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1.
BMC Plant Biol ; 19(1): 371, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31438856

RESUMO

BACKGROUND: Propamocarb (PM) is one of the main pesticides used for controlling cucumber downy mildew. However, due to its volatility and internal absorption, PM can easily form pesticide residues on cucumber fruits that seriously endanger human health and pollute the environment. The breeding of new cucumber varieties with a low abundance of PM residues via genetic methods constitutes an effective strategy for reducing pesticide residues and improving cucumber safety and quality. To help elucidate the molecular mechanism resulting in a low PM residue abundance in cucumber, we used the cucumber cultivar 'D0351' (which has the lowest PM residue content) as the test material and identified genes related to low PM residue abundance through high-throughput tag-sequencing (Tag-Seq). RESULTS: CsMAPEG was constitutively expressed and showed both varietal and organizational differences. This gene was strongly expressed in 'D0351'. The expression levels of CsMAPEG in different cucumber tissues under PM stress were as follows: fruit>leaf>stem>root. CsMAPEG can respond to salicylic acid (SA), gibberellin (GA) and Corynespora cassiicola Wei (Cor) stress and thus plays an important regulatory role in plant responses to abiotic and biological stresses. The PM residue abundance in the fruits of CsMAPEG-overexpressing plants was lower than those found in antisense CsMAPEG plants and wild-type plants at all tested time points. The results revealed that CsMAPEG played a positive role in reducing the PM residue abundance. A CsMAPEG sense construct increased the contents of SOD, POD and GST in cucumber fruits, enhanced the degradation and metabolism of PM in cucumber, and thus effectively reduced the pesticide residue abundance in cucumber fruits. CONCLUSIONS: The expression patterns of CsMAPEG in cucumber cultivars with high and low pesticide residue abundances and a transgenic verification analysis showed that CsMAPEG can actively respond to PM stress and effectively reduce the PM residue abundance in cucumber fruits. The results of this study will help researchers further elucidate the mechanism responsible for a low PM residue abundance in cucumber and lay a foundation for the breeding of new agricultural cucumber varieties with low pesticide residue abundances.


Assuntos
Carbamatos/farmacologia , Cucumis sativus/genética , Fungicidas Industriais/farmacologia , Genes de Plantas , Resíduos de Praguicidas , Clonagem Molecular , Cucumis sativus/efeitos dos fármacos , Cucumis sativus/enzimologia , Cucumis sativus/fisiologia , Perfilação da Expressão Gênica , Vetores Genéticos , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transformação Genética
2.
Plant Dis ; 103(10): 2592-2598, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31347987

RESUMO

The objective of this study was to evaluate fungicide applications, host resistance, and trellising, alone and in combination, as management practices for downy mildew on slicing cucumber. A split-split plot experimental design was used with three and four replications in spring and fall 2017, respectively. The whole-plot treatment was fungicide, four applications of chlorothalonil (Bravo Weather Stik 6SC) alternated with three applications of cyazofamid (Ranman 400SC), or water. Split plots were nontrellised or trellised with four strings supported by stakes. Split-split plots were cultivar Bristol, which is intermediately resistant to downy mildew, or cultivar Speedway, which is susceptible to downy mildew with similar parentage as Bristol. In both seasons, area under the disease progress curve (AUDPC) values were lower with fungicides than water for both cultivars. In the spring, AUDPC for Bristol was lower than for Speedway regardless of fungicide treatment. In the fall, Bristol had a lower AUDPC than Speedway with fungicides, but the AUDPC did not differ between the two cultivars with water. The mean AUDPC for trellised plants (376.2) was lower than for nontrellised plants (434.0; P = 0.007). Fungicide applications increased marketable and total fruit weights in both seasons (P ≤ 0.0002). Marketable weight with fungicides was almost double (93% greater) the marketable weight with water. Marketable weight was 55% greater for Bristol than for Speedway in spring, but yields did not differ between cultivars in fall (season-by-cultivar interaction, P ≤ 0.0003). Because trellising had no effect on marketable yields (P = 0.11), trellising is not recommended for managing downy mildew on slicing cucumber. Of the three management techniques examined, fungicides had the largest effects on disease and yields, followed by cultivar resistance.


