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Tomato Plants (tomato + plant)
Kinds of Tomato Plants Selected AbstractsSlCCD7 controls strigolactone biosynthesis, shoot branching and mycorrhiza-induced apocarotenoid formation in tomatoTHE PLANT JOURNAL, Issue 2 2010Jonathan T. Vogel Summary The regulation of shoot branching is an essential determinant of plant architecture, integrating multiple external and internal signals. One of the signaling pathways regulating branching involves the MAX (more axillary branches) genes. Two of the genes within this pathway, MAX3/CCD7 and MAX4/CCD8, encode carotenoid cleavage enzymes involved in generating a branch-inhibiting hormone, recently identified as strigolactone. Here, we report the cloning of SlCCD7 from tomato. As in other species, SlCCD7 encodes an enzyme capable of cleaving cyclic and acyclic carotenoids. However, the SlCCD7 protein has 30 additional amino acids of unknown function at its C terminus. Tomato plants expressing a SlCCD7 antisense construct display greatly increased branching. To reveal the underlying changes of this strong physiological phenotype, a metabolomic screen was conducted. With the exception of a reduction of stem amino acid content in the transgenic lines, no major changes were observed. In contrast, targeted analysis of the same plants revealed significantly decreased levels of strigolactone. There were no significant changes in root carotenoids, indicating that relatively little substrate is required to produce the bioactive strigolactones. The germination rate of Orobanche ramosa seeds was reduced by up to 90% on application of extract from the SlCCD7 antisense lines, compared with the wild type. Additionally, upon mycorrhizal colonization, C13 cyclohexenone and C14 mycorradicin apocarotenoid levels were greatly reduced in the roots of the antisense lines, implicating SlCCD7 in their biosynthesis. This work demonstrates the diverse roles of MAX3/CCD7 in strigolactone production, shoot branching, source,sink interactions and production of arbuscular mycorrhiza-induced apocarotenoids. [source] Tomato yellow leaf curl virus, the intracellular dynamics of a plant DNA virusMOLECULAR PLANT PATHOLOGY, Issue 1 2003Yedidya Gafni SUMMARY Tomato yellow leaf curl virus is a geminivirus, transmitted by whitefly ( Bemisia tabaci ) and causing the most destructive disease of tomato throughout the Mediterranean region, the Middle East and the tropical regions of Africa and Central America. Affected plants produce either no fruits or a few small fruits. Since it is an ssDNA virus which replicates in the host cell nucleus, the molecular mechanisms involved in the viral nuclear import have been the focus of our studies in recent years and results as well as prospects will be discussed. Taxonomy:Tomato yellow leaf curl virus (TYLCV) is a ssDNA plant virus, a member of the family Geminiviridae , of the genus Begomovirus. Physical properties: ,TYLCV, like all members of Geminiviridae, has geminate (twinned) particles, 18,20 nm in diameter, 30 nm long, apparently consisting of two incomplete T = 1 icosahedra joined together in a structure with 22 pentameric capsomers and 110 identical protein subunits (Fig. 1). Figure 1. Particles of TYLCV. Electron micrograph of purified, negatively stained TYLCV particles. Bar = 100 nm. Disease symptoms: ,Symptoms become visible in tomato in approximately 2,3 weeks after infection (Fig. 2). Leaf symptoms include chlorotic margins, small leaves that are cupped, thick and rubbery. The majority (up to 90%) of flowers abscise after infection, and therefore few fruits are produced. In Israel and elsewhere, weeds bridge the gap as potential perennial host and source of the virus between tomato growing seasons. Figure 2. Tomato yellow leaf curl symptoms on tomato plant. Leaves show yellowing on the edges accompanied by upward curling. Disease control: ,Control of TYLCV is currently based on insecticide treatments and/or physical barriers against the insect vector (Bemisia tabaci), and on tomato breeding programs based on introgression of resistance or tolerance from wild species to cultivated tomato. Useful website: , Impact of chemical elicitor applications on greenhouse tomato plants and population growth of the green peach aphid, Myzus persicaeENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006Anthony J. Boughton Abstract Recent advances in the understanding of plant signaling pathways have opened the way for using elicitor-induced plant resistance as a tactic for protecting plants against arthropod pests. Four common elicitors of induced responses in tomato, Lycopersicon esculentum Mill. (Solanaceae), were evaluated with regard to phytotoxicity, induction of plant defensive proteins, and effects on population growth and fecundity of a common pest, the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae). Ethephon and methyl jasmonate (MJ) treatments caused varying degrees of phytotoxicity. Ethephon caused pronounced changes in plant growth form and severe, dose-dependent negative impacts on plant growth and flowering. Effects with MJ were milder, but still caused temporary inhibition of development, leading to smaller plants and delayed flowering. The commercial elicitors benzothiadiazole (BTH) and harpin did not cause detectable phytotoxicity. The highest doses of ethephon and MJ significantly increased leaf peroxidase (POD) levels but only MJ treatments significantly increased polyphenol oxidase (PPO) levels. BTH and harpin had no detectable effects on POD and PPO. Populations of green peach aphids grew significantly more slowly on plants treated with BTH or MJ than on control plants or plants treated with harpin or ethephon. Slowed aphid population growth on BTH-treated plants was due to significant reductions in aphid fecundity, although this was independent of changes in time to onset of reproduction or time to death. Aphid fecundity was also reduced on MJ-treated plants relative to controls, but this difference was not statistically significant, suggesting that other mechanisms are involved in slowing aphid population growth on MJ-treated plants. Growth