Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 96
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Plant J ; 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33595908

RESUMO

Loss of chlorophyll (Chl) is a hallmark of leaf senescence, which may be regulated by Chl catabolic genes, including NON-YELLOW COLORING 1 (NYC1)-like gene (NOL). The objective of this study was to determine molecular factors and metabolic pathways underlying NOL-regulation of leaf senescence in perennial grass species. LpNOL was cloned from perennial ryegrass (Lolium perenne L) and found to be highly expressed in senescent leaves. Transient over-expression of LpNOL accelerated leaf senescence and Chl b degradation in Nicotiana benthamiana. RNA-interfering LpNOL in perennial ryegrass (NOLi) not only significantly blocked Chl degradation in senescent leaves, but delayed initiation and progression of leaf senescence. This study found in addition to functioning as a Chl b reductase, NOL could enact the functional stay-green phenotype in perennial grass species, as manifested by increased photosynthetic activities in NOLi plants. Comparative transcriptomic analysis revealed that NOL-mediated functional stay-green in perennial ryegrass was mainly through the modulation of Chl catabolism, light harvesting of photosynthesis, photorespiration, cytochrome respiration, carbohydrate catabolism, oxidative detoxification, and abscisic acid biosynthesis and signaling pathways.

2.
Plant Biol (Stuttg) ; 2020 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-33188719

RESUMO

Phosphatidic acid (PA) and hydrogen peroxide (H2 O2 ) play roles in regulating plant responses to abiotic stress. The objective of this study was to determine effects of H2 O2 or PA individually and interactively a with a H2 O2 scavenging molecule, N,N'-dimethylthoiurea (DMTU), on plant tolerance to heat stress in tall fescue (Festuca arundinacea). Plants were treated with PA (25 µM), H2 O2 (5 mM) and PA (25 µM) + DMTU (5 mM) by foliar application and then exposed to heat stress (38/33 °C) and optimal temperature (23/18 °C, day/night) for 28 d. Foliar application of PA and H2 O2 alone resulted in increases in leaf fresh weight, chlorophyll content, photochemical efficiency and cellular membrane stability in plants exposed to heat stress, whereas addition of DMTU suppressed the positive effects of PA. The expression levels of genes encoding PA synthesizing enzymes, FaPLDδ, were significantly up-regulated by H2 O2 . PA- or H2 O2 -enhanced heat tolerance was associated with the activation of stress signaling components (FaCDPK3, FaMPK6, FaMPK3), transcription factor (FaMBF1 and FaHsfA2c), and heat shock proteins (FaHSP18, FaHSP70 and FaHSP90). PA and H2 O2 may work coordinately for further improvement in heat tolerance, involving up-regulation of transcriptional factors in stress signaling cascades and heat protection systems.

3.
BMC Plant Biol ; 20(1): 520, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-33198630

RESUMO

BACKGROUND: Identification of genetic diversity in heat tolerance and associated traits is of great importance for improving heat tolerance in cool-season grass species. The objectives of this study were to determine genetic variations in heat tolerance associated with phenotypic and physiological traits and to identify molecular markers associated with heat tolerance in a diverse collection of perennial ryegrass (Lolium perenne L.). RESULTS: Plants of 98 accessions were subjected to heat stress (35/30 °C, day/night) or optimal growth temperature (25/20 °C) for 24 d in growth chambers. Overall heat tolerance of those accessions was ranked by principal component analysis (PCA) based on eight phenotypic and physiological traits. Among these traits, electrolyte leakage (EL), chlorophyll content (Chl), relative water content (RWC) had high correlation coefficients (- 0.858, 0.769, and 0.764, respectively) with the PCA ranking of heat tolerance. We also found expression levels of four Chl catabolic genes (CCGs), including LpNYC1, LpNOL, LpSGR, and LpPPH, were significant higher in heat sensitive ryegrass accessions then heat tolerant ones under heat stress. Furthermore, 66 pairs of simple sequence repeat (SSR) markers were used to perform association analysis based on the PCA result. The population structure of ryegrass can be grouped into three clusters, and accessions in cluster C were relatively more heat tolerant than those in cluster A and B. SSR markers significantly associated with above-mentioned traits were identified (R2 > 0.05, p < 0.01)., including two pairs of markers located on chromosome 4 in association with Chl content and another four pairs of markers in association with EL. CONCLUSION: The result not only identified useful physiological parameters, including EL, Chl content, and RWC, and their associated SSR markers for heat-tolerance breeding of perennial ryegrass, but also highlighted the involvement of Chl catabolism in ryegrass heat tolerance. Such knowledge is of significance for heat-tolerance breeding and heat tolerance mechanisms in perennial ryegrass as well as in other cool-season grass species.

