruit respiration, and soluble sugars in different tissues of ‘Hamlin’ sweet orange [Citrus sinensis (L.) Osb.] fruit to test the hypothesis that GA3 influence on peel color might be mediated by sugars. Fruit were sprayed with GA3 (45 g·ha−1 a.i.) in early October of 2 consecutive years. Peel color, whole-fruit respiration, and fructose, glucose, and sucrose levels were quantified in flavedo and albedo tissues when nontreated fruit were still green, at precolor break, color break, and when peels were fully yellow. Fruit treated with GA3 remained more green-colored than nontreated fruit, and differences between them were detectable by 12 or 21 days after treatment (Years 1 and 2, respectively). Fruit respiration rates were similar in both groups regardless of peel color. Effects of GA3 on color transition were evident only after significant differences emerged in flavedo glucose (both years) and fructose (second year) levels. Moreover, there was a linear, inverse relationship between green peel color and flavedo fructose (r
2 = 0.68, first year; 0.72, second year) and glucose levels (r
2 = 0.60, first year; 0.50, second year). In contrast, sucrose levels in the flavedo showed a less consistent relationship with peel color. The GA3 treatment maintained a descending sucrose gradient from the albedo to the flavedo that was typical of young, photosynthetically active fruit. This gradient dissipated during peel color change of nontreated fruit. These data support the hypothesis that soluble sugars could be contributing effectors of the GA3-mediated delay in chloroplast-to-chromoplast conversions by the orange flavedo.
Structural Adaptations in Overwintering Leaves of Thermonastic and Nonthermonastic Rhododendron Species
Authors: Wang Xiang , Arora Rajeev , Horner Harry T. , Krebs Stephen L.
Published: January 2019

Evergreen rhododendrons (Rhododendron L.) are important woody landscape plants in many temperate zones. During winters, leaves of these plants frequently are exposed to a combination of cold temperatures, high radiation, and reduced photosynthetic activity, conditions that render them vulnerable to photooxidative damage. In addition, these plants are shallow-rooted and thus susceptible to leaf desiccation when soils are frozen. In this study, the potential adaptive significance of leaf morphology and anatomy in two contrasting Rhododendron species was investigated. R. catawbiense Michx. (native to eastern United States) exhibits thermonasty (leaf drooping and curling at subfreezing temperatures) and is more winter-hardy [leaf freezing tolerance (LT50) of containerized plants ≈–35 °C], whereas R. ponticum L. (native to central Asia) is less hardy (LT50 ≈–16 °C), and nonthermonastic. Thermonasty may function as a light and/or desiccation avoidance strategy in rhododendrons. Microscopic results revealed that R. ponticum has significantly thicker leaf blades but thinner cuticle than R. catawbiense. There is one layer of upper epidermis and three layers of palisade mesophyll in R. catawbiense compared with two distinct layers of upper epidermis and two layers of palisade mesophyll in R. ponticum. We suggest that the additional layer of upper epidermis in R. ponticum and thicker cuticle and extra palisade layer in R. catawbiense represent structural adaptations for reducing light injury in leaves and could serve a photoprotective function in winter when leaf photochemistry is generally sluggish. Results also indicate that although stomatal density of R. ponticum is higher than that of R. catawbiense leaves, the overall opening of stomatal pores per unit leaf area (an integrated value of stomatal density and pore size) is higher by approximately twofold in R. catawbiense, suggesting that R. catawbiense may be more prone to winter desiccation and that thermonasty may be a particularly beneficial trait in this species by serving as a desiccation-avoidance strategy in addition to a photoprotection role.
Reciprocal Differences in Sugary × Sugary Enhancer Sweet Corn Hybrids
Authors: Ordás Bernardo , Malvar Rosa A. , Ordás Amando , Revilla Pedro
Published: January 2019

