The Rice G Protein γ Subunit DEP1/qPE9–1 Positively Regulates Grain-Filling Process by Increasing Auxin and Cytokinin Content in Rice Grains

AbstractHeterotrimeric G protein-mediated signal transduction is one of the most important and highly conserved signaling pathways in eukaryotes, which involves in the regulation of many important biological processes. As compared with those in mammals and Arabidopsis thaliana, the functions of rice heterotrimeric G protein and their molecular mechanisms are largely unknown. The rice genome contains a single Gα (RGA1) and Gβ (RGB1), and five Gγ (RGG1, RGG2, GS3, DEP1/qPE9–1, and GGC2) subunits. Recent genetic studies have shown that DEP1/qPE9–1, an atypical putative Gγ protein, is responsible for the grain size as well as the dense and erect panicles, but the biochemical and molecular mechanisms underlying the control of grain size are not well understood. Here, we report that rice plants carrying DEP1/qPE9–1 have more endosperm cells per grain than plants contain the dep1/qpe9–1 allele. The DEP1/qPE9–1 line has a higher rate and more prolonged period of starch accumulation than the dep1/qpe9–1 line. Additionally, the expression of several essential genes encoding enzymes catalyzing sucrose metabolism and starch biosynthesis is higher in the DEP1/qPE9–1 line than in the dep1/qpe9–1 line, especially from the mid to late grain-filling stage. Grains of the DEP1/qPE9–1 line also have higher contents of three phytohormones, ABA, auxin and cytokinin. Exogenous application of auxin or cytokinin enhanced the starch accumulation and the expression of genes encoding grain-filling-related enzymes in the grains of dep1/qpe9–1, whereas ABA produced no effects. Based on these results, we conclude that DEP1/qPE9–1 positively regulates starch accumulation primarily through auxin and cytokinin, which enhance the expression of genes encoding starch biosynthesis during the mid to late grain-filling stage, resulting in increased duration of the grain-filling process.

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The rice G protein γ subunit qPE9-1 positively regulates grain-filling process by interacting with abscisic acid and auxin

10.1101/487850 ◽

2018 ◽

Author(s):

Dongping Zhang ◽

Minyan Zhang ◽

Yong Zhou ◽

Yuzhu Wang ◽

Hongyingxue Chen ◽

...

Keyword(s):

Molecular Mechanisms ◽

Rice Genome ◽

Grain Filling ◽

Starch Biosynthesis ◽

Starch Accumulation ◽

Genetic Studies ◽

Filling Stage ◽

Expression Of Genes ◽

Genes Encoding ◽

Grain Filling Stage

The rice genome contains a single Gα (RGA1) and Gβ (RGB1) and five Gγ subunits. Recent genetic studies have shown that DEP1/qPE9-1, an atypical putative Gγ protein, is responsible for dense and erect panicles, but the biochemical and molecular mechanisms underlying control of grain size are not well understood. Here, we report that plants carrying qPE9-1 have more endosperm cells per grain than plants contain the qpe9-1 allele. The qPE9-1 line has a higher rate and longer period of starch accumulation than the qpe9-1 line. Additionally, the expression of several key genes encoding enzymes catalyzing sucrose metabolism and starch biosynthesis is higher in the qPE9-1 line than in the qpe9-1 line, especially from the mid to late grain-filling stage. Grains of the qPE9-1 line also have higher contents of two phytohormones, ABA and IAA. Exogenous application of ABA or IAA enhanced starch accumulation and the expression of genes encoding grain-filling-related enzymes in the grains of qPE9-1, whereas only IAA produced these effects in qpe9-1. Based on these results, we conclude that qPE9-1 promotes endosperm cell proliferation and positively regulates starch accumulation largely through ABA and IAA, which enhance the expression of genes encoding starch biosynthesis during the late grain-filling stage.