4.
Plant Cell Physiol ; 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32931553

RESUMO

Choline, as a precursor of glycine betaine (GB) and phospholipids, is known to play roles in plant tolerance to salt stress, but the downstream metabolic pathways regulated by choline conferring salt tolerance are still unclear for non-GB accumulating species. The objectives were to examine how choline affect salt tolerance in a non-GB accumulating grass species and to determine major metabolic pathways of choline regulating salt tolerance involving GB or lipid metabolism. Kentucky bluegrass (Poa pratensis) plants were subjected to salt stress (100 mM NaCl) with or without foliar application of choline chloride (1 mM) in a growth chamber. Choline or GB alone and the combined application increased leaf photochemical efficiency, relative water content, and osmotic adjustment, and reduced leaf electrolyte leakage. Choline application had no effects on endogenous GB content and GB-synthesis genes did not show responses to choline under non-stress and salt stress conditions. GB was not detected in Kentucky bluegrass leaves. Lipidomic analysis revealed an increase in content of monogalactosyl diacylglycerol, phosphatidylcholine and phosphatidylethanolamine, and a decrease of phosphatidic acid content by choline application in plants exposed to salt stress. Choline-mediated lipid reprogramming could function as a dominant salt tolerance mechanism in non-GB accumulating grass species.

5.
Plant Physiol Biochem ; 155: 570-578, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32846392

RESUMO

Aluminum (Al) can be detrimental to plant growth in areas with Al contamination. The objective of this study was to determine whether salicylic acid (SA) can improve plant tolerance to Al stress by mitigating Al toxicity for chloroplasts and photosynthetic systems in alfalfa (Medicago sativa L.). Plants were treated with Al (100 µM) for 3 d in a hydroponic system. The content of Al increased in leaves treated with Al, resulting in damage and deformation of chloroplasts. In Al-damaged leaves, chloroplast envelopes and starch granules disappeared; the lamellae and stroma lamella were loosely arranged and indistinguishable, and the number of grana was reduced; a large number of small plastoglobules appeared. Foliar spraying of 15 µM SA reduced Al content in roots and leaves and alleviated Al damages in chloroplasts. With 15 µM SA treatments, the chloroplast shape returned to a flat ellipsoid, thylakoids were arranged closely and regularly, chloroplasts had intact starch granules, and small plastoglobules disappeared. SA-treated plants had significantly higher aboveground biomass than the untreated control exposed to Al stress. Photosynthetic index and gene expression analyses demonstrated that SA could alleviate adverse effects of Al toxicity by increasing light capture efficiency, promoting electron transport in the photosynthetic electron transport chain and thylakoid lumen deacidification, and promoting synthesis of aenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). SA played protective roles in maintaining integrity and functions of photosystems in photosynthesis for plant tolerance to Al stress.

6.
Ann Bot ; 126(3): 481-497, 2020 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-32445476

RESUMO

BACKGROUND AND AIMS: Rhizomes are key organs for the establishment of perennial grass stands and adaptation to environmental stress. However, mechanisms regulating rhizome initiation and elongation under drought stress and during post-drought recovery remain unclear. The objective of this study is to investigate molecular factors and metabolic processes involved in drought effects and post-drought recovery in rhizome growth in perennial grass species by comparative transcriptomic and proteomic profiling. METHODS: Tall fescue (Festuca arundinacea) (B-type rhizome genotype, 'BR') plants were exposed to drought stress and re-watering in growth chambers. The number and length of rhizomes were measured following drought stress and re-watering. Hormone and sugar contents were analysed, and transcriptomic and proteomic analyses were performed to identify metabolic factors, genes and proteins associated with rhizome development. KEY RESULTS: Rhizome initiation and elongation were inhibited by drought stress, and were associated with increases in the contents of abscisic acid (ABA) and soluble sugars, but declines in the contents of indoleacetic acid (IAA), zeatin riboside (ZR) and gibberellin (GA4). Genes involved in multiple metabolic processes and stress defence systems related to rhizome initiation exhibited different responses to drought stress, including ABA signalling, energy metabolism and stress protection. Drought-inhibition of rhizome elongation could be mainly associated with the alteration of GA4 and antioxidants contents, energy metabolism and stress response proteins. Upon re-watering, new rhizomes were regenerated from rhizome nodes previously exposed to drought stress, which was accompanied by the decline in ABA content and increases in IAA, ZR and GA4, as well as genes and proteins for auxin, lipids, lignin and nitrogen metabolism. CONCLUSIONS: Drought-inhibition of rhizome initiation and elongation in tall fescue was mainly associated with adjustments in hormone metabolism, carbohydrate metabolism and stress-defence systems. Rhizome regeneration in response to re-watering involved reactivation of hormone and lipid metabolism, secondary cell-wall development, and nitrogen remobilization and cycling.


