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1.
Plant Mol Biol ; 103(3): 355-371, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32193789

RESUMO

KEYMESSAGE: Biphasic starch granules in maize ae mutant underwent the weak to strong SBEIIb-defective effect during endosperm development, leading to no birefringence in their exterior due to extended long branch-chains of amylopectin. Biphasic starch granules are usually detected regionally in cereal endosperm lacking starch branching enzyme (SBE). However, their molecular structure, formation mechanism, and regional distribution are unclear. In this research, biphasic starch granules were observed in the inner region of crown endosperm of maize ae mutant, and had poorly oriented structure with comb-like profiles in their exterior. The inner endosperm (IE) rich in biphasic starch granules and outer endosperm (OE) without biphasic starch granules were investigated. The starch had lower amylose content and higher proportion of long branch-chains of amylopectin in IE than in OE, and the exterior of biphasic starch granules had less amylose and more long branch-chains of amylopectin than the interior. Compared with OE, the expression pattern of starch synthesis related enzymes changed significantly in IE. The granule-bound starch synthase I activity within biphasic starch granules decreased slightly. The IE experienced more severe hypoxic stress than OE, and the up-regulated anaerobic respiration pathway indicated an increase in carbon consumption. The starch in IE underwent the SBEIIb-defective effect from weak to strong due to the lack of sufficient carbon inflow, leading to the formation of biphasic starch granules and their regional distribution in endosperm. The results provided information for understanding the biphasic starch granules.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Amido/metabolismo , Zea mays/enzimologia , Enzima Ramificadora de 1,4-alfa-Glucana/classificação , Enzima Ramificadora de 1,4-alfa-Glucana/genética , Endosperma/enzimologia , Endosperma/ultraestrutura , Amido/ultraestrutura
2.
Nat Commun ; 11(1): 988, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32080171

RESUMO

Increasing grain yield of maize (Zea mays L.) is required to meet the rapidly expanding demands for maize-derived food, feed, and fuel. Breeders have enhanced grain productivity of maize hybrids by pyramiding desirable characteristics for larger ears. However, loci selected for improving grain productivity remain largely unclear. Here, we show that a serine/threonine protein kinase encoding gene KERNEL NUMBER PER ROW6 (KNR6) determines pistillate floret number and ear length. Overexpression of KNR6 or introgression of alleles lacking the insertions of two transposable elements in the regulatory region of KNR6 can significantly enhance grain yield. Further in vitro evidences indicate that KNR6 can interact with an Arf GTPase-activating protein (AGAP) and its phosphorylation by KNR6 may affect ear length and kernel number. This finding provides knowledge basis to enhance maize hybrids grain yield.


Assuntos
Proteínas de Plantas/genética , Proteínas Serina-Treonina Quinases/genética , Zea mays/genética , Mapeamento Cromossômico , Grão Comestível/enzimologia , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Proteínas Ativadoras de GTPase/metabolismo , Genes de Plantas , Fenótipo , Fosforilação , Melhoramento Vegetal , Proteínas de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Locos de Características Quantitativas , Zea mays/enzimologia , Zea mays/crescimento & desenvolvimento
3.
Physiol Plant ; 168(1): 38-57, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30714160

RESUMO

In plants, CALCIUM-DEPENDENT PROTEIN KINASES (CDPKs/CPKs) are involved in calcium signaling in response to endogenous and environmental stimuli. Here, we report that ZmCPK11, one of maize CDPKs, participates in salt stress response and tolerance. Salt stress induced expression and upregulated the activity of ZmCPK11 in maize roots and leaves. Activation of ZmCPK11 upon salt stress was also observed in roots and leaves of transgenic Arabidopsis plants expressing ZmCPK11. The transgenic plants showed a long-root phenotype under control conditions and a short-root phenotype under NaCl, abscisic acid (ABA) or jasmonic acid (JA) treatment. Analysis of ABA and JA content in roots indicated that ZmCPK11 can mediate root growth by regulating the levels of these phytohormones. Moreover, 4-week-old transgenic plants were more tolerant to salinity than the wild-type plants. Their leaves were less chlorotic and showed weaker symptoms of senescence accompanied by higher chlorophyll content and higher quantum efficiency of photosystem II. The expression of Na+ /K+ transporters (HKT1, SOS1 and NHX1) and transcription factors (CBF1, CBF2, CBF3, ZAT6 and ZAT10) with known links to salinity tolerance was upregulated in roots of the transgenic plants upon salt stress. Furthermore, the transgenic plants accumulated less Na+ in roots and leaves under salinity, and showed a higher K+ /Na+ ratio in leaves. These results show that the improved salt tolerance in ZmCPK11-transgenic plants could be due to an upregulation of genes involved in the maintenance of intracellular Na+ and K+ homeostasis and a protection of photosystem II against damage.


