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1.
Lung Cancer ; 139: 103-110, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31760351

RESUMO

OBJECTIVES: To evaluate the diagnostic accuracy of radiomics method and frozen sections (FS) for the pathological classification of peripheral lung adenocarcinoma manifesting as ground-glass nodules (GGNs) in computer tomography (CT). MATERIALS AND METHODS: A dataset of 831 peripheral lung adenocarcinoma manifesting as GGNs in CT were divided into two cohorts: training cohort (n = 581) and validation cohort (n = 250). Combined with clinical features, the radiomics classifier was trained and validated to distinguish the pathological classification of these nodules. FS diagnoses in the validation cohort were collected. Diagnostic performance of the FS and radiomics methods was compared in the validation cohort. The predictive factors for the misdiagnosis of FS were determined via univariate and multivariate analyses. RESULTS: The accuracy of radiomics method in the training and validation cohorts was 72.5 % and 68.8 % respectively. The overall accuracy of FS in the validation cohort was 70.0 %. The concordance rate between FS and final pathology when FS had a different diagnosis from radiomics classifier was significantly lower than when FS had the same diagnosis as radiomics classifier (46 vs. 87 %, P < 0.001). Univariate and Multivariate analyses showed that different diagnosis between FS and radiomics classifier was the independent predictive factor for the misdiagnosis of FS (OR: 7.46; 95%CI: 4.00-13.91; P < 0.001). CONCLUSIONS: Radiomics classifier predictions may be a reliable reference for the classification of peripheral lung adenocarcinoma manifesting as GGNs when FS cannot provide a timely diagnosis. Intraoperative diagnoses of the cases where FS had a different diagnosis from radiomics method should be considered cautiously due to the higher misdiagnosis rate.

2.
Sci Rep ; 9(1): 13503, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31534160

RESUMO

Arabidopsis VIRE2-INTERACTING PROTEIN2 (VIP2) was previously described as a protein with a NOT domain, and Arabidopsis vip2 mutants are recalcitrant to Agrobacterium-mediated root transformation. Here we show that VIP2 is a transcription regulator and the C-terminal NOT2 domain of VIP2 interacts with VirE2. Interestingly, AtVIP2 overexpressor lines in Arabidopsis did not show an improvement in Agrobacterium-mediated stable root transformation, but the transcriptome analysis identified 1,634 differentially expressed genes compared to wild-type. These differentially expressed genes belonged to various functional categories such as membrane proteins, circadian rhythm, signaling, response to stimulus, regulation of plant hypersensitive response, sequence-specific DNA binding transcription factor activity and transcription regulatory region binding. In addition to regulating genes involved in Agrobacterium-mediated plant transformation, AtVIP2 overexpressor line showed differential expression of genes involved in abiotic stresses. The majority of the genes involved in abscisic acid (ABA) response pathway, containing the Abscisic Acid Responsive Element (ABRE) element within their promoters, were down-regulated in AtVIP2 overexpressor lines. Consistent with this observation, AtVIP2 overexpressor lines were more susceptible to ABA and other abiotic stresses. Based on the above findings, we hypothesize that VIP2 not only plays a role in Agrobacterium-mediated plant transformation but also acts as a general transcriptional regulator in plants.

3.
Int Immunopharmacol ; 75: 105747, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31326719

RESUMO

BACKGROUND: Synthetic thymic peptides (sTPs) are used with chemotherapy to treat non-small cell lung cancer (NSCLC). In this study, we have performed a systematic review and meta-analysis of published trials to confirm the clinical efficacy and safety of sTPs, and determine the optimal types, usages, and sTP/chemotherapy combinations to produce the desired responses. MATERIALS AND METHODS: We collected all studies regarding combined sTP therapy and chemotherapy for NSCLC from the Chinese and English databases (up to October 2018). Bias risk was evaluated for each. Data for meta-analysis was extracted using a pre-designed form. Evidence quality was rated using the Grading of Recommendations Assessment, Development and Evaluation approach. RESULTS: We included 27 randomized controlled trials containing 1925 patients, most with unclear bias risk. Combining sTPs with chemotherapy significantly increased the objective response rate [1.28, (1.13 to 1.45)], disease control rate [1.10, (1.01 to 1.18)], quality of life (QOL) [2.05, (1.62, 2.60)], and 1-year overall survival rate [1.43, (1.15 to 1.78)], with decreased risks of neutropenia, thrombocytopenia, and gastrointestinal reactions. Optimal conditions included treatment in combination with gemcitabine or navelbine and cisplatin, twice a week, with one 3-week cycle. In these conditions, thymosin α1 improved both antitumor immunity and tumor response. Most results had good robustness, and their quality ranged from moderate to very low. CONCLUSIONS: The results suggest that treatment with sTPs, especially thymosin α1, and concomitant chemotherapy is beneficial to the patient, and provide evidence for optimal treatment regimens that may increase patient QOL and survival.