Assuntos
Agricultura/métodos , Cucumis sativus , Resistência à Doença , Fungicidas Industriais , Oomicetos , Cucumis sativus/microbiologia , Cucumis sativus/fisiologia , Fungicidas Industriais/farmacologia , Oomicetos/efeitos dos fármacos , Oomicetos/fisiologia , Doenças das Plantas/prevenção & controle
3.
BMC Plant Biol ; 19(1): 243, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31174472

RESUMO

BACKGROUND: Green flesh color, resulting from the accumulation of chlorophyll, is one of the most important commercial traits for the fruits. The genetic network regulating green flesh formation has been studied in tomato, melon and watermelon. However, little is known about the inheritance and molecular basis of green flesh in cucumber. This study sought to determine the main genomic regions associated with green flesh. Three F2 and two BC1 populations derived from the 9110Gt (cultivated cucumber, green flesh color) and PI183967 (wild cucumber, white flesh color) were used for the green flesh genetic analysis. Two F2 populations of them were further employed to do the map construction and quantitative trait loci (QTL) study. Also, a core cucumber germplasms population was used to do the GWAS analysis. RESULTS: We identified three indexes, flesh color (FC), flesh extract color (FEC) and flesh chlorophyll content (FCC) in three environments. Genetic analysis indicated that green flesh color in 9110Gt is controlled by a major-effect QTL. We developed two genetic maps with 192 and 174 microsatellite markers respectively. Two novel inversions in Chr1 were identified between cultivated and wild cucumbers. The major-effect QTL, qgf5.1, was identified using FC, FEC and FCC index in all different environments used. In addition, the same qgf5.1, together with qgf3.1, was identified via GWAS. Further investigation of two candidate regions using pairwise LD correlations, combined with genetic diversity of qgf5.1 in natural populations, it was found that Csa5G021320 is the candidate gene of qgf5.1. Geographical distribution revealed that green flesh color formation could be due to the high latitude, which has longer day time to produce the photosynthesis and chlorophyll synthesis during cucumber domestication and evolution. CONCLUSIONS: We first reported the cucumber green flesh color is a quantitative trait. We detected two novel loci qgf5.1 and qgf3.1, which regulate the green flesh formation in cucumber. The QTL mapping and GWAS approaches identified several candidate genes for further validation using functional genomics or forward genetics approaches. Findings from the present study provide a new insight into the genetic control of green flesh in cucumber.


Assuntos
Cucumis sativus/fisiologia , Estudo de Associação Genômica Ampla , Fenótipo , Pigmentação/genética , Locos de Características Quantitativas/genética , Mapeamento Cromossômico , Cor , Cucumis sativus/genética , Redes Reguladoras de Genes/fisiologia
4.
Plant Physiol Biochem ; 141: 431-445, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31238253

RESUMO

S-adenosylmethionine synthetase (SAMS) catalyzes methionine and ATP to generate S-adenosyl-L-methionine (SAM). In plants, accumulating SAMS genes have been characterized and the majority of them are reported to participate in development and stress response. In this study, two putative SAMS genes (CsSAMS1 and CsSAMS2) were identified in cucumber (Cucumis Sativus L.). They displayed 95% similarity and had a high identity with their homologous of Arabidopsis thaliana and Nicotiana tabacum. The qRT-PCR test showed that CsSAMS1 was predominantly expressed in stem, male flower, and young fruit, whereas CsSAMS2 was preferentially accumulated in stem and female flower. And they displayed differential expression profiles under stimuli, including NaCl, ABA, SA, MeJA, drought and low temperature. To elucidate the function of cucumber SAMS, the full-length CDS of CsSAMS1 was cloned, and prokaryotic expression system and transgenic materials were constructed. Expressing CsSAMS1 in Escherichia coli BL21 (DE3) improved the growth of the engineered strain under salt stress. Overexpression of CsSAMS1 significantly increased MDA content, H2O2 content, and POD activity in transgenic lines under non-stress condition. Under salt stress, however, the MDA content of transgenic lines was lower than that of the wild type, the H2O2 content remained high, the polyamine and ACC synthesis in transgenic lines exhibited a CsSAMS1-expressed dependent way. Taken together, our results suggested that both CsSAMS1 and CsSAMS2 were involved in plant development and stress response, and a proper increase of expression level of CsSAMS1 in plants is benificial to improving salt tolerance.


Assuntos
Cucumis sativus/enzimologia , Cucumis sativus/fisiologia , Metionina Adenosiltransferase/metabolismo , Tolerância ao Sal , Antioxidantes/metabolismo , Arabidopsis/metabolismo , Secas , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/química , Metionina Adenosiltransferase/genética , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Poliaminas/química , Sais , Estresse Mecânico , Estresse Fisiológico/genética , Tabaco/metabolismo
5.
BMC Plant Biol ; 19(1): 164, 2019 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-31029105

