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1.
Chemosphere ; 258: 127350, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554012

RESUMO

The adverse effects of glyphosate herbicide on plants are well recognised, however, potential hormetic effects have not been well studied. This study aimed to use tomato as a model organism to explore the potential hormetic effects of glyphosate in water (0-30 mg L-1) and in compost soil (0-30 mg kg-1). The growth-promoting effects of glyphosate at concentrations of 0.03-1 mg L-1 in water or 0.03-1 mg kg-1 in compost were demonstrated in tomato for the first time. These hormetic effects were manifest as increased hypocotyl and radicle growth of seedlings germinated on paper towel soaked in glyphosate solution and also in crops which had been sprayed with glyphosate. Increased rates of photosynthesis (up to 2-fold) were observed in 4-week old crops when seeds were sown in compost amended with glyphosate and also when leaves were sprayed with glyphosate. The examination of chloroplast morphology using transmission electron microscopy revealed that the hormetic effects were associated with elongation of chloroplasts, possibly due to lateral expansion of thylakoid grana.


Assuntos
Germinação/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Lycopersicon esculentum/fisiologia , Cloroplastos/efeitos dos fármacos , Produtos Agrícolas/efeitos dos fármacos , Glicina/toxicidade , Hormese/efeitos dos fármacos , Lycopersicon esculentum/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Plântula/efeitos dos fármacos , Sementes/efeitos dos fármacos , Solo
2.
J Plant Physiol ; 250: 153184, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32464590

RESUMO

Although it is well known that parasitic weeds such as Orobanche (broomrape) significantly reduce the yield of economically important crops, their infection-induced oxidative changes need more exploration in their host plants. Moreover, applying an eco-friendly approach to minimize the infection is not yet available. This study was conducted to understand the effect of Orobanche ramosa infection on oxidative and redox status of tomato plants and the impact of hormonal (indole acetic acid (IAA); 0.09 mM and salicylic acid (SA); 1.0 mM) seed-priming upon mitigating the infection threats. Although Orobanche invades tomato roots, its inhibitory effects on shoot biomass were also indicted. Orobanche infection usually induces oxidative damage i.e., high lipid peroxidation, lipoxygenase activity and H2O2 levels, particularly for roots. Interestingly, hormonal seed-priming significantly enhanced tomato shoots and roots growth under both healthy and infected conditions. Also, IAA and SA treatment significantly reduced Orobanche infection-induced oxidative damage. The protective effect of seed-priming was explained by increasing the antioxidant defense markers including the antioxidant metabolites (i.e., total antioxidant capacity, carotenoids, phenolics, flavonoids, ASC, GSH, tocopherols) and enzymes (CAT, POX, GPX, SOD, GR, APX, MDHAR, DHAR), particularly in infected tomato seedlings. Additionally, cluster analysis indicated the differential impact of IAA- and SA-seed-priming, whereas lower oxidative damage and higher antioxidant enzymes' activities in tomato root were particularly reported for IAA treatment. The principal component analysis (PCA) also proclaimed an organ specificity depending on their response to Orobanche infection. Collectively, here and for the first time, we shed the light on the potential of seed-priming with either IAA or SA to mitigate the adverse effect of O. ramosa stress in tomato plants, especially at oxidative stress levels.


Assuntos
Ácidos Indolacéticos/farmacologia , Lycopersicon esculentum/fisiologia , Orobanche/fisiologia , Estresse Oxidativo/fisiologia , Reguladores de Crescimento de Planta/farmacologia , Plantas Daninhas/fisiologia , Ácido Salicílico/farmacologia , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/parasitologia , Estresse Oxidativo/efeitos dos fármacos , Sementes/efeitos dos fármacos , Sementes/parasitologia , Sementes/fisiologia
3.
Chemosphere ; 256: 127042, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32450352

RESUMO

Carbon nanotube (CNT) applications are increasing in consumer products, including agriculture devices, making them an important contaminant to study in the field of plant nanotoxicology. Several studies have observed the uptake and effects of CNTs in plants. However, in other studies differing results were observed on growth and physiology depending on the plant species and type of CNT. This study focused on the effects of CNTs on plant phenotype with growth, time to flowering, fruiting time as endpoints, and physiology, through amino acid and phytohormone content, in tomato after exposure to multiple types of CNTs. Plants grown in CNT-contaminated soil exhibited a delay in early growth and flowering (especially in treatments of 1 mg/kg multi-walled nanotubes (MWNTs), 10 mg/kg MWNTs, and 1 mg/kg MWNTs-COOH). However, CNTs did not affect plant growth or height later in the life cycle. No significant differences in abscisic acid (ABA) and citrulline content were observed between the treated and control plants. However, single-walled nanotube (SWNT) exposure significantly increased salicylic acid (SA) content in tomato. These results suggest that SWNTs may elicit a stress response in tomatoes. Results from this study offer more insight into how plants respond and acclimate to CNTs. These results will lead to a better understanding of CNT impact on plant phenotype and physiology.


