bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromosome Identification and Karyotyping of Satsuma Mandarin by Genomic In Situ Hybridization
Authors: Kitajima Akira , Yamasaki Atsu , Habu Tsuyoshi , Preedasuttijit Bannarat , Hasegawa Kojiro
Published: January 2019

Satsuma mandarin (Citrus unshiu Marcow.) chromosomes were stained with Giemsa and fluorochromes chromomycin A3 (CMA)/4′,6-diamidino-2-phenyindole (DAPI). Eighteen chromosomes were categorized into eight groups by the position and relative size of the CMA (+) region and relative length of chromosome. Ponkan (C. reticulata Blanco) DNA labeled with Dig-rhodamine (red) and pummelo [C. maxima (Burm.) Merr.] DNA labeled with biotin-fluorescein isothiocyanate (green) were used as genomic in situ hybridization (GISH) probes. GISH signals were detected on CMA (+) regions and other heterochromatin blocks. The chromosomes were categorized into 12 groups by the coloration and size of GISH signals with relative length of chromosomes. GISH allowed six pairs of speculated homozygous and six individual heterozygous chromosomes of satsuma mandarin to be identified unambiguously. In 10 chromosomes with distinct GISH signals on the CMA (+) regions, red GISH signals were detected on nine chromosomes, indicating that satsuma mandarin is closely related to ponkan. Two colors (red and green) of GISH signals were detected on type C chromosome and three different colors (red, green, and yellow) were detected on type A, indicating that pummelo is involved in the origin of satsuma mandarin. The origins of types A and C chromosomes in satsuma mandarin were also discussed. This article demonstrates that GISH is a powerful tool for chromosome identification and karyotyping in citrus.
Evaluation of Elite Native Strawberry Germplasm for Resistance to Anthracnose Crown Rot Disease Caused by Colletotrichum Species
Authors: Lewers K.S. , Turechek W.W. , Hokanson S.C. , Maas J.L. , Hancock J.F. , Serçe S. , Smith B.J.
Published: January 2019

Anthracnose crown rot of cultivated strawberry (Fragaria ×ananassa Duchesne ex Rozier) has been a major disease problem in the strawberry producing regions of the southeastern United States since the early 1970s. Chemical controls are often inadequate, but use of resistant cultivars is seen as a credible option for managing this disease. Only a small portion of Fragaria L. germplasm has been screened for resistance to anthracnose crown rot. A core subset of the Fragaria collection maintained at the U.S. Department of Agriculture National Clonal Repository in Corvallis, OR, has been constructed to contain an elite group of native F. virginiana Mill. and F. chiloensis (L.) Mill. This collection, referred to as the “core collection,” has been characterized for many horticultural traits, including reactions to several common foliar diseases, resistance to black root rot (causal organisms unknown), and resistance to northern root-knot nematode (Meloidogyne hapla Chitwood) and root-lesion nematode [Pratylenchus penetrans (Cobb) Filipjev & Shuurmans Stekhoven]. Our objective was to evaluate the core collection for resistance to a selection of isolates of three Colletotrichum Corda species known to cause strawberry anthracnose, Colletotrichum fragariae A.N. Brooks, Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. [teleomorph Glomerella cingulata (Stoneman) Spauld. & H. Schrenk], and Colletotrichum acutatum J.H. Simmonds (teleomorph Glomerella acutata J.C. Guerber & J.C. Correll). No Fragaria subspecies or geomorph was more resistant than any other; rather, individual genotypes within these groups were identified as sources from which resistance can be obtained. Collecting germplasm in areas of intense disease pressure may not be as beneficial as one might assume, at least where anthracnose crown rot disease is concerned.
Plum Pox Virus Coat Protein Gene Intron-hairpin-RNA (ihpRNA) Constructs Provide Resistance to Plum Pox Virus in Nicotiana benthamiana and Prunus domestica
Authors: Hily Jean-Michel , Ravelonandro Michel , Damsteegt Vern , Bassett Carole , Petri Cesar , Liu Zongrang , Scorza Ralph
Published: January 2019

Constructs with self-complementary sequences separated by an intron produce “hairpin” RNA [intron-hairpin-RNA (ihpRNA)] structures that efficiently elicit posttranscriptional gene silencing (PTGS). In the current study, the authors use this technology to confer resistance to plum pox virus (PPV) in herbaceous and woody perennial plants by silencing the PPV–coat protein (CP) gene. The authors confirmed the high capacity of ihpRNA constructs for inducing RNA silencing in Nicotiana benthamiana Domin., as more than 75% of the transformants displayed PTGS as evaluated by specific small interfering RNA (siRNA) production. The authors demonstrated that ihpRNA constructs provided PPV resistance, and they found a correlation between the length of the PPV sequence introduced in the ihpRNA constructs and the frequency of transgenic-resistant plants. Plants transformed with the full-length sequence produced a higher percentage of resistant lines. The authors further demonstrated for the first time that ihpRNA technology is applicable to a woody perennial species. A transgenic plum (Prunus domestica L.) PPV-CP ihpRNA line showed gene silencing characteristics (hypermethylation of the transgene sequence and specific siRNA production) and resistance to PPV infection 16 months after inoculation.
Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids
Authors: Bolaños-Villegas Pablo , Chin Shih-Wen , Chen Fure-Chyi
Published: January 2019