Assuntos
Arabidopsis/fisiologia , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas Quinases/metabolismo , Tolerância ao Sal , Zea mays/enzimologia , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Homeostase , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas , Plantas Geneticamente Modificadas/fisiologia , Potássio/análise , Proteínas Quinases/genética , Sódio , Simportadores de Cloreto de Sódio-Potássio , Fatores de Transcrição , Zea mays/genética
4.
Environ Pollut ; 258: 113705, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31864075

RESUMO

Heavy metal accumulation in agricultural land causes crop production losses worldwide. Metal homeostasis within cells is tightly regulated. However, homeostasis breakdown leads to accumulation of reactive oxygen species (ROS). Overall plant fitness under stressful environment is determined by coordination between roots and shoots. But little is known about organ specific responses to heavy metals, whether it depends on the metal category (redox or non-redox reactive) and if these responses are associated with heavy metal accumulation in each organ or there are driven by other signals. Maize seedlings were subjected to sub-lethal concentrations of four metals (Zn, Ni, Cd and Cu) individually, and were quantified for growth, ABA level, and redox alterations in roots, mature leaves (L1,2) and young leaves (L3,4) at 14 and 21 days after sowing (DAS). The treatments caused significant increase in endogenous metal levels in all organs but to different degrees, where roots showed the highest levels. Biomass was significantly reduced under heavy metal stress. Although old leaves accumulated less heavy metal content than root, the reduction in their biomass (FW) was more pronounced. Metal exposure triggered ABA accumulation and stomatal closure mainly in older leaves, which consequently reduced photosynthesis. Heavy metals induced oxidative stress in the maize organs, but to different degrees. Tocopherols, polyphenols and flavonoids increased specifically in the shoot under Zn, Ni and Cu, while under Cd treatment they played a minor role. Under Cu and Cd stress, superoxide dismutase (SOD) and dehydroascorbate reductase (DHAR) activities were induced in the roots, however ascorbate peroxidase (APX) activity was only increased in the older leaves. Overall, it can be concluded that root and shoot organs specific responses to heavy metal toxicity are not only associated with heavy metal accumulation and they are specialized at the level of antioxidants to cope with.


Assuntos
Antioxidantes/metabolismo , Metais Pesados/toxicidade , Estresse Oxidativo , Zea mays/efeitos dos fármacos , Zea mays/enzimologia , Peróxido de Hidrogênio , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/enzimologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/enzimologia , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/enzimologia
5.
Phytochemistry ; 169: 112165, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31610323

RESUMO

Cyclin dependent kinase A; 1 (CDKA; 1) is essential in G1/S transition of cell cycle and its oxidation has been implicated in cell cycle arrest during plant abiotic stress. In the present study, an evaluation at the molecular level was performed to find possible sites of protein oxidative modifications. In vivo studies demonstrated that carbonylation of maize CDKA,1 is associated with a decrease in complex formation with maize cyclin D (CycD). Control and in vitro oxidized recombinant CDKA; 1 were sequenced by mass spectrometry. Proline at the PSTAIRE cyclin-binding motif was identified as the most susceptible oxidation site by comparative analysis of the resulted peptides. The specific interaction between CDKA; 1 and CycD6; 1, measured by surface plasmon resonance (SPR), demonstrated that the affinity and the kinetic of the interaction depended on the reduced-oxidized state of the CDKA; 1. CDKA; 1 protein oxidative modification would be in part responsible for affecting cell cycle progression, and thus producing plant growth inhibition under oxidative stress.


Assuntos
Quinases Ciclina-Dependentes/metabolismo , Ciclinas/metabolismo , Prolina/metabolismo , Zea mays/enzimologia , Sequência de Aminoácidos , Quinases Ciclina-Dependentes/química , Quinases Ciclina-Dependentes/genética , Ciclinas/química , Modelos Moleculares , Oxirredução , Prolina/química , Alinhamento de Sequência
6.
Int J Mol Sci ; 20(24)2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31817801