4.
Phytopathology ; 109(9): 1513-1515, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31050598

RESUMO

Puccinia novopanici is an important biotrophic fungal pathogen that causes rust disease in switchgrass. Lack of genomic resources for P. novopanici has hampered the progress toward developing effective disease resistance against this pathogen. Therefore, we have sequenced the whole genome of P. novopanici and generated a framework to understand pathogenicity mechanisms and identify effectors, repeat element invasion, genome evolution, and comparative genomics among Puccinia spp. in the future. Long- and short-read sequences were generated from P. novopanici genomic DNA by PacBio and Illumina technologies, respectively, and assembled a 99.9-Mb genome. Transcripts of P. novopanici were predicted from assembled genome using MAKER and were further validated by RNAseq data. The genome sequence information of P. novopanici will be a valuable resource for researchers working on monocot rusts and plant disease resistance in general.


Assuntos
Basidiomycota , Panicum , Basidiomycota/patogenicidade , Genoma Fúngico , Genômica , Doenças das Plantas
5.
Biotechnol Biofuels ; 12: 108, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31073332

RESUMO

Background: Downregulation of genes involved in lignin biosynthesis and related biochemical pathways has been used as a strategy to improve biofuel production. Plant C1 metabolism provides the methyl units used for the methylation reactions carried out by two methyltransferases in the lignin biosynthetic pathway: caffeic acid 3-O-methyltransferase (COMT) and caffeoyl-CoA 3-O-methyltransferase (CCoAOMT). Mutations in these genes resulted in lower lignin levels and altered lignin compositions. Reduced lignin levels can also be achieved by mutations in the C1 pathway gene, folylpolyglutamate synthetase1 (FPGS1), in both monocotyledons and dicotyledons, indicating a link between the C1 and lignin biosynthetic pathways. To test if lignin content can be further reduced by combining genetic mutations in C1 metabolism and the lignin biosynthetic pathway, fpgs1ccoaomt1 double mutants were generated and functionally characterized. Results: Double fpgs1ccoaomt1 mutants had lower thioacidolysis lignin monomer yield and acetyl bromide lignin content than the ccoaomt1 or fpgs1 mutants and the plants themselves displayed no obvious long-term negative growth phenotypes. Moreover, extracts from the double mutants had dramatically improved enzymatic polysaccharide hydrolysis efficiencies than the single mutants: 15.1% and 20.7% higher than ccoaomt1 and fpgs1, respectively. The reduced lignin and improved sugar release of fpgs1ccoaomt1 was coupled with changes in cell-wall composition, metabolite profiles, and changes in expression of genes involved in cell-wall and lignin biosynthesis. Conclusion: Our observations demonstrate that additional reduction in lignin content and improved sugar release can be achieved by simultaneous downregulation of a gene in the C1 (FPGS1) and lignin biosynthetic (CCOAOMT) pathways. These improvements in sugar accessibility were achieved without introducing unwanted long-term plant growth and developmental defects.

6.
Metabolomics ; 15(6): 85, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31144047

RESUMO

INTRODUCTION: Triterpene saponins are important bioactive plant natural products found in many plant families including the Leguminosae. OBJECTIVES: We characterize two Medicago truncatula cytochrome P450 enzymes, MtCYP72A67 and MtCYP72A68, involved in saponin biosynthesis including both in vitro and in planta evidence. METHODS: UHPLC-(-)ESI-QToF-MS was used to profile saponin accumulation across a collection of 106 M. truncatula ecotypes. The profiling results identified numerous ecotypes with high and low saponin accumulation in root and aerial tissues. Four ecotypes with significant differential saponin content in the root and/or aerial tissues were selected, and correlated gene expression profiling was performed. RESULTS: Correlation analyses between gene expression and saponin accumulation revealed high correlations between saponin content with gene expression of ß-amyrin synthase, MtCYP716A12, and two cytochromes P450 genes, MtCYP72A67 and MtCYP72A68. In vivo and in vitro biochemical assays using yeast microsomes containing MtCYP72A67 revealed hydroxylase activity for carbon 2 of oleanolic acid and hederagenin. This finding was supported by functional characterization of MtCYP72A67 using RNAi-mediated gene silencing in M. truncatula hairy roots, which revealed a significant reduction of 2ß-hydroxylated sapogenins. In vivo and in vitro assays with MtCYP72A68 produced in yeast showed multifunctional oxidase activity for carbon 23 of oleanolic acid and hederagenin. These findings were supported by overexpression of MtCYP72A68 in M. truncatula hairy roots, which revealed significant increases of oleanolic acid, 2ß-hydroxyoleanolic acid, hederagenin and total saponin levels. CONCLUSIONS: The cumulative data support that MtCYP72A68 is a multisubstrate, multifunctional oxidase and MtCYP72A67 is a 2ß-hydroxylase, both of which function during the early steps of triterpene-oleanate sapogenin biosynthesis.

