RESUMEN
Drought stress caused by the global climate considerably disturbs plant yield and growth. Here, we explored the putative roles of silicon in repressing drought mechanisms in pepper and the prominent involvement of secondary metabolites, GA pathway, and photosystem II. Our research revealed that the transcript level of the flavonoid biosynthesis-associated genes, including the PAL, 4-CL, CHS, FLS-1, F3H and DFR, progressively induced in the pepper leaves treated with silicon during the drought stress duration. Moreover, the phenolic and flavonoid compounds extensively induced in the pepper plants. Furthermore, the pepper plants markedly inhibited chlorophyll catabolic-allied genes, senescence-related marker gene, and the Rbohs gene. Silicon application also sustained the membrane stability, supported via fewer electrolyte leakage processes and minor, O2- H2O2 and MDA levels during drought. Apart from this, the pepper plants significantly induced the expression level of the photosystem II-related genes, osmoprotectants pathway-associated genes, and antioxidant defense genes. Moreover, the GA biosynthesis genes were prompted, while the ABA signaling and biosynthesis genes were suppressed in the silicon-supplemented plants. These consequences infer that the role of Si supplementation on enhancing drought tolerance could be elucidated through the activation of secondary metabolites, flavonoid biosynthesis, osmoprotectants, GA pathway, the efficiency of PSII, and the suppression of chlorophyll degradation. Our research outcomes unveil new and remarkable characteristics of silicon supplementation and offer a series of candidate targets for improving the tolerance of pepper plants to drought stress.
Asunto(s)
Capsicum , Clorofila , Resistencia a la Sequía , Silicio , Capsicum/metabolismo , Capsicum/genética , Capsicum/efectos de los fármacos , Capsicum/fisiología , Clorofila/metabolismo , Clorofila/biosíntesis , Resistencia a la Sequía/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Complejo de Proteína del Fotosistema II/metabolismo , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de los fármacos , Silicio/farmacología , Silicio/metabolismoRESUMEN
Ethylene produced by plants generally induces ripening and promotes decay, whereas the effect of ethylene produced by pathogens on plant diseases remains unclear. In this study, four ethylene-producing fungi including Alternaria alternata (A. alternata, Aa), Fusarium verticilliodes (F. verticillioides, Fv), Fusarium fujikuroi 1 (F. fujikuroi 1, Ff-1) and Fusarium fujikuroi 2 (F. fujikuroi 2, Ff-2) were severally inoculated in potato dextrose broth (PDB) media and postharvest green peppers, the ethylene production rates, disease indexes and chlorophyll fluorescence parameters were determined. The results showed that Ff-2 and Fv in the PDB media had the highest and almost the same ethylene production rates. After inoculation with green peppers, Ff-2 treated group still exhibited the highest ethylene production rate, whereas Aa treated group had a weak promotion effect on ethylene production. Moreover, the ethylene production rate of green peppers with mechanical injury was twice that without mechanical injury, and the ethylene production rates of green peppers treated with Aa, Ff-1, Ff-2 and Fv were 1.2, 2.6, 3.8 and 2.8 folds than those of green peppers without treatment, respectively. These results indicated that pathogen infection stimulated the synthesis of ethylene in green peppers. Correlation analysis indicated that the degreening of Fusarium-infected green pepper was significantly positively correlated with the ethylene production rate of green pepper, whereas the disease spot of Aa-infected green pepper had a significant positive correlations with the ethylene production rate of green peppers. Chlorophyll fluorescence results showed that the green peppers already suffered from severe disease after being infected with fungi for 4 days, and Fusarium infection caused early and serious stress, while the harm caused by A. alternata was relatively mild at the early stage. Our results clearly showed that α-keto-γ-methylthiobutyric acid (KMBA)-mediated ethylene synthesis was the major ethylene synthesis pathway in the four postharvest pathogenic fungi. All the results obtained suggested that ethylene might be the main infection factor of Fusarium spp. in green peppers. For pathogenic fungi, stimulating green peppers to produce high level of ethylene played a key role in the degreening of green peppers.
