bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of preliminary heat‐shock treatment on accumulation of osmolytes and drought resistance in cotton plants during water deficiency
Authors: Kuznetsov Vladimir V. , Rakitin Viktor YU. , Zholkevich Vladimir N.
Published: March 2003

To elucidate how plants adapt to overheating followed by water deficiency, experiments with two cotton (Gossypium hirsutum L.) cultivars (Ok‐oltin and INEBR‐85) were performed. Preliminary heat‐shock (HS) treatment (45°C for 1.5 h) increased resistance of both cultivars to subsequent progressive soil drought [40 days without watering, with soil moisture gradually decreasing from 70 to 20% of field moisture capacity (FMC)]. HS induced accumulation of amino acids and amides and increased their contribution to the osmotic pressure (OP) of the leaf cell sap. HS also enhanced resistance to water deficiency and to overheating of the leaves, especially in cv. INEBR‐85, the more drought resistant of the two cultivars. The results suggest the existence of common resistance systems to both stress factors, in particular, accumulation of amino acids and amides (mainly arginine, proline and asparagine) – their concentration in the cell sap increased up to 240‐, 160‐ and 150‐fold, respectively.
Penetration of UV‐A, UV‐B and blue light through the leaf trichome layers of two xeromorphic plants, olive and oak, measured by optical fibre microprobes
Authors: Karabourniotis George , Bornman Janet F.
Published: March 2003

Quartz fibre‐optic microprobes were used to monitor the light microenvironment beneath trichome layers of the xeromorphic leaves of two Mediterranean evergreen sclerophylls, Olea europaea and Quercus ilex. Young developing leaves of both plants were densely pubescent on both surfaces of the lamina, whereas the mature leaves were pubescent only on the abaxial side. Trichome layers of young as well as of mature leaves of both plants attenuated almost all incident ultraviolet (UV)‐B (310 nm) and UV‐A (360 nm) radiation and a considerable portion of blue light (430 nm). Abaxial trichome layers of young leaves were more effective in screening out the incident radiation compared to the adaxial ones of the same leaves and also compared to the abaxial layer of the mature leaves. The abaxial epidermis of dehaired mature leaves of O. europaea was ineffective in absorbing most of the incident UV‐B and UV‐A radiation. UV and visible spectra beneath trichome layers of O. europaea in mature leaves confirmed that the light microenvironment on the epidermis was deprived in the UV‐B, UV‐A and partly in the blue spectral regions. It is proposed that the occurrence of a dense trichome layer, especially in young leaves, may play a protective role against not only UV‐B radiation damage, but also against high visible irradiance. This function is performed irrespective of the differing anatomy of individual hairs of both plants. The protection provided by the trichomes could afford advantages under stress conditions, especially during leaf development.
Photosynthetic activity of developing leaves of Zea mays is less affected by heat stress than that of developed leaves
Authors: Karim MD. Abdul , Fracheboud Yvan , Stamp Peter
Published: March 2003

Various physiological and biochemical characters of a leaf change with stages of its ontogeny. It is likely that the photosynthetic functions of leaves of different ontogeny have different levels of heat tolerance. This study was initiated to analyze the photosynthetic heat tolerance of fully‐developed, nearly‐developed (more than 2/3 expanded) and developing (10–12 cm visible) leaves of two maize genotypes, F223 and F250. The results indicate that the photosynthetic CO2 assimilation rate (Pn) of developing leaves was less affected by heat stress (42°C in the dark for 90 min) than that of developed leaves. The impaired Pn recovered within 24 h in the developing leaves, while the Pn of developed and nearly‐developed leaves did not reach the non‐stress level, even after 72 h. The Pn of the developed leaves of genotype F250 was less affected by heat stress than that of genotype F223. After heat stress, the slightly affected Pn of the developing leaf was associated with the almost unchanged photochemical efficiency of photosystem II (Fv/Fm) and the quantum yield of photosystem II electron transport. The chlorophylls a and b were degraded by heat stress; the degradation was pronounced in the developed leaves. As a result of heat stress, the antheraxanthin and zeaxanthin of the xanthophyll cycle accumulated in both the nearly‐developed and developed leaves but not in the developing leaves. Injury to the plasma membrane due to heat stress was much less severe in developing leaves than that in the developed leaves. From the physiological characters which we determined it would appear that the Pn functions of the developing leaves are more resistant to heat stress than those of nearly‐developed and developed leaves.
Induction of a proteinase K inhibitor in a potato cultivar with a high degree of field resistance against Phytophthora infestans
Authors: Feldman Mariana L. , Oliva Claudia R. , Casalongué Claudia A. , Daleo Gustavo R.
Published: March 2003

A proteinase K inhibitor (PLPKI) was isolated from a potato cultivar with a high level of field resistance (Solanum tuberosum L. cv. Pampeana INTA), after 24 h of infection with Phytophthora infestans, when inhibitory activity was markedly increased. Purification was performed by heat treatment, gel filtration chromatography and affinity chromatography. A size of 60 kDa was estimated by SDS‐PAGE in partially denaturing conditions and by gel filtration. It is multimeric and the monomer has a molecular mass of 8.5–9.0 kDa. PLPKI is highly active against proteinase K (EC 3.4.21.14) but poorly inhibits two serine proteinases of animal origin, trypsin (EC 3.4.21.4) and chymotrypsin (EC 3.4.21.1). A differential expression (determined by activity and immunoblotting assays) of PLPKI was observed between two potato cultivars with different degrees of field resistance to P. infestans. In the resistant cultivar (cv. Pampeana INTA) PLPKI induction (19‐fold with respect to healthy leaves) occurred 24 h after infection and remained over basal levels after 48 h infection. By contrast, in the susceptible cultivar (cv. Bintje), no induction was observed.
Characterization of a protease that acts specifically on the 22‐kDa protein in thylakoid membranes from green spores of the fern Osmunda japonica
Authors: Inoue Hiroshi , Kamachi Hiroyuki , Yamaya Daigo , Oguma Miwa , Noguchi Munenori
Published: March 2003