Reciprocal effects in sugary × sugary enhancer hybrids of sweet corn (Zea mays L.) have been only reported for sugar content and in a very limited number of hybrids and have not been determined for agronomic traits. By evaluating 34 sugary × sugary enhancer hybrids with reciprocals in three environments, the main objectives of this work were, for agronomic and quality traits, to determine the presence or absence of reciprocal differences in the sugary × sugary enhancer hybrids, to study the interest of using sugary inbreds as seed parents of the sugary × sugary enhancer hybrids, and to determine if reciprocal differences are interacting with different genetic backgrounds and different environments. For agronomic traits as emergence, early vigor, and silking date, significant (P ≤ 0.05) reciprocal differences were found in many of the sugary × sugary enhancer hybrids, but for quality traits, significant (P ≤ 0.05) reciprocal differences were only found in a few hybrids. The sugary lines as seed parents of the crosses tended to have on average a favorable effect on agronomic traits, but this was only considerable in some environmental conditions. The difference between the sugary and sugary enhancer lines as seed parent of the crosses was strongly influenced by the genetic background.
Comparative Studies on the Physiobiochemical, Enzymatic, and Ionic Modifications in Salt-tolerant and Salt-sensitive Citrus Rootstocks under NaCl Stress
Authors: Balal Rashad M. , Khan Muhammad M. , Shahid Muhammad A. , Mattson Neil S. , Abbas Tahira , Ashfaq Muhammad , Garcia-Sanchez Franscisco , Ghazanfer Usman , Gimeno Vicente , Iqbal Zafar
Published: January 2019

A study was conducted to investigate the morphological, physiobiochemical, enzymatic, and ionic differences among four cultivated citrus (Citrus sp.) rootstocks with different salt tolerances. Two salt-tolerant rootstocks [Rangpur lime (C. limonia) and Rubidoux (C. trifoliata)] and two salt-sensitive rootstocks [Carrizo citrange (Citrus sinensis × C. trifoliata) and Sanchton citrumello (C. trifoliata × C. paradisi)], were subjected to NaCl stress in greenhouse conditions. The 9-month-old plants were exposed to four different NaCl levels (0, 30, 60, or 90 mm) in sand culture for 3 months. Plant biomass (fresh weight, dry weight, root length, shoot length, and leaf thickness), physiological attributes [number of stomata, stomatal size, number of epidermal cells, photosynthesis rate, stomatal conductance (gS), water use efficiency, and transpiration rate]. and ion content (Na+, K+, Ca+2, Mg+2, and Cl–) were adversely affected by salt stress, but salt-tolerant cultivars were comparatively less affected. Salt stress also enhanced antioxidant enzyme activity (superoxide dismutase, catalase, and peroxidase), particularly in salt-tolerant cultivars. The salt-sensitive cultivars accumulated the greatest content of Na+ and Cl– in their leaves, whereas the salt-tolerant cultivars accumulated the greatest content of Na+ and Cl– in their roots, an adaptation to combat the highly saline conditions. Overall, it was concluded that the salt tolerance of rootstocks is associated with a greater antioxidant enzyme activity and differing accumulation patterns of Na+, K+, Cl–, Mg+2, and Ca+2 in leaves and roots; these can be considered potential indicators of a cultivar's sensitivity to salt stress.
Net Carbon Exchange Rate of Fragaria Species, Synthetic Octoploids, and Derived Germplasm
Authors: Harbut Rebecca M. , Sullivan J. Alan , Proctor John T.A. , Swartz Harry J.
Published: January 2019