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.
Induction of Seedlessness in Citrus: From Classical Techniques to Emerging Biotechnological Approaches
Authors: Vardi Aliza , Levin Ilan , Carmi Nir
Published: January 2019

Seedlessness can be obtained through parthenocarpy (i.e., fruit formation without fertilization or embryo abortion). In practice, the actual reduction in seed number in parthenocarpic plants is often exaggerated by coupling parthenocarpy with self-incompatibility or male sterility. Traits related to seedlessness, such as parthenocarpy, can be introduced into genetic accessions through conventional cross-breeding. However, conventional breeding in Citrus L. species faces several limitations. First, these species have long juvenile (nonflowering) periods during which a relatively thick canopy develops, which limits the size of seedling populations that can be maintained for further evaluation. Second, they have a narrow genetic base, which limits the availability of alternative alleles that could be introgressed into other lines for the formation of a particular phenotype such as parthenocarpy. Third, breeding efforts are limited by the lack of knowledge of the mode of inheritance of specific characteristics. Fourth, and last, breeding efforts are limited by the polygenic nature of many important traits. Despite these limitations, conventional breeding in fruit trees has yielded improved cultivars and will most likely continue to be a very important strategy. However, emerging biotechnological approaches should be continuously evaluated for their potential for expediting such breeding efforts. The objective of this review is to present, evaluate, and discuss conventional and emerging biotechnological approaches for the induction and maintenance of seedlessness in a variety of crops. Particular attention will be paid to citrus crops, including the presentation and discussion of some preliminary data on the genetic inheritance of parthenocarpy.
The Relationship Between Flower and Fruit Abscission and Alternate Bearing of ‘Hass’ Avocado
Authors: Garner Lauren C. , Lovatt Carol J.
Published: January 2019

Despite profuse flowering, ‘Hass’ avocado (Persea americana Mill.) yields are low because of excessive flower and fruit abscission. Whether the dynamics of flower and fruit abscission are influenced by or contribute to alternate bearing, the production of a heavy on-crop followed by a light off-crop that is characteristic of many avocado cultivars, remains unresolved. The objective of this research was to determine whether abscission of reproductive structures from ‘Hass’ avocado trees during specific developmental stages, including flowering, fruit development, and fruit maturity, was influenced by crop status of the current or preceding year. Abscised reproductive structures were collected from commercially bearing trees during two complete crop years. Flower abscission began at about the same time but peaked 1 month later in the off-crop year compared with the on-crop year. Peak abscission rates were lower during the off-crop year than the on-crop year (compare 1836 ± 403 to 5378 ± 856 flowers per day and 50 ± 18 to 280 ± 23 immature fruit per day, respectively). The off- or on-crop status of the tree did not influence the percentage fruit set, average fruit diameter, or biomass of individual fruit that abscised at similar phenological stages. Furthermore, flower and fruit abscission were not influenced by the number of mature fruit from the previous year's crop. In both years of the research, as immature fruit abscission declined, abscission of the preceding year's crop increased, indicating that the processes were controlled independently. During the study, neither weather conditions nor tree nutrient status were associated with key abscission events. Taken together, these results provide evidence that the previous year's yield does not influence flower or fruit abscission and the seasonal abscission of reproductive structures is an independent process that does not contribute to alternate bearing of ‘Hass’ avocado.
An Integrated Molecular Map of Yellow Passion Fruit Based on Simultaneous Maximum-likelihood Estimation of Linkage and Linkage Phases
Authors: Oliveira Eder J. , Vieira Maria Lucia C. , Garcia Antonio Augusto F. , Munhoz Carla F. , Margarido Gabriel R.A. , Consoli Luciano , Matta Frederico P. , Moraes Michel C. , Zucchi Maria I. , Fungaro Maria Helena P.
Published: January 2019

The development of genetic maps for auto-incompatible species, such as the yellow passion fruit (Passiflora edulis Sims f. flavicarpa Deg.) is restricted due to the unfeasibility of obtaining traditional mapping populations based on inbred lines. For this reason, yellow passion fruit linkage maps were generally constructed using a strategy known as two-way pseudo-testcross, based on monoparental dominant markers segregating in a 1:1 fashion. Due to the lack of information from these markers in one of the parents, two individual (parental) maps were obtained. However, integration of these maps is essential, and biparental markers can be used for such an operation. The objective of our study was to construct an integrated molecular map for a full-sib population of yellow passion fruit combining different loci configuration generated from amplified fragment length polymorphisms (AFLPs) and microsatellite markers and using a novel approach based on simultaneous maximum-likelihood estimation of linkage and linkage phases, specially designed for outcrossing species. Of the total number of loci, ≈76%, 21%, 0.7%, and 2.3% did segregate in 1:1, 3:1, 1:2:1, and 1:1:1:1 ratios, respectively. Ten linkage groups (LGs) were established with a logarithm of the odds (LOD) score ≥ 5.0 assuming a recombination fraction ≤0.35. On average, 24 markers were assigned per LG, representing a total map length of 1687 cM, with a marker density of 6.9 cM. No markers were placed as accessories on the map as was done with previously constructed individual maps.
Segregations for Onion Bulb Colors Reveal That Red Is Controlled by at Least Three Loci
Authors: Khar Anil , Jakse Jernej , Havey Michael J.
Published: January 2019

