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1.
Biotechnol Adv ; 46: 107671, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33242576

RESUMO

Horizontal gene transfer (HGT) refers to the movement of genetic material between distinct species by means other than sexual reproduction. HGT has contributed tremendously to the genome plasticity and adaptive evolution of prokaryotes and certain unicellular eukaryotes. The evolution of green plants from chlorophyte algae to angiosperms and from water to land represents a process of adaptation to diverse environments, which has been facilitated by acquisition of genetic material from other organisms. In this article, we review the occurrence of HGT in major lineages of green plants, including chlorophyte and charophyte green algae, bryophytes, lycophytes, ferns, and seed plants. In addition, we discuss the significance of horizontally acquired genes in the adaptive innovations of green plants and their potential applications to crop breeding and improvement.

2.
Plant Biotechnol J ; 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32738177

RESUMO

Hybrid breeding has been shown to effectively increase rice productivity. However, identifying desirable hybrids out of numerous potential combinations is a daunting challenge. Genomic selection holds great promise for accelerating hybrid breeding by enabling early selection before phenotypes are measured. With the recent advances in multi-omic technologies, hybrid prediction based on transcriptomic and metabolomic data has received increasing attention. However, the current omic-based hybrid prediction has ignored parental phenotypic information, which is of fundamental importance in plant breeding. In this study, we integrated parental phenotypic information into various multi-omic prediction models applied in hybrid breeding of rice and compared the predictabilities of 15 combinations from four sets of predictors from the parents, that is genome, transcriptome, metabolome and phenome. The predictability for each combination was evaluated using the best linear unbiased prediction and a modified fast HAT method. We found significant interactions between predictors and traits in predictability, but joint prediction with various combinations of the predictors significantly improved predictability relative to prediction of any single source omic data for each trait investigated. Incorporation of parental phenotypic data into various omic predictors increased the predictability, averagely by 13.6%, 54.5%, 19.9% and 8.3%, for grain yield, number of tillers per plant, number of grains per panicle and 1000 grain weight, respectively. Among nine models of incorporating parental traits, the AD-All model was the most effective one. This novel strategy of incorporating parental phenotypic data into multi-omic prediction is expected to improve hybrid breeding progress, especially with the development of high-throughput phenotyping technologies.

3.
Sci Total Environ ; 724: 138200, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32408449

RESUMO

Dengue fever (DF) is a common and rapidly spreading vector-borne viral disease in tropical and subtropical regions. In recent years, in China, DF still poses an increasing threat to public health in many cities; but the incidence shows significant spatiotemporal differences. The purpose of this study was to identify the key factors affecting the spatial and temporal distribution of DF. We collected natural environmental and socio-economic data for two adjacent cities, Guangzhou (73 variables) and Foshan (71 variables), with the most DF cases in China. We performed random forest modelling to rank the factors according to their level of importance, and used negative binomial regression analysis to compare the risk factors between outbreak years and non-outbreak years. The natural environmental factors contributing to DF incidence for Guangzhou were temperature (relative risk (RR) = 18.80, 95% confidence interval (CI) = 3.11-113.67), humidity (RR = 1.85, 95% CI = 1.17-2.90) and green area (RR = 12.11, 95% CI = 6.14-55.50), and for Foshan was forest coverage (RR = 5.83, 95% CI = 2.72-12.45). Socio-economic impact were shown in Guangzhou with foreign visitor (RR = 1.18, 95% CI = 1.05-1.34) and oversea air passenger transport (RR = 7.34, 95% CI = 2.26-23.86); in Foshan, with oversea tourism (RR = 1.65, 95% CI = 1.34-2.04); and in Guangzhou-Foshan, with the development of intercity metro (RR = 1.26, 95% CI = 1.10-1.44). The difference between the two cities was the greater impact of the foreign visitor, green spaces and climate factor on DF in Guangzhou; the impact of the construction of intercity metro; and the more significant impact of oversea tourism on DF in Foshan. Our results suggest meaningful clues to public health authorities implementing joint interventions on DF prevention and early warning, to increase health education on DF prevention for international visitors and oversea travelers, and cross-city metro passengers; using rapid body temperature detection in public places such as airports, metros and parks can help detect cases early.


