bluuebunny/crossref_metadata_2025 huggingface dataset:
An Extended Linkage Map for Watermelon Based on SRAP, AFLP, SSR, ISSR, and RAPD Markers
Authors: Levi A. , Thomas C.E. , Trebitsh T. , Salman A. , King J. , Karalius J. , Newman M. , Reddy O.U.K. , Xu Y. , Zhang X.
Published: January 2019

Seventy-one amplified fragment length polymorphism (AFLP), 93 sequence related amplified polymorphism (SRAP), and 14 simple sequence repeat (SSR) markers were used to extend an initial genetic linkage map for watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. The initial map was based on 151 randomly amplified polymorphic DNA (RAPD) and 30 and inter-simple sequence repeat (ISSR) markers. A testcross population previously used for mapping of RAPD and ISSR markers was used in this study: {plant accession Griffin 14113 [C. lanatus var. citroide (L.H. Bailey) Mansf.] × the watermelon cultivar New Hampshire Midget (C. lanatus var. lanatus)} × PI 386015 [C. colocynthis (L.) Schrad.]. The linkage map contains 360 DNA markers distributed on 19 linkage groups, and covers a genetic distance of 1976 cM with an average distance of 5.8 cM between two markers. A genomic DNA clone representing 1-amino-cyclopropane-1-carboxylic acid (ACC-) synthase gene, involved in ethylene biosynthesis, was also mapped. As in previous mapping studies for watermelon, a large number of AFLP and SRAP markers were skewed away from the 1:1 segregation ratio, and had to be excluded from the final mapping analysis. The stringent mapping criteria (JoinMap 3.0 mapping program) produced linkage groups with marker order consistent with those reported in previous mapping study for watermelon.
Changes in Carbon Partitioning and Accumulation Patterns during Drought and Recovery for Colonial Bentgrass, Creeping Bentgrass, and Velvet Bentgrass
Authors: DaCosta Michelle , Huang Bingru
Published: January 2019

Efficient carbon distribution and utilization may enhance drought survival and recovery ability for perennial grasses. The objectives of this study were to examine changes in carbon partitioning and carbohydrate accumulation patterns in shoots and roots of colonial bentgrass (Agrostis capillaris L.), creeping bentgrass (A. stolonifera L.), and velvet bentgrass (A. canina L.) in response to drought and re-watering following drought, and to determine whether species variation in drought tolerance and recuperative potential is related to differences in the patterns of carbon partitioning and accumulation. The experiment consisted of three treatments: 1) well-watered control; 2) drought, irrigation completely withheld for 18 days; and 3) drought recovery, a group of drought-stressed plants were re-watered at the end of the drought treatment (18 days). Drought tolerance and recuperative ability of three species was evaluated by measuring turf quality and leaf relative water content. These parameters indicated that velvet bentgrass was most drought tolerant while colonial bentgrass had highest recuperative ability among the three species. Plants were labeled with 14CO2 to determine carbon partitioning to shoots and roots. Carbohydrate accumulation was assessed by total nonstructural carbohydrate (TNC) content. The proportion of newly photosynthesized 14C partitioned to roots increased at 12 days of drought compared to the pre-stress level, to a greater extent for velvet bentgrass (45%) than for colonial bentgrass (35%) and creeping bentgrass (30%). In general, the proportion of 14C was highest in roots, intermediate in stems, and lowest in leaves at 12 days of drought treatment for all three bentgrass species. As drought duration and severity increased (18 days), 14C partitioning increased more in leaves and stems relative to that in roots for all three species. Stem TNC content was significantly greater for drought-stressed plants of colonial bentgrass and velvet bentgrass compared to their respective well-watered control plants, whereas no differences in stem TNC content were observed between drought-stressed and well-watered creeping bentgrass. Our results suggest that increased carbon partitioning to roots during initial drought stress represented an adaptive response of bentgrass species to short-term drought stress, and increased carbon partitioning and carbohydrate accumulation in stems during prolonged period of drought stress could be beneficial for rapid recovery of turf growth and water status upon re-watering.
Chlorophyll and Carotenoid Profile and Enzymatic Activities (Chlorophyllase and Lipoxygenase) in Olive Drupes from the Fruit-setting Period to Harvest Time
Authors: Criado M. Nieves , Motilva M. José , Ramo Tomás , Romero M. Paz
Published: January 2019

The aim of this study was to monitor the pigment profile and chlorophyllase (Chlase) and lipoxygenase (Lox) activities of olive (Olea europaea L.) drupes during the development of the fruit from `Arbequina' and `Farga' in order to find better ways to characterize cultivars such as `Arbequina' that produce virgin olive oils that are highly appreciated in international markets. `Farga' was included as a comparative reference. The total pigment content in olive drupes from the two cultivars studied suffered a decrease when the maturation process began, the rate of chlorophyll degradation being more marked than that of the carotenoid pigment. Chlorophyllides a and b, cis-α-carotene, β-cryptoxanthin, and esterified xanthophylls were detected only in `Arbequina' fruit. The behavior of the Chlase and Lox activities in both cultivars was different. Chlase activity in olives from `Farga' was detected only at the end of the pit hardening period, but in the case of `Arbequina' the presence of dephytilated chlorophyllic derivatives is directly related to a higher Chlase enzymatic activity than that of `Farga' fruit. Although the level of these enzymatic activities decreased when ripening advanced in both cultivars, in `Arbequina' both enzymes showed a slight increase of activity at the latest stages of ripening.
Phenological Models of Flower Bud Stages and Fruit Growth of `Montmorency' Sour Cherry Based on Growing Degree-day Accumulation
Authors: Zavalloni Costanza , Andresen Jeffrey A. , Flore J.A.
Published: January 2019

