RESUMO
Maize (Zea mays L.) is an important food crop with a wide range of uses in both industry and agriculture. Drought stress during its growth cycle can greatly reduce maize crop yield and quality. However, the molecular mechanisms underlying maize responses to drought stress remain unclear. In this work, a WRKY transcription factor-encoding gene, ZmWRKY30, from drought-treated maize leaves was screened out and characterized. ZmWRKY30 gene expression was induced by dehydration treatments. The ZmWRKY30 protein localized to the nucleus and displayed transactivation activity in yeast. Compared with wild-type (WT) plants, Arabidopsis lines overexpressing ZmWRKY30 exhibited a significantly enhanced drought stress tolerance, as evidenced by the improved survival rate, increased antioxidant enzyme activity by superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), elevated proline content, and reduced lipid peroxidation recorded after drought stress treatment. In contrast, the mutator (Mu)-interrupted ZmWRKY30 homozygous mutant (zmwrky30) was more sensitive to drought stress than its null segregant (NS), characterized by the decreased survival rate, reduced antioxidant enzyme activity (SOD, POD, and CAT) and proline content, as well as increased malondialdehyde accumulation. RNA-Seq analysis further revealed that, under drought conditions, the knockout of the ZmWRKY30 gene in maize affected the expression of genes involved in reactive oxygen species (ROS), proline, and myo-inositol metabolism. Meanwhile, the zmwrky30 mutant exhibited significant downregulation of myo-inositol content in leaves under drought stress. Combined, our results suggest that ZmWRKY30 positively regulates maize responses to water scarcity. This work provides potential target genes for the breeding of drought-tolerant maize.
Assuntos
Resistência à Seca , Inositol , Proteínas de Plantas , Espécies Reativas de Oxigênio , Zea mays , Antioxidantes/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Homeostase , Inositol/metabolismo , Folhas de Planta/genética , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Zea mays/genética , Zea mays/fisiologiaRESUMO
KEY MESSAGE: ZmWRKY64 positively regulates Arabidopsis and maize Cd stress through modulating Cd uptake, translocation, and ROS scavenging genes expression. Cadmium (Cd) is a highly toxic heavy metal with severe impacts on crops growth and development. The WRKY transcription factor is a significant regulator influencing plant stress response. Nevertheless, the function of the WRKY protein in maize Cd stress response remains unclear. Here, we identified a maize WRKY gene, ZmWRKY64, the expression of which was enhanced in maize roots and leaves under Cd stress. ZmWRKY64 was localized in the nucleus and displayed transcriptional activity in yeast. Heterologous expression of ZmWRKY64 in Arabidopsis diminished Cd accumulation in plants by negatively regulating the expression of AtIRT1, AtZIP1, AtHMA2, AtNRAMP3, and AtNRAMP4, which are involved in Cd uptake and transport, resulting in Cd stress tolerance. Knockdown of ZmWRKY64 in maize led to excessive Cd accumulation in leaf cells and in the cytosol of the root cells, resulting in a Cd hypersensitive phenotype. Further analysis confirmed that ZmWRKY64 positively regulated ZmABCC4, ZmHMA3, ZmNRAMP5, ZmPIN2, ZmABCG51, ZmABCB13/32, and ZmABCB10, which may influence Cd translocation and auxin transport, thus mitigating Cd toxicity in maize. Moreover, ZmWRKY64 could directly enhance the transcription of ZmSRG7, a reported key gene regulating reactive oxygen species homeostasis under abiotic stress. Our results indicate that ZmWRKY64 is important in maize Cd stress response. This work provides new insights into the WRKY transcription factor regulatory mechanism under a Cd-polluted environment and may lead to the genetic improvement of Cd tolerance in maize.
