110 research outputs found
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Partial purification and characterization of a zeatin Cis-trans isomerase from Phaseolus vulgaris L.
Conversion of exogenous cis-zeatin to trans-zeatin in immature seeds of
Phaseolus vulgaris L. led to the isolation of a cis-trans isomerase from the endosperm.
The enzyme was purified over 2000-fold by chromatography on a series of FPLC
(anion exchange, gel filtration, and hydrophobic interaction) and Concanavalin A
columns. Non-enzymatic isomerization occurred under standard assay conditions but the
presence of the enzyme enhanced conversion significantly. The enzymatic reaction
favors conversion from the cis to the trans form and requires flavin, blue light, and
DTT. Optimal conditions for isomerization were identified using a Phenyl Superosepurified
enzyme extract. Concentrations of 0.1-0.316 mM FAD and 0.5 mM DTT
resulted in high conversion. The pH optimum for the reaction was 7.5. Although the
isomerase was heat stable, a temperature of 35°C was chosen for the assay reaction in
order to minimize non-enzymatic thermal isomerization. Retention on the Concanavalin
A column as well as shifting in mobility of all visible protein bands on SDS-PAGE
following N-glycosidase-F treatment indicated that the enzyme is a glycoprotein. The
enzyme was stable for at least 8 weeks when stored at -80°C. The isomerase is capable
of converting cis-zeatin riboside and trans-zeatin riboside. Changing the isoprenoid side
chain location from Nⶠin zeatin to the 9-position of the adenine ring in 9-(4-hydroxy-3-
methylbut-2-enyl)adenine also resulted in isomerization. The occurrence of cis-trans
isomerization suggests that cis-zeatin and cis-zeatin riboside formed by tRNA
degradation could be precursors of biologically active cytokinins
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Propagation of filbert (Corylus avellana L.) and Douglas-fir (Pseudotsuga menziesii Mirb. Franco) using Agrobacterium rhizogenes
A High-Density Linkage Map of the Ancestral Diploid Strawberry, Fragaria iinumae, Constructed with Single Nucleotide Polymorphism Markers from the IStraw90 Array and Genotyping by Sequencing
Fragaria iinumae Makino is recognized as an ancestor of the octoploid strawberry species, which includes the cultivated strawberry, Fragaria Ăananassa Duchesne ex Rozier. Here we report the construction of the first high-density linkage map for F. iinumae. The F. iinumae linkage map (Fii map) is based on two high-throughput techniques of single nucleotide polymorphism (SNP) genotyping: the IStraw90 Array (hereafter âArrayâ), and genotyping by sequencing (GBS). The F2 generation mapping population was derived by selfing F. iinumae hybrid F1D, the product of a cross between two divergent F. iinumae accessions collected from Hokkaido, Japan. The Fii map consists of seven linkage groups (LGs) and has an overall length of 451.7 cM as defined by 496 loci populated by 4173 markers: 3280 from the Array and 893 from GBS. Comparisons with two versions of the Fragaria vesca ssp. vesca L. âHawaii 4â pseudo-chromosome (PC) assemblies reveal substantial conservation of synteny and colinearity, yet identified differences that point to possible genomic divergences between F. iinumae and F. vesca, and/or to F. vesca genomic assembly errors. The Fii map provides a basis for anchoring a F. iinumae genome assembly as a prerequisite for constructing a second diploid reference genome for Fragaria
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Nuclear and chloroplast microsatellite markers to assess genetic diversity and evolution in hazelnut species, hybrids and cultivars
The US Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository in Corvallis, Oregon, preserves more than 800 accessions of hazelnut (Corylus), including C. avellana cultivars and representatives of 10 other recognized shrub and tree species. Characterization and study of genetic diversity in this collection require cross-transferable markers, such as trinucleotide microsatellite or simple sequence repeat (SSR) markers and universal chloroplast SSR markers. We developed new SSR markers and evaluated 114 Corylus accessions representing 11 species and 44 interspecific hybrids. Eight of 23 SSRs generated easy-to-score alleles in all species and seven were highly polymorphic. For those seven, the average heterozygosity was moderate at 0.49, and mean allele number, genetic diversity and polymorphism information index were high at 11.71, 0.79 and 0.76, respectively. The three most polymorphic SSRs were CaC-C008, CaC-C040 and CaC-C118. Neighbor-joining (NJ) clustering and structure analysis agreed with classical taxonomic analysis and supported inclusion of C. maxima within the large polymorphic species, C. avellana. Analysis also indicated that C. californica is a distinct species rather than a botanical variety of C. cornuta. Six universal cpSSRs were polymorphic in Corylus and generated 21 distinct chlorotypes with an average of 3 alleles per locus. Diversity at these cpSSRs was high and ranged from 0.33 to 0.64, with an average of 0.54. Incongruence in NJ topologies between the nuclear and chloroplast markers could be attributed to chloroplast capture related to hybridization during the ancestral diversification of the genus, or to homoplasy. The phylogeographical relationships among the 21 chlorotypes in the 11 Corylus species support Asia as a refugium where several hazelnut lineages survived during glaciation and from which they continued to evolve after dispersal from Asia through the Mediterranean to Europe, and across the Atlantic and/or the Bering land bridge to North America.Keywords: Simple sequence repeat (SSR) markers, Filbert, Universal chloroplast SSRs, CorylusKeywords: Simple sequence repeat (SSR) markers, Filbert, Universal chloroplast SSRs, Corylu
