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1.
Planta ; 254(3): 50, 2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34386845

RESUMO

MAIN CONCLUSION: Overexpression of the leaf color (Lc) gene in Ma bamboo substantially increased the accumulation level of anthocyanin, and improved plant tolerance to cold and drought stresses, probably due to the increased antioxidant capacity. Most bamboos, including Ma bamboo (Dendrocalamus latiflorus Munro), are naturally evergreen and sensitive to cold and drought stresses, while it's nearly impossible to make improvements through conventual breeding due to their long and irregular flowering habit. Moreover, few studies have reported bamboo germplasm innovation through genetic engineering as bamboo genetic transformation remains difficult. In this study, we have upregulated anthocyanin biosynthesis in Ma bamboo, to generate non-green Ma bamboo with increased abiotic stress tolerance. By overexpressing the maize Lc gene, a bHLH transcription activator involved in the anthocyanin biosynthesis in Ma bamboo, we generated purple bamboos with increased anthocyanin levels including cyanidin-3-O-rutinoside, peonidin 3-O-rutinoside, and an unknown cyanidin pentaglycoside derivative. The expression levels of 9 anthocyanin biosynthesis genes were up-regulated. Overexpression of the Lc gene improved the plant tolerance to cold and drought stress, probably due to increased antioxidant capacity. The levels of the cold- and drought-related phytohormone jasmonic acid in the transgenic plants were also enhanced, which may also contribute to the plant stress-tolerant phenotypes. High anthocyanin accumulation level did not affect plant growth. Transcriptomic analysis showed higher expressions of genes involved in the flavonoid pathway in Lc transgenic bamboos compared with those in wild-type ones. The anthocyanin-rich bamboos generated here provide an example of ornamental and multiple agronomic trait improvements by genetic engineering in this important grass species.


Assuntos
Secas , Regulação da Expressão Gênica de Plantas , Antocianinas , Resposta ao Choque Frio , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/metabolismo
2.
Cells ; 10(7)2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-34359847

RESUMO

Auxin plays a dual role in growth regulation and, depending on the tissue and concentration of the hormone, it can either promote or inhibit division and expansion processes in plants. Recent studies have revealed that, beyond transcriptional reprogramming, alternative auxin-controlled mechanisms regulate root growth. Here, we explored the impact of different concentrations of the synthetic auxin NAA that establish growth-promoting and -repressing conditions on the root tip proteome and phosphoproteome, generating a unique resource. From the phosphoproteome data, we pinpointed (novel) growth regulators, such as the RALF34-THE1 module. Our results, together with previously published studies, suggest that auxin, H+-ATPases, cell wall modifications and cell wall sensing receptor-like kinases are tightly embedded in a pathway regulating cell elongation. Furthermore, our study assigned a novel role to MKK2 as a regulator of primary root growth and a (potential) regulator of auxin biosynthesis and signalling, and suggests the importance of the MKK2 Thr31 phosphorylation site for growth regulation in the Arabidopsis root tip.

3.
EMBO Rep ; 22(10): e52457, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34402578

RESUMO

Cytokinins are phytohormones that regulate plant development, growth, and responses to stress. In particular, cytokinin has been reported to negatively regulate plant adaptation to high salinity; however, the molecular mechanisms that counteract cytokinin signaling and enable salt tolerance are not fully understood. Here, we provide evidence that salt stress induces the degradation of the cytokinin signaling components Arabidopsis (Arabidopisis thaliana) response regulator 1 (ARR1), ARR10 and ARR12. Furthermore, the stress-activated mitogen-activated protein kinase 3 (MPK3) and MPK6 interact with and phosphorylate ARR1/10/12 to promote their degradation in response to salt stress. As expected, salt tolerance is decreased in the mpk3/6 double mutant, but enhanced upon ectopic MPK3/MPK6 activation in an MKK5DD line. Importantly, salt hypersensitivity phenotypes of the mpk3/6 line were significantly alleviated by mutation of ARR1/12. The above results indicate that MPK3/6 enhance salt tolerance in part via their negative regulation of ARR1/10/12 protein stability. Thus, our work reveals a new molecular mechanism underlying salt-induced stress adaptation and the inhibition of plant growth, via enhanced degradation of cytokinin signaling components.

