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N F Weeden

Publications and source records attributed to N F Weeden.

At least 19 recordsLinked to original sources
PubMed2001

RAPD-based assessment of genetic similarity and distance between Lupinus species in section Albus.

It was earlier suggested that the lupine taxa identified as Lupinus graecus Boissier et Spruner, L. jugoslavicus Kazim. et Now., and L. vavilovi Majss. et Atab. should be considered one species, L. albus, with two botanical varieties: var. albus (bitter cultivated form) and var. graecus (wild ancestor). We investigated this possibility by examining the genetic distance between L. albus, L. termis and L. vavilovi with RAPD markers. The genetic distances between taxa were found to be very small (<0.1), similar to results for other conspecific taxa. In addition, only three of 146 amplified fragments examined were unique to a specific taxon (L. vavilovi). We conclude that the three taxa studied belong to one species and can be divided into two varieties, as suggested earlier.

Journal Article↗
PubMed2000

A gene controlling sex in grapevines placed on a molecular marker-based genetic map.

Genetic maps of Vitis (2n = 38) have been constructed from an interspecific hybrid population of 58 seedlings of the cross 'Horizon' ('Seyval' x 'Schuyler') x Illinois 547-1 (V. cinerea B9 x V. rupestris B38). The maps were initially constructed based on 277 RAPD (random amplified polymorphic DNA) markers using a double-pseudotestcross strategy. Subsequently, 25 microsatellites, 4 CAPS (cleaved amplified polymorphic sequence), and 12 AFLP (amplified fragment length polymorphism) markers were added to the maps. Another 120 markers, mostly those segregating 3:1, were also assigned but not positioned on the linkage groups in the two maps. The 'Horizon' map consisted of 153 markers covering 1199 cM, with an average map distance of 7.6 cM between markers. The Illinois 547-1 map had 179 markers covering 1470 cM, with an average map distance of 8.1 cM. There were 20 linkage groups in each map, one more than the basic number of chromosomes in grapes. Ten linkage groups in each map were identified as homologous using 16 microsatellite and 2 CAPS markers polymorphic in both parents. A single locus controlling sex in grapes mapped close to a microsatellite marker. These maps provide enough coverage of the genome for QTL (quantitative trait loci) analysis and as a starting point for positional gene cloning in grapes.

Chromosome Mapping↗
PubMed1995

Molecular evolution of duplicate copies of genes encoding cytosolic glutamine synthetase in Pisum sativum.

Here, we describe two nearly identical expressed genes for cytosolic glutamine synthetase (GS3A and GS3B) in Pisum sativum L. RFLP mapping data indicates that the GS3A and GS3B genes are separate loci located on different chromosomes. DNA sequencing of the GS3A and GS3B genes revealed that the coding regions are 99% identical with only simple nucleotide substitutions resulting in three amino acid differences. Surprisingly, the non-coding regions (5' non-coding leader, the 11 introns, and 3' non-coding tail) all showed a high degree of identity (96%). In these non-coding regions, 25% of the observed differences between the GS3A and GS3B genes were deletions or duplications. The single difference in the 3' non-coding regions of the GS3A and GS3B genes was a 25 bp duplication of an AU-rich element in the GS3B gene. As the GS3B mRNA accumulates to lower levels than the GS3A gene, we tested whether this sequence which resembles an mRNA instability determinant functioned as such in the context of the GS mRNA. Using the GS3B 3' tail as part of a chimeric gene in transgenic plants, we showed that this AU-rich sequence has little effect on transgene mRNA levels. To determine whether the GS3A/GS3B genes represent a recent duplication, we examined GS3-like genes in genomic DNA of ancient relatives of P. sativum. We observed that several members of the Viceae each contain two genomic DNA fragments homologous to the GS3B gene, suggesting that this is an ancient duplication event. Gene conversion has been invoked as a possible mechanism for maintaining the high level of nucleotide similarity found between GS3A and GS3B genes. Possible evolutionary reasons for the maintenance of these 'twin' GS genes in pea, and the general duplication of genes for cytosolic GS in all plant species are discussed.

Base Sequence↗
PubMed1995

A molecular marker based linkage map of Vitis.

