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1.
Plants (Basel) ; 8(11)2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31698739

RESUMO

Limited information is available on the cold acclimation of non-heading Chinese cabbage (NHCC) under low temperatures. In this study, the isobaric tags for relative and absolute quantification (iTRAQ) were used to illustrate the molecular machinery of cold acclimation. Compared to the control (Cont), altogether, 89 differentially expressed proteins (DEPs) were identified in wucai leaves responding to low temperatures (LT). Among these proteins, 35 proteins were up-regulated ((and 54 were down-regulated). These differentially expressed proteins were categorized as having roles in carbohydrate metabolism, photosynthesis and energy metabolism, oxidative defense, amino acid metabolism, metabolic progress, cold regulation, methylation progress, and signal transduction. The fructose, glucose, and sucrose were dramatically increased in response to cold acclimation. It was firstly reported that aspartate, serine, glutamate, proline, and threonine were significantly accumulated under low temperatures. Results of quantitative real-time PCR analysis of nine DEPs displayed that the transcriptional expression patterns of six genes were consistent with their protein expression abundance. Our results demonstrated that wucai acclimated to low temperatures through regulating the expression of several crucial proteins. Additionally, carbohydrate and amino acid conversion played indispensable and vital roles in improving cold assimilation in wucai.

2.
BMC Genomics ; 20(1): 810, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31694527

RESUMO

BACKGROUND: Brassinosteroids (BRs) have a positive effect on many processes during plant growth and development, and in response to various abiotic stressors. Low-temperature (LT) stress constricts the geographic distribution, growth, and development of wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen). However, there is little information on the global gene expression of BRs under LT stress in wucai. In this study, the molecular roles of 24-epibrassinolide (EBR) after exogenously application, were explored by RNA sequencing under LT conditions. RESULTS: According to the Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, photosynthesis was significantly enriched after spraying EBR under LT. The transcripts encoding the photosystem II (PSII) oxygen-evolving enhancer protein, photosystem I (PSI) subunit, light-harvesting chlorophyll protein complexes I and II, and ferredoxin were up-regulated after the application of EBR. Transcripts encoding several key enzymes involved in chlorophyll biosynthesis were also up-regulated, accompanied by significant differences in the contents of 5-aminolevulinic acid (ALA), porphobilinogen (PBG), protoporphyrin IX (Proto IX), Mg-protoporphyrin IX (Mg-proto IX), protochlorophyllide (Pchl), and photosynthetic pigments. Notably, transcriptional and physiological analyses revealed that under LT stress, plant responses to EBR involved a major reorientation of photosynthesis, as well as porphyrin and chlorophyll metabolism. CONCLUSION: This study explored the role of EBR as an LT stress tolerance mechanism in wucai. At the transcription level, LT tolerance manifests as an enhancement of photosynthesis, and the amelioration of porphyrin and chlorophyll metabolism.

3.
Int J Mol Sci ; 20(20)2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31623239

RESUMO

Light is one of the most important abiotic factors for most plants, which affects almost all growth and development stages. In this study, physiological indicators suggest that the application of exogenous Ca2+ improves photosynthesis and changes phytohormone levels. Under weak light, photosynthetic parameters of the net photosynthetic rate (PN), stomatal conductance (Gs), and transpiration rate (Tr) decreased; the antioxidation systems peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) reduced; the degrees of malondialdehyde (MDA), H2O2, and superoxide anion (O2-) free radical damage increased; while exogenous Ca2+ treatment was significantly improved. RNA-seq analysis indicated that a total of 13,640 differently expressed genes (DEGs) were identified and 97 key DEGs related to hormone, photosynthesis, and calcium regulation were differently transcribed. Gene ontology (GO) terms and Kyoto encyclopedia of genes and genomes (KEGG) pathway analyses, plant hormone signal transduction, photosynthesis, carbon metabolism, and phenylpropanoid biosynthesis were significantly enriched. Additionally, quantitative real-time PCR (qRT-PCR) analysis confirmed some of the key gene functions in response to Ca2+. Overall, these results provide novel insights into the complexity of Ca2+ to relieve injuries under weak light, and they are helpful for potato cultivation under weak light stress.