4.
Plant J ; 2021 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-34273207

RESUMO

Aluminium (Al) stress is a major limiting factor for worldwide crop production in acid soils. In Arabidopsis thaliana, the TAA1-dependent local auxin biosynthesis in the root-apex transition zone (TZ), the major perception site for Al toxicity, is crucial for the Al-induced root-growth inhibition, while the mechanism underlying Al-regulated auxin accumulation in the TZ is not fully understood. In the present study, the role of auxin transport in Al-induced local auxin accumulation in the TZ and root-growth inhibition was investigated. Our results showed that PIN-FORMED (PIN) proteins such as PIN1, PIN3, PIN4 and PIN7 and AUX1/LAX proteins such as AUX1, LAX1 and LAX2 were all ectopically up-regulated in the root-apex TZ in response to Al stress and coordinately regulated local auxin accumulation in the TZ and root-growth inhibition. The ectopic up-regulation of PIN1 in the TZ under Al stress was regulated by both ethylene and auxin, with auxin signalling acting downstream of ethylene. Al-induced PIN1 up-regulation and auxin accumulation in the root-apex TZ was also regulated by the calossin-like protein BIG. Together, our results provide insight into how Al stress induces local auxin accumulation in the TZ and root-growth inhibition through the local regulation of auxin transport.

5.
Nat Commun ; 12(1): 1657, 2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33712581

RESUMO

Auxin is a key regulator of plant growth and development. Local auxin biosynthesis and intercellular transport generates regional gradients in the root that are instructive for processes such as specification of developmental zones that maintain root growth and tropic responses. Here we present a toolbox to study auxin-mediated root development that features: (i) the ability to control auxin synthesis with high spatio-temporal resolution and (ii) single-cell nucleus tracking and morphokinetic analysis infrastructure. Integration of these two features enables cutting-edge analysis of root development at single-cell resolution based on morphokinetic parameters under normal growth conditions and during cell-type-specific induction of auxin biosynthesis. We show directional auxin flow in the root and refine the contributions of key players in this process. In addition, we determine the quantitative kinetics of Arabidopsis root meristem skewing, which depends on local auxin gradients but does not require PIN2 and AUX1 auxin transporter activities. Beyond the mechanistic insights into root development, the tools developed here will enable biologists to study kinetics and morphology of various critical processes at the single cell-level in whole organisms.


Assuntos
Arabidopsis/metabolismo , Ácidos Indolacéticos/metabolismo , Desenvolvimento Vegetal , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cinética , Meristema/metabolismo , Oxigenases/metabolismo , Raízes de Plantas/citologia
6.
J Integr Plant Biol ; 63(6): 1147-1160, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33710720

RESUMO

Sensitive to proton rhizotoxicity 1 (STOP1) functions as a crucial regulator of root growth during aluminum (Al) stress. However, how this transcription factor is regulated by Al stress to affect downstream genes expression is not well understood. To explore the underlying mechanisms of the function and regulation of STOP1, we employed a yeast two hybrid screen to identify STOP1-interacting proteins. The SUMO E3 ligase SIZ1, was found to interact with STOP1 and mainly facilitate its SUMO modification at K40 and K212 residues. Simultaneous introduction of K40R and K212R substitutions in STOP1 enhances its transactivation activity to upregulate the expression of aluminum-activated malate transporter 1 (ALMT1) via increasing the association with mediator 16 (MED16) transcriptional co-activator. Loss of function of SIZ1 causes highly increased expression of ALMT1, thus enhancing Al-induced malate exudation and Al tolerance. Also, we found that the protein level of SIZ1 is reduced in response to Al stress. Genetic evidence demonstrates that STOP1/ALMT1 is epistatic to SIZ1 in regulating root growth response to Al stress. This study suggests a mechanism about how the SIZ1-STOP1-ALMT1 signaling module is involved in root growth response to Al stress.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição/metabolismo , Alumínio/toxicidade , Arabidopsis/genética , Arabidopsis/toxicidade , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/genética
7.
Plant J ; 106(4): 928-941, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33609310

RESUMO

The plant hormone auxin plays a critical role in root growth and development; however, the contributions or specific roles of cell-type auxin signals in root growth and development are not well understood. Here, we mapped tissue and cell types that are important for auxin-mediated root growth and development by manipulating the local response and synthesis of auxin. Repressing auxin signaling in the epidermis, cortex, endodermis, pericycle or stele strongly inhibited root growth, with the largest effect observed in the endodermis. Enhancing auxin signaling in the epidermis, cortex, endodermis, pericycle or stele also caused reduced root growth, albeit to a lesser extent. Moreover, we established that root growth was inhibited by enhancement of auxin synthesis in specific cell types of the epidermis, cortex and endodermis, whereas increased auxin synthesis in the pericycle and stele had only minor effects on root growth. Our study thus establishes an association between cellular identity and cell type-specific auxin signaling that guides root growth and development.