of aphid populations on plants treated with a MJ,BTH mixture was reduced almost as much as with treatments of MJ alone, suggesting that antagonism between JA-dependant and SA-dependent plant signaling pathways is only mild with regard to induced defenses against aphids. [source] The structure of a local population of phytopathogenic Pseudomonas brassicacearum from agricultural soil indicates development under purifying selection pressureENVIRONMENTAL MICROBIOLOGY, Issue 3 2001Johannes Sikorski Among the isolates of a bacterial community from a soil sample taken from an agricultural plot in northern Germany, a population consisting of 119 strains was obtained that was identified by 16S rDNA sequencing and genomic fingerprinting as belonging to the recently described species Pseudomonas brassicacearum. Analysis of the population structure by allozyme electrophoresis (11 loci) and random amplified polymorphic DNA,polymerase chain reaction (RAPD,PCR; four primers) showed higher resolution with the latter method. Both methods indicated the presence of three lineages, one of which dominated strongly. Stochastic tests derived from the neutral theory of evolution (including Slatkin's exact test, Watterson's homozygosity test and the Tajima test) indicated that the population had developed under strong purifying selection pressure. The presence of strains clearly divergent from the majority of the population can be explained by in situ evolution or by influx of strains as a result of migration or both. Phytopathogenicity of a P. brassicacearum strain determined with tomato plants reached the level obtained with the type strain of the known pathogen Pseudomonas corrugata. The results show that a selective sweep was identified in a local population. Previously, a local selective sweep had not been seen in several populations of different bacterial species from a variety of environmental habitats. [source] Metabolism of fluoranthene in different plant cell cultures and intact plantsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2000Marit Kolb Abstract The metabolism of fluoranthene was investigated in 11 cell cultures of different plant species using a [14C]-labeled standard. Most species metabolized less than 5% of fluoranthene to soluble metabolites and formed less than 5% nonextractable residues during the standardized 48-h test procedure. Higher metabolic rates were observed in lettuce (Lactuca sativa, 6%), wheat (Tricitum aestivum, 9%), and tomato (Lycopersicon esculentum, 15%). A special high metabolic rate of nearly 50% was determined for the rose species Paul's Scarlet. Chromatographic analysis of metabolites extracted from aseptically grown tomato plants proved that the metabolites detected in the cell cultures were also formed in the intact plants. Metabolites produced in tomato and rose cells from [14C]-fluoranthene were conjugated with glucose, glucuronic acid, and other cell components. After acid hydrolyses, the main metabolite of both species was 1-hydroxyfluoranthene as identified by gas chromatography,mass spectrometry and high-performance liquid chromatography with diode array detection. The second metabolite formed by both species was 8-hydroxy-fluoranthene. A third metabolite in tomatoes was 3-hydroxyfluoranthene. [source] Epidemiology of tomato yellow leaf curl begomovirus in the Fayium area, EgyptEPPO BULLETIN, Issue 2 2000A. E. Aboul-Ata Tomato yellow leaf curl begomovirus (TYLCV) severely invaded tomato plantations in Egypt (Lower and Middle Egypt) in 1989. This study aimed to discover the relationship between TYLCV and other epidemic-associated factors in the Fayium area. The rate of TYLCV infection was inspected visually for three successive years (1994/1996) in the Fayium area. During the same period, whiteflies were collected for virus detection using bait-plant and DNA hybridization techniques. DAS-ELISA was used to detect mixed virus infections in tomato plants. TYLCV infection was prevalent (60,68%) and severe (2.1,3.0) in the Fayium fields. Cucumber mosaic cucumovirus (CMV) was found in some fields (5,28%) with moderate severity (1.0,20). Potato Y potyvirus (PVY) and potato leaf roll polerovirus (PLRV) were found in few fields (5,19% and 5% respectively) at very low severity. There was a negative correlation between TYLCV occurrence and distance from the source of infection, and a positive correlation (98%) between TYLCV intensity and percentage of viruliferous whiteflies in 1994 and 1995. There was no positive correlation between TYLCV and the total population of whiteflies caught during the same period. Five percent of viruliferous whiteflies, as proved by cDNA hybridization, led to 46% TYLCV infection. The same percentage of whiteflies, as shown by bioassay, led to 68% TYLCV infection. Monitoring of viruliferous whiteflies could be used for early prediction of TYLCV infection. [source] Chemotactic response of plant-growth-promoting bacteria towards roots of vesicular-arbuscular mycorrhizal tomato plantsFEMS MICROBIOLOGY ECOLOGY, Issue 3 2003Sushma Gupta Sood Abstract The chemotactic responses of the plant-growth-promoting rhizobacteria Azotobacter chroococcum and Pseudomonas fluorescens to roots of vesicular-arbuscular mycorrhizal (Glomus fasciculatum) tomato plants were determined. A significantly (P=0.05) greater number of bacterial cells of wild strains were attracted towards vesicular-arbuscular mycorrhizal tomato roots compared to non-vesicular-arbuscular mycorrhizal tomato roots. Substances exuded by roots served as chemoattractants for these bacteria. P. fluorescens was strongly attracted towards citric and malic acids, which were predominant constituents in root exudates of tomato plants. A. chroococcum showed a stronger response towards sugars than amino acids, but the response was weakest towards organic acids. The effects of temperature, pH, and soil water matric potential on bacterial chemotaxis towards roots were also investigated. In general, significantly (P=0.05) greater chemotactic responses of bacteria were observed at higher water matric potentials (0, ,1, and ,5 kPa), slightly acidic to neutral pH (6, 6.5 and 