Enhancing Xanthine Dehydrogenase Activity is an Effective Way to Delay Leaf Senescence and Increase Rice Yield

2020 ◽  
Author(s):  
Ruicai Han ◽  
Xunfeng He ◽  
Xiaohua Pan ◽  
Qinghua Shi ◽  
Ziming Wu
Keyword(s):  
Chlorophyll Content ◽  
Leaf Senescence ◽  
Rice Yield ◽  
Xanthine Dehydrogenase ◽  
Purine Metabolism ◽  
Wild Type ◽  
Expression Levels ◽  
Over Expression ◽  
Ageing Processes ◽  
Rice Leaves

Abstract Xanthine dehydrogenase (XDH) is an important enzyme in purine metabolism. It is involved in regulation of the normal growth and non-biological stress-induced ageing processes in plants. The present study investigated XDH’s role in regulating rice leaf senescence. We measured physical characteristics, chlorophyll content and fluorescence parameters, active oxygen metabolism, and purine metabolism in wild-type Kitaake rice ( Oryza sativa L.), an OsXDH over-expression transgenic line ( OE9 ), and an OsXDH RNA interference line ( Ri3 ) during different growth stages. The expression patterns of the OsXDH gene confirmed that XDH was involved in the regulation of normal and abiotic stress-induced ageing processes in rice. There was no significant difference between the phenotypes of transgenic lines and wild type at the seedling stage, but differences were observed at the full heading and maturation stages. The OE9 plants were taller, with higher chlorophyll content, and their photosystems had stronger light energy absorption, transmission, dissipation, and distribution capacity, which ultimately improved the seed setting rate and 1000-seed weight. The opposite effect was found in the Ri3 plants. The OE9 line had a strong ability to remove reactive oxygen species, with increased accumulation of allantoin and alantoate. Experimental spraying of allantoin on leaves showed that it could alleviate chlorophyll degradation and decrease the content of H 2 O 2 and malonaldehyde (MDA) in rice leaves after the full heading stage. The urate oxidase gene ( UO ) expression levels in the interference line were significantly lower than those in the over-expression line and wild-type lines. The allantoinase ( ALN ) and allantoate amidinohydrolase ( AAH ) genes had significantly higher expression in the Ri3 plants than the in OE9 or wild-type plants, with OE9 plants showing the lowest levels. The senescence-related genes ACD1 , WRKY23 , WRKY53 , SGR , XERO1 , and GH27 in Ri3 plants had the highest expression levels, followed by those in the wild-type plants, with OE9 plants showing the lowest levels. These results suggest that enhanced activity of XDH can regulate the synthesis of urea-related substances, improve plant antioxidant capacity, effectively delay the ageing process in rice leaves, and increase rice yield.

scholarly journals Enhancing Xanthine Dehydrogenase Activity is an Effective Way to Delay Leaf Senescence and Increase Rice Yield

2019 ◽  
Author(s):  
Ruicai Han ◽  
Xunfeng He ◽  
Xiaohua Pan ◽  
Qinghua Shi ◽  
Ziming Wu
Keyword(s):  
Chlorophyll Content ◽  
Leaf Senescence ◽  
Rice Yield ◽  
Xanthine Dehydrogenase ◽  
Purine Metabolism ◽  
Wild Type ◽  
Expression Levels ◽  
Over Expression ◽  
Ageing Processes ◽  
Rice Leaves

