Polyhydroxyalkanoate polymers and their production in transgenic plants.

Commercialization of plant-derived polyhydroxyalkanoates will require the creation of transgenic crop plants that possess high product yields, normal plant phenotypes, and transgenes that are stable over several generations. The studies included in this review describe the progress that has been made toward achieving these goals in both model plant systems and commercial crop plants.     

Metabolism of Indole-3-acetaldehyde.

Aerobic infiltration of synthetic indoleacetaldehyde (IAAld) in buffered medium of pH 4.55, into living tissues of lower and higher plants, leads in the majority of cases to the formation of both indoleacetic acid and tryptophol. This activity is evinced by etiolated as well as green tissues. Besides, all parts of higher plants tested — roots, cotyledons, hypocotyls and leaves possess this activity. Abolishment of this activity by boiling indicates its enzymic nature. Coupled with the established occurrence of indoleacetaldehyde, the widespread distribution of such activity, strengthens the probability that indoleacetaldehyde may be the normal and natural precursor in the biosynthesis of indoleacetic acid.     

Spontaneous extensive chromosome elimination in somatic hybrids between somatically congruent species Nicotiana tabacum L. and Atropa belladonna L.

Summary Mesophyll protoplasts of the kanamycin-resistant nightshade, Atropa belladonna, were fused with mesophyll protoplasts of the phosphinothricin resistant-tobacco, Nicotiana tabacum. A total of 447 colonies resistant to both inhibitors was selected. Most of them regenerated shoots with morphology similar to one of the earlier obtained and described symmetric somatic hybrids Nicotiana + Atropa. However, three colonies (0.2%) regenerated vigorously growing tobacco-like shoots; they readily rooted, and after transfer to soil, developed into normal, fertile plants. Unlike their tobacco parental line, BarD, the obtained plants are resistant to kanamycin [they root normally in the presence of kanamycin (200 mg/1)] and possess activity of neomycin phosphotransferase (NPT II) with the same electrophoretic mobility as the one of the nightshade line. According to Southern blot hybridization analysis carried out with the use of radioactively labeled cloned fragments of the Citrus lemon ribosomal DNA repeat, as well as with Nicotiana plumbaginifolia genus-specific, interspersed repeat Inp, the kanamycin-resistant plants under investigation have only species-specific hybridizing bands from tobacco. Cytological analysis of the chromosome sets shows that plants of all three lines possess 48 large chromosomes similar to Nicotiana tabacum ones (2n = 48), and one small extra chromosome (chromosome fragment) similar to Atropa belladonna ones (2n = 72). Available data allow the conclusion that highly asymmetric, normal fertile somatic hybrids with a whole diploid Nicotiana tabacum genome and only part (not more than 2.8%) of an Atropa belladonna genome have been obtained without any pretreatment of a donor genome, although both these species are somatically congruent.     

Stachyose Synthesis in Source Leaf Tissues of the CAM Plant Xerosicyos danguyi H. Humb

Leaf tissues from Xerosicyos danguyi H. Humb., a succulent member of the Cucurbitaceae, were found to possess both galactinol synthase activity and the capacity for photosynthetic production of stachyose, the phloem transport oligosaccharide common to other nonsucculent cucurbits. The amounts of stachyose isolated from leaf tissues, and the extractable activity of galactinol synthase, were somewhat higher in leaf tissues obtained from plants operating in the Crassulacean acid metabolism (CAM) mode (well watered plants) compared to leaf tissues from plants operating in the CAM-idling mode (water-stressed plants). In contrast, in leaf discs, the photosynthetic incorporation of label into stachyose following pulse labeling with ¹⁴CO₂ was similar for stressed and for nonstressed tissues. Stachyose could be extracted from, and was synthesized photosynthetically by, leaf discs which contained no vascular tissues, indicating that synthesis of stachyose can occur in photosynthetic mesophyll cells of Xerosicyos.     