7), and at 20,30°C (depending on the bacterium) than in other environmental conditions. It is suggested that chemotaxis of P. fluorescens and A. chroococcum towards roots and their exudates is one of the several steps in the interaction process between bacteria and vesicular-arbuscular mycorrhizal roots. [source] Interactions between engineered tomato plants expressing antifungal enzymes and nontarget fungi in the rhizosphere and phyllosphereFEMS MICROBIOLOGY LETTERS, Issue 1 2008Mariangela Girlanda Abstract The introduction of genetically modified (GM) plants in agroecosystems raises concern about possible effects on nontarget species. The impact of a tomato line transformed for constitutive expression of tobacco ,-1,3-glucanase and chitinase on indigenous nonpathogenic fungi was investigated. In greenhouse experiments, no significant differences were found in the colonization by arbuscular mycorrhizal fungi. Diversity indices computed from over 20 500 colonies of culturable rhizosphere and phyllosphere saprotrophic microfungi, assigned to 165 species (plus>80 sterile morphotypes), showed no significant differences between GM and wild-type plants. Differences were found by discriminant analysis in both the rhizosphere and the phyllosphere, but such effects were minor compared with those linked to different plant growth stages. [source] Effect of vegetation management on autumn dispersal of Tetranychus urticae (Acari: Tetranychidae) from tomatoJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2009E. D. Meck Abstract Autumn dispersal of twospotted spider mite (Tetranychus urticae Koch) from tomato to overwintering host plants was studied in field experiments during 2004,2006. Three vegetation management strategies (herbicide, cultivation and no vegetation control) were established around mite-infested, senescing tomato plants. Tetranychus urticae dispersal was monitored using trap plants of common chickweed (Stellaria media) at 2, 6 and 12 m from the tomatoes within each vegetation management plot. Chickweed plants were sampled in the autumn and spring from 2004 to 2006. Sticky traps were placed next to trap plants in the autumn of 2005 to monitor aerial dispersal of mites. Mite populations infesting chickweed were low, and autumn dispersal of mites from tomatoes to the chickweed plots was considered to be short range. The vegetation management strategies had no effect on mite densities found in the chickweed, but the capture of mites on sticky traps indicated that aerial dispersal was also a means of dispersal to overwintering hosts. [source] Microbial population profiles of the microflora associated with pre- and postharvest tomatoes contaminated with Salmonella typhimurium or Salmonella montevideoJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2009X Shi Abstract Aims:, To determine the microflora profiles of pre- and postharvest tomatoes contaminated with Salmonella montevideo or S. typhimurium DT104. Methods and Results:,Salmonella montevideo or S. typhimurium was inoculated onto the flowers of tomato plants with the microflora of the subsequent fruit examined using a combination of Source Carbon Utilization and 16S rDNA-PCR profiling. From 16S rDNA profiles it was evident that tomatoes derived from Salmonella inoculated plants harboured a different microbial population compared to nontreated controls. The same result was observed for tomatoes inoculated at postharvest and subsequently stored for 14 days at 15°C. From sequencing analysis it was found that tomatoes derived from Salmonella inoculated plants but testing negative for the enteric pathogen, frequently harboured Enterobacter and Bacillus spp. In contrast, both bacterial types were not found associated with tomatoes testing positive for Salmonella. Conclusions:,Salmonella introduced onto tomatoes at pre- or postharvest alters the composition of the microbial community. The presence of Enterobacter and Bacillus spp negatively affects the persistence of Salmonella on preharvest tomatoes. Significance and Impact of the Study:,Salmonella appears to modify rather than become integrated into the microbial communities associated with tomatoes. Yet, the presence of antagonistic bacteria appears to reduce the persistence of the enteric pathogen. [source] Antisense-Mediated Depletion of Tomato Chloroplast Omega-3 Fatty Acid Desaturase Enhances Thermal ToleranceJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 9 2006Xun-Yan Liu Abstract A chloroplast-localized tomato (Lycopersicon esculentum Mill.) ,-3 fatty acid desaturase gene (LeFAD7) was isolated and characterized with regard to its sequence, response to various temperatures, and function in antisense transgenic tomato plants. The deduced amino acid sequence had four histidine-rich regions, of which three regions were highly conserved throughout the whole ,-3 fatty acid desaturase gene family. Southern blotting analysis showed that LeFAD7 was encoded by a single copy gene and had two homologous genes in the tomato genome. Northern blot showed that LeFAD7 was expressed in all organs and was especially abundant in leaf tissue. Meanwhile, expression of LeFAD7 was induced by chilling stress (4 °C), but was inhibited by high temperature (45 °C), in leaves. Transgenic tomato plants were produced by integration of the antisense LeFAD7 DNA under the control of a CaMV35S promoter into the genome. Antisense transgenic plants with lower 18:3 content could maintain a higher maximal photochemical efficiency (Fv/Fm) and O2 evolution rate than wild-type plants. These results suggested that silence of the LeFAD7 gene alleviated high-temperature stress. There was also a correlation between the low content of 18:3 resulting from silence of the LeFAD7 gene and tolerance to high-temperature stress. (Managing editor: Li-Hui Zhao) [source] Biological Control of Fusarium oxysporum f.sp. lycopersici on Tomato by Brevibacillus brevisJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2010Sunita Chandel Abstract The ability of Brevibacillus brevis to influence development of disease on tomato caused by Fusarium oxysporum f.sp. lycopersici was investigated using