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1.
Dokl Biochem Biophys ; 506(1): 195-201, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36303051

RESUMO

Light-dependent transcription factors GLKs of Arabidopsis thaliana are involved in the anterograde regulation of chloroplast biogenesis during deetiolation: they regulate the expression of photosynthetic nuclear-encoded genes and also mediate the transcription of plastid genes. Chloroplast biogenesis is determined at the same time by light and by endogenous factors (phytohormones), among which cytokinins significantly accelerate the formation of photosynthetically active chloroplasts. In this work, it was shown that trans-factors GLKs function as cytokinin-dependent regulators, mediating the positive cytokinin effect on the plastome expression through the activation of transcription of the SCA3 nuclear gene encoding the plastid RNA polymerase RPOTp.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Citocininas/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Estiolamento , Regulação da Expressão Gênica de Plantas , Folhas de Planta/metabolismo , Plastídeos/genética , Cloroplastos/genética , Cloroplastos/metabolismo , RNA Polimerases Dirigidas por DNA/genética , Expressão Gênica
2.
Plant Sci ; 324: 111457, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36089196

RESUMO

Photosynthesis, as an important biological process of plants, produces organic substances for plant growth and development. Although the molecular mechanisms of photosynthesis had been well investigated, the relationship between chlorophyll synthesis and photosynthesis remains largely unknown. The leaf-color mutant was an ideal material for studying photosynthesis and chlorophyll synthesis, which had been seldom investigated in tomato. Here, we obtained a yellow leaf tomato mutant ym (The mutant plants from the line of zs4) in field. Transmission electron microscopy (TEM) and photosynthetic parameters results demonstrated that chloroplast's structure was obviously destroyed and photosynthetic capacity gets weak. The mutant was hybridized with the control to construct the F2 segregation population for sequencing. Slym1 gene, controlling yellow mutant trait, was identified using Bulked Segregation Analysis. Slym1 was up-regulated in the mutant and Slym1 was located in the nucleus. The genes associated with photosynthesis and chlorophyll synthesis were down-regulated in Slym1-OE transgenic tomato plants. The results suggested that Slym1 negatively regulate photosynthesis. Photosynthetic pigment synthesis related genes HEMA, HEMB1, CHLG and CAO were up-regulated in Slym1 silencing plants. The redundant Slym1 binding the intermediate proteins MP resulting in hindering the interaction between MP and HY5 due to the Slym1 with a high expression level in ym mutant, lead to lots of the HY5 with unbound state accumulates in cells, that could accelerate the decomposition of chlorophyll. Therefore, the yellow leaf-color mutant ym could be used as an ideal material for further exploring the relationship between leaf color mutant and photosynthesis and the specific mechanism.


Assuntos
Clorofila , Lycopersicon esculentum , Clorofila/metabolismo , Estiolamento , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Fotossíntese/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/metabolismo
3.
Nat Commun ; 13(1): 4045, 2022 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-35831297

RESUMO

The conversion of light energy to chemical energy by photosynthesis requires the concerted action of large protein complexes in the thylakoid membrane. Recent work has provided fundamental insights into the three-dimensional structure of these complexes, but how they are assembled from hundreds of parts remains poorly understood. Particularly little is known about the biogenesis of the cytochrome b6f complex (Cytb6f), the redox-coupling complex that interconnects the two photosystems. Here we report the identification of a factor that guides the assembly of Cytb6f in thylakoids of chloroplasts. The protein, DE-ETIOLATION-INDUCED PROTEIN 1 (DEIP1), resides in the thylakoid membrane and is essential for photoautotrophic growth. Knock-out mutants show a specific loss of Cytb6f, and are defective in complex assembly. We demonstrate that DEIP1 interacts with the two cytochrome subunits of the complex, PetA and PetB, and mediates the assembly of intermediates in Cytb6f biogenesis. The identification of DEIP1 provides an entry point into the study of the assembly pathway of a crucial complex in photosynthetic electron transfer.