Assuntos
Arabidopsis , Fatores de Transcrição , Fatores de Transcrição/genética , Cádmio/toxicidade , Zea mays/genética , Arabidopsis/genética , Regulação da Expressão GênicaRESUMO
Maize is an important food and cash crop worldwide. The WUSCHEL (WUS)-related homeobox (WOX) transcription factor (TF) family plays a significant role in the development process and the response to abiotic stress of plants. However, few studies have been reported on the function of WOX genes in maize. This work, utilizing the latest maize B73 reference genome, results in the identification of 22 putative ZmWOX gene family members. Except for chromosome 5, the 22 ZmWOX genes were homogeneously distributed on the other nine chromosomes and showed three tandem duplication and 10 segmental duplication events. Based on phylogenetic characteristics, ZmWOXs are divided into three clades (e.g., WUS, intermediate, and ancient groups), and the majority of ZmWOXs in same group display similar gene and protein structures. Cross-species collinearity results indicated that some WOX genes might be evolutionarily conservative. The promoter region of ZmWOX family members is enriched in light, plant growth/hormone, and abiotic stress-responsive elements. Tissue-specific expression evaluation showed that ZmWOX genes might play a significant role in the occurrence of maize reproductive organs. Transcriptome data and RT-qPCR analysis further showed that six ZmWOX genes (e.g., ZmWOX1, 4, 6, 13, 16, and 18) were positively or negatively modulated by temperature, salt, and waterlogging stresses. Moreover, two ZmWOXs, ZmWOX1 and ZmWOX18, both were upregulated by abiotic stress. ZmWOX18 was localized in the nucleus and had transactivation activities, while ZmWOX1 was localized in both the cytoplasm and nucleus, without transactivation activity. Overall, this work offers new perspectives on the evolutionary relationships of ZmWOX genes and might provide a resource for further detecting the biological functions of ZmWOXs.
Assuntos
Genes Homeobox , Zea mays , Zea mays/genética , Filogenia , Fatores de Transcrição/genética , Estresse Fisiológico/genéticaRESUMO
Cadmium (Cd) is a toxic heavy metal that seriously affects metabolism after accumulation in plants, and it also causes adverse effects on humans through the food chain. The HIPP gene family has been shown to be highly tolerant to Cd stress due to its special domain and molecular structure. This study described the Cd-induced gene ApHIPP26 from the hyperaccumulator Arabis paniculata. Its subcellular localization showed that ApHIPP26 was located in the nucleus. Transgenic Arabidopsis overexpressing ApHIPP26 exhibited a significant increase in main root length and fresh weight under Cd stress. Compared with wild-type lines, Cd accumulated much more in transgenic Arabidopsis both aboveground and underground. Under Cd stress, the expression of genes related to the absorption and transport of heavy metals underwent different changes in parallel, which were involved in the accumulation and distribution of Cd in plants, such as AtNRAMP6 and AtNRAMP3. Under Cd stress, the activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) in the transgenic lines were higher than those in the wild type. The physiological and biochemical indices showed that the proline and chlorophyll contents in the transgenic lines increased significantly after Cd treatment, while the malondialdehyde (MDA) content decreased. In addition, the gene expression profile analysis showed that ApHIPP26 improved the tolerance of Arabidopsis to Cd by regulating the changes of related genes in plant hormone signal transduction pathway. In conclusion, ApHIPP26 plays an important role in cadmium tolerance by alleviating oxidative stress and regulating plant hormones, which provides a basis for understanding the molecular mechanism of cadmium tolerance in plants and provides new insights for phytoremediation in Cd-contaminated areas.
Assuntos
Arabidopsis , Arabis , Metais Pesados , Humanos , Cádmio/toxicidade , Cádmio/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Metais Pesados/metabolismo , Antioxidantes/metabolismoRESUMO
Cadmium (Cd) is a highly toxic pollutant in soil and water that severely hampers the growth and reproduction of plants. Phytoremediation has been presented as a cost-effective and eco-friendly method for addressing heavy metal pollution. However, phytoremediation is restricted by the limited number of accumulators and the unknown mechanisms underlying heavy metal tolerance. In this study, we demonstrated that Erigeron canadensis (Asteraceae), with its strong adaptability, is tolerant to intense Cd stress (2 mmol/L CdCl2 solution). Moreover, E. canadensis exhibited a strong ability to accumulate Cd2+ when treated with CdCl2 solution. The activity of some antioxidant enzymes, as well as the malondialdehyde (MDA) level, was significantly increased when E. canadensis was treated with different CdCl2 solutions (0.5, 1, 2 mmol/L CdCl2). We found high levels of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities under 1 mmol/L CdCl2 treatment. Comparative transcriptomic analysis identified 5,284 differentially expressed genes (DEGs) in the roots and 3,815 DEGs in the shoots after E. canadensis plants were exposed to 0.5 mM Cd. Functional annotation of key DEGs indicated that signal transduction, hormone response, and reactive oxygen species (ROS) metabolism responded significantly to Cd. In particular, the DEGs involved in auxin (IAA) and ethylene (ETH) signal transduction were overrepresented in shoots, indicating that these genes are mainly involved in regulating plant growth and thus likely responsible for the Cd tolerance. Overall, these results not only determined that E. canadensis can be used as a potential accumulator of Cd but also provided some clues regarding the mechanisms underlying heavy metal tolerance.