Assuntos
Lycopersicon esculentum/fisiologia , Nanotubos de Carbono/química , Frutas , Reguladores de Crescimento de Planta/metabolismo
4.
Artigo em Inglês | MEDLINE | ID: mdl-32333252

RESUMO

Cadmium (Cd) is probably the most damaging metal to plant species; with a long biological half-life, it can be taken up by plants, disrupting the cell homeostasis and triggering several metabolic pathways. Selenium (Se) improves plant defence systems against stressful conditions, but the biochemical antioxidant responses to Cd stress in tomato plants is poorly understood. To further address the relationship of Cd-stress responses with Se mineral uptake, Cd and Se concentration, proline content, MDA and H2O2 production, and the activity of SOD, APX, CAT and GR enzymes were analyzed in Micro-Tom (MT) plants submitted to 0.5 mM Cd. The results revealed different responses according to Se combination and Cd application. For instance, roots and leaves of MT plants treated with Se exhibited an increase in dry mass and nutritional status, exhibited lower proline content and higher APX and GR activities when compared with plants with no Se application. Plants submitted to 0.5 mM Cd, irrespective of Se exposure, exhibited lower proline, MDA and H2O2 content and higher SOD, CAT and GR activities. Selenium may improve tolerance against Cd, which allowed MT plants exhibited less oxidative damage to the cell, even under elevated Cd accumulation in their tissues. The results suggest that Se application is an efficient management technique to alleviate the deleterious effects of Cd-stress, enhancing the nutritional value and activity of ROS-scavenging enzymes in tomato plants.


Assuntos
Cádmio/toxicidade , Lycopersicon esculentum/fisiologia , Estresse Oxidativo/fisiologia , Selênio/metabolismo , Poluentes do Solo/toxicidade , Antioxidantes , Glutationa , Peróxido de Hidrogênio , Oxirredução , Folhas de Planta , Raízes de Plantas
5.
J Plant Physiol ; 249: 153163, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32330754

RESUMO

The effects of a newly discovered endophytic fungus, Talaromyces omanensis, on the drought tolerance of tomato is presented in this study. The fungus was obtained from a desert plant Rhazya stricta in Oman. Drought stress was induced by a 15% solution of Polyethylene glycol-6000 (PEG-6000). Several parameters were measured including pollen sterility, pollen tube length, growth, flowering, and yield characteristics, the biochemical analysis of the leaves and fruits, as well as other physiological and anatomical parameters. The results showed that T. omanensis provided multiple advantages to tomato grown under drought stress, including improved reproductive characteristics, chlorophyll fluorescence, and some anatomical characteristics such as increased phloem and cortex width and a reduction of pith autolysis that leads to hollow stem. In addition, T. omanensis significantly increased drought-stress related characteristics such as shoot dry weight, root length, the number of flowers, and fruit weight. A significantly higher concentration of gibberellic acid (GA3) was found in tomato plants treated by T. omanensis, which may enhance their drought tolerance. These results suggest that T. omanensis is a potential biological anti-stress stimulator for important horticultural crops such as tomatoes. This study is the first to report the beneficial effects of T. omanensis in alleviating drought stress in tomatoes.


Assuntos
Secas , Endófitos/fisiologia , Lycopersicon esculentum/microbiologia , Talaromyces/fisiologia , Dessecação , Lycopersicon esculentum/anatomia & histologia , Lycopersicon esculentum/fisiologia , Reprodução
6.
Science ; 367(6485): 1482-1485, 2020 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-32217727

RESUMO

The premature abscission of flowers and fruits limits crop yield under environmental stress. Drought-induced flower drop in tomato plants was found to be regulated by phytosulfokine (PSK), a peptide hormone previously known for its growth-promoting and immune-modulating activities. PSK formation in response to drought stress depends on phytaspase 2, a subtilisin-like protease of the phytaspase subtype that generates the peptide hormone by aspartate-specific processing of the PSK precursor in the tomato flower pedicel. The mature peptide acts in the abscission zone where it induces expression of cell wall hydrolases that execute the abscission process. Our results provide insight into the molecular control of abscission as regulated by proteolytic processing to generate a small plant peptide hormone.


