bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheological Basis of Splitting in Carrot Storage Roots
Authors: Sorensen Lis , Harker Frederick Roger
Published: January 2019

Tissue properties may strongly influence the occurrence of harvest splitting in carrot (Daucus carota L.) storage roots, a disorder generally assumed to be triggered by a high water status in the storage root. Strain within the root, as well as extensibility of root tissue by using a materials testing instrument was measured. Strain was estimated after incubation of transverse root slices in water. Measurements of the gap that developed as a result of a radial cut into the center of the slice were then used to estimate strain within the root. Extensibility of strips of carrot tissue was measured through two cycles of extension and relaxation, which allowed both elastic and plastic extensibility to be determined. Strain assessment demonstrated that carrot cells have considerable potential to increase in volume when placed in water. In some roots, phloem parenchyma adjacent to the cambium expanded to a greater extent than tissues at the periphery of the root, indicating that rigidity of cells varied across the carrot radius. Tissue extensibility was predominantly elastic, indicating the cells are unlikely to dissipate some of the strain that occurs during periods of rapid water uptake through plastic deformation. However, these measurements of extensibility were related to the properties of cells along the entire 20-mm length of the tissue strip that was used. Because we demonstrated that mechanical properties can vary within a small distance, it is concluded that future studies into the mechanical properties of carrot storage root tissue will rely on empirical strain measurements.
PPi Formation by Reversal of the Tonoplast-bound H+-pyrophosphatase from `Valencia' Orange Juice Cells
Authors: Marsh Kenneth , Gonzalez Pedro , Echeverría Ed
Published: January 2019

Tonoplast vesicles isolated from juice cells of mature `Valencia' oranges [Citrus sinensis (L.) Osbeck] showed similar tonoplast-bound vacuolar ATPase (V-ATPase) and inorganic pyrophosphatase (V-PPiase) activity as measured by product formation. Both proton pumps were able to generate a similar pH gradient, although steady-state was reached faster with ATP as substrate. When a ΔpH of 3 units was imposed (vesicle lumen pH of 4.5 and incubation medium of 7.5), tonoplast-bound PPiase was not able to significantly amplify the existing ΔpH. Although not able to function as a H+ pump, V-PPiase effectively synthesized PPi in the presence of inorganic phosphate (Pi). Formation of PPi by V-PPiase was enhanced by ATP but inhibited by NaF, gramicidin, and by antibodies raised against V-PPiase from mung bean [Vigna radiata (L.) R. Wilcz. (Syn. Phaseolus aureus Roxb.)]. Immunological analysis demonstrated an increase in V-PPiase protein with fruit maturity. Data indicate that under in vivo conditions, the V-PPiase of mature orange juice cells acts as a source of inorganic pyrophosphate (PPi) but not as a H+ pump. We propose that synthesis of PPi provides a mechanism for recovery of stored energy in the form of the pH gradient across the vacuole during later stages of development and postharvest storage.
Capsaicinoid Inheritance in an Interspecific Hybridization of Capsicum annuum × C. chinense
Authors: Zewdie Yayeh , Bosland Paul W.
Published: January 2019

Pungency, caused by the presence of capsaicinoids, is a major quality-determining factor in chile (CapsicumL. sp.) The inheritance of nordihydrocapsaicin, capsaicin, dihydrocapsaicin, isomer of dihydrocapsaicin, and homodihydrocapsaicin has not yet been determined. Generations mean analysis revealed that additive, dominance, and interaction effects were significant for capsaicin, dihydrocapsaicin, and isomer of dihydrocapsaicin in an interspecific hybridization of C. annuum L. × C. chinense Jacq. A simple additive-dominance model was sufficient to explain the genetic variation for nordihydrocapsaicin and homodihydrocapsaicin. Except dihydrocapsaicin and isomer of dihydrocapsaicin in the BCP1 family, the values of backcross families shift toward the recurrent parents. Because of the significant additive gene effect and the tendency of the values of the capsaicinoids at backcross families to shift toward the recurrent parents, repeated backcrossing and selection will increase and decrease (depending on the recurrent parent) the capsaicinoid content. Positive genetic correlations were observed between the capsaicinoids and the values ranged from 0.4 to 0.8. The estimated number of effective factors were 0.4 for nordihydrocapsaicin, 0.6 for homodihydrocapsaicin, 0.9 for isomer of dihydrocapsaicin, 1.1 for dihydrocapsaicin, 2.8 for total capsaicinoids, and 6.2 for capsaicin. Different gene actions and a different number of effective factors involved in the capsaicinoids inheritance imply that different genes are controlling the synthesis of each capsaicinoid.
Shortwave Ultraviolet Irradiation for Control of Decay Caused by Botrytis cinerea in Bell Pepper: Induced Resistance and Germicidal Effects
Authors: Mercier Julien , Baka Mebarek , Reddy Baskhara , Corcuff Ronan , Arul Joseph
Published: January 2019