RESUMO

BACKGROUND: Circular RNAs (circRNAs) are 3'-5' head-to-tail covalently closed non-coding RNA that have been proved to play essential roles in many cellular and developmental processes. However, no information relate to cucumber circRNAs is available currently, especially under salt stress condition. RESULTS: In this study, we sequenced circRNAs in cucumber and a total of 2787 were identified, with 1934 in root and 44 in leaf being differentially regulated under salt stress. Characteristics analysis of these circRNAs revealed following features: most of them are exon circRNAs (79.51%) and they prefer to arise from middle exon(s) of parent genes (2035/2516); moreover, most of circularization events (88.3%) use non-canonical-GT/AG splicing signals; last but not least, pairing-driven circularization is not the major way to generate cucumber circRNAs since very few circRNAs (18) contain sufficient flanking complementary sequences. Annotation and enrichment analysis of both parental genes and target mRNAs were launched to uncover the functions of differentially expressed circRNAs induced by salt stress. The results showed that circRNAs may be paly roles in salt stress response by mediating transcription, signal transcription, cell cycle, metabolism adaptation, and ion homeostasis related pathways. Moreover, circRNAs may function to regulate proline metabolisms through regulating associated biosynthesis and degradation genes. CONCLUSIONS: The present study identified large number of cucumber circRNAs and function annotation revealed their possible biological roles in response to salt stress. Our findings will lay a solid foundation for further structure and function studies of cucumber circRNAs.


Assuntos
Cucumis sativus/genética , Cucumis sativus/fisiologia , RNA de Plantas/genética , RNA/genética , Estresse Salino/genética , Sequência de Bases , Biomassa , Cucumis sativus/crescimento & desenvolvimento , Éxons/genética , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Redes Reguladoras de Genes , Genes de Plantas , Transporte de Íons , MicroRNAs/genética , MicroRNAs/metabolismo , Anotação de Sequência Molecular , Raízes de Plantas/genética , Raízes de Plantas/fisiologia , RNA/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA de Plantas/metabolismo
6.
Plant Physiol Biochem ; 139: 1-10, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30870715

RESUMO

The role of amorphous silica nanoparticles (SiNPs) in enhancing growth and yield of cucumber under water deficit and salinity stresses was assessed. A field experiment under greenhouse conditions was established using 4 different levels of SiNPs (100, 200, 300 and 400 mg kg-1) and 3 different watering regimes calculated based on crop evapotranspiration (ETc) (100, 85 and 70% of ETc). Electrical conductivity and sodium adsorption ratio of irrigation water were 1.7 dS m-1 and 4.63 respectively. The results revealed that SiNPs improved growth and productivity of cucumber regardless of quantity of supplied water; however, the greatest increase corresponded to irrigating cucumber at the rate of 85% of ETc. Applying SiNPs at rate of 200 mg kg-1 showed the greatest increase specially when cucumber plants received 85% of their ETc causing an increase of 20, 51 and 156% in plant height, chlorophyll and fruit yield, respectively, compared to untreated plants. These increases could be due to alerting nutrient uptake as SiNPs clearly increased contents of nitrogen (by 30%), potassium (by 52, 75 and 41% in root, stem and leaf, respectively) and silicon (by 51, 57, 8 and 78% in root, stem, leaf and fruit, respectively). Otherwise, same treatment reduced sodium uptake by 38, 77 and 38% in root, stem and leaf, respectively; consequently, potassium-sodium ratio increased by 149, 735 and 127% in root, stem and leaf, respectively. The significant role of SiNPs in mitigating water deficit and salinity stresses could be referred to high silicon content found in leaf which regulates water losses via transpiration. Also, high K+ content found in roots of cucumber helps plants to tolerate abiotic stresses as a result of maintaining ion homeostasis and regulating the osmotic balance as well as controlling stomatal opening which helps plants to adapt to salinity and water deficit stresses.


Assuntos
Cucumis sativus/crescimento & desenvolvimento , Nanopartículas , Dióxido de Silício/farmacologia , Produção Agrícola/métodos , Cucumis sativus/efeitos dos fármacos , Cucumis sativus/metabolismo , Cucumis sativus/fisiologia , Desidratação , Relação Dose-Resposta a Droga , Germinação , Potássio/metabolismo , Estresse Salino , Plântula/crescimento & desenvolvimento , Sódio/metabolismo
7.
J Plant Physiol ; 234-235: 154-166, 2019 Mar - Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30818185