Assuntos
Secas , Flores/fisiologia , Lycopersicon esculentum/fisiologia , Hormônios Peptídicos/fisiologia , Proteínas de Plantas/fisiologia , Estresse Fisiológico , Parede Celular/enzimologia , Etilenos , Frutas/fisiologia , Técnicas de Silenciamento de Genes , Hidrolases/fisiologia , Ácidos Indolacéticos , Peptídeos , Plantas Geneticamente Modificadas/fisiologia , Transdução de Sinais
7.
Artigo em Inglês | MEDLINE | ID: mdl-32179467

RESUMO

Light and temperature are two primary environmental factors for plant growth and development. The response of plants to multiple stresses of high light intensity and heat stress are complex. The priming effects of high light and heat stress on improving heat tolerance of plants need to be further illuminated. This study aimed to explain the effect of high light intensity, high temperature and their combination on tomato and clarify the response of tomato to heat stress after priming. Tomato plants were treated under control, high light, heat stress and the combination for the first-round treatments, followed by recurring heat stress as the second-round treatments. For the first-round treatments, the net photosynthetic rate (PN) of the plants at individual high light and individual high temperature on day four significantly increased and decreased, respectively, as compared with control. Combined stress caused significant reduction in Fv/Fm (maximum quantum efficiency of photosystem II) and chlorophyll content as well as increase in carotenoids and carbohydrates content. No significant difference in the PN was observed in tomato with and without priming; however, heat priming did improve the heat avoidance ability by increasing evaporation and decreasing leaf temperature. Overall, the high light affected the physiological response of tomatoes at heat stress. The tomato plants developed their defense systems including chlorophyll loss and synthesis of carotenoids to protect themselves from multiple stresses. Our work provided new insights into the understanding of plants response to high light and heat stress.


Assuntos
Resposta ao Choque Térmico , Temperatura Alta , Luz , Lycopersicon esculentum/fisiologia , Folhas de Planta/fisiologia , Clorofila , Lycopersicon esculentum/efeitos da radiação , Fotossíntese , Folhas de Planta/efeitos da radiação
8.
Artigo em Inglês | MEDLINE | ID: mdl-32193092

RESUMO

Tomato (Lycopersicon esculentum Mill [Solanum lycopersicum L.].) is an important food material and cash crop, as well as a model plant for genetic evolution and molecular biology research. However, as a cold-sensitive crop originating from the tropics, the growth and development of tomato is often affected by low temperature stress. Therefore, how processing tomatoes resist this type of stress has important theoretical and practical significance. In this study, the LeCOLD1 gene was cloned from processing tomato. Subcellular localization analysis showed that LeCOLD1 was located in the plasma membrane. Real-time quantitative PCR analysis showed that LeCOLD1 was highly expressed in roots. Drought, salt and low temperatures induced the expression of COLD1. Overexpression and RNA interference vectors of LeCOLD1 were constructed and were transformed into tomato by the Agrobacterium-mediated method, and then obtaining transgenic tomato plants. It was found that LeCOLD1 increased the height of processing tomato plants and increased the length of their roots. In addition, overexpression of LeCOLD1 significantly improved the cold resistance of the plants. Overexpressing LeCOLD1 in tomato plants reduced the damage to the cell membrane, accumulation of ROS and photoinhibition of PSII, and maintained the high activity of antioxidant enzymes and the content of osmotic regulators. Further analysis revealed that during low temperature stress, the cells maintained high levels of antioxidant enzyme activity by regulating the transcription of the genes encoding these enzymes. The results show that overexpressing LeCOLD1 in tomato increases the plants' resistance to low temperatures, and that reducing LeCOLD1 expression makes the plants more sensitive to low temperatures.


Assuntos
Resposta ao Choque Frio , Lycopersicon esculentum/fisiologia , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Raízes de Plantas/genética , Plantas Geneticamente Modificadas/fisiologia
9.
Proc Natl Acad Sci U S A ; 117(14): 8187-8195, 2020 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-32179669