Assuntos
Dengue , China , Cidades , Humanos , Fatores de Risco , Fatores Socioeconômicos
4.
New Phytol ; 227(5): 1417-1433, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32433775

RESUMO

Plants maintain a dynamic balance between plant growth and stress tolerance to optimise their fitness and ensure survival. Here, we investigated the roles of a clade A type 2C protein phosphatase (PP2C)-encoding gene, OsPP2C09, in regulating the trade-off between plant growth and drought tolerance in rice (Oryza sativa L.). The OsPP2C09 protein interacted with the core components of abscisic acid (ABA) signalling and showed PP2C phosphatase activity in vitro. OsPP2C09 positively affected plant growth but acted as a negative regulator of drought tolerance through ABA signalling. Transcript and protein levels of OsPP2C09 were rapidly induced by exogenous ABA treatments, which suppressed excessive ABA signalling and plant growth arrest. OsPP2C09 transcript levels in roots were much higher than those in shoots under normal conditions. After ABA, polyethylene glycol and dehydration treatments, the accumulation rate of OsPP2C09 transcripts in roots was more rapid and greater than that in shoots. This differential expression between the roots and shoots may increase the plant's root-to-shoot ratio under drought-stress conditions. This study sheds new light on the roles of OsPP2C09 in coordinating plant growth and drought tolerance. In particular, we propose that OsPP2C09-mediated ABA desensitisation contributes to root elongation under drought-stress conditions in rice.

5.
BMC Plant Biol ; 20(1): 30, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31959100

RESUMO

BACKGROUND: Nicotiana tabacum is an important economic crop. Topping, a common agricultural practice employed with flue-cured tobacco, is designed to increase leaf nicotine contents by increasing nicotine biosynthesis in roots. Many genes are found to be differentially expressed in response to topping, particularly genes involved in nicotine biosynthesis, but comprehensive analyses of early transcriptional responses induced by topping are not yet available. To develop a detailed understanding of the mechanisms regulating nicotine biosynthesis after topping, we have sequenced the transcriptomes of Nicotiana tabacum roots at seven time points following topping. RESULTS: Differential expression analysis revealed that 4830 genes responded to topping across all time points. Amongst these, nine gene families involved in nicotine biosynthesis and two gene families involved in nicotine transport showed significant changes during the immediate 24 h period following topping. No obvious preference to the parental species was detected in the differentially expressed genes (DEGs). Significant changes in transcript levels of nine genes involved in nicotine biosynthesis and phytohormone signal transduction were validated by qRT-PCR assays. 549 genes encoding transcription factors (TFs), found to exhibit significant changes in gene expression after topping, formed 15 clusters based on similarities of their transcript level time-course profiles. 336 DEGs involved in phytohormone signal transduction, including genes functionally related to the phytohormones jasmonic acid, abscisic acid, auxin, ethylene, and gibberellin, were identified at the earliest time point after topping. CONCLUSIONS: Our research provides the first detailed analysis of the early transcriptional responses to topping in N. tabacum, and identifies excellent candidates for further detailed studies concerning the regulation of nicotine biosynthesis in tobacco roots.


Assuntos
Genes de Plantas , Nicotina/biossíntese , Tabaco/genética , Transcriptoma , Produção Agrícola/métodos , Perfilação da Expressão Gênica , Raízes de Plantas/metabolismo , Tabaco/metabolismo
6.
Heredity (Edinb) ; 124(1): 122-134, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31358987