4.
Int J Mol Sci ; 20(15)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374822

RESUMO

The genotype WS-1, previously identified from novel wucai germplasm, is tolerant to both low-temperature (LT) and high-temperature (HT) stress. However, it is unclear which signal transduction pathway or acclimation mechanisms are involved in the temperature-stress response. In this study, we used the proteomic method of tandem mass tag (TMT) coupled with liquid chromatography-mass spectrometry (LC-MS/MS) to identify 1022 differentially expressed proteins (DEPs) common to WS-1, treated with either LT or HT. Among these 1022 DEPs, 172 were upregulated in response to both LT and HT, 324 were downregulated in response to both LT and HT, and 526 were upregulated in response to one temperature stress and downregulated in response to the other. To illustrate the common regulatory pathway in WS-1, 172 upregulated DEPs were further analyzed. The redox homeostasis, photosynthesis, carbohydrate metabolism, heat-shockprotein, and chaperones and signal transduction pathways were identified to be associated with temperature stress tolerance in wucai. In addition, 35S:BcccrGLU1 overexpressed in Arabidopsis, exhibited higher reduced glutathione (GSH) content and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio and less oxidative damage under temperature stress. This result is consistent with the dynamic regulation of the relevant proteins involved in redox homeostasis. These data demonstrate that maintaining redox homeostasis is an important common regulatory pathway for tolerance to temperature stress in novel wucai germplasm.


Assuntos
Brassica/fisiologia , Termotolerância , Brassica/genética , Resposta ao Choque Frio , Regulação da Expressão Gênica de Plantas , Resposta ao Choque Térmico , Homeostase , Oxirredução , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Mapas de Interação de Proteínas , Proteômica
5.
J Proteome Res ; 18(6): 2478-2492, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-31038978

RESUMO

Chlorophyll is a vital photosynthetic pigment that plays a key role in plant development, participating in light energy capture and energy conversion. In this study, a novel wucai ( Brassica campestris L.) germplasm with green outer leaves and yellow inner leaves at the adult stage (W7-2) was used to examine chlorophyll metabolism response to cold acclimation. A green leaf wucai genotype without leaf color changes named W7-1 was selected as the control to evaluate the chlorophyll metabolism changes of W7-2. Compared to W7-1, the contents of chlorophyll a (Chl a) and chlorophyll b (Chl b) in W7-2 were significantly reduced at five developmental stages (13, 21, 29, 37, and 45 days after planting (DAP)). An iTRAQ-based quantitative proteomic analysis was carried out at 21 and 29 DAP according to the leaf color changes in both of genotypes. 1409 proteins were identified, while 218 of them displayed differential accumulations between W7-2 and W7-1 during the two developmental stages. The differentially expressed proteins (DEPs) mainly assigned to chlorophyll biosynthesis, photosynthesis, carbohydrate metabolism, ribosome metabolism and posttranslational modification. Among these DEPs, NADPH-protochlorophyllide oxidoreductase (PORB) and Mg-protoporphyrin IX chelatase 1 (CHLI1) were the key enzymes participating in chlorophyll (Chl) biosynthesis, which was down-regulated at 21 DAP and up-regulated at 29 DAP in W7-2 compared with W7-1, respectively. The expression analysis of genes of three subunits of Mg-chelatase ( CHLI1, CHLD, and CHLH), Genomes Uncoupled 4 ( GUN4), and Thioredoxin ( TRX3) associated with chlorophyll metabolism also displayed significant down-regulation in W7-2. In particular, PORB showed significant up-regulation in W7-2, significantly affecting chlorophyll biosynthesis. Additionally, differences in chlorophyll metabolism between W7-2 and W7-1 were in terms of altered photosynthesis, carbohydrate, and energy metabolism. We found that the transcription levels of most photosynthesis proteins showed significantly lower levels, and the genes expression level, associated with carbohydrate and energy metabolism, were lower in W7-2 than in W7-1. Therefore, the present study results help understand the physiological and molecular mechanisms underlying leaf coloring responding to cold acclimation.

6.
Plant Cell Rep ; 38(5): 577-586, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30758711

RESUMO

KEY MESSAGE: We developed a novel Agrobacterium-mediated anther transformation for Wucai in planta, and in this procedure, the male germ line was the predominant target. Wucai (Brassica campestris L.), a variant of non-heading Chinese cabbage, is widely cultured in China and only improved by classic breeding methods. Here, a novel and efficient in planta Agrobacterium-mediated anther transformation method is developed based on the optimization of several factors that affect anther transformation. After optimization, transformation with the manual pollination application led to increased transient GUS expression in anthers (reaching 91.59%) and the transformation efficacies in planta (0.59-1.56% for four commercial cultivars). The stable integration and inheritance of the transgenes were further examined by molecular and genetic analyses. Three T2 transgenic lines presented a segregation ratio of 3:1, which was consistent with the Mendelian feature of a single dominant gene. In addition, the GUS histochemical assay and genetic crossing analysis revealed that the male germ line was the predominant target in this transformation. This optimized transformation system could provide a useful tool for both the improvement of cultivar qualities and investigation of functional genes in Wucai.