Shortwave ultraviolet radiation (UV-C) was tested for controlling natural infections and inducing resistance to fungal decay caused by Botrytis cinerea Pers.: Fr. (gray mold rot) in bell pepper [Capsicum annuum L. var. annuum (Grossum Group)] fruit. All UV-C doses tested (0.22, 0.44, 0.88, or 2.20 kJ·m-2) caused a reduction in the number of natural infections occurring during storage at 13 °C. A UV-C dose of 0.88 kJ·m-2 controlled most effectively natural infections in peppers stored at both 13 or 20 °C. Although UV-C was found to be highly germicidal to B. cinerea conidia exposed on agar or on fruit wounds, it did not prevent infection of fruit inoculated with the pathogen 24 hours before exposure to UV-C. However, fruit which were exposed to UV-C 24 hours before inoculation with B. cinerea had a lower percentage of infections. For this reason, UV-C appears to act mainly as an inducer of disease resistance in this crop rather than a sanitizing agent. UV-C was effective in inducing resistance to B. cinerea in fruit at various stages of maturity, from green to red. Disease resistance was also induced in fruit which had been stored for 7 days before UV-C treatment. The effect of UV-C doses was found to be additive as two successive exposures at 0.44 kJ·m-2 had an equivalent effect as one exposure to the optimal dose of 0.88 kJ·m-2. However, two successive exposures to 0.88 kJ·m-2 were less effective than one exposure to this dose.
Muskmelon Fruit Soluble Acid Invertase and Sucrose Phosphate Synthase Activity and Polypeptide Profiles during Growth and Maturation
Authors: Lester Gene E. , Arias Luis Saucedo , Gomez-Lim Miguel
Published: January 2019

Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is the single most important consumer preference attribute. During fruit ripening, sucrose accumulates when soluble acid invertase (AI) activity is less then sucrose phosphate synthase (SPS) activity. To genetically heighten fruit sugar content, knowledge of sugar accumulation during fruit development in conjunction with AI and SPS enzyme activities and their peptide immunodetection profiles, is needed. Two netted muskmelon cultivars, Valley Gold a high sugar accumulator, and North Star a low sugar accumulator, with identical maturity indices were assayed for fruit sugars, AI and SPS activity, and immunodetection of AI and SPS polypeptides 2, 5, 10, 15, 20, 25, 30, 35, or 40 (abscission) days after anthesis (DAA). Both cultivars, grown in the Fall, 1998 and Spring, 1999, showed similar total sugar accumulation profiles. Total sugars increased 1.5 fold, from 2 through 5 DAA, then remained unchanged until 30 DAA. From 30 DAA until abscission, total sugar content increased, with `Valley Gold' accumulating significantly more than `North Star'. During both seasons, sucrose was detected at 2 DAA, which coincided with SPS activity higher than AI activity, at 5 through 25 DAA, no sucrose was detected which coincided with SPS activity less than AI activity. At 30 DAA when SPS activity was greater than AI activity, increased sucrose accumulation occurred. `Valley Gold' at abscission had higher total sugar content and SPS activity, and lower AI activity than `North Star'. `North Star' had AI isoforms at 75, 52, 38, and 25 kDa (ku) that generally decreased with maturation, although the isoform at 52 ku remained detectable up to anthesis (40 DAA). `Valley Gold' had the same four AI isoforms, all decreased with maturation and became undetectable by 20 DAA. Both `Valley Gold' and `North Star' had one SPS band at 58 ku that increased with DAA, and coincided with SPS activity. `Valley Gold' had a more intense SPS polypeptide band at abscission than `North Star'. Thus, netted muskmelon fruit sugar accumulation may be increased, either by genetic manipulation or by selecting for cultivars with a specific number of down-regulated AI isoforms, and higher SPS activity during fruit ripening.
Marker-assisted Selection for Powdery Mildew Resistance in Grapes
Authors: Dalbó M.A. , Ye G.N. , Weeden N.F. , Wilcox W.F. , Reisch B.I.
Published: January 2019

The efficiency of marker-assisted selection for powdery mildew (Uncinula necator (Schw.) Burr) resistance in grapes (Vitis L. sp.) was studied using molecular markers associated with a major QTL (quantitative trait loci) for this trait. Initially, genetic maps were constructed from a segregating population of the cross `Horizon' × Illinois 547-1 (a hybrid between V. rupestris Scheele and V. cinerea Engelm.). A major QTL from Ill. 547-1, the resistant parent, explained 41% of the variation. One RAPD (randomly amplified polymorphic DNA) marker and one AFLP (amplified fragment length polymorphism) marker, obtained by bulked segregant analysis, showed the highest association with powdery mildew resistance in the mapping population. Segregation of the QTL was followed in different crosses by CAPS (cleaved amplified polymorphic sequence) markers developed from these two markers. An allele-specific amplified polymorphism that segregates as present/absent was also developed from the CS25b locus. Powdery mildew resistance was evaluated visually on a 1 to 5 scale in four different seedling populations. Two populations originated from crosses using Ill. 547-1 as the resistant parent. Two other populations were from crosses with NY88.0514.03, a resistant seedling from the original `Horizon' × Ill. 547-1 mapping population. Segregation ratio distortions were observed in some crosses. In these cases, the allele associated with the QTL for powdery mildew resistance was less frequent than the alternate allele. In all crosses, the markers were closely associated with resistance. If selection were based on markers, the percentage of susceptible individuals (classes 4 and 5) would decrease from 24% to 52% to 2% to 18%. Selection efficiency was greatest in crosses where segregation distortion was most intense.
Synchrony of Inflorescence Initiation and Shoot Growth in Selected Protea Cultivars
Authors: Gerber Audrey I. , Theron Karen I. , Jacobs Gerard
Published: January 2019

Protea L. sp. can be assigned to groups according to similar times of flower initiation and harvest. The stages occurring during flower initiation and their synchrony relative to shoot growth were investigated for three cultivars when flower initiation occurred on the spring growth flush. For all three cultivars, the spring flush was preformed and enclosed in the apical bud before spring budbreak. During elongation of the spring flush, the apical meristem produced floral primordia which differentiated into involucral bracts. After completion of the spring flush, meristematic activity continued and produced floral bracts with florets in their axils. The different cultivars were characterized by differences or similarities in the time of budbreak, and the rates of shoot growth, appendage formation, and flower development. Insight into the time of flower initiation relative to vegetative growth could be useful in making management decisions, as well as forming a basis for manipulation of the flowering process.
Genetic Diversity and Relationships in Malus sp. Germplasm Collections as Determined by Randomly Amplified Polymorphic DNA
Authors: Oraguzie Nnadozie C. , Gardiner Sue E. , Basset Heather C.M. , Stefanati Mirko , Ball Rod D. , Bus Vincent G.M. , White Allan G.
Published: January 2019