Assuntos
Secas , Poaceae/genética , Ácido Abscísico , Regulação da Expressão Gênica de Plantas , Proteômica , Rizoma
7.
Plant Cell Environ ; 43(1): 159-173, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31600831

RESUMO

Choline may affect salt tolerance by regulating lipid and glycine betaine (GB) metabolism. This study was conducted to determine whether alteration of lipid profiles and GB metabolism may contribute to choline regulation and genotypic variations in salt tolerance in a halophytic grass, seashore paspalum (Paspalum vaginatum). Plants of Adalayd and Sea Isle 2000 were subjected to salt stress (200-mM NaCl) with or without foliar application of choline chloride (1 mM). Genotypic variations in salt tolerance and promotive effects of choline application on salt tolerance were associated with both the up-regulation of lipid metabolism and GB synthesis. The genotypic variations in salt tolerance associated with lipid metabolism were reflected by the differential accumulation of phosphatidylcholine and phosphatidylethanolamine between Adalayd and Sea Isle 2000. Choline-induced salt tolerance was associated with of the increase in digalactosyl diacylglycerol (DGDG) content including DGDG (36:4 and 36:6) in both cultivars of seashore paspalum and enhanced synthesis of phosphatidylinositol (34:2, 36:5, and 36:2) and phosphatidic acid (34:2, 34:1, and 36:5), as well as increases in the ratio of digalactosyl diacylglycerol: monogalactosyl diacylglycerol (DGDG:MGDG) in salt-tolerant Sea Isle 2000. Choline regulation of salt tolerance may be due to the alteration in lipid metabolism in this halophytic grass species.


Assuntos
Betaína/metabolismo , Colina/farmacologia , Metabolismo dos Lipídeos/fisiologia , Paspalum/metabolismo , Tolerância ao Sal/efeitos dos fármacos , Plantas Tolerantes a Sal/metabolismo , Regulação para Cima/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Metabolismo dos Lipídeos/genética , Paspalum/genética , Desenvolvimento Vegetal , Folhas de Planta/genética , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Estresse Salino , Tolerância ao Sal/genética , Espectrometria de Massas em Tandem
8.
Biotechnol Biofuels ; 12: 224, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31548866

RESUMO

Background: Switchgrass (Panicum virgatum) is a warm-season perennial grass. Improving its cold tolerance is important for its sustainable production in cooler regions. Through genome-wide bioinformatic analysis of switchgrass Zinc finger-CCCH genes (PvC3Hs), we found that several PvC3Hs, including PvC3H72, might play regulatory roles in plant cold tolerance. The objectives of this study were to characterize PvC3H72 using reverse genetics approach and to understand its functional role in cold signal transduction and cold tolerance in switchgrass. Results: PvC3H72 is an intronless gene encoding a transcriptional activation factor. The expression of PvC3H72 was rapidly and highly induced by cold stress. Transgenic switchgrass with over-expressed PvC3H72 driven under maize ubiquitin promoter showed significantly improved chilling tolerance at 4 °C as demonstrated by less electrolyte leakage and higher relative water content than wild-type (WT) plants, as well as significantly higher survival rate after freezing treatment at - 5 °C. Improved cold tolerance of PvC3H72 transgenic lines was associated with significantly up-regulated expression of ICE1-CBF-COR regulon and ABA-responsive genes during cold treatment. Conclusions: PvC3H72 was the first characterized switchgrass cold-tolerance gene and also the only Znf-CCCH family gene known as a transcription factor in plant cold tolerance. PvC3H72 was an added signaling component in plant cold tolerance associated with regulation of ICE1-CBF-COR regulon and ABA-responsive genes. Knowledge gained in this study not only added another acting component into plant cold-tolerance mechanism, but also be of high value for genetic improvement of cold tolerance in switchgrass as well as other warm-season grasses.