7.
Sci Rep ; 9(1): 5323, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30926888

RESUMO

To evaluate the effect of glandular differentiation (GD) on tumor recurrence and progression of pT1 bladder urothelial carcinoma (UC). We performed a retrospective analysis of 82 bladder urothelial carcinoma with glandular differentiation (UCGD) patients which was pathologically diagnosed as pT1, 166 patients of pT1 UC of bladder without histologic variants served as controls. Patients of UCGD were more likely to have higher recurrence (P = 0.002) rate and higher progression rate (P < 0.001). Moreover, UCGD and a poor 5 -year overall survival (OS) (P = 0.02) while there was no difference in cancer-specific survival (CSS) (P = 0.062) between two groups. According to univariate analysis, largest tumor size (HR 1.502, CI 1.158-1.861, P = 0.029), UCGD (HR 1.787, CI 1.298-2.552, P = 0.001), lymphovascular invasion (LVI) (HR 1.226, CI 1.013-1.945, P = 0.039). UCGD (HR 1.367, CI 1.115-1.853, P = 0.038) and LVI (HR 1.416, CI 1.120-2.254, P = 0.013) were prognostic factors associated with disease recurrence and progression, respectively. Additionally, Additionally, UCGD significantly influence disease recurrence (HR 1.871, CI 1.338-2.589, P < 0.001) and progression (HR 1.462, CI 1.138-2.393, p = 0.007). Similarly, LVI significantly influence disease recurrence (HR 1.356, CI 1.053-2.174, P = 0.042) and progression (HR 1.348, CI 1.052-1.944, p = 0.022) in multivariate analysis. UCGD is significantly associated with higher recurrence and progression rate in patients with newly diagnosed pT1. Recurrent cases should be performed radical cystectomy (RC) earlier.

8.
New Phytol ; 222(3): 1610-1623, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30688366

RESUMO

The aging pathway in flowering regulation is controlled mainly by microRNA156 (miR156). Studies in Arabidopsis thaliana reveal that nine miR156-targeted SQUAMOSA PROMOTER BINDING-LIKE (SPL) genes are involved in the control of flowering. However, the roles of SPLs in flowering remain elusive in grasses. Inflorescence development in switchgrass was characterized using scanning electron microscopy (SEM). Microarray, quantitative reverse transcription polymerase chain reaction (qRT-PCR), chromatin immunoprecipitation (ChIP)-PCR and EMSA were used to identify regulators of phase transition and flowering. Gene function was characterized by downregulation and overexpression of the target genes. Overexpression of SPL7 and SPL8 promotes flowering, whereas downregulation of individual genes moderately delays flowering. Simultaneous downregulation of SPL7/SPL8 results in extremely delayed or nonflowering plants. Furthermore, downregulation of both genes leads to a vegetative-to-reproductive reversion in the inflorescence, a phenomenon that has not been reported in any other grasses. Detailed analyses demonstrate that SPL7 and SPL8 induce phase transition and flowering in grasses by directly upregulating SEPALLATA3 (SEP3) and MADS32. Thus, the SPL7/8 pathway represents a novel regulatory mechanism in grasses that is largely different from that in Arabidopsis. Additionally, genetic modification of SPL7 and SPL8 results in much taller plants with significantly increased biomass yield and sugar release.