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RGB1 Regulates Grain Development and Starch Accumulation Through Its Effect on OsYUC11-Mediated Auxin Biosynthesis in Rice Endosperm Cells

Frontiers in Plant Science ◽

10.3389/fpls.2021.585174 ◽

2021 ◽

Vol 12 ◽

Author(s):

Dongping Zhang ◽

Minyan Zhang ◽

Jiansheng Liang

Keyword(s):

Grain Size ◽

G Protein ◽

Grain Filling ◽

Auxin Biosynthesis ◽

Starch Accumulation ◽

Grain Development ◽

Filling Process ◽

Filling Stage ◽

Grain Filling Stage ◽

Lower Expression

RGB1, a subunit of heterotrimeric G protein, plays important roles in regulating grain size and weight of rice. However, the molecular mechanisms underlying controlling grain filling process by G protein are still largely unclear. In the present study, we show that RGB1 controls not only the grain size but also the grain filling process. Knock-down of RGB1 significantly delayed grain development and reduced starch accumulation and grain weight, which was closely related to the delayed and the lower expression of genes encoding sucrose metabolism and starch biosynthesis related enzymes during grain filling stage. Suppression of RGB1 expression also resulted in the lower auxin content in grains, which was correlated with the lower expression of OsNF-YB1 and OsYUC11 during grain filling stage. Further biochemical evidence showed that OsYUC11 expression was under control of OsNF-YB1 by its interaction with promoter of OsYUC11. Taken together, we propose that RGB1 controls rice grain development and grain filling process by changing auxin homeostasis in endosperm cells. OsNF-YB1, which acts as a key downstream effector of RGB1, interacts directly with the promoter of OsYUC11 and stimulates the OsYUC11 expression, thereby regulating auxin biosynthesis and starch accumulation and grain size.

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The Rho-family GTPase OsRac1 controls rice grain size and yield by regulating cell division

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1902321116 ◽

2019 ◽

Vol 116 (32) ◽

pp. 16121-16126 ◽

Cited By ~ 5

Author(s):

Ying Zhang ◽

Yan Xiong ◽

Renyi Liu ◽

Hong-Wei Xue ◽

Zhenbiao Yang

Keyword(s):

Grain Size ◽

Cell Division ◽

Grain Yield ◽

Molecular Mechanisms ◽

Grain Filling ◽

High Yield ◽

Rice Grain ◽

Rop Gtpase ◽

Key Factor ◽

Grain Width

Grain size is a key factor for determining grain yield in crops and is a target trait for both domestication and breeding, yet the mechanisms underlying the regulation of grain size are largely unclear. Here we show that the grain size and yield of rice (Oryza sativa) is positively regulated by ROP GTPase (Rho-like GTPase from plants), a versatile molecular switch modulating plant growth, development, and responses to the environment. Overexpression of rice OsRac1ROP not only increases cell numbers, resulting in a larger spikelet hull, but also accelerates grain filling rate, causing greater grain width and weight. As a result, OsRac1 overexpression improves grain yield in O. sativa by nearly 16%. In contrast, down-regulation or deletion of OsRac1 causes the opposite effects. RNA-seq and cell cycle analyses suggest that OsRac1 promotes cell division. Interestingly, OsRac1 interacts with and regulates the phosphorylation level of OsMAPK6, which is known to regulate cell division and grain size in rice. Thus, our findings suggest OsRac1 modulates rice grain size and yield by influencing cell division. This study provides insights into the molecular mechanisms underlying the control of rice grain size and suggests that OsRac1 could serve as a potential target gene for breeding high-yield crops.

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Cyclophilin a as a Mediator of Tissue Injure and Nephrotoxicity

Nephrology Research & Reviews ◽

10.4081/nr.2012.e9 ◽

2012 ◽

Vol 4 (2) ◽

pp. 42-44

Author(s):

Grace Moscoso-Solorzano ◽

Gianna Mastroianni-Kirsztajn

Keyword(s):

Molecular Mechanisms ◽

Tissue Injury ◽

Cyclophilin A ◽

Common Mechanism ◽

Ppiase Activity ◽

Expression Of Genes ◽

Inflammatory Stimuli ◽

Genes Encoding ◽

Inflammatory Processes

Cyclophilin A (CypA) belongs to the peptidyl-prolil isomerase (PPlase) family of proteins and it is also known as the cellular receptor for cyclosporine A (CsA). CsA binds to CypA and inhibits the PPIase activity, but the CypA-CsA complex also binds to calcineurin that promotes the expression of genes encoding cytokines and other proteins required for immune response. In addition, the polymorphism variation of CypA promoter seems to have an influence on the expression of CypA in in vitro studies. CypA was also implicated in inflammatory processes (such as, among others, those observed in rheumatoid arthritis, atherosclerotic disease, nephrotoxicity) and it can be secreted by cells in response to inflammatory stimuli. CypA can also have a role in the molecular mechanisms by which CsA induces nephroxicity but these remain poorly understood. Recent studies suggest that CsA inhibition of CypA PPlase activity is a possible mechanism of this drug toxicity. In addition, CypA overexpression could be protective against CsA nephrotoxicity. Finally, the putative common mechanism by which CypA could be involved in CsA nephrotoxicity and tissue injury is related to its proinflammatory effects in cells.