A simulation model for determining flower bud phenological stages and fruit growth as a function of daily maximum and minimum temperatures was developed for `Montmorency' sour cherry (Prunus cerasus L.). The models were developed and tested with observations collected in the three major sour cherry production areas in Michigan located in northwestern, western central, and southwestern sections of the lower peninsula. Observations of flower bud phenology and fruit diameter were collected at 3- to 7-day intervals, in spurs and terminal shoots across multiple years. Nonlinear equations using accumulation of growing degree-days (base 4 °C) as an independent variable were fitted to observed flower bud phenological stages and fruit diameter, expressed as percentage of final fruit diameter. Simulated bud phenology stages were in agreement with observed data. Mean differences of simulated vs. observed dates of early phenological stages in the three production areas were between 4 and 1 days for side green and near 0 days for tight cluster, while during later stages (e.g., first bloom and full bloom) mean differences ranged from -2 to 0 days. Means differences of predicted fruit diameter were in the range of 0 to -3 days. Needing only daily temperature data, these simulation models have potential applicability in improving the timing and efficiency of management decisions related to crop phenology, such as pest control, fertilization, and irrigation.
Onion Trait Heritability and Response from Selection
Authors: Cramer Christopher S.
Published: January 2019

Realized heritability estimates of bolting percentage, pink root and fusarium basal rot severities and incidences, and percentage of single-centered bulbs were estimated for half-sib families of an intermediate-day, open-pollinated onion (Allium cepa L.) population using selection response analysis. Half-sib families were selected based upon an index that equally weighted bolting percentage, pink root and fusarium basal rot severities and incidences, percentage of single-centered bulbs, and bulb quality. Families were subjected to one cycle of half-sib family recurrent selection. Pink root and fusarium basal rot severity was reduced by 17% and 7%, respectively, with realized heritability estimates of 1.28 and 0.65, respectively. More progress for pink root severity was made than was selected. Disease incidence was reduced by 18% and 12%, respectively, with heritability estimates of 0.65 and 0.60, respectively. Very little progress was made for the percentage of single-centered bulbs and this was reflected in a heritability estimate of 0.17. Selection based upon multiple characters at the same time may reduce the effectiveness of making improvements in a single trait. However even with low to moderate heritability, improvements were made, and suggest that further improvements can be made through selection.
The Effect of Sweet Potato Virus Disease and its Viral Components on Gene Expression Levels in Sweetpotato
Authors: Kokkinos C.D. , Clark C.A. , McGregor C.E. , LaBonte D.R.
Published: January 2019

Sweet potato virus disease (SPVD) is the most devastating disease of sweetpotato [Ipomoea batatas (L.) Lam.] globally. It is caused by the co-infection of plants with a potyvirus, sweet potato feathery mottle virus (SPFMV), and a crinivirus, sweet potato chlorotic stunt virus (SPCSV). In this study we report the use of cDNA microarrays, containing 2765 features from sweetpotato leaf and storage root libraries, in an effort to assess the effect of this disease and its individual viral components on the gene expression profile of I. batatas cv. Beauregard. Expression analysis revealed that the number of differentially expressed genes (P < 0.05) in plants infected with SPFMV alone and SPCSV alone compared to virus-tested (VT) plants was only 3 and 14, respectively. However, these findings are in contrast with SPVD-affected plants where more than 200 genes were found to be differentially expressed. SPVD-responsive genes are involved in a variety of cellular processes including several that were identified as pathogenesis- or stress-induced.
Inflorescence Identity Gene Alleles Are Poor Predictors of Inflorescence Type in Broccoli and Cauliflower
Authors: Labate Joanne A. , Robertson Larry D. , Baldo Angela M. , Björkman Thomas
Published: January 2019

Broccoli (Brassica oleracea L. var. italica Plenck) and cauliflower (B. oleracea var. botrytis DC) are closely related botanical varieties. The underlying genetic bases of their phenotypic differences from each other are not well understood. A molecular genetic marker enabling B. oleracea germplasm curators and breeders to predict phenotype from seeds or seedlings would be a valuable tool. Mutant alleles at flower developmental pathway loci BoAP1-a, Bo-CAL-a, and glucosinolate biosynthetic pathway locus BoGSL-ELONG have been reported to be associated with a cauliflower phenotype. We surveyed mutant alleles at these three loci in a genetically diverse sample of broccoli and cauliflower accessions from the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) Plant Genetic Resources Unit (PGRU) and the University of Warwick, Genetic Resources Unit of Warwick HRI (HRI). Phenotypic and genotypic data were collected for multiple plants per accession during two field seasons. Simple genetic models assuming dominance or codominance of alleles were analyzed. Goodness-of-fit tests rejected the null model that the mutant genotype was associated with a cauliflower phenotype. A correlation analysis showed that BoAP1-a and BoCAL-a alleles or loci were significantly correlated with phenotype but the fraction of variation explained was low, 4.4% to 6.3%. Adding BoGSL-ELONG to the analysis improved predictive power using the linear regression procedure, Maximum R-square Improvement (max R2). In the best three-variable model, only 24.8% of observed phenotypic variation was explained. Because tested genetic models did not hold robustly for the surveyed accessions, it is likely that there are multiple genetic mechanisms that influence whether the phenotype is broccoli or cauliflower. Our results in commercial cultivars indicate that other genetic mechanisms are more important in determining the horticultural type than are BoAP1-a and BoCAL-a.
Volatile Ester Suppression and Recovery following 1-Methylcyclopropene Application to Apple Fruit
Authors: Ferenczi Alejandra , Song Jun , Tian Meisheng , Vlachonasios Konstantinos , Dilley David , Beaudry Randolph
Published: January 2019