A proteolytic enzyme responsible for the breakdown of a 22‐kDa protein, whose abundance decreases in thylakoid membranes during germination of green spores of the fern Osmunda japonica, was partially purified from the thylakoid membranes of quiescent spores by a combination of ammonium sulfate fractionation, ion‐exchange chromatography on DEAE‐Toyopearl 650 S and size‐fractionation HPLC on G3000SW. The enzyme was found to be a cysteine endoproteinase, as judged by its dependency on sulfhydryl reagents and inhibition by E‐64 and iodoacetate, and by the appearance of distinct proteolytic products that were not further degraded during prolonged reaction time. Highest protease activity was observed around pH 9.7, the activity being partially suppressed by cations. The Km of the 22‐kDa protein as a substrate in the proteolysis was 67 μg ml−1, equivalent to 3 μM. The enzyme, with a native molecular mass of about 43 kDa, showed high specificity against the 22‐kDa protein as a substrate. The isolated protease could not degrade the 22‐kDa protein associated with fresh thylakoid membranes but digested the protein in the presence of 0.05% Triton X‐100.
Immunopurification of H+‐ATPase‐containing lipid‐protein particles from the cytosol of carnation petals
Authors: Hudak K. A. , Madey E. , Hong Y. , Su L. , Thompson J. E.
Published: March 2003

Lipid‐protein particles originating from the plasma membrane were immunopurified from the cytosol of carnation petal cells (Dianthus caryophyllus L. cv. Improved White Sim) using antibodies raised against the central hydrophilic domain of the H+‐ATPase. The immunopurified particles are enriched in lipid metabolites, in particular free fatty acids and steryl/wax esters, by comparison with corresponding microsomal membranes, and the lipids of the particles are more saturated than those of microsomal membranes. Proteolytic catabolites of the H+‐ATPase, a protein associated with the plasma membrane, but not the native H+‐ATPase protein, are also present in the immunopurified cytosolic particles. Osmiophilic particles were discernible in the cytosol of carnation petal cells by transmission electron microscopy, and the association of H+‐ATPase catabolites with a subpopulation of these particles was confirmed by immunogold labelling with H+‐ATPase antiserum. Cross‐reaction of the H+‐ATPase antiserum with elements of the cytosol was also evident by immunofluorescent light microscopy. These observations collectively indicate that lipid‐protein particles of plasma membrane origin are present in the cytosol of carnation petal cells and that their formation may serve as a means of removing lipid and protein metabolites from the plasma membrane which would otherwise destabilize its structure.
Sucrose/cytokinin interaction in Sinapis alba at floral induction: a shoot‐to‐root‐to‐shoot physiological loop
Authors: Havelange Andrée , Lejeune Pierre , Bernier Georges
Published: March 2003

In plants of Sinapis alba induced to flower by exposure to a single long day (LD), previous work demonstrated that the movement of a shoot‐to‐root signal early during the photoextension period of the LD was essential for flowering. Interrupting this movement by bark ringing (girdling) of the stem inhibited the floral response of plants to the LD. In the present work we show that (a) the girdling treatment decreases the soluble sugar level in the roots of induced plants, and (b) the inhibitory effect on the floral response caused by girdling can be completely overcome by supplying the roots with sucrose directly at appropriate times. Thus, we demonstrate that sucrose moving in the phloem is the shoot‐to‐root signal essential for flowering. We have also found that one of the major effects of the extra‐sucrose on the roots is to stimulate the root‐to‐shoot movement of [9R]Z, the predominant cytokinin of the xylem sap in Sinapis. The importance of this upward movement of [9R]Z for flowering is indicated by the observation that (a) the floral response to the LD is inhibited by growing plants in an atmosphere saturated with water (impairing upward movement of xylem sap) during the LD itself, and (b) the inhibitory effect on the floral response caused by girdling, which markedly reduces [9R]Z export from roots, is relieved by direct application of BA, a cytokinin, to the apex. Other possible effects of the shoot‐derived sucrose on roots in relation to flowering are also discussed. Our results show that a shoot‐to‐root‐to‐shoot physiological loop is essential for flowering in intact Sinapis plants.
High resistance to low‐temperature photoinhibition in two alpine, snowbank species
Authors: Germino Matthew J. , Smith William K.
Published: March 2003

