DNA content of Phaseolus coccineus x P. vulgaris suspensors

Summary At the globular stage of embryo development, the level of DNA, as determined from microspectrophotometric analysis of Feulgen-stained squashes, was significantly higher in the interspecific hybrid suspensor than in suspensors from self-pollination of Phaseolus coccineus, the maternal parent. However, at the early-heart and early-cotyledonary stages of development, DNA content of interspecific hybrid suspensors was significantly lower than that of suspensors formed after self-pollination of either P. coccineus or P. vulgaris. The relationship between DNA content and suspensor cell length for P. coccineus and P. vulgaris at all developmental stages and between DNA content and cell area for P. coccineus at the early-cotyledonary stage was altered in hybrid suspensor cells. Nuclei in large cells of interspecific suspensors exhibited uneven distribution of polytene chromosomes and no clear nuclear outline.Paper number 18,470 of the Scientific Journal Series, University of Minnsota Agricultural Experiment Station, St. Paul, MN. This research was funded by the USDA CRGO under grant number USDA-85-CRCR-1-1676     

8-[C]Benzylaminopurine Translocation in Phaseolus vulgaris

[8-¹⁴C]Benzylaminopurine (BA) translocation was studied in whole plants of Phaseolus vulgaris L. under three different light regimes (continuous light, 8-hour light + 16-hour dark, dark). Applications were made to the apex, to a cotyledonary leaf, or to the root system. Results showed that no BA basipetal translocation occurred, however BA is easily absorbed by the root system and is translocated acropetally.     

Chlorophyll mutations induced by gamma radiation in Phaseolus vulgaris L]

In a study of chlorophyll mutants of Phaseolus vulgaris L. through Co60 gamma radiation, five types of mutants, classified as albino, cream, yellow, yellow-green and light green were obtained; all were lethal; their segregation was always proportionally lower than the Mendelian. Gamma radiation-induced mutations in black beans do not depart significantly from those obtained elsewhere in barley and wheat.     

Increase in DNA Content of Primary Leaves of Phaseolus vulgaris upon Decapitation

Changes in DNA content of bean (Phaseolus vulgaris) primaryleaves after decapitation were investigated. When apical budswere removed at 11 d, DNA content per leaf increased by about20% at 15 d and then decreased in parallel with the controls.The RNA and chlorophyll contents, fresh weight, and leaf areaexpressed on a single leaf basis changed in the same manneras the DNA content in response to decapitation. But when bothapical and lateral buds were removed, all these values continuedincreasing during the test period. Thus, growing lateral budsand apical buds have the same effect on the DNA change in primaryleaves as that due to ageing of the leaves. Cell number perleaf was not increased by any treatment, indicating that theobserved increase in the DNA content of primary leaves is ascribableto an increase in DNA per cell. Next, the whole shoots above the nodes of primary leaves wereremoved at various ages. The response of primary leaves to decapitationvaried according to their age. With age, they lost the abilityto increase their fresh weight, area, and chlorophyll contentbut not their DNA and RNA contents in response to decapitation.Decapitation stimulated chloroplast replication only withinthe period in which chloroplasts were replicating in controlleaves, but it induced chloroplast enlargement at any age. Therefore,the increase in DNA content after decapitation may be partiallydue to an increase in the amount of chloroplast DNA. When stems were heat-girdled above the nodes of the primaryleaves, these leaves showed responses similar to but smallerthan those to decapitation. The senescence of primary leavesseems to be controlled by the distribution of substances whichare transported from the roots.     

Cloning and characterization of a Beta vulgaris satellite DNA family

Three members of the BamHI-sequence family of sugar beet (Beta vulgaris) have been cloned in Escherichia coli and compared by sequence analysis. The sequence family shows the typical features of eukaryotic satellite DNA, e.g., organization in tandem arrays and sequence divergence. A typical ladder pattern of a monomer (327 bp) and multiple oligodeoxyribonucleotides have been observed. The BamHI monomer is A + T-rich (69%) and does not show any similarity to other known plant satellite DNAs.     

Aspects of 8-[C]Benzylaminopurine Metabolism in Phaseolus vulgaris

Phaseolus vulgaris L. plants were supplied through the root with [8-¹⁴C]benzylaminopurine ([¹⁴C]BA). Collections of root, apex, and leaves were made 8 and 48 hours after labeling; ethanolic extracts of tissues were purified and subjected to thin layer chromatography on silica gel and/or cellulose powder.     

Properties of satellite DNA from Brassica nigra

The DNA components of B. nigra were preparatively separated by equilibrium ultracentrifugation in a CsCl density gradient, the buoyant density of the main component being 1,696 g . cm-3, that of the satellite component--1,704 g . cm-3. The properties of individual DNA fractions were investigated. Four major components could be observed on the differential melting curve of satellite DNA. Using the reassociation kinetics method it was shown that 30% of satellite DNA are presented as a fast reassociating component with a length of a repeated unit of approximately 2,5 . 10(3) nucleotide pairs. The calculated values of Tm and buoyant density suggest that the m5C content in satellite DNA is lower than that in the main component. During equilibrium ultracentrifugation in the density gradients of actinomycin D--CsCl and Hg2+--Cs2SO4 the satellite DNA is split into 4 major components.     