Assuntos
Arabidopsis , Complexo Citocromos b6f , Arabidopsis/genética , Arabidopsis/metabolismo , Complexo Citocromos b6f/genética , Complexo Citocromos b6f/metabolismo , Citocromos b/metabolismo , Estiolamento , Fotossíntese , Tilacoides/metabolismo
4.
Plant Cell Environ ; 45(8): 2395-2409, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35610189

RESUMO

Thylakoid FtsH complex participates in PSII repair cycle during high light-induced photoinhibition. The Arabidopsis yellow variegated2 (var2) mutants are defective in the VAR2/AtFtsH2 subunit of thylakoid FtsH complex. Taking advantage of the var2 leaf variegation phenotype, dissections of genetic enhancer loci have yielded novel paradigms in understanding functions of thylakoid FtsH complex. Here, we report the isolation of a new var2 enhancer, enhancer of variegation2-1 (evr2-1). We confirmed that EVR2 encodes a chloroplast protein that was known as BALANCE OF CHLOROPHYLL METABOLISM 1 (BCM1), or CHLOROPHYLL BIOSYNTHETIC DEFECT 1 (CBD1). We showed that EVR2/BCM1/CBD1 was involved in the oligomerization of photosystem I complexes. Genetic assays indicated that general defects in chlorophyll biosynthesis and the accumulation of photosynthetic complexes do not necessarily enhance var2 leaf variegation. In addition, we found that VAR2/AtFtsH2 is required for the accumulation of photosynthetic proteins during de-etiolation. Moreover, we identified PSII core proteins D1 and PsbC as potential EVR2-associated proteins using Co-IP/MS. Furthermore, the accumulation of D1 protein was greatly compromised in the var2-5 evr2-1 double mutant during de-etiolation. Together, our findings reveal a functional link between VAR2/AtFtsH2 and EVR2/BCM1/CBD1 in regulating chloroplast development and the accumulation of PSII reaction centre D1 protein during de-etiolation.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Proteases Dependentes de ATP/genética , Proteases Dependentes de ATP/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Clorofila/metabolismo , Cloroplastos/metabolismo , Estiolamento , Proteínas de Membrana/metabolismo , Mutação/genética , Complexo de Proteína do Fotossistema II/metabolismo
6.
New Phytol ; 235(1): 188-203, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35322876

RESUMO

One of the most dramatic challenges in the life of a plant occurs when the seedling emerges from the soil and exposure to light triggers expression of genes required for establishment of photosynthesis. This process needs to be tightly regulated, as premature accumulation of light-harvesting proteins and photoreactive Chl precursors causes oxidative damage when the seedling is first exposed to light. Photosynthesis genes are encoded by both nuclear and plastid genomes, and to establish the required level of control, plastid-to-nucleus (retrograde) signalling is necessary to ensure correct gene expression. We herein show that a negative GENOMES UNCOUPLED1 (GUN1)-mediated retrograde signal restricts chloroplast development in darkness and during early light response by regulating the transcription of several critical transcription factors linked to light response, photomorphogenesis, and chloroplast development, and consequently their downstream target genes in Arabidopsis. Thus, the plastids play an essential role during skotomorphogenesis and the early light response, and GUN1 acts as a safeguard during the critical step of seedling emergence from darkness.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Ligação a DNA/metabolismo , Estiolamento , Regulação da Expressão Gênica de Plantas , Plastídeos/genética , Plastídeos/metabolismo , Plântula/genética , Plântula/metabolismo
7.
Plant Physiol ; 189(3): 1728-1740, 2022 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-35357495

RESUMO

In etiolated seedlings, red light (R) activates phytochrome and initiates signals that generate major changes at molecular and physiological levels. These changes include inhibition of hypocotyl growth and promotion of the growth of primary roots, apical hooks, and cotyledons. An earlier report showed that the sharp decrease in hypocotyl growth rapidly induced by R was accompanied by an equally rapid decrease in the transcript and protein levels of two closely related apyrases (APYs; nucleoside triphosphate-diphosphohydrolases) in Arabidopsis (Arabidopsis thaliana), APY1 and APY2, enzymes whose expression alters auxin transport and growth in seedlings. Here, we report that single knockouts of either APY inhibit R-induced promotion of the growth of primary roots, apical hooks, and cotyledons, and RNAi-induced suppression of APY1 expression in the background of apy2 inhibits R-induced apical hook opening. When R-irradiated primary roots and apical hook-cotyledons began to show a gradual increase in their growth relative to dark controls, they concurrently showed increased levels of APY protein, but in hook-cotyledon tissue, this occurred without parallel increases in their transcripts. In wild-type seedlings whose root growth is suppressed by the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea, the R-induced increased APY expression in roots was also inhibited. In unirradiated plants, the constitutive expression of APY2 promoted both hook opening and changes in the transcript abundance of Small Auxin Upregulated RNA (SAUR), SAUR17 and SAUR50 that help mediate de-etiolation. These results provide evidence that the expression of APY1/APY2 is regulated by R and that APY1/APY2 participate in the signaling pathway by which phytochrome induces differential growth changes in different tissues of etiolated seedlings.


