Identification of ultraviolet-B responsive genes in the pea, Pisum sativum L.

In the present work, UV-B-repressible and UV-B-inducible genes were identified in the pea, Pisum sativum L., by rapid amplification of 3' cDNA ends through use of the polymerase chain reaction. Of the UV-B-repressible clones, psUVRub and psUVDeh represent genes encoding Rubisco activase and dehydrin, respectively. A third clone, psUVZinc, did not correspond closely in overall nucleotide sequence to any gene registered in GenBank; however, a short deduced peptide shared similarity with the photosystem-II reaction center X protein of the chlorophyll a+c-containing alga, Odontella sinensis. The UV-B-inducible clones, psUVGluc, psUVAux and psUVRib, were related to genes encoding #-1, 3-glucanase, auxin-repressed protein, and a 40S ribosomal protein, respectively. The modulation of these pea genes indicates how UV-B, through its actions as a physical stressor, affects several important physiological processes in plants.     

Immunoelectrophoretic analysis of seed proteins from Pisum sativum L.

Summary Soluble proteins of pea seed were investigated by quantitative immunological methods. Vicilin, legumin, pea seed lectin (PEA), 26 albumins and a globulin (B₁) were detected and observed during seed development, germination and under different extraction and fractionation procedures. Vicilin and legumin were found to be immunologically distinctly different. Legumin was found to be comprised of two similar proteins, Legumin species I and II. Vicilin, but no legumin, was detected in the embryonic axis.Three albumins, B₁ and PEA were found to be synthesized after the onset of legumin synthesis.Among the pea lines investigated, one line exhibited distinct differences with respect to the albumins and PEA.Some observations indicate that PEA might interact with other seed proteins of pea.     

Dominance,overdominance and epistasis in Pisum sativum L.

Summary Dominant genes are the main cause of the heterosis induced by fasciated mutants of different lines of Pisum sativum. Most of these cases were originally interpreted by different authors as examples of monogenic overdominance. Several not-closely-linked genes appear to have mutated simultaneously in most of the fasciated lines. Although fasciation itself is recessive, other mutant characters, such as lateness, increased stem length (number and length of internodes) and, in part, seed production per plant, show dominant inheritance. The latter two features are, however, to a considerable extent suppressed in the fasciated lines by unfavourable gene-interactions (epistasis). Crossing these lines with non-fasciated ones shows that the epistatic genes are recessive and the dominant genes are then no longer hindered in their action. By eliminating the epistatic genes from the genomes of fasciated lines by recombination, the heterosis phenomenon has been fixed on six independent occasions for different lines. The fasciata genes themselves were found to be the most probable cause of these cases of recessive epistasis. The question whether different kinds of fasciation affect heterosis differently is examined. Recessive epistasis and dominance explain most of the quantitative distinctions between the different hybrids. In addition, one example of heterosis between non-fasciated lines is given and the possible meaning of the overall results for plant breeding and population genetics is mentioned.     

Effect of clinorotation on the leaf mesophyll structure and pigment content in Arabidopsis thaliana L. and Pisum sativum L

Properties of mesophyll cells and photosynthetic membranes of Arabidopsis thaliana (L.) Heynh. and Pisum sativum (L.) plants grown in a horizontal clinostat and in control conditions were compared. Obtained data have show that under clinorotation conditions seedlings have experienced the following cell morphology changes structural chloroplast rearrangement in palisade cells, pigment content alteration, and cell aging acceleration.     

The Translocation of 14C-photosynthate in Pisum sativum L.

Short-term studies were undertaken of source and sink relationshipsin Pisum sativum, cultivar Orfac, plants grown in a controlledenvironment. ¹⁴C-distribution assays were conducted after 24or 48 h ¹⁴Cphotoassimilate translocation from a single leafsubtending either a vegetative or a reproductive node. The primaryallocation of ¹⁴C-assimilate was achieved within 24 h: therewas no significant secondary movement of ¹⁴C within the subsequent24 h. The pod was strongly but not exclusively dependent onthe subtending leaf. Out of the total ¹⁴C fixed by a leaf theproportion that was exported within 24 h was related to the¹⁴C-sink capacity of the pods. A rapid non-combustive ¹⁴C-assay method is described whereby¹⁴C-tissue fragments are rendered translucent prior to directscintillation counting of the sample. In terms of cpm per mgobtained the latter method was comparable to a wet combustionmethod adapted for insoluble ¹⁴C-tissue.     