RESUMO

This paper investigates the physiological mechanism of the effect of delaying cucumber senescence on protein levels under the experimental model of monoculture and wheat intercropping. We analyzed cucumber roots for differential protein expression, and protein types were identified by core technology of proteomics. 45 differential proteins were identified as being differentially expressed between monoculture and intercropping of wheat, which were involved in carbohydrate metabolism, antioxidant and stress response, growth and development regulation, biological information transfer, and nucleic acid biosynthesis. The results showed the rate of photosynthesis of cucumber was increased under wheat intercropping pattern due to three enzymes being up-regulated. The respiration of cucumber was reduced when five enzymes were down-regulated. The antioxidant and resistant capacity of cucumber was enhanced significantly under wheat intercropping pattern because two enzymes were down-regulated while the activity of four other antioxidant enzymes was up-regulated. Intercropping wheat could delay the senescence of cucumber leaves by increasing the expression of IPT gene, reducing the expression of PAO and ETR2 gene, and inhibiting the expression of Cu/Zn-SOD and GS1 gene in later stages. Two proteins related to growth and development in cucumber were up-regulated, and one was down-regulated, while two proteins related to nucleic acid biosynthesis and chaperonin showed obvious down-regulation under wheat intercropping. Therefore, the growth and development was improved and senescence of cucumber could be delayed. Under intercropping pattern, the fresh weight, chlorophyll content, photosynthetic rate, and peroxidase activity of cucumber plants were higher than those of cucumber monoculture groups. Thus, the senescence of cucumber could be delayed under wheat intercropping by regulating its physiological mechanisms, such as by improving photosynthesis, reducing respiratory consumption, slowing the cell apoptosis rate, and enhancing the antioxidant and resistant capacity significantly, etc.


Assuntos
Cucumis sativus/fisiologia , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Agricultura/métodos , Folhas de Planta/fisiologia , Triticum
8.
Bull Environ Contam Toxicol ; 103(1): 187-192, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30859247

RESUMO

Application of manure resulted in high concentration of antibiotics in soil. Compared to the wide literature on the adverse effects of antibiotics on animals and human beings, the effects on plants are less investigated. In this study, we investigated the growth inhibiting effects of four antibiotics (OTC, DOX, OFL, and ENR) on cucumber, rape and Chinese cabbage using hydroponic methods. Seeds of three vegetable varieties were separately exposed to six concentrations of OTC and DOX (0, 10, 30, 50, 70 and 90 mg/L) and OFL and ENR (0, 20, 40, 80, 160 and 320 mg/L). The growth inhibiting effects of the four antibiotics on three vegetables were different. This study has shown that these antibiotics can induce potential growth inhibiting effects in the natural environment.


Assuntos
Antibacterianos/toxicidade , Brassica/fisiologia , Cucumis sativus/fisiologia , Poluentes do Solo/toxicidade , Animais , Esterco , Solo , Verduras/crescimento & desenvolvimento
9.
Plant Physiol Biochem ; 136: 98-108, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30660678

RESUMO

Heat stress adversely affects plant physiological and metabolic processes and is considered an important constraint on crop growth and productivity in agriculture worldwide. Grafting techniques are capable of mitigating various stresses. Here, compared with self-grafted cucumbers subjected to 42 °C heat stress for 24 h, we found that Momordica-grafted cucumbers exhibited higher cytomembrane thermostability, less photoinhibition reflected by their chlorophyll fluorescence, and a reduction in oxidative stress. To better understand the mechanism, optimized Blue-Native/SDS-PAGE two-dimensional electrophoresis (2-DE) was firstly applied to entire thylakoid membrane of grafted cucumbers, and 25 significantly differential accumulated protein spots were identified by MALDI-TOF/TOF MS analysis. The proteomic analysis revealed that high temperatures suppressed the accumulation of 13 proteins in self-grafted cucumbers, while Momordica rootstock stimulated the accumulation of 12 of these proteins. The transcriptional analysis indicated that grafting onto Momordica significantly increased the expression of genes that encode the photosystem II subunit S (PsbS) and minor light-harvesting complexes (CP24, CP26 and CP29.1), which are closely associated with non-photochemical quenching (NPQ) after heat shock. Immunoblotting for PsbS corroborated the Momordica-induced acceleration of heat dissipation. Taken together, Momordica rootstock alleviated heat-induced photoinhibition by maintaining intracellular redox homeostasis, stabilizing the protein library of the thylakoid membrane and modulating NPQ in the scions.


Assuntos
Cucumis sativus/metabolismo , Momordica charantia/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Tilacoides/metabolismo , Clorofila/metabolismo , Cucumis sativus/fisiologia , Resposta ao Choque Térmico , Momordica charantia/fisiologia , Oxirredução , Estresse Oxidativo , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Plantas/metabolismo , Proteômica
10.
BMC Plant Biol ; 18(1): 268, 2018 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-30400867