plants raised in Petri dish microcosms and in pots in the glasshouse. Development of symptoms on both microcosm- and glasshouse-raised tomato plants was markedly reduced in co-inoculations of F. oxysporum f.sp. lycopersici with B. brevis, compared with inoculations with the pathogen alone. Moreover, co-inoculations resulted in significant growth boosting effects on the plants, with increases in plant height in microcosms and in total root lengths in glasshouse-raised plants. In microcosm-raised plants, the carrier used to inoculate seed with B. brevis, either carboxymethyl cellulose (CMC) or vermiculite, had no effect on the persistence of the biological control agent on roots in the absence of inoculation with the pathogen. By contrast, numbers of B. brevis recovered from the rhizosphere and rhizoplane of inoculated plants in microcosms were four orders of magnitude lower than in plants treated with B. brevis alone. Moreover, higher numbers of B. brevis CFU were re-isolated from the rhizosphere of plants arising from CMC-coated seed, than vermiculite-coated seed. The carrier had no effect on disease control. Inhibition of conidial germination and germ-tube extension of F. oxysporum f.sp. lycopersici by cell-free filtrates of B. brevis cultures varied significantly depending on the culture medium used for suspension. These results indicate that B. brevis is a potential biological control agent for reducing the impact of F. oxysporum f.sp. lycopersici on tomato. [source] Transmission of Pepino mosaic virus by the Fungal Vector Olpidium virulentusJOURNAL OF PHYTOPATHOLOGY, Issue 4 2010Ana Alfaro-Fernández Abstract Transmission of Pepino mosaic virus (PepMV) by the fungal vector Olpidium virulentus was studied in two experiments. Two characterized cultures of the fungus were used as stock cultures for the assay: culture A was from lettuce roots collected in Castellón (Spain), and culture B was from tomato roots collected in Murcia (Spain). These fungal cultures were maintained in their original host and irrigated with sterile water. The drainage water collected from irrigating these stock cultures was used for watering PepMV-infected and non-infected tomato plants to constitute the acquisition,source plants of the assay, which were divided into six different plots: plants containing fungal culture A (non-infected and PepMV-infected); plants containing fungal culture B (non-infected and PepMV-infected); PepMV-infected plants without the fungus; and plants non-infected either with PepMV and the fungus. Thirty-six healthy plants grouped into six plots, which constituted the virus acquisition,transmission plants of the assay, were irrigated with different drainage waters obtained by watering the different plots of the acquisition,source plants. PepMV was only transmitted to plants irrigated with the drainage water collected from PepMV-infected plants whose roots contained the fungal culture B from tomato with a transmission rate of 8%. No infection was detected in plants irrigated with the drainage water collected from plots with only a fungus or virus infection. Both the virus and fungus were detected in water samples collected from the drainage water of the acquisition,source plants of the assay. These transmission assays demonstrated the possibility of PepMV transmission by O. virulentus collected from tomato crops. [source] Association of Pepino mosaic virus with Tomato CollapseJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2005S. Soler-Aleixandre Abstract Since 1998 collapse of tomato plants has been producing significant losses in protected tomato crops along the Spanish Mediterranean coast. Affected plants show sudden and progressive wilt followed by total collapse and death. Analysis of the distribution and accumulation of Pepino mosaic virus (PepMV) in collapsed and non-collapsed plants and the presence of the virus in all analysed collapsed plants suggests a relationship of this Potexvirus with tomato collapse. The fact that collapse does not occur on PepMV-free farms reinforces this hypothesis. PepMV-infected plants showed a necrotic area in the vascular system, mainly in the basal area of the stem. This necrosis was more pronounced in collapsed plants and in the areas with higher viral concentration. Our hypothesis is that tomato collapse would be associated with necrosis of the vascular system caused by PepMV accumulation. [source] Localized and Systemic Increase of Phenols in Tomato Roots Induced by Glomus versiforme Inhibits Ralstonia solanacearumJOURNAL OF PHYTOPATHOLOGY, Issue 10 2004H. H. Zhu Abstract Ralstonia solanacearum is an important plant pathogen in tropical and subtropical countries. Here, we describe the inhibition of R. solanacearum as a result of increased phenols induced locally or systemically by an arbuscular mycorrhizal (AM) fungus. In pot cultures, R. solanacearum populations in the rhizosphere, on root surfaces and in the xylem were decreased by 26.7, 79.3 and 81.7%, respectively, following inoculation of tomato plants (Lycopersicon esculentum Mill.) with Glomus versiforme Berch. Colonization of the plants by both R. solanacearum and G. versiforme increased the contents of soluble phenols and cell-wall bound phenols in root tissue, but with different patterns. Whereas R. solanacearum preferably promoted the cell-wall bound phenol content, G. versiforme preferably enhanced the soluble phenol content. Split root experiments revealed that R. Solanacearum was inhibited by G. versiforme, and that G. versiforme also increased the phenol content systemically, but to a lesser extent than locally. [source] Genome Organization of an Infectious Clone of Tomato Leaf Curl Virus (Philippines), a New Monopartite Begomovirus*JOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2002Tatsuya Kon Abstract Complete nucleotide sequence of infectious cloned DNA of Tomato leaf curl virus from Philippines (ToLCV-Ph) was determined. The single circular DNA molecule comprises 2755 nucleotides. ToLCV-Ph DNA contains six open reading frames (ORFs) each capable of encoding proteins with a molecular weight greater than 10 kDa. A partial dimeric ToLCV-Ph