8.
Plant Cell Rep ; 40(1): 59-68, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33009928

RESUMO

KEY MESSAGE: Plant growth is greatly inhibited in tightly sealed Petri dishes for lack of CO2. Bacteria which co-cultured with plant can produce CO2 to promote plant growth in sealed systems. Bacteria produce a wide variety of volatiles, some of which can support and others can damage plant growth. It is a controversial issue whether CO2 or other bacterial volatile compounds promote plant growth in sealed systems. CO2 is critical for photosynthesis. Here, we show that CO2 is a key constituent of the plant growth-promoting volatiles generated by bacteria in a sealed system. We revealed that the growth of Arabidopsis seedlings in an airtight container was retarded due to insufficient supply of the CO2. When either CO2 was introduced into the container, or the seedlings were co-cultured along with certain bacterial species, the plants' growth was restored. CONCLUSION: The benefit of co-culturing was largely due to the CO2 generated by respiration of the bacteria.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Dióxido de Carbono/metabolismo , Ar , Arabidopsis/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Clorofila/metabolismo , Escherichia coli/metabolismo , Permeabilidade , Pseudomonas syringae/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Serratia marcescens/metabolismo , Compostos Orgânicos Voláteis
9.
Exp Clin Endocrinol Diabetes ; 129(2): 86-92, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31039601

RESUMO

INTRODUCTION: The HbA1c has been considered as the 'gold standard' in diabetes diagnosis and management, however, age, gender and body mass index (BMI) might have certain effects on HbA1c. We are aiming to further investigate the correlation between age and HbA1c, and whether it was affected by gender and BMI. METHODS: A cross-sectional survey including 135,893 nondiabetic individuals who took the physical examination between 2013 and 2017 was conducted. The subjects were grouped by gender, age and BMI, and the interactive and independent effects of the 3 factors on the HbA1c were detected. The median and 95% confidence interval (CI) of HbA1c levels were calculated. RESULTS: The HbA1c levels gradually increased along with age, both in female and male, and there is a positive association between BMI and the HbA1c. The difference on HbA1c in gender was associated with both age and BMI, the age-related increase in HbAlc was accentuated in the subgroup with higher BMI, and there was a marked accentuation of the positive association between BMI and HbA1c as age increased. In almost all the young and middle-aged (aged 20-59) subgroups, the 97.5th percentiles of HbA1c levels were lower than 6.5%, suggesting that the single HbA1c cutoff value is probably not applicable to the young and middle-aged population. CONCLUSIONS: We recommend that the effects of age, gender and BMI should be taken into consideration when using HbA1c for the diagnosis and management of diabetes, especially in the young and middle-aged population.

10.
J Integr Plant Biol ; 63(5): 819-822, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33215867

RESUMO

Light is the energy source for plant photosynthesis and influences plant growth and development. Through multiple photoreceptors, plant interprets light signals through various downstream phytohormones such as auxin. Recently, Chen et al. (2020) uncover a new layer of regulation in IPyA pathway of auxin biosynthesis by light. Here we highlight recent studies about how light controls plant growth through regulating auxin biosynthesis and signaling.

11.
Mol Plant ; 14(2): 285-297, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33221411

RESUMO

Auxin plays a critical role in lateral root (LR) formation. The signaling module composed of auxin-response factors (ARFs) and lateral organ boundaries domain transcription factors mediates auxin signaling to control almost every stage of LR development. Here, we show that auxin-induced degradation of the APETALA2/Ethylene Responsive Factor (AP2/ERF) transcription factor ERF13, dependent on MITOGEN-ACTIVATED PROTEIN KINASE MPK14-mediated phosphorylation, plays an essential role in LR development. Overexpression of ERF13 results in restricted passage of the LR primordia through the endodermal layer, greatly reducing LR emergence, whereas the erf13 mutants showed an increase in emerged LR. ERF13 inhibits the expression of 3-ketoacyl-CoA synthase16 (KCS16), which encodes a fatty acid elongase involved in very-long-chain fatty acid (VLCFA) biosynthesis. Overexpression of KCS16 or exogenous VLCFA treatment rescues the LR emergence defects in ERF13 overexpression lines, indicating a role downstream of the auxin-MPK14-ERF13 signaling module. Collectively, our study uncovers a novel molecular mechanism by which MPK14-mediated auxin signaling modulates LR development via ERF13-regulated VLCFA biosynthesis.