Asunto(s)
Alternaria , Capsicum , Etilenos , Fusarium , Enfermedades de las Plantas , Etilenos/metabolismo , Etilenos/biosíntesis , Capsicum/microbiología , Fusarium/metabolismo , Enfermedades de las Plantas/microbiología , Alternaria/metabolismo , Clorofila/metabolismo , Clorofila/biosíntesisRESUMEN
As one of the largest and most diverse classes of specialized metabolites in plants, terpenoids (oprenoid compounds, a type of bio-based material) are widely used in the fields of medicine and light chemical products. They are the most important secondary metabolites in coniferous species and play an important role in the defense system of conifers. Terpene synthesis can be promoted by regulating the expressions of terpene synthase genes, and the terpene biosynthesis pathway has basically been clarified in Pinus massoniana, in which there are multiple rate-limiting enzymes and the rate-limiting steps are difficult to determine, so the terpene synthase gene regulation mechanism has become a hot spot in research. Herein, we amplified a PmDXR gene (GenBank accession no. MK969119.1) of the MEP pathway (methyl-erythritol 4-phosphate) from Pinus massoniana. The DXR enzyme activity and chlorophyll a, chlorophyll b and carotenoid contents of overexpressed Arabidopsis showed positive regulation. The PmDXR gene promoter was a tissue-specific promoter and can respond to ABA, MeJA and GA stresses to drive the expression of the GUS reporter gene in N. benthamiana. The DXR enzyme was identified as a key rate-limiting enzyme in the MEP pathway and an effective target for terpene synthesis regulation in coniferous species, which can further lay the theoretical foundation for the molecularly assisted selection of high-yielding lipid germplasm of P. massoniana, as well as provide help in the pathogenesis of pine wood nematode disease.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Pinus , Proteínas de Plantas , Trementina , Ácido Abscísico/metabolismo , Acetatos/metabolismo , Transferasas Alquil y Aril/genética , Transferasas Alquil y Aril/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Vías Biosintéticas , Carotenoides/metabolismo , Clorofila/metabolismo , Clorofila/biosíntesis , Clorofila A/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Pinus/genética , Pinus/metabolismo , Pinus/parasitología , Pinus/enzimología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Regiones Promotoras Genéticas , Terpenos/metabolismo , Trementina/química , Trementina/metabolismoRESUMEN
Reduction of the 17,18-double bond in the D-ring during chlorophyll biosynthesis is catalyzed by the rare, naturally occurring photoenzyme protochlorophyllide oxidoreductase (POR). A conserved tyrosine residue has been suggested to donate a proton to C18 of the substrate in the past decades. Taylor and colleagues scrutinized the model with a powerful tool that utilized a modified genetic code to introduce fluorinated tyrosine analogues into POR. The presented results show that the suggested catalytically critical tyrosine is unlikely to participate in the reaction chemistry but is required for substrate binding, and instead, a cysteine residue preceding the lid helix is proposed to have the role of proton donor.
Asunto(s)
Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH , Protoclorofilida , Halogenación , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/química , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/genética , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/metabolismo , Protoclorofilida/química , Protones , Clorofila/biosíntesis , Clorofila/metabolismoRESUMEN
Rapeseed (Brassica napus L.) is mainly used for oil production and industrial purposes. A high photosynthetic efficiency is the premise of a high yield capable of meeting people's various demands. Chlorophyll-deficient mutants are ideal materials for studying chlorophyll biosynthesis and photosynthesis. In a previous study, we obtained the mutant yl1 for leaf yellowing throughout the growth period by ethyl methanesulfonate mutagenesis of B. napus. A genetic analysis showed that the yl1 chlorophyll-deficient phenotype was controlled by one incompletely dominant gene, which was mapped on chromosome A03 by a quantitative trait loci sequencing analysis and designated as BnA03.Chd in this study. We constructed an F2 population containing 5256 individuals to clone BnA03.Chd. Finally, BnA03.Chd was fine-mapped to a 304.7 kb interval of the B. napus 'ZS11' genome containing 58 annotated genes. Functional annotation, transcriptome, and sequence variation analyses confirmed that BnaA03g0054400ZS, a homolog of AT5G13630, was the most likely candidate gene. BnaA03g0054400ZS encodes the H subunit of Mg-chelatase. A sequence analysis revealed a single-nucleotide polymorphism (SNP), causing an amino-acid substitution from glutamic acid to lysine (Glu1349Lys). In addition, the molecular marker BnaYL1 was developed based on the SNP of BnA03.Chd, which perfectly cosegregated with the chlorophyll-deficient phenotype in two different F2 populations. Our results provide insight into the molecular mechanism underlying chlorophyll synthesis in B. napus.