Abstract Xanthine dehydrogenase (XDH) is an important enzyme in purine metabolism. It is involved in regulation of the normal growth and non-biological stress-induced ageing processes in plants. The present study investigated XDH’s role in regulating rice leaf senescence. We measured physical characteristics, chlorophyll content and fluorescence parameters, active oxygen metabolism, and purine metabolism in wild-type Kitaake rice ( Oryza sativa L.), an OsXDH over-expression transgenic line ( OE9 ), and an OsXDH RNA interference line ( Ri3 ) during different growth stages. The expression patterns of the OsXDH gene confirmed that XDH was involved in the regulation of normal and abiotic stress-induced ageing processes in rice. There was no significant difference between the phenotypes of transgenic lines and wild type at the seedling stage, but differences were observed at the full heading and maturation stages. The OE9 plants were taller, with higher chlorophyll content, and their photosystems had stronger light energy absorption, transmission, dissipation, and distribution capacity, which ultimately improved the seed setting rate and 1000-seed weight. The opposite effect was found in the Ri3 plants. The OE9 line had a strong ability to remove reactive oxygen species, with increased accumulation of allantoin and alantoate. Experimental spraying of allantoin on leaves showed that it could alleviate chlorophyll degradation and decrease the content of H 2 O 2 and malonaldehyde (MDA) in rice leaves after the full heading stage. The urate oxidase gene ( UO ) expression levels in the interference line were significantly lower than those in the over-expression line and wild-type lines. The allantoinase ( ALN ) and allantoate amidinohydrolase ( AAH ) genes had significantly higher expression in the Ri3 plants than the in OE9 or wild-type plants, with OE9 plants showing the lowest levels. The senescence-related genes ACD1 , WRKY23 , WRKY53 , SGR , XERO1 , and GH27 in Ri3 plants had the highest expression levels, followed by those in the wild-type plants, with OE9 plants showing the lowest levels. These results suggest that enhanced activity of XDH can regulate the synthesis of urea-related substances, improve plant antioxidant capacity, effectively delay the ageing process in rice leaves, and increase rice yield.

Effects of endogenous ascorbic acid on the distribution of photosynthetic electron flow in rice leaves

2019 ◽  
Vol 70 (10) ◽  
pp. 849
Author(s):  
Qilei Zhang ◽  
Minling Cai ◽  
Lina Lu ◽  
Hui Gao ◽  
Changlian Peng
Keyword(s):  
Ascorbic Acid ◽  
Photosynthetic Rate ◽  
Carbon Fixation ◽  
Higher Plants ◽  
Rice Yield ◽  
Oryza Sativa L ◽  
Electron Flow ◽  
Wild Type ◽  
Photosynthetic Electron Flow ◽  
Rice Leaves

Ascorbic acid (Asc) is one of the major antioxidants in plants. l-Galactono-1,4-lactone dehydrogenase (GLDH) is an enzyme that catalyses the last step of Asc biosynthesis in higher plants. In this study the effects of endogenous Asc on the distribution of photosynthetic electron flow were investigated in wild-type (ZH-11) rice (Oryza sativa L.) and in GLDH-overexpressing (GO-2) and GLDH-suppressed (GI-2) transgenic rice. The ratio of photosynthetic electron flow distributed to Rubisco-dependent carboxylation was highest in GO-2, whereas other electron flows in addition to carbon fixation were highest in GI-2 after flowering. Further examination showed that the photosynthetic electron flow, GLDH content and reactive oxygen species-scavenging ability were highest in GO-2 and lowest in GI-2. Therefore, the senescence of leaves was faster in GI-2 but slower in GO-2 compared with ZH-11. In addition, leaves with higher Asc content had more Rubisco content and a superior photosynthetic rate, which increased rice yield. These results suggest that increasing the endogenous Asc content of rice delays senescence, maintains a higher photosynthetic rate and results in more photosynthetic electron flow distributed to Rubisco-dependent carboxylation, ultimately leading to increased rice yield.

The Expression of Genes 5′ in the Hox-A Cluster Is Co-Ordinated Both in Normal and Leukemic Hematopoiesis.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3560-3560
Author(s):  
Ashish R. Kumar ◽  
John H. Kersey
Keyword(s):  
Bone Marrow ◽  
Time Course ◽  
Hox Genes ◽  
Bone Marrow Cells ◽  
Fusion Gene ◽  
Wild Type ◽  
Expression Levels ◽  
Over Expression ◽  
Expression Of Genes ◽  
Hoxa9 Gene

