Matromorphy in Pisum sativum L.

Summary The possibility of obtaining instant pure breeding lines by matromorph seed development in Pisum sativum L. has been investigated. Two types of maternal parents, namely, homozygous for the recessive marker genes and heterozygous for the dominant marker genes were pollinated with Lathyrus odoratus and the P174 variety of Pisum sativum L. carrying dominant markers. For both pollinators, induction of matromorphy by prickle pollination, irradiated pollen and IAA treatment was examined. Promising matromorphs were identified in the M₁ generation which were studied in the M₂ generation for assessing their genetic status with respect to homozygosis. The success of pod set varied from zero to 28% with a varying number of matromorphic seeds following different treatments. The possible mechanisms for matromorphic origin have been discussed. The evidence presented herein favours induction of matromorphy in peas for the production of homozygous stocks. In addition, the recovery of double recessive seed markers of the maternal parents along with plant markers from the paternals has prospective implications in plant breeding as an alternative tool to recurrent back crossing.     

Stomata on the Primary Root of Ceratonia siliqua

Anomocytic stomatal complexes observed with light and scanningelectron microscopes on the primary roots of Ceratonia siliqua(carob tree) are described. Stomata are randomly distributedthroughout the surface of the root zones which possess maturevascular tissues, i.e. from the zone of root hairs to the transitionzone. Stomatal orientation does not follow that of the rootepidermal cells whilst their distribution does not seem to forma regular pattern. Ceratonia siliqua, primary root, stomata     

Biologically Active Oligosaccharides from Pectins of Pisum sativum L. Seedlings Affecting Root Generation

Two physiologically active oligosaccharide fractions were isolated from pectin of Pisum sativum L. cell wall after its partial acid hydrolysis. These fractions displayed stimulating and inhibiting effects on root formation in thin-layer explants. The subsequent separation of these fractions by gel permeation and anion-exchange chromatography resulted in fractions with effective concentrations two orders of magnitude lower than the concentrations of the initial fractions. The resulting oligosaccharides displayed their effect on the earliest stage of the rhizogenesis associated with formation of root primordias. The rhizogenesis-inhibiting fraction suppressed cell division by 30-50%. The stimulating fraction mainly contained fragments of xyloglucan and galactan, and the inhibiting fraction contained fragments of xyloglucan, galactan, and arabinan. The polymerization degrees of the stimulating and of the inhibiting oligosaccharides were 10-11 and 5-6, respectively.     

Glutamate dehydrogenase from Pisum sativum L.

A 2–8-fold increase in the activity of glutamate dehydrogenase (GDH), accompanied by an alteration of the GDH isoenzyme pattern, was observed in detached pea shoots floated on tap water (preincubated shoots). Sugars supressed the process, whereas NH ₊ ⁴ and various metabolites as well as inhibitors of energy metabolism and protein synthesis were ineffective. The subcellular distribution pattern revealed evidence that the GDH isoenzymes are exclusively located in the mitochondrial matrix. The alterations in GDH activity occurring in preincubated shoots are restricted to the mitochondria.An experimental device suitable for studying the GDH function in isolated intact mitochondria has been established. Using [¹⁴C] citrate as the carbon source and hydrogen donor, the mitochondria synthesized considerable amounts of glutamate upon addition of NH ₊ ⁴ . The rates of glutamate formation in dependency of increasing NH ₊ ⁴ levels follow simple Michaelis-Menten kinetics. Half-saturation concentrations of NH ₊ ⁴ of 3.6±1.2 mM; 1.9±0.06 mM and 1.6±0.1 mM were calculated for the mitochondria isolated from pea shoots, roots, and preincubated shoots, respectively. The results are discussed in relation to the possible role of GDH in NH_+/4 assimilation at elevated intracellular NH_+/4 levels.Abbreviations GDH Glutamate dehydrogenase - MDH malate dehydrogenase - GOT aspartate aminotransferase - SDH succinate dehydrogenase - HEPES 4-(2-hydroxyethyl)-1-piperazineethan-sulfonic acid - BSA bovine serum albumin - TPP thiamine pyrophosphate - DNP 2,4-dinitrophenol - CCCP carbonyl cyanide m-chlorophenylhydrazone - DCPIP 2,6-dichlorophenolindophenol Dedicated to Professor Dr. Maximilian Steiner on the occasion of his 75th birthday     

Gibberellin translocation in Pisum sativum L.