RESUMO

A dramatic evolution of fruit size has accompanied the domestication and improvement of fruit-bearing crop species. In tomato (Solanum lycopersicum), naturally occurring cis-regulatory mutations in the genes of the CLAVATA-WUSCHEL signaling pathway have led to a significant increase in fruit size generating enlarged meristems that lead to flowers with extra organs and bigger fruits. In this work, by combining mapping-by-sequencing and CRISPR/Cas9 genome editing methods, we isolated EXCESSIVE NUMBER OF FLORAL ORGANS (ENO), an AP2/ERF transcription factor which regulates floral meristem activity. Thus, the ENO gene mutation gives rise to plants that yield larger multilocular fruits due to an increased size of the floral meristem. Genetic analyses indicate that eno exhibits synergistic effects with mutations at the LOCULE NUMBER (encoding SlWUS) and FASCIATED (encoding SlCLV3) loci, two central players in the evolution of fruit size in the domestication of cultivated tomatoes. Our findings reveal that an eno mutation causes a substantial expansion of SlWUS expression domains in a flower-specific manner. In vitro binding results show that ENO is able to interact with the GGC-box cis-regulatory element within the SlWUS promoter region, suggesting that ENO directly regulates SlWUS expression domains to maintain floral stem-cell homeostasis. Furthermore, the study of natural allelic variation of the ENO locus proved that a cis-regulatory mutation in the promoter of ENO had been targeted by positive selection during the domestication process, setting up the background for significant increases in fruit locule number and fruit size in modern tomatoes.


Assuntos
Frutas/genética , Proteínas de Homeodomínio/genética , Lycopersicon esculentum/fisiologia , Meristema/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Fatores de Transcrição/metabolismo , Proliferação de Células/genética , Produção Agrícola , Domesticação , Frutas/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Meristema/citologia , Mutação , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Locos de Características Quantitativas/genética , Células-Tronco/fisiologia , Fatores de Transcrição/genética
10.
J Photochem Photobiol B ; 203: 111745, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31931381

RESUMO

Light affects many aspects of cell development. Tomato seedlings growing at different light qualities (white, blue, green, red, far-red) and in the dark displayed alterations in cell wall structure and composition. A strong and negative correlation was found between cell wall thickness and hypocotyl growth. Cell walls was thicker under blue and white lights and thinner under far-red light and in the dark, while intermediate values was observed for red or green lights. Additionally, the inside layer surface of cell wall presented random deposited microfibrillae angles under far-red light and in the dark. However, longitudinal transmission electron microscopy indicates a high frequency of microfibrils close to parallels related to the elongation axis in the outer layer. This was confirmed by ultra-high resolution small angle X-ray scattering. These data suggest that cellulose microfibrils would be passively reoriented in the longitudinal direction. As the cell expands, the most recently deposited layers (inside) behave differentially oriented compared to older (outer) layers in the dark or under FR lights, agreeing with the multinet growth hypothesis. High Ca and pectin levels were found in the cell wall of seedlings growing under blue and white light, also contributing to the low extensibility of the cell wall. Low Ca and pectin contents were found in the dark and under far-red light. Auxins marginally stimulated growth in thin cell wall circumstances. Hypocotyl growth was stimulated by gibberellins under blue light.


Assuntos
Parede Celular/fisiologia , Luz , Lycopersicon esculentum/fisiologia , Antocianinas/análise , Cálcio/metabolismo , Parede Celular/química , Cromatografia Líquida de Alta Pressão , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/efeitos da radiação , Microfibrilas/química , Microscopia Eletrônica de Transmissão , Pectinas/metabolismo , Reguladores de Crescimento de Planta/análise , Reguladores de Crescimento de Planta/metabolismo , Análise de Componente Principal , Espalhamento a Baixo Ângulo , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Plântula/efeitos da radiação , Difração de Raios X
11.
Artigo em Inglês | MEDLINE | ID: mdl-31928668

RESUMO

Salinity threatens the productivity of tomato (Solanum lycopersicum L.). R2R3-type MYB transcription factors are important regulators in response to environmental stress. Here, we analyzed the function of the tomato R2R3-type MYB gene SlMYB102. A transcriptional activation assay showed that SlMYB102 had transactivation activity in yeast. Promoter analysis showed that multiple stress-related elements were found in the promoter of SlMYB102. Furthermore, SlMYB102 was induced by osmotic stress, particularly by salt stress. The overexpression of SlMYB102 in tomato affected multiple parameters under salinity stress. Under long-term salt stress, the degree of growth inhibition was significantly reduced in the two overexpression (OE) lines. In addition, the two OE lines maintained a better K+/Na+ ratio, lower reactive oxygen species (ROS) generation (O2•- production rate and H2O2 content) and lower electrolytic leakage rates than the wild type (WT). The activity of ROS scavenging enzymes including superoxide dismutase, peroxidase, catalase and ascorbate peroxidase, and the accumulation of antioxidants (ascorbic acid and glutathione) and proline was higher in the two OE lines compared with WT. The qRT-PCR analysis confirmed that the transcript abundance of many salt stress-related genes (SlSOS1, SlSOS2, SlNHX3, SlNHX4, SlHAK5, SlCPK1 and SlCPK3) was upregulated in two OE lines under salt stress. Collectively, these results suggest that SlMYB102 participates in tomato tolerance through the regulation of a series of molecular and physiological processes.