RESUMO

BACKGROUND: Cucumbers (Cucumis sativus) are known for their plasticity in sex expression. DNA methylation status determines gene activity but is susceptible to environmental condition changes. Thus, DNA methylation-based epigenetic regulation may at least partially account for the instability of cucumber sex expression. Do temperature and photoperiod that are the two most important environmental factors have equal effect on cucumber sex expression by similar epigenetic regulation mechanism? To answer this question, we did a two-factor experiment of temperature and photoperiod and generated methylome and transcriptome data from cucumber shoot apices. RESULTS: The seasonal change in the femaleness of a cucumber core germplasm collection was investigated over five consecutive years. As a result, 71.3% of the 359 cucumber accessions significantly decreased their femaleness in early autumn when compared with spring. High temperature and long-day photoperiod treatments, which mimic early autumn conditions, are both unfavorable for female flower formation, and temperature is the predominant factor. High temperatures and long-day treatments both predominantly resulted in hypermethylation compared to demethylation, and temperature effect was decisive. The targeted cytosines shared in high-temperature and long-day photoperiod treatment showed the same change in DNA methylation level. Moreover, differentially expressed TEs (DETs) and the predicted epiregulation sites were clustered across chromosomes, and importantly, these sites were reproducible among different treatments. Essentially, the photoperiod treatment preferentially and significantly influenced flower development processes, while temperature treatment produced stronger responses from phytohormone-pathway-related genes. Cucumber AGAMOUS was likely epicontrolled exclusively by photoperiod while CAULIFLOWER A and CsACO3 were likely epicontrolled by both photoperiod and temperature. CONCLUSIONS: Seasonal change of sex expression is a germplasm-wide phenomenon in cucumbers. High temperature and long-day photoperiod might have the same effect on the methylome via the same mechanism of gene-TE interaction but resulted in different epicontrol sites that account for different mechanisms between temperature- and photoperiod-dependent sex expression changes.


Assuntos
Cucumis sativus/genética , Epigênese Genética/genética , Cucumis sativus/fisiologia , Metilação de DNA/genética , Regulação da Expressão Gênica de Plantas/genética , Fotoperíodo , Proteínas de Plantas/genética , Temperatura Ambiente , Transcriptoma/genética
11.
Biosensors (Basel) ; 8(3)2018 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-30201898

RESUMO

In order to exploit plants as environmental biosensors, previous researches have been focused on the electrical signal response of the plants to different environmental stimuli. One of the important outcomes of those researches has been the extraction of meaningful features from the electrical signals and the use of such features for the classification of the stimuli which affected the plants. The classification results are dependent on the classifier algorithm used, features extracted and the quality of data. This paper presents an innovative way of extracting features from raw plant electrical signal response to classify the external stimuli which caused the plant to produce such a signal. A curve fitting approach in extracting features from the raw signal for classification of the applied stimuli has been adopted in this work, thereby evaluating whether the shape of the raw signal is dependent on the stimuli applied. Four types of curve fitting models-Polynomial, Gaussian, Fourier and Exponential, have been explored. The fitting accuracy (i.e., fitting of curve to the actual raw signal) depicted through R-squared values has allowed exploration of which curve fitting model performs best. The coefficients of the curve fit models were then used as features. Thereafter, using simple classification algorithms such as Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA) etc. within the curve fit coefficient space, we have verified that within the available data, above 90% classification accuracy can be achieved. The successful hypothesis taken in this work will allow further research in implementing plants as environmental biosensors.


Assuntos
Algoritmos , Técnicas Biossensoriais/métodos , Potenciais da Membrana , Fenômenos Fisiológicos Vegetais , Transdução de Sinais , Brassica/fisiologia , Cucumis sativus/fisiologia , Lycopersicon esculentum/fisiologia
12.
Plant Physiol Biochem ; 130: 289-302, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30036858

RESUMO

Flavor quality in cucumber is affected by different rootstocks, but the molecular mechanism is largely unclean. To clarify the differences of sugar and aromatic compounds, cucumber (cucumis sativus) fruits from plants of self-grafted (SG) or grafted onto figleaf gourd (Cucurbita ficifolia; G1) or 'Weisheng No.1' rootstock (Cucurbita moschata ⅹCucurbita moschata hybrids; G2) were performed the transcriptome analysis. We obtained 1013 and 920 differentially expressed genes (DEGs) from G1 and G2 compared to SG respectively, in which 453 genes were co-expressed. Functional annotations showed many DEGs were involved in glycolysis/gluconeogenesis metabolism, fructose metabolism and α-Linolenic acid metabolisms, 20 DEGs were selected from the 3 pathways to validate sequencing accuracy by quantitative real-time PCR. The gene relative expression levels were concurrent with RNA-seq results and sugar and aromatic compounds content phenotypes. Moreover, some vital transcript factors and transport proteins were analyzed. These findings indicate that different rootstocks could induce significantly changes in the physiological profiling and transcripts of sugar- and aromatic flavor-related genes. This study provides a novel insight into the molecular mechanisms of fruit quality regulated by candidate genes.