Onion (Allium cepa L.) bulb color is controlled by at least five major loci (I, C, G, L, and R) and seedcoat color by one locus (B). The authors developed families segregating for bulb and seedcoat colors, simple sequence repeats (SSRs), and single nucleotide polymorphisms (SNPs) in genomic amplicons of dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS). The B and C loci were linked to SSRs on chromosomes 1 and 6 respectively. For all of three families, SNPs in DFR cosegregated with the R locus conditioning red bulb color. In the family from B2246 × B11159, red bulbs versus yellow bulbs were controlled by DFR and a locus (L2) linked at 6.3 cM to ANS. The authors propose that yellow bulb onions have been independently selected numerous times and that yellow populations carry independent mutations in structural or regulatory genes controlling the production of red bulb color in onion.
Combined Analysis of S-Alleles in European Pear by Pollinations and PCR-based S-Genotyping; Correlation between S-Phenotypes and S-RNase Genotypes
Authors: Sanzol Javier , Robbins Timothy P.
Published: January 2019

Pollen–pistil incompatibility in european pear (Pyrus communis L.) compromises adequate orchard pollination and fruit set and restricts cross-fertility between cultivars suitable as parents in breeding programs. Genetic control is simple, with a single locus expressed gametophytically in pollen controlling the rejection of the pollen tube in the style. Semicompatible pollination arises when only one allele of a pollen parent matches the pistil. Semicompatible test-crosses using partially S-genotyped european pear cultivars allowed the discrimination of 14 S-alleles (S1 to S14) at the phenotypic level and the assignment of 33 cultivars to 13 incompatibility groups. Partial genomic sequences of the S-RNase gene, spanning between the C1 and C5 conserved regions, were obtained for each new S-allele identified (S6 to S14). These sequences and those reported previously for the S1 to S5 RNases allowed a set of consensus primers amplifying all 14 S-RNase alleles to be designed. Allele-specific PCR allowed discrimination between those S-RNases giving amplification products of similar size with consensus primers. These two approaches provided a method for the molecular identification of all 14 S-alleles in european pear. With this methodology, we demonstrate that the S-RNase genotypes inferred from PCR exactly matches the S-phenotypes deduced from test-crosses. Comparison of the sequences obtained with those of S-RNases already published allowed us to relate S-alleles between studies. This will allow the prediction of cross-incompatibility among an even larger number of european pear cultivars.
Genetic Diversity and Differentiation among Natural, Production, and Introduced Populations of the Narrowly Endemic Species Coreopsis leavenworthii (Asteraceae)
Authors: Czarnecki David M. , Nageswara Rao Madhugiri , Norcini Jeffrey G. , Gmitter Frederick G. , Deng Zhanao
Published: January 2019

Seeds of Coreopsis leavenworthii Torr. & Gray (Asteraceae) are being commercially produced but the lack of genetic diversity information has hindered growers and end users from addressing several critical issues affecting wild collection, commercial production, distribution, and the use of seeds. In this study, the genetic diversity and differentiation among natural, production, and introduced populations were analyzed at the molecular level using 320 amplified fragment length polymorphism (AFLP) markers. A high level of diversity [68.6% average polymorphism; total genetic diversity (H

t
) = 0.309] and a moderate level of genetic differentiation [total genetic diversity residing among populations (G

st
) = 0.226; Φ
st
= 0.244; Bayesian analog of Nei's G

st
(G

st
-B) = 0.197] was detected among six natural populations—two each from northern, central, and southern Florida. Two distance-based clustering analyses, based on an individual's AFLP phenotypes or a population's allele frequencies, grouped natural populations into three clusters, concordant with our previous results from a common garden study of phenotypic variation. Clustering of populations was mostly according to their respective geographical origin within Florida. The correlation between geographical distances and pairwise F

st
values between populations was very significant (r = 0.855, P < 0.0001). Two central Florida natural populations were divergent and grouped into separate clusters, indicating that the existence of factors other than physical distance alone were contributing to genetic isolation. Three production populations maintained a level of genetic diversity comparable to that in the natural populations and were grouped with the natural populations from which the production populations were derived, suggesting that the genetic identity of the seed origin was maintained under production practices. The genetic diversity of the introduced population was comparable to that of the source populations (central Florida natural populations), but genetic shift seems to have occurred, causing the introduced population to cluster with local (northern Florida) populations where planted. The observed genetic differentiation among natural populations may indicate a need to develop appropriate zones within Florida for preservation of genetic diversity during seed collection, increase, and distribution. This high level of population differentiation also suggests a need to collect and analyze more natural populations across Florida and from Alabama for a better understanding of the species' genetic diversity and population structure across its distribution range.
Differential Protein Expression of Two Photosystem II Subunits, PsbO and PsbP, in an Albino Mutant of Bambusa edulis with Chloroplast DNA Aberration
Authors: Lin Choun-Sea , Liu Nien-Tzu , Liao De-Chih , Yu Jau-Song , Tsao Chuang-Hwei , Lin Chao-Hsiung , Sun Chih-Wen , Jane Wann-Neng , Tsay Hsing Sheng , Jian-Wei Chen Jeremy , Lai Erh-Min , Lin Na-Sheng , Chang Wei-Chin , Lin Chung-Chih
Published: January 2019