At high elevation, the combination of low temperature and high solar irradiance may be particularly conducive to the low‐temperature photoinhibition of photosynthesis (LTP). Microclimate and photosynthesis were measured in situ in Caltha leptosepala and Erythronium grandiflorum, alpine perennials that may experience even lower temperatures and higher sunlight (PFD, photon flux density) than other alpine plants due to their proximity to snowbanks. Light‐saturated CO2 assimilation (Asat) and chlorophyll a fluorescence were measured for naturally frosted and non‐frosted plants that also experienced either natural or experimentally‐lowered sunlight. Following several hours of full sunlight exposure, Asat in both species was not different in leaves that experienced either frostless nights, shading (ca. 1200 versus 2000 μmol m−2 s−1 PFD), or the combination of frostless nights and shade, compared to leaves that experienced frost followed by full sunlight. However, increases in the maximum efficiency of photosystem II photochemistry occurred following either frostless nights (change in Fv/Fm=5.3%; P<0.001), experimental shade (4.0%; P<0.1), or the combination of frostless nights and shade (8.4%; P<0.001) in C. leptosepala. Corresponding increases in Fv/Fm were less in E. grandiflorum (1.8% following frostless nights, P<0.05; 3.7% with shade, P<0.05; and 5.1% with both, P<0.001). Plants of E. grandiflorum in the process of emerging through snowbanks had a 10% increase in Fv/Fm with experimental shading (P<0.05). In both species, depressions in Fv/Fm that resulted from natural frost and high sunlight exposure recovered fully by sunset the same day, and depressed Fv/Fm was associated with greater non‐photochemical quenching. Thus, only slight and reversible LTP was apparent, and both species appeared well‐adapted for maintaining carbon gain on days following frost and high sunlight exposure.
Degradation of lysine in rice seeds: Effect of calcium, ionic strength, S‐adenosylmethionine and S‐2‐aminoethyl‐	l‐cysteine on the lysine 2‐oxoglutarate reductase‐saccharopine dehydrogenase bifunctional enzyme
Authors: Gaziola S. A. , Sodek L. , Arruda P. , Lea P. J. , Azevedo R. A.
Published: March 2003

Lysine biosynthesis has been extensively studied and the regulatory enzymes characterized in some of the most important crop plants, however, much less is known about the lysine degradation pathway. Lysine 2‐oxoglutarate reductase (LOR) and saccharopine dehydrogenase (SDH) have recently been partially purified and characterized from plants, and have been shown to exist as a single bifunctional polypeptide. We have further characterized these enzymes from rice endosperm in relation to Ca2+ and ionic strength modulation. Optimum pH values of 7.0 and 8.0 were obtained for LOR and SDH, respectively. The LOR domain of the polypeptide was modulated by Ca2+ and ionic strength, whereas the SDH domain was not. It would appear that the modulation by Ca2+ and ionic strength of LOR is a common feature among plant LOR enzymes. S‐adenosylmethionine (SAM) did not produce any significant effect on either enzyme activity, indicating that it only plays a role in the regulation of lysine biosynthesis. The effect of S‐2‐aminoethyl‐
l‐cysteine (AEC) as both a substrate and an inhibitor of LOR activity was also tested. AEC was shown to partially substitute for lysine as a substrate for LOR, but was also able to inhibit LOR activity, possibly competing with lysine at the active site. The higher Km for AEC compared to lysine may reflect a lower binding affinity for AEC.
Induction of oxidative stress and GPX‐like protein activation in tomato plants after mechanical stimulation
Authors: Depège Nathalie , Varenne Michèle , Boyer Nicole
Published: March 2003

In Lycopersicon esculentum Mill. (cv. VFN8), mechanical stimulation induced a rapid and transient increase of with hydrogen peroxide (H2O2), a part of an oxidative burst. The reaction was followed by an antioxidative response, with the involvement of phospholipid hydroperoxide glutathione peroxidase (PHGPX)‐like protein (EC 1.11.1.9). Induction of expression of two putative PHGPX genes was observed in rubbed internodes. To characterize the importance of this antioxidant gene, enzymatic activities of glutathione peroxidase (GPX) and PHGPX were measured, respectively, H2O2 and hydroperoxide lipid as oxidant. Only PHGPX activities were induced by the mechanical treatment, suggesting a major role of PHGPX in the mechanisms of antioxidant defence in plant.
Growth rate and biomass partitioning of wildtype and low‐gibberellin tomato (Solanum lycopersicum) plants growing at a high and low nitrogen supply
Authors: Nagel Oscar W. , Konings Henk , Lambers Hans
Published: March 2003

The growth‐promoting effects of gibberellins (GAs) on plants are well documented, but a complete growth analysis at the whole plant level on plants with an altered GA biosynthesis has never been reported. In the present work, the relative growth rate (RGR), biomass partitioning and morphological parameters of wildtype (Wt) tomato (Solanum lycopersicum L. cv. Moneymaker) plants were compared with those of isogenic (gib) mutants with a reduced biosynthesis of gibberellins. GA deficiency reduced RGR and specific leaf area (SLA, leaf area per unit leaf mass) and increased the net assimilation rate (NAR, the rate of biomass increment per unit leaf area). Despite the free access to nitrogen in the rooting medium, the low‐GA mutants had a much higher root mass ratio (RMR, the root mass per unit plant biomass) than the Wt, suggesting that the mutants were disturbed in their growth response to nitrate supply. The experiment was repeated at a low exponential nitrate supply, which forced all plants to grow at the same low RGR. The persistence of the differences in RMR at low N‐supply indicated that the high RMR of the mutants was a direct effect of low GA, which was independent of nitrate supply. Because the low N‐supply increased the RMRs of all genotypes to the same extent, the response of RMR to N‐supply does not seem to depend on GA. Although many of the traits of the slow growing GA mutants were very similar to those of inherently slow growing plant species from unproductive habitats, gibberellins are unlikely to be a main determinant of a plant's potential RGR.
Purine and pyrimidine metabolism during the partial drying treatment of white spruce (Picea glauca) somatic embryos
Authors: Stasolla Claudio , Loukanina Natalia , Ashihara Hiroshi , Yeung Edward C. , Thorpe Trevor A.
Published: March 2003