Assuntos
Asteraceae , Erigeron , Cádmio/toxicidade , Perfilação da Expressão Gênica , Transcriptoma , AntioxidantesRESUMO
Submergence stress represents a serious threat to the yield and quality of maize because it can lead to oxygen deficiency and the accumulation of toxic metabolites. However, the mechanisms by which maize resists the adverse effects of submergence stress have yet to be fully elucidated. Here, we cloned a gene from maize Balem (Barley aleurone and embryo), ZmB12D, which was expressed at significant levels in seed embryos during imbibition and in leaves under submergence stress. Subcellular localization analysis indicated that the ZmB12D protein was localized in the mitochondria. The overexpression of ZmB12D in increased the tolerance of Arabidopsis to submergence stress, probably due to a reduction in the levels of malonaldehyde (MDA), the increased activity of antioxidant enzymes (SOD, POD and CAT), enhanced electron transport by coordinating the expression of non-symbiotic hemoglobin-2 (AHb2) and Fe transport-related (AtNAS3) genes (mediating Fe and oxygen availability) and also modulated the anaerobic respiration rates through upregulated the AtPDC1, AtADH1, AtSUS4 genes under submergence. Yeast one-hybrid (Y1H) and transient transactivation assays demonstrated that ZmWRKY70 bound to the ZmB12D promoter and activated ZmB12D. Collectively, out findings indicate that ZmB12D plays an important role in the tolerance of maize to submergence stress. This research provides new insights into the genetic improvement of maize with regards to submergence tolerance.
Assuntos
Arabidopsis , Arabidopsis/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas , Oxigênio/metabolismo , Estresse Fisiológico/genética , Plantas Geneticamente Modificadas/genéticaRESUMO
Cadmium (Cd), which is a nonessential heavy metal element for organisms, can have a severe impact on the growth and development of organisms that absorb excessive Cd. Studies have shown that Brassica carinata, a semiwild oil crop, has strong tolerance to various abiotic stresses, and RNA-seq has revealed that the B. carinata superoxide dismutase gene (BcaSOD1) likely responds to Cd stress. To elucidate the BcaSOD1 function involved in tolerance of Cd stress, we cloned the coding sequences of BcaSOD1 from a purple B. carinata accession and successfully transferred it into Arabidopsis thaliana. The subcellular localization results demonstrated that BcaSOD1 was primarily located in the plasma membrane, mitochondria and nucleus. Overexpression of BcaSOD1 in transgenic Arabidopsis (OE) effectively decreased the toxicity caused by Cd stress. Compared to the WT (wild type lines), the OE lines exhibited significantly increased activities of antioxidant enzymes (APX, CAT, POD, and SOD) after exposure to 2.5 mM CdCl2. The Cd content of underground (root) in the OE line was dominantly higher than that in the WT; however, the Cd content of aboveground (shoot) was comparable between the OE and WT types. Moreover, the qRTâPCR results showed that several heavy metal detoxification-related genes (AtIREG2, AtMTP3, AtHMA3, and AtNAS4) were significantly upregulated in the roots of OE lines under Cd treatment, suggesting that these genes are likely involved in Cd absorption in the roots of OE lines. In addition, both comparable transcriptome and qRT-PCR analyses revealed that exogenous BcaSOD1 noticeably facilitates detoxification by stimulating the expression of two arginine (Arg) biosynthesis genes (AtGDH1 and AtGDH2) while inhibiting the expression of AtARGAH1, a negative regulator in biosynthesis of Arg. The Arg content was subsequently confirmed to be significantly enhanced in OE lines under Cd treatment, indicating that BcaSOD1 likely strengthened Cd tolerance by regulating the expression of Arg-related genes. This study demonstrates that BcaSOD1 can enhance Cd tolerance and reveals the molecular mechanism of this gene, providing valuable insights into the molecular mechanism of Cd tolerance in plants.