Endogene Stoffproduktionsrhythmen bei Phaseolus vulgaris

Experimente mit vollausgewachsenen Primär- und Folgeblättern der Buschbohne cv. Saxa unter programmierten Klimabedingungen ergaben bei der Bestimmung der Stoffproduktion mit Hilfe eines Kalorimeters rhythmische Änderungen in dem auf die assimilierende Blattfläche (V_F) bzw. das Trockengewicht bezogenen (V_T) Energiegehalt der produzierten Pflanzenstoffe. Die Trockensubstanzproduktion paßte sich regelmäßig der in der Klimakammer eingestellten Photoperiode an. Am Ende einer Lichtperiode ist der auf die Blattfläche bezogene Kalorienwert V_F stets wesentlich höher als am Ende einer Dunkelperiode; die Pflanze arbeitet also nur im Licht mit positiver Bilanz. Bezieht man den Energiewert jedoch auf das Trockengewicht (V_T), ist es gerade umgekehrt, d. h. in der Dunkelheit werden relativ mehr energiereiche Substanzen angehäuft als im Licht. Im Dauerlicht und Dauerdunkel schwingt der Rhythmus nach. Beim Umschalten auf eine veränderte Photoperiode paßt sich der Rhythmus erst nach Durchlaufen je einer Licht- und Dunkelphase der neuen Behandlung an. Als Auslöser scheint ein einmaliger Hell- und Dunkelwechsel möglich, verschiedene Lichtqualitäten und Photoperioden bleiben ohne Einfluß. Der Zeitgeber für die endogene Rhythmik ist noch unbekannt     

The Ultrastructure of Phaseolus vulgaris Chloroplasts

A comparison of bean chloroplasts after being fixed in potassiumpermanganate, osmium, and formaldehyde coupled with negativestaining shows that the general organization of the chloroplastis similar in all cases. However, the mature chloroplasts ofbean vary considerably in the extent and orientation of theinternal membranes—the grana and the interconnecting membranesbetween the grana. The interconnecting membranes are thin, branching,flexuous structures. This is illustrated by serial sectionsand by cross- and face-view sections of osmium- fixed chloroplastsand the best model, which allows for a considerable flexibilityin the orientation of the grana and also describes the thininterconnecting membranes between the grana, is the grana-fretworksystem proposed by Weier (1961). Furthermore, the comparative studies show that the internalregions of grana are separated from the stroma and that thegrana-fretwork systems appear to be a continuous membrane system.This membrane is single along the frets, end compartments, andgranal margins. It is double in the partitions of the granabut separated by a component, possibly a cementing material,which does not stain. It is suggested that this membrane isstructurally similar in the chloroplasts of higher plants, butthat its overall organization may vary from one plant to another.     

Spectroscopic characterization of Phaseolus vulgaris leucoagglutinin

Phaseolus vulgaris leucoagglutinin is a homotetrameric legume lectin possessing the canonical dimeric structure common to other legume lectins. In order to gain insight into the stability of the protein in an acidic environment, it was characterized by CD and fluorescence studies at pH 2.5. This was then compared with the native protein at physiological pH (7.2). The extinction coefficient of the native protein was calculated to be 3.58x10(4) from its UV absorption spectra. The far- and near-UV CD spectra of the protein at pH 2.5 showed very little difference even though the protein was found to exist as a dimer at pH 2.5. The fluorescence emission maxima of the protein upon excitation at 280 nm were found to shift only from 331 nm at pH 7.2 to 333 nm at pH 2.5. Based on the above observation it was concluded that the protein exhibits extreme pH stability especially in the acidic range. The secondary and tertiary structure of the protein is lost only when it is incubated for two days in 6 M GdnHCl at pH 2.5. At pH 7.2 it could be denatured in 6 M GdnHCl after one week of incubation.     

Cellular double-stranded RNA in Phaseolus vulgaris

Summary High molecular weight double-stranded (ds) RNAs have been detected in apparently virus-free French (common) bean Phaseolus vulgaris cv. Black Turtle Soup (BTS). Several other bean cultivars were free of detectable high molecular weight dsRNAs. The dsRNAs have been partially characterized and have homology to the BTS genome as well as to the genomes of other bean cultivars. The T _m of hybrids formed between BTS DNA and denatured dsRNA have been estimated.     

Aggregation and Fragmentation of Phaseolus vulgaris Lectin

The effects of temperature on 6-O-α-maltosyl cyclodextrins (G₂-CDs) production from α- maltosylfluoride (α-G₂F) and cyclodextrins (CDs) by the transfer action of debranching enzymes such as pullulanase and isoamylase were studied.

