Suramin inhibits initiation of defense signaling by systemin, chitosan, and a β-glucan elicitor in suspension-cultured Lycopersicon peruvianum cells

Systemin-mediated defense signaling in tomato (Lycopersicon esculentum) plants is analogous to the cytokine-mediated inflammatory response in animals. Herein, we report that the initiation of defense signaling in suspension-cultured cells of Lycopersicon peruvianum by the peptide systemin, as well as by chitosan and β-glucan elicitor from Phytophtora megasperma, is inhibited by the polysulfonated naphtylurea compound suramin, a known inhibitor of cytokine and growth factor receptor interactions in animal cells. Using a radioreceptor assay, we show that suramin interfered with the binding of the systemin analog 125I-Tyr-2,Ala-15-systemin to the systemin receptor with an IC50 of 160 μM. Additionally, labeling of the systemin receptor with a photoaffinity analog of systemin was inhibited in the presence of suramin. Receptor-mediated tyrosine phosphorylation of a 48-kDa mitogen-activated protein kinase and alkalinization of the medium of suspension-cultured cells in response to systemin and carbohydrate elicitors were also inhibited by suramin. The inhibition of medium alkalinization by suramin was reversible in the presence of high concentrations of systemin and carbohydrate elicitors. Calyculin A and erythrosin B, intracellular inhibitors of phosphatases and plasma membrane proton ATPases, respectively, both induce medium alkalinization, but neither response was inhibited by suramin. The polysulfonated compound heparin did not inhibit systemin-induced medium alkalinization. NF 007, a suramin derivative, induced medium alkalinization, indicating that neither NF 007 nor heparin interact with elicitor receptors like suramin. The data indicate that cell-surface receptors in plants show some common structural features with animal cytokine and growth factor receptors that can interact with suramin to interfere with ligand binding.

Método de obtenção de híbridos interespecíficos entre Lycopersicon esculentum e L. peruvianum

A transferência de genes da espécie silvestre Lycopersicon peruvianum para a espécie L. esculentum por processo convencional de hibridação é limitada por incompatibilidade. O objetivo deste trabalho foi desenvolver um método de obtenção de híbridos entre essas duas espécies, mediante a técnica de cultura de óvulos, tendo em vista o interesse em transferir genes presentes em acessos de L. peruvianum que conferem resistência a Septoria lycopersici. Foram utilizados os acessos CNPH 946, CNPH 947 e CNPH 948 de L. peruvianum e as cultivares Floradade e Ipa-5 de L. esculentum. Sementes híbridas de frutos com 25-68 dias após a polinização foram colocadas para germinar inicialmente em meio de cultura Murashige & Skoog (MS), e posteriormente em meio HLH. As sementes foram incubadas no escuro a 25°C. Só foram regenerados os híbridos provenientes das sementes colocadas para germinar em meio HLH. Dezesseis híbridos foram obtidos de 1.573 óvulos, sendo de 1% a taxa de regeneração de plantas híbridas. As características morfológicas dos híbridos F1 quando comparadas com os dois genitores indicaram que as plantas eram realmente resultado da hibridação entre L. esculentum e L. peruvianum.

Structural analysis and molecular model of a self-incompatibility RNase from wild tomato

Self-incompatibility RNases (S-RNases) are an allelic series of style glycoproteins associated with rejection of self-pollen in solanaceous plants. The nucleotide sequences of S-RNase alleles from several genera have been determined, but the structure of the gene products has only been described for those from Nicotiana alata. We report on the N-glycan structures and the disulfide bonding of the S-3-RNase from wild tomato (Lycopersicon peruvianum) and use this and other information to construct a model of this molecule. The S-3-RNase has a single N-glycosylation site (Asn-28) to which one of three N-glycans is attached. S-3-RNase has seven Cys residues; six are involved in disulfide linkages (Cys-16-Cys-21, Cys-46-Cys-91, and Cys-166-Cys-177), and one has a free thiol group (Cys-150). The disulfide-bonding pattern is consistent with that observed in RNase Rh, a related RNase for which radiographic-crystallographic information is available. A molecular model of the S-3-RNase shows that four of the most variable regions of the S-RNases are clustered on one surface of the molecule. This is discussed in the context of recent experiments that set out to determine the regions of the S-RNase important for recognition during the self-incompatibility response.