The physiological and biochemical consequences of treating Le (tall) and le (dwarf) pea seedlings with varying quantities of the gibberellins [³H]GA₂₀ and GA₁ have been investigated. Although the percentage uptake of these compounds from the site of application on the 3 stipules was low and most of the applied GA remained unmetabolised in situ, the quantitative relationship between GA translocation and GA dosage was found to be linear for GA₁ but saturating for GA₂₀. The movement of the GAs and their subsequently produced metabolites was mainly acropetal. They accumulated in greatest quantity in the apical extremities of the shoot. Overall, the extent to which GA₂₀ was metabolished in le seedlings was considerably less than in Le pea seedlings. Although all le tissues contained significantly less [³H]GA₁ than their Le counterparts, phenotypic effects of the le mutation were apparent only on internode and tendril development. Increased tissue growth, consequent upon GA treatment, was also apparent only in the internodes and tendrils of le plants. For internodes, GA₁ content determined the mid-logarithmic-phase growth rate and, consequently, final length. For tendrils, GA₂₀ rather than GA₁ may be the primary stimulatory agent.Abbreviations GA gibberellin - HPLC high-performance liquid chromatography - 1–6 consecutive developmental numbering system for plant tissues/organs as shown in Fig. 1 The author gratefully acknowledges financial support from Imperial Chemical Industries, Plant Protection, Jealott's Hill, Bracknell, Berks., UK and the Science and Engineering Research Council.     

Ethylene metabolism in Pisum sativum L.

The possible role of C₂H₄ metabolism in mediating the responses of plants to C₂H₄ is re-examined. It is demonstrated that (i) the effects of inhibitors upon C₂H₄ action do not correspond with their effects on metabolism, (ii) elicitors of C₂H₄ effects do not have appropriate effects on C₂H₄ metabolism, (iii) inhibitors of C₂H₄ metabolism do not affect the response of plants to C₂H₄. It is concluded that metabolism of C₂H₄ is not linked to the mode of action of the growth regulator.Abbreviations DTC sodium diethyldithiocarbamate - FW fresh weight     

Root system growth and nodule establishment on pea (Pisum sativum L.)

Development of the root system, appearance of nodules, and relationshipsbetween these two processes were studied on pea (Pisum sativumL., cv. Solara). Plants were grown in growth cabinets for 4weeks on a nitrogen—free nutrient solution inoculatedwith Rhizobium leguminosarum. Plant stages, primary root length,distance from the primary root base to the most distal first-orderlateral root, and distance from the root base to the most distalnodule, were recorded daily. Distribution of nodules along theprimary root and distribution of laterals were recorded by samplingroot systems at two plant stages. Primary root elongation ratewas variable, and declined roughly in conjunction with the exhaustionof seed reserves. First-order laterals appeared acropetallyon the primary root. A linear relationship was found betweenthe length of the apical unbranched zone and root elongationrate, supporting the hypothesis of a constant time lag betweenthe differentiation of first-order lateral's primordia and theiremergence. Decline of the primary root elongation rate was precededby a reduction in density and length of first-order laterals.Nodules appeared not strictly but roughly acropetally on theprimary root. A linear relationship was found between the lengthof the apical zone without nodule and root elongation rate,supporting the hypothesis of a constant time lag between infectionand appearance of a visible nodule. A relationship was foundbetween the presence/absence of nodules on a root segment andthe root elongation rate between infection and appearance ofnodules on the considered root segment. Regulation of both processesby carbohydrate availability, as a causal mechanism, is proposed. Key words: Pisum sativum L, root system, nodules     

Induction of Root Nodule Senescence by Combined Nitrogen in Pisum sativum L

Root nodule senescence induced by nitrate and ammonium in Pisum sativum L. was defined by determining nitrogenase activity and leghemoglobin content with the acetylene reduction and pyridine hemochrome assays. Root systems supplied with 100 mm KNO(3) or 100 mm NH(4)Cl exhibited a decrease in nitrogenase activity followed by a decline in leghemoglobin content. Increasing the CO(2) concentration from 0.000320 atm to 0.00120 atm had no effect on the time course of root nodule senescence when 20 mm KNO(3) was supplied to the roots; in vitro nitrate reductase activity was detected in leaves and roots, but not bacteroids. Nitrate appeared in leaves, roots, and the nodule cytosol fraction but not bacteroids when 20 mm KNO(3) was supplied to roots. When nitrate entered through the shoots, however, no root nodule senescence was observed, and no nitrate was detected in root or nodule cytosol fractions although nitrate and nitrate reductase were found in leaves. The results suggest that nitrate does not induce root nodule senescence through competition between nitrate reductase and nitrogenase for products of photosynthesis.     