The imposition of a partial drying treatment (PDT) on mature white spruce somatic embryos is a necessary step for successful germination and embryo conversion into plantlets. Purine and pyrimidine metabolism was investigated during the PDT of white spruce somatic embryos by following the metabolic fate of 14C‐labeled adenine, adenosine, and inosine, as purine intermediates, and orotic acid, uridine, and uracil, as pyrimidine intermediates, as well as examining the activities of key enzymes. Both the salvage and the degradation pathways of purines were operative in partially dried embryos. Adenine and adenosine were extensively salvaged by the enzymes adenine phosphoribosyltransferase and adenosine kinase, respectively. The activity of the former enzyme increased during the PDT. In both mature and partially dried embryos, a large proportion of inosine was recovered as degradation products. The de novo pathway of pyrimidine nucleotide biosynthesis, estimated by the incorporation of orotic acid into the nucleotides and nucleic acids, was high at the end of the maturation period and declined during the PDT. Uridine was the main substrate for the pyrimidine salvage pathway, since a large proportion of uracil was recovered as degradation products, i.e. CO2 and β‐ureidopropionic acid in both mature and partially dried embryos. Uridine was mainly salvaged by uridine kinase, whose activity was found to increase during the PDT. Taken together these results indicate that the PDT might be required for increasing the activity of adenine and uridine salvage enzymes, which could contribute to the enlargement of the nucleotide pool required at the onset of germination.
Characterisation of the assembly pathway of the pea NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR), with emphasis on the role of its substrate, Pchlide
Authors: Aronsson Henrik , Sundqvist Christer , Timko Michael P. , Dahlin Clas
Published: March 2003

The homologous import and membrane association of a key enzyme for chlorophyll biosynthesis, the NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR, EC 1.6.99.1) into pea chloroplasts was investigated in vitro. The co‐factor, NADPH, decreased binding of the precursor protein (pPOR) to the envelope membranes in the presence of ATP. The decrease of the binding reaction with NADPH was not observed with the precursor of the small subunit of Rubisco (pSS).  To investigate possible substrate‐dependency for the import reaction, internal Pchlide concentrations in the plastids were raised by either an addition of δ‐aminolevulinic acid to isolated plastids or etiolation of the seedlings prior to plastid isolation. Increased amounts of plastid‐bound Pchlide gave no observable differences in POR import.  The capacity of POR and 11 different POR mutants, carrying charged‐to‐alanine scanning substitutions, to form a catalytically active POR‐Pchlide‐NADPH complex and to associate with the thylakoid membranes in a protease‐resistant way were tested. Wild‐type POR, as well as the mutants with charge substitutions in the N‐terminal region of the protein, exhibited higher catalytic activity than the POR mutants carrying substitutions in the C‐terminal region. Formation of a catalytically active complex did not, however, increase the association efficiency onto the thylakoids. We can, therefore, postulate that the import of pea POR into pea chloroplasts was not substrate‐dependent, nor did formation of catalytically active complexes stimulate or inhibit the membrane association reaction of POR.
Nitrate reduction in tendrils of semi‐leafless pea
Authors: González Esther M. , Cabrerizo Pablo M. , Royuela Mercedes , Aparicio‐Tejo Pedro M. , Arrese‐Igor Cesar
Published: March 2003

The recessive gene af produces a modification of Pisum sativum L. leaf morphology, where leaflets are replaced by tendrils. Previous reports have suggested that tendrils may contribute to plant growth in a similar way to flat leaf structures, but these reports have been restricted to carbon metabolism. In this work, we investigate the nitrate reduction (nitrate reductase activity) capacity of tendrils of a semi‐leafless variety, Solara, in relation to other leaf structures. Maximum nitrate reductase activity (EC 1.6.6.1), expressed on a protein basis, was significantly lower in tendrils compared to flat structures. However, the activation state of nitrate reductase was significantly higher in tendrils, reaching 70%, compared to flat leaf structures. According to these results, tendrils contributed up to 25% of the overall plant nitrate reduction in the semi‐leafless variety. This figure was even higher when nitrate reduction was calculated from in vivo measurements. The results are discussed in relation to nitrate, magnesium, carbohydrates, amino acids and adenylate levels of tendrils.
Caffeoyl‐coenzyme A 3‐O‐methyltransferase enzyme activity, protein and transcript accumulation in flax (Linum usitatissimum) stem during development
Authors: Day Arnaud , Dehorter Bertrand , Neutelings Godfrey , Czeszak Xavier , Chabbert Brigitte , Belingheri Lionel , David Hélène
Published: March 2003

Flax (Linum usitatissimum) is a commercially important fiber crop in Europe. Lignification of its phloem fibers, although weak, causes a decrease in their commercial quality. In flax, fiber lignin mainly consists of guaiacyl (G) units in contrast to the mixed guaiacyl‐syringyl (G‐S) lignin type occurring in xylem fibers. G lignins are reported as more condensed polymers due to a higher frequency of 5‐5 linkages, whereas the deposition of syringyl end groups in lignins increases the proportion of alky‐aryl ether linkages as β‐O‐4‐bonds. The type of linkages within a lignin polymer depends on the methylation of either the 3‐hydroxyl groups or both 3‐OH and 5‐OH groups, which is controlled by two enzymes: caffeate 3‐O‐methyltransferase (COMT) and caffeoyl‐coenzyme A 3‐O‐methyltransferase (CCoAOMT). First, we measured the in vitro activity of both OMTs in the flax stem tissues during stem development. CCoAOMT activity varied in the same way as COMT, i.e. increased gradually with stem maturity, from the top to the bottom of the stem, was maximum at the flowering stage and was lower, but still scorable, in the outer fiber‐bearing tissues than in the xylem cells. In a second step, we focused our studies on the characterization of CCoAOMT in order to understand the implication of this enzyme in the lignification of flax fiber cells. CCoAOMT activity appeared to be associated with the accumulation of an acidic 33‐kDa polypeptide identified as a CCoAOMT after immunological cross‐reactivity with a poplar CCoAOMT and microsequencing. The differential accumulation of the CCoAOMT protein was confirmed by immunolocalization on tissue prints and correlated with that of the transcripts, suggesting a transcriptional regulation of CCoAOMT in the flax stem.
Overlapping expression of cytosolic glutamine synthetase and phenylalanine ammonia‐lyase in immature leaf blades of rice
Authors: Sakurai Nozomu , Katayama Yoshihiro , Yamaya Tomoyuki
Published: March 2003