The effect of 1-methylcyclopropene (1-MCP) on biosynthesis of volatiles and fruit ripening in apple (Malus ×domestica Borkh.) was investigated using `Golden Delicious', `Jonagold', and `Redchief Delicious' fruit. Application of 1-MCP to `Golden Delicious' at the preclimacteric stage effectively inhibited ripening as determined by decreased expression of genes for 1-amino-1-cyclopropane carboxylic acid (ACC) oxidase (ACO), and ACC synthase, ACO protein content, climacteric ethylene production, respiration, and volatile ester biosynthesis. Exogenous ethylene applied after 1-MCP treatment did not induce ethylene production, respiration, or volatile production. Activity for alcohol acyltransferase, which catalyzes the final step in ester formation, was demonstrable for 1-MCP-treated fruit, indicating no strict limitation on ester formation is imposed by this enzyme and that ester formation in 1-MCP-treated apple fruit is at least partially limited by reduced substrate synthesis. Once volatile ester formation had been suppressed by 1-MCP, the recovery of volatile synthesis required ≈3 weeks for `Jonagold' and 4 weeks for `Delicious' when held in air at 22 °C. For the first 2 months of storage at 0 °C in air, `Jonagold' and `Delicious' required ≈3 weeks holding at 22 °C for volatile biosynthesis to initiate; after 5 months in refrigerated storage, volatile formation was evident at the time of removal from cold storage. For `Jonagold' fruit held in controlled atmosphere (CA) storage for 2, 5, and 7 months at 0 °C, at least 3 weeks holding at 22 °C were required for volatile formation to begin to recover. The maximal amount of volatile formation was reduced 50% by 1-MCP relative to nontreated control fruit. CA storage had a similar impact on maximal volatile formation. The marketing of 1-MCP-treated fruit soon after treatment might result in the delivery of fruit to the consumer with little likelihood of recovery of volatile ester formation prior to consumption.
A Transgenic Lettuce Line with Resistance to Both Lettuce Big-vein Associated Virus and Mirafiori Lettuce Virus
Authors: Kawazu Yoichi , Fujiyama Ryoi , Sugiyama Keita , Sasaya Takahide
Published: January 2019

The coat protein (CP) gene of lettuce big-vein associated virus (LBVaV) in sense or antisense orientation in a binary vector pBI121 was transformed via Agrobacterium tumefaciens (Smith and Towns.) Conn. mediated transformation into lettuce (Lactuca sativa L.) to generate LBVaV-resistant lettuce. Nineteen T1 lines were produced; five to 10 plants of each T1 line were inoculated with LBVaV using Olpidium brassicae (Wor.) Dang.; and LBVaV was not detected in eight plants derived from six lines. T2 seedlings from the eight plants were tested for LBVaV resistance, and one line (line A-2) with the CP gene in antisense orientation was resistant to LBVaV while the other lines were susceptible. The transgenic line A-2 was also resistant to mirafiori lettuce virus (MiLV) and big-vein expressions regardless of the presence or absence of LBVaV.
Genetic Diversity Estimates for the Genus Hydrangea and Development of a Molecular Key Based on SSR
Authors: Rinehart Timothy A. , Scheffler Brian E. , Reed Sandra M.
Published: January 2019

Using 14 codominant microsatellite markers that amplify loci across 14 different Hydrangea L. species, we analyzed gene diversity and genetic similarity within Hydrangea. Samples also included Dichroa Lour., Platycrater Sieb. and Zucc., and Schizophragma Sieb. and Zucc. genera to establish their relatedness to Hydrangea species since previous work suggests they may be closely related. Our results support the close affiliation between Macrophyllae E.M. McClint. and Petalanthe (Maxim.) Rehder subsections and their separation from the other Hydrangea species. Most of the Hydrangea species analyzed cluster within their designated sections and subsections; however, genetic distance between species within each subsection varied considerably. Our data suggest that morphological analyses which labeled H. serrata (Thunb.) Ser. as a subspecies of H. macrophylla (Thunb. Ex J.A. Murr.) Ser. are probably more accurate than recent genome size data suggesting H. macrophylla ssp. macrophylla (Thunb.) Ser. and H. macrophylla ssp. serrata (Thunb.) Makino are separate species. Gene diversity estimates indicate that 64.7% of the total diversity is due to differences between species and 49.7% of the overall variation is due to differences between subsections. Low diversity suggests a lack of gene flow between species and subsections and underscores the difficulty in making wide hybrids. Since only 35.3% of the genetic variation is common to all species, unique alleles were used to develop a molecular key for unambiguous species identification and interspecific hybrid verification. Genetic similarity estimates for all 85 samples suggests a roadmap for introgressing horticulturally important traits from different Hydrangea species.
Regulatory Aspects of Ethanol Fermentation in Immature and Mature Citrus Fruit
Authors: Shi Jian Xin , Riov Joseph , Goren Raphael , Goldschmidt Eliezer E. , Porat Ron
Published: January 2019