9.
Plant Biotechnol J ; 17(3): 580-593, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30133139

RESUMO

Cell wall recalcitrance is the major challenge to improving saccharification efficiency in converting lignocellulose into biofuels. However, information regarding the transcriptional regulation of secondary cell wall biogenesis remains poor in switchgrass (Panicum virgatum), which has been selected as a biofuel crop in the United States. In this study, we present a combination of computational and experimental approaches to develop gene regulatory networks for lignin formation in switchgrass. To screen transcription factors (TFs) involved in lignin biosynthesis, we developed a modified method to perform co-expression network analysis using 14 lignin biosynthesis genes as bait (target) genes. The switchgrass lignin co-expression network was further extended by adding 14 TFs identified in this study, and seven TFs identified in previous studies, as bait genes. Six TFs (PvMYB58/63, PvMYB42/85, PvMYB4, PvWRKY12, PvSND2 and PvSWN2) were targeted to generate overexpressing and/or down-regulated transgenic switchgrass lines. The alteration of lignin content, cell wall composition and/or plant growth in the transgenic plants supported the role of the TFs in controlling secondary wall formation. RNA-seq analysis of four of the transgenic switchgrass lines revealed downstream target genes of the secondary wall-related TFs and crosstalk with other biological pathways. In vitro transactivation assays further confirmed the regulation of specific lignin pathway genes by four of the TFs. Our meta-analysis provides a hierarchical network of TFs and their potential target genes for future manipulation of secondary cell wall formation for lignin modification in switchgrass.


Assuntos
Redes Reguladoras de Genes/genética , Genes de Plantas/genética , Lignina/biossíntese , Panicum/genética , Regulação da Expressão Gênica de Plantas/genética , Genoma de Planta/genética , Panicum/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Fatores de Transcrição/genética
10.
J Exp Bot ; 69(20): 4867-4880, 2018 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-30295903

RESUMO

Medicago flowering, like that of Arabidopsis, is promoted by vernalization and long days, but alternative mechanisms are predicted because Medicago lacks the key regulators CO and FLC. Three Medicago SOC1-like genes, including MtSOC1a, were previously implicated in flowering control, but no legume soc1 mutants with altered flowering were reported. Here, reverse transciption-quantitative PCR (RT-qPCR) indicated that the timing and magnitude of MtSOC1a expression was regulated by the flowering promoter FTa1, while in situ hybridization indicated that MtSOC1a expression increased in the shoot apical meristem during the floral transition. A Mtsoc1a mutant showed delayed flowering and short primary stems. Overexpression of MtSOC1a partially rescued the flowering of Mtsoc1a, but caused a dramatic increase in primary stem height, well before the transition to flowering. Internode cell length correlated with stem height, indicating that MtSOC1a promotes cell elongation in the primary stem. However, application of gibberellin (GA3) caused stem elongation in both the wild type and Mtsoc1a, indicating that the mutant was not defective in gibberellin responsiveness. These results indicate that MtSOC1a may function as a floral integrator gene and promotes primary stem elongation. Overall, this study suggests that apart from some conservation with the Arabidopsis flowering network, MtSOC1a has a novel role in regulating aspects of shoot architecture.


Assuntos
Flores/crescimento & desenvolvimento , Proteínas de Domínio MADS/genética , Medicago/crescimento & desenvolvimento , Medicago/genética , Proteínas de Plantas/genética , Caules de Planta/crescimento & desenvolvimento , Sequência de Aminoácidos , Arabidopsis/genética , Flores/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Domínio MADS/química , Proteínas de Domínio MADS/metabolismo , Medicago/metabolismo , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Caules de Planta/genética , Alinhamento de Sequência
11.
PLoS One ; 13(9): e0204426, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30248119

RESUMO

Switchgrass is an important bioenergy crop typically grown in marginal lands, where the plants must often deal with abiotic stresses such as drought and salt. Alamo is known to be more tolerant to both stress types than Dacotah, two ecotypes of switchgrass. Understanding of their stress response and adaptation programs can have important implications to engineering more stress tolerant plants. We present here a computational study by analyzing time-course transcriptomic data of the two ecotypes to elucidate and compare their regulatory systems in response to drought and salt stresses. A total of 1,693 genes (target genes or TGs) are found to be differentially expressed and possibly regulated by 143 transcription factors (TFs) in response to drought stress together in the two ecotypes. Similarly, 1,535 TGs regulated by 110 TFs are identified to be involved in response to salt stress. Two regulatory networks are constructed to predict their regulatory relationships. In addition, a time-dependent hidden Markov model is derived for each ecotype responding to each stress type, to provide a dynamic view of how each regulatory network changes its behavior over time. A few new insights about the response mechanisms are predicted from the regulatory networks and the time-dependent models. Comparative analyses between the network models of the two ecotypes reveal key commonalities and main differences between the two regulatory systems. Overall, our results provide new information about the complex regulatory mechanisms of switchgrass responding to drought and salt stresses.