12.
J Integr Plant Biol ; 63(4): 662-678, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32790237

RESUMO

Pre-mRNA (messenger RNA) splicing participates in the regulation of numerous biological processes in plants. For example, alternative splicing shapes transcriptomic responses to abiotic and biotic stress, and controls developmental programs. However, no study has revealed a role for splicing in maintaining the root stem cell niche. Here, a screen for defects in root growth in Arabidopsis thaliana identified an ethyl methane sulfonate mutant defective in pre-mRNA splicing (rdm16-4). The rdm16-4 mutant displays a short-root phenotype resulting from fewer cells in the root apical meristem. The PLETHORA1 (PLT1) and PLT2 transcription factor genes are important for root development and were alternatively spliced in rdm16-4 mutants, resulting in a disordered root stem cell niche and retarded root growth. The root cap of rdm16-4 contained reduced levels of cytokinins, which promote differentiation in the developing root. This reduction was associated with the alternative splicing of genes encoding cytokinin signaling factors, such as ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN5 and ARABIDOPSIS RESPONSE REGULATORS (ARR1, ARR2, and ARR11). Furthermore, expression of the full-length coding sequence of ARR1 or exogenous cytokinin application partially rescued the short-root phenotype of rdm16-4. This reveals that the RDM16-mediated alternative splicing of cytokinin signaling components contributes to root growth.

13.
Cell Rep ; 32(8): 108060, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32846118

RESUMO

Pathogen entry into host tissues is a critical and first step in infections. In plants, the lateral roots (LRs) are a potential entry and colonization site for pathogens. Here, using a GFP-labeled pathogenic bacterium Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), we observe that virulent Pto DC3000 invades plants through emerged LRs in Arabidopsis. Pto DC3000 strongly induced LR formation, a process that was dependent on the AUXIN RESPONSE FACTOR7 (ARF7)/ARF19-LATERAL ORGAN BOUNDARIES-DOMAIN (LBD) regulatory module. We show that salicylic acid (SA) represses LR formation, and several mutants defective in SA signaling are also involved in Pto DC3000-induced LR development. Significantly, ARF7, a well-documented positive regulator of LR development, directly represses the transcription of PR1 and PR2 to promote LR development. This study indicates that ARF7-mediated auxin signaling antagonizes with SA signaling to control bacterial infection through the regulation of LR development.


Assuntos
Infecções Bacterianas/microbiologia , Ácidos Indolacéticos/metabolismo , Raízes de Plantas/química , Arabidopsis , Transdução de Sinais
14.
Trends Plant Sci ; 25(11): 1117-1130, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32675014

RESUMO

Salt stress is one of the major environmental stresses limiting plant growth and productivity. To adapt to salt stress, plants have developed various strategies to integrate exogenous salinity stress signals with endogenous developmental cues to optimize the balance of growth and stress responses. Accumulating evidence indicates that phytohormones, besides controlling plant growth and development under normal conditions, also mediate various environmental stresses, including salt stress, and thus regulate plant growth adaptation. In this review, we mainly discuss and summarize how plant hormones mediate salinity signals to regulate plant growth adaptation. We also highlight how, in response to salt stress, plants build a defense system by orchestrating the synthesis, signaling, and metabolism of various hormones via multiple crosstalks.


Assuntos
Reguladores de Crescimento de Plantas , Estresse Salino , Desenvolvimento Vegetal , Salinidade , Estresse Fisiológico
15.
New Phytol ; 228(2): 609-621, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32521046