RESUMO

Seed filling is a dynamic process that determines seed size and nutritional quality. This time-dependent trait follows a logistic (S-shaped) growth curve that can be described by a logistic function, with parameters of biological relevance. When compared between genotypes, the filling dynamics variations are explained by the differences of parameter values; as such, the parameter estimates can be considered as "traits" for genetic analysis to identify loci that are associated with the seed-filling process. We carried out genetic and genomic analysis of the seed-filling process in maize, using a recombinant inbred line (RIL) population derived from the two inbred lines with contrasting seed-filling dynamics. We recorded seed dry weight at 14 time points after pollination, spanning the early filling phases to the late maturation stages. Fitting these data to a logistic model allowed for estimating 12 characteristic parameters that can be used to meaningfully describe the seed-filling process. Quantitative trait locus (QTL) mapping of these parameters identified a total of 90 nonredundant loci. Using bulked segregant RNA-sequencing (BSR-seq) analysis, we identified eight genes that showed differential gene expression patterns at multiple time points between the extreme pools, and these genes co-localize with the mapped QTL regions. Two of the eight genes, GRMZM2G391936 and GRMZM2G008263, are implicated in starch and sucrose metabolism, and biosynthesis of secondary metabolites that are well known for playing a vital role in seed filling. This study suggests that the logistic model-based approach can efficiently identify genetic loci that regulate dynamic developing traits.

7.
Int J Mol Sci ; 20(23)2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31775351

RESUMO

Reducing nitrogen (N) input is a key measure to achieve a sustainable rice production in China, especially in Jiangsu Province. Tiller is the basis for achieving panicle number that plays as a major factor in the yield determination. In actual production, excessive N is often applied in order to produce enough tillers in the early stages. Understanding how N regulates tillering in rice plants is critical to generate an integrative management to reduce N use and reaching tiller number target. Aiming at this objective, we utilized RNA sequencing and weighted gene co-expression network analysis (WGCNA) to compare the transcriptomes surrounding the shoot apical meristem of indica (Yangdao6, YD6) and japonica (Nipponbare, NPB) rice subspecies. Our results showed that N rate influenced tiller number in a different pattern between the two varieties, with NPB being more sensitive to N enrichment, and YD6 being more tolerant to high N rate. Tiller number was positively related to N content in leaf, culm and root tissue, but negatively related to the soluble carbohydrate content, regardless of variety. Transcriptomic comparisons revealed that for YD6 when N rate enrichment from low (LN) to medium (MN), it caused 115 DEGs (LN vs. MN), from MN to high level (HN) triggered 162 DEGs (MN vs. HN), but direct comparison of low with high N rate showed a 511 DEGs (LN vs. HN). These numbers of DEG in NPB were 87 (LN vs. MN), 40 (MN vs. HN), and 148 (LN vs. HN). These differences indicate that continual N enrichment led to a bumpy change at the transcription level. For the reported sixty-five genes which affect tillering, thirty-six showed decent expression in SAM at tiller starting phase, among them only nineteen being significantly influenced by N level, and two genes showed significant interaction between N rate and variety. Gene ontology analysis revealed that the majority of the common DEGs are involved in general stress responses, stimulus responses, and hormonal signaling process. WGCNA network identified twenty-two co-expressing gene modules and ten candidate hubgenes for each module. Several genes associated with tillering and N rate fall on the related modules. These indicate that there are more genes participating in tillering regulation in response to N enrichment.


Assuntos
Redes Reguladoras de Genes/efeitos dos fármacos , Meristema/genética , Nitrogênio/farmacologia , Oryza/genética , Proteínas de Plantas/genética , Brotos de Planta/genética , Transcriptoma , Perfilação da Expressão Gênica , Meristema/efeitos dos fármacos , Oryza/classificação , Oryza/efeitos dos fármacos , Brotos de Planta/efeitos dos fármacos , Análise de Sequência de RNA
8.
Breed Sci ; 69(3): 420-428, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31598074