The chloroplast genome of an albino mutant isolated from tissue culture of the bamboo Bambusa edulis Munro was examined to identify aberrations. A number of the chloroplast genes encoding ATP synthases, photosystem II subunits, NADH dehydrogenase, and ribosomal proteins had been deleted, at least partially, in the albino mutant. Comparison of the two-dimensional electrophoresis profiles of albino and green bamboos revealed three spots of reduced intensity, indicating repression of these proteins in the albino mutants. Mass spectroscopic analysis subsequently revealed that two of these proteins are 33-kDa subunits of the photosystem II oxygen-evolving protein complex (PsbO) and one is a 23-kDa subunit of photosystem II oxygen-evolving protein complex (PsbP). The genes encoding these two proteins were cloned from B. edulis, and were denoted BePsbO (accession no. EF669513) and BePsbP (accession no. EF669512). Reverse transcription polymerase chain reaction and two-dimensional gel analyses of BePsbO and BePsbP in green and albino bamboos grown in the light or dark revealed that the albino mutant, similar to its green counterpart, sensed the light signal, resulting in the induction of BePsbO and BePsbP transcription, but it did not accumulate the protein products. We conclude that the repression of protein-expressing BePsbO and BePsbP is because of a defect in post-transcriptional regulation in the albino mutant.
Inheritance of Phenological, Vegetative, and Fruit Chemistry Traits in Black Raspberry
Authors: Dossett Michael , Lee Jungmin , Finn Chad E.
Published: January 2019

In recent years, there has been renewed interest in black raspberry (Rubus occidentalis L.) breeding. This has been spurred by an increase in black raspberry consumption resulting from studies that have shown them to be particularly high in anthocyanin content indicating high levels of antioxidants. Present cultivars are ill-adapted to the biotic and abiotic stresses of the Pacific northwestern United States, where the commercial black raspberry industry is centered, and fields must be replanted after three to five seasons. An incomplete partial diallel, consisting of 10 parents and 26 sibling families, was constructed for the study of variation and inheritance of phenological, vegetative, and fruit chemistry traits in black raspberry. Sibling families were established at the Oregon State University Lewis Brown Farm in Corvallis and were arranged as a randomized complete block design with four blocks of one to eight plants. Phenological development and vegetative measurements were recorded for each plant in 2005 and 2006. In addition, 25-berry samples of ripe fruit were collected from each plant. To study variation in fruit chemistry properties, including pH, titratable acidity, percent soluble solids, anthocyanin profiles, and total anthocyanins, additional samples of 25 ripe berries were collected from each plant and pooled by family within blocks. Although there were many striking similarities, strong trends in phenotype based on pedigree were observed for most traits indicating a strong genetic component. General combining ability (GCA) effects were significant and larger than specific combining ability effects for all traits, except for fruit size (mass). With the exception of fruit size, narrow-sense heritability estimates were generally moderate to high (0.30 to 0.91), indicating the potential for breeding progress within the population of plants studied. Despite these results, statistically significant and large GCA values were limited to just a few of the parents, indicating a lack of heritable genetic variation in much of the germplasm base and a need for greater diversity.
Genetics of Root System Architecture Using Near-isogenic Lines of Melon
Authors: Fita Ana , Picó Belén , Monforte Antonio J. , Nuez Fernando
Published: January 2019

The study of the genetic control of natural variation in the root architecture of Cucumis melo L. is complex due to the difficulties of root phenotyping and to the quantitative nature of root traits and their plasticity. A library of near-isogenic lines (NILs), constructed by introgressing the genome of the exotic Korean accession Shongwan Charmi [SC (PI161375)] into the genetic background of the cultivar Piel de Sapo (PS) has recently become available. In this work, we used this population to identify quantitative trait loci (QTLs) controlling variation in root growth and architecture. We studied separately the primary root and the secondary and tertiary root systems during a 15-day period. Heritabilities for the root traits were moderate. Correlation and principal component analysis showed independence among traits measuring root length and root branching level, indicating the possibility of modifying both traits independently. PS and SC clearly differed in plant size. Significant allometric relationships between vine biomass and some root traits were identified. The use of NILs with similar plant size of PS allowed us to avoid the inaccuracies caused by size-dependent variation of root traits. A total of 17 QTLs for root traits in seven linkage groups were identified: three QTLs for primary root length, three QTLs for the diameter of the primary root, three QTLs for secondary root density, three QTLs for the average length of the secondary roots, three QTLs for the percentage of secondary roots bearing tertiary roots, and two QTLs for tertiary root density. In most of these traits, transgressive variation was observed.
DGTF: A Database of Grape Transcription Factors
Authors: Cai Bin , Li Cheng-Hui , Xiong Ai-Sheng , Peng Ri-He , Zhou Jun , Gao Feng , Zhang Zhen , Yao Quan-Hong
Published: January 2019