Assuntos
Secas , Regulação da Expressão Gênica de Plantas , Panicum/metabolismo , Estresse Salino/fisiologia , Processamento Alternativo , Simulação por Computador , Ecótipo , Regulação da Expressão Gênica de Plantas/fisiologia , Cadeias de Markov , Panicum/genética , Especificidade da Espécie , Transcriptoma
12.
J Agric Food Chem ; 66(34): 9070-9079, 2018 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-30086236

RESUMO

In this study, α-galactooligosaccharides (α-GOSs) were synthesized using galactose as the substrate and α-galactosidase from Aspergillus niger as the catalyst. In the reaction, synthesized products of U1, U2, U3, and U4 were detected by high-performance liquid chromatography. By mass spectrometry, nuclear magnetic resonance, and 1-phenyl-3-methyl-5-pyrazolone derivatization, U1 was the mixture of disaccharides of α-d-Gal p-(1→1)-α-d-Gal, α-d-Gal p-(1→2)-α-d-Gal, α-d-Gal p-(1→3)-α-d-Gal, α-d-Gal p-(1→4)-α-d-Gal, U2 was identified to be α-d-Gal p-(1→6)-α-d-Gal, U3 was the mixture of galactotrisaccharides linked by one α-(1→6)-glycosidic linkage and one other α-glycosidic linkage, and U4 was identified as α-d-Gal p-(1→6)-α-d-Gal p-(1→6)-α-d-Gal. Afterward, the synthesized α-GOSs (U1, U2, U3, U4, and their mixture) as well as α-GOSs (manninotriose, stachyose, ciceritol, and verbascose) obtained from natural materials were used as subjects to evaluate their immunomodulatory effects in vitro by culturing mouse macrophage RAW264.7 cells. The results showed that α-GOS with a higher degree of polymerization had better immunomodulatory activity, while to a certain extent, α-GOS linked with α-(1→6)-galactosidic linkage showed a better immunomodulatory effect.


Assuntos
Aspergillus niger/enzimologia , Proteínas Fúngicas/química , Fatores Imunológicos/química , Fatores Imunológicos/farmacologia , Oligossacarídeos/química , Oligossacarídeos/farmacologia , beta-Galactosidase/química , Animais , Aspergillus niger/genética , Biocatálise , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Galactose/química , Galactose/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Camundongos , Células RAW 264.7 , Relação Estrutura-Atividade , Especificidade por Substrato , beta-Galactosidase/genética , beta-Galactosidase/metabolismo
13.
Biotechnol Biofuels ; 11: 170, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29951114

RESUMO

Background: Switchgrass (Panicum virgatum L.) is an important bioenergy crop widely used for lignocellulosic research. While extensive transcriptomic analyses have been conducted on this species using short read-based sequencing techniques, very little has been reliably derived regarding alternatively spliced (AS) transcripts. Results: We present an analysis of transcriptomes of six switchgrass tissue types pooled together, sequenced using Pacific Biosciences (PacBio) single-molecular long-read technology. Our analysis identified 105,419 unique transcripts covering 43,570 known genes and 8795 previously unknown genes. 45,168 are novel transcripts of known genes. A total of 60,096 AS transcripts are identified, 45,628 being novel. We have also predicted 1549 transcripts of genes involved in cell wall construction and remodeling, 639 being novel transcripts of known cell wall genes. Most of the predicted transcripts are validated against Illumina-based short reads. Specifically, 96% of the splice junction sites in all the unique transcripts are validated by at least five Illumina reads. Comparisons between genes derived from our identified transcripts and the current genome annotation revealed that among the gene set predicted by both analyses, 16,640 have different exon-intron structures. Conclusions: Overall, substantial amount of new information is derived from the PacBio RNA data regarding both the transcriptome and the genome of switchgrass.