Assuntos
Cucumis sativus/metabolismo , Frutas/metabolismo , Raízes de Plantas/metabolismo , Açúcares/metabolismo , Ácido alfa-Linoleico/metabolismo , Cucumis sativus/genética , Cucumis sativus/fisiologia , Frutose/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Compostos Orgânicos Voláteis/metabolismo
13.
Ying Yong Sheng Tai Xue Bao ; 29(1): 223-230, 2018 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-29692031

RESUMO

Using suspension cultures of cucumber (Cucumis sativus) cultivar Jinyou 35, we investigated the effects of allelochemical stresses induced by Eupatorium adenophorum extracts on root border cells (RBC), and the role of exogenous NO application in alleviation of the damage of root tips exposed to E. adenophorum extracts. The results showed that, 1000 mg·L-1 E. adenophorum extracts had significant damage to the cucumber root tip, resulting in severe tissue damage, exfoliated surface cells and irregular arrangement of inner cells, while those damages could be effectively alleviated by spraying exogenous NO. Compared with the control, E. adenophorum extracts (ZL) markedly reduced RBC numbers and survival rates by 54.5% and 97.2%, respectively, the RBC apoptosis rates were 12.3 times higher, the thicknesses of RBC adhesive layers were increased by 31.4%, and the root cap PME activities were markedly increased. Compared with the ZL treatment, exogenous NO application (ZN) significantly increased RBC numbers and survival rates by 72.4% and 146.0%, respectively, reduced the corresponding RBC apoptosis rates and the thicknesses of RBC adhesive layers by 30.7% and 15.0%, respectively, and inhibited the PME activities by 14.3% upon treatment for 72 hours. Our findings revealed that E. adenophorum extracts showed toxic effects on the cucumber RBC, resulting in cell apoptosis, abolishment of the RBC protection on root tips, and the destruction of root tip structure. Exogenous NO application, to some extent, could prevent the root tip and RBC from cell damage caused by E. adenophorum extracts.


Assuntos
Ageratina/química , Cucumis sativus/fisiologia , Feromônios , Raízes de Plantas/citologia , Raízes de Plantas/crescimento & desenvolvimento
14.
Plant Mol Biol ; 97(1-2): 1-21, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29633167

RESUMO

KEY MESSAGE: The mechanism of exogenous Spd-induced Ca(NO3)2 stress tolerance in cucumber was studied by proteomics and physiological analyses. Protein-protein interaction network revealed 13 key proteins involved in Spd-induced Ca(NO3)2 stress resistance. Ca(NO3)2 stress is one of the major reasons for secondary salinization that limits cucumber plant development in greenhouse. The conferred protective role of exogenous Spd on cucumber in response to Ca(NO3)2 stress cues involves changes at the cellular and physiological levels. To investigate the molecular foundation of exogenous Spd in Ca(NO3)2 stress tolerance, a proteomic approach was performed in our work. After a 9 days period of Ca(NO3)2 stress and/or exogenous Spd, 71 differential protein spots were confidently identified. The resulting proteins were enriched in seven different categories of biological processes, including protein metabolism, carbohydrate and energy metabolism, ROS homeostasis and stress defense, cell wall related, transcription, others and unknown. Protein metabolism (31.2%), carbohydrate and energy metabolism (15.6%), ROS homeostasis and stress defense (32.5%) were the three largest functional categories in cucumber root and most of them were significantly increased by exogenous Spd. The Spd-responsive protein interaction network revealed 13 key proteins, whose accumulation changes could be critical for Spd-induced resistance; all 13 proteins were upregulated by Spd at transcriptional and protein levels in response to Ca(NO3)2 stress. Furthermore, accumulation of antioxidant enzymes, non-enzymatic antioxidant and polyamines, along with reduction of H2O2 and MDA, were detected after exogenous Spd application during Ca(NO3)2 stress. The results of these proteomic and physiological analyses in cucumber root may facilitate a better understanding of the underlying mechanism of Ca(NO3)2 stress tolerance mediated by exogenous Spd.


Assuntos
Compostos de Cálcio/metabolismo , Cucumis sativus/fisiologia , Nitratos/metabolismo , Espermidina/fisiologia , Proteínas de Plantas/metabolismo , Raízes de Plantas/fisiologia , Proteômica , Plântula/fisiologia , Estresse Fisiológico
15.
J Plant Physiol ; 224-225: 112-120, 2018 May - Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29617631

RESUMO

Raffinose family oligosaccharides (RFOs) accumulate under stress conditions in many plants and have been suggested to act as stress protectants. To elucidate the metabolic process of RFOs under cold stress, levels of RFOs, and related carbohydrates, the expression and activities of main metabolic enzymes and their subcellular compartments were investigated during low-temperature treatment and during the recovery period in cucumber leaves. Cold stress induced the accumulation of stachyose in vacuoles, galactinol in vacuoles and cytosol, and sucrose and raffinose in vacuoles, cytosol, and chloroplasts. After cold stress removal, levels of these sugars decreased gradually in the respective compartments. Among four galactinol synthase genes (CsGS), CsGS1 was not affected by cold stress, while the other three CsGSs were up-regulated by low temperature. RNA levels of acid-α-galactosidase (GAL) 3 and alkaline-α-galactosidase (AGA) 2 and 3, and the activities of GAL and AGA, were up-regulated after cold stress removal. GAL3 protein and GAL activity were exclusively located in vacuoles, whereas AGA2 and AGA 3 proteins were found in cytosol and chloroplasts, respectively. The results indicate that RFOs, which accumulated during cold stress in different subcellular compartments in cucumber leaves, could be catabolized in situ by different galactosidases after stress removal.