In order to estimate whether cytosolic glutamine synthetase (GS1; EC 6.3.1.2) is partly coupled to the reaction of phenylalanine ammonia‐lyase (PAL; EC 4.3.1.5) in developing organs of rice (Oryza sativa L.), we compared the expression pattern of transcripts and proteins for GS1 and PAL in the tissue sections from leaf blades at various stages of development. In immature vascular bundles of unexpanded leaf blades, GS1 mRNA was mainly detected in xylem parenchyma cells, mestome‐sheath cells, and sclerenchyma cells. PAL transcripts were also accumulated in these cell types. Vascular bundles in midribs of immature leaf blades contained mRNAs and proteins for both GS1 and PAL abundantly in sclerenchyma cells, although distribution of these two proteins was not completely overlapped. In immature vascular bundles in midribs, lignin deposition was observed in cell walls of xylem parenchyma cells, mestome‐sheath cells and sclerenchyma cells. These results implied that a part of GS1 in unexpanded leaf blades is possibly involved in reassimilation of ammonia released from PAL reaction during the lignin production.
Isolation and characterization of six peach cDNAs encoding key proteins in organic acid metabolism and solute accumulation: involvement in regulating peach fruit acidity
Authors: Etienne Christelle , Moing Annick , Dirlewanger Elisabeth , Raymond Philippe , Monet René , Rothan Christophe
Published: March 2003

As in many other fleshy fruits, the predominant organic acids in ripe peach (Prunus persica (L.) Batsch) fruit are malic and citric acids. The accumulation of these metabolites in fruit flesh is regulated during fruit development. Six peach fruit‐related genes implicated in organic acid metabolism (mitochondrial citrate synthase; cytosolic NAD‐dependent malate dehydrogenase, and cytosolic NADP‐dependent isocitrate dehydrogenase) and storage (vacuolar proton translocating pumps: one vacuolar H+‐ATPase, and two vacuolar H+‐pyrophosphatases) were cloned. Five of these peach genes were homologous to genes isolated from fruit in other fleshy fruit species. Phylogenetic and expression analyses suggested the existence of a particular vacuolar pyrophosphatase highly expressed in fruit. The sixth gene was the first cytosolic NAD‐dependent malate dehydrogenase gene isolated from fruit. Gene expression was studied during the fruit development of two peach cultivars, a normal‐acid (Fantasia) and a low‐acid (Jalousia) cultivar. The overall expression patterns of the organic acid‐related genes appeared strikingly similar for the two cultivars. The genes involved in organic acid metabolism showed a stronger expression in ripening fruit than during the earlier phases of development, but their expression patterns were not necessarily correlated with the changes in organic acid contents. The tonoplast proton pumps showed a biphasic expression pattern more consistent with the patterns of organic acid accumulation, and the tonoplast pyrophosphatases were more highly expressed in the fruit of the low‐acid cultivar during the second rapid growth phase of the fruit.
Effect of drought and high solar radiation on 1‐aminocyclopropane‐1‐carboxylic acid and abscisic acid concentrations in Rosmarinus officinalis plants
Authors: Munné‐Bosch Sergi , López‐Carbonell Marta , Alegre Leonor , Van Onckelen Harry A.
Published: March 2003

The endogenous concentrations of ACC and ABA were measured, at predawn and at maximum solar radiation, during a summer drought, and recovery after autumn rainfalls, in rosemary (Rosmarinus officinalis L.), a drought‐tolerant species, growing under Mediterranean field conditions. During the summer, plants were subjected to both water deficit and high solar radiation. Plants showed severe reductions in shoot water potential to −3 MPa, which were associated with drastic stomatal closure (73%), a decrease in net photosynthesis, reaching almost zero, and a severe chlorophyll loss (74%). Despite the severity of the stress, plants recovered after the autumn rainfalls. The concentration of ACC was not enhanced by drought, and at predawn these concentrations remained constant at approximately 600 pmol ACC−1 DW throughout the experiment. Thus, ethylene did not regulate the response of rosemary to drought. However, a sharp increase in ACC levels between predawn and midday was observed. This increase was positively correlated to the intensity of the incident solar radiation. ACC levels recorded in June at midday reached 16 000 pmol g DW and in October values of 1000 pmol g−1 DW were observed. In contrast, in drought‐stressed plants predawn concentrations of ABA were up to 130‐fold those of recovered plants, and the levels of ABA scored at midday were double of those scored at predawn. In conclusion, although drought‐stressed rosemary plants showed a relatively moderate ABA accumulation (approximately 500 pmol g−1 DW#, at predawn), it seems to be an essential factor for the regulation of the plant response to stress, thereby enabling a rapid recovery after stress release, although other mechanisms can not be excluded. As drought stress did not induce ACC accumulation, it was concluded that ethylene production was not a major factor in the drought stress resistance of rosemary plants. The increased ACC and ABA concentrations at midday were correlated with day length and light intensity and not with the water status of the plant.
Cloning of nodule‐specific cDNAs ofGalega orientalis
Authors: Kaijalainen Seppo , Schroda Michael , Lindström Kristina
Published: March 2003