Genetic stability of cryopreserved shoot tips of Rubus germplasm
Abstract Questions often arise concerning the genetic stability of plant materials stored in liquid nitrogen for long time periods. This study examined the genetic stability of cryopreserved shoot tips of Rubus germplasm that were stored in liquid nitrogen for more than 12 yr, then rewarmed and regrown. We analyzed the genetic stability of Rubus grabowskii, two blackberry cultivars ("Hillemeyer" and 'Silvan'), and one raspberry cultivar ("Mandarin") as in vitro shoots and as field-grown plants. No morphological differences were observed in greenhouse-grown cryopreserved plants when compared to the control mother plants. In the field, cryopreserved plants appeared similar but were more vigorous than mother plants, with larger leaves, fruit, and seeds. Single sequence repeats (SSR) and amplified fragment length polymorphism (AFLP) analyses were performed on shoots immediately after recovery from cryopreservation and on shoots subcultured for 7 mo before analysis. Ten SSR primers developed from "Marion" and "Meeker" microsatellite-enriched libraries amplified one to 15 alleles per locus, with an average of seven alleles and a total of 70 alleles in the four genotypes tested. No SSR polymorphisms were observed between cryopreserved shoots and the corresponding mother plants regardless of subculture. Although no polymorphisms were detected in shoots analyzed immediately after recovery from cryopreservation, AFLP polymorphisms were detected in three of the four Rubus genotypes after they were subcultured for 7 mo. Field-grown plants from the polymorphic shoot tips of R. grabowskii and 'Silvan' displayed the same AFLP fingerprints as their corresponding mother plants. Only longcultured in vitro shoot tips displayed polymorphisms in vitro, and they were no longer detected when the plants were grown ex vitro. The transitory nature of these polymorphisms should be carefully considered when monitoring for genetic stability
Crop wild relatives as germplasm resource for cultivar improvement in mint (Mentha L.)
Mentha is a strongly scented herb of the Lamiaceae (formerly Labiatae) and includes about 30 species and hybrid species that are distributed or introduced throughout the globe. These fragrant plants have been selected throughout millennia for use by humans as herbs, spices, and pharmaceutical needs. The distilling of essential oils from mint began in Japan and England but has become a significant industrial product for the US, China, India, and other countries. The US Department of Agriculture (USDA), Agricultural Research Service, National Clonal Germplasm Repository (NCGR) maintains a mint genebank in Corvallis, Oregon. This facility preserves and distributes about 450 clones representing 34 taxa, hybrid species, advanced breeder selections, and F1 hybrids. Mint crop wild relatives are included in this unique resource. The majority of mint accessions and hybrids in this collection were initially donated in the 1970s by the A.M. Todd Company, located in Kalamazoo, Michigan. Other representatives of diverse mint taxa and crop wild relatives have since been obtained from collaborators in Australia, New Zealand, Europe, and Vietnam. These mints have been evaluated for cytology, oil components, verticillium wilt resistance, and key morphological characters. Pressed voucher specimens have been prepared for morphological identity verification. An initial set of microsatellite markers has been developed to determine clonal identity and assess genetic diversity. Plant breeders at private and public institutions are using molecular analysis to determine identity and diversity of the USDA mint collection. Evaluation and characterization includes essential oil content, disease resistance, male sterility, and other traits for potential breeding use. These accessions can be a source for parental genes for enhancement efforts to produce hybrids, or for breeding new cultivars for agricultural production. Propagules of Mentha are available for distribution to international researchers as stem cuttings, rhizome cuttings, or seed, which can be requested through the GRIN-Global database of the US National Plant Germplasm System, subject to international treaty and quarantine regulations
Mapping a Novel Black Spot Resistance Locus in the Climbing Rose Brite Eyesâą (âRADbriteâ)