Structural Analysis and Molecular Model of a Self-Incompatibility RNase from Wild Tomato1

Self-incompatibility RNases (S-RNases) are an allelic series of style glycoproteins associated with rejection of self-pollen in solanaceous plants. The nucleotide sequences of S-RNase alleles from several genera have been determined, but the structure of the gene products has only been described for those from Nicotiana alata. We report on the N-glycan structures and the disulfide bonding of the S3-RNase from wild tomato (Lycopersicon peruvianum) and use this and other information to construct a model of this molecule. The S3-RNase has a single N-glycosylation site (Asn-28) to which one of three N-glycans is attached. S3-RNase has seven Cys residues; six are involved in disulfide linkages (Cys-16-Cys-21, Cys-46-Cys-91, and Cys-166-Cys-177), and one has a free thiol group (Cys-150). The disulfide-bonding pattern is consistent with that observed in RNase Rh, a related RNase for which radiographic-crystallographic information is available. A molecular model of the S3-RNase shows that four of the most variable regions of the S-RNases are clustered on one surface of the molecule. This is discussed in the context of recent experiments that set out to determine the regions of the S-RNase important for recognition during the self-incompatibility response.

Intra and interspecific variability of in vitro culture response in Lycopersicon (tomatoes)

Intra and interspecific variability was measured in the genus Lycopersicon for the traits: productivity rate (PR, total number of regenerated shoots/total number of cultures), regeneration percentage (%R, number of cultures regenerating shoots or primordia/total number of cultures) and callus percentage (%C, number of cultures only producing callus/total number of cultures). Leaf explants from various genotypes of L. esculentum, L. esculentum var. cerasiforme, L. pimpinellifolium and L. peruvianum were placed on Murashige and Skoog (Physiol. Plant. 15: 473-493, 1962) medium + 0.175 mg/l IAA + 2.25 mg/l BA. Significant differences among species and among genotypes within the same species were found, while genotypes from different species showed similar responses.

Acquired tolerance of tomato (Lycopersicon esculentum cv. Micro-Tom) plants to cadmium-induced stress

The effects of varying concentrations of cadmium (Cd) on the development of Lycopersicon esculentum cv. Micro-Tom (MT) plants were investigated after 40 days (vegetative growth) and 95 days (fruit production), corresponding to 20 days and 75 days of exposure to CdCl(2), respectively. Inhibition of growth was clearly observed in the leaves after 20 days and was greater after 75 days of growth in 1 mM CdCl(2), whereas the fruits exhibited reduced growth following the exposure to a concentration as low as 0.1 mM CdCl(2). Cd was shown to accumulate in the roots after 75 days of growth but was mainly translocated to the upper parts of the plants accumulating to high concentrations in the fruits. Lipid peroxidation was more pronounced in the roots even at 0.05 mM CdCl(2) after 75 days, whereas in leaves, there was a major increase after 20 days of exposure to 1 mM CdCl(2), but the fruit only exhibited a slight significant increase in lipid peroxidation in plants subjected to 1 mM CdCl(2) when compared with the control. Oxidative stress was also investigated by the analysis of four key antioxidant enzymes, which exhibited changes in response to the increasing concentrations of Cd tested. Catalase (EC 1.11.1.6) activity was shown to increase after 75 days of Cd treatment, but the major increases were observed at 0.1 and 0.2 mM CdCl(2), whereas guaiacol peroxidase (EC 1.11.1.7) did not vary significantly from the control in leaves and roots apart from specific changes at 0.5 and 1 mM CdCl(2). The other two enzymes tested, glutathione reductase (EC 1.6.4.2) and superoxide dismutase (SOD, EC 1.15.1.1), did not exhibit any significant changes in activity, apart from a slight decrease in SOD activity at concentrations above 0.2 mM CdCl(2). However, the most striking results were obtained when an extra treatment was used in which a set of plants was subjected to a stepwise increase in CdCl(2) from 0.05 to 1 mM, leading to tolerance of the Cd applied even at the final highest concentration of 1 mM. This apparent adaptation to the toxic effect of Cd was confirmed by biomass values being similar to the control, indicating a tolerance to Cd acquired by the MT plants.

Effect of peel and seed removal on the nutritional value and antioxidant activity of tomato (Lycopersicon esculentum L.) fruits

The effect of peel and seed removal, two commonly practiced procedures either at home or by the processing industry, on the physicochemical properties, bioactive compounds contents and antioxidant capacity of tomato fruits of four typical Portuguese cultivars (cereja, chucha, rama and redondo) were appraised. Both procedures caused significant nutritional and antioxidant activity losses in fruits of every cultivar. In general, peeling was more detrimental, since it caused a higher decrease in lycopene, bcarotene, ascorbic acid and phenolics contents (averages of 71%, 50%, 14%, and 32%, respectively) and significantly lowered the antioxidant capacity of the fruits (8% and 10%, using DPPH. and b-carotene linoleate model assays, correspondingly). Although seeds removal favored the increase of both color and sweetness, some bioactive compounds (11% of carotenoids and 24% of phenolics) as well as antioxidant capacity (5%) were loss. The studied cultivars were differently influenced by these procedures. The fruits most affected by peeling were those from redondo cultivar (-66% lycopene, -44% b-carotene, -26% ascorbic acid and -38% phenolics). Seeds removal, in turn, was more injurious for cereja tomatoes (-10% lycopene, -38% b-carotene, -25% ascorbic acid and -63% phenolics). Comparatively with the remaining ones, the rama fruits were less affected by the trimming procedures.