RESUMO

Yield improvement is a top priority for maize breeding. Kernel size and weight are important determinants of maize grain yield. In this study, a recombinant inbred line (RIL) population and an association panel were used to identify quantitative trait loci (QTLs) for four maize kernel-related traits: kernel length, width, thickness and 100-kernel weight. Twenty-seven QTLs were identified for kernel-related traits across three environments and the best linear unbiased predictions (BLUPs) of each trait by linkage analysis, and four QTLs were stably detected in more than two environments. Additionally, 29 single nucleotide polymorphisms (SNPs) were identified as significantly associated with the four kernel-related traits and BLUPs by genome-wide association study, and two loci could be stably detected in both environments. In total, four QTLs/SNPs were co-associated with various traits in both populations. Using combined-linkage analysis and association mapping, PZE-101066560 on chromosome 1, associated with kernel width and with 100-kernel weight in the association panel, was co-localized within the QTL interval of qKW1-3 for kernel width in the RILs. Two annotated genes in the candidate region were considered as potential candidate genes. The QTLs and candidate genes identified here will facilitate molecular breeding for grain yield improvement in maize.

9.
Genes (Basel) ; 10(10)2019 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-31581635

RESUMO

Root system plays an essential role in water and nutrient acquisition in plants. Understanding the genetic basis of root development will be beneficial for breeding new cultivars with efficient root system to enhance resource use efficiency in maize. Here, the natural variation of 13 root and 3 shoot traits was evaluated in 297 maize inbred lines and genome-wide association mapping was conducted to identify SNPs associated with target traits. All measured traits exhibited 2.02- to 21.36-fold variations. A total of 34 quantitative trait loci (QTLs) were detected for 13 traits, and each individual QTL explained 5.7% to 15.9% of the phenotypic variance. Three pleiotropic QTLs involving five root traits were identified; SNP_2_104416607 was associated with lateral root length (LRL), root surface area (RA), root length between 0 and 0.5mm in diameter (RL005), and total root length (TRL); SNP_2_184016997 was associated with RV and RA, and SNP_4_168917747 was associated with LRL, RA and TRL. The expression levels of candidate genes in root QTLs were evaluated by RNA-seq among three long-root lines and three short-root lines. A total of five genes that showed differential expression between the long- and short-root lines were identified as promising candidate genes for the target traits. These QTLs and the potential candidate genes are important source data to understand root development and genetic improvement of root traits in maize.


Assuntos
Raízes de Plantas/genética , Zea mays/genética , Cruzamento , Mapeamento Cromossômico , Perfilação da Expressão Gênica/métodos , Estudo de Associação Genômica Ampla , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Locos de Características Quantitativas/genética , Plântula/genética , Plântula/crescimento & desenvolvimento
10.
Int J Mol Sci ; 20(18)2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31491955

RESUMO

Japonica and indica are two important subspecies in cultivated Asian rice. Irradiation is a classical approach to induce mutations and create novel germplasm. However, little is known about the differential response between japonica and indica rice after γ radiation. Here, we utilized the RNA sequencing and Weighted Gene Co-expression Network Analysis (WGCNA) to compare the transcriptome differences between japonica Nipponbare (NPB) and indica Yangdao6 (YD6) in response to irradiation. Japonica subspecies are more sensitive to irradiation than the indica subspecies. Indica showed a higher seedling survival rate than japonica. Irradiation caused more extensive DNA damage in shoots than in roots, and the severity was higher in NPB than in YD6. GO and KEGG pathway analyses indicate that the core genes related to DNA repair and replication and cell proliferation are similarly regulated between the varieties, however the universal stress responsive genes show contrasting differential response patterns in japonica and indica. WGCNA identifies 37 co-expressing gene modules and ten candidate hub genes for each module. This provides novel evidence indicating that certain peripheral pathways may dominate the molecular networks in irradiation survival and suggests more potential target genes in breeding for universal stress tolerance in rice.