DNA clone was constructed in a binary vector and used to agroinoculate tomato plants (Lycopersicon esculentum Mill. cv. Zuikou 102). Typical leaf curl symptoms were observed, showing that the single DNA component is sufficient for infectivity. In total nucleotide sequence comparisons with other geminiviruses, ToLCV-Ph was most closely related to Ageratum yellow vein virus (AYVV) (79% identity), ToLCV-Laos (78%), Soyabean crinkle leaf virus -Thailand (78%) and ToLCV-Taiwan (77%). The significant but relatively low sequence identity in the genomic DNA between ToLCV-Ph and other geminiviruses suggests that it is a distinct geminivirus in the genus Begomovirus. [source] Dual Role for Ethylene in Susceptibility of Tomato to Verticillium WiltJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2001M. M. Robison Abstract Ethylene has been observed to both inhibit and promote the symptoms of Verticillium wilt (caused by Verticillium dahliae) in tomato. To test the hypothesis that ethylene has different effects at different stages in the infection process, ethylene levels were manipulated in V. dahliae -infected tomato plants by the application of an ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG) and/or ethylene's biosynthetic precursor 1-aminocyclopropane-1-carboxylate (ACC) and the effects on disease severity were examined. Statistically significant reductions in disease severity were consistently obtained for AVG-treated plants that had ACC added at the time of inoculation. A model is therefore proposed in which post-infection ethylene enhances Verticillium wilt development in tomato whereas its presence at the time of infection inhibits disease development. [source] Impact of organic and inorganic fertilizers on yield, taste, and nutritional quality of tomatoesJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2006Anuschka Heeb Abstract In a greenhouse experiment, tomato plants were grown in sand culture to test whether different fertilization regimes (mineral or organic fertilizers) at low (500 mg N plant,1 week,1) and high (750 mg N plant,1 week,1) nitrogen levels affected yield, nutritional quality, and taste of the fruits. In the mineral-fertilizer treatments, nitrate- or ammonium-dominated nutrient solutions were used. Organic fertilizer was supplied as fresh cut grass-clover mulch (a total of 2.4,kg and 3.6,kg were given per plant at low and high N level, respectively) without (orgN) and with additional sulfur fertilization (orgN+S). Yields of red tomatoes from the organically fertilized plants were significantly lower (1.3,1.8,kg plant,1) than yields from plants that received mineral fertilizer (2.2,2.8,kg plant,1). At the final harvest, yields of green tomatoes in the organic treatment with extra sulfur were similar (1.1,1.2,kg plant,1) to the NO -dominated treatments at both nutrient levels and the NH -dominated treatment at high nutrient level. Organic fertilizers released nutrients more slowly than mineral fertilizers, resulting in decreased S and P concentrations in the leaves, which limited growth and yield in the orgN treatments. Analysis of tomato fruits and plants as well as taste-test results gave no conclusive answer on the relationship between sugar or acid contents in the fruits, macronutrient content of plant leaves and fruits, and perceived taste. Sugar contents were higher in the fruits given mineral fertilizer, whereas acid contents were higher in the fruits given organic fertilizer. Preference in taste was given to the tomatoes from plants fertilized with the nitrate-dominated nutrient solution and to those given organic fertilizer with extra sulfur. Thus, a reduction in growth, which was expected to lead to a higher concentration of compounds like sugars and acids, did not result in better taste. Overall, it can be concluded that an appropriate nutrient supply is crucial to reach high yields and good taste. [source] Effects of nitrate-, ammonium-, and organic-nitrogen-based fertilizers on growth and yield of tomatoesJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2005Anuschka Heeb Abstract Mineral and organic fertilizers contain different forms and amounts of nitrogen (N), which can affect yield and product quality. The aim of this study was to determine appropriate amounts of N applied as nitrate (NO), ammonium (NH), and organic N (a mixture based on chicken manure) for optimal growth and quality of tomatoes. A pot experiment with sand as substrate was established in a greenhouse with six-week-old tomato plants (Lycopersicon esculentum Mill. cv. "Armada"). Nitrogen was applied in nutrient solutions at different NO : NH ratios combined with different chloride levels (NO -dominated, NO = NH at low Cl,, NO = NH at high Cl,, and NH -dominated, respectively) or as organic N at four N-application rates (250, 500, 750, 1000 mg N plant,1 week,1). No significant differences in shoot biomass and yields of red tomatoes were observed between NO - or NH -fed plants. Nitrogen rates above 750 mg N plant,1 week,1 did not significantly increase marketable fruit yield, but enhanced shoot-biomass production. The NH -N-dominated treatments (which also had high Cl, concentrations) showed increasing incidence of blossom-end-rot (BER)-infected fruits. In the organic-N treatments, shoot-biomass production and yields were lower than in the inorganic-N treatments, but fruit quality was good with few BER-infected fruits. The results show that with a total N supply below 750 mg N plant,1 week,1, NH can be used as equivalent N source to NO, resulting in equivalent yields of marketable fruit under the conditions in this experiment. Einfluss von Nitrat, Ammonium und organischem Stickstoff auf Wachstum und Ertrag von Tomaten Mineralische und organische Dünger enthalten verschiedene Formen von und Mengen an Stickstoff (N), welche den Ernteertrag und die Produktqualität beeinflussen können. Das Ziel dieser Arbeit war es, geeignete N-Mengen , appliziert als Nitrat, Ammonium oder organischer Stickstoff , für optimales Wachstum und Qualität von Tomaten zu bestimmen. Dazu wurde mit sechs Wochen alten Tomatenpflanzen (Lycopersicon esculentum Mill. cv. "Armada") unter