The net carbon exchange rate (NCER) of Fragaria species, synthetic octoploids [SO (interspecific hybrids)], F1 (SO × cultivar), and first outcross [OC1 (F1 × cultivar)] hybrids were evaluated in both field and greenhouse conditions. Plants were grown in a field trial at the Elora Research Station in Ontario, Canada, for one season and then plants were dug and moved into a greenhouse where the trial was repeated during the next season. Single leaf photosynthesis measurements and light response curves were generated at different stages of plant development. Photosynthetic capacity of the species was related to the ecological background of the species with sun-adapted species having higher rates compared with the shade-adapted species. The Fragaria species and introgressed hybrids (F1 and OC1) had significantly higher NCERs compared with the cultivars with rates 28% and 23% higher, respectively. Species and hybrids also appear to have increased adaptability to both high and low light conditions. These increases in NCER may be a heterotic effect because NCER of the hybrids were consistently higher compared with the midparent values and in some cases, they were higher than the high parent. These results suggest that the introgression of lower-ploidy Fragaria species into the cultivated strawberry (Fragaria ×ananassa) may lead to increased NCER and light adaptability.
Metabolic Responses to Heat Stress under Elevated Atmospheric CO2 Concentration in a Cool-season Grass Species
Authors: Yu Jingjin , Du Hongmei , Xu Ming , Huang Bingru
Published: January 2019

Heat is a major factor limiting growth of C3 grass species. Elevated CO2 may mitigate the adverse effects of heat stress or enhance heat tolerance. The objective of this study was to determine metabolic changes associated with improvement of heat tolerance by elevated atmospheric CO2 concentration in tall fescue (Festuca arundinacea). Plants (cv. Rembrandt) were exposed to ambient day/night temperature (25/20 °C) or heat stress (35/30 °C) and ambient CO2 concentration (400 ± 10 μmol·mol−1) or double ambient CO2 concentration (800 ± 10 μmol·mol−1) in growth chambers. Turf quality (TQ), shoot growth rate, and leaf electrolyte leakage results demonstrated that heat stress at ambient CO2 concentration inhibits turf growth and reduces cell membrane stability, whereas heat-stressed plants under elevated CO2 concentration exhibit improved TQ, shoot growth rate, and membrane stability. Plants exposed to heat stress under elevated CO2 exhibited a significantly greater amount of several organic acids (shikimic acid, malonic acid, threonic acid, glyceric acid, galactaric acid, and citric acid), amino acids (serine, valine, and 5-oxoproline), and carbohydrates (sucrose and maltose) compared with heat-stressed plants at ambient CO2. The increased production or maintenance of metabolites with important biological functions such as those involved in photosynthesis, respiration, and protein metabolism could play a role in elevated CO2 mitigation of heat stress damage. Therefore, elevated CO2 conditions may contribute to improved heat stress tolerance as exhibited by better TQ and shoot growth of heat-stressed plants. Practices to harness the power of CO2 may be incorporated into turfgrass management for plant adaptation to increasing temperatures, particularly during summer months.
Genetic Variation and Distribution of Pacific Crabapple
Authors: Routson Kanin J. , Volk Gayle M. , Richards Christopher M. , Smith Steven E. , Nabhan Gary Paul , Wyllie de Echeverria Victoria
Published: January 2019

Pacific crabapple [Malus fusca (Raf.) C.K. Schneid.] is found in mesic coastal habitats in Pacific northwestern North America. It is one of four apple species native to North America. M. fusca is culturally important to First Nations of the region who value and use the fruit of this species as food, bark and leaves for medicine, and wood for making tools and in construction. However, little is known about either distribution or genetic diversity of this species. To correct this deficiency, we used habitat suitability modeling to map M. fusca habitat types with species occurrence records. The species apparently occupies at least two distinct climate regions: a colder, drier northern region and a warmer, wetter southern region. Total area of modeled habitat encompasses ≈356,780 km2 of low-lying areas along the Pacific coast. A total of 239 M. fusca individuals sampled from across its native range were genetically compared using six microsatellite markers to assess for possible geographic structuring of genotypes. The primers amplified 50 alleles. Significant isolation by distance was identified across the ≈2600 km (straight line) where samples were distributed. These results may help establish priorities for in situ and ex situ M. fusca conservation.
Phytosterol Variability in Almond Germplasm
Authors: Fernández-Cuesta Álvaro , Kodad Ossama , Socias i Company Rafel , Velasco Leonardo
Published: January 2019