Asunto(s)
Brassica napus , Clorofila , Brassica napus/genética , Clorofila/biosíntesis , Mapeo Cromosómico/métodos , Genes de Plantas , Fotosíntesis , Sitios de Carácter CuantitativoRESUMEN
In photoautotrophic Synechocystis sp. PCC 6803, NADPH is generated from photosynthesis and utilized in various metabolism, including the biosynthesis of glyceraldehyde 3-phosphate (the upstream substrate for carbon metabolism), poly(3-hydroxybutyrate) (PHB), photosynthetic pigments, and hydrogen gas (H2). Redirecting NADPH flow from one biosynthesis pathway to another has yet to be studied. Synechocystis's H2 synthesis, one of the pathways consuming NAD(P)H, was disrupted by the inactivation of hoxY and hoxH genes encoding the two catalytic subunits of hydrogenase. Such inactivation with a complete disruption of H2 synthesis led to 1.4-, 1.9-, and 2.1-fold increased cellular NAD(P)H levels when cells were cultured in normal medium (BG11), the medium without nitrate (-N), and the medium without phosphate (-P), respectively. After 49-52 d of cultivation in BG11 (when the nitrogen source in the media was depleted), the cells with disrupted H2 synthesis had 1.3-fold increased glycogen level compared to wild type of 83-85% (w/w dry weight), the highest level reported for cyanobacterial glycogen. The increased glycogen content observed by transmission electron microscopy was correlated with the increased levels of glucose 6-phosphate and glucose 1-phosphate, the two substrates in glycogen synthesis. Disrupted H2 synthesis also enhanced PHB accumulation up to 1.4-fold under -P and 1.6-fold under -N and increased levels of photosynthetic pigments (chlorophyll a, phycocyanin, and allophycocyanin) by 1.3- to 1.5-fold under BG11. Thus, disrupted H2 synthesis increased levels of NAD(P)H, which may be utilized for the biosynthesis of glycogen, PHB, and pigments. This strategy might be applicable for enhancing other biosynthetic pathways that utilize NAD(P)H.
Asunto(s)
Clorofila/biosíntesis , Glucógeno/biosíntesis , Hidrógeno/metabolismo , Hidroxibutiratos/metabolismo , NADP/metabolismo , Synechocystis/química , Synechocystis/genética , Synechocystis/metabolismo , Clorofila/genética , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Glucógeno/genética , Redes y Vías Metabólicas , NADP/genéticaRESUMEN
The papain-like cysteine proteases (PLCPs), the most important group of cysteine proteases, have been reported to participate in the regulation of growth, senescence, and abiotic stresses in plants. However, the functions of PLCPs and their roles in stress response in microalgae was rarely reported. The responses to different abiotic stresses in Haematococcus pluvialis were often observed, including growth regulation and astaxanthin accumulation. In this study, the cDNA of HpXBCP3 containing 1515 bp open reading frame (ORF) was firstly cloned from H. pluvialis by RT-PCR. The analysis of protein domains and molecular evolution showed that HpXBCP3 was closely related to AtXBCP3 from Arabidopsis. The expression pattern analysis revealed that it significantly responds to NaCl stress in H. pluvialis. Subsequently, transformants expressing HpXBCP3 in Chlamydomonas reinhardtii were obtained and subjected to transcriptomic analysis. Results showed that HpXBCP3 might affect the cell cycle regulation and DNA replication in transgenic Chlamydomonas, resulting in abnormal growth of transformants. Moreover, the expression of HpXBCP3 might increase the sensitivity to NaCl stress by regulating ubiquitin and the expression of WD40 proteins in microalgae. Furthermore, the expression of HpXBCP3 might improve chlorophyll content by up-regulating the expression of NADH-dependent glutamate synthases in C. reinhardtii. This study indicated for the first time that HpXBCP3 was involved in the regulation of cell growth, salt stress response, and chlorophyll synthesis in microalgae. Results in this study might enrich the understanding of PLCPs in microalgae and provide a novel perspective for studying the mechanism of environmental stress responses in H. pluvialis.