Four subsets of apple (Malus Mill.) germplasm representing modern and old cultivars from the repository and apple genetics population of the Horticulture and Food Research Institute of New Zealand Limited were used in this study. A total of 155 genotypes randomly chosen from the four subsets were analyzed for random amplified polymorphic DNA (RAPD) variation. Nine decamer primers generated a total of 43 fragments, 42 of which were polymorphic across the 155 genotypes. Pairwise distances were calculated between germplasm subsets using the distance metric algorithm in S-PLUS, and used to examine intra-and inter-subset variance components by analysis of molecular variation (AMOVAR). A phenogram based on unweighted pair group method with arithmetic average (UPGMA) cluster analysis was constructed from the pairwise distances and a scatter plot was generated from principal coordinate analysis. The AMOVAR showed that most of the variation in the germplasm (94.6%) was found within subsets, suggesting that there is significant variation among the germplasm. The grouping of genotypes based on the phenogram and scatter plot generally did not reflect the pedigree or provenance of the genotypes. It is possible that more RAPD markers are needed for determining genetic relationships in apple germplasm. Nevertheless, the variation observed in the study suggests that the current practice of sublining populations in the first generation to control inbreeding may not be necessary in subsequent generations. If these results are confirmed by fully informative molecular markers, germplasm managers should reassess the structure of their genetics populations. There may be a need to combine sublines in order to capture the maximum genetic diversity available and to streamline breeding efforts.
Linkage Mapping in a Watermelon Population Segregating for Fusarium Wilt Resistance
Authors: Hawkins Leigh K. , Dane Fenny , Kubisiak Thomas L. , Rhodes Billy B. , Jarret Robert L.
Published: January 2019

Isozyme, randomly amplified polymorphic DNA (RAPD), and simple sequence repeats (SSR) markers were used to generate a linkage map in an F2 and F3 watermelon [Citrullus lanatus (Thumb.) Matsum. & Nakai] population derived from a cross between the fusarium wilt (Fusarium oxysporum f. sp. niveum) susceptible `New Hampshire Midget' and resistant PI 296341-FR. A 112.9 cM RAPD-based map consisting of 26 markers spanning two linkage groups was generated with F2 data. With F3 data, a 139 cM RAPD-based map consisting of 13 markers covering five linkage groups was constructed. Isozyme and SSR markers were unlinked. About 40% to 48% of the RAPD markers were significantly skewed from expected Mendelian segregation ratios in both generations. Bulked segregant analysis and single-factor analysis of variance were employed to identify RAPD markers linked to fusarium wilt caused by races 1 and 2 of F. oxysporum f. sp. niveum. Current linkage estimates between the resistance trait and the marker loci were too large for effective use in a marker-assisted selection program.
Alternaria Late Blight (Alternaria alternata) Resistance in Pistachio (Pistacia vera) and Selection of Resistant Genotypes
Authors: Chao Chih-Cheng T. , Parfitt Dan E. , Michailides Themis J.
Published: January 2019

Pistachio (Pistacia vera L.) progeny were evaluated at two locations in California for resistance to alternaria late blight caused by Alternaria alternata (Fries) Keissler in 1995 and 1997. Large differences in alternaria late blight infection among seedlings were observed. Narrow sense heritabilities based on half-sib analysis of 20 open pollinated families were 0.48 and 0.11 at Kearney Agricultural Center in 1995 and 1997, respectively, and 0.56 and 0.54 at the Wolfskill Experimental Orchard near Davis in 1995 and 1997, respectively. Differences among families to alternaria late blight infection were highly significant and associated with the female parents. Fifty-eight highly resistant seedlings were identified for future cultivar selection efforts.
Foliar-Applied Surfactants and Urea Temporarily Reduce Carbon Assimilation of Grapefruit Leaves
Authors: Orbovic Vladimir , Jifon John L. , Syvertsen James P.
Published: January 2019

Although urea can be an effective adjuvant to foliar sprays, we examined effects of additional surfactants on urea penetration through leaf cuticles along with the effect of urea with and without surfactants on net gas exchange of leaves of `Marsh' grapefruit (Citrus paradisi Macf.) trees budded to Carrizo citrange (C. sinensis L. Osbeck × Poncirus trifoliata L. Raf.) rootstock. Various combinations of urea, a nonionic surfactant (X-77), and an organosilicone surfactant (L-77), were applied to grapefruit leaves and also to isolated adaxial cuticles. When compared to X-77, L-77 exhibited superior surfactant features with smaller contact angles of droplets deposited on a teflon slide. Both L-77 and X-77 initially increased penetration rate of urea through cuticles, but the effect of X-77 was sustained for a longer period of time. The total amount of urea which penetrated within a 4-day period, however, was similar after addition of either surfactant. Solutions of either urea, urea + L-77, urea + X-77, or L-77 alone decreased net assimilation of CO2 (ACO2) for 4 to 24 hours after spraying onto grapefruit leaves. A solution of X-77 alone had no effect on ACO2 over the 4-day period. Although reductions in ACO2 were similar following sprays of urea formulated with two different surfactants, the underlying mechanisms may not have been the same. For the urea + X-77 treatment, X-77 increased the inhibitory effects of urea on ACO2 indirectly by increasing penetration of urea into leaves. For the urea + L-77 formulation, effects of L-77 on ACO2 were 2-fold, direct by inhibiting ACO2 and indirect by increasing urea penetration. One hour after application, scanning electron microscopy (SEM) of leaf surfaces treated with X-77 revealed that they were heavily coated with the residue of the surfactant, whereas leaves treated with L-77 looked similar to nontreated leaves with no apparent residues on their surfaces. The amount of X-77 residue on the leaves was lower 24 hours after application than after 1 hour as observed by SEM.
Inheritance of Flowering, Maturity, Fruit Yield, and Winter Hardiness of Sea Buckthorn (Hippophae rhamnoides)
Authors: Tang Xurong , Tigerstedt Peter M.A.
Published: January 2019