Differential display was applied in order to clone cDNAs expressed exclusively or predominantly in nodules, compared to uninoculated root tissue ofGalega orientalis. Forty‐five fragments were unique for nodule RNA. These fragments were reamplified and cloned. Six of them produced a nodule‐specific signal on Northern hybridization. These six fragments were sequenced. Five of the sequenced fragments showed homology to nodulin‐gene sequences in databases, among themVicia fabamRNA for protein showing partial homology withMedicago sativanodulin‐25 (Nms25),Pisum sativumPsN466,V. fabaCCP2 and CCP4,P. sativumENOD3,andMaackia amurensisENOD2. The remaining sequence had no significant homology with sequences in the databanks. Full‐size cDNA for the homologue toV. fabamRNA for the protein showing partial homology withM. sativanodulin‐25 (Nms25) andP. sativumPsN466 were cloned and sequenced.
Sucrose uptake, invertase localization and gene expression in developing fruit of Lycopersicon esculentum and the sucrose‐accumulating Lycopersicon hirsutum
Authors: Miron Dafna , Petreikov Marina , Carmi Nir , Shen Shmuel , Levin Ilan , Granot David , Zamski Eliezer , Schaffer Arthur A.
Published: March 2003

By using immunolocalization and differential extraction methods we show that only apoplastic invertase, but not vacuolar invertase, was present in the mature, sucrose‐accumulating L. hirsutum pericarp. In contrast, in the hexose‐accumulating L. esculentum fruit, both the apoplastic and vacuolar invertase activities and protein content increase in the mature fruit. Quantitative expression studies of the soluble invertase gene (TIV1) and the apoplastic invertase genes (LINs) showed that only TIV1 gene expression could account for the species and developmental differences of both soluble and insoluble enzyme activity of the pericarp. The expression of the LIN genes encoding for apoplastic tomato invertases was unrelated to the differences in bound enzyme activity and could not account for the rise in bound invertase activity in the mature L. esculentum fruit. Evidence is presented that the bound invertase activity of tomato fruit is also the TIV1 gene product. The presence of apoplastic invertase in the mature sucrose‐accumulating L. hirsutum fruit suggests a hydrolysis‐resynthesis mechanism of sucrose uptake. In order to test this hypothesis, we studied short‐ and long‐term uptakes of asymmetrically labelled 3H‐fructosyl‐sucrose accompanied by compartmental analysis of the sugars in attached whole fruits of L. hirsutum and L. esculentum. The results indicate that hydrolysis‐resynthesis is slow in the sucrose‐accumulating fruit but is not an integral part of an uptake and compartmentation mechanism.
Characterization of S‐adenosylmethionine synthetase genes and its expression is associated with ethylene synthesis in mustard (Brassica juncea)
Authors: Lim Chin‐Chin , Liu Jian‐Zhong , Pua Eng‐Chong
Published: March 2003

S‐Adenosylmethionine synthetase (SAMS, EC 2.5.1.6) catalyses the conversion of methionine to S‐adenosylmethionine, which is a precursor of ethylene biosynthesis. To investigate whether regulation of ethylene synthesis is associated with transcript accumulation of SAMS, we report the isolation and characterization of one mustard genomic clone (MSAMS2) and two cDNAs (MSAMS3, and MSAMS4) that are highly homologous to plant SAMS. While both MSAMS2 and MSAMS3 encoded a single polypeptide of 393 amino acid residues, MSAMS4 encoded a protein of 390 residues. Accumulation of SAMS transcripts varied with mustard organs, in which transcripts were found to accumulate predominantly in root, flower bud, seedpod and leaf of the flowering plant but were less abundant in stem, petiole and leaf of the vegetative plant. SAMS transcripts could be upregulated in a gene‐specific manner in response to exogenous applications of 1‐aminocyclopropane‐1‐carboxylate, 2‐chloroethylphosphonic acid, AgNO3, polyamines (putrescine, spermidine and spermine) and NaCl. Most treatments were stimulatory to MSAMS2 and MSAMS3 transcript accumulation but salt had no effect on MSAMS2 expression. With respect to MSAMS4, the expression was generally low in control leaves and was not affected by most treatments, but exogenous applications of putrescine and spermidine upregulated transcript accumulation. The level of ethylene produced in leaves was also increased significantly in response to various stimuli, but exogenous polyamines were inhibitory to ethylene production after 12 h of incubation. These results indicate that ethylene biosynthesis in mustard is regulated, at least in part, by SAMS at the transcript level in a gene‐specific manner.
Cloning of a pine germin‐like protein (GLP) gene promoter and analysis of its activity in transgenic tobacco Bright Yellow 2 cells
Authors: Mathieu Mélanie , Neutelings Godfrey , Hawkins Simon , Grenier Emmanuel , David Hélène
Published: March 2003