Genetic linkage maps of Vitis (2n = 38) have been constructed from a single interspecific hybrid grape population (60 seedlings) of 'Cayuga White' X 'Aurore'. The maps were primarily based on 422 RAPD markers but also included 16 RFLP and isozyme markers. These maps had an average distance of 6.1 cM between markers and were developed using a double-pseudotestcross strategy. The 'Cayuga White' map had 214 markers covering 1196 cM and that of 'Aurore' spanned over 1477 cM with 225 markers. The 'Cayuga White' map consisted of 20 linkage groups, whereas 22 linkage groups comprised the 'Aurore' map. The number of groups reduced to 19, as in some instances two or more groups from one parent showed homology with a single group from the other parent on the basis of markers heterozygous in both parents. Each linkage group ranged in size from 14 to 135 cM in 'Aurore' and from 14 to 124 cM in 'Cayuga White'. These maps provide enough coverage of the genome to allow quantitative trait locus analysis and map-based gene cloning.

Base Sequence↗
PubMed1994

The reduced stability of a plant alcohol dehydrogenase is due to the substitution of serine for a highly conserved phenylalanine residue.

The zinc-binding long-chain alcohol dehydrogenases from plants and animals exhibit a considerable level of amino acid sequence conservation. While the functional importance of many of the conserved residues is known, the role of others has not yet been determined. We have identified a naturally occurring Adh-1 allele in the legume Phaseolus acutifolius with several unusual characteristics. Individuals homozygous for this allele, Adh-1 CN, possess a single isozyme starch gel electrophoretic pattern suggestive of a null allele, and exhibit ADH enzyme activity levels ca. 60% lower than the standard wild-type Adh-1F line. Interestingly, analysis of Adh-1CN homozygotes on an alternative gel system indicates that Adh-1CN does encode a polypeptide capable of forming functional homo- and heterodimers. However, the levels of ADH activity displayed by these isozymes are far lower than those observed for the corresponding wild type ADH-1F isozymes. Dialysis experiments indicate that isozymes containing the ADH-1CN polypeptide are inactivated by slightly acidic conditions, which may explain the apparent null phenotype on starch gels. Elevated temperatures cause a similar loss of enzyme activity. The deduced amino acid sequences of ADH-1CN and ADH-1F were obtained from their corresponding cDNA clones, and the only significant difference detected between the two is a single amino acid replacement substitution. Residue 144 is occupied by phenylalanine in the ADH-1F polypeptide, whereas serine occupies this position in the ADH-1CN polypeptide. The proximity of residue 144 to the catalytic zinc in the substrate-binding pocket, coupled with the fact that it is integral to a defined hydrophobic core of the ADH polypeptide, may explain the observed disruptive effect that the serine substitution has on both the activity and stability of the ADH-1CN polypeptide. It also provides an explanation for the maintenance of phenylalanine or the structurally similar tyrosine at this residue in Zn-binding long-chain ADHs.

Alcohol Dehydrogenase↗
PubMed1991

Transfer of rpl22 to the nucleus greatly preceded its loss from the chloroplast and involved the gain of an intron.

Most chloroplast and mitochondrial proteins are encoded by nuclear genes that once resided in the organellar genomes. Transfer of most of these genes appears to have occurred soon after the endosymbiotic origin of organelles, and so little is known about the process. Our efforts to understand how chloroplast genes are functionally transferred to the nuclear genome have led us to discover the most recent evolutionary gene transfer yet described. The gene rpl22, encoding chloroplast ribosomal protein CL22, is present in the chloroplast genome of all plants examined except legumes, while a functional copy of rpl22 is located in the nucleus of the legume pea. The nuclear rpl22 gene has acquired two additional domains relative to its chloroplast ancestor: an exon encoding a putative N-terminal transit peptide, followed by an intron which separates this first exon from the evolutionarily conserved, chloroplast-derived portion of the gene. This gene structure suggests that the transferred region may have acquired its transit peptide by a form of exon shuffling. Surprisingly, phylogenetic analysis shows that rpl22 was transferred to the nucleus in a common ancestor of all flowering plants, at least 100 million years preceding its loss from the legume chloroplast lineage.

Amino Acid Sequence↗
PubMed1990

Pleiotropic Effects of brz: A Mutation in Pisum sativum (L.) cv ;Sparkle' Conditioning Decreased Nodulation and Increased Iron Uptake and Leaf Necrosis.

Treatment of Pisum sativum (L.) cv ;Sparkle' with ethylmethane sulfonic acid produced a stable mutant, E107, which forms few nodules. The mutant allele exhibits other pleiotropic properties including bronze necrotic spots on the leaflets and high accumulation of iron in the shoot. The mutant phenotype is under monogenic recessive control. The gene, designated brz (bronze), is nonallelic with two other genes conditioning necrotic spots on leaves of other mutants of P. sativum. The brz allele was located on chromosome 4 by linkage with wax production controlled by alleles at the was locus.