Asunto(s)
Proteínas Algáceas/metabolismo , Chlorophyceae/enzimología , Proteasas de Cisteína/metabolismo , Microalgas/crecimiento & desarrollo , Microalgas/fisiología , Proteínas Algáceas/química , Proteínas Algáceas/genética , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/crecimiento & desarrollo , Chlamydomonas reinhardtii/fisiología , Chlorophyceae/genética , Clorofila/biosíntesis , Proteasas de Cisteína/química , Proteasas de Cisteína/genética , Perfilación de la Expresión Génica , Regulación de la Expresión Génica , Ontología de Genes , Redes y Vías Metabólicas/genética , Redes y Vías Metabólicas/fisiología , Microalgas/genética , Filogenia , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Tolerancia a la Sal/genética , Tolerancia a la Sal/fisiología , Estrés Fisiológico/genética , Estrés Fisiológico/fisiología , Transformación GenéticaRESUMEN
Chokecherry (Padus virginiana L.) is an important landscaping tree with high ornamental value because of its colorful purplish-red leaves (PRL). The quantifications of anthocyanins and the mechanisms of leaf color change in this species remain unknown. The potential biosynthetic and regulatory mechanisms and the accumulation patterns of anthocyanins in P. virginiana that determine three leaf colors were investigated by combined analysis of the transcriptome and the metabolome. The difference of chlorophyll, carotenoid and anthocyanin content correlated with the formation of P. virginiana leaf color. Using enrichment and correlation network analysis, we found that anthocyanin accumulation differed in different colored leaves and that the accumulation of malvidin 3-O-glucoside (violet) and pelargonidin 3-O-glucoside (orange-red) significantly correlated with the leaf color change from green to purple-red. The flavonoid biosynthesis genes (PAL, CHS and CHI) and their transcriptional regulators (MYB, HD-Zip and bHLH) exhibited specific increased expression during the purple-red periods. Two genes encoding enzymes in the anthocyanin biosynthetic pathway, UDP glucose-flavonoid 3-O-glucosyl-transferase (UFGT) and anthocyanidin 3-O-glucosyltransferase (BZ1), seem to be critical for suppressing the formation of the aforesaid anthocyanins. In PRL, the expression of the genes encoding for UGFT and BZ1 enzymes was substantially higher than in leaves of other colors and may be related with the purple-red color change. These results may facilitate genetic modification or selection for further improvement in ornamental qualities of P. virginiana.
Asunto(s)
Antocianinas/biosíntesis , Pigmentación , Hojas de la Planta/metabolismo , Prunus/fisiología , Vías Biosintéticas , Clorofila/biosíntesis , Color , Biología Computacional/métodos , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Metaboloma , Metabolómica/métodos , Pigmentación/genética , Hojas de la Planta/genética , TranscriptomaRESUMEN
The assembly of light-harvesting chlorophyll-binding proteins (LHCPs) is coordinated with chlorophyll biosynthesis during chloroplast development. The ATP-independent chaperone known as chloroplast signal recognition particle 43 (cpSRP43) mediates post-translational LHCP targeting to the thylakoid membrane and also participates in tetrapyrrole biosynthesis (TBS). How these distinct actions of cpSRP43 are controlled has remained unclear. Here, we demonstrate that cpSRP43 effectively protects several TBS proteins from heat-induced aggregation and enhances their stability during leaf greening and heat shock. While the substrate-binding domain of cpSRP43 is sufficient for chaperoning LHCPs, the stabilization of TBS clients requires the chromodomain 2 of the protein. Strikingly, cpSRP54-which activates cpSRP43's LHCP-targeted function-inhibits the chaperone activity of cpSRP43 towards TBS proteins. High temperature weakens the interaction of cpSRP54 with cpSRP43, thus freeing cpSRP43 to interact with and protect the integrity of TBS proteins. Our data indicate that the temperature sensitivity of the cpSRP43-cpSRP54 complex enables cpSRP43 to serve as an autonomous chaperone for the thermoprotection of TBS proteins.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/fisiología , Clorofila/biosíntesis , Respuesta al Choque Térmico/genética , Partícula de Reconocimiento de Señal/genética , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Clorofila/genética , Partícula de Reconocimiento de Señal/metabolismoRESUMEN
Chlorophyllides can be found in photosynthetic organisms. Generally, chlorophyllides have a-, b-, c-, d-, and f-type derivatives, and all chlorophyllides have a tetrapyrrole structure with a Mg ion at the center and a fifth isocyclic pentanone. Chlorophyllide a can be synthesized from protochlorophyllide a, divinyl chlorophyllide a, or chlorophyll. In addition, chlorophyllide a can be transformed into chlorophyllide b, chlorophyllide d, or chlorophyllide f. Chlorophyllide c can be synthesized from protochlorophyllide a or divinyl protochlorophyllide a. Chlorophyllides have been extensively used in food, medicine, and pharmaceutical applications. Furthermore, chlorophyllides exhibit many biological activities, such as anti-growth, antimicrobial, antiviral, antipathogenic, and antiproliferative activity. The photosensitivity of chlorophyllides that is applied in mercury electrodes and sensors were discussed. This article is the first detailed review dedicated specifically to chlorophyllides. Thus, this review aims to describe the definition of chlorophyllides, biosynthetic routes of chlorophyllides, purification of chlorophyllides, and applications of chlorophyllides.