Phytosterols are important dietary components that contribute to reducing serum cholesterol levels. The objective of this research was to assess genetic diversity for total content and profile of free and esterified phytosterols in a world germplasm collection of almond [Prunus amygdalus Batsch; syn. P. dulcis (Mill.) D.A. Webb]. Steryl glycosides and acylated steryl glycosides were not measured. Fruit from 160 almond accessions were collected in 2009 and 2010. Kernel phytosterol content ranged from 1126 to 2769 mg·kg−1 in 2009 and from 1191 to 2777 mg·kg−1 in 2010. The phytosterol fraction was mainly made up of β-sitosterol (from 59.1% to 84.1% in 2009 and from 55.9% to 84.6% in 2010) and Δ5-avenasterol (from 8.9% to 25.4% in 2009 and from 8.5% to 28.2% in 2010). Significant genotypic effects were observed for kernel phytosterol content and concentration of major phytosterols. Kernel oil content was positively correlated with kernel phytosterol content in both years. The results suggested that almond germplasm contains genetic variability for both phytosterol content and profile that can be used for developing cultivars with increased levels of phytosterols and contrasting phytosterol profiles. Positive correlation between kernel phytosterol content and kernel oil content suggests the feasibility of simultaneous selection for both traits.
Characterization of Peach TFL1 and Comparison with FT/TFL1 Gene Families of the Rosaceae
Authors: Chen Yihua , Jiang Peng , Thammannagowda Shivegowda , Liang Haiying , Wilde H. Dayton
Published: January 2019

We investigated the FT/TFL1 family of peach (Prunus persica), a gene family that regulates floral induction in annual and perennial plants. The peach terminal flower 1 gene (PpTFL1) was expressed in a developmental and tissue-specific pattern that, overall, was similar to that of TFL1 orthologs in other woody Rosaceae species. Consistent with a role as a floral inhibitor, ectopic expression of PpTFL1 in arabidopsis (Arabidopsis thaliana) delayed flowering and prolonged vegetative growth. Other members of the peach FT/TFL1 family were identified from the sequenced genome, including orthologs of flowering locus T, centroradialis, brother of ft, and mother of ft and tfl. Sequence analysis found that peach FT/TFL1 family members were more similar to orthologous genes across the Rosaceae than to each other. Together these results suggest that information on genes that regulate flowering in peach could be applied to other Rosaceae species, particularly ornamentals.
Mottling on Sweet Cherry Fruit Is Caused by Exocarp Strain
Authors: Grimm Eckhard , Peschel Stefanie , Knoche Moritz
Published: January 2019

Mottling (pale spots) is clearly visible to the naked eye in all regions of the surface in all except for yellow cultivars of sweet cherry fruit (Prunus avium L.). The objective was to characterize these spots and their distribution on the exocarp. Within the spots, anthocyanins were limited to the epidermal cell layer but, in areas immediately adjacent to the spots, anthocyanins were present in the epidermal and in the hypodermal cell layers (making these areas darker). In ‘Sam’ sweet cherries, the median length and width of a spot in the cheek region were 390 and 162 μm, respectively, and the median area was 0.053 mm2 per spot. The spatial density in the cheek region averaged 1.94 (± 0.13) spots per mm2 and the percentage of surface area covered by the spots was 12.5% (± 1.07%). Epidermal cells within a spot had slightly larger projected surface areas than those in the adjacent region and thicker cell walls. The margins of the spots did not align with the anticlinal walls of the epidermal cells. The spots’ long axes were oriented parallel with the stem/stylar scar axis, whereas the slightly elongated epidermal cells within and adjacent to the spots were orientated perpendicular to the stem/stylar scar axis. The spatial density of spots and the cumulative spot area were highest in the region of the stylar scar, intermediate in the cheek and stem cavity, and lowest in the suture region. Spot spatial density on small fruit exceeded that on larger fruit, but the areas of individual spots was smaller. When an exocarp segment was excised from the cheek of a fruit, it contracted slightly as elastic strain was released. The projected surface area of the spots and that of the whole segment decreased to a similar extent. Our data suggest that spots result from a tensional failure during Stage III development in which the anthocyanin-containing hypodermal cell layer tears (schizogenously) and separates from the epidermis. This being the case, the pale spots (mottling) can be referred to as “strain spots.”
Changes in Carbohydrate Metabolism in Two Kentucky Bluegrass Cultivars during Drought Stress and Recovery
Authors: Yang Zhimin , Xu Lixin , Yu Jingjin , DaCosta Michelle , Huang Bingru
Published: January 2019