Molecular aspects of ethanol fermentation in citrus fruit were investigated in immature and mature ‘Star Ruby’ grapefruit (Citrus paradisi Macf.) and ‘Murcott’ mandarin (Citrus reticulata Blanco). Transcript levels of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH), which play a central role in ethanol fermentation, were detectable in all stages of fruit development, but accumulation of acetaldehyde (AA) and ethanol was evident only as fruit approached maturation or after several weeks of storage. Treatment of mature fruit with ethylene enhanced ethanol fermentation in grapefruit but not in mandarin. Immature fruit of both cultivars, on the other hand, responded to ethylene by prominent, although transient, enhancement of ethanol fermentation. Exposure of mature or immature fruit to anaerobic conditions (N2 atmosphere) upregulated the expression of PDC and ADH, and increased the levels of AA and ethanol. Exposure of mature fruit to anaerobic conditions also increased the enzymatic activities of PDC and ADH. The data indicate that the potential for ethanol fermentation exists in citrus fruit throughout development, even under aerobic conditions, but AA and ethanol are detected mainly toward maturation or under prolonged storage. However, prominent, long-term molecular induction of ethanol fermentation occurs only under anaerobic conditions imposed by N2 atmosphere.
Clonal Variability among Grower Bulb Lots of Easter Lily ‘Nellie White’
Authors: Zlesak David C. , Anderson Neil O.
Published: January 2019

Potted Easter lily (Lilium longiflorum Thunb.) ranks among the top five potted flowering plants in the United States in economic value. One clone (‘Nellie White’) dominates the North American market. It is grown by less than 10 bulb producers, each maintaining their own propagation stock and practicing intraclonal strain selection. Greenhouse forcers attest to forcing differences depending on the bulb grower. The objective of this study was to determine the extent and sources of morphological variability among bulb growers. Bulb lots were obtained in 2002 (S1) and 2003 (S2) (n = 11 and n = 12 lots respectively) with 12 or 15 bulbs/lot. Grower's identification was confidential but kept consistent across shipment years. Bulbs were obtained as the 20.3 to 22.9-cm circumference commercial class, and S1 and S2 shipments were control temperature forced over two forcing cycles (FC1, FC2). Data collection included initial bulb weight and circumference; days to stem emergence (SEM), visible flower bud (VFB), and anthesis (AN); plant and inflorescence height; number of stems, leaves, flowers, and ovules per first flower/stem reaching AN; percentage of ovules forming viable seeds; leaf length and width; major lily viruses (presence/absence, relative optical density); leaf length-to-width ratios; AN-SEM, AN-VFB, and VFB-SEM. Significant differences were found among bulb lots for every trait except AN-VFB. Variability among bulb lots can be attributed to variation in initial bulb size, previous forcing cycle environment, variable lily symptomless virus (LSV) titer, and underlying genetic/epigenetic differences. Bulb circumference had the highest standardized canonical coefficient for canonical variable one in S2-FC1 and was a significant covariate in analysis of covariance; larger bulbs tended to produce larger plants. Forcing over two cycles allowed for less phenotypic variability among bulb lots in FC2 because of a common FC1 environment. All lilies were positive for LSV and negative for four other viruses tested. Significant negative correlations in S2 between relative optical density and plant height (FC1), initial bulb weight (FC2), and initial bulb circumference (FC2) indicate an effect of relative LSV titer on plant morphology. The role of LSV titer and genetic/epigenetic intergrower variability in ‘Nellie White’ warrants further investigation. Likewise, a lack of breeder/producer companies and the corollary independent grower strain selection has significant genetic consequences and complicates identification of superior ‘Nellie White’ clones.
Additive Effects of Alcohols and Polyols on Thermostability of Pepper Leaf Extracts
Authors: Anderson Jeffrey A.
Published: January 2019

Chemical chaperones (CC) are plant stress-related compounds that can stabilize protein structure in adverse environments. Modes of action are thought to involve hydrogen bonding, primarily with the solvent, and hydrophobic stabilization of the protein core. The objective of this study was to determine structure–function relationships between CC (and structurally related compounds) and thermal stability of pepper (Capsicum annuum L.) leaf proteins. Both polarity [based on log Kow (the oil–water partition coefficient)] and capacity for hydrogen bonding (based on the number of OH groups) contributed to whether low-molecular-weight alcohols and polyols stabilized or destabilized proteins at elevated temperatures. Thermal stability increased with increasing number of OH groups at a fixed number of carbon atoms per molecule. Conversely, thermal stability decreased with increasing number of carbon atoms with a fixed number of OH groups. When CC solution concentrations were adjusted to the same concentration of OH groups (1.51 × 1022 OH groups per milliliter), protein thermal stability increased with increasing CC polarity. Mixtures of different CC had additive effects on increasing protein thermostability, but mixtures of stabilizing (mannitol) and destabilizing (methanol) compounds negated each other. As a strategy for increasing plant thermotolerance, identification and removal of destabilizing compounds should be equally effective as increasing levels of stabilizers in protecting protein conformation at elevated temperatures.
Influence of Cluster Thinning on Return Bloom, Nut Quality, and Concentrations of Potassium, Nitrogen, and Non-structural Carbohydrates
Authors: Rohla Charles T. , Smith Michael W. , Maness Niels O.
Published: January 2019