Asunto(s)
Técnicas Biosensibles/métodos , Química Farmacéutica/métodos , Clorofila/análogos & derivados , Clorofilidas/síntesis química , Aditivos Alimentarios/química , Protoclorofilida/metabolismo , Antiinfecciosos/síntesis química , Antiinfecciosos/farmacología , Antineoplásicos Fitogénicos/biosíntesis , Antineoplásicos Fitogénicos/síntesis química , Antineoplásicos Fitogénicos/farmacología , Antivirales/síntesis química , Antivirales/farmacología , Técnicas Biosensibles/instrumentación , Clorofila/biosíntesis , Clorofila/farmacología , Clorofilidas/biosíntesis , Clorofilidas/farmacología , Técnicas Electroquímicas , Aditivos Alimentarios/metabolismo , Humanos , Luz , Estructura Molecular , Fotosíntesis/fisiología , Plantas/química , Plantas/metabolismoRESUMEN
Leaf is the major photosynthesis organ and the key source of wheat (Triticum aestivum L.) grain. Spotted leaf (spl) mutant is a kind of leaf lesion mimic mutants (LMMs) in plants, which is an ideal material for studying the mechanisms of leaf development. In this study, we report the leaf abnormal development molecular mechanism of a spl mutant named white stripe leaf (wsl) derived from wheat cultivar Guomai 301 (WT). Histochemical observation indicated that the leaf mesophyll cells of the wsl were destroyed in the necrosis regions. To explore the molecular regulatory network of the leaf development in mutant wsl, we employed transcriptome analysis, histochemistry, quantitative real-time PCR (qRT-PCR), and observations of the key metabolites and photosynthesis parameters. Compared to WT, the expressions of the chlorophyll synthesis and photosynthesis-related homeotic genes were repressed; many genes in the WRKY transcription factor (TF) families were highly expressed; the salicylic acid (SA) and Ca2+ signal transductions were enhanced in wsl. Both the chlorophyll contents and the photosynthesis rate were lower in wsl. The contents of SA and reactive oxygen species (ROS) were significantly higher, and the leaf rust resistance was enhanced in wsl. Based on the experimental data, a primary molecular regulatory model for leaf development in wsl was established. The results indicated that the SA accumulation and enhanced Ca2+ signaling led to programmed cell death (PCD), and ultimately resulted in spontaneous leaf necrosis of wsl. These results laid a solid foundation for further research on the molecular mechanism of leaf development in wheat.
Asunto(s)
Apoptosis/genética , Calcio/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Ácido Salicílico/metabolismo , Triticum/genética , Apoptosis/fisiología , Clorofila/biosíntesis , Perfilación de la Expresión Génica , Proteínas Nucleares/genética , Fotosíntesis/genética , Fotosíntesis/fisiología , Enfermedades de las Plantas/genética , Hojas de la Planta/genética , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/genética , Factores de Transcripción/metabolismo , Transcriptoma/genéticaRESUMEN
KEY MESSAGE: Using bulked segregant analysis combined with next-generation sequencing, we delimited the pv-ye gene responsible for the golden pod trait of snap bean cultivar A18-1. Sequence analysis identified Phvul.002G006200 as the candidate gene. The pod is the main edible part of snap beans (Phaseolus vulgaris L.). The commercial use of the pods is mainly affected by their color. Consumers seem to prefer golden pods. The aim of the present study was to identify the gene responsible for the golden pod trait in the snap bean. 'A18-1' (a golden bean cultivar) and 'Renaya' (a green bean cultivar) were chosen as the experimental materials. Genetic analysis indicated that a single recessive gene, pv-ye, controls the golden pod trait. A candidate region of 4.24 Mb was mapped to chromosome Pv 02 using bulked-segregant analysis coupled with whole-genome sequencing. In this region, linkage analysis in an F2 population localized the pv-ye gene to an interval of 182.9 kb between the simple sequence repeat markers SSR77 and SSR93. This region comprised 16 genes (12 annotated genes from the P. vulgaris database and 4 functionally unknown genes). Combined with transcriptome sequencing results, we identified Phvul.002G006200 as the potential candidate gene for pv-ye. Sequencing of Phvul.002G006200 identified a single-nucleotide polymorphism (SNP) in pv-ye. A pair of primers covering the SNP were designed, and the fragment was sequenced to screen 1086 F2 plants with the 'A18-1' phenotype. Our findings showed that among the 1086 mapped individuals, the SNP cosegregated with the 'A18-1' phenotype. The findings presented here could form the basis to reveal the molecular mechanism of the golden pod trait in the snap bean.