The database of grape transcription factors (DGTF) is a plant transcription factor (TF) database comprehensively collecting and annotating grape (Vitis L.) TF. The DGTF contains 1423 putative grape TF in 57 families. These TF were identified from the predicted wine grape (Vitis vinifera L.) proteins from the grape genome sequencing project by means of a domain search. The DGTF provides detailed annotations for individual members of each TF family, including sequence feature, domain architecture, expression information, and orthologs in other plants. Cross-links to other public databases make its annotations more extensive. In addition, some other transcriptional regulators were also included in the DGTF. It contains 202 transcriptional regulators in 10 families.
Substrate Acidification by Geranium: Temperature Effects
Authors: Taylor Matthew D. , Nelson Paul V. , Frantz Jonathan M.
Published: January 2019

Sudden pH decline (SPD) describes the situation where crops growing at an appropriate pH rapidly (within 1–2 weeks) cause the substrate pH to shift downward one to two units. ‘Designer Dark Red’ geraniums (Pelargonium ×hortorum Bailey) were grown in three experiments to assess possible effects of temperature on SPD. The first experiment tested the effect of four day/night temperature regimes (14 °C day/10 °C night, 18 °C day/14 °C night, 22 °C day/18 °C night, and 26 °C day/22 °C night) on substrate acidification. At 63 days after transplanting (DAT), substrate pH declined from 6.8 to 4.6 as temperature increased. Tissue phosphorus (P) of plants grown at the highest three temperatures was extremely low (0.10%–0.14% of dry weight), and P stress has been reported to cause acidification. It was not possible to determine if the drop in substrate pH was a singular temperature effect or a combination of high temperature and low P. To resolve this, a second experiment tested a factorial combination of the three highest temperatures from the first experiment and five preplant P rates (0, 0.065, 0.13, 0.26, or 0.52 g·L−1 substrate). Regardless of tissue P concentrations, which ranged from deficient to above adequate, substrate pH decreased with increasing temperature. At 63 DAT, in the 0.065 and 0.13 P treatments, tissue P was deficient and pH decreased with increasing temperature from 5.6 to 4.7 and 5.9 to 4.7, respectively. In the 0.26 P treatment, tissue P was adequate at the lowest temperature and there was no acidification. At the mid- and highest temperatures, tissue P was deficient and statistically equivalent, yet pH decreased to 5.2 and 4.7, respectively. In the highest P treatment, tissue P levels were unaffected by temperature, above adequate, and pH declined with each increase in temperature from 6.5 to 5.0. The results at 63 DAT once more showed that temperature acted independent of tissue P and caused geraniums to acidify the substrate. In the third experiment, the amount of acidity produced by roots of plants grown at the two highest temperatures used in the first two experiments was quantified. Plants grown at the higher temperature produced 28% more acid per gram dry root. The results herein indicate that high temperature can induce SPD by geranium.
Efficiency of Volatile Formaldehyde Removal by Indoor Plants: Contribution of Aerial Plant Parts versus the Root Zone
Authors: Kim Kwang Jin , Kil Mi Jung , Song Jeong Seob , Yoo Eun Ha , Son Ki-Cheol , Kays Stanley J.
Published: January 2019

The contribution of aerial plant parts versus the root zone to the removal of volatile formaldehyde by potted Fatsia japonica Decne. & Planch. and Ficus benjamina L. plants was assessed during the day and night. The removal capacity of the entire plant, aerial plant parts, and root zone was determined by exposing the relevant parts to gaseous formaldehyde (2 μL·L−1) in airtight chambers (1.0 m3) constructed of inert materials. The rate of formaldehyde removal was initially rapid but decreased as the internal concentration diminished in the chamber. To compare the removal efficiency between species and plant parts, the time interval required to reach 50% of the initial concentration was determined (96 and 123 min for entire plants of F. japonica and F. benjamina, respectively). In both species, the aerial plant parts reduced the formaldehyde concentration during the day but removed little during the night. However, the root zone eliminated a substantial amount of formaldehyde during the day and night. The ratio of formaldehyde removal by aerial plant parts versus the root zone was similar for both species, at ≈1:1 during the day and 1:11 at night. The effectiveness of the root zone in formaldehyde removal was due primarily to microorganisms and roots (≈90%); only about 10% was due to adsorption by the growing medium. The results indicate that the root zone is a major contributor to the removal of formaldehyde. A better understanding of formaldehyde metabolism by root zone microflora should facilitate maximizing the phytoremediation efficiency of indoor plants.
Morphological, Physiological, and Anatomical Characteristics Associated with Heat Preconditioning and Heat Tolerance in Salvia splendens
Authors: Natarajan Seenivasan , Kuehny Jeff S.
Published: January 2019

Many bedding plant cultivars struggle to survive in high temperatures during production. The objective of this research was to study how heat stress and preconditioning affects growth, physiology, and anatomy of the annual bedding plant Salvia splendens Ker Gawl. Heat preconditioning increased the quality and survival capacity of nonheat-tolerant ‘Sizzler Red’. Heat-tolerant traits of ‘Vista Red’ were enhanced with preconditioning. The higher tolerance levels with and without heat preconditioning for ‘Vista Red’ suggested that cultivars with thicker, broader leaves, and higher stomatal frequency had higher light interception, gas exchange, transpirational cooling, and CO2 fixation. These plants attained a more rapid canopy cover and maintained healthier leaves and supplied photoassimilates to reproductive development and root growth. Selecting for these characteristics could be used to help provide guidelines for breeding and selection of heat-tolerant salvia.
Bermudagrass Freezing Tolerance Associated with Abscisic Acid Metabolism and Dehydrin Expression during Cold Acclimation
Authors: Zhang Xunzhong , Wang Kehua , Ervin Erik H.
Published: January 2019