Assuntos
Apirase/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis , Fitocromo , Arabidopsis/fisiologia , Estiolamento , Hipocótilo , Ácidos Indolacéticos/metabolismo , Ácidos Indolacéticos/farmacologia , Luz , Fitocromo/genética , Fitocromo/metabolismo , Plântula/metabolismo
8.
Plant J ; 108(2): 459-477, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34365695

RESUMO

Autophagy is a conserved catabolic process that plays an essential role under nutrient starvation conditions and influences different developmental processes. We observed that seedlings of autophagy mutants (atg2, atg5, atg7, and atg9) germinated in the dark showed delayed chloroplast development following illumination. The delayed chloroplast development was characterized by a decrease in photosynthetic and chlorophyll biosynthetic proteins, lower chlorophyll content, reduced chloroplast size, and increased levels of proteins involved in lipid biosynthesis. Confirming the biological impact of these differences, photosynthetic performance was impaired in autophagy mutants 12 h post-illumination. We observed that while gene expression for photosynthetic machinery during de-etiolation was largely unaffected in atg mutants, several genes involved in photosystem assembly were transcriptionally downregulated. We also investigated if the delayed chloroplast development could be explained by lower lipid import to the chloroplast or lower triglyceride (TAG) turnover. We observed that the limitations in the chloroplast lipid import imposed by trigalactosyldiacylglycerol1 are unlikely to explain the delay in chloroplast development. However, we found that lower TAG mobility in the triacylglycerol lipase mutant sugardependent1 significantly affected de-etiolation. Moreover, we showed that lower levels of carbon resources exacerbated the slow greening phenotype whereas higher levels of carbon resources had an opposite effect. This work suggests a lack of autophagy machinery limits chloroplast development during de-etiolation, and this is exacerbated by limited lipid turnover (lipophagy) that physically or energetically restrains chloroplast development.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Autofagia/genética , Carbono/metabolismo , Cloroplastos/fisiologia , Aminopeptidases/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Relacionadas à Autofagia/genética , Hidrolases de Éster Carboxílico/genética , Cloroplastos/metabolismo , Escuridão , Estiolamento , Regulação da Expressão Gênica de Plantas , Luz , Metabolismo dos Lipídeos/genética , Proteínas de Membrana Transportadoras/genética , Mutação , Fotossíntese/genética , Plântula/genética , Plântula/fisiologia
9.
Nat Commun ; 12(1): 4194, 2021 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-34234144

RESUMO

Photomorphogenesis, light-mediated development, is an essential feature of all terrestrial plants. While chloroplast development and brassinosteroid (BR) signaling are known players in photomorphogenesis, proteins that regulate both pathways have yet to be identified. Here we report that DE-ETIOLATION IN THE DARK AND YELLOWING IN THE LIGHT (DAY), a membrane protein containing DnaJ-like domain, plays a dual-role in photomorphogenesis by stabilizing the BR receptor, BRI1, as well as a key enzyme in chlorophyll biosynthesis, POR. DAY localizes to both the endomembrane and chloroplasts via its first transmembrane domain and chloroplast transit peptide, respectively, and interacts with BRI1 and POR in their respective subcellular compartments. Using genetic analysis, we show that DAY acts independently on BR signaling and chlorophyll biogenesis. Collectively, this work uncovers DAY as a factor that simultaneously regulates BR signaling and chloroplast development, revealing a key regulator of photomorphogenesis that acts across cell compartments.


Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Membrana/metabolismo , Morfogênese/fisiologia , Proteínas Quinases/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Brassinosteroides/metabolismo , Clorofila/biossíntese , Cloroplastos/metabolismo , Estiolamento/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP40/isolamento & purificação , Luz , Proteínas de Membrana/genética , Proteínas de Membrana/isolamento & purificação , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Morfogênese/efeitos da radiação , Mutação , Plantas Geneticamente Modificadas , Proteínas Quinases/genética , RNA-Seq , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Plântula/crescimento & desenvolvimento , Transdução de Sinais/fisiologia
10.
Int J Mol Sci ; 22(7)2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33804852

RESUMO

Light is the primary regulator of various biological processes during the plant life cycle. Although plants utilize photosynthetically active radiation to generate chemical energy, they possess several photoreceptors that perceive light of specific wavelengths and then induce wavelength-specific responses. Light is also one of the key determinants of the initiation of leaf senescence, the last stage of leaf development. As the leaf photosynthetic activity decreases during the senescence phase, chloroplasts generate a variety of light-mediated retrograde signals to alter the expression of nuclear genes. On the other hand, phytochrome B (phyB)-mediated red-light signaling inhibits the initiation of leaf senescence by repressing the phytochrome interacting factor (PIF)-mediated transcriptional regulatory network involved in leaf senescence. In recent years, significant progress has been made in the field of leaf senescence to elucidate the role of light in the regulation of nuclear gene expression at the molecular level during the senescence phase. This review presents a summary of the current knowledge of the molecular mechanisms underlying light-mediated regulation of leaf senescence.


Assuntos
Folhas de Planta/crescimento & desenvolvimento , Luz Solar , Estiolamento , Fotossíntese , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais
11.
Methods Mol Biol ; 2297: 49-60, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33656669

RESUMO

Seedlings grown in darkness exhibit distinct morphologies comparing with light-grown seedlings. Elongated hypocotyls, closed yellow cotyledons, and the formation of apical hooks are typical characteristics for etiolated seedlings, which are collectively named skotomorphogenesis. Various plant hormones and environmental factors are essential for maintaining skotomorphogenesis. Due to the diverse morphological outcomes in etiolated seedlings grown under different treatments, studies on skotomorphogenesis are of particular importance to reveal the molecular mechanisms underlying plant response to environmental cues. Here, we detailed experimental procedures to facilitate researchers who are investigating etiolation growth-related studies.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Estiolamento/efeitos dos fármacos , Reguladores de Crescimento de Plantas/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Cotilédone/efeitos dos fármacos , Cotilédone/genética , Cotilédone/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Hipocótilo/efeitos dos fármacos , Hipocótilo/genética , Hipocótilo/crescimento & desenvolvimento , Temperatura
12.
Methods Mol Biol ; 2297: 95-103, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33656673

RESUMO

Seedling deetiolation is a hallmark of the photomorphogenic response, and successful conversion of protochlorophyllide (Pchlide) into chlorophyllide during initial light exposure is critical for plant survival and growth. Here we describe the seedling deetiolation process of two typical mutants pif3 and flu by analysis of the cotyledons greening, Pchlide content, and reactive oxygen species (ROS) production and summarize a set of general methods for the research of seedling greening.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Protoclorifilida/metabolismo , Arabidopsis/química , Arabidopsis/genética , Clorofilídeos/metabolismo , Estiolamento , Regulação da Expressão Gênica de Plantas , Mutação , Espécies Reativas de Oxigênio/metabolismo , Plântula/química , Plântula/genética , Plântula/crescimento & desenvolvimento
13.
New Phytol ; 231(3): 1023-1039, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33666236