Germins and germin‐like proteins (GLPs) constitute a large and highly diverse family of ubiquitous plant cell wall proteins. These proteins seem to be involved in many developmental stages and stress‐related processes, but their exact participation in these processes generally remains obscure. In Pinus caribaea Morelet, the PcGER1 gene is expressed uniquely in embryo tissues, and encodes a GLP ionically bound to the walls of pine embryo cells maintained in 2,4‐D‐containing medium. We have cloned a genomic fragment including the 1520 bp 5′‐upstream promoter region of PcGER1. This sequence contains, in its 1200 bp distal part, several cis elements (e.g. SEF4, 60 kDa protein, ABA RE and Dof recognition sites) present in genes responding to hormones and/or expressed in embryo or seed tissues, or during germination. The PcGER1 promoter sequence was cloned upstream of the GUS (β‐glucuronidase) reporter gene and transferred to tobacco Bright Yellow 2 (BY‐2) cells via Agrobacterium tumefaciens‐mediated transformation. Promoter activity and growth performances of transgenic asynchronous cell suspensions were analysed in the presence or absence of 2,4‐D and/or BA. Optimal growth, maximum cell‐wall yield and PcGER1 promoter activity were observed in the presence of 2,4‐D and BA at day 4, the end of the exponential growth phase where 70–75% cells have a 2C DNA content. Analysis of promoter activity during the cell cycle in an aphidicoline‐synchronized culture suggested that the expression is maximum in G1 cells. We also showed that under optimal growth conditions, 5′ promoter deletions decreased the activity of the reporter gene. We discuss the function of this gene with regards to cell growth.

Accession number: The PcGER1 promoter sequence was submitted to the genbank database under the accession number AY077704.
Effect of phosphorus deficiency on aluminium‐induced citrate exudation in soybean (Glycine max)
Authors: Nian Hai , Ahn Sung Ju , Yang Zhen Ming , Matsumoto Hideaki
Published: March 2003

Aluminium (Al) toxicity or phosphorus (P) deficiency can induce exudation of organic acids from the roots of some plants, which is believed to be a tolerance mechanism against Al toxicity or P deficiency. In the present study, the effect of P deficiency on Al‐induced citrate exudation was investigated in three soybean varieties differing in low‐P tolerance. P starvation alone failed to induce secretion of organic acids from all three soybean varieties. However, P deficiency altered Al‐induced citrate exudation over time, showing a complex interaction. Short × term P starvation (4 days) produced up to 50% increase in Al‐induced citrate secretion, while longer‐term (10 days) starvation reduced Al‐induced citrate secretion to trace amounts. However, after a further 1 day in complete nutrient solution for recovery, Al‐induced citrate exudation from the recovered roots was approximately 6 times higher than that from the continuously P‐starved plants, but still approximately 3.6 times lower than that from the P‐sufficient control. With increasing P or Al supply, Al‐induced citrate exudation increased, while Al accumulation in soybean roots decreased in parallel with the decrease of P supply. The photosynthetic rate, stomatal conductance and transpiration were decreased by P deficiency, whereas the intracellular CO2 concentration was increased. These findings indicate that P nutrition has a significant effect on Al‐induced citrate exudation and Al accumulation in soybean root apices.
Cytomegalovirus infection and cardiac allograft vasculopathy
Authors: Koskinen P.K. , Kallio E.A. , Tikkanen J.M. , Sihvola R.K. , Häyry P.J. , Lemström K.B.
Published: March 2003

There is a wealth of clinical and experimental evidence indicating the interaction of cytomegalovirus (CMV) infection and rejection in cardiac and other solid organ allografts. A plausible explanation for this association comes from data showing that therapy with biologicals, sepsis, and rejection, all lead to the release of TNF‐α which, upon binding to its receptor, activates NF‐kB. TNF‐α is also able to stimulate the activity of the CMV‐IE enhancer/promoter region. CMV infection of several cell lines leads to NF‐kB activation. NF‐kB binding sites are present in regulatory regions of various cellular and viral genes, including the IE enhancer region of CMV. In a reciprocal situation, CMV infection, most likely via γ‐interferon, leads to upregulation of MHC antigens in the transplant and, thereby, to increased transplant immunogenicity. Thus, a vicious circle is induced. We have investigated in detail the pathobiology of CMV and allograft vasculopathy (chronic rejection) in experimental animals, using aortic and cardiac allografts as well as a trachea model. The results may be summarized as follows: Infection of the recipient with rat CMV results in an early inflammatory response in the aortic and cardiac allograft vascular adventitia and intima (endothelialitis) and in the airway wall of tracheal allografts. This early inflammatory response leads to enhanced intimal thickness in aortic and cardiac allografts and enhanced luminal occlusion of tracheal allografts. Timewise, this coincides with early activation of intragraft inflammatory leukocytes and increased mRNA of various growth factors and cytokines. When the recipients receive gancyclovir, the enhanced intimal response in aortic and cardiac allografts and luminal occlusion in tracheal allografts is entirely abolished. Gancyclovir treatment dramatically reduces the inflammatory response in the allograft, and thereby growth factor synthesis in response to injury. However, gancyclovir does not prevent the expression of IE antigen of CMV, suggested to inactivate tumor suppressor protein p53 predisposing smooth muscle cells to increased growth. Taken together, the effect of CMV infection on cardiac allograft dysfunction is bidirectional and biphasic. The bidirectional nature emerges from the observations that acute CMV infection may accelerate acute rejection, and, on the other hand, acute alloimmune response‐associated cytokine response may activate latent CMV infection. The biphasic effect of CMV on allograft dysfunction refers to its early and late detrimental effects, i.e. during the time of acute and chronic rejection. These two effects of CMV on allograft dysfunction emphasize the need for precise diagnosis of CMV infection in transplant recipients and pre‐emptive or prophylactic anti‐viral therapy. The benefits of this strategy may not be evident during the early post‐transplant period, but 5–10 years after transplantation they manifest as better graft survival
Note.
Emerging fungal pathogens: evolving challenges to immunocompromised patients for the twenty‐first century
Authors: Walsh T.J. , Groll A.H.
Published: March 2003