Recent advances in bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon] breeding and cultural management practices have enabled its use as a sports surface in U.S. Department of Agriculture cold hardiness zones 5 and 6. Use of these more cold-hardy bermudagrass cultivars further into transition- and cool-season zones increases the probability of freezing injury and increases the need for an improved understanding of physiological responses to chilling and freezing temperatures. Abscisic acid (ABA) has been shown to increase during cold acclimation (CA) and play a role in dehydration tolerance. This study investigated changes in ABA metabolism and dehydrin expression during CA and their association with freezing tolerance in four bermudagrass cultivars. Two cold-tolerant (‘Patriot’ and ‘Riviera’) and two relatively cold-sensitive (‘Tifway’ and ‘Princess’) cultivars were either subjected to CA at 8 °C day/4 °C night with a light intensity of 250 μmol·m−2·s−1 over a 10-h photoperiod for 21 days or maintained at 28 °C day/24 °C night over a 12-h photoperiod. In a separate study, exogenous ABA at 0, 50, 100, and 150 μm was applied to ‘Patriot’ bermudagrass without CA. ABA content in leaf and stolon tissues increased substantially during the first week of CA and remained relatively stable thereafter. ‘Patriot’ and ‘Riviera’ had greater ABA content and less stolon electrolyte leakage (EL) relative to ‘Tifway’ and ‘Princess’. Expression of a 25 kDa dehydrin protein increased during CA in all four cultivars. A significant correlation was found between ABA content and freezing tolerance. Exogenously applying ABA to ‘Patriot’ at 50, 100, and 150 μm significantly increased endogenous ABA content and the 25 kDa dehydrin expression and reduced stolon EL. The results suggest that alteration of ABA metabolism during CA is closely associated with freezing tolerance. Selection and use of cultivars with substantial accumulation of ABA and certain dehydrins during CA or in response to exogenous ABA could improve bermudagrass persistence in transition zone climates.
Evaluation of a Herbicide-resistant Trait Conferred by the Bar Gene Driven by Four Distinct Promoters in Transgenic Blueberry Plants
Authors: Song Guo-Qing , Sink Kenneth C. , Callow Peter W. , Baughan Rebecca , Hancock James F.
Published: January 2019

Four chimeric bialaphos resistance (bar) genes driven by different promoters were evaluated for production of herbicide-resistant ‘Legacy’ blueberry plants (73.4% Vaccinium corymbosum L. and 25% Vaccinium darrowi Camp) through Agrobacterium tumefaciens (Smith & Towns.) Conn.-mediated transformation. When the bars were used as selectable marker genes, different promoters yielded different transformation frequencies. Three chimeric bar genes with the promoter nopaline synthase (nos), cauliflower mosaic virus (CaMV) 35S, or CaMV 34S yielded transgenic plants, whereas a synthetic (Aocs)3AmasPmas promoter did not lead to successful regeneration of transgenic plants. In addition, herbicide resistance in bar-expressing plants was influenced by the promoter strength. Under controlled environmental conditions, 3-month-old plants from six single-copy transgenic events with 35S∷bar or nos∷bar, as well as those nontransgenic plants, were sprayed with herbicide glufosinate ammonium (GS) at five levels (0, 750, 1500, 3000, and 6000 mg·L−1). Evaluations on leaf damage 2 weeks after spraying indicated that all transgenic plants exhibited much higher herbicide resistance than nontransgenic plants. Additionally, the transgenic plants with the 35S∷bar showed a higher herbicide resistance than those with the nos∷bar. After application of 6000 mg·L−1 GS, over 90% of the leaves from plants with the 35S∷bar and 19.5% to 51.5% of the leaves from plants with the nos∷bar showed no symptom of herbicide damage, whereas only 5% of leaves from the nontransgenic had no damage. One-year-old, field-grown plants from four transgenic events with the nos∷bar were evaluated for herbicide resistance after spraying with 750 mg·L−1 GS. Transgenic plants survived with variations in the level of foliar damage; in contrast, all nontransgenic plants died. This study is the first investigation of different promoters for engineering transgenic blueberry plants.
Influence of Root Zone Calcium on Subapical Necrosis in Potato Shoot Cultures: Localization of Injury at the Tissue and Cellular Levels
Authors: Busse James S. , Ozgen Senay , Palta Jiwan P.
Published: January 2019