Assuntos
Raios gama , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Redes Reguladoras de Genes , Oryza/genética , Oryza/efeitos da radiação , Transcriptoma , Biologia Computacional/métodos , Dano ao DNA/genética , Perfilação da Expressão Gênica , Ontologia Genética , Tolerância a Radiação/genética , Plântula/genética , Plântula/efeitos da radiação
11.
Genes (Basel) ; 10(9)2019 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-31480272

RESUMO

ZmPGP1, involved in the polar auxin transport, has been shown to be associated with plant height, leaf angle, yield traits, and root development in maize. To explore natural variation and domestication selection of ZmPGP1, we re-sequenced the ZmPGP1 gene in 349 inbred lines, 68 landraces, and 32 teosintes. Sequence polymorphisms, nucleotide diversity, and neutral tests revealed that ZmPGP1 might be selected during domestication and improvement processes. Marker-trait association analysis in inbred lines identified 11 variants significantly associated with 4 plant architecture and 5 ear traits. SNP1473 was the most significant variant for kernel length and ear grain weight. The frequency of an increased allele T was 40.6% in teosintes, and it was enriched to 60.3% and 89.1% during maize domestication and improvement. This result revealed that ZmPGP1 may be selected in the domestication and improvement process, and significant variants could be used to develop functional markers to improve plant architecture and ear traits in maize.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Proteínas de Plantas/genética , Polimorfismo Genético , Seleção Artificial , Zea mays/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Domesticação , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Característica Quantitativa Herdável , Zea mays/crescimento & desenvolvimento
12.
Plant Sci ; 286: 17-27, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31300138

RESUMO

The plant-specific gibberellic acid (GA)-stimulated transcript gene family is critical for plant growth and development. There are 10 family members in rice (Oryza sativa), known as OsGASRs. However, few have been functionally characterized. Here, we investigated the function of OsGASR9 in rice. OsGASR9 transcripts were detected in various tissues, with the lowest and highest levels in leaves and panicles, respectively. Greater mRNA levels accumulated in young, compared with in old, panicles and spikelets. OsGASR9 localized to the plasma membrane, cytoplasm and nucleus. Transgenic RNA interference-derived lines in the Zhonghua 11 background exhibited reduced plant height, grain size and yield compared with the wild-type. The two osgasr9 mutants in the Nipponbare background showed similar phenotypes. Conversely, the overexpression of OsGASR9 in the two backgrounds increased plant height and grain size. A significantly increased grain yield per plant was also observed in the overexpression lines having a Nipponbare background. Furthermore, by measuring the GA-induced lengths of the second leaf sheaths and α-amylase activity levels of seeds, we concluded that OsGASR9 is a positive regulator of responses to GA in rice. Thus, OsGASR9 may regulate plant height, grain size and yield through the GA pathway and could have an application value in breeding.


Assuntos
Giberelinas/metabolismo , Oryza/genética , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/genética , Sequência de Aminoácidos , Sequência de Bases , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Família Multigênica , Oryza/crescimento & desenvolvimento , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Interferência de RNA
13.
Mol Phylogenet Evol ; 138: 205-218, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31132519

RESUMO

Colonization of the land by plants was a critical event in the establishment of modern terrestrial ecosystems, and many characteristics of land plants originated during this process, including the emergence of rosette terminal cellulose-synthesizing complexes. Cellulases are non-homologous isofunctional enzymes, encoded by glycosyl hydrolase (GH) gene families. Although the plant GH5_11 gene subfamily is presumed to encode a cell-wall degrading enzyme, its evolutionary and functional characteristics remain unclear. In the present study, we report the evolution of the land plant GH5_11 subfamily, and the functions of its members in terms of cellulase activity, through comprehensive phylogenetic analyses and observation of Arabidopsis mutants. Phylogenetic and sequence similarity analyses reveal that the ancestor of land plants acquired the GH5_11 gene from fungi through a horizontal gene transfer (HGT) event. Subsequently, positive selection with massive gene duplication and loss events contributed to the evolution of this subfamily in land plants. In Arabidopsis and rice, expression of GH5_11 genes are regulated by multiple abiotic stresses, the duplicated genes showing different patterns of expression. The Arabidopsis mutants atgh5_11a and atgh5_11c display low levels of cellulase and endoglucanase activities, with correspondingly high levels of cellulose, implying that the encoded proteins may function as endoglucanases. However, atgh5_11a and atgh5_11c also display an enlarged rosette leaf phenotype, and atgh5_11c is late-flowering under short photoperiods. These observations suggest that plant GH5_11s possess more functions beyond being endonucleases. To summarize, we demonstrate that the ancestor of land plants has acquired GH5_11 gene through HGT, which extends the cellulose degradation complexity. Our investigations illuminate features of part of the molecular framework underlying the origin of land plants and provide a focus on the cellulose degradation pathway.