RESUMO

Calcium-dependent protein kinase (CPKs) is a key player in the calcium signaling pathway to decode calcium signals into various physiological responses. cDNA sequences of 9 ZmCPK genes were successfully cloned from all four phylogenetic groups in maize. qRT-PCR analysis showed the expression variation of these selected genes under abscisic acid (ABA) and calcium chloride (CaCl2) treatment. Due to the presence of N-myristoylation/palmitoylation sites, the selected ZmCPK members were localized in a plasma membrane. To clarify whether ZmCPK, a key player in calcium signaling, interacts with key players of ABA, protein phosphatase 2Cs (PP2Cs) and the SNF1-related protein kinase 2s (SnRK2s) and mitogen-activated protein kinase (MAPK) signaling pathways in maize, we examined the interaction between 9 CPKs, 8 PP2Cs, 5 SnRKs, and 20 members of the MPK family in maize by using yeast two-hybrid assay. Our results showed that three ZmCPKs interact with three different members of ZmSnRKs while four ZmCPK members had a positive interaction with 13 members of ZmMPKs in different combinations. These four ZmCPK proteins are from three different groups in maize. These findings of physical interactions between ZmCPKs, ZmSnRKs, and ZmMPKs suggested that these signaling pathways do not only have indirect influence but also have direct crosstalk that may involve the defense mechanism in maize. The present study may improve the understanding of signal transduction in plants.


Assuntos
Proteínas de Plantas/metabolismo , Proteínas Quinases/metabolismo , Zea mays/enzimologia , Zea mays/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Proteínas de Plantas/genética , Proteínas Quinases/genética , Transdução de Sinais/genética , Transdução de Sinais/fisiologia
7.
Proc Natl Acad Sci U S A ; 116(47): 23850-23858, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31685622

RESUMO

Increasing maize grain yield has been a major focus of both plant breeding and genetic engineering to meet the global demand for food, feed, and industrial uses. We report that increasing and extending expression of a maize MADS-box transcription factor gene, zmm28, under the control of a moderate-constitutive maize promoter, results in maize plants with increased plant growth, photosynthesis capacity, and nitrogen utilization. Molecular and biochemical characterization of zmm28 transgenic plants demonstrated that their enhanced agronomic traits are associated with elevated plant carbon assimilation, nitrogen utilization, and plant growth. Overall, these positive attributes are associated with a significant increase in grain yield relative to wild-type controls that is consistent across years, environments, and elite germplasm backgrounds.


Assuntos
Produtos Agrícolas/genética , Grão Comestível , Genes de Plantas , Zea mays/genética , Sequência de Aminoácidos , Produtos Agrícolas/enzimologia , Glutamato-Amônia Ligase/metabolismo , Nitrato Redutase/metabolismo , Nitrogênio/metabolismo , Fotossíntese/genética , Folhas de Planta/fisiologia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Ligação Proteica , Transcriptoma , Zea mays/enzimologia
8.
Plant Sci ; 289: 110243, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31623796

RESUMO

Maize (Zea mays) seeds are the major source of starch all over the world and the excellent model for researching starch synthesis. Seed starch content is a typical quantitative phenotype and many reports revealed that the glycolytic enzymes are involved in regulating starch synthesis, however the regulatory mechanism is still unclear. Here, we present a comparative phosphoproteomic study of three maize inbred lines with different seed starch content. It reveals that abundances of 62 proteins and 63 phosphoproteins were regulated during maize seed development. Dynamics of 17 enzymes related to glycolysis and starch synthesis were used to construct a phosphorylation regulatory network of starch synthesis. It shows that starch synthesis and glycolysis in maize seeds utilize the same hexose phosphates pool coming from sorbitol and sucrose as carbon source, and phosphorylation of ZmENO1 are suggested to contribute to increase starch content, because it is positively related to seed starch content in different developmental stages and different lines, and the phosphor-mimic mutant (ZmENO1S43D) damaged its enzyme activity which is vital in glycolysis. Our results provide a new sight into regulatory process of seed starch synthesis and can be used in maize breeding for high starch content.


Assuntos
Regulação da Expressão Gênica de Plantas , Fosfoproteínas/genética , Fosfopiruvato Hidratase/genética , Proteínas de Plantas/genética , Proteoma/genética , Amido/metabolismo , Zea mays/metabolismo , Fosfoproteínas/metabolismo , Fosfopiruvato Hidratase/metabolismo , Proteínas de Plantas/metabolismo , Proteoma/metabolismo , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Zea mays/enzimologia , Zea mays/genética , Zea mays/crescimento & desenvolvimento
9.
J Agric Food Chem ; 67(42): 11568-11576, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31584809