9.
Plant Sci ; 287: 110168, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31481214

RESUMO

Tiller production in grass species is controlled by both axillary bud initiation and bud outgrowth, which may be regulated by plant hormones. However, how gibberellic acid (GA) affects tillering in perennial grass species is still unclear. This study aims to elucidate the roles and the underlying mechanisms of GA in regulating tiller development. Tall fescue seedlings were treated with different concentrations of GA3 by foliar application, dose-dependent inhibitory effects of GA on tiller production were observed. GA3 (25 µM) slowed down the transition from axillary buds to tillers by specifically inhibiting the outgrowth of axillary buds. GA-inhibition of tillering were not related to endogenous content for auxin or strigolactone, but was mainly due to the antagonistic interaction with cytokinins (CK), as shown by the decreased CK content and up-regulation expression of CK degradation genes in GA3-treated plants. Furthermore, GA could act through regulating the expression of FaTB1 specifically expressed in axillary buds to repress bud outgrowth. These results provide insights for the regulatory mechanisms of GA for tiller bud outgrowth through crosstalks with CK and signaling of FaTB1 expression.


Assuntos
Citocininas/metabolismo , Festuca/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas/fisiologia , Reguladores de Crescimento de Planta/fisiologia , Brotos de Planta/crescimento & desenvolvimento , Citocininas/fisiologia , Festuca/genética , Festuca/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas/genética , Giberelinas , Brotos de Planta/metabolismo , Receptor Cross-Talk
10.
J Proteome Res ; 18(6): 2446-2457, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-31081640

RESUMO

Elevated atmospheric CO2 and nitrogen are major environmental factors affecting shoot growth. The objectives of this study are to determine the interactive effects of elevated CO2 and nitrogen on leaf growth in tall fescue ( Festuca arundinacea) and to identify major proteins and associated metabolic pathways underlying CO2-regulation of leaf growth under insufficient and sufficient nitrate conditions using proteomic analysis. Plants of tall fescue treated with low nitrate level (0.25 mM, LN), moderate nitrate level (4 mM, MN) and high nitrate level (32 mM, HN) were exposed to ambient (400 µmol mol-1) and elevated (800 µmol mol-1) CO2 concentrations in environment-controlled growth chambers. Increased atmospheric CO2 concentration increased leaf length and shoot biomass, which corresponded to increased content of indo-acetic acid, gibberellic acid, cytokinins and reduced content of abscisic acid under sufficient nitrate conditions (MN and HN conditions). Low nitrate supply limited shoot growth and hormonal responses to elevated CO2. Proteomic analysis of plants exposed to elevated CO2 under LN and MN conditions demonstrated the increases in the abundance of many proteins due to elevated CO2 under MN condition involved with cell cycle and proliferation, transcription and translation, photosynthesis (ribosomal and chlorophyll a/b-binding proteins), amino acids synthesis, sucrose and starch metabolism, as well as ABA signaling pathways (ABA-induced proteins). Our results revealed major proteins and associated metabolic pathways associated with the interactive effects of elevated CO2 and nitrate regulating leaf growth in a perennial grass species.


Assuntos
Dióxido de Carbono/metabolismo , Redes e Vias Metabólicas/genética , Nitrogênio/metabolismo , Proteômica , Metabolismo dos Carboidratos/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Citocininas/metabolismo , Giberelinas/metabolismo , Nitratos/farmacologia , Nitrogênio/farmacologia , Fotossíntese/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/genética , Plantas Daninhas/crescimento & desenvolvimento
11.
Physiol Plant ; 167(4): 488-501, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30977137