Carbohydrate metabolism is important for plant adaptation to drought stress. The objective of this study was to examine major forms of carbohydrates associated with superior drought tolerance and post-drought recovery in kentucky bluegrass (Poa pratensis) by comparing responses of different forms of carbohydrates with drought stress and re-watering in two cultivars contrasting in drought tolerance. Plants of drought-tolerant ‘Midnight’ and drought-sensitive ‘Brilliant’ were maintained well watered or subjected to drought stress for 10 days by withholding irrigation, and drought-stressed plants were re-watered for 3 days. Physiological analysis (turf quality, relative water content, and electrolyte leakage) confirmed the genetic variability of the two cultivars in drought tolerance. The two cultivars exhibited differential responses to drought stress and re-watering for the content of water-soluble sugars (sucrose, fructose, and glucose) and storage carbohydrates (starch and fructan), and ‘Midnight’ maintained higher sucrose content at 10 days of drought stress and more fructan at 3 days of re-watering. The greater accumulation of sucrose in ‘Midnight’ under drought stress corresponded with higher activities of two sucrose-synthesizing enzymes (sucrose phosphate synthase and sucrose synthase) but was not related to the sucrose-degrading enzyme activity (acid invertase). These results suggested that increased sucrose accumulation resulting from the maintenance of active sucrose synthesis could be associated with superior turf performance during drought stress, whereas increased fructan accumulation could contribute to rapid re-growth and post-drought recovery on re-watering in kentucky bluegrass.
Molecular Genetic Diversity in the Turkish National Melon Collection and Selection of a Preliminary Core Set
Authors: Frary Anne , Şığva Hasan Özgür , Tan Ayfer , Taşkın Tuncer , İnal Abdullah , Mutlu Sevgi , Haytaoğlu Mehmet , Doğanlar Sami
Published: January 2019

Turkey is a secondary center of diversity for melon (Cucumis melo) and is home to a variety of regional morphotypes. This diversity is housed in a national germplasm repository with more than 500 accessions. Molecular genetic variability of 209 melon genotypes from 115 accessions of this collection was characterized using amplified fragment length polymorphisms (AFLPs). Ten AFLP primer combinations yielded 279 reproducible fragments, which were used for dendrogram and principal coordinate analyses. These analyses showed two major clusters of Turkish melons: one group contained highly similar genotypes (maximum Dice dissimilarity coefficient of 0.18), whereas the other group was genetically more diverse (maximum dissimilarity 0.41). Although average dissimilarity was low (0.13), a broad range of genetic diversity was observed in the collection. A marker allele richness strategy was used to select a core set of 20 genotypes representing the allelic diversity of the AFLP data. The core set had double the average diversity (0.26) of the entire set and represented the major morphotypes present in the collection. Molecular genetic diversity of the core set was further validated using simple sequence repeat marker data (116 polymorphic fragments), which confirmed that the selected core set retained high levels of molecular genetic diversity.
Microsatellite Marker Development in Peony using Next Generation Sequencing
Authors: Gilmore Barbara , Bassil Nahla , Nyberg April , Knaus Brian , Smith Don , Barney Danny L. , Hummer Kim
Published: January 2019