Journal Article↗
PubMed1990

sym 13-A Gene Conditioning Ineffective Nodulation in Pisum sativum.

Treatment of Pisum sativum (L.) cv. ;Sparkle' with ethyl methanesulfonic acid (EMS) produced a stable mutant, E135F, which forms small, white, ineffective nodules. These nodules exhibit histological zonation typical of an indeterminant nodule, e.g. meristematic, early symbiotic, late symbiotic, and senescent zones. Compared with the nitrogen fixing nodules of the parent, the zones are smaller and the nodules senesce prematurely. Bacteroids in E135F are less elongated and less differentiated than those in ;Sparkle.' The E135F mutant forms ineffective nodules when inoculated with nine different effective strains of Rhizobium leguminosarum and also when grown in a soil containing effective strains. The ineffective phenotype of E135F is under monogenic recessive control; the gene is designated sym 13. sym 13 was located on chromosome 2 by linkage with genes for shikimic dehydrogenase and esterase-2. The original selection E135F carried another mutation in heterozygous form at a separate locus, yielding some homozygous recessive nonnodulating progeny, E135N, in later generations. This indicates that EMS treatments may cause mutations at more than one sym gene. The gene conditioning non-nodulation in E135N was designated sym 14. It mapped to a locus on a different part of chromosome 2 by linkage to the gene for fumarase. The data demonstrate that sym genes are not necessarily closely linked.

Journal Article↗
PubMed1986

Enzymatic control of anthocyanin expression in the flowers of pea (Pisum sativum) mutants.

Using enzymological and immunological methods we have investigated the relationship between chalcone synthase and the A locus, a major gene involved in the control of anthocyanin expression in pea (Pisum sativum L.) flowers. Pea plants containing the dominant allele A usually synthesize anthocyanins in the petal tissue, whereas plants homozygous for the a allele do not produce anthocyanins. We sought to determine whether or not the A locus also controlled the presence or absence of chalcone synthase, the first enzyme of the flavonoid pathway in the flowers of three genetic lines (A, purple-violet flowers; A,am, white flowers with sometimes pink edges; and a, white flowers). Chalcone synthase was found to be present in all three genetic lines by enzyme activity measurement, indirect enzyme-linked immunosorbent assay (ELISA), and Western blotting. Spectroscopic investigations showed that only the genetic lines A and A,am contained anthocyanins and flavonol glycosides, respectively, in the flowers; line a accumulated p-coumaric acid or its derivatives. These data suggest that the A locus in Pisum is not the structural gene for chalcone synthase and it does not appear to regulate the expression of this enzyme.

Acyltransferases↗
PubMed1986

Isolation and characterization of buckwheat (Fagopyrum esculentum M.) chalcone synthase and its polyclonal antibodies.

Chalcone synthase was isolated from illuminated buckwheat (Fagopyrum esculentum M.) hypocotyls and purified to electrophoretic homogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis using (NH)4SO4 fractionation, gel filtration on AcA 44, ion exchange chromatography on DEAE-Bio-Gel, and HPLC on hydroxylapatite. The properties of the enzyme were pH optimum, 8.0; Mr approximately 83,000 +/- 1000; Mr subunit, approximately 41,500 +/- 500; isoelectric point, pH 5.2; Km, 1 X 10(-6)M for malonyl-CoA, and 0.6 X 10(-6) M for p-coumaryl-CoA. Buckwheat chalcone synthase used p-coumaryl-CoA as substrate and also utilized caffeyl-CoA and ferulyl-CoA at 20 and 80%, respectively, of the rate of p-coumaryl-CoA in the chalcone synthase reaction. Antibodies against the buckwheat chalcone synthase were developed in a New Zealand white rabbit and characterized for specificity by enzyme-linked immunosorbent assay, Ouchterlony double immunodiffusion, and Western blotting.

Acyltransferases↗
PubMed1985

Inheritance, organization, and mapping of rbcS and cab multigene families in pea.

DNA restriction endonuclease fragment patterns corresponding to both the rbcS and cab multigene families of pea are each shown to segregate as single Mendelian units in the F(2) progeny of two separate crosses. All of the observed variation in each of the multigene families is thus organized on the chromosome in a tightly linked complex. Linkage relationships between both multigene families and an array of morphological and isozyme markers establish the location of the rbcS and cab gene clusters on pea chromosomes 5 and 2, respectively. Our results, which indicate a high level of DNA restriction fragment length polymorphism in pea, suggest sufficient variation to permit the construction of a highly detailed linkage map.