Assuntos
Temperatura Baixa , Cucumis sativus/fisiologia , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Rafinose/metabolismo , alfa-Galactosidase/genética , Cucumis sativus/enzimologia , Folhas de Planta/enzimologia , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Estresse Fisiológico , alfa-Galactosidase/metabolismo
16.
Biochem Biophys Res Commun ; 499(2): 307-313, 2018 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-29574158

RESUMO

Cucumber is an important vegetable with indeterminate growth habit which is beneficial to its yield. In this study, we cloned the TFL1 homolog CsTFL1b in cucumber. CsTFL1b shares highly sequence similarity to TFL1 from Arabidopsis and has conservative histidine amino acid residue which is necessary for TFL1 function. However, phylogenetic analysis suggested that cucurbits TFL1s (CsTFL1b of cucumber and CmTFL1 of melon) formed a subclade which is far from the AtTFL1 in Arabidopsis or CEN in Antirrhinum. CsTFL1b was highest expressed in male flower but barely expressed in SAM which was different from TFL1 in Arabidopsis with highly transcription accumulation in SAM and CsTFL1b was located in nucleus and cytoplasm. Upon ectopic expression of CsTFL1b in Arabidopsis, the flowering time of transgenic plants was significantly delayed in both wild type and tfl1-11 mutant background but the terminal flower phenotype of tfl1-11 mutant was partially rescued. These results may underlie the discrepant function of CsTFL1b in cucumber from that in Arabidopsis.


Assuntos
Cucumis sativus/anatomia & histologia , Cucumis sativus/fisiologia , Inflorescência/anatomia & histologia , Inflorescência/fisiologia , Proteínas de Plantas/metabolismo , Sequência de Aminoácidos , Arabidopsis/genética , Clonagem Molecular , Cucumis sativus/genética , Regulação da Expressão Gênica de Plantas , Inflorescência/genética , Mutação/genética , Filogenia , Proteínas de Plantas/química , Plantas Geneticamente Modificadas , Homologia de Sequência de Aminoácidos , Fatores de Tempo
17.
Exp Appl Acarol ; 75(1): 41-53, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29600387

RESUMO

The plant stress hypothesis posits that a herbivore's reproductive success increases when it feeds on stressed plants, while the plant vigor hypothesis predicts that a herbivore preferentially feeds on more vigorous plants. We examined these opposing hypotheses by growing spider mites (Tetranychus urticae) on the leaves of stressed and healthy (vigorous) cucumber plants. Host plants were grown under controlled conditions at low, moderate, and high concentrations of NaCl (to induce salinity stress), at low, moderate, and high fertilizer concentrations (to support growth), and without these additions (control). The effects of these treatments were evaluated by measuring fresh and dry plant biomass, carotenoid and chlorophyll content, antioxidant enzyme activity, and concentrations of PO43-, K+, and Na+ in plant tissues. The addition of low concentrations of fertilizer increased dry mass, protein, and carotenoid content relative to controls, suggesting a beneficial effect on plants. The highest NaCl treatment (2560 mg L-1) resulted in increased Na+ and protein content relative to control plants, as well as reduced PO43-, K+, and chlorophyll levels and reduced catalase and ascorbate peroxidase enzyme activity levels. Analysis of life table data of T. urticae mites raised on leaves from the aforementioned plant groups showed the intrinsic rate of increase (r) for mites was 0.167 day-1 in control specimens, 0.125 day-1 for mites reared on plants treated with a moderate concentration of fertilizer (10 mL L-1), and was highest (0.241 day-1) on plants grown under moderate salinity conditions (1920 mg L-1 NaCl). Reproductive success of T. urticae did not differ on plants watered with a moderate concentration of NaCl or a high concentration of fertilizer. The moderately-stressed plants formed a favorable environment for the development and reproduction of spider mites, supporting the plant stress hypothesis.