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3,5-T2 alters murine genes relevant for xenobiotic, steroid, and thyroid hormone metabolism

Journal of Molecular Endocrinology ◽

10.1530/jme-15-0159 ◽

2016 ◽

Vol 56 (4) ◽

pp. 311-323 ◽

Cited By ~ 19

Author(s):

Julika Lietzow ◽

Janine Golchert ◽

Georg Homuth ◽

Uwe Völker ◽

Wenke Jonas ◽

...

Keyword(s):

Thyroid Hormone ◽

Molecular Mechanisms ◽

Target Genes ◽

Phase Iii ◽

Whole Body ◽

High Dose ◽

Thyroid Hormone Metabolism ◽

Expression Of Genes ◽

Genes Encoding ◽

Novel Target

The endogenous thyroid hormone (TH) metabolite 3,5-diiodo-l-thyronine (3,5-T2) acts as a metabolically active substance affecting whole-body energy metabolism and hepatic lipid handling in a desirable manner. Considering possible adverse effects regarding thyromimetic action of 3,5-T2 treatment in rodents, the current literature remains largely controversial. To obtain further insights into molecular mechanisms and to identify novel target genes of 3,5-T2 in liver, we performed a microarray-based liver tissue transcriptome analysis of male lean and diet-induced obese euthyroid mice treated for 4 weeks with a dose of 2.5 µg/g bw 3,5-T2. Our results revealed that 3,5-T2 modulates the expression of genes encoding Phase I and Phase II enzymes as well as Phase III transporters, which play central roles in metabolism and detoxification of xenobiotics. Additionally, 3,5-T2 changes the expression of TH responsive genes, suggesting a thyromimetic action of 3,5-T2 in mouse liver. Interestingly, 3,5-T2 in obese but not in lean mice influences the expression of genes relevant for cholesterol and steroid biosynthesis, suggesting a novel role of 3,5-T2 in steroid metabolism of obese mice. We concluded that treatment with 3,5-T2 in lean and diet-induced obese male mice alters the expression of genes encoding hepatic xenobiotic-metabolizing enzymes that play a substantial role in catabolism and inactivation of xenobiotics and TH and are also involved in hepatic steroid and lipid metabolism. The administration of this high dose of 3,5-T2 might exert adverse hepatic effects. Accordingly, the conceivable use of 3,5-T2 as pharmacological hypolipidemic agent should be considered with caution.

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Temperature Stress at Grain Filling Stage Mediates Expression of Three Isoform Genes Encoding Starch Branching Enzymes in Rice Endosperm

Rice Science ◽

10.1016/s1672-6308(08)60078-5 ◽

2009 ◽

Vol 16 (3) ◽

pp. 187-193 ◽

Cited By ~ 6

Author(s):

Ke-su WEI ◽

Fang-min CHENG ◽

Qi-fang ZHANG ◽

Kui-gang LIU

Keyword(s):

Temperature Stress ◽

Grain Filling ◽

Rice Endosperm ◽

Filling Stage ◽

Starch Branching Enzymes ◽

Genes Encoding ◽

Branching Enzymes ◽

Grain Filling Stage

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Transcriptome Sequencing and Differential Expression Analysis Reveal Molecular Mechanisms for Seed Starch Accumulation in Chinese Chestnut Metaxenia

10.21203/rs.3.rs-80588/v1 ◽

2020 ◽

Author(s):

Shengxing Li ◽

Zhuogong Shi ◽

Zhiheng Zhao ◽

Qiurong Zhu ◽

Liang Tao ◽

...