Peonies (Paeonia), the grand garden perennial of spring and early summer, are economically important to the international cut flower market. Herbaceous peonies (Paeonia section Paeonia), tree peonies (Paeonia section Moutan), and intersectional crosses between the two types (Itoh Paeonia hybrids) are of interest to gardeners, growers, and nursery producers. Thousands of peony cultivars exist and identity is traditionally determined by experienced horticulturists knowledgeable in plant and bloom characteristics. With DNA extraction possible during any time of the year, molecular markers can provide genotype identity confirmation for dormant roots or mature post-bloom plants. The primary objective of our research was to rapidly and inexpensively develop microsatellite markers in a range of Paeonia species using barcoded Illumina libraries. A secondary objective was to apply these simple sequence repeat (SSR) markers to fingerprint 93 accessions that include tree, intersectional, and herbaceous peonies. We used 21 primers to distinguish cultivars and their close relatives. Also from our sequence information, greater than 9000 primers were designed and are made available.
Quantitative Trait Loci Associated with Sex Expression in an Inter-subspecific Watermelon Population
Authors: Prothro Jason , Abdel-Haleem Hussein , Bachlava Eleni , White Victoria , Knapp Steven , McGregor Cecilia
Published: January 2019

Sex expression is an important trait in watermelon (Citrullus lanatus), in which monoecious, andromonoecious, and trimonoecious forms are present. The andromonoecious trait is highly undesirable in watermelon breeding programs because it would require emasculation during hybrid development. In contrast to other cucurbits such as melon (Cucumis melo) and cucumber (Cucumis sativus) in which the genes involved in sex expression are well described and have been cloned, only the inheritance of the a gene associated with the andromonoecious trait has been described in watermelon. We used an intersubspecific C. lanatus var. lanatus × C. lanatus var. citroides F2 population to map quantitative trait loci (QTL) associated with percent male (%M), percent female (%F), percent hermaphrodite (%HM), and percent female of pistillate [%F/P (female + hermaphrodite)] flowers. Four chromosomal regions were identified that were associated with sex expression in watermelon. Major QTL for %F, %HM, and %F/P were colocalized on linkage group 11A and explained 31.3% to 37.7% of the phenotypic variation observed for the three traits. These QTL are suggested to be the location of the a gene in watermelon. Markers linked to two of the four QTL identified were located within 1 Mb of a 1-aminocyclopropane-1-carboxylic acid synthase (ACS) gene on the watermelon draft genome. ACS genes play a key role in sex expression in melon and cucumber and these genes are therefore candidate genes for further studies to elucidate this trait in another economically important cucurbit crop. The QTL and candidate genes identified in the present study lay the foundation for marker-assisted selection for sex expression traits in watermelon.
Photosynthetic and Transpiration Responses to Light, CO2, Temperature, and Leaf Senescence in Garlic: Analysis and Modeling
Authors: Kim Soo-Hyung , Jeong Jig Han , Nackley Lloyd L.
Published: January 2019

Characterization of leaf physiology is an important step for understanding the ecophysiology of a crop as well as for developing a process-based crop simulation model. We determined photosynthetic and transpiration responses to photosynthetic photon flux (PPF), carbon dioxide concentrations, and temperature, and parameterized a coupled leaf gas-exchange model for hardneck garlic (Allium sativum). The parameterized model performed with high accuracy and precision in predicting photosynthetic responses [r2 = 0.95, bias = 1.7 μmol·m−2·s−1, root mean square error (RMSE) = 2.4 μmol·m−2·s−1] when tested against independent data that were not used for model calibration. The model performance for transpiration rates was less satisfactory (r2 = 0.49, bias = –0.14 mmol·m−2·s−1, RMSE = 0.94 mmol·m−2·s−1). In addition, we characterized the relationships among chlorophyll meter readings, leaf photosynthetic capacity (Amax), and leaf nitrogen content in garlic leaves. The chlorophyll meter readings were a reasonable indicator of both Amax (r2 = 0.61) and leaf nitrogen (N) status (r2 = 0.51) for garlic leaves we studied. The garlic leaf gas-exchange model developed in this study can serve as a key component in ecophysiological crop models for garlic. Similarly, the quantitative relationship identified between chlorophyll meter readings and Amax in this study can provide useful information for non-destructively assessing leaf photosynthetic capacity in garlic.