RESUMO

Arabidopsis histone H3 lysine 4 (H3K4) demethylases play crucial roles in several developmental processes, but their involvement in seedling establishment remain unexplored. Here, we show that Arabidopsis JUMONJI DOMAIN-CONTAINING PROTEIN17 (JMJ17), an H3K4me3 demethylase, is involved in cotyledon greening during seedling establishment. Dark-grown seedlings of jmj17 accumulated a high concentration of protochlorophyllide, an intermediate metabolite in the tetrapyrrole biosynthesis (TPB) pathway that generates chlorophyll (Chl) during photomorphogenesis. Upon light irradiation, jmj17 mutants displayed decreased cotyledon greening and reduced Chl level compared with the wild-type; overexpression of JMJ17 completely rescued the jmj17-5 phenotype. Transcriptomics analysis uncovered that several genes encoding key enzymes involved in TPB were upregulated in etiolated jmj17 seedlings. Consistently, chromatin immunoprecipitation-quantitative PCR revealed elevated H3K4me3 level at the promoters of target genes. Chromatin association of JMJ17 was diminished upon light exposure. Furthermore, JMJ17 interacted with PHYTOCHROME INTERACTING FACTOR1 in the yeast two-hybrid assay. JMJ17 binds directly to gene promoters to demethylate H3K4me3 to suppress PROTOCHLOROPHYLLIDE OXIDOREDUCTASE C expression and TPB in the dark. Light results in de-repression of gene expression to modulate seedling greening during de-etiolation. Our study reveals a new role for histone demethylase JMJ17 in controlling cotyledon greening in etiolated seedlings during the dark-to-light transition.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Clorofila , Cotilédone/genética , Cotilédone/metabolismo , Estiolamento , Regulação da Expressão Gênica de Plantas , Luz , Plântula/genética , Plântula/metabolismo
14.
J Plant Physiol ; 260: 153409, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33774509

RESUMO

Sugar accumulation in maize (Zea mays) coleoptile and mesocotyl cells was suppressed when etiolated seedlings were subjected to white light irradiation. Regulation mechanisms of sugar accumulation by light in cells of both organs were studied. Sucrose exudation from the endosperm was suppressed in light-treated seedlings. In addition, the activities and transcript levels of sucrose-phosphate synthase (SPS) in scutella were decreased following light irradiation. These results suggest that sucrose exudation from the endosperm is decreased by the suppression of SPS activities via downregulation of its gene expression. In coleoptiles and mesocotyls, light irradiation also decreased the activities and transcript levels of cell wall-bound invertase, suggesting that phloem unloading processes were suppressed. Thus, inhibition of both sucrose loading from the endosperm and sucrose unloading in coleoptiles and mesocotyls may be involved in the suppression of sugar accumulation in coleoptiles and mesocotyls irradiated with white light.


Assuntos
Cotilédone/metabolismo , Estiolamento , Luz , Sacarose/metabolismo , Zea mays/metabolismo , Plântula/metabolismo , Plântula/efeitos da radiação , Zea mays/efeitos da radiação
15.
Elife ; 102021 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-33629953

RESUMO

Light triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Using Serial Block Face Scanning Electron Microscopy (SBF-SEM), we generated a series of chloroplast 3D reconstructions during differentiation, revealing chloroplast number and volume and the extent of envelope and thylakoid membrane surfaces. Furthermore, we used quantitative lipid and whole proteome data to complement the (ultra)structural data, providing a time-resolved, multi-dimensional description of chloroplast differentiation. This showed two distinct phases of chloroplast biogenesis: an initial photosynthesis-enabling 'Structure Establishment Phase' followed by a 'Chloroplast Proliferation Phase' during cell expansion. Moreover, these data detail thylakoid membrane expansion during de-etiolation at the seedling level and the relative contribution and differential regulation of proteins and lipids at each developmental stage. Altogether, we establish a roadmap for chloroplast differentiation, a critical process for plant photoautotrophic growth and survival.


Assuntos
Arabidopsis/fisiologia , Cloroplastos/fisiologia , Estiolamento , Biogênese de Organelas
16.
Sci China Life Sci ; 64(5): 816-827, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-32712832