Assuntos
Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/fisiologia , Proteínas de Plantas/genética , Tolerância ao Sal/genética , Fatores de Transcrição/genética , Lycopersicon esculentum/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/fisiologia , Salinidade , Fatores de Transcrição/metabolismo , Transcrição Genética
12.
Plant Mol Biol ; 102(4-5): 537-551, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31916084

RESUMO

KEY MESSAGE: Silencing of SlCAND1 expression resulted in dwarfish, loss of apical dominance, early flowering, suppression of seed germination, and abnormal root architecture in tomato Cullin-RING E3 ligases (CRLs)-dependent ubiquitin proteasome system mediates degradation of numerous proteins that controls a wide range of developmental and physiological processes in eukaryotes. Cullin-associated Nedd8-dissociated protein 1 (CAND1) acts as an exchange factor allowing substrate recognition part exchange and plays a vital role in reactivating CRLs. The present study reports on the identification of SlCAND1, the only one CAND gene in tomato. SlCAND1 expression is ubiquitous and positively regulated by multiple plant hormones. Silencing of SlCAND1 expression using RNAi strategy resulted in a pleiotropic and gibberellin/auxin-associated phenotypes, including dwarf plant with reduced internode length, loss of apical dominance, early flowering, low seed germination percentage, delayed seed germination speed, short primary root, and increased lateral root proliferation and elongation. Moreover, application of exogenous GA3 or IAA could partly rescue some SlCAND1-silenced phenotypes, and the expression levels of gibberellin/auxin-related genes were altered in SlCAND1-RNAi lines. These facts revealed that SlCAND1 is required for gibberellin/auxin-associated regulatory network in tomato. Although SlCAND1 is crucial for multiple developmental processes during vegetative growth stage, SlCAND1-RNAi lines didn't exhibit visible effect on fruit development and ripening. Meanwhile, we discussed that multiple physiological functions of SlCAND1 in tomato are different to previous report of its ortholog in Arabidopsis. Our study adds a new perspective on the functional roles of CAND1 in plants, and strongly supports the hypothesis that CAND1 and its regulated ubiquitin proteasome system are pivotal for plant vegetative growth but possibly have different roles in diverse plant species.


Assuntos
Flores/fisiologia , Germinação , Lycopersicon esculentum/fisiologia , Proteínas de Plantas/fisiologia , Raízes de Plantas/fisiologia , Arabidopsis/genética , Proteínas Culina , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Giberelinas/metabolismo , Lycopersicon esculentum/genética , Fenótipo , Reguladores de Crescimento de Planta/fisiologia , Proteínas de Plantas/genética , Interferência de RNA , Sementes/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/fisiologia
13.
Physiol Plant ; 168(3): 694-708, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31376304

RESUMO

Carbon dioxide concentration (CO2 ) and light intensity are known to play important roles in plant growth and carbon assimilation. Nevertheless, the underlying physiological mechanisms have not yet been fully explored. Tomato seedlings (Solanum lycopersicum Mill. cv. Jingpeng No. 1) were exposed to two levels of CO2 and three levels of light intensity and the effects on growth, leaf gas exchange and water use efficiency were investigated. Elevated CO2 and increased light intensity promoted growth, dry matter accumulation and pigment concentration and together the seedling health index. Elevated CO2 had no significant effect on leaf nitrogen content but did significantly upregulate Calvin cycle enzyme activity. Increased CO2 and light intensity promoted photosynthesis, both on a leaf-area basis and on a chlorophyll basis. Increased CO2 also increased light-saturated maximum photosynthetic rate, apparent quantum efficiency and carboxylation efficiency and, together with increased light intensity, it raised photosynthetic capacity. However, increased CO2 reduced transpiration and water consumption across different levels of light intensity, thus significantly increasing both leaf-level and plant-level water use efficiency. Among the range of treatments imposed, the combination of increased CO2 (800 µmol CO2 mol-1 ) and high light intensity (400 µmol m-2 s-1 ) resulted in optimal growth and carbon assimilation. We conclude that the combination of increased CO2 and increased light intensity worked synergistically to promote growth, photosynthetic capacity and water use efficiency by upregulation of pigment concentration, Calvin cycle enzyme activity, light energy use and CO2 fixation. Increased CO2 also lowered transpiration and hence water usage.