Alternate bearing pecan trees [Carya illinoinensis (Wangenh.) C. Koch] were hand-thinned annually to 1, ≤2, or ≤3 fruit/cluster or not thinned when the ovule was about one-half expanded. Return bloom was monitored on (1) vegetative shoots, (2) bearing shoots without a second growth flush in the terminal position on 1-year-old branches, (3) bearing shoots without a second growth flush in the lateral position on 1-year-old branches, and (4) bearing shoots with a second growth flush that were primarily in the terminal position. Yield and nut quality were determined in addition to nonstructural carbohydrate, organically bound nitrogen (N), and potassium (K) concentrations in the roots and shoots during January. Fruit thinning improved return bloom but had little effect on weight/nut, kernel percent, or kernel grade. Fruit thinning had either a modest or no effect on nonstructural carbohydrates, organically bound N, and K concentrations. Vegetative shoots and bearing terminal shoots produced a similar number of flowers/1-year-old branch and percentage of flowering current-season shoots. Bearing lateral shoots produced fewer flowers than vegetative shoots most years and fewer flowering current-season shoots during one year. Shoots with a second growth flush produced more flowers/1-year-old branch and a larger percentage of flowering current-season shoots than did vegetative shoots 2 of 3 years. These data indicate fruit thinning of overloaded trees improved return bloom, but the lack of interactions between thinning treatment and shoot type suggests that the number of fruit/cluster was less important than total crop load in determining nut quality and return bloom. Thus removal of entire fruit clusters appears as effective as thinning fruit within a cluster to maintain adequate nut quality and promote return bloom. Nonstructural carbohydrates, organically bound N, and K were not limiting factors in bearing consistency because they were not depressed in unthinned trees. Nonstructural carbohydrates, organically bound N, and K concentrations were not closely linked to alternate bearing because return bloom was enhanced by thinning, but thinning did not affect their concentrations.
Impact of Applied Nitrogen Concentration on Growth of Elatior Begonia and New Guinea Impatiens and Susceptibility of Begonia to Botrytis cinerea
Authors: Pitchay Dharmalingam S. , Frantz Jonathan M. , Locke James C. , Krause Charles R. , Fernandez George C. J.
Published: January 2019

Plant performance and appearance in deficient and toxic levels of nutrients are well characterized. However, less is known about the potential subtleties of plant growth, form, development, nutrient uptake, and biotic stress tolerance in the broad tolerable range. Begonia [Beg (Begonia × tuberhybrida Voss)] and new guinea impatiens [NGI (Impatiens hawkeri Bull.)] were grown over a wide range of N (from 1.78 to 57.1 mm NH4:NO3 ratio at a 1:1 ratio supplied as nutrient solution) in a peat:perlite soilless substrate in greenhouse conditions. Plant growth, development, chlorophyll content, leaf angle, nutrient uptake, tissue caloric value, and susceptibility to Botrytis cinerea Pers.:Fr. disease were evaluated in two experiments. Elevated N supply resulted in decreased plant height (16% in Beg and 7% to 16% in NGI), flower count (3% to 48% in Beg and 7% to 49% in NGI), bud numbers (23% to 80% in Beg), canopy area (11% to 33% in NGI), and mass (21% to 33% in Beg and 18% to 58% in NGI). Chlorophyll content saturated at an N supply of 28.6 mm. N uptake efficiency, shoot N use efficiency, and shoot N utilization efficiency decreased with increasing N supply. Elevated levels of N supply from 7.15 to 57.1 mm also increased the susceptibility of Beg to B. cinerea disease by 10% to 80% in stems and 3% to 14% in leaves. The increase in susceptibility also corresponded with increased tissue energy content (kJ·g−1) and altered leaf orientation. This study indicates many plant changes occur between nutrient extremes that can have a significant impact on growth, development, and the ability to withstand disease.
Cytochrome c Oxidase as a Cause of Variation in Oxygen Uptake Rates Among Vegetables
Authors: Makino Yoshio , Ichimura Masayuki , Kawagoe Yoshinori , Oshita Seiichi
Published: January 2019

The effect of cytochrome c oxidase, the terminal oxidase in the respiratory chain, on O2 uptake by vegetables was investigated. Broccoli florets (Brassica oleracea L. var. italica Plenck), spinach leaves (Spinacia oleracea L.), and onion bulbs (Allium cepa L.), which were expected to show rapid, moderate, and slow O2 uptake rates, respectively, were used in the current study. The order of O2 uptake rate measured by a closed method with a gas chromatograph was broccoli florets > spinach leaves > onion bulbs. Cytochrome c oxidase activity of mitochondrial preparations from onion bulbs was lower than that of the other vegetables, as was the O2 uptake rate. The higher O2 uptake rate of broccoli florets compared to spinach leaves was caused by higher cytochrome c oxidase activity of the floral buds. Grayscale luminance was used to determine the extent and distribution of staining in the tissues due to cytochrome c oxidase activity. Active O2 uptake by floral buds of broccoli florets was caused by the high concentration of cytochrome c oxidase in the pistil and petal. The absorbance of stems of broccoli florets at 823 nm, possibly derived from absorption by copper in cytochrome c oxidase, was higher than that of onion scale leaves, which agreed with the results of cytochrome c oxidase staining. We concluded that cytochrome c oxidase contributed to the O2 uptake rate by vegetables and that cytochrome c oxidase was one of the important causes for variation in O2 uptake rates among vegetables.
Modeling the Effects of Temperature and Photosynthetic Daily Light Integral on Growth and Flowering of Salvia splendens and Tagetes patula
Authors: Moccaldi Lee Ann , Runkle Erik S.
Published: January 2019