Shoot tip necrosis has been attributed to calcium deficiency in in vitro cultures, resulting in death of the stem tip, the loss of apical dominance, and axillary branch development. Using an in vitro shoot culture system with Solanum tuberosum L. cv. Dark Red Norland, we studied the development of injury symptoms at the microscopic and tissue levels at a range of media calcium concentrations varying from 6.8 to 3000 μm. Light and electron microscopic studies revealed that the primary injury due to calcium deficiency was the death and collapse of expanding pith cells below the shoot apex. The structure and organization of the shoot apical meristem was the same when plants were cultured on sufficient or suboptimal media calcium concentrations. However, the apical meristem senesced following subapical shoot tissue collapse. Death of the shoot apical meristem was a secondary effect of calcium deficiency, resulting in loss of apical dominance. Studies with 45Ca indicated that calcium was distributed in a gradient along the shoot, with highest concentration at the base and the lowest at the apex. Shoot tip necrosis developed after 20 days of culture on the suboptimal calcium concentration medium. The development of these symptoms and axillary shoot growth was associated with the lack of calcium accumulation in the shoots. Our results provide evidence that a primary injury of calcium deficiency is localized in the expanding pith cells below the shoot apical meristem and this injury results in the collapse of subapical cells. Death of the shoot apical meristem is a secondary injury resulting from calcium deficiency.
Alleviation of Copper Toxicity in Arabidopsis thaliana by Silicon Addition to Hydroponic Solutions
Authors: Li Jie , Leisner Scott M. , Frantz Jonathan
Published: January 2019

Copper (Cu) is an essential micronutrient for plants and is the a.i. in pesticides for some pathogens and algae. Elevated doses of Cu can cause toxicity in plants. While silicon (Si) is reported to alleviate the toxicity of some heavy metals, its role in reducing the symptoms induced by excess Cu is unclear. Therefore, the role of Si in plant response to Cu stress was investigated in arabidopsis [Arabidopsis thaliana (L.) Heyn.]. Based on plant symptoms (a reduction of leaf chlorosis as well as increased shoot and root biomass) and a reduction of phenylalanine ammonia lyase [PAL (EC 4.3.1.5), a stress-induced enzyme] activity in the shoot, Si was found to alleviate copper stress. Real-time reverse transcriptase-polymerase chain reaction analyses indicated that the RNA levels of two arabidopsis copper transporter genes, copper transporter 1 (COPT1) and heavy metal ATPase subunit 5 (HMA5) were induced by high levels of Cu, but were significantly decreased when Si levels were also elevated. Taken together, our findings indicate that Si addition can improve the resistance of arabidopsis to Cu stress, and this improvement operates on multiple levels, ranging from physiological changes to alterations of gene expression.
Applying Freezing Test to Quantify Cold Acclimation in Medicago truncatula
Authors: Thapa Babita , Arora Rajeev , Knapp Allen D. , Brummer E. Charles
Published: January 2019

Understanding cold acclimation (CA) is important for concurrently improving autumn yield and winter survival in alfalfa (Medicago sativa L.). Medicago truncatula Gaertn., an annual relative of alfalfa, could be used to determine genetic bases of CA, if the ability and conditions required for its CA are determined. The major objective of this study was to develop a laboratory screening procedure to quantify CA in M. truncatula. Two genotypes, Jemalong-6 and W6 5018, were grown in nonacclimation (NA) and three CA regimes (CA1, CA2, and CA3). CA was quantified by measuring freezing tolerance [LT50 (the freeze temperature at which 50% injury occurred)], as estimated by ion leakage (IL) from leaf tissues. The percentage of injury and LT50 were derived from freeze injury data. Cold-acclimated plants had reduced stem length, number of leaves, stem dry weight, leaf dry weight, and root dry weight compared with control. Root-to-shoot ratio was higher in cold-acclimated than in control plants. These results indicate the clear initiation of acclimation response in cold-acclimated plants. Average LT50 temperatures were −3, −8, −7.8, and ≥ −12.5 °C in NA, CA1, CA2, and CA3 regimes, respectively. While 80% injury was induced by −7 °C in NA plants, −20 °C only induced an average of 52% injury in CA3 plants. While the percentage of injury was lower in Jemalong-6 than in W6 5018 for all CA regimes, CA3 regime was most effective in distinguishing CA ability of the two genotypes. Our results demonstrated the capability of M. truncatula to cold acclimate under the controlled CA regimes and the possible use of IL as a rapid laboratory method to quantify CA.
Microsatellite Loci Transferability in Chestnut
Authors: Wang Ying , Kang Ming , Huang Hongwen
Published: January 2019

Cross-species amplification of 55 microsatellite loci developed in european chestnut (Castanea sativa Mill.) and japanese chestnut (C. crenata Sieb & Zucc.) was tested in three chestnut species from China [C. mollissima Blume, C. seguinii Dode, and C. henryi (Skan.) Rehder & Wilson]. Among all the tested loci, 47 (85.5%), 47 (85.5%), and 44 (80%) were successfully amplified in each of the three Chinese species, respectively. All microsatellite loci tested from C. crenata successfully amplified in the Chinese species, while only 80.5%, 80.5%, and 73.2% of the loci originating from C. sativa amplified in the three Chinese species. The level of polymorphism and mean number of alleles was 58.2% and 4.12 for C. mollissima, 60% and 4.64 for C. seguinii, and 60% and 4.76 for C. henryi, with mean observed heterozygosity ranging from 0.440 to 0.549 and mean expected heterozygosity ranging from 0.506 to 0.615. Transferability of Castanea Mill. microsatellites provides a powerful tool for chestnut breeding programs and conservation genetic studies of Castanea species.
Suitability of EST-PCR Markers Developed in Highbush Blueberry for Genetic Fingerprinting and Relationship Studies in Lowbush Blueberry and Related Species
Authors: Bell Daniel J. , Rowland Lisa J. , Polashock James J. , Drummond Frank A.
Published: January 2019