Assuntos
Agrobacterium tumefaciens/genética , Brassica/genética , Brassica/fisiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/fisiologia , Transformação Genética/genética , Brassica/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Polinização/genética , Polinização/fisiologia
7.
BMC Genomics ; 19(1): 908, 2018 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-30541424

RESUMO

BACKGROUND: Wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen) is a variant of nonheading Chinese cabbage (Brassica campestris L.), which is one of the major vegetables in China. Cytoplasmic male sterility (CMS) has been used for Wucai breeding in recent years. However, the underlying molecular mechanism of Wucai CMS remains unclear. In this study, the phenotypic and cytological features of Wucai CMS were observed by anatomical analysis, and a comparative transcriptome analysis was carried out to identify genes related to male sterility using Illumina RNA sequencing technology (RNA-Seq). RESULTS: Microscopic observation demonstrated that tapetum development was abnormal in the CMS line, which failed to produce fertile pollen. Bioinformatics analysis detected 4430 differentially expressed genes (DEGs) between the fertile and sterile flower buds. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to better understand the functions of these DEGs. Among the DEGs, 35 genes (53 DEGS) were implicated in anther and pollen development, and 11 genes were involved in pollen cell wall formation and modification; most of these showed downregulated expression in sterile buds. In addition, several genes related to tapetum development (A6, AMS, MS1, MYB39, and TSM1) and a few genes annotated to flowering (CO, AP3, VIN3, FLC, FT, and AGL) were detected and confirmed by qRT-PCR as being expressed at the meiosis, tetrad, and uninucleate microspore stages, thus implying possible roles in specifying or determining the fate and development of the tapetum, male gametophyte and stamen. Moreover, the top four largest transcription factor families (MYB, bHLH, NAC and WRKY) were analyzed, and most showed reduced expression in sterile buds. These differentially expressed transcription factors might result in abortion of pollen development in Wucai. CONCLUSION: The present comparative transcriptome analysis suggested that many key genes and transcription factors involved in anther development show reduced gene expression patterns in the CMS line, which might contribute to male sterility in Wucai. This study provides valuable information for a better understanding of CMS molecular mechanisms and functional genome studies in Wucai.


Assuntos
Brassica/genética , Perfilação da Expressão Gênica/métodos , Genes de Plantas , Infertilidade das Plantas/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Hibridização Genômica Comparativa , Flores/genética , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Melhoramento Vegetal , Proteínas de Plantas/genética , RNA de Plantas/química , RNA de Plantas/isolamento & purificação , RNA de Plantas/metabolismo , Análise de Sequência de RNA
8.
Vaccine ; 35(52): 7250-7255, 2017 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-29153585

RESUMO

The reported coverage with two doses of the measles vaccine (MCV) in Shaanxi Province, China, is greater than 95%, but the measles incidence over the whole province remains high. Cross-sectional serological surveys of measles antibodies in Shaanxi Province were conducted in 2016 to assess the population's immunity. The measles IgG levels were measured in serum samples using ELISA. The geometric means concentration (GMC) levels and seroprevalence rates with 95% CIs were calculated by region, gender, and age. A total of 3574 serum samples were collected from participants aged from 2 months to 49 years. The GMC of measles antibodies was 471.3 mIU/ml (95% CI: 445.9-498.2 mIU/ml), and the seroprevalence was only 85.9% (95% CI: 84.8-87.1%). A significant difference in the GMC (P < .05) but not the seroprevalence (P > .05) was observed among the 3 regions. The report measles incidences were high in individuals aged 0-7 months (33.2/100 000) and 8-17 months (26.8/100 000). Although both measles immunity (90.7%) and MCV coverage (89.7%) were low in children aged 8-17 months, the measles seroprevalence in adults was high at greater than 90%. These results revealed that further actions may be taken to increase vaccination coverage in children aged 8 months to 5 years over the whole province and teenagers in the south region. In particular, timely administration of the first MCV dose should be emphasized to prevent measles epidemics in children aged 8-17 months. Vaccination strategies may be varied by age and region.