Photosynthetic daily light integral (DLI) and temperature are two environmental factors that profoundly influence plant growth and development. Two common ornamental annual crops, salvia (Salvia splendens F. Sello ex Roem & Schult.) and marigold (Tagetes patula L.), were grown in glass greenhouses under a mean DLI of 5 to 25 mol·m−2·d−1 at temperatures from 14 to 27 °C. Growth (e.g., plant dry weight at flowering) and flowering characteristics (e.g., time to flowering and flower number) were modeled in response to the mean daily temperature and DLI by using multiple regression analysis. The rate of progress to flowering of salvia and marigold was primarily influenced by the mean air temperature. For example, time from seedling transplant to flowering of salvia decreased from 42 days to 24 days as temperature increased from 15 to 25 °C, with a mean DLI of 10 mol·m−2·d−1. Flower number and plant dry weight on the date of first flowering generally decreased with increasing temperature and decreasing DLI in both species. For example, marigold plants grown at 15 °C and a mean DLI of 25 mol·m−2·d−1 were 2.45 times greater in dry weight, had 2.12 more flowers, and had 49% larger flowers at flowering compared with plants grown at 25 °C and a mean DLI of 5 mol·m−2·d−1. The models can be used to predict the impact of changing light and temperature conditions on plant quality and flowering of these two crops.
Tufted Hairgrass Responses to Heat and Drought Stress
Authors: Watkins Eric , Huang Bingru , Meyer William A.
Published: January 2019

Tufted hairgrass [Deschampsia cespitosa (L.) Beauv.] is receiving increasing attention as a low-maintenance turfgrass for use in areas with reduced fertility or reduced sunlight. The objectives of this study were to examine physiological responses of tufted hairgrass to heat and drought stress and to distinguish whether better summer performance was related to better heat or drought tolerance. Four germplasm lines were chosen based on summer performance in field plots (two lines resistant to summer stress and two lines susceptible to summer stress) and were grown in growth chambers [14-hour photoperiod, 20/15 °C (day/night)]. Plants were exposed to either drought stress or heat stress (35/30 °C, day/night) for up to 49 days. Control plants maintained under normal conditions (20/15 °C, day/night, well watered) were included for both treatments. During the course of the study, single-leaf photosynthetic rate, photochemical efficiency, and relative water content were measured, and turf quality was visually rated. All parameters for all tufted hairgrass lines decreased under drought stress and heat stress, and the decline was more severe for summer stress-susceptible lines than for resistant lines. Lines that were previously considered resistant to summer stress exhibited superior photochemical efficiency under heat stress compared with the susceptible lines. When subjected to drought stress, the lines exhibited little or no differences in the measured parameters. These results suggest that observed variation in field summer performance among various tufted hairgrass germplasm lines may be mainly the result of their differences in heat tolerance. These results suggest that selecting for heat-tolerant germplasm could be important for further improvement in turf performance of tufted hairgrass during the summer.
Calcium Can Prevent Toxic Effects of Na+ on Tomato Leaf Photosynthesis but Does Not Restore Growth
Authors: Montesano Francesco , van Iersel Marc W.
Published: January 2019

The availability of good-quality irrigation water is decreasing worldwide, and salinity is an increasingly important agricultural problem. To determine whether detrimental effects of NaCl on plant growth and leaf physiology can be minimized by additional Ca2+ supply, tomato (Solanum lycopersicum L.) ‘Supersweet 100’ was grown hydroponically. The basic nutrient solution contained 11.1 mm NO3
− and 2.8 mm Ca2+. Three levels of NaCl (14.1, 44.4, and 70.4 mm) were added to the basic solution to determine Na+ effects on leaf physiology and growth. To determine if Ca2+ could alleviate the toxic effects of Na+, treatments with 10 or 20 mm Ca2+ combined with 44.4 or 70 mm NaCl were included as well. To distinguish between osmotic and ion-specific effects, there were three treatments in which all nutrient concentrations were increased (without NaCl) to obtain electrical conductivity (EC) levels similar to those of the NaCl treatments. Nutrient solutions with 70.4 mm NaCl reduced leaf photosynthesis, chlorophyll content, gas-phase conductance, carboxylation efficiency, and dark-adapted quantum yield. Inclusion of 20 mm Ca2+ prevented these effects of NaCl. NaCl also decreased leaf length and elongation rate. This could not be prevented by adding extra Ca2+ to the solution; reductions in leaf elongation were due to osmotic effects rather than to Na+ specifically. Likewise, plant dry weight was negatively correlated with solution EC, suggesting an osmotic effect. Leaf area development apparently was more important for dry matter accumulation than leaf photosynthesis. Adding 20 mm Ca2+ to the 70 mm NaCl solution reduced the Na+ concentration in the leaf from 79 to 24 mg·g−1.
Changes in Antioxidant Enzyme Activities and Lipid Peroxidation for Bentgrass Species in Response to Drought Stress
Authors: DaCosta Michelle , Huang Bingru
Published: January 2019

Previous investigations identified velvet bentgrass (Agrostis canina L.) as having higher drought resistance among bentgrass species. This study was designed to determine whether species variation in drought resistance for colonial bentgrass (A. capillaris L.), creeping bentgrass (A. stolonifera L.), and velvet bentgrass was associated with differences in antioxidant enzyme levels in response to drought. Plants of ‘Tiger II’ colonial bentgrass, ‘L-93’ creeping bentgrass, and ‘Greenwich’ velvet bentgrass were maintained in a growth chamber under two watering treatments: 1) well-watered control and 2) irrigation completely withheld for 28 d (drought stress). Prolonged drought stress caused oxidative damage in all three bentgrass species as exhibited by a general decline in antioxidant enzyme activities and an increase in lipid peroxidation. Compared among the three species, velvet bentgrass maintained antioxidant enzyme activities for a greater duration of drought treatment compared with both colonial bentgrass and creeping bentgrass. Higher antioxidant enzyme capacity for velvet bentgrass was associated with less lipid peroxidation and higher turf quality, leaf relative water content, and photochemical efficiency for a greater duration of stress compared with colonial bentgrass and creeping bentgrass. These results suggest that bentgrass resistance to drought stress could be associated with higher oxidative scavenging ability, especially for velvet bentgrass.
Simple Sequence Repeat Marker Analysis of Genetic Relationships within Hydrangea macrophylla
Authors: Reed Sandra M. , Rinehart Timothy A.
Published: January 2019