Eight characters relating to flowering and maturity, berry yield, and winter hardiness were estimated on the basis of intersubspecific or interprovenance hybrids to determine heterosis, heritability, and genetic and phenotypic correlations in sea buckthorn (Hippophae rhamnoides L.). Two provenances of ssp. rhamnoides, one of Finnish (Fin) and one of Danish (Dan) origin, were dominant to ssp. sinensis and Russian derived provenances (ssp. turkestanica) for most characters related to flowering or maturity. This tendency for dominance or overdominance also extended to berry yield and winter hardiness, except for hybrids between Finnish origins and Siberian (ssp. mongolica) origins. The start of maturity (Ms) and half maturity (Mh) showed the highest heritabilities (h2 = 0.88 and 0.81, respectively). The hybrids were matroclinal, suggesting that Ms and Mh may be sex-linked or cytoplasmically inherited characters. Winter hardiness was the trait with the lowest heritability (h2 = 0.02), suggesting that the climate at the testing site was not severe enough to differentiate variation among half sibs or full sibs derived from Fin x Dan, which on average proved hardier than the native parental provenance Fin. Full maturity (Mf) showed a moderate heritability but was stable across 2 years (rB = 1). High genetic correlations among Mf, Ms, and Mh (rG = 0.94, 0.96, and 1.00, respectively) suggest that these characters were controlled by the same genes. Yield showed a negative genetic correlation with all characters pertaining to flowering and maturity, indicating that selection for early flowering or early maturity should result in a gain in yield.
Classical and Molecular Genetic Studies of the Strong Greenish Yellow Seedcoat Color in `Wagenaar' and `Enola' Common Bean
Authors: Bassett Mark J. , Lee Rian , Otto Carla , McClean Phillip E.
Published: January 2019

Inheritance of the strong greenish-yellow (SGY) seedcoat color in `Wagenaar' common bean (Phaseolus vulgaris L.) was investigated. Line 5-593 is a determinate, Florida dry bean breeding line (with small black seeds) used as the recurrent parent in the development of many genetic stocks, e.g., g b v BC3 5-593. Through crosses with genetic tester stocks, the seedcoat genotype of `Wagenaar' was confirmed to be C J g b vlae Rk. Three randomly amplified polymorphic DNA markers (OAP7850, OAP31400, and OU14950) that cosegregated with the G seedcoat color locus were developed from the F2 population derived from the cross g b v BC2 5-593 × G b v BC3 5-593. From the cross `Wagenaar' × g b v BC3 5-593, 80 F2 plants were classified into 54 non-SGY and 16 SGY seedcoat color plants. When the OAP7850 marker was applied to that population, linkage was not observed with the non-SGY and SGY phenotypes. Conversely, a molecular marker (OAP12400, that was developed from the F2 from the cross `Wagenaar' × g b v BC3 5-593) linked to the locus controlling the SGY phenotype segregated independently of the G locus. Therefore, SGY phenotype is not controlled by the G locus. An F3 progeny test of 76 F2 plants from the cross `Wagenaar' × g b v BC3 5-593 confirmed the hypothesis that a single recessive gene (for which we propose the symbol gy) controls the seedcoat color change from pale greenish yellow (PGY) to SGY. Through crosses with genetic tester stocks, the seedcoat genotype of `Enola' was determined to be C J g b vlae Rk. The test cross `Enola' × `Wagenaar' demonstrated that `Enola' also carries the gy gene. The relationship of `Enola' to the `Mayocoba' market class of common bean and to `Azufrado Peruano 87' is discussed.
Variability in Antioxidant Activity in Blueberry and Correlations among Different Antioxidant Activity Assays
Authors: Connor Ann Marie , Luby James J. , Tong Cindy B.S.
Published: January 2019