Glucan-phosphorylase forms in cotyledons of Pisum sativum L.: Localization,developmental change,in-vitro translation,and processing

The occurrence, location, and biosynthesis of glucan-phosphorylase (EC 2.4.1.1) isoenzymes were studied in cotyledons of developing or germinating seeds of Pisum sativum L. Type-I and type-II isoenzymes were detected, and were also localized by indirect immunofluorescence using polyclonal anti-type-I or anti-type-II phosphorylase antibodies. Type-I isoenzyme was found in the cytosol of parenchyma cells whereas the type-II enzyme form is a plastid protein which resides either in amyloplasts (in developing seeds) or in proplastids (in germinating seeds). During seed development, type-II phosphorylase was the predominant isoenzyme and the type-I isoenzyme represented a very minor compound. During germination, the latter increased whilst type-II phosphorylase remained at a constant level. In in-vitro translation experiments, type-I isoenzyme was observed as a final-size product with an apparent molecular weight of approx. 90 kDa. In contrast, type-II phosphorylase was translated as a high-molecular-weight precursor (116 kDa) which, when incubated with a stromal fraction of isolated intact pea chloroplasts, was processed to the size of the mature protein (105 kDa).Abbreviations IgG immunoglobulin G - kDa kilodalton - poly(A)⁺ RNA polyadenylated RNA - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis This work has been made possible by grants from the Deutsche Forschungsgemeinschaft. The authors are endebted to Mrs. Karin Niehüser for help in the immunocytochemical studies.     

Catabolism of indole-3-acetic acid in chloroplast fractions from light-grown Pisum sativum L. seedlings

Abstract The catabolism of indole-3-acetic acid was investigated in chloroplast preparations and a crude enzyme fraction derived from chloroplasts of Pisum sativum seedlings. Data obtained with both systems indicate that indole-3-acetic acid undergoes decarboxylative oxidation in pea chloroplast preparations. An enhanced rate of decarboxylation of [1′-¹C]indole-3-acetic acid was obtained when chloroplast preparations were incubated in the light rather than in darkness. Results from control experiments discounted the possibility of this being due to light-induced breakdown of indole-3-acetic acid. High performance liquid chromatography analysis of [2′-¹⁴C]indole-3-acetic acid-fed incubates showed that indole-3-methanol was the major catabolite in both the chloroplast and the crude enzyme preparations. The identification of this reaction product was confirmed by gas chromatography-mass spectrometry when [²H₅]indole-3-methanol was detected in a purified extract derived from the incubation of an enzyme preparation with ³²H₅]indole-3-acetic acid.     

The Effect of Fruit Shading on Yield in Pisum sativum L.

Fruits of Pisum sativum L. cv. Feltham First which initiatesonly one flower per flowering node, were selectively shadedunder varying levels of defoliation. The purpose of the experimentswas to ascertain whether the foliage could compensate for lossof the fruit's contribution to its own growth. There was evidenceof this, but fruit and seed weight per fruit and per plant werereduced by fruit shading at all levels of defoliation. The lossin yield due to shading suggested that the contribution fromthe fruit was at least 12 per cent. The number of seeds whichdeveloped to maturity was the yield component most affectedby treatment. There was no evidence to suggest that shadinghad a different quantitative effect on final weight at differentnodes, but it did increase flower abscission at the first foweringnode in an experiment done at low radiant exposure. In an experimentat higher radiant exposure, very few flowers abscised at theearlier nodes, but leaflet removal reduced final fruit yieldat the first flowering node to a greater degree than at thesecond. These differential responses could contribute to variabilityof seed size in a crop of vining peas. Pisum sativum, pea, fruit, pod, light, shading, photosynthesis, yield     

The major albumin proteins from pea (Pisum sativum L). Purification and some properties.

A scheme is described for the fractionation of pea (Pisum sativum) albumin proteins. By using this scheme, two closely related major albumin proteins have been isolated and purified to homogeneity. The larger protein, designated PMA-L, has Mr approximately 53 000 and consists of two 25 000-Mr subunits, whereas the smaller, PMA-S, has Mr approximately 48 000 and contains two 24 000-Mr subunits. There was no evidence of mixed dimers of the two subunit sizes, despite their close homology as judged by immunological crossreaction, amino acid composition, N-terminal amino acids, tryptic-peptide mapping and CNBr-cleavage products. Both proteins contained significant amounts of sulphur amino acids. The proteins were shown to be located in the soluble cytosol fraction of cotyledon cells and are not significantly degraded on seed germination. Preliminary screening indicates the presence of homologous major albumin proteins in at least three different, though closely related, legume species.     

Induction of somatic embryos in pea,Pisum sativum L.

Using low concentrations of picloram (0.06 mg/l), embryoids were formed on the surface of leaf-derived callus of pea, Pisum sativum L. (c.v. Dippes Gelbe Victoria) upon transfer to liquid medium. After some days in culture, embryoids spontaneously separated from the calli, and developed into torpedo-shaped embryos, which were transferred to solid medium. In a second series of experiments, embryos were also formed by mutant 489C and a genetic line of Pisum arvense, which additionally exhibited embryogenesis also from epicotyl-derived callus. Some of the embryos showed root formation, but no shoot morphogenesis occurred. In a limited number of cases, an additional root was formed in the apparent shoot apical region after 2–5 days.     

The effect of EDTA and EDDS on lead uptake and localization in hydroponically grown Pisum sativum L.