Little is known of the genetic structure and variability of wild fields, or of the dramatic differences in yield among clones (genetic individuals), of lowbush blueberry (Vaccinium angustifolium Ait.), Maine's most economically important fruit crop. Express sequence tag-polymerase chain reaction (EST-PCR) markers that were originally developed for genetic mapping purposes in highbush blueberry (Vaccinium corymbosum L.) are shown here to be valuable for genetic fingerprinting and relationship studies in the related species, V. angustifolium. As part of an interspecific genetic relationship study, 14 genotypes, including at least two specimens of each of four closely related Vaccinium L. species (V. pallidum Ait., V. corymbosum, V. boreale Hall & Aald., and V. myrtilloides Michx.) and the only four pedigreed cultivars of V. angustifolium, grouped out as expected in a genetic similarity dendrogram (matrix “r” correlation = 0.91). This work is ultimately aimed at using these markers in exploring how genetic relationship affects yield among proximal and distant breeding individuals via controlled field hand crosses. To help address this issue, a separate group of six individuals of V. angustifolium from two managed fields were also genotyped using the EST-PCR markers. The markers were very effective at intraspecific discrimination of individuals within the same field.
Effect of Dropping on Le-ACS2 Accumulation Around the Mechanically Stressed Site of the Tomato Fruit
Authors: Usuda Hiroyuki , Nei Daisuke , Ito Yasuhiro , Nakamura Nobutaka , Ishikawa Yutaka , Umehara Hitomi , Roy Poritosh , Okadome Hiroshi , Thammawong Manasikan , Shiina Takeo , Kitagawa Mamiko , Satake Takaaki
Published: January 2019

Ethylene production and the accumulation of the 1-aminocyclopropane-1-carboxylic acid synthase (ACS; EC 4.4.1.14) gene were determined in tomato (Solanum lycopersicum L.) fruit that were dropped from a height of 5 cm. Dropped fruit had higher ethylene production than nondropped controls, and this lasted for at least 10 h. Maximum accumulation of Le-ACS2, one of the members of the Le-ACS multigene family, was achieved 5 h after dropping, and changes in accumulation tracked closely with ethylene production. In comparison with control fruit, substantial accumulation of Le-ACS1A, Le-ACS4, or Le-ACS6 in dropped fruit was not observed. These results indicated that the increased ethylene production following fruit dropping was most likely regulated by Le-ACS2 transcripts. The transfer of dropping stimuli from directly stressed tissues was investigated by measuring Le-ACS2 accumulation at various positions on the dropped fruit. Le-ACS2 was mainly induced in the fruit pericarp, and there was low accumulation in the fruit interior. The Le-ACS2 accumulation linearly decreased with increasing distance along the pericarp from the stressed site. This implied that accumulation of Le-ACS2 was dependent on stress levels, while most ethylene that was derived from dropping was produced at the stressed site. Using levels of Le-ACS2 accumulation, the ethylene production of tomato fruit at mechanically impacted sites was estimated to be about 50 times higher than that of nondropped controls.
Aminoethoxyvinylglycine Inhibits Fruit Abscission Induced by Naphthaleneacetic Acid and Associated Relationships with Expression of Genes for Ethylene Biosynthesis, Perception, and Cell Wall Degradation in ‘Delicious’ Apples
Authors: Zhu Hong , Beers Eric P. , Yuan Rongcai
Published: January 2019

Effects of naphthaleneacetic acid (NAA) and aminoethoxyvinylglycine (AVG) on young fruit abscission, leaf and fruit ethylene production, and expression of genes related to ethylene biosynthesis and cell wall degradation were examined in ‘Delicious’ apples (Malus ×domestica Borkh.). NAA at 15 mg·L−1 increased fruit abscission and ethylene production of leaves and fruit when applied at the 11-mm stage of fruit development, whereas AVG, an inhibitor of ethylene biosynthesis, at 250 mg·L−1 reduced NAA-induced fruit abscission and ethylene production of leaves and fruit. NAA also increased expression of 1-aminocyclopropane-1-carboxylate (ACC) synthase genes (MdACS5A and MdACS5B), ACC oxidase gene (MdACO1), and ethylene receptor genes (MdETR1a, MdETR1b, MdETR2, MdERS1, and MdERS2) in fruit cortex and fruit abscission zones. However, AVG reduced NAA-induced expression of these genes except for MdERS2 in fruit abscission zones. NAA increased expression of the polygalacturonase gene MdPG2 in fruit abscission zones but not in fruit cortex, whereas AVG reduced NAA-enhanced expression of MdPG2 in fruit abscission zones. The expression of β-1,4-glucanase gene MdCel1 in fruit abscission zones was decreased by NAA but was unaffected by AVG. Our results suggest that ethylene biosynthesis, ethylene perception, and the MdPG2 gene are involved in young fruit abscission caused by NAA.