THE RELATIONSHIP BETWEEN THE PRIMARY THICKENING MERISTEM AND THE SECONDARY THICKENING MERISTEM IN YUCCA WHIPPLEI TORR. III. OBSERVATIONS FROM HISTOCHEMISTRY AND AUTORADIOGRAPHY

Observations were made of stem sections stained for RNA and protein of Yucca whipplei ranging from germinated seedlings to 6-month-old plants. One-, two-, and three-month-old plants were labeled with tritiated thymidine, fixed in FAA, sectioned, stained with the Feulgen reaction, and prepared for autoradiography. The serial transverse sections were outlined with a drawing tube recording all labeled nuclei on a computer graphics tablet. Computer-assisted three-dimensional reconstructions were made to observe the locations of labeled nuclei. The two techniques are in agreement: the thickening meristem is broad near the top of the stem, occupies a narrower band at more basipetal levels, and disappears below the level of recent root initiation. There are no gaps in staining or labeling, and there are no changes in staining or labeling that would distinguish between the activities of the primary thickening meristem and the secondary thickening meristem in those plants which possess both. The meristems are continuous at all stages of development in the young vegetative stem. The STM is interpreted to be a developmental continuation of the PTM.     

NUTRITIONAL STUDIES OF TWO RED ALGAE. I. GROWT RATE AS A FUNCTION OF NITROGEN SOURCE AND CONCENTRATION1

Gracilaria foliifera (Forsskal) Borgesen and Neoagardhiella bailiyi (Harvey ex Kiitzing) Wynne & Taylor were grown in continuous-flow culture under controlled environmental conditions in 15 liter experimental chambers. Growth rate was related to the source and concentration of nitrogen enrichment supplied to the plants, Growth rate appeared to follow saturation-type nutrient uptake kinetics for plants receiving ammonium, nitrate, urea of sewage effluent enrichments. Ammonium enrichment produced higher growth rates than nitrate of sewage enrichment. The lowest growth rates occurred in the chambers receiving unenriched seawater or urea. The low estimated constants (K) for growth were in the range of 0.2–0.4 (M N for all N enrichments examined. The low estimated values of K compare closely with those found for microalgae and indicate that both species possess the ability to utilize very low concentrations of N.     

Preliminary evaluation of anti-inflammatory and anti-arthritic activity of S. lappa, A. speciosa and A. aspera.

Saussurea lappa, Argyreia speciosa and Achyranthes aspera are well known Indian medicinal plants used in the indigenous systems of medicine for the treatment of inflammatory conditions. The ethanolic extracts of the plants at the doses of 50, 100 and 200 mg/kg, p.o. were screened for their effect on acute and chronic inflammation induced in mice and rats. S. lappa and A. speciosa were found to significantly inhibit paw edema induced by carrageenan and Freund's complete adjuvant and to prevent accumulation of inflammatory cells in carrageenan-induced peritonitis at doses of 50-200 mg/kg. A. aspera inhibited these inflammatory responses at doses of 100-200 mg/kg. The studies reveal that the ethanolic extracts of S. lappa, A. speciosa and A. aspera possess anti-inflammatory and anti-arthritic activity and support the rationale behind the traditional use of these plants in inflammatory conditions.     

Some characteristics of Pseudomonas syringae pv. maculicola dissociants

Pseudomonas syringae pv. maculicola dissociants producing colonies of different morphotype were found to possess similar biochemical and serological properties but different virulence to the host plant. The heterogeneous extracellular and intracellular lipopolysaccharide-protein complexes of the dissociants differed in their chemical composition and biological activity towards test plants.     

激活Raji细胞EB病毒早期抗原植物的研究

以前材料证明Raji细胞EB病毒早期抗原对于诊断鼻咽癌有很高的特异性。我们研究了1693种植物,试验发现52种植物具有激活EB病毒作用。本文报道了这些植物并讨论它们与鼻咽癌关系。     

Scheel D. and Wasternack C.(eds) Plant Signal Transduction.

The recent whole-scale sequencing of several organisms has revealedtwo surprising facts to me. Firstly, I as a human with considerablepride in the genetic complexity controlling my differentiation,my immune response, my memory and my behaviour, really do nothave so many more genes compared to plants. Secondly, when surveyingthe genomes of mammals, flies and worms, I found about 50 receptorkinase genes per genome, whereas plants possess about 400. Whatare all the receptors doing in     

Interspecific hybridization between Brassica juncea and B. spinescens through protoplast fusion

