Polytene chromosomes of Simulium craigi (Diptera: Simuliidae)

Simulium craigi Adler and Currie is a polymorphic species based on polytene chromosome banding patterns in the long arm of chromosome III (IIIL). Three cytotypes are described based on the predominant IIIL sequences. These correspond to three broad geographic areas: cytotype CC from Pennsylvania; cytotype AF from Ontario and Manitoba; and cytotype ACF/BCF from New Hampshire. In the absence of sympatric populations, these cytotype differences are best explained by clinal variation within a single species. The relationship of S. craigi to other described members of the S. vernum group is discussed.     

Lectin-gene expression in pea (Pisum sativum L.) roots

The expression of a lectin gene in pea (Pisum sativum L.) roots has been investigated using the copy DNA of a pea seed lectin as a probe. An mRNA which has the same size as the seed mRNA but which is about 4000 times less abundant has been detected in 21-d-old roots. The probe detected lectin expression as early as 4 d after sowing, with the highest level being reached at 10 d, i.e. just before nodulation. In later stages (16-d- and 21-d-old roots), expression was substantially decreased. The correlation between infection by Rhizobium leguminosarum and lectin expression in pea roots has been investigated by comparing root lectin mRNA levels in inoculated plants and in plants grown under conditions preventing nodulation. Neither growth in a nitrate concentration which inhibited nodulation nor growth in the absence of Rhizobium appreciably affected lectin expression in roots.Abbreviation cDNA copy DNA - poly(A)⁺RNA polyadenylated RNA     

Polytene chromosomes of an archipelagic subgenus, <Emphasis Type="Italic">Inseliellum</Emphasis> (Diptera: Simuliidae)

The black fly subgenus Inseliellum is present on a series of archipelagos in the South Pacific. In this study, larval polytene chromosome maps of six Inseliellum species are presented. Chromosomal relationships among taxa were determined through shared fixed inversions or chromosomal landmark positioning. Three fixed inversions (IL-2, IIS-1, and IIIS-1) were shared among species, as was the position of the nucleolar organizer (NO) (IL or IIL). Comparisons to two previously studied species of Inseliellum are included to produce a cytological transformation series among eight taxa. The NO position defines two clades in the phylogeny of Inseliellum, herein named the NO-IL and NO-IIL clades. The utility of this cytological data set is discussed.     

Isozyme variation and alleged progenitor-derivative relationships in theMedicago murex complex (Fabaceae)

Chromosomal studies ofMedicago lesinsii (n = 8) and its close relativeM. murex (n = 7) have led to the competing hypotheses that the latter is derived directly from the former, or that both originated from a common ancestor. In contrast to the relatively variableM. murex, M. lesinsii proved to be almost uniform isozymically, except that most populations of Greece differed by one allele from plants of the remainder of the range. This Greek variant ofM. lesinsii was indistinguishable from one of the isozyme variants ofM. murex. The greater level of allozyme variation inM. murex was consistent with its greater ecological amplitude and competitive ability. Also, this suggests thatM. murex is unlikely to have originated directly from the less variableM. lesinsii. The data suggest that either both species originated from a common ancestor, or that the n = 8 species evolved from the n = 7 species, a mode of chromosome evolution not previously hypothesized for the genus.     

Karyotype and C-banding inTrigonella sectionFoenumgraecum (Fabaceae)

The six species of the sectionFoenum-graecum ofTrigonella have the same chromosome number, 2n = 16.T. gladiata andT. cariensis have fairly symmetrical karyotypes, while those ofT. foenum-graecum, T. berythea, T. macrorrhyncha andT. cassia are asymmetrical. C-bands are present in all six species but the number of bands and their positive vary considerably among the species. The karyotype evidence suggests that none of the available species of theFoenum-graecum section can be considered as the wild progenitor of fenugreek.     

Glycolytic enzymes in non-photosynthetic plastids of pea (Pisum sativum L.) roots

The presence of the glycolytic enzymes from hexokinase to pyruvate kinase in plastids of seedling pea (Pisum sativum L.) roots was investigated. The recoveries, latencies and specific activities of each enzyme in different fractions was compared with those of organelle marker enzymes. Tryptic-digestion experiments were performed on each enzyme to determine whether activities were bound within membranes. The results indicate that hexokinase (EC 2.7.1.2) and phosphoglyceromutase (EC 5.4.2.1) are absent from pea root plastids. The possible function of the remaining enzymes is considered.Abbreviations GADPH glyceraldehyde 3-phosphate dehydrogenase - PFK phosphofructokinase - PFP pyrophosphate: fructose 6-phosphate 1-phosphotransferase Bronwen A. Trimming gratefully acknowledges the award of a studentship from the Science and Engineering Research Council     