RESUMO

Abscisic acid (ABA) may play roles in mediating cross stress tolerance in plants. The objectives of this study were to investigate the priming effects of drought and ABA on heat tolerance and to determine how ABA may be involved in enhanced heat tolerance by drought. Focusing on the transcriptional level, two independent experiments were conducted, using a perennial grass species, tall fescue (Festuca arundinacea) and Arabidopsis. In experiment 1, tall fescue plants were exposed to mild drought by withholding irrigation for 8 days (drought priming) and foliar sprayed with ABA or an ABA-synthesis inhibitor (fluridone). After that they were subsequently subjected to heat stress (38/33°C day/night) for 25 days in growth chambers. In experiment 2, Arabidopsis Columbia ecotype (wild-type) and ABA-deficient mutant (aba3-1, CS157) were pre-treated with drought priming and then exposed to heat stress (45/40°C) for 3 days. The physiological analysis demonstrated that both drought priming and foliar application of ABA-enhanced heat tolerance in tall fescue, while drought priming had no significant effects on heat tolerance in ABA-deficient Arabidopsis plants. Application of fluridone to tall fescue and ABA-deficient mutants of Arabidopsis exhibited diminished or attenuated positive effects of drought priming on heat tolerance. ABA mediation of acquired heat tolerance by drought priming was associated with the upregulation of CDPK3, MPK3, DREB2A, AREB3, MYB2, MYC4, HsfA2, HSP18, and HSP70. Our study revealed the roles of ABA in drought priming-enhanced heat tolerance, which may involve transcriptional regulation for stress signaling, ABA responses and heat protection.


Assuntos
Ácido Abscísico/metabolismo , Arabidopsis/fisiologia , Secas , Festuca/fisiologia , Estresse Fisiológico , Termotolerância , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Temperatura Alta
12.
Int J Mol Sci ; 20(8)2019 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-31013928

RESUMO

Strigolactones (SLs) have recently been shown to play roles in modulating plant architecture and improving plant tolerance to multiple stresses, but the underlying mechanisms for SLs regulating leaf elongation and the influence by air temperature are still unknown. This study aimed to investigate the effects of SLs on leaf elongation in tall fescue (Festuca arundinacea, cv. 'Kentucky-31') under different temperature regimes, and to determine the interactions of SLs and auxin in the regulation of leaf growth. Tall fescue plants were treated with GR24 (synthetic analog of SLs), naphthaleneacetic acid (NAA, synthetic analog), or N-1-naphthylphthalamic acid (NPA, auxin transport inhibitor) (individually and combined) under normal temperature (22/18 °C) and high-temperature conditions (35/30 °C) in controlled-environment growth chambers. Exogenous application of GR24 stimulated leaf elongation and mitigated the heat inhibition of leaf growth in tall fescue. GR24-induced leaf elongation was associated with an increase in cell numbers, upregulated expression of cell-cycle-related genes, and downregulated expression of auxin transport-related genes in elongating leaves. The results suggest that SLs enhance leaf elongation by stimulating cell division and interference with auxin transport in tall fescue.


Assuntos
Festuca/efeitos dos fármacos , Festuca/fisiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes cdc , Lactonas/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/fisiologia , Transporte Biológico , Resposta ao Choque Térmico/efeitos dos fármacos , Resposta ao Choque Térmico/genética , Ácidos Indolacéticos/metabolismo , Lactonas/química , Temperatura
13.
Nanoscale ; 11(11): 4959-4969, 2019 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-30839016

RESUMO

In this study, we systematically investigate the decay characteristics of upconversion luminescence (UCL) under anti-Stokes excitation through numerical simulations based on rate-equation models. We find that a UCL decay profile generally involves contributions from the sensitizer's excited-state lifetime, energy transfer and cross-relaxation processes. It should thus be regarded as the overall temporal response of the whole upconversion system to the excitation function rather than the intrinsic lifetime of the luminescence emitting state. Only under certain conditions, such as when the effective lifetime of the sensitizer's excited state is significantly shorter than that of the UCL emitting state and of the absence of cross-relaxation processes involving the emitting energy level, the UCL decay time approaches the intrinsic lifetime of the emitting state. Subsequently, Stokes excitation is generally preferred in order to accurately quantify the intrinsic lifetime of the emitting state. However, possible cross-relaxation between doped ions at high doping levels can complicate the decay characteristics of the luminescence and even make the Stokes-excitation approach fail. A strong cross-relaxation process can also account for the power dependence of the decay characteristics of UCL.