Hypocotyl derived protoplasts of B. juncea cv. RLM-198 were fused with mesophyll protoplasts of B. spinescens using polyethylene glycol to produce interspecific hybrids. Fusion products could be microscopically identified by characteristics of the protoplasts of both parents in the hybrid cells; they are colourless and vacuolated like the hypocotyl protoplasts and possess chloroplasts of the mesophyll protoplasts. The heterokaryotic fusion frequency was around 5%. However, the frequency of calli regenerating hybrid shoots was more than 10% of the regenerating calli. Putative somatic hybrids had morphological features characteristic of both the parents. Twelve plants analysed cytologically, possessed 52 chromosomes (26_II) at meiosis representing the complete genomes of B. juncea (18_II) and B. spinescens (8_II). For esterase isozymes, the hybrids had bands of Doth the parents. Hybrid nature of some of the plants was confirmed by their close resemblance to B. juncea, chromosome number and isozyme bands of B. spinescens as in Rsp-19. Somatic hybrids had rudimentary, non-dehiscent anthers and completely sterile pollen. However, on back crossing with B. juncea, 10 out of 12 plants produced seeds and about 100 plants were realized.Abbreviations PEG Polyethylene glycol     

Some Characteristics of Pseudomonas syringae pv. maculicola Dissociants

Pseudomonas syringae pv. maculicola dissociants producing colonies of different morphotypes were found to possess similar biochemical and serological properties but different virulence to the host plant. The heterogeneous extracellular and intracellular lipopolysaccharide–protein complexes of the dissociants differed in their chemical composition and biological activity towards test plants.     

Detection of selection in populations of white clover (Trifolium repens L.)

Seed populations of white clover polymorphic for the presence/absence of both ovariogenic glucosides and the hydrolysing enzyme linamarase, were introduced into three natural populations. Over the first six months of life a significant increase in the frequency of linamarase containing individuals occurred. Estimated selection coefficients against plants lacking linamarase were in the region of 0.3. This result may have been due to selection at the enzyme locus alone, or to selection favouring cyanogenic individuals which possess both cyanogenic glucosides and enzyme.     

Evidence for a cyclic diguanylic acid-dependent cellulose synthase in plants.

Because numerous attempts to detect an activity for a cellulose synthase in plants have failed, we have taken a different approach toward detecting polypeptides involved in this process. The uniqueness of the structure and function of cyclic diguanylic acid (c-di-GMP) as an activator of the cellulose synthase of the bacterium Acetobacter xylinum makes it an attractive probe to use in a search for a c-di-GMP receptor that might be involved in the process in plants. Direct photolabeling with 32P-c-di-GMP has been used, therefore, to identify in plants two membrane polypeptides of 83 and 48 kD derived from cotton fibers that possess properties consistent with their being components of a c-di-GMP-dependent cellulose synthase. Based upon several criteria, the 48-kD species is proposed to be derived by proteolytic cleavage of the 83-kD polypeptide. Both polypeptides bind c-di-GMP with high affinity and specificity and show antigenic relatedness to the bacterial cellulose synthase, and the N-terminal sequence of the 48-kD polypeptide also indicates relatedness to the bacterial synthase. Ability to detect both cotton fiber polypeptides by photolabeling increases markedly in extracts derived from fibers entering the active phase of secondary wall cellulose synthesis. These results provide a basis for future work aimed at identifying and characterizing genes involved in cellulose synthesis in plants.     

The two analogous phosphoglycerate mutases of Escherichia coli.

The glycolytic enzyme phosphoglycerate mutase exists in two evolutionarily unrelated forms. Vertebrates have only the 2,3-bisphosphoglycerate-dependent enzyme (dPGM), whilst higher plants have only the cofactor-independent enzyme (iPGM). Certain eubacteria possess genes encoding both enzymes, and their respective metabolic roles and activities are unclear. We have over-expressed, purified and characterised the two PGMs of Escherichia coli. Both are expressed at high levels, but dPGM has a 10-fold higher specific activity than iPGM. Differential inhibition by vanadate was observed. The presence of an integral manganese ion in iPGM was confirmed by EPR spectroscopy.     

Alterations in some oxidative parameters in susceptible and resistant wheat plants infected with Puccinia recondita f.sp. tritici

We studied the systemic effects after infection of susceptible and resistant (expressing HSR) wheat plants with leaf rust (Puccinia recondita f.sp. tritici) on the amount of hydrogen peroxide and activity of some ROS scavenging enzymes. Measurements were performed 7 and 21 days after inoculation. In susceptible cultivar (Sadovo 1), an inhibition of activity of catatase and GST was found. By contrast, in resistant cultivar (Kristal), the infection caused an activation of these enzymes. Moreover, it was established that cv. Kristal plants possess constitutive higher levels of hydrogen peroxide, as well as higher superoxide dismutase activity.     