14.
Plant J ; 93(5): 894-904, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29315949

RESUMO

Phosphite (Phi) is used commercially to manage diseases mainly caused by oomycetes, primarily due to its low cost compared with other fungicides and its persistent control of oomycetous pathogens. We explored the use of Phi in controlling the fungal pathogens Puccinia emaculata and Phakopsora pachyrhizi, the causal agents of switchgrass rust and Asian soybean rust, respectively. Phi primes host defenses and efficiently inhibits the growth of P. emaculata, P. pachyrhizi and several other fungal pathogens tested. To understand these Phi-mediated effects, a detailed molecular analysis was undertaken in both the host and the pathogen. Transcriptomic studies in switchgrass revealed that Phi activates plant defense signaling as early as 1 h after application by increasing the expression of several cytoplasmic and membrane receptor-like kinases and defense-related genes within 24 h of application. Unlike in oomycetes, RNA sequencing of P. emaculata and P. pachyrhizi did not exhibit Phi-mediated retardation of cell wall biosynthesis. The genes with reduced expression in either or both rust fungi belonged to functional categories such as ribosomal protein, actin, RNA-dependent RNA polymerase, and aldehyde dehydrogenase. A few P. emaculata genes that had reduced expression upon Phi treatment were further characterized. Application of double-stranded RNAs specific to P. emaculata genes encoding glutamate N-acetyltransferase and cystathionine gamma-synthase to switchgrass leaves resulted in reduced disease severity upon P. emaculata inoculation, suggesting their role in pathogen survival and/or pathogenesis.


Assuntos
Basidiomycota/efeitos dos fármacos , Basidiomycota/genética , Panicum/microbiologia , Fosfitos/farmacologia , Doenças das Plantas/microbiologia , Basidiomycota/patogenicidade , Resistência à Doença , Proteínas Fúngicas/genética , Perfilação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Panicum/efeitos dos fármacos , Panicum/metabolismo , Phakopsora pachyrhizi/efeitos dos fármacos , Phakopsora pachyrhizi/genética , Phakopsora pachyrhizi/patogenicidade , Folhas de Planta/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Soja/efeitos dos fármacos , Soja/metabolismo , Soja/microbiologia
15.
Development ; 145(3)2018 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-29361570

RESUMO

Development of inflorescence architecture is controlled by genetic regulatory networks. TERMINAL FLOWER1 (TFL1), APETALA1 (AP1), LEAFY (LFY) and FRUITFULL (FUL) are core regulators for inflorescence development. To understand the regulation of compound inflorescence development, we characterized mutants of corresponding orthologous genes, MtTFL1, MtAP1, SINGLE LEAFLET1 (SGL1) and MtFULc, in Medicago truncatula, and analyzed expression patterns of these genes. Results indicate that MtTFL1, MtFULc, MtAP1 and SGL1 play specific roles in identity determination of primary inflorescence meristems, secondary inflorescence meristems, floral meristems and common primordia, respectively. Double mutation of MtTFL1 and MtFULc transforms compound inflorescences to simple flowers, whereas single mutation of MtTFL1 changes the inflorescence branching pattern from monopodial to sympodial. Double mutant mtap1sgl1 completely loses floral meristem identity. We conclude that inflorescence architecture in M. truncatula is controlled by spatiotemporal expression of MtTFL1, MtFULc, MtAP1 and SGL1 through reciprocal repression. Although this regulatory network shares similarity with the pea model, it has specificity in regulating inflorescence architecture in Mtruncatula This study establishes M. truncatula as an excellent genetic model for understanding compound inflorescence development in related legume crops.


Assuntos
Inflorescência/crescimento & desenvolvimento , Inflorescência/genética , Medicago truncatula/crescimento & desenvolvimento , Medicago truncatula/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Inflorescência/metabolismo , Medicago truncatula/metabolismo , Meristema/genética , Meristema/crescimento & desenvolvimento , Meristema/metabolismo , Microscopia Eletrônica de Varredura , Modelos Genéticos , Mutação , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , RNA de Plantas/genética , RNA de Plantas/metabolismo
16.
Plant Biotechnol J ; 16(4): 951-962, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28941083