RESUMO

Shade avoidance syndrome (SAS) arises in densely growing plants that compete for light. In Arabidopsis thaliana, phytochrome interacting factor (PIF) proteins link the perception of shade to stem elongation via auxin production. Here, we report that PIFs inhibit the shade-induced expression of AUXIN RESPONSE FACTOR 18 (ARF18), and ARF18 represses auxin signaling. Therefore, PIF-mediated inhibition of ARF18 enhances auxin-dependent hypocotyl elongation in simulated shade. Furthermore, we show that both PIFs and ARF18 directly repress qua-quine starch (QQS), which controls the allocation of carbon and nitrogen. Shade-repressed QQS attenuates the conversion of starch to protein and thus reduced leaf area. Our results suggest that PIF-dependent gene regulation coordinates multiple SAS responses, including altered stem growth via ARF18, as well as altered leaf growth and metabolism via QQS.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fitocromo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Hipocótilo/metabolismo , Ácidos Indolacéticos , Luz , Fitocromo/metabolismo
16.
Int J Mol Sci ; 21(11)2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32517364

RESUMO

Aluminum (Al) stress is a major limiting factor for plant growth and crop production in acid soils. At present, only a few transcription factors involved in the regulation of Al resistance have been characterized. Here, we used reversed genetic approach through phenotype analysis of overexpressors and mutants to demonstrate that AtHB7 and AtHB12, two HD-Zip I transcription factors, participate in Al resistance. In response to Al stress, AtHB7 and AtHB12 displayed different dynamic expression patterns. Although both AtHB7 and AtHB12 positively regulate root growth in the absence of Al stress, our results showed that AtHB7 antagonizes with AtHB12 to control root growth in response to Al stress. The athb7/12 double mutant displayed a wild-type phenotype under Al stress. Consistently, our physiological analysis showed that AtHB7 and AtHB12 oppositely regulate the capacity of cell wall to bind Al. Yeast two hybrid assays showed that AtHB7 and AtHB12 could form homo-dimers and hetero-dimers in vitro, suggesting the interaction between AtHB7 and AtHB12 in the regulation of root growth. The conclusion was that AtHB7 and AtHB12 oppositely regulate Al resistance by affecting Al accumulation in root cell wall.


Assuntos
Alumínio/metabolismo , Proteínas de Homeodomínio/genética , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Estresse Fisiológico , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Núcleo Celular/genética , Núcleo Celular/metabolismo , Parede Celular/genética , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/química , Proteínas de Homeodomínio/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Multimerização Proteica , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
17.
Nat Nanotechnol ; 15(9): 755-760, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32572228

RESUMO

Although the fates of microplastics (0.1-5 mm in size) and nanoplastics (<100 nm) in marine environments are being increasingly well studied1,2, little is known about the behaviour of nanoplastics in terrestrial environments3-6, especially agricultural soils7. Previous studies have evaluated the consequences of nanoplastic accumulation in aquatic plants, but there is no direct evidence for the internalization of nanoplastics in terrestrial plants. Here, we show that both positively and negatively charged nanoplastics can accumulate in Arabidopsis thaliana. The aggregation promoted by the growth medium and root exudates limited the uptake of amino-modified polystyrene nanoplastics with positive surface charges. Thus, positively charged nanoplastics accumulated at relatively low levels in the root tips, but these nanoplastics induced a higher accumulation of reactive oxygen species and inhibited plant growth and seedling development more strongly than negatively charged sulfonic-acid-modified nanoplastics. By contrast, the negatively charged nanoplastics were observed frequently in the apoplast and xylem. Our findings provide direct evidence that nanoplastics can accumulate in plants, depending on their surface charge. Plant accumulation of nanoplastics can have both direct ecological effects and implications for agricultural sustainability and food safety.


Assuntos
Arabidopsis/efeitos dos fármacos , Microplásticos/química , Microplásticos/farmacocinética , Nanoestruturas/química , Arabidopsis/genética , Arabidopsis/metabolismo , Disponibilidade Biológica , Difusão Dinâmica da Luz , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Exsudatos de Plantas/química , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Poliestirenos/química , Poliestirenos/farmacocinética , Espécies Reativas de Oxigênio/metabolismo , Poluentes do Solo/química , Poluentes do Solo/farmacocinética , Distribuição Tecidual
18.
Int J Occup Med Environ Health ; 33(3): 299-310, 2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32235950