Assuntos
Arabidopsis , Metais Pesados , Cádmio/toxicidade , Cádmio/metabolismo , Arabidopsis/metabolismo , Superóxido Dismutase/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Metais Pesados/toxicidade , Metais Pesados/metabolismo , Arginina/genética , Arginina/metabolismoRESUMO
Hypoxic stress due to submergence is a serious threat to the growth and development of maize. WRKY transcription factors are significant regulators of plant responses to various abiotic and biotic stresses. Nevertheless, their function and regulatory mechanisms in the resistance of maize to submergence stress remain unclear. Here we report the cloning of a maize WRKY transcription factor gene, ZmWRKY70, transcripts of which accumulate under submergence stress in maize seedlings. Subcellular localization analysis and yeast transcriptional activation assay indicated that ZmWRKY70 was localized in the nucleus and had transcriptional activation activity. Heterologous overexpression of ZmWRKY70 in Arabidopsis increased the tolerance of seeds and seedlings to submergence stress by upregulating the transcripts of several key genes involved in anaerobic respiration, such as group VII ethylene-responsive factor (ERFVII) (AtRAP2.2), alcohol dehydrogenase (AtADH1), pyruvate decarboxylase (AtPDC1/2), and sucrose synthase (AtSUS4), under submergence conditions. Moreover, the overexpression of ZmWRKY70 in maize mesophyll protoplasts enhanced the expression of ZmERFVII members (ZmERF148, ZmERF179, and ZmERF193), ZmADH1, ZmPDC2/3, and ZmSUS1. Yeast one-hybrid and dual-luciferase activity assays further confirmed that ZmWRKY70 enhanced the expression of ZmERF148 by binding to the W box motif located in the promoter region of ZmERF148. Together, these results indicate that ZmWRKY70 plays a significant role in tolerance of submergence stress. This work provides a theoretical basis, and suggests excellent genes, for biotechnological breeding to improve the tolerance of maize to submergence through the regulation of ZmWRKY genes.
Assuntos
Arabidopsis , Arabidopsis/metabolismo , Zea mays/metabolismo , Saccharomyces cerevisiae/metabolismo , Melhoramento Vegetal , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Estresse Fisiológico/genética , Plântula/metabolismo , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
Arabis paniculata is a newly discovered hyperaccumulator known for its ability to accumulate multiple metals. WRKY proteins play a significant role in plant responses to various stresses, including cadmium (Cd) stress. However, there is limited research on the molecular biology of Arabis paniculata, especially regarding the WRKY family. In this study, we conducted third-generation sequencing for functional annotation and structural analysis of Arabis paniculata. We obtained 41,196 high-quality isoforms from the full-length transcriptome, with an average length of 1043 bp. A total of 26,670 genes were predicted against NR, Swissprot, KOG, and KEGG databases. Functional comparison using the KOG database revealed excellent annotation in 25 functional categories, with general function prediction (1822 items) being the most predominant. MISA analysis identified 12,593 SSR loci, with single nucleotide repeats being the largest category (44.83% of the total). Moreover, our predictions provide insights into 20,022 coding sequences (CDS), 811 transcription factors, and 17,963 LncRNAs. In total, 34 WRKY gene sequences were identified in Arabis paniculata. Bioinformatics analysis revealed diverse numbers of amino acids in these WRKYs (113 to 545 aa), and a conserved WRKYGQK sequence within the N-terminus of the WRKY protein. Furthermore, all WRKYs were found to be localized in the nucleus. Phylogenetic analysis classified the WRKY genes into three categories: I (14 members), II (17 members), and III (3 members). Category II was subsequently divided into four sub-categories: II-a (8 members), II-b (1 member), II-c (1 member), and II-d (7 members). Our quantitative real-time polymerase chain reaction (qRT-PCR) experiments revealed that ApWRKY23 and ApWRKY34 exhibited the highest expression levels at the 24-h time point, suggesting their potential role as the candidate genes for Cd stress response. These findings contribute to our understanding of the genomic information of Arabis paniculata and provide a basis for the analysis of its genetic diversity. Additionally, this study paves the way for a comprehensive exploration of the molecular mechanisms underlying the WRKY genes in Arabis paniculata under Cd stress conditions.