The amounts of 6-O-α-maltosyl α-cyclodextrin (G₂-α-CD) production by purified pullulanase from Aerobacter aerogenes (A-pullulanase) and from Bacillus acidopullulyticus (B-pullulanase) increased with a rise in temperature, e.g., the amounts at 60°C were about 1.5 times higher than those at 30°C. Initial transfer ratios (G₂-α-CD formed/α-G₂F consumed) of A-pullulanase and B- pullulanase were about 62% and 25% (at 40°C), and about 50% and 15% (at 20°C), respectively. The transfer ratios of both A-pullulanase and B-pullulanase in the reaction using β-CD or γ-CD as acceptor also increased with a rise in temperature.

The transfer ratios were little affected by any change in temperature or any kind of acceptor CDs, in the case of isoamylase, and were about 60%.     

Tissue Cultures of Phaseolus vulgaris L.

Abstract

Callus production and plant regeneration from different explants of Phaseolus vulgaris L. cv. Giza are reported. Calli cultures were induced from leaf, hypocotyl, embryo and root explants. Rapid growth of callus was achieved by leaf explants cultured on MS salts, B5 vitamins and supplemented with 2,4— dichlorophenoxyacetic acid (2, 4—D)+0.5 mg/l kinetin (kin). Addition of casein hydrolysate at 2 g/l to maintenance medium enhanced callus growth and hindered the early appearance of necrotic parts. This report also provides a detailed method for production of multiple shoots directly from the wounded edges of immature cotyledon explant via organogenesis on 1 mg/l benzyladenine (BA) or indirectly on 0.5 mg/l naphthaleneacetic acid (NAA)+2 mg/l BA. The regeneration of bean plants through the two ways described here (direct or indirect) may be of use in genetic improvement of bean.     

Control of Thylakoid Growth in Phaseolus vulgaris

An attempt was made to answer whether the extent of thylakoid growth in Phaseolus vulgaris is controlled by a feedback inhibition mechanism, operating after insertion of all of the necessary components of the mature thylakoid, in the right amounts and ratio, or by parameters independent of the developmental stage of the membrane. This was done by following the growth of thylakoids, as monitored by the rate of chlorophyll accumulation and the rate of thylakoid protein synthesis, in etiolated plants exposed either directly to continuous light (transformation of prolamellar body to mature thylakoid) or first to periodic light and then to continuous light (transformation of prolamellar body to primary thylakoids and then to mature thylakoids). It was found that prolonged etiolation has no effect on the rate of thylakoid synthesis in continuous light. However, prolonged preexposure to periodic light diminishes drastically the rate of new thylakoid synthesis in continuous light. Since the thylakoids formed in the latter case are far from being complete, it seems that thylakoid growth can stop long before all of the necessary components are incorporated. Parameters independent of the developmental stage and composition of the membrane, therefore, seem to control membrane growth.     

DNA restriction fragment length polymorphisms correlate with isozyme diversity in Phaseolus vulgaris L.

Summary Genetic variation in Phaseolus vulgaris L. (P. vulgaris) was investigated at the isozyme and DNA levels. We constructed a library of size-selected Pst I clones of P. vulgaris nuclear DNA. Clones from this library were used to examine 14 P. vulgaris accessions for restriction fragment length polymorphisms (RFLPs). DNAs from each accession were analyzed with three restriction enzymes and 18 single copy probes. The same accessions were also examined for variability at 16 isozyme loci. Accessions included four representatives of the T phaseolin group and five representatives each of the C and S phaseolin groups. One member of the S group (the breeding line XR-235-1-1) was derived from a cross between P. vulgaris and P. coccineus. Isozymes and RFLPs revealed very similar patterns of genetic variation. Little variation was observed among accessions with C and T phaseolin types or among those with the S phaseolin type. However, both isozyme and RFLP data grouped accessions with S phaseolin separately from those accessions with C or T phaseolin. The highest degree of polymorphism was observed between XR-235-1-1 and members of the C/T group. RFLP markers will supplement isozymes, increasing the number of polymorphic loci that can be analyzed in breeding, genetic, and evolutionary studies of Phaseolus.     

Extensive ribosomal DNA amplification during Andean common bean (Phaseolus vulgaris L.) evolution

The extent of 5S and 45S ribosomal DNA (rDNA) variation was investigated in wild and domesticated common beans (Phaseolus vulgaris) chosen to represent the known genetic diversity of the species. 5S and 45S rDNA probes were localized on mitotic chromosomes of 37 accessions by fluorescent in situ hybridization (FISH). The two 5S rDNA loci were largely conserved within the species, whereas a high variation in the number of 45S rDNA loci and changes in position of loci and number of repeats per locus were observed. Domesticated accessions from the Mesoamerican gene pool frequently had three 45S rDNA loci per haploid genome, and rarely four. Domesticated accessions from Andean gene pool, particularly from the race Peru, showed six, seven, eight or nine loci, but seven loci were found in all three races of this gene pool. Between three and eight loci were observed in accessions resulting from crosses between Andean and Mesoamerican genotypes. The presence of two to eight 45S rDNA loci in wild common beans from different geographic locations indicates that the 45S rDNA amplification observed in the Andean lineage took place before domestication. Our data suggest that ectopic recombination between terminal chromosomal regions might be the mechanism responsible for this variation.