Assuntos
Anticorpos Antivirais/sangue , Suscetibilidade a Doenças/imunologia , Sarampo/imunologia , População , Estudos Soroepidemiológicos , Adolescente , Adulto , Criança , Pré-Escolar , China/epidemiologia , Estudos Transversais , Feminino , Humanos , Imunoglobulina G/sangue , Incidência , Lactente , Recém-Nascido , Masculino , Programas de Rastreamento/métodos , Sarampo/sangue , Sarampo/prevenção & controle , Vacina contra Sarampo/administração & dosagem , Pessoa de Meia-Idade , Vacinação/estatística & dados numéricos , Cobertura Vacinal , Adulto Jovem
9.
J Plant Physiol ; 188: 29-36, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26398630

RESUMO

2,4-Epibrassinolide (EBL) is a plant hormone that plays a pivotal role in regulation of plants growth and development processes under abiotic stress. The investigation was carried out to study the effect of EBL on mineral nutrients uptake and distribution with ion element analysis and X-ray microanalysis in cucumber seedlings (Cucumis sativus L. cv. Jinyou No.4) under 80 mM Ca(NO3)2 stress. Our study found EBL significantly alleviated the inhibitory of P, K, Na, Mg, Fe, Mn, or Cl uptake in shoot or root by Ca(NO3)2 stress. Under Ca(NO3)2 stress, X-ray microanalysis showed that high levels of Ca by EBL treatment accumulated in the epidermal cells of root and gradually decreased from epidermal cells to stellar parenchyma. K(+) levels were restored in different cross section of roots and high K(+) level mostly accumulated in stellar parenchyma. The results of Ca(2+) ultra-structural localization showed Ca(2+) particles of antimonite precipitate by EBL were partly decreased in mesophyll and root cells, and Ca(2+) precipitate distributed in intercellular spaces again. Increased Ca(2+)-ATPase activity and ATP content by EBL were also contributed to extrude excess Ca(2+) from the cytoplasm. These results suggested that EBL could alleviate the ion damage from excess Ca(2+) through regulating mineral nutrients uptake and distribution.


Assuntos
Brassinosteroides/metabolismo , Compostos de Cálcio/metabolismo , Cucumis sativus/fisiologia , Homeostase , Nitratos/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Esteroides Heterocíclicos/metabolismo , Estresse Fisiológico , Trifosfato de Adenosina/metabolismo , Cálcio/metabolismo , ATPases Transportadoras de Cálcio/metabolismo , Íons/metabolismo , Raízes de Plantas/fisiologia , Brotos de Planta/fisiologia
10.
Sci Rep ; 5: 11391, 2015 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-26304855

RESUMO

Hypoxia induces plant stress, particularly in cucumber plants under hydroponic culture. In plants, calcium is involved in stress signal transmission and growth. The ultimate goal of this study was to shed light on the mechanisms underlying the effects of exogenous calcium on the mitochondrial antioxidant system, the activity of respiratory metabolism enzymes, and ion transport in cucumber (Cucumis sativus L. cv. Jinchun No. 2) roots under hypoxic conditions. Our experiments revealed that exogenous calcium reduces the level of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in mitochondria under hypoxia. Exogenous calcium also enhances the accumulation of enzymes involved in glycolysis and the tricarboxylic acid (TCA) cycle. We utilized fluorescence and ultrastructural cytochemistry methods to observe that exogenous calcium increases the concentrations of Ca(2+) and K(+) in root cells by increasing the activity of plasma membrane (PM) H(+)-ATPase and tonoplast H(+)-ATPase and H(+)-PPase. Overall, our results suggest that hypoxic stress has an immediate and substantial effect on roots. Exogenous calcium improves metabolism and ion transport in cucumber roots, thereby increasing hypoxia tolerance in cucumber.