Asunto(s)
Genes de Plantas , Genes Recesivos , Phaseolus/genética , Pigmentación/genética , Secuencia de Bases , Carotenoides , Clorofila/biosíntesis , Mapeo Cromosómico , Color , Ligamiento Genético , Marcadores Genéticos , Repeticiones de Microsatélite , FenotipoRESUMEN
Chattonella species, C. marina and C. ovata, are harmful raphidophycean flagellates known to have hemolytic effects on many marine organisms and resulting in massive ecological damage worldwide. However, knowledge of the toxigenic mechanism of these ichthyotoxic flagellates is still limited. Light was reported to be responsible for the hemolytic activity (HA) of Chattonella species. Therefore, the response of photoprotective, photosynthetic accessory pigments, the photosystem II (PSII) electron transport chain, as well as HA were investigated in non-axenic C. marina and C. ovata cultures under variable environmental conditions (light, iron and addition of photosynthetic inhibitors). HA and hydrogen peroxide (H2O2) were quantified using erythrocytes and pHPA assay. Results confirmed that% HA of Chattonella was initiated by light, but was not always elicited during cell division. Exponential growth of C. marina and C. ovata under the light over 100 µmol m-2 s-1 or iron-sufficient conditions elicited high hemolytic activity. Inhibitors of PSII reduced the HA of C. marina, but had no effect on C. ovata. The toxicological response indicated that HA in Chattonella was not associated with the photoprotective system, i.e., xanthophyll cycle and regulation of reactive oxygen species, nor the PSII electron transport chain, but most likely occurred during energy transport through the light-harvesting antenna pigments. A positive, highly significant relationship between HA and chlorophyll (chl) biosynthesis pigments, especially chl c2 and chl a, in both species, indicated that hemolytic toxin may be generated during electron/energy transfer through the chl c2 biosynthesis pathway.
Asunto(s)
Hemolíticos/metabolismo , Toxinas Marinas/metabolismo , Fotosíntesis/fisiología , Estramenopilos/metabolismo , Biomarcadores/metabolismo , Clorofila/biosíntesis , Clorofila/metabolismo , Proteínas del Complejo de Cadena de Transporte de Electrón/metabolismo , Peróxido de Hidrógeno/metabolismo , Toxinas Marinas/biosíntesis , Complejo de Proteína del Fotosistema II/metabolismo , Estramenopilos/patogenicidadRESUMEN
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.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Proteínas del Choque Térmico HSP40/metabolismo , Proteínas de la Membrana/metabolismo , Morfogénesis/fisiología , Proteínas Quinasas/metabolismo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Brasinoesteroides/metabolismo , Clorofila/biosíntesis , Cloroplastos/metabolismo , Etiolado/fisiología , Regulación de la Expresión Génica de las Plantas/fisiología , Técnicas de Silenciamiento del Gen , Proteínas del Choque Térmico HSP40/genética , Proteínas del Choque Térmico HSP40/aislamiento & purificación , Luz , Proteínas de la Membrana/genética , Proteínas de la Membrana/aislamiento & purificación , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Morfogénesis/efectos de la radiación , Mutación , Plantas Modificadas Genéticamente , Proteínas Quinasas/genética , RNA-Seq , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Plantones/crecimiento & desarrollo , Transducción de Señal/fisiologíaRESUMEN
Citric acid (CA), as an organic chelator, plays a vital role in alleviating copper (Cu) stress-mediated oxidative damage, wherein a number of molecular mechanisms alter in plants. However, it remains largely unknown how CA regulates differentially abundant proteins (DAPs) in response to Cu stress in Brassica napus L. In the present study, we aimed to investigate the proteome changes in the leaves of B. L. seedlings in response to CA-mediated alleviation of Cu stress. Exposure of 21-day-old seedlings to Cu (25 and 50 µM) and CA (1.0 mM) for 7 days exhibited a dramatic inhibition of overall growth and considerable increase in the enzymatic activities (POD, SOD, CAT). Using a label-free proteome approach, a total of 6345 proteins were identified in differentially treated leaves, from which 426 proteins were differentially expressed among the treatment groups. Gene ontology (GO) and KEGG pathways analysis revealed that most of the differential abundance proteins were found to be involved in energy and carbohydrate metabolism, photosynthesis, protein metabolism, stress and defense, metal detoxification, and cell wall reorganization. Our results suggest that the downregulation of chlorophyll biosynthetic proteins involved in photosynthesis were consistent with reduced chlorophyll content. The increased abundance of proteins involved in stress and defense indicates that these DAPs might provide significant insights into the adaptation of Brassica seedlings to Cu stress. The abundances of key proteins were further verified by monitoring the mRNA expression level of the respective transcripts. Taken together, these findings provide a potential molecular mechanism towards Cu stress tolerance and open a new route in accelerating the phytoextraction of Cu through exogenous application of CA in B. napus.