14.
Nanoscale ; 11(4): 1563-1569, 2019 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-30644963

RESUMO

Multi-photon upconversion super-resolution microscopy is a recently proposed imaging modality, based on lanthanide-doped nanocrystals, which can emit visible emission upon low-intensity near-infrared excitation. This imaging modality exhibits many advantages, including increased imaging depth, high signal-to-noise ratio, low phototoxicity, and high photostability. However, two factors seriously restrict its scanning speed, sometimes even to an intolerable degree; the long lanthanide emission lifetime and the low brightness. For proper imaging, pixel dwell times of several milliseconds are often required. In this work, a facile strategy is proposed to overcome these two obstacles. By adopting a high sensitizer (Yb3+) doping strategy for upconversion nanocrystals, their emission intensity is greatly increased and their emission transients are significantly accelerated, without losing the emission depletion efficiency induced by the depletion laser. This enables the implementation of a very fast upconversion stimulated emission depletion super-resolution microscopy with a scanning speed of 10 µs per pixel. This work opens the possibility for upconversion super-resolution microscopy to capture vital biological activities in real time.

15.
Plant Cell Physiol ; 60(1): 202-212, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30329104

RESUMO

Chl breakdown is a hallmark of leaf senescence. Protein degradation is tightly associated with accelerated Chl catabolism during leaf senescence. Therefore, blocking or reducing Chl breakdown and thereby improving Chl and leaf protein contents is desirable for agronomic improvement in perennial forage grasses. Perennial ryegrass (Lolium perenne L.) is one principle cool-season forage grass in temperate areas throughout the world. In this study, the perennial ryegrass STAY-GREEN gene (LpSGR) was cloned and characterized. LpSGR was highly expressed in developmentally or dark-induced senescent leaves. LpSGR was subcellularly localized in chloroplast and interacted with the other Chl catabolic enzymes. RNA interference (RNAi) of LpSGR in perennial ryegrass blocked the degradation of Chl, resulting in increased Chl content and photochemical efficiency in senescent leaves. The RNAi transgenic plants had significantly improved forage quality, with up to 46.1% increased protein content in the harvested biomass. Transcriptome comparison revealed that suppression of LpSGR led to multiple alterations in metabolic pathways in locations inside the chloroplast. Most transcription factors of senescence-associated hormonal signaling pathways (e.g. ABA, ethylene and jasmonic acid) had decreased expression levels in the RNAi plants. These results provided a foundation for the further study on the regulatory mechanism of LpSGR in perennial ryegrass for the purpose of forage improvement with delayed leaf senescence and higher forage quality.


Assuntos
Técnicas de Silenciamento de Genes , Genes de Plantas , Lolium/genética , Folhas de Planta/crescimento & desenvolvimento , Transcriptoma/genética , Colesterol/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Fenótipo , Filogenia , Plantas Geneticamente Modificadas
16.
Plant Cell Environ ; 42(3): 947-958, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-29989186

RESUMO

Stress priming by exposing plants to a mild or moderate drought could enhance plant tolerance to subsequent heat stress. Lipids play vital roles in stress adaptation, but how lipidomic profiles change, affecting the cross-stress tolerance, is largely unknown. The objectives of this study were to perform lipidomics, to analyse the content, composition, and saturation levels of lipids in leaves of tall fescue (Festuca arundinacea) following drought priming and subsequent heat stress, and to identify major lipids and molecular species associated with priming-enhanced heat tolerance. Plants were initially exposed to drought for 8 days by withholding irrigation and subsequently subjected to 25 days of heat stress (38/33°C day/night) in growth chambers. Drought-primed plants maintained significantly higher leaf relative water content, chlorophyll content, photochemical efficiency, and lower electrolyte leakage than nonprimed plants under heat stress. Drought priming enhanced the accumulation of phospholipids and glycolipids involved in membrane stabilization and stress signalling (phosphatidic acid, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, and digalactosyl diacylglycerol) during subsequent exposure to heat stress. The reprogramming of lipid metabolism for membrane stabilization and signalling in response to drought priming and subsequent exposure to heat stress could contribute to drought priming-enhanced heat tolerance in cool-season grass species.