RESUMO

Biomass yield, salt tolerance and drought tolerance are important targets for alfalfa (Medicago sativa L.) improvement. Medicago truncatula has been developed into a model plant for alfalfa and other legumes. By screening a Tnt1 retrotransposon-tagged M. truncatula mutant population, we identified three mutants with enhanced branching. Branch development determines shoot architecture which affects important plant functions such as light acquisition, resource use and ultimately impacts biomass production. Molecular analyses revealed that the mutations were caused by Tnt1 insertions in the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 8 (SPL8) gene. The M. truncatula spl8 mutants had increased biomass yield, while overexpression of SPL8 in M. truncatula suppressed branching and reduced biomass yield. Scanning electron microscopy (SEM) analysis showed that SPL8 inhibited branching by directly suppressing axillary bud formation. Based on the M. truncatula SPL8 sequence, alfalfa SPL8 (MsSPL8) was cloned and transgenic alfalfa plants were produced. MsSPL8 down-regulated or up-regulated alfalfa plants exhibited similar phenotypes to the M. truncatula mutants or overexpression lines, respectively. Specifically, the MsSPL8 down-regulated alfalfa plants showed up to 43% increase in biomass yield in the first harvest. The impact was even more prominent in the second harvest, with up to 86% increase in biomass production compared to the control. Furthermore, down-regulation of MsSPL8 led to enhanced salt and drought tolerance in transgenic alfalfa. Results from this research offer a valuable approach to simultaneously improve biomass production and abiotic stress tolerance in legumes.


Assuntos
Medicago sativa/genética , Medicago truncatula/genética , Proteínas de Plantas/genética , Estresse Fisiológico/genética , Biomassa , Secas , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Medicago sativa/crescimento & desenvolvimento , Medicago sativa/fisiologia , Mutação , Proteínas de Plantas/metabolismo , Brotos de Planta/genética , Brotos de Planta/fisiologia , Plantas Geneticamente Modificadas , Tolerância ao Sal/genética
17.
Biotechnol Biofuels ; 10: 255, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29213314

RESUMO

Background: Genetic engineering has been effective in altering cell walls for biofuel production in the bioenergy crop, switchgrass (Panicum virgatum). However, regulatory issues arising from gene flow may prevent commercialization of engineered switchgrass in the eastern United States where the species is native. Depending on its expression level, microRNA156 (miR156) can reduce, delay, or eliminate flowering, which may serve to decrease transgene flow. In this unique field study of transgenic switchgrass that was permitted to flower, two low (T14 and T35) and two medium (T27 and T37) miR156-overexpressing 'Alamo' lines with the transgene under the control of the constitutive maize (Zea mays) ubiquitin 1 promoter, along with nontransgenic control plants, were grown in eastern Tennessee over two seasons. Results: miR156 expression was positively associated with decreased and delayed flowering in switchgrass. Line T27 did not flower during the 2-year study. Line T37 did flower, but not all plants produced panicles. Flowering was delayed in T37, resulting in 70.6% fewer flowers than controls during the second field year with commensurate decreased seed yield: 1205 seeds per plant vs. 18,539 produced by each control. These results are notable given that line T37 produced equivalent vegetative aboveground biomass to the controls. miR156 transcript abundance of field-grown plants was congruent with greenhouse results. The five miR156 SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) target genes had suppressed expression in one or more of the transgenic lines. Line T27, which had the highest miR156 overexpression, showed significant downregulation for all five SPL genes. On the contrary, line T35 had the lowest miR156 overexpression and had no significant change in any of the five SPL genes. Conclusions: Because of the research field's geographical features, this study was the first instance of any genetically engineered trait in switchgrass, in which experimental plants were allowed to flower in the field in the eastern U.S.; USDA-APHIS-BRS regulators allowed open flowering. We found that medium overexpression of miR156, e.g., line T37, resulted in delayed and reduced flowering accompanied by high biomass production. We propose that induced miR156 expression could be further developed as a transgenic switchgrass bioconfinement tool to enable eventual commercialization.

18.
New Phytol ; 216(3): 829-840, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28877340

RESUMO

Grasses possess basal and aerial axillary buds. Previous studies have largely focused on basal bud (tiller) formation but scarcely touched on aerial buds, which may lead to aerial branch development. Genotypes with and without aerial buds were identified in switchgrass (Panicum virgatum), a dedicated bioenergy crop. Bud development was characterized using scanning electron microscopy. Microarray, RNA-seq and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were used to identify regulators of bud formation. Gene function was characterized by down-regulation and overexpression. Overexpression of miR156 induced aerial bud formation in switchgrass. Various analyses revealed that SQUAMOSA PROMOTER BINDING PROTEIN LIKE4 (SPL4), one of the miR156 targets, directly regulated aerial axillary bud initiation. Down-regulation of SPL4 promoted aerial bud formation and increased basal buds, while overexpression of SPL4 seriously suppressed bud formation and tillering. RNA-seq and RT-qPCR identified potential downstream genes of SPL4. Unlike all previously reported genes acting as activators of basal bud initiation, SPL4 acts as a suppressor for the formation of both aerial and basal buds. The miR156-SPL4 module predominantly regulates aerial bud initiation and partially controls basal bud formation. Genetic manipulation of SPL4 led to altered plant architecture with increased branching, enhanced regrowth after cutting and improved biomass yield.