Gewächshausbedingungen mit Sand als Substrat ein Gefäßversuch angelegt. Die Applikation von N erfolgte in Form von Nährlösungen mit verschiedenen NO:NH -Verhältnissen, kombiniert mit unterschiedlichen Chlorid (Cl)-Konzentrationen (NO -dominiert, NO = NH bei niedrigem Cl,, NO = NH bei hohem Cl, und NH -dominiert) bzw. als organischer N. Jede dieser Behandlungen wurde mit vier verschiedenen N-Mengen angelegt (250, 500, 750, 1000 mg N Pflanze,1 Woche,1). Zwischen den mit Nitrat und Ammonium gedüngten Pflanzen konnte kein signifikanter Unterschied in Sprosswachstum und Ertrag an erntereifen Tomaten festgestellt werden. Stickstoffmengen über 750 mg N Pflanze,1 Woche,1 steigerten den Ertrag verkaufsfähiger Tomaten nicht signifikant, obwohl die Produktion an Sprossbiomasse noch anstieg. In den NH -dominiert gedüngten Gefäßen mit gleichzeitig hohen Cl-Konzentrationen in den Nährlösungen wurden häufiger Tomaten mit Blütenendfäule beobachtet. In den Behandlungen mit organischem Stickstoff waren die Sprossbiomasseproduktion und der Ertrag geringer als in den mineralisch gedüngten Behandlungen, aber die Qualität der Früchte war gut, mit nur wenigen durch Blütenendfäule geschädigten Tomaten. Die Ergebnisse zeigen, dass bei einer Stickstoffversorgung unter 750 mg N Pflanze,1 Woche,1 Ammonium anstelle von Nitrat verwendet werden kann. Im vorliegenden Versuch wurden unter diesen Bedingungen vergleichbare Erträge verkaufsfähiger Früchte erzielt. [source] Ralstonia solanacearum requires type 4 pili to adhere to multiple surfaces and for natural transformation and virulenceMOLECULAR MICROBIOLOGY, Issue 2 2002Yaowei Kang Summary As reported previously for Ralstonia solanacearum strain GMI1000, wild-type strains AW1 and K60 were shown to produce Hrp pili. AW1 and K60 mutants lacking Hrp pili still exhibited twitching motility, which requires type 4 pili (Tfp), and electron microscopy revealed that they still made flexuous polar pili. Twitching-positive cells had an extracellular 17 kDa protein that was associated with piliation, and an internal 43-amino-acid sequence of this protein was typical of type 4 pilins. This amino acid sequence is encoded by an open reading frame, designated pilA, in the genomic sequence of GMI1000. PilA is 46% identical to a Pseudomonas aeruginosa type 4 pilin over its entire length and has all the conserved residues and motifs characteristic of type 4 group A pilins. pilA mutants did not make the 17 kDa PilA protein and did not exhibit twitching motility. When compared with its parent, an AW1 pilA mutant was reduced in virulence on tomato plants and in autoaggregation and biofilm formation in broth culture. Unlike AW1, a pilA mutant did not exhibit polar attachment to tobacco suspension culture cells or to tomato roots; it was also not naturally competent for transformation. We reported previously that twitching motility ceases in maturing AW1 colonies and that inactivation of PhcA, a global transcriptional regulator, results in colonies that continue to exhibit twitching motility. Similarly, in broth culture, expression of a pilA::lacZ fusion in AW1 decreased 10-fold at high cell density, but expression remained high in a phcA mutant. In addition, pilA::lacZ expression was positively regulated 10-fold by PehR, a response regulator that is known to be repressed by PhcA. This signal cascade is sufficient to explain why pilA expression, and thus twitching motility, decreases at high cell densities. [source] RNAi-mediated resistance to Potato spindle tuber viroid in transgenic tomato expressing a viroid hairpin RNA constructMOLECULAR PLANT PATHOLOGY, Issue 4 2009NORA SCHWIND SUMMARY Because of their highly ordered structure, mature viroid RNA molecules are assumed to be resistant to degradation by RNA interference (RNAi). In this article, we report that transgenic tomato plants expressing a hairpin RNA (hpRNA) construct derived from Potato spindle tuber viroid (PSTVd) sequences exhibit resistance to PSTVd infection. Resistance seems to be correlated with high-level accumulation of hpRNA-derived short interfering RNAs (siRNAs) in the plant. Thus, although small RNAs produced by infecting viroids [small RNAs of PSTVd (srPSTVds)] do not silence viroid RNAs efficiently to prevent their replication, hpRNA-derived siRNAs (hp-siRNAs) appear to effectively target the mature viroid RNA. Genomic mapping of the hp-siRNAs revealed an unequal distribution of 21- and 24-nucleotide siRNAs of both (+)- and (,)-strand polarities along the PSTVd genome. These data suggest that RNAi can be employed to engineer plants for viroid resistance, as has been well established for viruses. [source] Response of superoxide dismutase isoenzymes in tomato plants (Lycopersicon esculentum) during thermo-acclimation of the photosynthetic apparatusPHYSIOLOGIA PLANTARUM, Issue 3 2007Daymi Camejo Seedlings of Lycopersicon esculentum Mill. var. Amalia were grown in a growth chamber under a photoperiod of 16 h light at 25°C and 8 h dark at 20°C. Five different treatments were applied to 30-day-old plants: Control treatment (plants maintained in the normal growth conditions throughout the experimental time), heat acclimation (plants exposed to 35°C for 4 h in dark for 3 days), dark treatment (plants exposed to 25°C for 4 h in dark for 3 days), heat acclimation plus heat shock (plants that previously received the heat acclimation treatment were exposed to 45°C air temperature for 3 h in the light) and dark treatment plus heat shock (plants that previously received the dark treatment were exposed to 45°C air temperature for 3 h in the light). Only the heat acclimation treatment increased the thermotolerance of the photosynthesis apparatus when the heat shock (45°C) was imposed. In these plants, the CO2 assimilation rate was not affected by heat shock and there was a slight and non-significant reduction in maximum carboxylation velocity of Rubisco (Vcmax) and maximum electron transport rate contributing to Rubisco regeneration (Jmax). However, the plants exposed to dark treatment plus heat shock showed a significant reduction in the CO2 assimilation rate and also in the values of Vcmax