Assuntos
Dióxido de Carbono/farmacologia , Luz , Lycopersicon esculentum/fisiologia , Fotossíntese , Clorofila/fisiologia , Lycopersicon esculentum/efeitos da radiação , Folhas de Planta/fisiologia , Transpiração Vegetal , Plântula
14.
Food Chem ; 310: 125901, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31816533

RESUMO

The mechanism of SlMYC2, involved in methyl jasmonate (MJ)-induced tomato fruit resistance to pathogens, was investigated. The data indicated that MJ treatment enhanced the accumulation of total phenolics and flavonoids, as well as individual phenolic acids and flavonoids, which might be caused by the increased phenylalanine ammonia-lyase and polyphenol oxidase activities, induced pathogenesis-related gene (PR) expression, ß-1,3-glucanase and chitinase activities, as well as α-tomatine, by inducing GLYCOALKALOID METABOLISM gene expression. These effects, induced by MJ, partly contributed to tomato fruit resistance to Botrytis cinerea. Nevertheless, the induction effects of MJ were almost counteracted by silence of SlMYC2, and the disease incidence and lesion diameter in MJ + SlMYC2-silenced fruit were higher than those in MJ-treated fruit. These observations are the first evidence that SlMYC2 plays vital roles in MJ-induced fruit resistance to Botrytis cinerea, possibly by regulating defence enzyme activities, SlPRs expression, α-tomatine, special phenolic acids and flavonoid compounds.


Assuntos
Acetatos/metabolismo , Botrytis/patogenicidade , Ciclopentanos/metabolismo , Lycopersicon esculentum/microbiologia , Oxilipinas/metabolismo , Proteínas de Plantas/genética , Acetatos/farmacologia , Ciclopentanos/farmacologia , Resistência à Doença/fisiologia , Flavonoides/metabolismo , Frutas/efeitos dos fármacos , Frutas/microbiologia , Frutas/fisiologia , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/fisiologia , Oxilipinas/farmacologia , Fenilalanina Amônia-Liase/metabolismo , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo , Tomatina/análogos & derivados , Tomatina/metabolismo
15.
Physiol Plant ; 168(1): 27-37, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30684269

RESUMO

Plant tolerance against a combination of abiotic stresses is a complex phenomenon, which involves various mechanisms. Physiological and biochemical analyses of salinity (NaCl) and nickel (Ni) tolerance in two contrasting tomato genotypes were performed in a hydroponics experiment. The tomato genotypes selected were proved to be tolerant (Naqeeb) and sensitive (Nadir) to both salinity and Ni stress in our previous experiment. The tomato genotypes were exposed to combinations of NaCl (0, 75 and 150 mM) and Ni (0, 15, and 20 mg l-1 ) for 28 days. The results revealed that the tolerant and sensitive tomato genotypes showed similar response to NaCl and Ni stress; however, the level of response was significantly different in both genotypes. The tolerant tomato genotype showed less reduction in growth than the sensitive genotype against both NaCl and Ni stress. Root and shoot ionic analysis showed a decrease in Na and increase in K concentration by increasing Ni levels in the growth medium. Moreover, accumulation of Na and Ni in tissues showed a decrease in membrane stability index and an increase in malondialdehyde contents. The activity of superoxide dismutase, catalase, peroxidase and glutathione reductase under NaCl and Ni stress was significantly higher in the tolerant compared to the sensitive genotype. Enhanced activity of many antioxidant enzymes in Naqeeb under stress conditions is among the other mechanisms that enabled the genotype to better detoxify reactive oxygen species and therefore Naqeeb tolerated the stresses better than Nadir.


Assuntos
Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/fisiologia , Níquel/farmacologia , Cloreto de Sódio/farmacologia , Estresse Fisiológico , Antioxidantes , Catalase , Clorofila , Genótipo , Glutationa Redutase , Malondialdeído , Peroxidase , Potássio/análise , Salinidade , Sódio/análise , Superóxido Dismutase
16.
Physiol Plant ; 168(2): 406-421, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31503325