Purification and properties of nitrite reductase from roots of pea (Pisum sativum cv. Meteor)

Nitrite reductase (EC 1.6.6.4) prepared from pea roots was found to be immunologically indistinguishable from pea leaf nitrite reductase. Comparisons of the pea root enzyme with nitrite reductase from leaf sources showed a close similarity in inhibition properties, light absorption spectrum, and electron paramagnetic resonance signals. The resemblances indicate that the root nitrite reductase is a sirohaem enzyme and that it functions in the same manner as the leaf enzyme in spite of the difference in reductant supply implicit in its location in a non-photosynthetic tissue.Abbreviations DEAE diethylaminoethyl - EPR electron paramagnetic resonance - NIR nitrite reductase - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis     

Sex allocation and mating systems in pigeonpea,Cajanus cajan (Fabaceae)

Sex allocation theory predicts that: (1) resources allocated to androecium should decrease with an increase in selfing, (2) a decrease in androecium biomass should be accompanied by an increase in the biomass of pistils, and (3) a decrease in androecium biomass should be coupled with a decrease in flower size, specifically corolla biomass. Another predicted change in reproductive traits associated with variation in selfing concerns seed to ovule ratios, but does not directly stem from sex allocation theory. It has been postulated that seed to ovule ratios should be positively correlated with the amount of selfing. These predictions were tested for six accessions of pigeonpea,Cajanus cajan L., that differed in selfing rates. The results were remarkably in accordance with the predictions. We conclude that sex allocation theory provides a powerful tool to understand the evolution of many reproductive traits in plants.     

Fruit dimorphism inPhaseolus sublobatus (Fabaceae) and its evolutionary significance

Populations of the annualPhaseolus sublobatus from different ecogeographical zones are genetically differentiated. In twelve populations from the western ghats (Maharashtra range) chasmogamous flowers are arranged in peduncled capitate racemes borne in leaf axils of higher nodes. One population (Poona Race S₄) has additional inflorescences, also with chasmogamous flowers, on the main axis between the cotyledonary node and the ground. When the pods of these flowers ripen, the inflorescence gradually coils and, eventually, gets bury the fruits in the soil. This phenomenon is not known in any other plant.—The seed-coat patterns as revealed by SEM, and germination behaviour of both aerial and subterranean seeds are similar, and both types of seeds lack dormancy.—Heavy seed predation selection pressure is probably the principal cause for the evolution of fruit dimorphism inP. sublobatus. The origin of geocarpy in relation to fruit dimorphism and seed predation is discussed.     

An analysis of the B genome speciesArachis batizocoi (Fabaceae)

Arachis batizocoi Krap. & Greg. is a suggested B genome donor to the cultivated peanut,A. hypogaea L. Until recently, only one accession of this species was available in U.S.A. germplasm collections for analyses and species variability had not been documented. The objective of this study was to determine the intraspecific variability ofA. batizocoi to better understand phylogenetic relationships in sect.Arachis. Five accessions of the species were used for morphological and cytological studies and then F₁ intraspecific hybrids analyzed. Some variation was observed among accessions—for example, differences in seed size, plant height and branch length. The somatic chromosomes of accessions 9484, 30079, and 30082 were nearly identical, whereas, the karyotypes of accessions 30081 and 30097 have several distinct differences. For example, 30081 had significantly more asymmetrical chromosomes 2 and 6 and more median chromosomes 7 and 10, and 30097 had significantly more asymmetrical chromosomes 3 and 10 and more median chromosomes 1 and 5 than accessions 9484, 30079, and 30082. All F₁ hybrids among accessions were highly fertile. Meiotic observations indicated that hybrids among accessions 9484, 30079, or 30082 had mostly bivalents. However, quadrivalents were observed when either 30081 or 30097 was crossed with the above three accessions and 30081 × 30097 had quadrivalents, hexavalents and octavalents. The presence of translocations is the most likely cause of multivalent formation inA. batizocoi hybrids. Cytological evolution via translocations has apparently been an important mechanism for differentiation in the species.Paper No. 12382 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695-7643.     

The supply of reducing power for nitrite reduction in plastids of seedling pea roots (Pisum sativum L.)

Plastids were separated from extracts of pea (Pisum sativum L.) roots by sucrose-density-gradient centrifugation. The incubation of roots of intact pea seedlings in solutions containing 10 mM KNO₃ resulted in increased plastid activity of nitrite reductase and to a lesser extent glutamine synthetase. There were also substantial increases in the activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. No other plastid-located enzymes of nitrate assimilation or carbohydrate oxidation showed evidence of increased activity in response to the induction of nitrate assimilation. Studies with [1-¹⁴C]-and [6-¹⁴C]glucose indicated that there was an increased flow of carbon through the plastid-located pentose-phosphate pathway concurrent with the induction of nitrate assimilation. It is suggested that there is a close interaction through the supply and demand for reductant between the pathway of nitrite assimilation and the pentose-phosphate pathway located in the plastid.     