Pisum sativum plants were treated for 3 days with an aqueous solution of 100 μM Pb(NO₃)₂ or with a mixture of lead nitrate and ethylenediaminetetraacetic acid (EDTA) or [S,S]-ethylenediaminedisuccinic acid (EDDS) at equimolar concentrations. Lead decline from the incubation media and its accumulation and localization at the morphological and ultrastructural levels as well as plant growth parameters (root growth, root and shoot dry weight) were estimated after 1 and 3 days of treatment. The tested chelators, especially EDTA, significantly diminished Pb uptake by plants as compared to the lead nitrate-treated material. Simultaneously, EDTA significantly enhanced Pb translocation from roots to shoots. In the presence of both chelates, plant growth parameters remained considerably higher than in the case of uncomplexed Pb. Considerable differences between the tested chelators were visible in Pb localization both at the morphological and ultrastructural level. In Pb+EDTA-treated roots, lead was mainly located in the apical parts, while in Pb+EDDS-exposed material Pb was evenly distributed along the whole root length. Transmission electron microscopy and EDS analysis revealed that in meristematic cells of the roots incubated in Pb+EDTA, large electron-dense lead deposits were located in vacuoles and small granules were rarely noticed in cell walls or cytoplasm, while after Pb+EDDS treatment metal deposits were restricted to the border between plasmalemma and cell wall. Such results imply different ways of transport of those complexed Pb forms.     

The control of damping-off in Pisum sativum L. by cycioheximide

Experiments on the effect of cycioheximide (Acti-dione) in controlling damping-off disease of peas confirmed that phytotoxicity would preclude its use despite its high toxicity to Pythium spp. The antibiotic did not inhibit germination of peas, but retarded growth of the shoot; the tap root was apparently unaffected, but the lateral roots were stunted.     

Endomitosis and the effect of gibberellic acid in different Pisum sativum L. cultivars

The evolution of the total amount of DNA in epicotyls and of the amount of DNA per cell nucleus in epicotyl cortex cells during germination was followed in two closely related pea varieties, Pisum sativum cv. Finale and Pisum sativum cv. Rondo. Under etiolating conditions, growth of the cv. Rondo occurs only by cell elongation which is preceded by endomitotic DNA synthesis, while in the cv. Finale growth is the result of cell elongation accompanied by endomitotic DNA synthesis and cell division. The maximum C-level attained in both cultivars under etiolating conditions is 8 C (C=haploid amount of DNA in a gamete cell). Both the maximum C-level reached and the percentage of cells reaching this C-level seem to be under strict genetic control. In both cultivars, light inhibits the endomitotic DNA replication.Neither gibberellic acid (GA₃), nor AMO 1618 alter the maximum C-level or the percentage distribution of the C-classes. Both growth regulators are effective, although in an opposite way, only in tissues where cell division occurs or where endomitotic DNA synthesis is blocked, as in light-grown pea epicotyls.     

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.     

The Influence of Genes ar and n on Senescence in Pisum sativum L.

The effect of genes ar (violet flowers, small hilum) and n (thick,fleshy pod wall) on whole plant in senescence peas was examinedby comparing Ar- with arar and N- with nn plants in segregatingprogenies. Homozygosity for ar or n significantly delayed the time whenthe plants were ready for harvest of their entire seed crop.These genes did not delay either the onset of reproduction orthe onset of apical arrest in the first instance. However, whereasAr- N- plants almost invariably senesced and died as the firstseed crop matured, the majority of arar and/or nn plants entereda period of secondary growth and a further fruiting cycle. Comparedwith Ar- plants, arar plants had over twice as many pods andseeds but individual seeds were 58 per cent lighter and totalseed yield (wt) was 19 per cent less. Pod length was unaffected.Compared with N-plants, nn plants had shorter pods (16 per cent),fewer seeds per pod (21 per cent), smaller seeds (20 per cent)and a lower total seed yield (wt 14 per cent less). It appearsthat ar and n impose a lower metabolic drain per reproductivenode as a consequence of their effects on hilum anatomy andpod morphology, respectively. These mutants disrupt the normalpattern of monocarpic senescence by breaking the coordinationbetween apical arrest and subsequent events. The developingseed crop delimited by the first arrest fails to cause plantdeath, possibly because sink size is less than in normal counterparts. Pisum sativum L, garden pea, senescence, hilum, pod, seed size, genetics     

Apyrase,streptavidin-binding proteins,and antimicrobial activity in Pisum sativum

The 49 kD apyrase (EC 3.6.1.5), streptavidin-binding proteins, and antimicrobial activity in the subcellular fractions from different seed parts of Pisum sativum L. var. Alaska were examined. Except cotyledons, all subcellular fractions contained 49 kD apyrase, and a considerable relationship was found between 49 kD apyrase and NTPase activities that increased with increasing time of germination. The bulk of 49 kD apyrase and NTPase activities was found in the nucleus pellets and cytoskeleton-enriched fraction, indicating their physiological importance. At 72 h of germination, all subcellular fractions of primary stems have a greater amount of 49 kD apyrase and NTPase than primary leaves and much more than primary roots and cotyledonary stalks. All seed parts showed antimicrobial activities, and the bulk of inhibition activities was found in the cytoskeleton-enriched and nucleus pellets, which was greater in the primary stems and leaves than in other parts. Current findings reveal that apyrases have important roles in metabolic activities in all parts of the pea plants except cotyledons. Cotyledons contained much streptavidin-binding proteins, which might have different physiological roles than apyrases.