Variation in antioxidant activity (AA), total phenolic content (TPH), and total anthocyanin content (ACY) was examined in 1998 and 1999 in fruit of 52 (49 blue-fruited and 3 pink-fruited) genotypes from a blueberry breeding population. The species ancestry included Vaccinium corymbosum L. (northern highbush blueberry), V. angustifolium Ait. (lowbush blueberry), V. constablaei Gray (mountain highbush blueberry), V. ashei Reade (rabbiteye blueberry), and V. myrtilloides Michx. (lowbush blueberry). Using a methyl linoleate oxidation assay (MeLO) on acidified methanolic extracts of the berries, a 5-fold variation was found in AA in 1998 and a 3-fold variation in 1999 among the blue-fruited genotypes. Analyses of variance (ANOVA) revealed variation among genotypes (P < 0.0001) in single and combined years, regardless of inclusion of pink-fruited selections and adjustment for berry size. While mean AA of all genotypes did not change between the 2 years, ranking of some genotypes for AA changed significantly between 1998 and 1999. Of the 10 genotypes that demonstrated the highest AA in 1998, four were among the 10 genotypes that demonstrated highest AA in 1999. Similarly, of the 15 genotypes with the highest AA, 10 were the same both years. As with AA, mean TPH of all genotypes did not change between years and ANOVA demonstrated genotypic variation regardless of adjustment for berry size/weight or exclusion of pink-fruited selections. Changes in genotype rank occurred between years. The difference in TPH between lowest- and highest-ranking blue-fruited genotypes was ≈2.6-fold in both 1998 and 1999. Seven of the 10 highest-ranking genotypes were the same both years and TPH correlated with AA (r = 0.92, P < 0.01) on a genotype mean basis for combined years. ACY correlated less well with AA (r = 0.73, P < 0.01 for combined years). When genotypes were categorized into six groups according to species ancestry, V. myrtilloides and V. constablaei × V. ashei crosses ranked highest and second highest, respectively, for AA in both years. The groups comprised of V. corymbosum genotypes, V. angustifolium genotypes, and those with both V. corymbosum and V. angustifolium in their lineage were indistinguishable from each other. Samples from some of the genotypes were analyzed for oxygen radical absorbance capacity and ferric-reducing antioxidant power, and these aqueous-based antioxidant assays correlated well with the lipid emulsion-based MeLO (all r ≥ 0.90, P < 0.01). The three antioxidant assays may be equally useful for screening in a blueberry breeding program and the choice of assay may depend on the goal of the program and the resources available.
Microsatellite-based Paternity Analysis in Polyploid Sweetpotato
Authors: Buteler M.I. , LaBonte D.R. , Jarret R.L. , Macchiavelli R.E.
Published: January 2019

Using codominant molecular markers (microsatellites) for paternity identification was investigated in hexaploid sweetpotato [Ipomoea batatas (L.) Lam.]. Two experimental populations (CIP and LAES), each consisting of progeny of known parentage, were scored for the presence or absence of alleles segregating at IB-316 and IB-318 microsatellite loci. Paternity was assessed using paternity exclusion and the most-likely parent methods. In the former, paternity is assigned based on the identification of incompatible parent-progeny marker data. In contrast, the latter method incorporates paternity exclusion and a log-likelihood or LOD score that weighs progeny allelic patterns as to the likelihood that they could have come from a given paternal parent. The number of correctly allocated progeny differed for the methods. Paternity exclusion correctly allocated 7% and 25% of the progeny in the LAES and CIP populations, respectively. The most-likely parent method correctly allocated 23% and 88% of the progeny in the LAES and CIP populations, respectively. The greater misassignments in the LAES population were attributed to low allelic diversity at the LAES IB-318 locus and a larger parental population. This study demonstrates the feasibility of identifying paternity in sweetpotato using a minimal number of loci.
Marker Saturation of the Region Flanking the Gene NSV Conferring Resistance to the Melon Necrotic Spot Carmovirus (MNSV) in Melon
Authors: Morales Mónica , Luís-Arteaga Marisol , Álvarez José María , Dolcet-Sanjuan Ramon , Monfort Amparo , Arús Pere , Garcia-Mas Jordi
Published: January 2019

The recessive allele (nsv) of the NSV gene confers resistance to the Carmovirus melon necrotic spot virus (MNSV) in melon (Cucumis melo L.). Using an F2 population obtained from the cross between the resistant Korean accession PI 161375 and a susceptible line of `Piel de Sapo', we have mapped the NSV locus to linkage group 11 (G11) of the melon genome. Additional markers closely linked to NSV were developed by bulked segregant analysis (BSA) using a doubled haploid progeny population derived from the same cross. A detailed map of the NSV region was constructed containing 10 markers spanning a distance of 17.7 cM. The nearest flanking markers to NSV were two amplified fragment length polymorphisms (AFLPs) (CTA/ACG-115 and CTA/ACG-120) and one random amplified polymorphic DNA (RAPD) (OPD08-0.80) separated by 5.9 cM. Two more markers, ACC/ACC-110 and OPX15-1.06, cosegregated with NSV.
DNA Markers Linked to Fusarium Wilt Race 1 Resistance in Pea
Authors: McClendon Melissa T. , Inglis Debra A. , McPhee Kevin E. , Coyne Clarice J.
Published: January 2019

Dry pea (Pisum sativum L.) production in many areas of the world may be severely diminished by soil inhabiting pathogens such as Fusarium oxysporum f. sp. pisi race 1, the causal organism of fusarium wilt race 1. Our objective was to identify closely linked marker(s) to the fusarium wilt race 1 resistance gene (Fw) that could be used for marker assisted selection in applied pea breeding programs. Eighty recombinant inbred lines (RILs) from the cross of Green Arrow (resistant) and PI 179449 (susceptible) were developed through single-seed descent, and screened for disease reaction in race 1 infested field soil and the greenhouse using single-isolate inoculum. The RILs segregated 38 resistant and 42 susceptible fitting the expected 1:1 segregation ratio for a single dominant gene (χ2 = 0.200). Bulk segregant analysis (BSA) was used to screen 64 amplified fragment length polymorphism (AFLP) primer pairs and previously mapped random amplified polymorphic DNA (RAPD) primers to identify candidate markers. Eight AFLP primer pairs and 15 RAPD primers were used to screen the RIL mapping population and generate a linkage map. One AFLP marker, ACG:CAT_222, was within 1.4 cM of the Fw gene. Two other markers, AFLP marker ACC:CTG_159 at 2.6 cM linked to the susceptible allele, and RAPD marker Y15_1050 at 4.6 cM linked to the resistant allele, were also identified. The probability of correctly identifying resistant lines to fusarium wilt race 1, with DNA marker ACG:CAT_222, is 96% percent. These markers will be useful for marker assisted breeding in applied pea breeding programs.
Leaf Expansion, Stomatal Conductance, and Transpiration of Vegetable Amaranth (Amaranthus sp.) in Response to Soil Drying
Authors: Liu F. , Stützel H.
Published: January 2019