Assuntos
Festuca/fisiologia , Lipídeos/fisiologia , Adaptação Fisiológica/fisiologia , Desidratação , Festuca/metabolismo , Resposta ao Choque Térmico , Metabolismo dos Lipídeos/fisiologia , Lipidômica
17.
BMC Plant Biol ; 18(1): 299, 2018 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-30477420

RESUMO

BACKGROUND: Dehydrins play positive roles in regulating plant abiotic stress responses. The objective of this study was to characterize two dehydrin genes, CdDHN4-L and CdDHN4-S, generated by alternative splicing of CdDHN4 in bermudagrass. RESULTS: Overexpression of CdDHN4-L with φ-segment and CdDHN4-S lacking of φ-segment in Arabidopsis significantly increased tolerance against abiotic stresses. The growth phenotype of Arabidopsis exposed to NaCl at 100 mM was better in plants overexpressing CdDHN4-L than those overexpressing CdDHN4-S, as well as better in E.coli cells overexpressing CdDHN4-L than those overexpressing CdDHN4-S in 300 and 400 mM NaCl, and under extreme temperature conditions at - 20 °C and 50 °C. The CdDHN4-L had higher disordered characterization on structures than CdDHN4-S at temperatures from 10 to 90 °C. The recovery activities of lactic dehydrogenase (LDH) and alcohol dehydrogenase (ADH) in presence of CdDHN4-L and CdDHN4-S were higher than that of LDH and ADH alone under freeze-thaw damage and heat. Protein-binding and bimolecular fluorescence complementation showed that both proteins could bind to proteins with positive isoelectric point via electrostatic forces. CONCLUSIONS: These results indicate that CdDHN4-L has higher protective ability against abiotic stresses due to its higher flexible unfolded structure and thermostability in comparison with CdDHN4-S. These provided direct evidence of the function of the φ-segment in dehydrins for protecting plants against abiotic stress and to show the electrostatic interaction between dehydrins and client proteins.


Assuntos
Cynodon/fisiologia , Proteínas de Plantas/fisiologia , Estresse Fisiológico , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Clonagem Molecular , Cynodon/genética , Proteínas de Plantas/genética , Ligação Proteica , Estrutura Secundária de Proteína , Temperatura
19.
Nanoscale ; 10(45): 21025-21030, 2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30427028

RESUMO

We experimentally realized one-scan fluorescence emission difference nanoscopy (FED) by simultaneously imaging two different color emissions of NaYF4:Er3+@NaYF4@NaYF4:Yb3+/Tm3+ upconversion nanoparticles. Under the irradiation of two synchronized laser beams, a solid 940 nm beam and a hollow 808 nm beam, green emission of Er3+ and blue emission of Tm3+ can be orthogonally generated and collected. After simple subtraction, a resulting super-resolution image featuring 54 nm resolution was obtained. This strategy of excitation orthogonality would greatly improve the imaging speed and the applicability of FED nanoscopy.

20.
Sci Rep ; 8(1): 15181, 2018 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-30315246

RESUMO

Heat and drought stress are primary abiotic stresses confining growth of cool-season grass species during summer. The objective of this study was to identify common molecular factors and metabolic pathways associated with heat and drought responses in creeping bentgrass (Agrostis stolonifera) by comparative analysis of transcriptomic profiles between plants exposed to heat and drought stress. Plants were exposed to heat stress (35/30 °C day/night temperature) or drought stress by withholding irrigation for 21 d in growth chambers. Transcriptomic profiling by RNA-seq in A. stolonifera (cv. 'Penncross') found 670 commonly up-regulated and 812 commonly down-regulated genes by heat and drought stress. Transcriptional up-regulations of differentially expressed genes (DEGs) due to heat and drought stress include genes that were highly enriched in oxylipin biosynthetic process and proline biosynthetic process. Transcriptional down-regulations of genes under heat and drought stress were highly enriched and involved in thiamine metabolic process and calcium sensing receptor. These commonly-regulated genes by heat and drought stress identified in A. stolonifera suggested that drought and heat responses shared such common molecular factors and pathways, which could be potential candidate genes for genetic modification of improving plant tolerance to the combined heat and drought stress.


Assuntos
Agrostis/genética , Agrostis/fisiologia , Secas , Perfilação da Expressão Gênica , Temperatura Alta , Estresse Fisiológico/genética , Regulação para Baixo/genética , Eletrólitos/metabolismo , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Folhas de Planta/fisiologia , Reprodutibilidade dos Testes , Regulação para Cima/genética , Água/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...