RESUMO

Tribenuron-methyl (TM), as one of the sulfonylurea (SU) herbicides, has been widely and effectively applied for many kinds of plants. SUs inhibit plant growth by restraining the biosynthetic pathway of branched-chain amino acids (BCAAs) catalyzed by acetolactate synthase (ALS). Safeners are agrochemicals that protect crops from herbicide injuries. To improve the crop tolerance under TM toxicity stress, this paper evaluated the protective effect of N-tosyloxazolidine-3-carboxamide. It turned out that most of the tested compounds showed significant protection against TM via enhancing the glutathione (GSH) content and glutathione S-transferase (GST) activity. Among all of the tested compounds, compound 16 exhibited more excellent protection than the contrast safener R-28725 and other target compounds. A positive correlation between the growth level, endogenous GSH content, and GST activity was observed in this research. The GST kinetic parameter Vmax of the maize was increased by 29.6% after treatment with compound 16, while Km was decreased by 51.9% compared to the untreated control. The molecular docking model indicated that compound 16 could compete with TM in the active site of ALS, which could interpret the protective effects of safeners. The present work demonstrated that N-tosyloxazolidine-3-carboxamide derivatives could be considered as potential candidates for developing new safeners in the future.


Assuntos
Herbicidas/toxicidade , Proteínas de Plantas/metabolismo , Substâncias Protetoras/farmacologia , Zea mays/efeitos dos fármacos , Zea mays/enzimologia , Acetolactato Sintase/química , Acetolactato Sintase/metabolismo , Glutationa Transferase/química , Glutationa Transferase/metabolismo , Cinética , Simulação de Acoplamento Molecular , Proteínas de Plantas/química , Compostos de Sulfonilureia/toxicidade , Zea mays/química
10.
Int J Mol Sci ; 20(15)2019 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-31382684

RESUMO

About 15% of higher plants have acquired the ability to convert sucrose into fructans. Fructan degradation is catalyzed by fructan exohydrolases (FEHs), which are structurally related to cell wall invertases (CWI). However, the biological function(s) of FEH enzymes in non-fructan species have remained largely enigmatic. In the present study, one maize CWI-related enzyme named Zm-6&1-FEH1, displaying FEH activity, was explored with respect to its substrate specificities, its expression during plant development, and its possible interaction with CWI inhibitor protein. Following heterologous expression in Pichia pastoris and in N. benthamiana leaves, recombinant Zm-6&1-FEH1 revealed substrate specificities of levan and inulin, and also displayed partially invertase activity. Expression of Zm-6&1-FEH1 as monitored by qPCR was strongly dependent on plant development and was further modulated by abiotic stress. To explore whether maize FEH can interact with invertase inhibitor protein, Zm-6&1-FEH1 and maize invertase inhibitor Zm-INVINH1 were co-expressed in N. benthamiana leaves. Bimolecular fluorescence complementation (BiFC) analysis and in vitro enzyme inhibition assays indicated productive complex formation. In summary, the results provide support to the hypothesis that in non-fructan species FEH enzymes may modulate the regulation of CWIs.


Assuntos
Glicosídeo Hidrolases/genética , Folhas de Planta/enzimologia , Zea mays/enzimologia , beta-Frutofuranosidase/genética , Sequência de Aminoácidos , Metabolismo dos Carboidratos/genética , Frutanos/genética , Frutanos/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Glicosídeo Hidrolases/química , Folhas de Planta/genética , Plantas Geneticamente Modificadas/enzimologia , Plantas Geneticamente Modificadas/genética , Especificidade por Substrato , Tabaco/enzimologia , Tabaco/genética , Zea mays/genética , beta-Frutofuranosidase/antagonistas & inibidores
11.
BMC Plant Biol ; 19(1): 310, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31307401

RESUMO

BACKGROUND: The hypersensitive defense response (HR) in plants is a fast, localized necrotic response around the point of pathogen ingress. HR is usually triggered by a pathogen recognition event mediated by a nucleotide-binding site, leucine-rich repeat (NLR) protein. The autoactive maize NLR gene Rp1-D21 confers a spontaneous HR response in the absence of pathogen recognition. Previous work identified a set of loci associated with variation in the strength of Rp1-D21-induced HR. A polygalacturonase gene homolog, here termed ZmPGH1, was identified as a possible causal gene at one of these loci on chromosome 7. RESULTS: Expression of ZmPGH1 inhibited the HR-inducing activity of both Rp1-D21 and that of another autoactive NLR, RPM1(D505V), in a Nicotiana benthamiana transient expression assay system. Overexpression of ZmPGH1 in a transposon insertion line of maize was associated with suppression of chemically-induced programmed cell death and with suppression of HR induced by Rp1-D21 in maize plants grown in the field. CONCLUSIONS: ZmPGH1 functions as a suppressor of programmed cell death induced by at least two autoactive NLR proteins and by two chemical inducers. These findings deepen our understanding of the control of the HR in plants.