This study was designed to quantify the responses of leaf expansion, stomatal conductance, and transpiration of four genotypes of vegetable amaranth [Amaranthus tricolor L. (Hin Choi), A. tricolor L. (Co. 2), A. blitum L. (WS80-192), and A. cruentus L. (RRC 1027)] to soil drying. Two greenhouse experiments were conducted during 1999 and 2000. Soil water status was expressed as the fraction of transpirable soil water (FTSW). Leaf expansion rates, stomatal conductances, and transpiration rates of the stressed plants were determined relative to those of nonstressed plants, and expressed as relative leaf expansion (RLE), relative stomatal conductance (RSC), and relative transpiration (RT), respectively. The rate of soil water extraction differed among genotypes, with RRC 1027 depleting soil water fastest and Hin Choi slowest. Whereas in 1999 all genotypes were equally efficient in soil water use, RRC 1027 extracted a greater volume of transpirable soil water than the other genotypes in 2000. The responses of RLE, RSC, and RT to FTSW were well described by linear-plateau models which allowed calculation of soil-water thresholds for leaf expansion (CL), stomatal conductance (CS), and transpiration (CT). Values for CL were higher than for CS and CT. CL was similar for the four genotypes in each year, whereas, CS and CT differed among genotypes. CS and CT was lowest for Hin Choi and highest for WS80-192. Differences of CL, CS, and CT between the two experiments might have been due to the different soils used in the experiments and the different evaporative demands during the drought cycles. Under drought stress, the reduction of transpiration of vegetable amaranth was due mainly to reduction of stomatal conductance, not to reduction of leaf expansion. The relative reduction of dry weight caused by drought stress was positively correlated with CS or CT across the four genotypes. Variation in CS and CT among amaranth genotypes revealed different responses to drought stress, which could make them suitable for different drought situations.
Changes in the Expression of Anthocyanin Biosynthetic Genes during Apple Development
Authors: Kondo Satoru , Hiraoka Kentaro , Kobayashi Shozo , Honda Chikako , Terahara Norihiko
Published: January 2019

Cyanidin 3-galactoside was the primary anthocyanin in red `Tsugaru' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. The concentration of cyanidin 3-galactoside in the skin decreased from 20 to 62 days after full bloom (DAFB), then increased rapidly after 104 DAFB. Small amounts of cyanidin 3-arabinoside and cyanidin 3-glucoside were detected at 122 and 133 DAFB (harvest). The expression of five anthocyanin biosynthetic genes of chalcone synthase (MdCHS), flavanone 3-hydroxylase (MdF3H), dihydroflavonol 4-reductase (pDFR), anthocyanidin synthase (MdANS), and UDP glucose-flavonoid 3-O-glucosyltransferase (pUFGluT) was examined in the skin of red and nonred apples. In general, the expression of anthocyanin biosynthetic genes in red apples was strong in juvenile and ripening stages. The expression of MdCHS, MdF3H, pDFR, and MdANS was observed before ripening stage when anthocyanin was not detected. In contrast, the expression of pUFGluT was detected in the development stage only when anthocyanin was detected. However, the expression of all five genes was observed at 20 DAFB in fruit bagged after fertilization, and anthocyanin was not detected. The expression of MdCHS, MdF3H, pDFR, and MdANS, excluding pUFGluT, was detected at 98 DAFB in fruit bagged after 30 DAFB, and anthocyanin was not detected. These results suggest that pUFGluT may be closely related to the anthocyanin expression in apple skin at the ripening stage.
Patterns of Floral Bud Development in Canes of Erect and Trailing Blackberries
Authors: Takeda Fumiomi , Strik Bernadine C. , Peacock Derek , Clark John R.
Published: January 2019

Flower bud development was studied in `Cherokee', `Boysen', and `Marion' blackberries (Rubus subgenus Rubus Watson). In `Cherokee' (erect type), the transition to reproductive development in buds on the branch canes occurred during September in Arkansas and Oregon. Transitions of buds in the axils of the most basal nodes (proximal to the main cane) and the most distal nodes lagged behind buds in the midsection (about nodes 6 to 10). Along the midsection of branch canes, the buds developed uniformly. In buds of `Boysen' and `Marion' (trailing type), the transition to reproductive development occurred in October and sepal primordia were observed in most buds examined by November. Progression of floral bud development continued into January, but at a slower rate than in autumn. Buds on the main canes (>3 m long) of `Boysen' and `Marion' remained at a more advanced stage of flower bud differentiation than buds on the basal branch canes. In both cultivars, buds from the middle one-third section, and sometimes buds from the bottom one-third section, tended to be more advanced than those buds in the top one-third section during much of the sampling period. The results suggest that rate and patterns of flower bud development vary among cultivars grown in different locations. However, the pattern of flower bud development was not in a basipetal fashion on main or branch canes.
Cytological and Ultrastructural Evaluations of Zinc Deficiency in Leaves
Authors: Kim Tehryung , Wetzstein Hazel Y.
Published: January 2019