and Jmax. Chlorophyll fluorescence measurements showed increased thermotolerance in heat-acclimated plants. The values of maximum chlorophyll fluorescence (Fm) were not modified by heat shock in these plants, while in the dark-treated plants that received the heat shock, the Fm values were reduced, which provoked a significant reduction in the efficiency of photosystem II. A slight rise in the total superoxide dismutase (SOD) activity was found in the plants that had been subjected to both heat acclimation and heat shock, and this SOD activity was significantly higher than that found in the plants subjected to dark treatment plus heat shock. The activity of Fe-SOD isoenzymes was most enhanced in heat-acclimated plants but was unaltered in the plants that received the dark treatment. Total CuZn-SOD activity was reduced in all treatments. Darkness had an inhibitory effect on the Mn-SOD isoenzyme activity, which was compensated by the effect of a rise in air temperature to 35°C. These results show that the heat tolerance of tomatoplants may be increased by the previous imposition of a moderately high temperature and could be related with the thermal stability in the photochemical reactions and a readjustment of Vcmax and Jmax. Some isoenzymes, such as the Fe-SODs, may also play a role in the development of heat-shock tolerance through heat acclimation. In fact, the pattern found for these isoenzymes in heat-acclimated Amalia plants was similar to that previously described in other heat-tolerant tomato genotypes. [source] Electromagnetic fields (900 MHz) evoke consistent molecular responses in tomato plantsPHYSIOLOGIA PLANTARUM, Issue 2 2006David Roux First page of article [source] Aphid parasitoids detect that an alien plant was present nearby during their developmentPHYSIOLOGICAL ENTOMOLOGY, Issue 3 2002H. F. Van Emden Abstract Glasshouse and laboratory experiments were conducted with Aphidius rhopalosiphi parasitizing Metopolophium dirhodum to test whether the presence in the same environment of another plant species (tomato or marigold) induced aerial allelopathy in wheat plants. Emerging parasitoids were offered the choice of two odours of wheat plants in an olfactometer , wheat grown alone and wheat grown in the presence of the second plant species. Female parasitoids responded more strongly than males, but both sexes preferred the odour of wheat grown in the environment in which they had developed (i.e. with or without the second plant species present). Moving the tomato plants from the cages where they had been placed with wheat to the cages that had previously had wheat alone just before the aphid mummy formed showed that the odour environment the emerging parasitoid responded to was that of the mummy rather than that of the developing parasitoid larva. From this it was concluded that the parasitoids in the olfactometer were responding not only to wheat volatiles, but also to tomato volatiles absorbed on the surface of the mummy and encountered by the emerging adult parasitoid. By excising the parasitoid pupa from the mummy formed on one wheat cultivar, and offering the emerging parasitoids the surface of aphid mummies formed on a different cultivar, it was confirmed that olfactometer responses represented a learning of the chemistry of the surface of the mummy encountered at or after emergence. [source] (GATA)4 DNA fingerprinting identifies morphologically characterized ,San Marzano' tomato plantsPLANT BREEDING, Issue 2 2006R. Rao Abstract Currently, registration, protection and breeding of the ,San Marzano' tomato cultivar rely on a number of morphological descriptors. Its correct identification is essential in order to preserve this variety, which is highly valued and known worldwide, from an increasing number of similar cultivars with inferior organoleptic features. However, the identification of this cultivar on the exclusive basis of morpho-agronomic traits has some intrinsic limits and therefore, molecular signatures are required to efficiently discriminate plants and their fruits, and to characterize and make profitable use of the traditional accessions. The phenotype and genotype of 25 ,San Marzano' tomato accessions cultivated in the traditional area are characterized, along with the most popular peeling tomato cultivars, using a combination of DNA molecular analysis and morphological descriptors. (GATA)4 DNA fingerprinting proved to be a powerful tool for the analysis of the ,San Marzano' cultivar and in the description of the genetic inconsistencies present in the locally cultivated traditional ,San Marzano' collections. [source] Parasitism by Cuscuta pentagona sequentially induces JA and SA defence pathways in tomatoPLANT CELL & ENVIRONMENT, Issue 2 2010JUSTIN B. RUNYON ABSTRACT While plant responses to herbivores and pathogens are well characterized, responses to attack by other plants remain largely unexplored. We measured phytohormones and C18 fatty acids in tomato attacked by the parasitic plant Cuscuta pentagona, and used transgenic and mutant plants to explore the roles of the defence-related phytohormones salicylic acid (SA) and jasmonic acid (JA). Parasite attachment to 10-day-old tomato plants elicited few biochemical changes, but a second attachment 10 d later elicited a 60-fold increase in JA, a 30-fold increase in SA and a hypersensitive-like response (HLR). Host age also influenced the response: neither Cuscuta seedlings nor established vines elicited a HLR in 10-day-old hosts, but both did in 20-day-old hosts. Parasites grew larger on hosts deficient in SA (NahG) or insensitive to JA [jasmonic acid-insensitive1 (jai1) ], suggesting that both phytohormones mediate effective defences. Moreover, amounts of JA peaked 12 h before SA, indicating that defences may be coordinated via sequential induction of these hormones. Parasitism also induced increases in free linolenic and linoleic acids and abscisic acid. These findings provide the first documentation of plant hormonal signalling induced by a parasitic plant and show that tomato responses to C. pentagona display characteristics similar to both herbivore- and pathogen-induced