Assuntos
Arabidopsis/enzimologia , Arabidopsis/genética , Evolução Molecular , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Celulose/metabolismo , Duplicação Gênica , Regulação da Expressão Gênica de Plantas , Transferência Genética Horizontal/genética , Genes de Plantas , Mutagênese/genética , Mutação/genética , Fenótipo , Filogenia , Seleção Genética
14.
Nat Commun ; 10(1): 1949, 2019 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-31028264

RESUMO

Grain protein content (GPC) affects rice nutrition quality. Here, we identify two stable quantitative trait loci (QTLs), qGPC-1 and qGPC-10, controlling GPC in a mapping population derived from indica and japonica cultivars crossing. Map-based cloning reveals that OsGluA2, encoding a glutelin type-A2 precursor, is the candidate gene underlying qGPC-10. It functions as a positive regulator of GPC and has a pleiotropic effect on rice grain quality. One SNP located in OsGluA2 promoter region is associated with its transcript expression level and GPC diversity. Polymorphisms of this nucleotide can divide all haplotypes into low (OsGluA2LET) and high (OsGluA2HET) expression types. Population genetic and evolutionary analyses reveal that OsGluA2LET, mainly present in japonica accessions, originates from wild rice. However, OsGluA2HET, the dominant type in indica, is acquired through mutation of OsGluA2LET. Our results shed light on the understanding of natural variations of GPC between indica and japonica subspecies.


Assuntos
Proteínas de Grãos/metabolismo , Oryza/metabolismo , Mapeamento Cromossômico , Cromossomos de Plantas/genética , Grão Comestível/metabolismo , Haplótipos/genética , Oryza/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas/genética
15.
Rice (N Y) ; 12(1): 5, 2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30706248

RESUMO

BACKGROUND: qPE9-1/DEP1, encoding a G protein γ subunit, has multiple effects on plant architecture, grain size, and yield in rice. The qPE9-1 protein contains an N-terminal G gamma-like (GGL) domain, a putative transmembrane domain, and a C-terminal cysteine-rich domain. However, the roles of each domain remain unclear. RESULTS: In the present study, we focused on the genetic effects of different domains of qPE9-1 in the regulation of grain length and weight. We generated a series of transgenic plants expressing different truncated qPE9-1 proteins through constitutive expression and clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9 strategies. Phenotypic analysis indicated that the complete or long-tailed qPE9-1 contributed to the elongation of grains, while the GGL domain alone and short-tailed qPE9-1 led to short grains. The long C-terminus of qPE9-1 including two or three C-terminal von Willebrand factor type C domains effectively repressed the negative effects of the GGL domain on grain length and weight. qPE9-1-overexpressing lines in a Wuxianggeng 9 (carrying a qpe9-1 allele) background showed increased grain yield per plant, but lodging occurred in some years. CONCLUSIONS: Manipulation of the C-terminal length of qPE9-1 through genetic engineering can be used to generate varieties with various grain lengths and weights according to different requirements in rice breeding. The genetic effects of qPE9-1/qpe9-1 are multidimensional, and breeders should take into account other factors including genetic backgrounds and planting conditions in the use of qPE9-1/qpe9-1.