Variability in nuclear DNA content within pigeonpea,Cajanus cajan (Fabaceae)

4C DNA values have been estimated in 16 cultivars ofCajanus cajan by cytophotometry. The values range between 6.19 pg to 7.97 pg, a 23.6% variation. The cultivars form four groups which differ significantly from each other but have insignificant difference within them. The implications of this variability with respect to the heterogeneity and origin of this legume crop are discussed.     

Satellited chromosomes,systematics and phylogeny inTaraxacum (Asteraceae)

A survey is made of the occurrence, nature and frequency of satellited chromosomes in the agamospermous genusTaraxacum. Species belonging to the 10 sections thought to be most primitive in the genus lack satellited chromosomes. In most other sections, a characteristic satellited chromosome is seen with a large euchromatic region distal to the presumed nucleolar oraniser region (NOR). In sections of a precursor type, there is always one chromosome of this Taraxacum type per haploid genome. In sections thought to be of an advanced type the number of such satellited chromosomes is very unstable, sometimes even within the same tissue. In sectionHamata, two such satellited chromosomes are invariably found in triploids. This finding strongly supports the integrity of this section, suggests that the species of the section are monophyletic, and have evolved from a single ancestor subsequent to the occurrence of obligate agamospermy. In three sections of the genus, satellited chromosomes of the conventional type with a very small distal euchromatic region distal to the NOR are reported for the first time in the genus.     

Isozyme polymorphism in some yellow- and blue-floweredVigna species complexes (Fabaceae, Phaseoleae)

An electrophoretic comparison of variation at 28 isozyme loci was performed for 58Vigna accessions belonging to theV. luteola, V. ambacensis, andV. racemosa groups of species. In all three groups, strong divergence is noted between results and actual nomenclature.     

Variation at isozyme loci in wildVigna unguiculata (Fabaceae,Phaseoleae)

An electrophoretic comparison of variation at 37 presumptive isozyme gene loci was performed for 55 wildVigna unguiculata accessions. The analysis included seven subspecies, covering the whole range of variation available in wildVigna unguiculata. The results of the isoenzymatic study broadly confirmed the previous infraspecific classification inferred from morphological data. Although the southern taxa (e.g., subsp.tenuis, subsp.stenophylla) are as yet too poorly sampled to discuss in depth, wildVigna unguiculata can be divided into one mainly autogamous annual group (including subsp.pubescens and var.spontanea) and several widely divergent perennial subspecies.     

Distribution of glucose/mannose-specific isolectins in pea (Pisum sativum L.) seedlings

We report on the distribution and initial characterization of glucose/mannose-specific isolectins of 4- and 7-d-old pea (Pisum sativum L.) seedlings grown with or without nitrate supply. Particular attention was payed to root lectin, which probably functions as a determinant of host-plant specificity during the infection of pea roots by Rhizobium leguminosarum bv. viciae. A pair of seedling cotyledons yielded 545±49 g of affinity-purified lectin, approx. 25% more lectin than did dry seeds. Shoots and roots of 4-d-old seedlings contained 100-fold less lectin than cotyledons, whereas only traces of lectin could be found in shoots and roots from 7-d-old seedlings. Polypeptides with a subunit structure similar to the precursor of the pea seed lectin could be demonstrated in cotyledons, shoots and roots. Chromatofocusing and isoelectric focusing showed that seed and non-seed isolectin differ in composition. An isolectin with an isoelectric point at pH 7.2 appeared to be a typical pea seed isolectin, whereas an isolectin focusing at pH 6.1 was the major non-seed lectin. The latter isolectin was also found in root cell-wall extracts, detached root hairs and root-surface washings. All non-seed isolectins were cross-reactive with rabbit antiserum raised against the seed isolectin with an isolectric point at pH 6.1. A protein similar to this acidic glucose/mannose-specific seed isolectin possibly represents the major lectin to be encountered by Rhizobium leguminosarum bv. viciae in the pea rhizosphere and at the root surface. Growth of pea seedlings in a nitrate-rich medium neither affected the distribution of isolectins nor their hemagglutination activity; however, the yield of affinity-purified root lectin was significantly reduced whereas shoot lectin yield slightly increased. Agglutination-inhibition tests demonstrated an overall similar sugar-binding specificity for pea seed and non-seed lectin. However root lectin from seedlings grown with or without nitrate supplement, and shoot lectin from nitrate-supplied seedlings showed a slightly different spectrum of sugar binding. The absorption spectra obtained by circular dichroism of seed and root lectin in the presence of a hapten also differed. These data indicate that nutritional conditions may affect the sugar-binding activity of non-seed isolectin, and that despite their similarities, seed and non-seed isolectins have different properties that may reflect tissue-specialization.Abbreviations IEF isoelectric focusing - MW molecular weight - pI isoelectric point - Psl1, Psl2 and Psl3 pea isolectins - SDSPAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis The authors wish to thank Professors L. Kanarek and M. van Poucke for helpful discussions.     