Pre-meal tomato (Lycopersicon esculentum) intake can have anti-obesity effects in young women?

The effect of pre-meal tomato intake in the anthropometric indices and blood levels of triglycerides, cholesterol, glucose, and uric acid of a young women population (n=35, 19.6 ± 1.3 years) was evaluated. During 4 weeks, daily, participants ingested a raw ripe tomato (~90 g) before lunch. Their anthropometric and biochemical parameters were measured repeatedly during the follow-up time. At the end of the 4 weeks, significant reductions were observed on body weight (-1.09 ± 0.12 kg on average), % fat (-1.54 ± 0.52%), fasting blood glucose (-5.29 ± 0.80 mg/dl), triglycerides (-8.31 ± 1.34 mg/dl), cholesterol (-10.17 ± 1.21 mg/ dl), and uric acid (-0.16 ± 0.04 mg/dl) of the participants. The tomato pre-meal ingestion seemed to interfere positively in body weight, fat percentage, and blood levels of glucose, triglycerides, cholesterol, and uric acid of the young adult women that participated in this study.

Exposure of Lycopersicon Esculentum to Microcystin-LR: Effects in the Leaf Proteome and Toxin Translocation from Water to Leaves and Fruits

Natural toxins such as those produced by freshwater cyanobacteria have been regarded as an emergent environmental threat. However, the impact of these water contaminants in agriculture is not yet fully understood. The aim of this work was to investigate microcystin-LR (MC-LR) toxicity in Lycopersicon esculentum and the toxin accumulation in this horticultural crop. Adult plants (2 month-old) grown in a greenhouse environment were exposed for 2 weeks to either pure MC-LR (100 μg/L) or Microcystis aeruginosa crude extracts containing 100 μg/L MC-LR. Chlorophyll fluorescence was measured, leaf proteome investigated with two-dimensional gel electrophoresis and Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF)/TOF, and toxin bioaccumulation assessed by liquid chromatography-mass spectrometry (LC-MS)/MS. Variations in several protein markers (ATP synthase subunits, Cytochrome b6-f complex iron-sulfur, oxygen-evolving enhancer proteins) highlight the decrease of the capacity of plants to synthesize ATP and to perform photosynthesis, whereas variations in other proteins (ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit and ribose-5-phosphate isomerase) suggest an increase of carbon fixation and decrease of carbohydrate metabolism reactions in plants exposed to pure MC-LR and cyanobacterial extracts, respectively. MC-LR was found in roots (1635.21 μg/kg fw), green tomatoes (5.15–5.41 μg/kg fw), mature tomatoes (10.52–10.83 μg/kg fw), and leaves (12,298.18 μg/kg fw). The results raise concerns relative to food safety and point to the necessity of monitoring the bioaccumulation of water toxins in agricultural systems affected by cyanotoxin contamination.

AVALIAÇÃO DE PROGÊNIES DE TOMATE (LYCOPERSICON ESCULENTUM) PARA CULTIVO SOB TEMPERATURAS ELEVADAS

Foram avaliadas três progênies F7 de tomate άο cruzamento HT-16, do programa de melhoramento genético do Departamento de Ciências Agronômicas do INPA, para o caráter pegamento de frutos. Os ensaios foram realizados em casa de vegetação com cobertura de plástico transparente e por um período de 37 dias, que cobriu toda a fase de florescimento e frutificação do primeiro ao oitavo racimo; tomou-se dados sobre a temperatura do ar no interior da casa de vegetação, por meio de um termohigrógrafo. A amplitude de variação da temperatura foi de 18° C (mínimo) até 43° C (máximo). Os resultados mostraram a ocorrência de variabilidade genética entre e dentro das progênies avaliadas para o caráter percentagem de pega mento de frutos, sendo possível sua exploração em processos seletivos visando obter linhagens com alta capacidade de pegamento de frutos sob condição de cultivo em temperaturas elevadas.

Efeitos do ácido 2-cloroetilfosfônico na maturação de frutos do tomateiro (Lycopersicon esculentum Mill. cv. 'São Sebastião')

Estudou-se a influência do ácido 2-cloroetilfosfônico (ethephon), aplicado em pré-maturação, na frutificação do tomateiro de crescimento indeterminado, cultivar 'São Sebastião'; em condições de casa de vegetação. Pela análise da produtividade verificou-se que o regulador de crescimento acelerou significativamente a maturação dos frutos, incrementando o peso e o número total de frutos por planta obtidos nas primeiras colheitas, sendo isto compensado por diminuições significativas em colheitas posteriores. Não observou-se porém, diferenças significativas no peso e número de frutos por planta, considerando a totalidade das colheitas, entre o controle e as plantas tratadas com 1000, 2000 e 4000 ppm de ethephon.