Assuntos
Cucumis sativus/fisiologia , Fertilizantes/análise , Salinidade , Tetranychidae/fisiologia , Animais , Feminino , Masculino , Crescimento Demográfico , Reprodução
18.
Plant Cell Physiol ; 59(5): 930-945, 2018 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29415202

RESUMO

The NAC transcription factors play vital roles in responding to drought stress in plants; however, the molecular mechanisms remain largely unknown in cucumber. Suppression of CsATAF1 via RNA interference (RNAi) weakened drought stress tolerance in cucumber due to a higher water loss rate in leaves, a higher level of hydrogen peroxide (H2O2) and superoxide radicals (O2·-), increased malondialdehyde (MDA) content, lower Fv/Fm ratios and lower antioxidant enzyme activity. The analysis of root length and stomatal apertures showed that CsATAF1-RNAi cucumber plants were less responsive to ABA. In contrast, CsATAF1-overexpression (OE) plants showed increased drought stress tolerance and sensitivity to ABA. Quantitative PCR (qPCR) analysis showed that expression of several stress-responsive genes was significantly up-regulated in CsATAF1-OE transformants and down-regulated in CsATAF1-RNAi transformants. CsABI5, CsCu-ZnSOD and CsDREB2C were verified as direct target genes of CsATAF1. Yeast one-hybrid analysis and electrophoretic mobility shift assay (EMSA) further substantiated that CsATAF1 bound to the promoters of CsABI5, CsCu-ZnSOD and CsDREB2C. Transient expression in tobacco leaves and cucumber protoplasts showed that CsATAF1 directly up-regulated the expression of CsABI5, CsCu-ZnSOD and CsDREB2C. Our results demonstrated that CsATAF1 functioned as a positive regulator in response to drought stress by an ABA-dependent pathway and decreasing reactive oxygen species (ROS) accumulation in cucumber.


Assuntos
Ácido Abscísico/farmacologia , Adaptação Fisiológica , Cucumis sativus/fisiologia , Secas , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico , Adaptação Fisiológica/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Cucumis sativus/genética , Cucumis sativus/crescimento & desenvolvimento , Depuradores de Radicais Livres/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas , Germinação/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Transporte Proteico/efeitos dos fármacos , Interferência de RNA , Análise de Sequência de DNA , Estresse Fisiológico/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/genética
19.
Plant Sci ; 267: 55-64, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29362099

RESUMO

Nitrate reductase (NR) mainly reduces nitrate to nitrite. However, in certain conditions it can reduce nitrite to NO. In plants, a plasma membrane-associated form of NR (PM-NR) is present. It produces NO2- for nitrite NO/reductase (Ni-NOR), which can release NO into the apoplastic space. The effect of 50 mM NaCl on NO formation and the involvement of NR in NO biosynthesis were studied in cucumber seedling roots under salt stress. In salt-stressed roots, the amount of NO was higher than in control. The application of tungstate abolished the increase of NO level in stressed roots, indicating that NR was responsible for NO biosynthesis under the test conditions. The involvement of other molybdoenzymes was excluded using specific inhibitors. Furthermore, higher cNR and PM-NR activities were observed in NaCl-treated roots. The increase in NR activity was due to the stimulation of CsNR genes expression and posttranslational modifications, such as enzyme dephosphorylation. This was confirmed by Western blot analysis. Moreover, the increase of nitrite tissue level in short-term stressed roots and the nitrite/nitrate ratio, with a simultaneous decrease of nitrite reductase (NiR) activity, in both short- and long-term stressed roots, could promote the production of NO by NR in roots under salt stress.


Assuntos
Cucumis sativus/fisiologia , Nitrato Redutase/genética , Óxido Nítrico/biossíntese , Proteínas de Plantas/genética , Cloreto de Sódio/farmacologia , Membrana Celular/metabolismo , Cucumis sativus/genética , Citoplasma/metabolismo , Nitrato Redutase/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Estresse Fisiológico
20.
Plant Cell Environ ; 41(1): 148-159, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28548208

RESUMO

Absorbed light energy is converted into excitation energy. The excitation energy is distributed to photosystems depending on the wavelength and drives photochemical reactions. A non-destructive, mechanistic and quantitative method for estimating the fraction of the excitation energy distributed to photosystem II (f) was developed. For the f values for two simultaneously provided actinic lights (ALs) with different spectral distributions to be estimated, photochemical yields of the photosystems were measured under the ALs and were then fitted to an electron transport model assuming the balance between the electron transport rates through the photosystems. For the method to be tested using leaves with different properties in terms of the long-term and short-term acclimation (adjustment of photosystem stoichiometry and state transition, respectively), the f values for red and far-red light (R and FR) were estimated in leaves grown (~1 week) under white light without and with supplemental FR and adapted (~10 min) to R without and with supplemental FR. The f values for R were clearly greater than those for FR and those of leaves grown with and adapted to supplemental FR tended to be higher than the controls. These results are consistent with previous studies and therefore support the validity of the proposed method.


Assuntos
Cucumis sativus/fisiologia , Luz , Modelos Biológicos , Fotossíntese , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Cucumis sativus/efeitos da radiação , Transporte de Elétrons/efeitos da radiação , Fótons , Fotossíntese/efeitos da radiação , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Teoria Quântica , Fatores de Tempo
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