RESUMO

The vital function of mitochondrial alternative oxidase (AOX) pathway in optimizing photosynthesis during plant de-etiolation has been well recognized. However, whether and how AOX impacts the chloroplast biogenesis in algal cells remains unclear. In the present study, the role of AOX in regulating the reassembly of chloroplast in algal cells was investigated by treating Auxenochlorella protothecoides with salicylhydroxamic acid (SHAM), the specific inhibitor to AOX, in the heterotrophy to autotrophy transition process. Several lines of evidences including delayed chlorophyll accumulation, lagged reorganization of chloroplast structure, altered PSI/PSII stoichiometry, and declined photosynthetic activities in SHAM treated cells indicated that the impairment in AOX activity dramatically hindered the development of functioning chloroplast in algal cells. Besides, the cellular ROS levels and activities of antioxidant enzymes were increased by SHAM treatment, and the perturbation on the balance of NAD+/NADH and NADP+/NADPH ratios was also observed in A. protothecoides lacking AOX activity, indicating that AOX was essential in promoting ROS scavenging and keeping the redox homeostasis for algal chloroplast development during greening. Overall, our study revealed the essentiality of mitochondrial AOX pathway in sustaining algal photosynthetic performance and provided novel insights into the physiological roles of AOX on the biogenesis of photosynthetic organelle in algae.


Assuntos
Clorofila/metabolismo , Cloroplastos/metabolismo , Estiolamento/fisiologia , Microalgas/metabolismo , Proteínas Mitocondriais/metabolismo , Oxirredutases/metabolismo , Fotossíntese/fisiologia , Proteínas de Plantas/metabolismo , Salicilamidas
17.
Chemosphere ; 267: 128918, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33218729

RESUMO

Antibiotic pollution has become an important global issue, and ofloxacin (OFL) is widely used worldwide. However, little is known about the potential adverse effects of OFL on plants. We assessed the toxic effects of OFL on Welsh onion and explored its toxicity mechanism. The leaf pigment content increased in 0.1 mg/L of OFL but decreased in a dose-dependent manner (0.5-2 mg/L OFL) until leaf etiolation. The ultrastructure of leaves showed that the treatment of 2 mg/L OFL produced significant toxicity. Furthermore, photosynthetic and fluorescence parameters were negatively affected by OFL treatment. The photosynthetic electron transport chain was significantly inhibited by OFL treatment, especially between QA and QB. The hydrogen peroxide and malondialdehyde content also increased with OFL concentration, indicating that antioxidant enzymes' role in antibiotic response is limited. In conclusion, OFL can damage chloroplasts by promoting ROS accumulation, which results in the etiolation of Welsh onion leaves.


Assuntos
Ofloxacino , Cebolas , Antibacterianos/toxicidade , Estiolamento , Ofloxacino/toxicidade , Fotossíntese , Folhas de Planta
18.
Int J Mol Sci ; 21(21)2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33126662

RESUMO

Vanilla orchid, which is well-known for its flavor and fragrance, is cultivated in tropical and subtropical regions. This shade-loving plant is very sensitive to high irradiance. In this study, we show that vanilla chloroplasts started to have avoidance movement when blue light (BL) was higher than 20 µmol m-2s-1 and significant avoidance movement was observed under BL irradiation at 100 µmol m-2s-1 (BL100). The light response curve indicated that when vanilla was exposed to 1000 µmol m-2s-1, the electron transport rate (ETR) and photochemical quenching of fluorescence (qP) were significantly reduced to a negligible amount. We found that if a vanilla orchid was irradiated with BL100 for 12 days, it acquired BL-acclimation. Chloroplasts moved to the side of cells in order to reduce light-harvesting antenna size, and chloroplast photodamage was eliminated. Therefore, BL-acclimation enhanced vanilla orchid growth and tolerance to moderate (500 µmol m-2s-1) and high light (1000 µmol m-2s-1) stress conditions. It was found that under high irradiation, BL-acclimatized vanilla maintained higher ETR and qP capacity than the control without BL-acclimation. BL-acclimation induced antioxidant enzyme activities, reduced ROS accumulation, and accumulated more carbohydrates. Moreover, BL-acclimatized orchids upregulated photosystem-II-associated marker genes (D1 and PetC), Rubisco and PEPC transcripts and sustained expression levels thereof, and also maximized the photosynthesis rate. Consequently, BL-acclimatized orchids had higher biomass. In short, this study found that acclimating vanilla orchid with BL before transplantation to the field might eliminate photoinhibition and enhance vanilla growth and production.