Assuntos
Apoptose/fisiologia , Proteínas de Plantas/fisiologia , Poligalacturonase/fisiologia , Zea mays/fisiologia , Apoptose/genética , Mapeamento Cromossômico , Cromossomos de Plantas , Genes de Plantas , Leucina , Proteínas de Plantas/química , Proteínas de Plantas/genética , Poligalacturonase/química , Poligalacturonase/genética , Recombinação Genética , Sequências Repetitivas de Aminoácidos , Tabaco/genética , Zea mays/enzimologia , Zea mays/genética , Zea mays/imunologia
12.
Int J Mol Sci ; 20(13)2019 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-31284569

RESUMO

Drought adversely affects crop growth and yields. The cloning and characterization of drought- or abscisic acid (ABA)-inducible promoters is of great significance for their utilization in the genetic improvement of crop resistance. Our previous studies have shown that maize sulfite oxidase (SO) has a sulfite-oxidizing function and is involved in the drought stress response. However, the promoter of the maize SO gene has not yet been characterized. In this study, the promoter (ZmSOPro, 1194 bp upstream region of the translation initiation site) was isolated from the maize genome. The in-silico analysis of the ZmSOPro promoter identified several cis-elements responsive to the phytohormone ABA and drought stress such as ABA-responsive element (ABRE) and MYB binding site (MBS), besides a number of core cis-acting elements, such as TATA-box and CAAT-box. A 5' RACE (rapid amplification of cDNA ends) assay identified an adenine residue as the transcription start site of the ZmSO. The ZmSOPro activity was detected by ß-glucuronidase (GUS) staining at nearly all developmental stages and in most plant organs, except for the roots in transgenic Arabidopsis. Moreover, its activity was significantly induced by ABA and drought stress. The 5'-deletion mutant analysis of the ZmSOPro in tobacco plants revealed that a 119-bp fragment in the ZmSOPro (upstream of the transcription start site) is a minimal region, which is required for its high-level expression. Moreover, the minimal ZmSOPro was significantly activated by ABA or drought stress in transgenic plants. Further mutant analysis indicated that the MBS element in the minimal ZmSOPro region (119 bp upstream of the transcription start site) is responsible for ABA and drought-stress induced expression. These results improve our understanding of the transcriptional regulation mechanism of the ZmSO gene, and the characterized 119-bp promoter fragment could be an ideal candidate for drought-tolerant gene engineering in both monocot and dicot crops.


Assuntos
Ácido Abscísico/farmacologia , Secas , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Regiões Promotoras Genéticas , Sulfito Oxidase/genética , Zea mays/enzimologia , Arabidopsis/genética , Pareamento de Bases/genética , Sequência de Bases , Fluorescência , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glucuronidase/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Estresse Fisiológico/efeitos dos fármacos , Sulfito Oxidase/metabolismo , Zea mays/genética
13.
Photosynth Res ; 142(2): 153-167, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31325077

RESUMO

The engineering process of C4 photosynthesis into C3 plants requires an increased activity of phosphoenolpyruvate carboxylase (PEPC) in the cytosol of leaf mesophyll cells. The literature varies on the physiological effect of transgenic maize (Zea mays) PEPC (ZmPEPC) leaf expression in Oryza sativa (rice). Therefore, to address this issue, leaf-atmosphere CO2 and 13CO2 exchanges were measured, both in the light (at atmospheric O2 partial pressure of 1.84 kPa and at different CO2 levels) and in the dark, in transgenic rice expressing ZmPEPC and wild-type (WT) plants. The in vitro PEPC activity was 25 times higher in the PEPC overexpressing (PEPC-OE) plants (~20% of maize) compared to the negligible activity in WT. In the PEPC-OE plants, the estimated fraction of carboxylation by PEPC (ß) was ~6% and leaf net biochemical discrimination against 13CO2[Formula: see text] was ~ 2‰ lower than in WT. However, there were no differences in leaf net CO2 assimilation rates (A) between genotypes, while the leaf dark respiration rates (Rd) over three hours after light-dark transition were enhanced (~ 30%) and with a higher 13C composition [Formula: see text] in the PEPC-OE plants compared to WT. These data indicate that ZmPEPC in the PEPC-OE rice plants contributes to leaf carbon metabolism in both the light and in the dark. However, there are some factors, potentially posttranslational regulation and PEP availability, which reduce ZmPEPC activity in vivo.