Assuntos
Cálcio/farmacocinética , Cucumis sativus/metabolismo , Hidrolases/metabolismo , Mitocôndrias/metabolismo , Oxigênio/metabolismo , Raízes de Plantas/metabolismo , Hipóxia Celular/fisiologia , Respiração Celular/fisiologia , Transporte de Íons/fisiologia , Estresse Oxidativo/fisiologia , Espécies Reativas de Oxigênio/metabolismo
11.
Plant Physiol Biochem ; 63: 209-16, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23291654

RESUMO

The effects of exogenous spermine (Spm) on plant growth, chlorophyll fluorescence, ultrastructure and anti-oxidative metabolism of chloroplasts were investigated in Cucumis sativus L. under NaCl stress. Salt stress significantly reduced plant growth, chlorophylls content and F(v)/F(m). These changes could be alleviated by foliar spraying with Spm. Salt stress caused an increase in malondialdehyde (MDA) content and superoxide anion [Formula: see text] generation rate in chloroplasts. Application of Spm significantly increased activities of superoxidase dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), and ascorbate peroxidase (APX, EC 1.11.1.11) which decreased the levels of [Formula: see text] and MDA in the salt-stressed chloroplasts. Salt stress decreased the activities of dehydroascorbate reductase (DHAR, EC 1.8.5.1) and glutathione reductase (GR, EC 1.6.4.2) in the chloroplasts and reduced the contents of dehydroascorbate (DAsA) and glutathione (GSH), but increased monodehydroascorbate reductase (MDAR, EC 1.6.5.4) activity. On the other hand, Spm significantly increased the activities of antioxidant enzymes and levels of antioxidants in the salt-stressed chloroplasts. Further analysis of the ultrastructure of chloroplasts indicated that salinity induced destruction of the chloroplast envelope and increased the number of plastoglobuli with aberrations in thylakoid membranes. However, Spm application to salt-stressed plant leaves counteracted the adverse effects of salinity on the structure of the photosynthetic apparatus. These results suggest that Spm alleviates salt-induced oxidative stress through regulating antioxidant systems in chloroplasts of cucumber seedlings, which is associated with an improvement of the photochemical efficiency of PSII.


Assuntos
Antioxidantes/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Cucumis sativus/efeitos dos fármacos , Cucumis sativus/metabolismo , Cloreto de Sódio/farmacologia , Espermina/farmacologia , Cloroplastos/efeitos dos fármacos
12.
Plant Physiol Biochem ; 61: 29-35, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23031845

RESUMO

Ca(NO(3))(2) accumulation is a major factor that limits greenhouse production in China. The present investigation was carried out to study the effect of 24-epibrassinolide (EBL) on nitrogen metabolism (including contents of NO(3)(-), NH(4)(+) and amino acids and related enzymes activities) in cucumber seedlings (Cucumis sativus L. cv. Jinyou No. 4) under 80 mM Ca(NO(3))(2) stress. This study found that exogenous EBL significantly reduced the accumulation of NO(3)(-) and NH(4)(+) by Ca(NO(3))(2), and enhanced the inactivated enzymes activities involved in the nitrogen metabolism. In addition, EBL alleviated the inhibition of photosynthesis nitrogen-use efficiency by Ca(NO(3))(2). Increased total amino acids by EBL under stress increased the precursor of proteins biosynthesis, thus promoting the biosynthesis nitrogen containing compounds. The presence of Ca(NO(3))(2) increased polyamines level, which might result from the increased content of free putrescine that is harmful to plant growth. However, exogenous EBL induced a further increase in total polyamines. The increase is likely caused by the elevated contents of conjugated and bound forms of polyamines. In summary, exogenously EBL compensated for the damage/losses by Ca(NO(3))(2) stress to some extent through the regulation of nitrogen metabolism and metabolites.


Assuntos
Brassinosteroides/farmacologia , Compostos de Cálcio/efeitos adversos , Cucumis/efeitos dos fármacos , Nitratos/efeitos adversos , Nitrogênio/metabolismo , Reguladores de Crescimento de Planta/farmacologia , Proteínas de Plantas/biossíntese , Esteroides Heterocíclicos/farmacologia , Estresse Fisiológico , Aminoácidos/metabolismo , Compostos de Cálcio/metabolismo , Cucumis/metabolismo , Cucumis/fisiologia , Nitratos/metabolismo , Fotossíntese/efeitos dos fármacos , Poliaminas/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , Putrescina/metabolismo , Compostos de Amônio Quaternário/metabolismo , Sais/efeitos adversos , Sais/metabolismo
13.
Photosynth Res ; 112(3): 205-14, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22864978