Soluble and microsomal glutatione S-transferase activities in pea seedlings (Pisum sativum L.)

Epicotyl and primary leaves of pea seedlings (Pisum sativum L., var. Alaska) were found to contain soluble and microsomal enzymes catalyzing the addition of glutathione to the olefinic double bond of cinnamic acid. Glutathione S-cinnamoyl transfer was also obtained with enzyme preparations from potato slices and cell suspension cultures of parsley and soybean.The pea transferases had pH-optima between pH 7.4 and 7.8 K_m-values were 0.1–0.4 mM and 1–4 mM for cinnamic acid and glutathione, respectively. V-values were between 2–15 nmol mg^-1 protein x min.Chromatography on Sephacryl S-200 indicated that the soluble pea glutathione S-cinnamoyl transferase activity existed in molecular weight forms of 37,000, 75,000, and 150,000. The glutathione-dependent cleavage of the herbicide fluorodifen was catalyzed by a different soluble enzyme activity which eluted in molecular weight positions of 47,000 and/or 82,000.The microsomal fraction from pea primary leaves also catalyzed the conjugation of the carcinogen benzo[]pyrene with glutathione.Abbreviations GSH glutathione - DDE 1,1-Dichloro-2,2-bis-(4-chlorophenyl)-ethylene - DDMU l-Chloro-2,2-bis-(4-chlorophenyl)-ethylene     

The immuno-histochemical localization of lectin in pea seeds (Pisum sativum L.)

The lectin from the garden pea (Pisum sativum L.) has been localized at the ultrastructural level by the unlabeled peroxidase-antiperoxidase procedure of L.A. Sternberger et al. (1970, J. Histochem. Cytochem 18, 315–333) in 24 h imbibed seeds. Upon examination by light microscopy and transmission electron microscopy, the lectin was only found in the protein bodies of cotyledons and embryo axis. Cell walls as well as membraneous fractions were completely devoid of lectin. These results are discussed in relation to the possible physiological function of seed lectins.Abbreviations PBS phosphate-buffered saline - TBS Tris-buffered saline - PAP-complex horseradish peroxidase-antihorseradish peroxidase soluble complex - NGS normal goat serum - TBS^* Tris-buffered saline containing 0.5 M NaCl, pH 7.6     

The major albumin protein from pea (Pisum sativum L.)

The major albumin protein in storage parenchyma tissue of developing peas has been localised at an ultrastructural level by immunocytochemistry. Tissue was fixed in buffered aldehyde and embedded in LR White resin which was polymerised by addition of catalyst. Sections were labelled by the indirect method of absorption of Protein A-gold to specifically bound antibodies. This method gives high levels of specific labelling on sections which retain good ultrastructural preservation and have high contrast after conventional staining. The albumin is located throughout the cytoplasm although no labelling was found associated with the endoplasmic reticulum, Golgi apparatus, vacuoles-protein bodies or other organelles.Abbreviation PMA pea major albumin protein     

Analysis of nucleolus organizer regions (NORs) in mitotic and polytene chromosomes ofPhaseolus coccineus by silver staining and Giemsa C-banding

Chromosomes with active nucleolus organizer regions (NORs) were visualized in root tip metaphases ofPhaseolus coccineus using the silver staining technique. A mean number of 5.5 Ag-NORs per cell was observed in 54 cells from eight plants. In the endopolyploid nuclei of the suspensor the silver technique did not demonstrate the reported specificity for nucleolus organizer activity, because there was usually pale staining of nucleoli and preferential staining of heterochromatic regions in the polytene chromosomes including pericentromeric material, telomeres and NORs. The mean number of NORs per nucleolus as detected by this method was 5.8 (28 nucleoli analysed). Using a modified preparation technique, giant chromosomes stained pale, but nucleoli of suspensor cells displayed darkly silver staining internal domains, each of which originating from a nucleolus organizer.—Giemsa C-banding of endopolyploid suspensor nuclei revealed C-positive nucleolus organizers with darkly staining intranucleolar fibrils. The latter were frequently involved in inter-NOR associations. In 34 nucleoli analysed, the mean number of Giemsa C-positive NORs per nucleolus was 6.0.Dedicated to Professor Dr.Lothar Geitler on the occasion of his 80th birthday.