Assuntos
Atmosfera/química , Dióxido de Carbono/metabolismo , Isótopos de Carbono/química , Oryza/metabolismo , Fosfoenolpiruvato Carboxilase/metabolismo , Folhas de Planta/metabolismo , Zea mays/enzimologia , Zea mays/genética , Respiração Celular , Malatos/metabolismo , Células do Mesofilo/metabolismo , Fotossíntese , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas
14.
Planta ; 250(5): 1521-1538, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31346803

RESUMO

MAIN CONCLUSION: 97 ZmPP2Cs were clustered into 10 subfamilies with biased subfamily evolution and lineage-specific expansion. Segmental duplication after the divergence of maize and sorghum might have led to primary expansion of ZmPP2Cs. The protein phosphatase 2C (PP2C) enzymes control many stress responses and developmental processes in plants. In Zea mays, a comprehensive understanding of the evolution and expansion of the PP2C family is still lacking. In the current study, 97 ZmPP2Cs were identified and clustered into 10 subfamilies. Through the analysis of the PP2C family in monocots, the ZmPP2C subfamilies displayed biased subfamily molecular evolution and lineage-specific expansion, as evidenced by their differing numbers of member genes, expansion and evolutionary rates, conserved subdomains, chromosomal distributions, expression levels, responsive-regulatory elements and regulatory networks. Moreover, while segmental duplication events have caused the primary expansion of the ZmPP2Cs, the majority of their diversification occurred following the additional whole-genome duplication that took place after the divergence of maize and sorghum (Sorghum bicolor). After this event, the PP2C subfamilies showed asymmetric evolutionary rates, with the D, F2 and H subfamily likely the most closely to resemble its ancestral subfamily's genes. These findings could provide novel insights into the molecular evolution and expansion of the PP2C family in maize, and lay the foundation for the functional analysis of these enzymes in maize and related monocots.


Assuntos
Evolução Molecular , Genômica , Proteína Fosfatase 2C/genética , Zea mays/enzimologia , Família Multigênica , Proteínas de Plantas/genética , Sorghum/genética , Zea mays/genética
15.
Pestic Biochem Physiol ; 157: 60-68, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31153478

RESUMO

A series of novel substituted oxazole isoxazole carboxamides derivatives were designed on the basis of active subunit combination. Forty-four novel compounds were synthesized by an efficient one-pot procedure under microwave irradiation. The bioactivity was evaluated as herbicide safener against the injury of chlorsulfuron. It was found that most of the synthesized compounds displayed remarkable protection against chlorsulfuron via enhanced glutathione content and glutathione S transferase activity. Especially compound I-11 exhibited better bioactivity than the safeners isoxadifen-ethyl and R-28725. Molecular docking simulations suggested that the target compounds could compete with chlorsulfuron in the active site of acetolactate synthase, which could explain the protective effects of safeners. The present work demonstrates that the target compounds containing oxazole isoxazole groups could be considered as potential candidates for developing novel safeners in the future.


Assuntos
Herbicidas/química , Herbicidas/farmacologia , Isoxazóis/química , Oxazóis/química , Sulfonamidas/farmacologia , Triazinas/farmacologia , Acetolactato Sintase/genética , Acetolactato Sintase/metabolismo , Ativação Enzimática/efeitos dos fármacos , Glutationa/metabolismo , Glutationa Transferase/metabolismo , Relação Estrutura-Atividade , Zea mays/enzimologia
16.
J Anim Sci ; 97(8): 3390-3398, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31162527

RESUMO

Two experiments were conducted to test the hypothesis that a corn-expressed phytase increases growth performance, bone measurements, and nutrient digestibility by young growing pigs, if added to diets that are deficient in Ca and P. In Exp. 1, 60 pigs (initial BW: 10.78 ± 0.67 kg) were randomly allotted to 6 dietary treatments that included a positive control diet (PC; 0.70% total Ca and 0.60% total P) and a negative control diet (NC; 0.50% total Ca and 0.42% total P). Four additional diets were formulated by supplementing the NC diet with 250, 500, 1,000, or 1,500 phytase units (FTU)/kg. Diets were fed for 28 d and the individual BW of pigs on days 1 and 28 were recorded. Fecal samples were collected from days 25 to 27 to calculate apparent total tract digestibility (ATTD) of Ca and P. On the last day of the experiment, all pigs were euthanized, and the left femur was removed and analyzed for ash, Ca, and P. Results indicated that growth performance, ATTD of Ca and P, and bone ash measurements were reduced (P < 0.05) in NC fed pigs compared with PC fed pigs. However, growth performance, ATTD of Ca and P, and bone ash measurements were improved (linear and quadratic, P < 0.05) by including increasing concentrations of phytase to the NC diet. In Exp. 2, experimental procedures were similar to those used in Exp. 1. Forty-eight pigs (initial BW: 11.15 ± 0.85 kg) were randomly allotted to 6 dietary treatments in a 28-d experiment. Treatments included a PC diet, an NC diet, and 4 diets in which 500 or 1,000 FTU/kg of either the corn-expressed phytase or a commercial microbial phytase were added to the NC diet. Pigs fed the NC diet had reduced (P < 0.01) final BW, ADG, G:F, and bone ash concentrations compared with pigs fed the PC diet. When 500 FTU/kg phytase was fed, no differences were observed in growth performance or bone ash measurements between phytase sources, and there were no differences in growth performance among pigs fed 1,000 FTU/kg of either phytase source or the PC diet. However, regardless of concentration or source of phytase, pigs fed the PC diet had greater (P < 0.001) amount of bone ash, bone Ca, and bone P compared with pigs fed phytase diets. In conclusion, the corn-expressed phytase is effective in improving growth performance, Ca and P digestibility, and bone measurements in pigs fed diets that are deficient in Ca and P.