Asunto(s)
Brassica napus/efectos de los fármacos , Ácido Cítrico/farmacología , Cobre/toxicidad , Contaminantes Ambientales/toxicidad , Proteínas de Plantas/genética , Proteoma/genética , Adaptación Fisiológica , Brassica napus/genética , Brassica napus/crecimiento & desarrollo , Brassica napus/metabolismo , Catalasa/genética , Catalasa/metabolismo , Clorofila/biosíntesis , Ácido Cítrico/metabolismo , Cobre/metabolismo , Contaminantes Ambientales/antagonistas & inhibidores , Contaminantes Ambientales/metabolismo , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Ontología de Genes , Redes y Vías Metabólicas/efectos de los fármacos , Redes y Vías Metabólicas/genética , Anotación de Secuencia Molecular , Peroxidasas/clasificación , Peroxidasas/genética , Peroxidasas/metabolismo , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Proteínas de Plantas/clasificación , Proteínas de Plantas/metabolismo , Proteoma/clasificación , Proteoma/metabolismo , Plantones/efectos de los fármacos , Plantones/genética , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Estrés Fisiológico , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismoRESUMEN
Chrysanthemum is one of the most beautiful and popular flowers in the world, and the flower color is an important ornamental trait of chrysanthemum. Compared with other flower colors, green flowers are relatively rare. The formation of green flower color is attributed to the accumulation of chlorophyll; however, the regulatory mechanism of chlorophyll metabolism in chrysanthemum with green flowers remains largely unknown. In this study, we performed Illumina RNA sequencing on three chrysanthemum materials, Chrysanthemum vestitum and Chrysanthemum morifolium cultivars 'Chunxiao' and 'Green anna', which produce white, light green and dark green flowers, respectively. Based on the results of comparative transcriptome analysis, a gene encoding a novel NAC family transcription factor, CmNAC73, was found to be highly correlated to chlorophyll accumulation in the outer whorl of ray florets in chrysanthemum. The results of transient overexpression in chrysanthemum leaves showed that CmNAC73 acts as a positive regulator of chlorophyll biosynthesis. Furthermore, transactivation and yeast one-hybrid assays indicated that CmNAC73 directly binds to the promoters of chlorophyll synthesis-related genes HEMA1 and CRD1. Thus, this study uncovers the transcriptional regulation of chlorophyll synthesis-related genes HEMA1 and CRD1 by CmNAC73 and provides new insights into the development of green flower color in chrysanthemum and chlorophyll metabolism in plants.
Asunto(s)
Clorofila/biosíntesis , Chrysanthemum/genética , Proteínas de Plantas/metabolismo , Factores de Transcripción/metabolismo , Clorofila/genética , Chrysanthemum/metabolismo , Flores/genética , Flores/metabolismo , Proteínas de Plantas/genética , Factores de Transcripción/genética , TranscriptomaRESUMEN
Biosyntheses of chlorophyll and heme in oxygenic phototrophs share a common trunk pathway that diverges with insertion of magnesium or iron into the last common intermediate, protoporphyrin IX. Since both tetrapyrroles are pro-oxidants, it is essential that their metabolism is tightly regulated. Here, we establish that heme-derived linear tetrapyrroles (bilins) function to stimulate the enzymatic activity of magnesium chelatase (MgCh) via their interaction with GENOMES UNCOUPLED 4 (GUN4) in the model green alga Chlamydomonas reinhardtii A key tetrapyrrole-binding component of MgCh found in all oxygenic photosynthetic species, CrGUN4, also stabilizes the bilin-dependent accumulation of protoporphyrin IX-binding CrCHLH1 subunit of MgCh in light-grown C. reinhardtii cells by preventing its photooxidative inactivation. Exogenous application of biliverdin IXα reverses the loss of CrCHLH1 in the bilin-deficient heme oxygenase (hmox1) mutant, but not in the gun4 mutant. We propose that these dual regulatory roles of GUN4:bilin complexes are responsible for the retention of bilin biosynthesis in all photosynthetic eukaryotes, which sustains chlorophyll biosynthesis in an illuminated oxic environment.