RESUMO
Lonicera ruprechtiana Regel is widely used as a greening tree in China and also displays excellent pharmacological activities. The phylogenetic relationship between L. ruprechtiana and other members of Caprifoliaceae remains unclear. In this study, the complete cp genome of L. ruprechtiana was identified using high-throughput Illumina pair-end sequencing data. The circular cp genome was 154,611 bp long and has a large single-copy region of 88,182 bp and a small single-copy region of 18,713 bp, with the two parts separated by two inverted repeat (IR) regions (23,858 bp each). A total of 131 genes were annotated, including 8 ribosomal RNAs, 39 transfer RNAs, and 84 protein-coding genes (PCGs). In addition, 49 repeat sequences and 55 simple sequence repeat loci of 18 types were also detected. Codon usage analysis demonstrated that the Leu codon is preferential for the A/U ending. Maximum-likelihood phylogenetic analysis using 22 Caprifoliaceae species revealed that L. ruprechtiana was closely related to Lonicera insularis. Comparison of IR regions revealed that the cp genome of L. ruprechtiana was largely conserved with that of congeneric species. Moreover, synonymous (Ks) and non-synonymous (Ka) substitution rate analysis showed that most genes were under purifying selection pressure; ycf3, and some genes associated with subunits of NADH dehydrogenase, subunits of the cytochrome b/f complex, and subunits of the photosystem had been subjected to strong purifying selection pressure (Ka/Ks < 0.1). This study provides useful genetic information for future study of L. ruprechtiana evolution.
Assuntos
Caprifoliaceae/genética , Genoma de Cloroplastos/genética , Lonicera/genética , Sequência Conservada/genética , Genes de Plantas/genética , Repetições de Microssatélites/genética , Fotossíntese/genética , Filogenia , Análise de Sequência de DNARESUMO
The formal intramolecular photoredox reaction initially discovered for the parent 2-(hydroxymethyl)anthraquinone (1) has been extended to include analogs 3-6 in which the oxidizable benzyl alcohol group is significantly further away from the anthraquinone moiety. All of 3-6 undergo a clean and efficient formal intramolecular photoredox reaction in water catalyzed by acid (Phi = 0.1-0.6), in which the alcohol is oxidized to aldehyde and the anthraquinone is reduced to dihydroxyanthracene. The need for water, observation of acid catalysis, unimolecularity of reaction in anthraquinone, AM1 calculations and LFP studies support a mechanism involving a highly polarized triplet excited state in which the electron density of the distal phenyl moieties is transferred to the central anthraquinone ring, which is subsequently trapped adiabatically by protonation at the anthraquinone carbonyl oxygen and deprotonation at the benzyl C-H.
RESUMO
The formal intramolecular photoredox reaction initially discovered for the parent 2-(hydroxymethyl)anthraquinone (1) in aqueous solution has been extended to a variety of anthraquinones derivatives 6-13, to explore the generality of the reaction, and to investigate its potential utility as a photodeprotecting chromophore. In addition, the related diketone 14 was studied to investigate the need for the anthraquinone chromophore in these formal intramolecular reactions. All the anthraquinones studied (except for 9) undergo formal unimolecular photoredox reaction with a range of quantum yields (Phi = 0.02-0.7). Anthraquinones 7, 8, 10 and 11 photoreleased the corresponding alcohol, aldehyde, or ketone with good yields (80-90%), making it potentially useful for photocaging in aqueous solution. Diketone 14 undergoes an analogous photoredox reaction but only in acid (Phi = 0.003, pH < 1), to give the formal redox product diphenylisobenzofuran 32 thereby demonstrating that other aromatic diketones can react in an analogous fashion. The ionic photochemistry exhibited by these aromatic ketones is fully compatible with the recent discovery of the surprising acid-catalyzed photochemical hydration of benzophenone reported by Jacob Wirz and coworkers (M. Ramseier, P. Senn and J. Wirz, J. Phys. Chem. A, 2003, 107, 3305-3315).