Hox genes are known to play critical roles in hematopoiesis and are probably important in the pathogenesis of leukemias. Disruption of the Hoxa9 gene in mice leads to defects in erythroid, lymphoid and myeloid hematopoiesis while over-expression of Hoxa9 leads to leukemia in mice. Transcription of Hoxa9 is partly regulated by the Mixed lineage leukemia gene (Mll) product. Bone marrow cells of mice carrying the leukemic Mll-AF9 fusion gene as a knock-in mutation (henceforth called Mll), display an increase in expression of several Hox genes - Hoxa5, Hoxa6, Hoxa7, Hoxa9 and Hoxa10, when compared to age matched wild type mice (Kumar et. al, 2004, Blood). Since the over-expressed Hox genes all belong to the same Hox-a cluster, we hypothesized that these genes might be co-regulated during normal hematopoiesis. Co-regulation of neighboring genes within the same cluster has been reported by others for the Hox-b and c clusters. To test this hypothesis for the 5′ Hox-a cluster genes, we compared expression levels of Hoxa5, Hox7 and Hoxa10 in Hoxa9 homozygous knockout (Hoxa9−/−) and wild type bone marrow by real-time quantitative RT-PCR using Taqman primers/probe sets (Applied Biosystems, CA). Expression levels of Hoxa5, Hoxa7, and Hoxa10 were all reduced by 65% ± 2% in Hoxa9−/− mice compared to wild type mice. In contrast, levels of Hoxb4 and Meis1 - homeobox genes that are not part of the Hox-a cluster - were identical in Hoxa9−/− and wild type mice. These results show no compensatory increases in expression of other 5′ Hox-a genes in the absence of Hoxa9, but instead demonstrate that disruption of Hoxa9 decreases the expression of neighboring genes in the Hox-a cluster. The hematopoietic defects seen in Hoxa9−/− mice (leucopenia, lymphopenia and blunted granulocytic response to G-CSF) might thus be attributable to the deficiency of multiple Hox-a gene products, rather than of Hoxa9 alone. To further evaluate the extent of this co-regulation, we studied the expression levels of these genes in Mll mice that lacked Hoxa9 (Hoxa9−/−/Mll-AF9+/−, henceforth called Mll/Hox). The Mll/Hox mice develop leukemia at the same rate and time course as the Mll mice, but with a phenotype that is relatively more immature. In Mll/Hox mice, the expression levels of Hoxa5 and Hoxa7 were increased 13 fold and 4 fold respectively, while those of Hoxa10 remained decreased at 35% of wild type. These results indicate that the decreased expression of neighboring Hox-a genes in Hoxa9−/− mice was reversed by Mll-AF9 for Hoxa5 and Hoxa7, but not for Hoxa10, suggesting a second level of co-regulation for Hoxa9 and Hoxa10. Overall, our findings demonstrate a co-regulated relationship between the 5′ Hox-a cluster genes during normal hematopoiesis, and provide evidence that deregulation of a single Hoxa9 gene significantly alters the expression of neighboring Hox-a cluster genes with implications for understanding the pathogenetic mechanisms of leukemia.

scholarly journals Enhancing xanthine dehydrogenase activity is an effective way to delay leaf senescence and increase rice yield

Rice ◽  
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Ruicai Han ◽  
Xunfeng He ◽  
Xiaohua Pan ◽  
Qinghua Shi ◽  
Ziming Wu
Keyword(s):  
Dehydrogenase Activity ◽  
Leaf Senescence ◽  
Rice Yield ◽  
Xanthine Dehydrogenase

scholarly journals Transcriptome Analysis Provides Insights into the Mechanism of Astaxanthin Enrichment in a Mutant of the Ridgetail White Prawn Exopalaemon carinicauda

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 618
Author(s):  
Yue Jin ◽  
Shihao Li ◽  
Yang Yu ◽  
Chengsong Zhang ◽  
Xiaojun Zhang ◽  
...  
Keyword(s):  
Transcriptome Analysis ◽  
Underlying Mechanism ◽  
Biological Processes ◽  
Wild Type ◽  
Expression Levels ◽  
In The Wild ◽  
Cuticle Proteins ◽  
Apolipoprotein D ◽  
High Level ◽  
Lower Expression

A mutant of the ridgetail white prawn, which exhibited rare orange-red body color with a higher level of free astaxanthin (ASTX) concentration than that in the wild-type prawn, was obtained in our lab. In order to understand the underlying mechanism for the existence of a high level of free astaxanthin, transcriptome analysis was performed to identify the differentially expressed genes (DEGs) between the mutant and wild-type prawns. A total of 78,224 unigenes were obtained, and 1863 were identified as DEGs, in which 902 unigenes showed higher expression levels, while 961 unigenes presented lower expression levels in the mutant in comparison with the wild-type prawns. Based on Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes analysis, as well as further investigation of annotated DEGs, we found that the biological processes related to astaxanthin binding, transport, and metabolism presented significant differences between the mutant and the wild-type prawns. Some genes related to these processes, including crustacyanin, apolipoprotein D (ApoD), cathepsin, and cuticle proteins, were identified as DEGs between the two types of prawns. These data may provide important information for us to understand the molecular mechanism of the existence of a high level of free astaxanthin in the prawn.