RESUMO

In plants, investigation on heavy metal toxicity and its mitigation by nutrient elements have gained much attention. However, mechanism(s) associated with nutrients-mediated mitigation of metal toxicity remain elusive. In this study, we have investigated the role and interrelation of glutathione (GSH) and hydrogen sulfide (H2 S) in the regulation of hexavalent chromium [Cr(VI)] toxicity in tomato (Solanum lycopersicum), pea (Pisum sativum) and brinjal (Solanum melongena) seedlings, supplemented with additional sulfur (S). The results show that Cr(VI) significantly reduced growth, total chlorophyll and photosynthetic quantum yield of tomato, pea and brinjal seedlings which was accompanied by enhanced intracellular accumulation of Cr(VI) in roots. Moreover, Cr(VI) enhanced the generation of reactive oxygen species in the studied vegetables, while antioxidant defense system exhibited differential responses. However, additional supply of S alleviated Cr(VI) toxicity. Interestingly, addition of l-buthionine sulfoximine (BSO, a glutathione biosynthesis inhibitor) further increased Cr(VI) toxicity even in the presence of additional S but GSH addition reverses the effect of BSO. Under similar condition, endogenous H2 S, l-cysteine desulfhydrase (DES) activity and cysteine content did not significantly differ when compared to controls. Hydroxylamine (HA, an inhibitor of DES) also increased Cr(VI) toxicity even in the presence of additional S but sodium hydrosulfide (NaHS, an H2 S donor) reverses the effect of HA. Moreover, Cr(VI) toxicity amelioration by NaHS was reversed by the addition of hypotaurine (HT, an H2 S scavenger). Taken together, the results show that GSH which might be derived from supplied S is involved in the mitigation of Cr(VI) toxicity in which H2 S signaling preceded GSH biosynthesis.


Assuntos
Cromo/toxicidade , Glutationa/fisiologia , Sulfeto de Hidrogênio/metabolismo , Lycopersicon esculentum/fisiologia , Ervilhas/fisiologia , Solanum melongena/fisiologia , Lycopersicon esculentum/efeitos dos fármacos , Ervilhas/efeitos dos fármacos , Plântula/efeitos dos fármacos , Plântula/fisiologia , Solanum melongena/efeitos dos fármacos
17.
Insect Sci ; 27(1): 58-68, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29676854

RESUMO

"Candidatus Liberibacter solanacearum" (Lso) are phloem-restricted and unculturable Gram-negative bacteria. Presently five haplotypes have been identified worldwide; but only haplotypes A and B are associated with the vector Bactericera cockerelli (Sulc.) in the Americas. Previous studies showed that Lso-infection reduces B. cockerelli reproductive output and that Lso haplotype B is more pathogenic than Lso haplotype A. To understand the interaction of Lso haplotype B and B. cockerelli, the fitness of Lso-free and Lso B-infected insects, and the expression of vitellogenin (BcVg1-like), a gene involved directly in the insect reproduction were analyzed. Statistical differences in the number of eggs oviposited, and the total number of progeny nymphs and adults were found among crosses of insects with or without Lso. Significant differences in sex proportions were found between Lso B-infected and Lso-free crosses: a higher proportion of F1 adult females were obtained from Lso B-infected mothers. A significant reduction of BcVg1-like was observed in crosses performed with Lso B-infected females compared to the Lso-free insects. In female cohorts of different age, a significant reduction of BcVg1-like expression was measured in 7-d-old Lso B-infected females (virgin and mated) compared with 7-d-old Lso-free females (virgin and mated), respectively. The reduction of BcVg1-like transcript was associated with a lower number of developing oocytes observed in female's reproductive systems. Overall, this study represents the first step to understand the interaction of Lso B with B. cockerelli, highlighting the effect of Lso B infection on egg production, BcVg1-like expression, and oocyte development.


Assuntos
Aptidão Genética , Hemípteros/fisiologia , Rhizobiaceae/fisiologia , Vitelogênese , Animais , Hemípteros/genética , Hemípteros/crescimento & desenvolvimento , Hemípteros/microbiologia , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Ninfa/fisiologia , Doenças das Plantas/microbiologia
18.
Insect Sci ; 27(1): 133-142, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29740981

RESUMO

Over 50 genera of bees release pollen from flower anthers using thoracic vibrations, a phenomenon known as buzz-pollination. The efficiency of this process is directly affected by the mechanical properties of the buzzes, namely the duration, amplitude, and frequency. Nonetheless, although the effects of the former two properties are well described, the role of buzz frequency on pollen release remains unclear. Furthermore, nearly all of the existing studies describing vibrational properties of natural buzz-pollination are limited to bumblebees (Bombus) and carpenter bees (Xylocopa) constraining our current understanding of this behavior and its evolution. Therefore, we attempted to minimize this shortcoming by testing whether flower anthers exhibit optimal frequency for pollen release and whether bees tune their buzzes to match these (optimal) frequencies. If true, certain frequencies will trigger more pollen release and lighter bees will reach buzz frequencies closer to this optimum to compensate their smaller buzz amplitudes. Two strategies were used to test these hypotheses: (i) the use of (artificial) vibrational playbacks in a broad range of buzz frequencies and amplitudes to assess pollen release by tomato plants (Solanum lycopersicum L.) and (ii) the recording of natural buzzes of Neotropical bees visiting tomato plants during pollination. The playback experiment indicates that although buzz frequency does affect pollen release, no optimal frequency exists for that. In addition, the recorded results of natural buzz-pollination reveal that buzz frequencies vary with bee genera and are not correlated with body size. Therefore, neither bees nor plants are tuned to optimal pollen release frequencies. Bee frequency of buzz-pollination is a likely consequence of the insect flight machinery adapted to reach higher accelerations, while flower plant response to buzz-pollination is the likely result of its pollen granular properties.