Genetic diversity studies using 39 simple-sequence repeat (SSR) markers were carried out with 114 taxa of Hydrangea macrophylla (Thunb.) Ser., including 87 H. macrophylla ssp. macrophylla cultivars and 20 members of H. macrophylla ssp. serrata (Thunb.) Makino. The SSR loci were highly variable among the taxa, producing a mean of 8.26 alleles per locus. Overall allelic richness was relatively high at 5.12 alleles per locus. H. macrophylla ssp. serrata contained nearly twice the allelic diversity of H. macrophylla ssp. macrophylla. The majority of genetic diversity was found to reside within the subspecies, with only 12% of the total genetic diversity observed occurring between subspecies. Although the elevation of H. macrophylla ssp. serrata to species level has recently been recommended by several hydrangea authorities, these data support the subspecies designation. Four cultivars (Preziosa, Pink Beauty, Tokyo Delight, and Blue Deckle) appeared to be hybrids between the two subspecies. Genetic similarities were found among five remontant cultivars (Bailmer, Oak Hill, David Ramsey, Decatur Blue, and Penny Mac) and several nonremontant cultivars, including General Vicomtesse de Vibraye, Nikko Blue, All Summer Beauty, and La France. No close genetic relationship was found between the remontant cultivar Early Sensation and other remontant cultivars. Genetic similarities were found among variegated and double-flower cultivars. Within H. macrophylla ssp. macrophylla, cultivars with mophead inflorescences clustered separately from most lacecap cultivars. This indicates the cultivars with lacecap inflorescences that were among some of the earliest introductions to Europe were not widely used in the breeding of mophead forms. Some presumed synonyms were found to be valid (‘Preziosa’ and ‘Pink Beauty’, ‘Rosalba’ and ‘Benigaku’, ‘Geoffrey Chadbund’ and ‘Mowe’), whereas others were not (‘Harlequin’ and ‘Monrey’, ‘Nigra’ and ‘Mandschurica’). This study identified potentially unexploited sources of germplasm within H. macrophylla and relationships between existing cultivars of this popular shrub. This information should be of value when selecting parents for breeding programs.
A New Gene, bic, with Pleiotropic Effects (with T P V) for Bicolor Flowers and Dark Olive Brown Seed Coat in Common Bean
Authors: Bassett Mark J. , Miklas Phillip N.
Published: January 2019

‘Painted Lady’ (Phaseolus coccineus L.) has bicolor flowers with vermilion banner petal and white wing petals. This flower color pattern is not known in common bean (P. vulgaris L.). The bicolor trait was backcrossed into common bean and its inheritance investigated, including allelism tests with other genes in common bean (T, P, and V) for flower color or pattern and brown seed coat. A pure line (line 33) with bicolor flower and dark olive brown seed coat was crossed to line 5-593 (no flower pattern and black seed coat). Data from the F2 and F3 progenies from that cross demonstrated that a single recessive gene controlled both the bicolor flower and dark olive brown seed coat by pleiotropic gene action. Allelism tests between the bicolor trait (line 179c) and standard genetic tester stocks involving the T, P, V, and Wb (white banner) genes for flower color or seed coat color demonstrated independence of bicolor from those genes and further supported the hypothesis of pleiotropic action on flower and seed coat. Also, the Wb gene was demonstrated to be independent of T and P. The gene symbol bic is proposed for the bicolor gene.
Characterization of a New Natural Periclinal Navel–Satsuma Chimera of Citrus: ‘Zaohong’ Navel Orange
Authors: Zhang Min , Deng Xiuxin , Qin Changping , Chen Chunli , Zhang Hongyan , Liu Qing , Hu Zhiyong , Guo Linlin , Song Wenhua , Tan Yong , Liao Shengcai
Published: January 2019

‘Zaohong’ navel orange [Citrus sinensis (L.) Osbeck + C. unshiu Marc.], a new strain of citrus from a graft chimera, was discovered in China. It was diploid and arose at the junction where a ‘Robertson’ navel orange scion was top-worked onto a Satsuma mandarin (C. unshiu). Some characteristics determined by the L1 cell layer, such as juice sacs of fruit and stoma length, were similar to those of Satsuma mandarin, while others, including leaf index, fruit shape, navel, and color and aroma of the rind, were determined by the L2 cell layer, were similar to ‘Robertson’ navel orange. High-performance liquid chromatography analysis of the carotenoid extracts of the flesh of ‘Zaohong’ navel orange indicated that it had the carotenoids profile of Satsuma mandarin with β-cryptoxanthin as the predominant component in the juice sacs in mature fruit. Simple sequence repeats (SSR) and chloroplast simple sequence repeats (cpSSR) analysis showed that both nuclear and chloroplast genomes of ‘Zaohong’ navel orange were composed of both donor plants. On the basis of these facts, ‘Zaohong’ navel orange was found to be a periclinal chimera consisting of L1 derived from Satsuma mandarin and L2/L3 from ‘Robertson’ navel orange. It combined the valuable traits of both donor plants, matured ≈1 month earlier than the present navel orange cultivars, and therefore had good potential in citrus fresh market.
Engineering Resistance to Multiple Prunus Fruit Viruses Through Expression of Chimeric Hairpins
Authors: Liu Zongrang , Scorza Ralph , Hily Jean-Michel , Scott Simon W. , James Delano
Published: January 2019