scholarly journals Mutations of folC cause increased susceptibility to sulfamethoxazole in Mycobacterium tuberculosis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruiqi Wang ◽  
Kun Li ◽  
Jifang Yu ◽  
Jiaoyu Deng ◽  
Yaokai Chen
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Clinical Isolates ◽  
Aminobenzoic Acid ◽  
Wild Type ◽  
Dihydropteroate Synthase ◽  
Expression Levels ◽  
Encoding Gene ◽  
Increased Susceptibility

AbstractPrevious studies showed that mutation of folC caused decreased expression of the dihydropteroate synthase encoding gene folP2 in Mycobacterium tuberculosis (M. tuberculosis). We speculated that mutation of folC in M. tuberculosis might affect the susceptibility to sulfamethoxazole (SMX). To prove this, 53 clinical isolates with folC mutations were selected and two folC mutants (I43A, I43T) were constructed based on M. tuberculosis H37Ra. The results showed that 42 of the 53 clinical isolates (79.2%) and the two lab-constructed folC mutants were more sensitive to SMX. To probe the mechanism by which folC mutations make M. tuberculosis more sensitive to SMX, folP2 was deleted in H37Ra, and expression levels of folP2 were compared between H37Ra and the two folC mutants. Although deletion of folP2 resulted in increased susceptibility to SMX, no difference in folP2 expression was observed. Furthermore, production levels of para-aminobenzoic acid (pABA) were compared between the folC mutants and the wild-type strain, and results showed that folC mutation resulted in decreased production of pABA. Taken together, we show that folC mutation leads to decreased production of pABA in M. tuberculosis and thus affects its susceptibility to SMX, which broadens our understanding of mechanisms of susceptibilities to antifolates in this bacterium.

scholarly journals INTRACISTRONIC MAPPING OF ELECTROPHORETIC SITES IN DROSOPHILA MELANOGASTER: FIDELITY OF INFORMATION TRANSFER BY GENE CONVERSION

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 289-299
Author(s):  
Margaret McCarron ◽  
William Gelbart ◽  
Arthur Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Information Transfer ◽  
Large Scale ◽  
Genetic Basis ◽  
Xanthine Dehydrogenase ◽  
Specific Protein ◽  
Wild Type ◽  
Electrophoretic Variation ◽  
The Stability ◽  
Recombination Experiments

ABSTRACT A convenient method is described for the intracistronic mapping of genetic sites responsible for electrophoretic variation of a specific protein in Drosophila melanogaster. A number of wild-type isoalleles of the rosy locus have been isolated which are associated with the production of electrophoretically distinguishable xanthine dehydrogenases. Large-scale recombination experiments were carried out involving null enzyme mutants induced on electrophoretically distinct wild-type isoalleles, the genetic basis for which is followed as a nonselective marker in the cross. Additionally, a large-scale recombination experiment was carried out involving null enzyme rosy mutants induced on the same wild-type isoallele. Examination of the electrophoretic character of crossover and convertant products recovered from the latter experiment revealed that all exhibited the same parental electrophoretic character. In addition to documenting the stability of the xanthine dehydrogenase electrophoretic character, this observation argues against a special mutagenesis hypothesis to explain conversions resulting from allele recombination studies.

scholarly journals Ectopic Overexpression of Histone H3K4 Methyltransferase CsSDG36 from Tea Plant Decreases Hyperosmotic Stress Tolerance in Arabidopsis thaliana

2021 ◽  
Vol 22 (10) ◽  
pp. 5064
Author(s):  
Qinghua Chen ◽  
Linghui Guo ◽  
Yanwen Yuan ◽  
Shuangling Hu ◽  
Fei Guo ◽  
...  
Keyword(s):  
Drought Stress ◽  
Transmembrane Domain ◽  
Tea Plant ◽  
Microtubule Assembly ◽  
Pcr Analysis ◽  
Drought Response ◽  
Stomatal Development ◽  
Wild Type ◽  
Over Expression ◽  
Histone H3k4