responses. [source] The plasma membrane Na+/H+ antiporter SOS1 is essential for salt tolerance in tomato and affects the partitioning of Na+ between plant organsPLANT CELL & ENVIRONMENT, Issue 7 2009RAQUEL OLÍAS ABSTRACT We have identified a plasma membrane Na+/H+ antiporter gene from tomato (Solanum lycopersicum), SlSOS1, and used heterologous expression in yeast to confirm that SlSOS1 was the functional homolog of AtSOS1. Using post-transcriptional gene silencing, we evaluated the role played by SlSOS1 in long-distance Na+ transport and salt tolerance of tomato. Tomato was used because of its anatomical structure, more complex than that of Arabidopsis, and its agricultural significance. Transgenic tomato plants with reduced expression of SlSOS1 exhibited reduced growth rate compared to wild-type (WT) plants in saline conditions. This sensitivity correlated with higher accumulation of Na+ in leaves and roots, but lower contents in stems of silenced plants under salt stress. Differential distribution of Na+ and lower net Na+ flux were observed in the xylem sap in the suppressed plants. In addition, K+ concentration was lower in roots of silenced plants than in WT. Our results demonstrate that SlSOS1 antiporter is not only essential in maintaining ion homeostasis under salinity, but also critical for the partitioning of Na+ between plant organs. The ability of tomato plants to retain Na+ in the stems, thus preventing Na+ from reaching the photosynthetic tissues, is largely dependent on the function of SlSOS1. [source] Ethylene insensitivity impedes a subset of responses to phosphorus deficiency in tomato and petuniaPLANT CELL & ENVIRONMENT, Issue 12 2008HYE-JI KIM ABSTRACT The role of ethylene in growth and developmental responses to low phosphorus stress was evaluated using ethylene-insensitive ,Never-ripe' (Nr) tomato and etr1 petunia plants. Low phosphorus increased adventitious root formation in ,Pearson' (wild-type) tomato plants, but not in Nr, supporting a role for ethylene in adventitious root development and showing that ethylene is important for this aspect of phosphorus response. Low phosphorus reduced ethylene production by adventitious roots of both genotypes, suggesting that ethylene perception , not production , regulates carbon allocation to adventitious roots at the expense of other roots under low phosphorus stress. With the exception of its effect on adventitious rooting, Nr had positive effects on growth and biomass accumulation in tomato whereas etr1 tended to have negative effects on petunia. This was particularly evident during the recovery from transplanting, when the effective quantum yield of photosystem II of etr1 petunia grown with low phosphorus was significantly lower than ,Mitchell Diploid', suggesting that etr1 petunia plants may undergo more severe post-transplant stress at low phosphorus availability. Our results demonstrate that ethylene mediates adventitious root formation in response to phosphorus stress and plays an important role for quick recovery of plants exposed to multiple environmental stresses, i.e. transplanting and low phosphorus. [source] Glycinebetaine accumulation is more effective in chloroplasts than in the cytosol for protecting transgenic tomato plants against abiotic stressPLANT CELL & ENVIRONMENT, Issue 8 2007EUNG-JUN PARK ABSTRACT Tomato (Lycopersicon esculentum Mill. cv. Moneymaker) plants were transformed with a gene for choline oxidase (codA) from Arthrobacter globiformis. The gene product (CODA) was targeted to the chloroplasts (Chl,codA), cytosol (Cyt,codA) or both compartments simultaneously (ChlCyt,codA). These three transgenic plant types accumulated different amounts and proportions of glycinebetaine (GB) in their chloroplasts and cytosol. Targeting CODA to either the cytosol or both compartments simultaneously increased total GB content by five- to sixfold over that measured from the chloroplast targeted lines. Accumulation of GB in codA transgenic plants was tissue dependent, with the highest levels being recorded in reproductive organs. Despite accumulating, the lowest amounts of GB, Chl,codA plants exhibited equal or higher degrees of enhanced tolerance to various abiotic stresses. This suggests that chloroplastic GB is more effective than cytosolic GB in protecting plant cells against chilling, high salt and oxidative stresses. Chloroplastic GB levels were positively correlated with the degree of oxidative stress tolerance conferred, whereas cytosolic GB showed no such a correlation. Thus, an increase in total GB content does not necessarily lead to enhanced stress tolerance, but additional accumulation of chloroplastic GB is likely to further raise the level of stress tolerance beyond what we have observed. [source] An engineered sorbitol cycle alters sugar composition, not growth, in transformed tobaccoPLANT CELL & ENVIRONMENT, Issue 10 2006MICHIHITO DEGUCHI ABSTRACT Many efforts have been made to engineer stress tolerance by accumulating polyols. Transformants that accumulate polyols often show growth inhibition, because polyols are synthesized as a dead-end product in plants that do not naturally accumulate polyols. Here, we show a novel strategy in which a sorbitol cycle was engineered by introducing apple cDNA encoding NAD-dependent sorbitol dehydrogenase (SDH) in addition to sorbitol-6-phosphate dehydrogenase (S6PDH). Tobacco plants transformed only with S6PDH showed growth inhibition, and very few transformants were obtained. In contrast, many transgenic plants with both S6PDH and SDH were easily obtained, and their growth was normal despite their accumulation of sorbitol. Interestingly, the engineered sorbitol cycle enhanced the accumulation of sucrose instead of fructose that was expected to be increased. Sucrose, rather than fructose, was also increased in the immature fruit of tomato plants transformed with an antisense fructokinase gene in which the phosphorylation of fructose was inhibited. A common phenomenon was observed in the metabolic engineering of two different pathways, showing the presence of homeostatic regulation of fructose levels. [source] | ||||||||||||||||||||||||||||