Asunto(s)
Pigmentos Biliares/fisiología , Chlamydomonas reinhardtii/metabolismo , Clorofila/biosíntesis , Péptidos y Proteínas de Señalización Intracelular/fisiología , Cianobacterias/metabolismo , Hemo Oxigenasa (Desciclizante) , Péptidos y Proteínas de Señalización Intracelular/química , Liasas/metabolismo , Protoporfirinas/químicaRESUMEN
In the chlorophyll biosynthesis pathway, the 8-vinyl group of the chlorophyll precursor is reduced to an ethyl group by 8-vinyl reductase. Two isozymes of 8-vinyl reductase have been described in oxygenic photosynthetic organisms: one encoded by BciA and another by BciB. Only BciB contains an [Fe-S] cluster and most cyanobacteria harbor this form; whereas a few contain BciA. Given this disparity in distribution, cyanobacterial BciA has remained largely overlooked, which has limited understanding of chlorophyll biosynthesis in these microorganisms. Here, we reveal that cyanobacterial BciA encodes a functional 8-vinyl reductase, as evidenced by measuring the in vitro activity of recombinant Synechococcus and Acaryochloris BciA. Genomic comparison revealed that BciB had been replaced by BciA during evolution of the marine cyanobacterium Synechococcus, and coincided with replacement of Fe-superoxide dismutase (SOD) with Ni-SOD. These findings imply that the acquisition of BciA confers an adaptive advantage to cyanobacteria living in low-iron oceanic environments.
Asunto(s)
Oxidorreductasas , Synechococcus , Organismos Acuáticos/enzimología , Organismos Acuáticos/genética , Clorofila/biosíntesis , Oxidorreductasas/genética , Oxidorreductasas/metabolismo , Fotosíntesis , Synechococcus/enzimología , Synechococcus/genéticaRESUMEN
Ferredoxins are single-electron carrier proteins involved in various cellular reactions. In chloroplasts, the most abundant ferredoxin accepts electrons from photosystem I and shuttles electrons via ferredoxin NADP+ oxidoreductase to generate NADPH or directly to ferredoxin dependent enzymes. In addition, plants contain other isoforms of ferredoxins. Two of these, named FdC1 and FdC2 in Arabidopsis thaliana, have C-terminal extensions and functions that are poorly understood. Here we identified disruption of the orthologous FdC2 gene in barley (Hordeum vulgare L.) mutants at the Viridis-k locus; these mutants are deficient in the aerobic cyclase reaction of chlorophyll biosynthesis. The magnesium-protoporphyrin IX monomethyl ester cyclase is one of the least characterized enzymes of the chlorophyll biosynthetic pathway and its electron donor has long been sought. Agroinfiltrations showed that the viridis-k phenotype could be complemented in vivo by Viridis-k but not by canonical ferredoxin. VirK could drive the cyclase reaction in vitro and analysis of cyclase mutants showed that in vivo accumulation of VirK is dependent on cyclase enzyme levels. The chlorophyll deficient phenotype of viridis-k mutants suggests that VirK plays an essential role in chlorophyll biosynthesis that cannot be replaced by other ferredoxins, thus assigning a specific function to this isoform of C-type ferredoxins.
Asunto(s)
Clorofila/biosíntesis , Ferredoxinas/genética , Ferredoxinas/metabolismo , Hordeum/metabolismo , Mapeo Cromosómico , Cromosomas de las Plantas , Electrones , Evolución Molecular , Ferredoxinas/química , Prueba de Complementación Genética , Hordeum/genética , Mutación , FilogeniaRESUMEN
The flesh of the taproot of Raphanus sativus L. is rich in chlorophyll (Chl) throughout the developmental process, which is why the flesh is green. However, little is known about which genes are associated with Chl accumulation in this non-foliar, internal green tissue and whether the green flesh can perform photosynthesis. To determine these aspects, we measured the Chl content, examined Chl fluorescence, and carried out comparative transcriptome analyses of taproot flesh between green-fleshed "Cuishuai" and white-fleshed "Zhedachang" across five developmental stages. Numerous genes involved in the Chl metabolic pathway were identified. It was found that Chl accumulation in radish green flesh may be due to the low expression of Chl degradation genes and high expression of Chl biosynthesis genes, especially those associated with Part â £ (from Protoporphyrin â ¨ to Chl a). Bioinformatics analysis revealed that differentially expressed genes between "Cuishuai" and "Zhedachang" were significantly enriched in photosynthesis-related pathways, such as photosynthesis, antenna proteins, porphyrin and Chl metabolism, carbon fixation, and photorespiration. Twenty-five genes involved in the Calvin cycle were highly expressed in "Cuishuai". These findings suggested that photosynthesis occurred in the radish green flesh, which was also supported by the results of Chl fluorescence. Our study provides transcriptome data on radish taproots and provides new information on the formation and function of radish green flesh.