Histone methylation plays an important regulatory role in the drought response of many plants, but its regulatory mechanism in the drought response of the tea plant remains poorly understood. Here, drought stress was shown to induce lower relative water content and significantly downregulate the methylations of histone H3K4 in the tea plant. Based on our previous analysis of the SET Domain Group (SDG) gene family, the full-length coding sequence (CDS) of CsSDG36 was cloned from the tea cultivar ‘Fuding Dabaicha’. Bioinformatics analysis showed that the open reading frame (ORF) of the CsSDG36 gene was 3138 bp, encoding 1045 amino acids and containing the conserved structural domains of PWWP, PHD, SET and PostSET. The CsSDG36 protein showed a close relationship to AtATX4 of the TRX subfamily, with a molecular weight of 118,249.89 Da, and a theoretical isoelectric point of 8.87, belonging to a hydrophilic protein without a transmembrane domain, probably located on the nucleus. The expression of CsSDG36 was not detected in the wild type, while it was clearly detected in the over-expression lines of Arabidopsis. Compared with the wild type, the over-expression lines exhibited lower hyperosmotic resistance by accelerating plant water loss, increasing reactive oxygen species (ROS) pressure, and increasing leaf stomatal density. RNA-seq analysis suggested that the CsSDG36 overexpression caused the differential expression of genes related to chromatin assembly, microtubule assembly, and leaf stomatal development pathways. qRT-PCR analysis revealed the significant down-regulation of stomatal development-related genes (BASL, SBT1.2(SDD1), EPF2, TCX3, CHAL, TMM, SPCH, ERL1, and EPFL9) in the overexpression lines. This study provides a novel sight on the function of histone methyltransferase CsSDG36 under drought stress.

scholarly journals Directed Evolution of AraC for Improved Compatibility of Arabinose- and Lactose-Inducible Promoters

2007 ◽  
Vol 73 (18) ◽  
pp. 5711-5715 ◽  
Author(s):  
Sung Kuk Lee ◽  
Howard H. Chou ◽  
Brian F. Pfleger ◽  
Jack D. Newman ◽  
Yasuo Yoshikuni ◽  
...  
Keyword(s):  
Directed Evolution ◽  
Cross Talk ◽  
Biological Systems ◽  
Wild Type ◽  
Dimerization Domain ◽  
Expression Levels ◽  
Inducible Promoters ◽  
C Terminus ◽  
Increased Sensitivity ◽  
Better Than

ABSTRACT Synthetic biological systems often require multiple, independently inducible promoters in order to control the expression levels of several genes; however, cross talk between the promoters limits this ability. Here, we demonstrate the directed evolution of AraC to construct an arabinose-inducible (PBAD) system that is more compatible with IPTG (isopropyl-β-d-1-thiogalactopyranoside) induction of a lactose-inducible (Plac) system. The constructed system is 10 times more sensitive to arabinose and tolerates IPTG significantly better than the wild type. Detailed studies indicate that the AraC dimerization domain and C terminus are important for the increased sensitivity of AraC to arabinose.

Identification of Arabidopsis stay-green mutants with a functional ethylene-response pathway

2010 ◽  
Vol 14 ◽  
pp. 119-129
Author(s):  
R. Shirzadian-Khorramabad ◽  
H.C. Jing ◽  
J. Hille ◽  
P.P. Dijkwel
Keyword(s):  
Shelf Life ◽  
Leaf Senescence ◽  
Plant Hormone ◽  
Floral Induction ◽  
Growth Conditions ◽  
Pleiotropic Effects ◽  
Wild Type ◽  
Stay Green ◽  
Ethylene Response ◽  
Determinant Factor

Natural or harvest-induced senescence is a major determinant factor causing crop losses. The plant hormone ethylene is a strong inducer of senescence and decreasing the ethylene response can reduce senescence, albeit often with undesirable pleiotropic effects. We took advantage of ethylene-induced leaf senescence as a tool to screen for late senescence Arabidopsis mutants that still have a functional ethylenesignalling pathway. Sixteen Arabidopsis onset of leaf death (old) mutants were selected that stayed green after treatment with ethylene. While all the mutants responded to ethylene in a triple response assay, ten mutants responded to the treatment in the same way as the wild type. These ten mutants showed limited pleiotropic effects when grown under standard growth conditions but nine mutants flowered slightly later than the wild type. Genetic characterisation of a subset of the mutants identified several independent loci controlling the leaf senescence process. The approach resulted in the isolation of several stay-green mutants with a functional ethylene response pathway. The late senescence mutants show extended leaf longevity and further research may advance the field of pre- or post-harvest senescence technology. The results, moreover, suggest that there is a correlation between senescence and floral induction. Keywords: Senescence, Arabidopsis, ethylene, mutant, shelf life

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