Cell Division Heterogeneity in the Primary Meristems of Pisum sativum Root Tips after Excision

Root tips (1.0 cm) were excised, transferred to culture medium,sampled at intervals, embedded in paraffin and sectioned. Themitotic index in each primary meristem in the 2.0 mm tips wasreduced immediately after excision. After 8–12 h mitosisresumed. The position of mitotic figures in the protoderm, groundmeristem, procambium, and root cap was determined. The greatestnumber of mitotic figures occurred in the procambium, and uponexcision the smallest percent reduction also occurred in thisregion. The ground meristem showed the greatest reduction inmitotic figures. After excision, the relative contribution tothe total number of mitotic figures increased in the procambiumtissue and decreased in the ground meristem. Cell division inall primary meristems of the root tip is reduced after tip excision,but the ground meristem (cortical region) is the primary targettissue.     

Orientation of Wall Microfibril Deposition in Root Cells of Pisum sativum L. var Alaska

The arrangement of wall microfibrils on the inner surface ofcortical cells in pea roots was observed by a replica method.In the elongating region, microfibrils were deposited transverselyto the root axis. After cell elongation stopped, the orientationof microfibril deposition changed discontinuously from a transverseto an oblique one. The change occurred at 6–7 mm fromthe root tip. The oblique orientation seemed to change discontinuouslyto another oblique one as time passed. (Received January 24, 1986; Accepted May 15, 1986)     

Immunofluorescence Microscopy of Microtubule Arrangement in Root Cells of Pisum sativum L. var Alaska

The arrangement of wall microtubules (MTs) in Pisum sativumroots was viewed immunofluorescently using cryosectioning. Mostcells in the tip region of pea roots (0–2 mm from tip)had wall MTs arranged transversely to the root axis. In theregion elongating at a higher rate (2–4 mm), wall MTsof epidermal, cortical and stelar cells were all transverselyarranged. In the region of about 5 mm from the tip, in whichcell elongation had already ceased, wall MTs in cortical cellschanged from a transverse to an oblique arrangement in relationto the root axis. Some cells had a crossed arrangement of wallMTs, which was interpreted as representing two sets of unidirectional,oblique wall MTs in opposite cell cortices of a single cell.This change was completed within a region of 1-mm width. Sinceroots elongated at a rate of 0.6 mm h^–1, it means thatthe arrangement of wall MTs changed within 2 h. An oblique arrangementof wall MTs was also observed in stelar cells. As the cellsaged, the oblique arrangement tended to change to a steeperor even a longitudinal one. (Received January 24, 1986; Accepted May 15, 1986)     

Glycosidases from Cotyledons of Pisum sativum L.

-Mannosidase and ß-N-acetylglucosaminidase were purifiedfrom extracts of cotyledons of germinating Pisum sativum L.A 13-fold purification of a-mannosidase free from ß-N-acetylglucosaminidaseactivity was achieved by precipitation in ammonium sulphate,column chromatography on DEAE-cellulose, and treatment with2 M pyridine. ß-N-Acetylglucosaminidase was purified200-fold by the use of (NH₄)₂SO₄, and chromatography on ConcanavalinA¹-Sepharose and Sephacryl-200. This preparation showed no measurablecontamination by -mannosidase activity. Both glycosidases appearto be glycoproteins and demonstrate optimal activity at pH valuesof 4.0–4.5. Both glycosidases appear to have very similarmolecular weights, with -mannosidase being slightly larger thanß-N-acetylglucosaminidase. An extensive search forthe activity of aspartylglycosylamine amido hydrolase in peacotyledons proved unsuccessful.     

Identification of Cytokinins of Root Nodules of the Garden Pea, Pisum sativum L

Five cytokinin activities which induced soybean callus proliferation were detected in ethanol extracts of root nodules of the garden pea (Pisum sativum L., cv. Little Marvel). The most active factors among them were identified as zeatin and its riboside on the basis of their mobility on thin layer chromatography in three solvent systems. Smaller activities of zeatin ribotide, isopentenyladenine and its riboside were also detected. Cytokinin activity gradually decreased with the cultivation period, but no qualitative change in the active compounds was found.     

Apical Meristem Activity and Lateral Root Anlage Development in Excised Roots of Pisum sativum L.

The initiation and subsequent emergence of lateral roots fromthe tissues of the primary has been examined in attached andexcised roots of Pisum. Lateral anlage inception took placein cultured roots which were 1 and 4 cm in length at the timeof excision. However, whereas a few primordia completed theirdevelopment and grew out as emerged laterals from those excisedroots which were 4 cm long, at the onset of culturc none appearedon those which had an initial length of 1 cm. The changes which took place in the rate of cell proliferationin the apical millimetre of each batch of cultured roots withtime following excision, were followed and related to the appearanceor otherwise of secondary roots on the cultured primaries. Pisum sativum L., garden pea, anlage, primodium, emerged lateral, apical meristem, cell proliferation     

Carnitine acyltransferases in chloroplasts of Pisum sativum L.