16.
Materials (Basel) ; 12(3)2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30708994

RESUMO

Carbon composite is widely used in various fields, including the aerospace industry, electrical engineering, transportation engineering, etc. For electrified railways, the pantograph strip utilizes carbon composite as the current collector, which might bear multiple impacts from electrical, mechanical, or thermal aspects, from unwanted arcing, rain, and other diverse operation conditions. In this paper, a thermal shock damage experiment on the carbon composite of a pantograph strip was carried out. The thermal shock processes were realized by the adoption of muffle furnace heating and water cooling. The effect of thermal shock processes on carbon strip porosity, compressive strength, electrical resistivity, and surface topography were studied. In order to verify the mechanism of thermal shock damage to the pantograph strip, the porosity of the pantograph strip is discussed in detail. The results showed that the thermal shock process increased the porosity of the carbon strip and caused reductions in compressive strength and electrical resistivity. The multiple thermal shock processes caused irreversible damage to the pantograph strip, which was attributed to the spillover and scouring of large quantities of water vapor in the pores.

17.
Planta ; 249(3): 879-889, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30460404

RESUMO

MAIN CONCLUSION: Eight variants in ZmHKT1 promoter were significantly associated with root diameter, four haplotypes based on these significant variants were found, and Hap2 has the largest root diameter. Roots play an important role in uptake of water, nutrients and plant anchorage. Identification of gene and corresponding SNPs associated with root traits would enable develop maize lines with better root traits that might help to improve capacity for absorbing nutrients and water acquisition. The genomic sequences of a salt tolerance gene ZmHKT1 was resequenced in 349 maize inbred lines, and the association between nucleotide polymorphisms and seedling root traits was detected. A total of 269 variants in ZmHKT1 were identified, including 226 single nucleotide polymorphisms and 43 insertions and deletions. The gene displayed high level of nucleotide diversity, especially in non-genic regions. A total of 19 variations in untranslated region of ZmHKT1 were found to be associated with six seedling traits. Eight variants in promoter region were significantly associated with average root diameter (ARD), four haplotypes were found based on these significant variants, and Hap2 has the largest ARD. Two SNPs in high-linkage disequilibrium (SNP-415 and SNP 2169) with pleiotropic effects were significantly associated with plant height, root surface area, root volume, and shoot dry weight. This result revealed that ZmHKT1 was an important contributor to the phenotypic variations of seedling root traits in maize, these significant variants could use to develop functional markers to improve root traits.


Assuntos
Proteínas de Transporte de Cátions/genética , Proteínas de Plantas/genética , Raízes de Plantas/anatomia & histologia , Zea mays/genética , Proteínas de Transporte de Cátions/fisiologia , Estudos de Associação Genética , Variação Genética , Proteínas de Plantas/fisiologia , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Polimorfismo de Nucleotídeo Único/genética , Característica Quantitativa Herdável , Plântula/anatomia & histologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Análise de Sequência de DNA , Zea mays/anatomia & histologia , Zea mays/crescimento & desenvolvimento
18.
Plant Biotechnol J ; 17(3): 650-664, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30160362

RESUMO

Heterotrimeric G proteins, which consist of Gα , Gß and Gγ subunits, function as molecular switches that regulate a wide range of developmental processes in plants. In this study, we characterised the function of rice RGG2, which encodes a type B Gγ subunit, in regulating grain size and yield production. The expression levels of RGG2 were significantly higher than those of other rice Gγ -encoding genes in all tissues tested, suggesting that RGG2 plays essential roles in rice growth and development. By regulating cell expansion, overexpression of RGG2 in Nipponbare (NIP) led to reduced plant height and decreased grain size. By contrast, two mutants generated by the clustered, regularly interspaced, short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) system in the Zhenshan 97 (ZS97) background, zrgg2-1 and zrgg2-2, exhibited enhanced growth, including elongated internodes, increased 1000-grain weight and plant biomass and enhanced grain yield per plant (+11.8% and 16.0%, respectively). These results demonstrate that RGG2 acts as a negative regulator of plant growth and organ size in rice. By measuring the length of the second leaf sheath after gibberellin (GA3 ) treatment and the GA-induced α-amylase activity of seeds, we found that RGG2 is also involved in GA signalling. In summary, we propose that RGG2 may regulate grain and organ size via the GA pathway and that manipulation of RGG2 may provide a novel strategy for rice grain yield enhancement.