Assuntos
6-Fitase/farmacologia , Cálcio na Dieta/metabolismo , Escherichia coli/enzimologia , Fósforo na Dieta/metabolismo , Suínos/fisiologia , Zea mays/enzimologia , Ração Animal/análise , Animais , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/fisiologia , Dieta/veterinária , Digestão/efeitos dos fármacos , Proteínas de Escherichia coli/farmacologia , Fezes/química , Feminino , Trato Gastrointestinal/metabolismo , Masculino , Minerais , Distribuição Aleatória , Ganho de Peso/efeitos dos fármacos , Zea mays/genética
17.
Nat Plants ; 5(7): 755-765, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31235877

RESUMO

In C4 grasses of agronomical interest, malate shuttled into the bundle sheath cells is decarboxylated mainly by nicotinamide adenine dinucleotide phosphate (NADP)-malic enzyme (C4-NADP-ME). The activity of C4-NADP-ME was optimized by natural selection to efficiently deliver CO2 to Rubisco. During its evolution from a plastidic non-photosynthetic NADP-ME, C4-NADP-ME acquired increased catalytic efficiency, tetrameric structure and pH-dependent inhibition by its substrate malate. Here, we identified specific amino acids important for these C4 adaptions based on strict differential conservation of amino acids, combined with solving the crystal structures of maize and sorghum C4-NADP-ME. Site-directed mutagenesis and structural analyses show that Q503, L544 and E339 are involved in catalytic efficiency; E339 confers pH-dependent regulation by malate, F140 is critical for the stabilization of the oligomeric structure and the N-terminal region is involved in tetramerization. Together, the identified molecular adaptations form the basis for the efficient catalysis and regulation of one of the central biochemical steps in C4 metabolism.


Assuntos
Malato Desidrogenase/química , Malato Desidrogenase/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Sorghum/enzimologia , Zea mays/enzimologia , Motivos de Aminoácidos , Biocatálise , Domínio Catalítico , Concentração de Íons de Hidrogênio , Malato Desidrogenase/genética , Malatos/metabolismo , Fotossíntese , Proteínas de Plantas/genética , Sorghum/química , Sorghum/genética , Zea mays/química , Zea mays/genética
18.
Plant Physiol Biochem ; 141: 415-422, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31229926

RESUMO

This study aimed to investigate the possible alleviating effect of chitosan on salt-induced growth retardation and oxidative stress and to elucidate whether this effect is linked to activation of mitochondrial respiration on the basis of alternative respiration in maize seedlings. Salt stress significantly reduced root length and plant height in comparison to the control, whereas foliar application of chitosan ameliorated the adverse effect of salinity to a certain degree. Moreover, chitosan resulted in plant growth promotion as compared to unstressed seedlings. The separate applications of chitosan and salt had a stimulatory effect on the activities of antioxidant enzymes; however, combined application of chitosan and salt were more effective than that of chitosan or salt alone. Similarly, mitochondrial total respiration rate (Vt) and alternative respiration capacity (Valt) were increased by separate applications of chitosan and salt; however, the combination of chitosan and salt gave the highest values for these parameters. The highest values of Valt/Vt was recorded at seedlings treated with salt plus chitosan. Similarly, cytochrome respiration capacity was also increased by chitosan in both stress-free and stressed conditions. In addition, AOX1, encoding alternative oxidase, was significantly upregulated by chitosan and/or salt. The maximum transcript level was recorded at seedlings treated with salt plus chitosan. Chitosan also significantly decreased superoxide anion and hydrogen peroxide contents and lipid peroxidation level under normal and the stressed conditions. These results suggest that the mitigating effect of chitosan on salt stress is linked to activation of alternative respiration at biochemical and molecular level.