Nutrição mineral de hortaliças: XXVII - absorção de nutrientes pelo tomateiro (Lycopersicon esculentum, Mill.), em cultivo rasteiro

Em condições de cultura rasteira, para industrialização, foi cultivado tomateiro (Lycopersicon esculentum Mill.) processando-se amostragens periódicas, em cuja matéria seca se processaram análises químicas para macro e micronutrientes, com exceção de molibdênio. Observou-se que o desenvolvimento do tomateiro se intensifica a partir do florescimento e frutificação, que ocorre após 60 dias de idade, sendo o maior número de frutos formados entre 80 e 90 dias. Foi encontrado, no final do ciclo, uma relação estreita entre número de folhas e número de frutos, de 3 para 1. São apresentados teores dos nutrientes estudados, em vários órgãos da planta, em idades diferentes. Uma cultura (57.000 plantas/ha), extrai as seguintes quantidades: N-67 kg; P-4,76 kg; K-101 kg; Ca-24 kg; Mg-18,5 kg; S-5,3 kg; B-86 g; Cu-37 g; Fe-1353 g; Mn-393 g; Zn-119 g.

Ação de reguladores de crescimento no peso médio dos frutos de tomateiro (Lycopersicon esculentum Mill.)

Estudaram-se os efeitos da aplicação de sulfato de amônio e reguladores de crescimento no peso médio dos frutos de tomateiro (Lycopersicon esculentum Mill.) cultivares "Angela" e "Roma". Em dois ensaios efetuou-se a aplicação de (NH4)2 SO4 (2g/l solo), SADH 3000 ppm, SADH + (NH4)2 SO4, CCC 2000 ppm, CCC+ (NH4)2 SO4, GA 100 ppm, GA + (NH4)2 SO4, além do tratamento controle. Em outros dois ensaios, além do controle, realizou-se a aplicação de 1-(2,4-diclorofenoxiacetil) -3,5- dimetil pirasol 3,75, 15,00 e 7,50 ppm, e de CEPA nas concentrações de 500, 1000 e 1500 ppm. Verificou-se que o SADH promoveu redução no peso médio dos frutos dos tomateiros "Angela", em relação ao tratamento com (NH4)2 SO4. A incorporação de sulfato de amônio no solo restringiu os efeitos detrimentals da aplicação foliar de SADH. Pulverização com CCC, GA, Tomakon e CEPA não afetou o peso médio dos frutos das cultivares "Angela" e "Roma".

Ocorrência da podridão estilar em tomateiros (Lycopersicon esculentum Mill.) sob o efeito de reguladores de crescimento

Estudaram-se em condições de casa de vegetação os efeitos da aplicação de reguladores de crescimento na ocorrência da podridão estilar nos frutos de tomateiro cultivar "Miguel Pereira". Observou-se que ácido giberélico na concentração de 100 ppm promoveu alta incidência da anomalia fisiológica em plantas tratadas com altas dosagens de sulfato de amônio. Sob as mesmas condições, tomateiros pulverizados com ácido succínico -2.2-dimetilhidrazida 4.000 ppm, cloreto de (2-cloroetil) trimetilamônio 2.000 ppm e ácido - 3 - indolacético 100 ppm, apresentaram baixa incidência de podridão estilar. Efetuaram-se determinações dos teores de N, R, K, Ca e Mg nas folhas, hastes e frutos dos tomateiros normais e daqueles mostrando a anomalia fisiológica. Realizaram-se análises químicas dos substratos de plantio e foi proposto um mecanismo da incidência da podridão estilar em tomateiros.

Ação de reguladores vegetais no crescimento de tomateiro (Lycopersicon esculentum Mill. cv. «Miguel Pereira»)

Estudaram-se em condições de casa de vegetação, os efeitos da aplicação de reguladores vegetais no crescimento do tomateiro cultivar "Miguel Pereira". Além do tratamento controle, aplicou-se, 44 dias após a semeadura, cloreto de (2-cloroetil) trimetilamônio 2.000 ppm, ácido succínico -2,2-dimetilhidrazida 3.000 ppm e ácido giberélico 100 ppm. Observou-se que o GA promoveu maior crescimento, em relação ao controle. O crescimento do tomateiro mostrou-se mais reduzido nas plantas tratadas com CCC e SADH, com relação àquelas pulverizadas com GA e plantas controle.