Assuntos
Clorofila/metabolismo , Cloroplastos/metabolismo , Estiolamento , Luz , Fotossíntese , Vanilla/crescimento & desenvolvimento , Cloroplastos/efeitos da radiação , Fluorescência , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/efeitos da radiação , Vanilla/metabolismo , Vanilla/efeitos da radiação
19.
Plant Cell ; 32(12): 3792-3811, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33093148

RESUMO

Following germination in the dark, Arabidopsis (Arabidopsis thaliana) seedlings undergo etiolation and develop apical hooks, closed cotyledons, and rapidly elongating hypocotyls. Upon light perception, the seedlings de-etiolate, which includes the opening of apical hooks and cotyledons. Here, we identify Arabidopsis Small Auxin Up RNA17 (SAUR17) as a downstream effector of etiolation, which serves to bring about apical hook formation and closed cotyledons. SAUR17 is highly expressed in apical hooks and cotyledons and is repressed by light. The apical organs also express a group of light-inducing SAURs, as represented by SAUR50, which promote hook and cotyledon opening. The development of etiolated or de-etiolated apical structures requires asymmetric differential cell growth. We present evidence that the opposing actions of SAUR17 and SAUR50 on apical development largely result from their antagonistic regulation of Protein Phosphatase 2C D-clade 1 (PP2C-D1), a phosphatase that suppresses cell expansion and promotes apical hook development in the dark. SAUR50 inhibits PP2C-D1, whereas SAUR17 has a higher affinity for PP2C-D1 without inhibiting its activity. PP2C-D1 predominantly associates with SAUR17 in etiolated seedlings, which shields it from inhibitory SAURs such as SAUR50. Light signals turn off SAUR17 and upregulate a subgroup of SAURs including SAUR50 at the inner side of the hook and cotyledon cells, leading to cell expansion and unfolding of the hook and cotyledons.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Transdução de Sinal Luminoso , Reguladores de Crescimento de Plantas/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Cotilédone/genética , Cotilédone/crescimento & desenvolvimento , Cotilédone/fisiologia , Etilenos/metabolismo , Estiolamento , Genes Reporter , Ácidos Indolacéticos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Luz , Proteína Fosfatase 2C/genética , Proteína Fosfatase 2C/metabolismo , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Regulação para Cima
20.
Planta ; 252(5): 74, 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33025156

RESUMO

MAIN CONCLUSION: In general, genes promoting IAA, CTK GA and ethylene biosynthesis were upregulated, while genes participating in ABA, chlorophyll and starch biosynthesis pathways performed opposite tendency during etiolation. Etiolation as a method for rejuvenation plays an important role in the vegetative propagation of woody plants. However, the molecular mechanism of etiolated shoot development remains unclear. In this study, we investigated changes at different etiolation stages of Juglans regia. The histology and transcriptome of J. regia were analysed using etiolated stems, which were treated in darkness for 30, 60, 90 days. The results showed that the ratios of pith (Pi) diameter/stem diameter (D), cortex (Co) width/D, and phloem (Ph) width/D increased, while the ratio of xylem (Xy) width/D decreased after etiolation, and the difference in these ratios between etiolated stems and the control was more significant at 60 days than 90 days. Differentially expressed genes (DEGs) were significantly enriched in pathways such as plant hormone biosynthesis and signal transduction, chlorophyll biosynthesis and degradation, and starch and sucrose metabolism. The difference in the contents of indole-3-acetic acid (IAA), abscisic acid (ABA), sugar and chlorophyll between etiolated stems and the control increased with increasing treatment duration; in contrast, the concentrations of gibberellin (GA), zeatin (ZT), and starch, as well as the difference between the etiolated stems and control were lowest at 60 days among the three stages. On the whole, the positive effect of etiolation on the rejuvenation of walnut stems changed as the treatment period increased. The present investigation lays a foundation for future studies on the effect of etiolation on rejuvenation and for promoting the efficiency of vegetative propagation.


Assuntos
Juglans , Brotos de Planta , Transcriptoma , Estiolamento , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Juglans/genética , Juglans/crescimento & desenvolvimento , Reguladores de Crescimento de Plantas/metabolismo , Brotos de Planta/crescimento & desenvolvimento , Transcriptoma/genética
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