Assuntos
Quitosana/química , Regulação da Expressão Gênica de Plantas , Proteínas Mitocondriais/metabolismo , Oxirredutases/metabolismo , Proteínas de Plantas/metabolismo , Tolerância ao Sal , Plântula/genética , Zea mays/genética , Antioxidantes/metabolismo , Citocromos/metabolismo , Perfilação da Expressão Gênica , Peroxidação de Lipídeos , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Estresse Oxidativo , Oxirredutases/genética , Proteínas de Plantas/genética , RNA/metabolismo , Estresse Fisiológico , Zea mays/enzimologia
19.
Int J Oncol ; 54(6): 2080-2094, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31081059

RESUMO

Amine oxidases, which contribute to the regulation of polyamine levels, catalyze the oxidative deamination of polyamines to generate H2O2 and aldehyde(s). In this study, and at least to the best of our knowledge, maize polyamine oxidase (ZmPAO) was used for the first time with the aim of identifying a novel strategy for cancer therapy. The cytotoxicity and the mechanisms of cell death induced by the enzymatic oxidation products of polyamine generated by ZmPAO were investigated. Exogenous spermine and ZmPAO treatment decreased cell viability in a spermine dose­ and time­dependent manner, particularly, the viability of the multidrug­resistant (MDR) colon adenocarcinoma cells, LoVo DX, when compared with drug­sensitive ones (LoVo WT). Further analyses revealed that H2O2 derived from spermine was mainly responsible for the cytotoxicity. Flow cytometric analysis revealed that treatment with ZmPAO and spermine increased the apoptotic population of LoVo WT and LoVo DX cells. In addition, we found that treatment with ZmPAO and spermine markedly reduced mitochondrial membrane potential in the LoVo DX cells, in agreement with the results of cell viability and apoptosis assays. Transmission electron microscopic observations supported the involvement of mitochondrial depolarization in the apoptotic process. Therefore, the dysregulation of polyamine metabolism in tumor cells may be a potential therapeutic target. In addition, the development of MDR tumor cells is recognized as a major obstacle in cancer therapy. Therefore, the design of a novel therapeutic strategy based on the use of this combination may be taken into account, making this approach attractive mainly in treating MDR cancer patients.


Assuntos
Adenocarcinoma/metabolismo , Neoplasias do Colo/metabolismo , Peróxido de Hidrogênio/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/farmacologia , Espermina/farmacologia , Zea mays/enzimologia , Adenocarcinoma/tratamento farmacológico , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Colo/tratamento farmacológico , Relação Dose-Resposta a Droga , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Sinergismo Farmacológico , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Proteínas de Plantas/farmacologia , Espermidina/farmacologia , Fatores de Tempo
20.
Planta ; 250(2): 573-588, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31127375

RESUMO

MAIN CONCLUSION: The information on core components in maize polycomb repressive complex 2 (PRC2) are updated at a genome-wide scale, and the protein-protein interaction networks of PRC2 components are further provided in maize. The evolutionarily conserved polycomb group (PcG) proteins form multi-subunits polycomb repressive complexes (PRCs) that repress gene expression via chromatin condensation. In Arabidopsis, three distinct PRC2s have been identified, each determining a specific developmental program with partly functional redundancy. However, the core components and biological functions of PRC2 in cereals remain obscure. Here, we updated the information on maize PRC2 components at a genome-wide scale. Maize PRC2 subunits are highly duplicated, with five MSI1, three E(z), two ESC and two Su(z)12 homologs. ZmFIE1 is preferentially expressed in the endosperm, whereas the remaining are broadly expressed in many tissues. ZmCLF/MEZ1 and ZmFIE1 are maternally expressed imprinted genes, in contrast to the paternal-dominantly expression of ZmFIE2 in the endosperm. In maize, E(z) members likely provide a scaffold for assembling PRC2 complexes, whereas Su(z)12 and p55/MSI1-like proteins together reinforce the complex; ESC members probably determine its specificity: FIE1-PRC2 regulates endosperm cell development, whereas FIE2-PRC2 controls other cell types. The duplicated Brassicaceae-specific MEA and FIS2 also directly interact with maize PRC2 members. Together, this study establishes a roadmap for protein-protein interactions of maize PRC2 components, providing new insights into their functions in the growth and development of cereals.


Assuntos
Complexo Repressor Polycomb 2/metabolismo , Zea mays/enzimologia , Alelos , Arabidopsis/enzimologia , Arabidopsis/genética , Endosperma/enzimologia , Endosperma/genética , Endosperma/ultraestrutura , Epigenômica , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Complexo Repressor Polycomb 2/genética , Domínios Proteicos , Técnicas do Sistema de Duplo-Híbrido , Zea mays/genética , Zea mays/ultraestrutura
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