Zinc deficiency is a widespread nutritional disorder in plants and occurs in both temperate and tropical climates. In spite of its physiological importance, cytological and ultrastructural changes associated with zinc deficiency are lacking, in part because zinc deficiency is difficult to induce. A method was developed to induce zinc deficiency in pecan (Carya illinoinensis (Wangenh.) C. Koch) using hydroponic culture. Zinc deficiency was evaluated in leaves using light and electron microscopy. Zinc deficiency symptoms varied with severity ranging from interveinal mottling, overall chlorosis, necrosis, and marginal curving. Zinc deficient leaves were thinner, and palisade cells were shorter, wider, and had more intercellular spaces than zinc sufficient leaves. Cells in zinc deficient leaves had limited cytoplasmic content and accumulated phenolic compounds in vacuoles. Extensive starch accumulation was observed in chloroplasts. This work represents the first detailed microscopic evaluations of zinc deficiency in leaves, and provides insight on how zinc deficiency affects leaf structure and function.
Effect of Artificial Shading and Temperature on Radical Scavenging Activity and Polyphenolic Composition in Sweetpotato (Ipomoea batatas L.) Leaves
Authors: Islam Md. Shahidul , Yoshimoto Makoto , Ishiguro Koji , Okuno Shigenori , Yamakawa Osamu
Published: January 2019

The phenolic content and the radical scavenging activity were compared in leaves of sweetpotato (Ipomoea batatas L.) cultivars Shimon-1, Kyushu-119 and Elegant Summer grown under different temperature and shading conditions. Compared to cultivar differences, there was less effect of temperature and shading on the total phenolic content in sweetpotato leaves, however certain polyphenolic components differed widely among the treatments. The positive correlation between the radical scavenging activity and the level of total phenolics (r = 0.62) suggests that phenolic compounds are important antioxidant components of sweetpotato leaves. All the reverse-phase high-performance liquid chromatography (RP-HPLC) profiles of the cultivars tested showed peaks at the same retention times but peak areas of individual phenolic compounds differed with respective temperature and shading treatments. The phenolic compounds identified in the sweetpotato leaf were caffeic acid, chlorogenic acid, 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, 3,4-di-O-caffeoylquinic acid, and 3,4,5-tri-O-caffeoylquinic acid. Most of the phenolic compounds were highest in leaves from plants grown at 20 °C without shading except 4,5-di-O-caffeoylquinic acid. The results indicate that growing leaves under moderately high temperatures and in full sun enhances the accumulation of phenolic components. These phenolic components have possible value in enhancing human health.
Genotypic Variation in Abscisic Acid Accumulation, Water Relations, and Gas Exchange for Kentucky Bluegrass Exposed to Drought Stress
Authors: Wang Zhaolong , Huang Bingru
Published: January 2019

Drought is a major limiting factor for turfgrass growth. Understanding genetic variations in physiological responses of turfgrass to drought stress would facilitate breeding and management programs to improve drought resistance. This study was designed to evaluate responses of abscisic acid (ABA) accumulation, water relations, and gas exchange to drought stress in four Kentucky bluegrass (Poa pratensis L.) cultivars differing in drought resistance. Plants of `Midnight' and `A82-204' (drought resistant) and `Brilliant' and `RSP' (drought susceptible) were grown under well-watered (control) or drought stress conditions for 25 days in growth chambers. Turf quality, leaf water potential (Ψleaf), relative water content (RWC), leaf net photosynthesis rate (Pn), and stomatal conductance (gs) declined, while electrolyte leakage (EL) increased during drought progression in all cultivars. The magnitudes of the change in these parameters were greater for `RSP' and `Brilliant' than for `Midnight' and `A82-204'. Leaf ABA content in `RSP' and `Brilliant' increased sharply after 2 days of stress to as much as 34 times the control level at 10 days of drought. Leaf ABA content in `Midnight' and `A82-204' also increased with drought, but to a lesser extent than in the other two cultivars. Leaf ABA level was negatively correlated with Ψleaf and gs. `A82-204' had a significantly lower ABA accumulation rate with changes in Ψleaf during drought compared to `Midnight', `RSP' and `Brilliant'; however, no differences in ABA accumulation rate were detected among the latter three cultivars. In addition, leaf gs was more sensitive to changes in ABA accumulation in `Midnight' and `A82-204' than in `RSP' and `Brilliant'. These results demonstrated that drought tolerant cultivars of Kentucky bluegrass were characterized by lower ABA accumulation and less severe decline in Ψleaf, Pn, gs, and turf quality during drought stress than drought sensitive cultivars. Drought tolerance of Kentucky bluegrass could be related to sensitivity of stomata to endogenous accumulation of ABA under drought stress conditions.
Selection for Increased Budbreak in Apple
Authors: Labuschagné Iwan F. , Louw J.H. , Schmidt Karin , Sadie Annalene
Published: January 2019

Significant response to selection for budbreak number (NB) based on data recorded on 1-year-old shoots of young apple (Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.) seedlings (Expt. I) and branches from adult seedling trees (Expt. II) has been demonstrated in clonally propagated seedling trees. Between family variation for NB was low and masked by year × family interaction effects. Realized heritability for NB was estimated as 40% to 60%. Correlated response in uniformity and position of budbreak, and in the number and length of side shoots, was found. Association between the time of budbreak (TB) and NB, according to midparent and cross groupings, and according to the parental means, indicate a positive genetic correlation between these traits. Where data on adult trees were used as a measure of selection response and tested on young clonal trees, significant response and genetic variation was shown, confirming the presence of utilizable genetic variance and that this procedure may be successfully applied as an early screening method for increased budbreak in adult trees. Combined selection utilizing genetic variance between crosses as well as within crosses is proposed as the best procedure to increase the frequency of seedlings with increased budbreak and to improve adaptation to low winter chilling conditions.
Statistical Model Estimates Potential Yields in Pear Cultivars `Blanquilla' and `Conference' before Bloom
Authors: Jiménez Carlos Miranda , Díaz J. Bernardo Royo
Published: January 2019