The effect of the Agrobacterium tumefaciens attR mutation on attachment and root colonization differs between legumes and other dicots

Infections of wound sites on dicot plants by Agrobacterium tumefaciens result in the formation of crown gall tumors. An early step in tumor formation is bacterial attachment to the plant cells. AttR mutants failed to attach to wound sites of both legumes and nonlegumes and were avirulent on both groups of plants. AttR mutants also failed to attach to the root epidermis and root hairs of nonlegumes and had a markedly reduced ability to colonize the roots of these plants. However, AttR mutants were able to attach to the root epidermis and root hairs of alfalfa, garden bean, and pea. The mutant showed little reduction in its ability to colonize these roots. Thus, A. tumefaciens appears to possess two systems for binding to plant cells. One system is AttR dependent and is required for virulence on all of the plants tested and for colonization of the roots of all of the plants tested except legumes. Attachment to root hairs through this system can be blocked by the acetylated capsular polysaccharide. The second system is AttR independent, is not inhibited by the acetylated capsular polysaccharide, and allows the bacteria to bind to the roots of legumes.     

Study on the chemical composition and antioxidant activity of extracts from shoot culture and regenerated plants of <Emphasis Type="Italic">Scutellaria altissima</Emphasis> L.

The flavonoid (baicalin, wogonoside, luteolin, luteolin-7-glucoside) and verbascoside contents of Scutellaria altissima in both shoot cultures, and the shoots and roots of micropropagated plants grown in the greenhouse for 12 weeks or in the field for 2 years were determined. The level of secondary metabolites was found to be strongly affected by the age and type of plant organ. A comparative analysis of S. altissima plants propagated in vitro and from seeds revealed no differences in the level of secondary metabolites when plants of the same age were studied. The antioxidant potential of methanolic extracts from shoot cultures, and the shoots and roots of S. altissima plants propagated in vitro, were evaluated using ABTS radical scavenging, FRAP metal reduction power and the lipid peroxidation test, in relation to the content of baicalin, wogonoside, verbascoside, total phenolic and total flavonoid compounds. Extracts from the roots of field-grown regenerated plants at the flowering stage were found to possess the strongest antioxidant activity. Correlation analysis revealed that the antioxidant activity of extracts correlated most closely with their total phenolic content estimated by the Folin-Ciocalteu method.     

Distribution of style and pollen polygalacturonases among distylous and homostylous Turnera and Piriqueta spp. (Turneraceae)

We explore the distribution of a style and pollen polygalacturonase in a number of distylous and homostylous species of Turnera, and two species of Piriqueta (Turneraceae). We show, using immunoblotting with antibodies made against these proteins, that the style polygalacturonase is specific to styles of short-styled plants of all the six distylous species of Turnera we have investigated. Styles of a somatic homostylous mutant derived from a short-styled plant do not possess the style polygalacturonase. Distylous P. caroliniana did not appear to possess this protein. We show that the pollen polygalacturonase, while associated with the short-styled morph in three species, is polymorphic among short-styled plants of T. krapovickasii, and absent from T. joelii, T. grandiflora and P. caroliniana. These data support a role for the style polygalacturonase in distyly, possibly in the incompatibility system, but cast doubt on any role for the pollen polygalacturonase. In concert with the predictions for the mode of origin, and the response of styles of homostylous species to pollen from long- and short-styled plants, we find that none of the homostylous species possess the style polygalacturonase. The pollen polygalacturonase does occur in some homostylous species, but not in others. It is not clear that the pollen polygalacturonase, however, provides a marker for the mode of origin of homostyly.     

Some properties of methylotrophic bacteria isolated from sewage sludges derived from mechanical and biological sewage treatment plants.

The presented studies were carried out to get more information about physiological properties of methylotrophic bacteria selected from sewage sludges derived from mechanical and biological sewage treatment plants. All the isolated bacterial strains belonged to facultative methylotrophs. The majority of them utilized glucose, starch and lipids. Moreover, most of them were also found to possess proteolytic properties and were able to hydrolyze urea but they were incapable of asparagine ammonification.