Keyword(s):

Molecular Mechanisms ◽

Soluble Sugars ◽

Differential Expression Analysis ◽

Female Parent ◽

Sucrose Metabolism ◽

Starch Accumulation ◽

Seed Kernel ◽

Nutrient Contents ◽

Genes Encoding ◽

Lim Proteins

Abstract Background: Chestnut is an important kind of edible nut rich in starch and protein. The characteristics and nutrient contents of chestnut have been found to show obvious metaxenia effects in previous studies. To improve the understanding of the metaxenia effect on chestnut starch and sucrose metabolism, this study used three varieties of chestnut, ‘Yongfeng 1’, ‘Yong Renzao’ and ‘Yimeng 1’, as male parents to pollinate ‘Yongfeng 1’, as the female parent, and studied the mechanisms of starch and sucrose metabolism in three starch accumulation stages (70 (S1), 82 (S2), and 94 (S3) days after pollination , DAP) in the chestnut seed kernel.Result: Most carbohydrate metabolism genes were highly expressed in YFF in stage S2 and in YFR and YFM in stage S3. In stage S3, hub genes encoding HSF_DNA-binding, ACT, Pkinase, and LIM proteins and four transcription factors were highly expressed, with YFF showing the higest expression, followed by YFR and, finally, YFM. In addition, transcriptome analysis of the kernels at 70, 82 and 94 DAP showed that the starch granule-bound starch synthase (EC 2.4.1.242) and ADP-glucose pyrophosphorylase (EC 2.7 .7.27) genes were actively expressed at 94 DAF. Chestnut seeds regulate the accumulation of soluble sugars, reducing sugars and starch by controlling glycosyl transferase and hydrolysis activity during development.Conclusion: These studies and resources have important guiding significance for further research on starch and sucrose metabolism and other types of metabolism related to chestnut metaxenia.

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Activity of Aztreonam in Combination with Avibactam, Clavulanate, Relebactam, and Vaborbactam against Multidrug-Resistant Stenotrophomonas maltophilia

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00297-20 ◽

2020 ◽

Vol 64 (12) ◽

Cited By ~ 1

Author(s):

M. Biagi ◽

D. Lamm ◽

K. Meyer ◽

A. Vialichka ◽

M. Jurkovic ◽

...

Keyword(s):

Stenotrophomonas Maltophilia ◽

Molecular Mechanisms ◽

Efflux Pump ◽

Treatment Strategies ◽

Multidrug Resistant ◽

Content Type ◽

Expression Of Genes ◽

Genes Encoding ◽

Novel Treatment Strategies

ABSTRACT The intrinsic L1 metallo- and L2 serine-β-lactamases in Stenotrophomonas maltophilia make it naturally multidrug resistant and difficult to treat. There is a need to identify novel treatment strategies for this pathogen, especially against isolates resistant to first-line agents. Aztreonam in combination with avibactam has demonstrated potential, although data on other aztreonam–β-lactamase inhibitor (BLI) combinations are lacking. Additionally, molecular mechanisms for reduced susceptibility to these combinations have not been explored. The objectives of this study were to evaluate and compare the in vitro activities and to understand the mechanisms of resistance to aztreonam in combination with avibactam, clavulanate, relebactam, and vaborbactam against S. maltophilia. A panel of 47 clinical S. maltophilia strains nonsusceptible to levofloxacin and/or trimethoprim-sulfamethoxazole were tested against each aztreonam-BLI combination via broth microdilution, and 6 isolates were then evaluated in time-kill analyses. Three isolates with various aztreonam-BLI MICs were subjected to whole-genome sequencing and quantitative reverse transcriptase PCR. Avibactam restored aztreonam susceptibility in 98% of aztreonam-resistant isolates, compared to 61, 71, and 15% with clavulanate, relebactam, and vaborbactam, respectively. The addition of avibactam to aztreonam resulted in a ≥2-log10-CFU/ml decrease at 24 h versus aztreonam alone against 5/6 isolates compared to 1/6 with clavulanate, 4/6 with relebactam, and 2/6 with vaborbactam. Molecular analyses revealed that decreased susceptibility to aztreonam-avibactam was associated with increased expression of genes encoding L1 and L2, as well as the efflux pump (smeABC). Aztreonam-avibactam is the most promising BLI-combination against multidrug-resistant S. maltophilia. Decreased susceptibility may be due to the combination of overexpressed β-lactamases and efflux pumps. Further studies evaluating this combination against S. maltophilia are warranted.

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