Assuntos
Grão Comestível/crescimento & desenvolvimento , Subunidades gama da Proteína de Ligação ao GTP/genética , Oryza/genética , Proteínas de Plantas/genética , Sistemas CRISPR-Cas , Grão Comestível/genética , Subunidades gama da Proteína de Ligação ao GTP/fisiologia , Edição de Genes/métodos , Regulação da Expressão Gênica de Plantas , Mutação/genética , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento
19.
Plant Physiol ; 178(4): 1522-1536, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30190417

RESUMO

Polyamines, including putrescine, spermidine, and spermine, play essential roles in a wide variety of prokaryotic and eukaryotic organisms. Rice (Oryza sativa) contains four putative spermidine/spermine synthase (SPMS)-encoding genes (OsSPMS1, OsSPMS2, OsSPMS3, and OsACAULIS5), but none have been functionally characterized. In this study, we used a reverse genetic strategy to investigate the biological function of OsSPMS1 We generated several homozygous RNA interference (RNAi) and overexpression (OE) lines of OsSPMS1 Phenotypic analysis indicated that OsSPMS1 negatively regulates seed germination, grain size, and grain yield per plant. The ratio of spermine to spermidine was significantly lower in the RNAi lines and considerably higher in the OE lines than in the wild type, suggesting that OsSPMS1 may function as a SPMS. S-Adenosyl-l-methionine is a common precursor of polyamines and ethylene biosynthesis. The 1-aminocyclopropane-1-carboxylic acid (ACC) and ethylene contents in seeds increased significantly in RNAi lines and decreased in OE lines, respectively, compared with the wild type. Additionally, the reduced germination rates and growth defects of OE lines could be rescued with ACC treatment. These data suggest that OsSPMS1 affects ethylene synthesis and may regulate seed germination and plant growth by affecting the ACC and ethylene pathways. Most importantly, an OsSPMS1 knockout mutant showed an increase in grain yield per plant in a high-yield variety, Suken118, suggesting that OsSPMS1 is an important target for yield enhancement in rice.


Assuntos
Germinação/fisiologia , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/metabolismo , Sementes/crescimento & desenvolvimento , Espermina Sintase/metabolismo , Aminoácidos Cíclicos/metabolismo , Etilenos/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Homeostase , Oryza/enzimologia , Oryza/genética , Filogenia , Proteínas de Plantas/genética , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Sementes/genética , Sementes/metabolismo , Espermina Sintase/genética
20.
Front Plant Sci ; 9: 1311, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30233634

RESUMO

Maize starch plays a critical role in food processing and industrial application. The pasting properties, the most important starch characteristics, have enormous influence on fabrication property, flavor characteristics, storage, cooking, and baking. Understanding the genetic basis of starch pasting properties will be beneficial for manipulation of starch properties for a given purpose. Genome-wide association studies (GWAS) are becoming a powerful tool for dissecting the complex traits. Here, we carried out GWAS for seven pasting properties of maize starch with a panel of 230 inbred lines and 145,232 SNPs using one single-locus method, genome-wide efficient mixed model association (GEMMA), and three multi-locus methods, FASTmrEMMA, FarmCPU, and LASSO. We totally identified 60 quantitative trait nucleotides (QTNs) for starch pasting properties with these four GWAS methods. FASTmrEMMA detected the most QTNs (29), followed by FarmCPU (19) and LASSO (12), GEMMA detected the least QTNs (7). Of these QTNs, seven QTNs were identified by more than one method simultaneously. We further investigated locations of these significantly associated QTNs for possible candidate genes. These candidate genes and significant QTNs provide the guidance for further understanding of molecular mechanisms of starch pasting properties. We also compared the statistical powers and Type I errors of the four GWAS methods using Monte Carlo simulations. The results suggest that the multi-locus method is more powerful than the single-locus method and a combination of these multi-locus methods could help improve the detection power of GWAS.

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