RESUMO

OBJECTIVES: The aim of this study was to determine the lag between exposure to air pollutants and changes in human eosinophil counts. MATERIAL AND METHODS: This was a retrospective study employing 246 425 physical examination records dated December 2013 - December 2016 from Chengdu, China. The authors determined the prevalence of individuals with eosinophil counts above the normal reference range each day. A distributed lag non-linear model was used to evaluate the lagged effect of each air pollutant on eosinophil counts. The lagged effects of each air pollutant were counted and presented with smoothing splines. RESULTS: The effects of air pollutants such as particulate matter (PM2.5, aerodynamic diameters <2.5 µm; PM10, aerodynamic diameters <10 µm), nitrogen dioxide (NO2) and ozone (O3) were evaluated. In women, the effects of PM2.5 (RR = 1.154, 95% CI: 1.061-1.255) and PM10 (RR = 1.309, 95% CI: 1.130-1.517) reached the maximum values on lag day 0. In men, there was no significant effect of PM2.5, but significant effects of PM10 were found for lag days 20-28. The effects of NO2 and O3 on eosinophils were not statistically significant for either gender. CONCLUSIONS: The air pollutants of PM10 have a significant effect on human eosinophils for both women and men, but with different temporal patterns, with women showing a lag of 0-5 days and men showing a lag of 20-28 days. In addition, PM2.5 was significant for women with a lag of 0-3 days but it was not significant for men. Int J Occup Med Environ Health. 2020;33(3):299-310.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Exposição Ambiental/efeitos adversos , Eosinófilos , Material Particulado/efeitos adversos , Adulto , China , Feminino , Humanos , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Dióxido de Nitrogênio/efeitos adversos , Ozônio/efeitos adversos , Tamanho da Partícula , Estudos Retrospectivos , Caracteres Sexuais
19.
EMBO Rep ; 21(6): e50164, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32250038

RESUMO

Potassium (K) is essential for plant growth and development. Here, we show that the KUP/HAK/KT K+ transporter KUP9 controls primary root growth in Arabidopsis thaliana. Under low-K+ conditions, kup9 mutants displayed a short-root phenotype that resulted from reduced numbers of root cells. KUP9 was highly expressed in roots and specifically expressed in quiescent center (QC) cells in root tips. The QC acts to maintain root meristem activity, and low-K+ conditions induced QC cell division in kup9 mutants, resulting in impaired root meristem activity. The short-root phenotype and enhanced QC cell division in kup9 mutants could be rescued by exogenous auxin treatment or by specifically increasing auxin levels in QC cells, suggesting that KUP9 affects auxin homeostasis in QC cells. Further studies showed that KUP9 mainly localized to the endoplasmic reticulum (ER), where it mediated K+ and auxin efflux from the ER lumen to the cytoplasm in QC cells under low-K+ conditions. These results demonstrate that KUP9 maintains Arabidopsis root meristem activity and root growth by regulating K+ and auxin homeostasis in response to low-K+ stress.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Ácidos Indolacéticos , Meristema/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Potássio , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Homeostase
20.
Proc Natl Acad Sci U S A ; 117(12): 6910-6917, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32152121

RESUMO

Auxin is a class of plant hormone that plays a crucial role in the life cycle of plants, particularly in the growth response of plants to ever-changing environments. Since the auxin responses are concentration-dependent and higher auxin concentrations might often be inhibitory, the optimal endogenous auxin level must be closely controlled. However, the underlying mechanism governing auxin homeostasis remains largely unknown. In this study, a UDP-glycosyltransferase (UGT76F1) was identified from Arabidopsis thaliana, which participates in the regulation of auxin homeostasis by glucosylation of indole-3-pyruvic acid (IPyA), a major precursor of the auxin indole-3-acetic acid (IAA) biosynthesis, in the formation of IPyA glucose conjugates (IPyA-Glc). In addition, UGT76F1 was found to mediate hypocotyl growth by modulating active auxin levels in a light- and temperature-dependent manner. Moreover, the transcription of UGT76F1 was demonstrated to be directly and negatively regulated by PIF4, which is a key integrator of both light and temperature signaling pathways. This study sheds a light on the trade-off between IAA biosynthesis and IPyA-Glc formation in controlling auxin levels and reveals a regulatory mechanism for plant growth adaptation to environmental changes through glucosylation of IPyA.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Regulação da Expressão Gênica de Plantas , Glucose/metabolismo , Hipocótilo/crescimento & desenvolvimento , Ácidos Indolacéticos/farmacologia , Indóis/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/metabolismo , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/metabolismo , Glucosiltransferases/metabolismo , Glicosilação , Hipocótilo/efeitos dos fármacos , Hipocótilo/metabolismo , Hipocótilo/efeitos da radiação , Indóis/química , Luz , Reguladores de Crescimento de Plantas/farmacologia , Plântula , Temperatura
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