Spring frosts are usual in many of Spain's fruit-growing areas, so it is common to insure crops against frost damage. After a frost, crop loss must be evaluated, by comparing what crop is left with the amount that would have been obtained under normal conditions. Potential crop must be evaluated quickly through the use of measurements obtainable at the beginning of the tree's growth cycle. During 1996 and 1997 and in 95 commercial plots of `Blanquilla' and `Conference' pear (Pyrus communis L.), the following measurements were obtained: trunk cross-sectional area (TCA, cm2), space allocated per tree (ST, m2), trunk cross-sectional area per hectare (TCA/ha), flower density (FD, number of flower buds/cm2 TCA), flower density per land area (FA, number of flower buds/m2 land area), cluster set (CS, number of fruit clusters/number of flower clusters, %), crop density (CD, number of fruit/cm2 TCA), fruit clusters per trunk cross-sectional area (FCT, number of fruit clusters/cm2 TCA), fruit clusters per land area (FCA, number of fruit clusters/m2 land area), fruit number per cluster (FNC), average fruit weight (FW, g), average yield per fruit cluster (CY, g), yield efficiency (YE, fruit g·cm-2 TCA), and tree yield (Y, fruit kg/tree). CS and average CY were related to the rest of the variables through the use of multiple regression models. The models that provided the best fit were CS = TCA/ha - FA and CY = -FA - FCT. These models were significant, consistent, and appropriate for both years. Predicted yield per land area was obtained by multiplying FA × CS × CY. The models' predictive ability was evaluated for 46 different plots in 2001 and 2002. Statistical analysis showed the models to be valid for the forecast of orchards' potential yield efficiency, so that they represent a useful tool for early crop prediction and evaluation of losses due to late frosts.
Heterogeneity of Segregation Ratios from Selfed Progenies Demonstrate Polygenic Inheritance for Day Neutrality in Strawberry (Fragaria ×ananassa Duch.)
Authors: Shaw Douglas V.
Published: January 2019

Selfed progenies were generated using 10 day-neutral genotypes from the University of California (UC) strawberry breeding program as parents and their offspring were classified for late-summer flowering response. The grandparents of each selfed progeny included one of four day-neutral genotypes and one of eight short-day genotypes. Under the null hypothesis of genetic control by a single locus with the allele for day-neutrality dominant to the allele for short-day flowering response, all of these day-neutral parent genotypes must be heterozygous and their selfed offspring were expected to fit a 3:1 ratio of day-neutral: short-day phenotypes. The percentage of day-neutral offspring observed over all progenies was 70.9%, and was significantly smaller than the expected value of 75% (χ21 = 5.08, P < 0.02). The percentage of day-neutral offspring for individual progenies ranged from 41.4% to 84.8%, and highly significant heterogeneity was detected among progenies (χ29 = 40.3, P < 0.01). Selfed progeny means for the cumulative late-summer flowering score calculated using the day-neutral fraction of offspring varied from 1.31 to 2.35 and progeny means for the number of inflorescences per plant ranged from 3.5 to 9.9; these differences among progenies were highly significant (P < 0.01). These observations can be used to conclusively reject the hypothesis that day-neutrality in this domestic strawberry population is controlled by a single locus.
Mapping and Evaluation of Malus ×domestica Microsatellites in Apple and Pear
Authors: Hemmat Minou , Weeden Norman F. , Brown Susan K.
Published: January 2019

We mapped DNA polymorphisms generated by 41 sets of Simple Sequence Repeat (SSR) primers, developed independently in four laboratories. All primer sets gave polymorphisms that could be located on our `White Angel' x `Rome Beauty' map for apple [Malus sylvestris (L.) Mill. Var. domestica (Borkh.) Mansf.]. The SSR primers were used to identify homologous linkage groups in `Wijcik McIntosh', NY 75441-58, `Golden Delicious', and `Liberty' cultivars for which relatively complete linkage maps have been constructed from isozyme and Random Amplified Polymorphic DNA (RAPD) markers. In several instances, two or more SSRs were syntenic, and except for an apparent translocation involving linkage group (LG) 6, these linkages were conserved throughout the six maps. Twenty-four SSR primers were consistently polymorphic, and these are recommended as standard anchor markers for apple maps. Experiments on a pear (Pyrus communis L.) population indicated that many of the apple SSRs would be useful for mapping in pear. However some of the primers produced fragments in pear significantly different in size than those in apple.
Thermostability of Cell Membranes as a Measure of Heat Tolerance and Relationship to Flowering Delay in Chrysanthemum
Authors: Yeh D.M. , Lin H.F.
Published: January 2019

Identification of heat-tolerant chrysanthemum [Dendranthema ×grandifolia (Ramat.) Kitamura] genotypes for commercial production in hot areas of the world is desirable. The extent to which electrolyte leakage from chrysanthemum leaf discs, measured using a test for cell membrane thermostability (CMT), could be related to the delay in flowering induced by heat in the field-grown plants was determined. The relationship between the relative injury (RI) occurring in leaf tissue discs of chrysanthemum cultivars and treatment temperature was sigmoidal. A single temperature treatment at 50 °C resulted in injury values near the midpoint of the sigmoidal response curve and showed the greatest sensitivity in detecting genotypic differences in heat tolerance. The cultivars with a low RI value are those with the greater CMT and shorter heat-induced delay to flowering.