Assuntos
MicroRNAs/genética , Panicum/genética , Componentes Aéreos da Planta/fisiologia , Proteínas de Plantas/genética , Brotos de Planta/genética , Técnicas de Cultura de Células , Regulação para Baixo , Regulação da Expressão Gênica de Plantas , Panicum/fisiologia , Componentes Aéreos da Planta/genética , Proteínas de Plantas/metabolismo , Brotos de Planta/crescimento & desenvolvimento , Plantas Geneticamente Modificadas , Análise de Sequência de RNA
19.
Sci Rep ; 7(1): 9260, 2017 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-28835689

RESUMO

Plant defense responses at stomata and apoplast are the most important early events during plant-bacteria interactions. The key components for the signaling of stomatal defense and nonhost resistance have not been fully characterized. Here we report the newly identified small GTPase, Nucleolar GTP-binding protein 1 (NOG1), functions for plant immunity against bacterial pathogens. Virus-induced gene silencing of NOG1 compromised nonhost resistance in N. benthamiana and tomato. Comparative genomic analysis showed that two NOG1 copies are present in all known plant species: NOG1-1 and NOG1-2. Gene downregulation and overexpression studies of NOG1-1 and NOG1-2 in Arabidopsis revealed the novel function of these genes in nonhost resistance and stomatal defense against bacterial pathogens, respectively. Specially, NOG1-2 regulates guard cell signaling in response to biotic and abiotic stimuli through jasmonic acid (JA)- and abscisic acid (ABA)-mediated pathways. The results here provide valuable information on the new functional role of small GTPase, NOG1, in guard cell signaling and early plant defense in response to bacterial pathogens.


Assuntos
Proteínas Monoméricas de Ligação ao GTP/metabolismo , Imunidade Vegetal , Plantas/imunologia , Plantas/metabolismo , Arabidopsis , Resistência à Doença/imunologia , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno/imunologia , Modelos Biológicos , Fenótipo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Plantas/genética , Plantas/microbiologia , Transdução de Sinais , Estresse Fisiológico , Transcriptoma
20.
PLoS Genet ; 13(3): e1006649, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28264034

RESUMO

Lignocellulosic biomass can be a significant source of renewable clean energy with continued improvement in biomass yield and bioconversion strategies. In higher plants, the leaf blade is the central energy convertor where solar energy and CO2 are assimilated to make the building blocks for biomass production. Here we report that introducing the leaf blade development regulator STENOFOLIA (STF), a WOX family transcription factor, into the biofuel crop switchgrass, significantly improves both biomass yield and sugar release. We found that STF overexpressing switchgrass plants produced approximately 2-fold more dry biomass and release approximately 1.8-fold more solubilized sugars without pretreatment compared to controls. The biomass increase was attributed mainly to increased leaf width and stem thickness, which was also consistent in STF transgenic rice and Brachypodium, and appeared to be caused by enhanced cell proliferation. STF directly binds to multiple regions in the promoters of some cytokinin oxidase/dehydrogenase (CKX) genes and represses their expression in all three transgenic grasses. This repression was accompanied by a significant increase in active cytokinin content in transgenic rice leaves, suggesting that the increase in biomass productivity and sugar release could at least in part be associated with improved cytokinin levels caused by repression of cytokinin degrading enzymes. Our study provides a new tool for improving biomass feedstock yield in bioenergy crops, and uncovers a novel mechanistic insight in the function of STF, which may also apply to other repressive WOX genes that are master regulators of several key plant developmental programs.


Assuntos
Citocininas/genética , Medicago truncatula/genética , Panicum/genética , Proteínas de Plantas/genética , Fatores de Transcrição/genética , Biocombustíveis , Biomassa , Brachypodium/genética , Brachypodium/metabolismo , Metabolismo dos Carboidratos , Proliferação de Células , Imunoprecipitação da Cromatina , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Citocininas/metabolismo , DNA de Plantas/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Fluorescência Verde/metabolismo , Homeostase , Análise de Sequência com Séries de Oligonucleotídeos , Oryza/genética , Oryza/metabolismo , Oxirredutases/genética , Panicum/metabolismo , Fenótipo , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Fatores de Transcrição/metabolismo , Transgenes
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