Carnitine-acetyltransferase (EC 2.3.1.7) and carnitine-palmitoyltransferase (EC 2.3.1.21) activities were shown to be present in chloroplasts of green pea leaves and possibly to occur in leaf mitochondrial and peroxisomal fractions. A role for the enzymes in the transfer of acyl groups across membranes is suggested.     

Fruit-set of unpollinated ovaries of Pisum sativum L.

The influence of removing the apical shoot and different leaves above and below the flower on the fruit-set of unpollinated pea ovaries (Pisum sativum L. cv. Alaska) has been studied. Unpollinated ovaries were induced to set and develop either by topping or by removing certain developing leaves of the shoot. Topping had a maximum effect when carried out before or on the day of anthesis, and up to four consecutive ovaries were induced to set in the same plant. The inhibition of fruit-set was due to the developing leaves and not to the apex. The third leaf above the first flower, which had a simultaneous development to the ovary, had the stronger inhibitory effect on parthenocarpic fruit-set. The application of different plant-growth regulators (indoleacetic acid, naphthylacetic acid, 2,4-dichlorophenoxyacetic acid, gibberellic acid, benzyladenine and abscisic acid) did not mimic the negative effect of the shoot.Abbreviations CCC (2-chloroethyl)trimethylammonium chloride - MH maleic hydrazide - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - 6-BAP benzyladenine - ABA abscisic acid     

In vitro clonal propagation of Pisum sativum L.

A system of in vitro clonal propagation has been developed in Pisum sativum L. (cv. Bohatýr). A modified MS-medium supplemented with 20 M 6-benzylaminopurine (BAP) and 0.1 M -naphthaleneacetic acid (NAA) was used to induce multiple shoot formation from shoot apices, axillary buds of the first normal leaf, axillary buds of the first and second primary scales and axillary buds of cotyledons of 4 to 6 day old pea seedlings. Meristem explants maintained a high proliferation ability in each subculture in the course of 20 months of the culture. Regenerated shoots were rooted in the same basal medium containing 5 M NAA. Rooted plants were cultured in hydroponic pots filled with half-strength MS-medium to attain anthesis and seed maturity. The phenotypic uniformity of the regenerants was evaluated. Cytological investigation confirmed the diploid stage (2n=14) of regenerants and their progeny. Histological studies revealed that proliferating shoots originated from axillary and adventitious buds. In vitro propagation is discussed as related to pea breeding.     

Regeneration of the Root Cap of Zea mays L. and Pisum sativum L.: A Study with the Scanning Electron Microscope

Removal of the root cap from a root apex initiates regenerationof a new cap. The process has been followed using scanning electronmicroscopy. Quantitative data have been obtained for the growthin area of the exposed acroscopic surface of the quiescent centre(QC) and the increase in volume of the regenerating cap tissue.In Zea the surface of the QC shows an initial rapid increasein area followed by a slower increase. In Pisum the surfacearea increases uniformly, a rapid initial phase being absent.Together with observations on the behaviour of an incision atthe exposed surface, the results indicate that in Zea the capnormally imposes a constraint upon radial growth at the acroscopicsurface of the QC; in Pisum the QC appears not to be so constrained.The different responses may be related to the different arrangementsof cells at the apex of the meristem of these two species. Zea mays, Pisum sativum, maize, peao, scanning electron microscopy, root apex, regeneration     

A Cotyledonary Inhibitor of Root Nodulation in Pisum sativum

Root nodule formation was studied in 11-day-old seedlings of Pisum sativum L. cv. Alaska, which were inoculated with Rhizobium leguminosarum at the time of planting. On intact plants an identical nodulation pattern was observed in the lateral roots attached to the two xylem strands connected to the cotyledons. When one cotyledon was removed before germination, however, a highly significant increase in nodultion was observed on the lateral roots attached to the xylem strand which no longer was connected to a cotyledon. Excision of one cotyledon also caused an alteration in the radial location of root nodules on the primary root. Under these conditions there was a distinct promotion of nodular proliferations in the root cortex opposite the primary phloem poles. The fact that removal of one cotyledon increased nodulation on the lateral roots but had no effect on the rhizobial infection of lateral root hairs suggested that a cotyledonary inhibitor acts at a step between the infection process and the appearance of a macroscopic nodule. The data were interpreted in terms of an inhibitor of cortical cell division which is translocated from the cotyledons to the developing root via the phloem.