Journal Article↗
PubMed1983

Leaf Cytosolic Fructose-1,6-bisphosphatase : A Potential Target Site in Low Temperature Stress.

Leaf cytosolic fructose-1,6-bisphosphatase (FBPase), partially purified from both spinach (Spinacia oleracea, var Hipack) and peas (Pisum sativum, var Progress No. 9), is reversibly inactivated by exposure to low temperature. Thus, even though assays were conducted at 22 degrees C, samples incubated at 0 to 12 degrees C had greatly reduced activity relative to controls maintained at 22 degrees C. Following incubation at 22 degrees C prior to assay, the inactivated samples regained their initial activity. Chloroplast FBPase, by contrast, was unaffected by low temperature treatment. This feature as well as lack of a response of cytosolic FBPase to thioredoxins f or c(f) and to chloroplast FBPase antibody indicate that the FBPase isozymes of leaves are different proteins.

Journal Article↗
PubMed1982

A special fructose bisphosphate functions as a cytoplasmic regulatory metabolite in green leaves.

Fructose 2,6-bisphosphate (Fru-2,6-P(2)), a regulatory metabolite discovered in animal cells and recently reported to occur in etiolated seedlings, was found to be present in the cytoplasmic fraction of leaves of spinach and peas (typical C(3) plants, in which a three-carbon carboxylic acid is a major early photosynthetic product). At concentrations approximating those calculated to occur physiologically, Fru-2,6-P(2) modulated two enzymes of the leaf cytoplasm: (i) Fructose-1,6-bisphosphatase (EC 3.1.3.11), a key enzyme of sugar synthesis, was competitively inhibited by Fru-2,6-P(2), and (ii) pyrophosphate-linked phosphofructokinase (inorganic pyrophosphate-D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.90), a cytoplasmic enzyme that now seems important in glycolysis of C(3) plants, was activated by Fru-2,6-P(2). There was no indication of a role for Fru-2,6-P(2) in photosynthesis of either chloroplasts or oxygenic prokaryotes. The results suggest that Fru-2,6-P(2) functions in the regulation of glycolysis and gluconeogenesis (carbohydrate synthesis) in the cytoplasm of leaves of C(3) plants.

Journal Article↗
PubMed1982

Immunological similarity between a cyanobacterial enzyme and a nuclear DNA-encoded plastid-specific isozyme from spinach.

The immunochemical properties of the plastid and cytosolic isozymes of phosphoglucose isomerase (glucosephosphate isomerase; D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) in spinach (Spinacia oleracea) and the single phosphoglucose isomerase enzyme from the cyanobacterium Synechococcus sp. were compared by an application of the enzyme-linked immunosorbent assay. Utilizing antibodies made in rabbits against subunits of purified plastid and cytosolic phosphoglucose isomerase isozymes from spinach, we demonstrate that the plastid isozyme is immunochemically more similar to the cyanobacterial enzyme than to the spinach cytosolic counterpart. The antiserum to plastid phosphoglucose isomerase crossreacted strongly with plastid phosphoglucose isomerases from other flowering plants. The antiserum to cytosolic phosphoglucose isomerase crossreacted with other plant cytosolic phosphoglucose isomerase isozymes. The results are consistent with the hypothesis [Weeden, N. F. (1981) J. Mol. Evol. 17, 133-139] that the nuclear gene specifying plastid phosphoglucose isomerase was derived from a prokaryote after the incorporation of a plastid-like symbiont into the ancestral plant cell.

Journal Article↗
PubMed1982

Dissociation, reassociation, and purification of plastid and cytosolic phosphoglucose isomerase isozymes.

The plastid and cytosolic isozymes of the dimeric enzyme phosphoglucose isomerase (EC 5.3.1.9) from spinach (Spinacia oleracea) and cauliflower (Brassica oleracea) were purified to apparent homogeneity. The isozymes from sunflower (Helianthus annuus) and Clarkia xantiana were partially purified. When subunits from two electrophoretically distinguishable cytosolic isozymes, either from the same or from different species, were dissociated and allowed to reassociate in each other's presence, an active hybrid enzyme, consisting of one subunit of each type, was formed in addition to the two original homodimers. Active hybrid enzymes were also formed by dissociation and reassociation of plastid isozymes. Hybrid molecules were not produced between the plastid and cytosolic subunits, suggesting that they are not able to bind with each other. Additional differences between the plastid and cytosolic isozymes are described.

Journal Article↗