Prunus L. fruit production is seriously affected by several predominant viruses. The development of new cultivars resistant to these viruses is challenging but highly desired by breeders and growers. We report a posttranscriptional gene silencing-based approach for engineering multivirus resistance in plants. A single chimeric transgene, PTRAP6, was created by the fusion of 400 to 500-base pair (bp) gene fragments from six major Prunus fruit viruses, including american plum line pattern virus, peach mosaic virus, plum pox virus (PPV), prune dwarf virus (PDV), prunus necrotic ringspot virus, and tomato ringspot virus (ToRSV). Both strands of PTRAP6 were found being transcribed as an ≈2.5-kilobp transcript in planta without splicing interruption. To induce gene silencing/virus resistance, we placed two copies of PTRAP6 in an inverted repeat under the control of the cauliflower mosaic virus 35S promoter and separated by an intron spacer fragment to create PTRAP6i. Inoculation of the resulting transgenic Nicotiana benthamiana Domin. plants revealed that 12 of 28 R0 PTRAP6i transgenic lines (43%) were resistant to ToRSV ranging from mild symptoms to symptom-free phenotypes. Detailed analysis of two of three highly resistant homozygous R3 generation lines demonstrated that they were resistant to all three viruses tested, including PDV, PPV, and ToRSV. The remaining three viruses targeted by PTRAP6i were either unavailable for this study or were unable to systemically infect N. benthamiana. Transgene-wide and -specific small interfering RNA species were detected along with disappearance of transgene transcript in the resistant lines, indicating that posttranscriptional gene silencing underlies the mechanism of resistance. This work presents evidence that PTRAP6i is able to confer gene silencing-based resistance to multiple Prunus fruit viruses.
Developing a Sweet Corn Simulation Model to Predict Fresh Market Yield and Quality of Ears
Authors: Lizaso J.I. , Boote K.J. , Cherr C.M. , Scholberg J.M.S. , Casanova J.J. , Judge J. , Jones J.W. , Hoogenboom G.
Published: January 2019

Current production of sweet corn (Zea mays L.) in the United States is 4.0 million Mg with a value of $807 million. The fresh market component amounts to three-fourths of this value with California, Florida, and Georgia harvesting half of the U.S. fresh market production. Existing maize simulation models have limited potential to assist sweet corn production as a result of the distinctive nature of the marketed end product (i.e., fresh market ears versus dry mature kernels). The purpose of this study was to develop a sweet corn simulation model. The Cropping System Model-Crop-Environment Resource Synthesis CSM-CERES-Maize simulation model, version 4.0, was modified to improve the simulation of ear growth, to predict ear fresh market yield, and to predict fresh market ear quality according to U.S. standards. A field experiment conducted in Florida in 2003 was used for model development. Five nitrogen fertilization levels (0, 67, 133, 200, and 267 kg·ha−1 N) were applied to a sh2-based commercial hybrid with a Bt gene sown at 8.2 plants/m2. Three additional experiments conducted in 2002, 2004, and 2005 provided independent data to evaluate the new model. In 2002, the treatments and hybrid were the same as mentioned, but the population density was 5.5 plants/m2. A yellow sh2-based hybrid with a Bt gene was planted at 6.1 plants/m2 in 2004. In 2005, a bicolor sh2-based hybrid with a Bt gene was planted at 8.1 plants/m2. The 2004 and 2005 experiments had 100% and 150% of the Florida N recommendations applied to the crop. Results indicated that the new model was able to simulate adequately crop and ear growth of sweet corn. The ear dry weight simulation was improved as indicated by 30% reduction of root mean square of the error (RMSE) when the new model was compared with the original CSM-CERES-Maize. Total ear fresh weight yield and marketable yield were also simulated reasonably well with RMSE values of 3367 and 3502 kg·ha−1, respectively. The simulation of ear quality was consistently overpredicted at intermediate levels of N fertilization, indicating the need to further examine the impact of limited N on ear quality.
Leaf Senescence and Protein Metabolism in Creeping Bentgrass Exposed to Heat Stress and Treated with Cytokinins
Authors: Veerasamy Mahalaxmi , He Yali , Huang Bingru
Published: January 2019

Heat stress induces leaf senescence and causes changes in protein metabolism. The objective of this study was to investigate effects of exogenous application of a synthetic form of cytokinin, zeatin riboside (ZR), on protein metabolism associated with leaf senescence under heat stress for a cool-season grass species. Creeping bentgrass (Agrostis stolonifera L.) (cv. Penncross) plants were exposed to optimum temperature control (20/15 °C, day/night) and heat stress (35/30 °C) in growth chambers. Before heat stress treatments, foliage was sprayed with 10 μmol ZR or water (untreated) for 3 days and then once per week during 35 days of heat stress. Leaf chlorophyll content, photochemical efficiency (Fv/Fm), and soluble protein content declined, whereas protease activity increased during heat stress. Treatments with ZR helped maintain higher leaf chlorophyll content, Fv/Fm, and soluble protein content under heat stress. Protease activity in ZR-treated plants was lower than that of untreated plants. Zeatin riboside-treated plants had less severe degradation of ribulose-1,5-bisphosphate carboxylase proteins than untreated plants exposed to heat stress. In addition, ZR treatment upregulated the expression of 32- and 57-kDa proteins under heat stress conditions. These results demonstrated that the exogenous application of ZR ameliorated the negative effects of heat stress, as manifested by suppression or delay of leaf senescence. Cytokinins may have helped to alleviate heat stress injury, probably by slowing down the action of protease and by induction or upregulation of heat-shock proteins.