Rose black spot, caused by Diplocarpon rosae, is one of the most devastating foliar diseases of cultivated roses (Rosa spp.). The globally distributed pathogen has the potential to cause large economic losses in the outdoor cultivation of roses. Fungicides are the primary method to manage the disease, but are often viewed unfavorably by home gardeners due to potential environmental and health impacts. As such, rose cultivars with genetic resistance to black spot are highly desired. The tetraploid climbing rose Brite EyesTM (âRADbriteâ) is known for its resistance to black spot. To better characterize the resistance present in Brite EyesTM, phenotyping was conducted on a 94 individual F1 population developed by crossing Brite EyesTM to the susceptible tetraploid rose âMorden Blushâ. Brite EyesTM was resistant to all D. rosae races evaluated except for race 12. The progeny were either resistant or susceptible to all races (2, 3, 8, 9, 10, 11, and 13) evaluated. The segregation ratio was 1:1 (Ï2 = 0.3830, P = 0.5360) suggesting resistance is conferred by a single locus. The roses were genotyped with the WagRhSNP 68K Axiom array and the âpolymapRâ package was used to construct a map. A single resistance locus (Rdr4) was identified on the long arm of chromosome 5 homoeolog 4. Three resistance loci have been previously identified (Rdr1, Rdr2, and Rdr3). Both Rdr1 and Rdr2 are located on a chromosome 1 homoeolog. The chromosomal location of Rdr3 is unknown, however, races 3 and 9 are virulent on Rdr3. Rdr4 is either a novel gene or an allele of Rdr3 as it provides resistance to races 3 and 9. Due to its broad resistance, Rdr4 is an excellent gene to introgress into new rose cultivars
Genomics tools available for unravelling mechanisms underlying agronomical traits in strawberry with more to come
In the last few years, high-throughput genomics promised to bridge the gap between plant physiology and plant sciences. In addition, high-throughput genotyping technologies facilitate marker-based selection for better performing genotypes. In strawberry, Fragaria vesca was the first reference sequence obtained in the Rosoideae sub-family. This genome has a high level of synteny with genomes of other species of diploid and polyploid Fragaria, but it also provides a reference for species like Rubus and Rosa for functional genomics. Many tools for genetic, genomic and functional analyses were introduced over the last 10 years and these tools are still evolving. For genotyping, many studies have used simple sequence repeats (SSRs) but whole genome sequencing is now a mature technology and facilitates the development of genotyping chips and other genetic approaches such as genome wide association studies (GWAS). Furthermore, microarray-based technologies have been eclipsed by RNA-seq, the high-throughput sequencing of RNA. These new approaches have led to advances in our understanding of the genetically complex octoploid species, and have revolutionized functional genomics. For all genetic and genomic studies, novel material such as complex crosses such as NILs and EMS have appeared in addition to the classical segregating population. With all these tools, strawberry now emerges as a plant model, not only for studying fruit quality but also for deciphering the mechanisms controlling various aspects of plant biology. Selective examples will be described to illustrate the latest research on strawberry and what is coming from other model species.Peer reviewe
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A roadmap for research in octoploid strawberry
The cultivated strawberry (FragariaâĂâananassa) is an allo-octoploid species, originating nearly 300 years ago from wild progenitors from the Americas. Since that time the strawberry has become the most widely cultivated fruit crop in the world, universally appealing due to its sensory qualities and health benefits. The recent publication of the first high-quality chromosome-scale octoploid strawberry genome (cv. Camarosa) is enabling rapid advances in genetics, stimulating scientific debate and provoking new research questions. In this forward-looking review we propose avenues of research toward new biological insights and applications to agriculture. Among these are the origins of the genome, characterization of genetic variants, and big data approaches to breeding. Key areas of research in molecular biology will include the control of flowering, fruit development, fruit quality, and plantâpathogen interactions. In order to realize this potential as a global community, investments in genome resources must be continually augmented.Peer reviewe
Autopolyploid inheritance and a heterozygous reciprocal translocation shape chromosome genetic behavior in tetraploid blueberry (Vaccinium corymbosum)
Understanding chromosome recombination behavior in polyploidy species is key to advancing genetic discoveries. In blueberry, a tetraploid species, the line of evidences about its genetic behavior still remain poorly understood, owing to the inter-specific, and inter-ploidy admixture of its genome and lack of in depth genome-wide inheritance and comparative structural studies. Here we describe a new high-quality, phased, chromosome-scale genome of a diploid blueberry, clone W85. The genome was integrated with cytogenetics and high-density, genetic maps representing six tetraploid blueberry cultivars, harboring different levels of wild genome admixture, to uncover recombination behavior and structural genome divergence across tetraploid and wild diploid species. Analysis of chromosome inheritance and pairing demonstrated that tetraploid blueberry behaves as an autotetraploid with tetrasomic inheritance. Comparative analysis demonstrated the presence of a reciprocal, heterozygous, translocation spanning one homolog of chr-6 and one of chr-10 in the cultivar Draper. The translocation affects pairing and recombination of chromosomes 6 and 10. Besides the translocation detected in Draper, no other structural genomic divergences were detected across tetraploid cultivars and highly inter-crossable wild diploid species. These findings and resources will facilitate new genetic and comparative genomic studies in Vaccinium and the development of genomic assisted selection strategy for this cro
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