Opportunistic fungi have emerged during the past decade as important causes of morbidity and mortality in immunocompromised patients. Candida species constitute the third to fourth most common causes of nosocomial blood stream infections, and Aspergillus species have emerged as the most common infectious cause of pneumonic mortality in bone marrow/stem cell transplant recipients. Among HIV‐infected patients, meningoencephalitis due to Cryptococcus neoformans ranks among the most common AIDS‐defining infections. Hyaline septated filamentous fungi, such as Fusarium species, Acremonium species, Paecilomyces species, and Trichoderma species, are increasingly reported as causing invasive mycoses refractory to conventional therapy. Dematiaceous septated filamentous fungi, such as Pseudallescheria boydii, Bipolaris species, and Cladophialophora bantiana cause pneumonia, sinusitis, and CNS infection unresponsive to current therapy. An increasing number of different members of the class of Zygomycetes are reported as causing lethal infections, despite aggressive medical and surgical interventions. Yet the treatment for zygomycosis has not changed in approximately 40 years. The prevalence of the endemic mycoses, such as those due to Penicillium marneffei, Coccidioides immitis, and Histoplasma capsulatum, has been reported to expand rapidly in response to environmental exposures and increased numbers of vulnerable hosts in endemic regions of the world. Dermatophytoses are occurring with increasing prevalence and morbidity in elderly and immunocompromised patients. As we enter the next millennium, we may anticipate that emergent fungal infections will continue to develop in the settings of permissive environmental conditions, selective antifungal pressure, and an expanding population of immunocompromised hosts. Note
Investigation and control of aspergillosis and other filamentous fungal infections in solid organ transplant recipients
Authors: Patterson J.E. , Peters J. , Calhoon J.H. , Levine S. , Anzueto A. , Al‐Abdely H. , Sanchez R. , Patterson T.F. , Rech M. , Jorgensen J.H. , Rinaldi M.G. , Sako E. , Johnson S. , Speeg V. , Halff G.A. , Trinkle J.K.
Published: March 2003

Filamentous fungal infections are associated with high morbidity and mortality in solid organ transplant patients, and prevention is warranted whenever possible. An increase in invasive aspergillosis was detected among solid organ transplant recipients in our institution during 1991–92. Rates of Aspergillus infection (18.2%) and infection or colonization (42%) were particularly high among lung transplant recipients. Epidemiologic investigation revealed cases to be both nosocomial and community‐acquired, and preventative efforts were directed at both sources. Environmental controls were implemented in the hospital, and itraconazole prophylaxis was given in the early period after lung transplantation. The rate of Aspergillus infection in solid organ transplant recipients decreased from 9.4% to 1.5%, and mortality associated with this disease decreased from 8.2% to 1.8%. The rate of Aspergillus infection or colonization among lung transplant recipients decreased from 42% to 22.5%; nosocomial Aspergillus infection decreased from 9% to 3.2%. Cases of aspergillosis in lung transplant recipients were more likely to be early infections in the pre‐intervention period. Early mortality in lung transplant recipients decreased from 15% to 3.2%. Two cases of dematiaceous fungal infection were detected, and no further cases occurred after environmental controls. The use of environmental measures that resulted in a decrease in airborne fungal spores, as well as antifungal prophylaxis, was associated with a decrease in aspergillosis and associated mortality in these patients. Ongoing surveillance and continuing intervention is needed for prevention of infection in high‐risk solid organ transplant patients.
Cytomegalovirus drug resistance and clinical implications
Authors: Chou S.W.
Published: March 2003

Antiviral agents are commonly used for cytomegalovirus (CMV) prophylaxis or therapy after solid organ transplantation. Until recently, the detection of drug‐resistant CMV in this setting was rare, but ganciclovir resistance has now been reported to occur in 5–10% of high‐risk patient subsets, such as those undergoing primary CMV infection. Persistent viral shedding or progressive CMV disease after several weeks of antiviral therapy may indicate a problem with drug resistance, though laboratory testing is required to confirm this. Rapid genotypic assays for specific mutations in the viral UL97 phosphotransferase or UL54 DNA polymerase genes can be used to detect resistance and predict cross‐resistance to other drugs. The emergence of drug resistance may be reduced by optimization of host immunity, use of potent antiviral drug regimens, and adherence to dosing regimens that adequately suppress viral replication.
Multicenter US study of hospital resource utilization associated with cytomegalovirus‐related readmission of renal and heart transplant patients
Authors: Henderson R. , Carlin D. , Kohlhase K. , Leader S.
Published: March 2003

Incidence of cytomegalovirus (CMV)‐related rehospitalization and associated resource use were captured by the Transplant Infection Cost Analysis (TICA) program, which examined patient records and hospital billing data in multiple solid organ transplant centers in the US. The experiences of two adult heart and three adult renal transplant centers were each pooled for analysis. Financial data were standardized to 1998 US dollars using the Medical Care component of the US Consumer Price Index. CMV‐related readmissions among renal transplant patients averaged 10.5 days (range 1–56) with average charges of $22,598. Heart transplant patients readmitted for CMV incurred an average charge of $42,111 and average hospital stay of 10.9 days (range 2–95). CMV‐related hospital resource use represented a significant portion of the average cost of the original transplant and associated length of stay.