RESUMO

The effects of 0.1 µM 24-epibrassinolide (EBL) on plant growth (plant height, leaf area, fresh weight, and dry weight), chlorophyll content, photosynthetic characteristics, antioxidant enzymes, and chloroplast ultrastructure were investigated using cucumber seedlings (Cucumis sativus L. cv. Jinyou No. 4) with 80 mM Ca(NO(3))(2) to induce stress. The presence of Ca(NO(3))(2) caused significant reductions in net photosynthetic rate (P(N)), stomatal conductance (Gs), intercellular CO(2) concentration (Ci), and transpiration rate (Tr) of leaves. In addition, Ca(NO(3))(2) markedly reduced the chlorophyll content and inhibited photochemical activity, including the actual photochemical efficiency (ΦPSII). In contrast, EBL increased the chlorophyll content, especially chlorophyll b, and minimized the harmful effects on photosynthesis caused by the Ca(NO(3))(2). The application of EBL to the plants subjected to Ca(NO(3))(2)-enhanced photochemical activity. EBL protected the photosynthetic membrane system from oxidative damage due to up-regulating the capacity of the antioxidant systems. Microscopic analyses revealed that Ca(NO(3))(2) affected the structure of the photosynthetic apparatus and membrane system and induced damage of granal thylakoid layers, while EBL recovered the typical shape of chloroplasts and promoted the formation of grana. Taken together, EBL compensated for damage/losses by Ca(NO(3))(2) due to the regulation of photosynthetic characteristics and the antioxidant system.


Assuntos
Antioxidantes/metabolismo , Brassinosteroides/farmacologia , Cloroplastos/efeitos dos fármacos , Cucumis sativus/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Reguladores de Crescimento de Planta/farmacologia , Esteroides Heterocíclicos/farmacologia , Compostos de Cálcio/farmacologia , Clorofila/metabolismo , Cloroplastos/ultraestrutura , Cucumis sativus/fisiologia , Cucumis sativus/ultraestrutura , Nitratos/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Folhas de Planta/ultraestrutura , Plântula/efeitos dos fármacos , Plântula/fisiologia , Plântula/ultraestrutura , Estresse Fisiológico/efeitos dos fármacos
14.
Physiol Plant ; 146(3): 285-96, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22452600

RESUMO

With the objective to clarify the physiological significance of polyamines (PAs) in the photosynthetic apparatus, the present study investigated the effects of salt stress with and without foliar application of putrescine (Put) on the structure and function of the photosynthetic apparatus in cucumber. Salt stress at 75 mM NaCl for 7 days resulted in a severe reduction of photosynthesis. The fast chlorophyll afluorescence transient analysis showed that salt stress inhibited the maximum quantum yield of PSII photochemistry (F(v)/F(m)), mainly due to damage at the receptor side of PSII. In addition, salt stress decreased the density of active reaction centers and the structure performance. The microscopic analysis revealed that salt stress-induced destruction of the chloroplast envelope and increased the number of plastoglobuli along with aberrations in thylakoid membranes. Besides, salt stress caused a decrease in the content of endogenous PAs, conjugated and bound forms of spermidine and spermine in particular, in thylakoid membranes. However, applications of 8 mM Put alleviated the salt stress-mediated decrease in net photosynthetic rates (Pn) and actual efficiency of PSII(Φ(PSII)). Put increased PAs in thylakoid membranes and overcame the damaging effects of salt stress on the structure and function of the photosynthetic apparatus in salt-stressed plant leaves. Put application to control plants neither increased PAs in thylakoid membranes nor affected photosynthesis. These results indicate that PAs in chloroplasts play crucial roles in protecting the thylakoid membranes against the deleterious influences of salt stress. In addition, the present results point to the probability that the salt-induced dysfunction of photosynthesis is largely attributable to the loss of PAs in the photosynthetic apparatus.


Assuntos
Cucumis sativus/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Complexo de Proteína do Fotossistema II/efeitos dos fármacos , Poliaminas/metabolismo , Putrescina/farmacologia , Cloreto de Sódio/farmacologia , Clorofila/metabolismo , Cloroplastos/efeitos dos fármacos , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Cucumis sativus/fisiologia , Cucumis sativus/ultraestrutura , Fluorescência , Células do Mesofilo/efeitos dos fármacos , Células do Mesofilo/metabolismo , Células do Mesofilo/ultraestrutura , Fotoquímica , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Folhas de Planta/ultraestrutura , Plântula/efeitos dos fármacos , Plântula/fisiologia , Plântula/ultraestrutura , Espermidina/metabolismo , Espermina/metabolismo , Estresse Fisiológico , Tilacoides/efeitos dos fármacos , Tilacoides/metabolismo , Tilacoides/ultraestrutura
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