Assuntos
Abelhas/fisiologia , Lycopersicon esculentum/fisiologia , Polinização , Animais , Brasil , Pólen , Especificidade da Espécie , Vibração
19.
Chemosphere ; 240: 124944, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726591

RESUMO

The present study explores the potential of two chromium tolerant and plant growth promoting bacterial strains, Klebsiella sp. and Enterobacter sp. in luxuriant growth of tomato plants under chromium stress conditions. For the assessment of potentiality of the two selected strains, a pot scale experiment was setup with tomato plant under different levels of chromium contamination. In pot experiment, different plant growth parameters, oxidative stress tolerance and chromium bioremediation potential were studied upon inoculation of the selected bacterial strains. The results of pot experiment showed that both the strains were effective in promotion of plant growth and enhanced the plant biomass but Enterobacter sp. was more prominent in enhancement of root length, shoot length, fresh and dry weight, and nutrient uptake in tomato plant. The enhancement of enzymes to combat oxidative stress in tomato plant under chromium stress was also observed for both the strains. Both strains enhanced the levels of superoxide dismutase, catalase, peroxidase, total phenolic, and ascorbic acid in tomato plant under different levels of chromium stress conditions. The chromium phytoremediation potential of tomato plant upon inoculation of both the strains was also studied. The results of phytoremediation showed greater chromium accumulation in roots with poor translocation in shoot upon inoculation of Klebsiella sp. while no significant enhancement in chromium uptake by tomato plant was observed on inoculation of Enterobacter sp. compared to control. Thus, these two strains can effectively be used in luxuriant growth of tomato plant under metal stress conditions.


Assuntos
Cromo/toxicidade , Enterobacter/fisiologia , Klebsiella/fisiologia , Lycopersicon esculentum/fisiologia , Poluentes do Solo/toxicidade , Biodegradação Ambiental , Biomassa , Catalase/metabolismo , Enterobacter/metabolismo , Klebsiella/metabolismo , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/microbiologia , Estresse Oxidativo , Desenvolvimento Vegetal , Raízes de Plantas/metabolismo , Superóxido Dismutase/metabolismo
20.
Int J Mol Sci ; 20(24)2019 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-31842360

RESUMO

Drought stress is a major obstacle to agriculture. Although many studies have reported on plant drought tolerance achieved via genetic modification, application of plant growth-promoting rhizobacteria (PGPR) to achieve tolerance has rarely been studied. In this study, the ability of three isolates, including Bacillus amyloliquefaciens 54, from 30 potential PGPR to induce drought tolerance in tomato plants was examined via greenhouse screening. The results indicated that B. amyloliquefaciens 54 significantly enhanced drought tolerance by increasing survival rate, relative water content and root vigor. Coordinated changes were also observed in cellular defense responses, including decreased concentration of malondialdehyde and elevated concentration of antioxidant enzyme activities. Moreover, expression levels of stress-responsive genes, such as lea, tdi65, and ltpg2, increased in B. amyloliquefaciens 54-treated plants. In addition, B. amyloliquefaciens 54 induced stomatal closure through an abscisic acid-regulated pathway. Furthermore, we constructed biofilm formation mutants and determined the role of biofilm formation in B. amyloliquefaciens 54-induced drought tolerance. The results showed that biofilm-forming ability was positively correlated with plant root colonization. Moreover, plants inoculated with hyper-robust biofilm (ΔabrB and ΔywcC) mutants were better able to resist drought stress, while defective biofilm (ΔepsA-O and ΔtasA) mutants were more vulnerable to drought stress. Taken altogether, these results suggest that biofilm formation is crucial to B. amyloliquefaciens 54 root colonization and drought tolerance in tomato plants.


Assuntos
Adaptação Biológica , Bacillus amyloliquefaciens/fisiologia , Biofilmes , Secas , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Estresse Fisiológico , Antioxidantes/metabolismo , Desenvolvimento Vegetal , Raízes de Plantas/microbiologia , Raízes de Plantas/fisiologia , Simbiose
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