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1.
Can J Microbiol ; 70(1): 15-31, 2024 Jan 01.
Article in English | MEDLINE | ID: mdl-37699259

ABSTRACT

Cold stress is an important factor limiting rice production and distribution. Identifying factors that contribute to cold tolerance in rice is of primary importance. While some plant specific genetic factors involved in cold tolerance have been identified, the role of the rice microbiome remains unexplored. In this study, we evaluated the influence of plant growth promoting bacteria (PGPB) with the ability of phosphate solubilization on rice cold tolerance and survival. To reach this goal, inoculated and uninoculated 2-week-old seedlings were cold stressed and evaluated for survival and other phenotypes such as electrolyte leakage (EL) and necessary elements for cold tolerance. The results of this study showed that of the five bacteria, Pseudomonas mosselii, improved both indica and japonica varietal plants' survival and decreased EL, indicating increased membrane integrity. We observed different possible cold tolerance mechanisms in japonica and indica plants such as increases in proline and reduced glutathione levels, respectively. This bacterium also improved the shoot growth of cold exposed indica plants during the recovery period. This study confirmed the host genotype dependent activity of P. mosselii and indicated that there is an interaction between specific plant genes and bacterial genes that causes different plant responses to cold stress.


Subject(s)
Glutathione , Oryza , Glutathione/genetics , Proline/genetics , Genotype , Cold Temperature
2.
Front Plant Sci ; 14: 1303651, 2023.
Article in English | MEDLINE | ID: mdl-38162313

ABSTRACT

Due to global climate change resulting in extreme temperature fluctuations, it becomes increasingly necessary to explore the natural genetic variation in model crops such as rice to facilitate the breeding of climate-resilient cultivars. To uncover genomic regions in rice involved in managing cold stress tolerance responses and to identify associated cold tolerance genes, two inbred line populations developed from crosses between cold-tolerant and cold-sensitive parents were used for quantitative trait locus (QTL) mapping of two traits: degree of membrane damage after 1 week of cold exposure quantified as percent electrolyte leakage (EL) and percent low-temperature seedling survivability (LTSS) after 1 week of recovery growth. This revealed four EL QTL and 12 LTSS QTL, all overlapping with larger QTL regions previously uncovered by genome-wide association study (GWAS) mapping approaches. Within the QTL regions, 25 cold-tolerant candidate genes were identified based on genomic differences between the cold-tolerant and cold-sensitive parents. Of those genes, 20% coded for receptor-like kinases potentially involved in signal transduction of cold tolerance responses; 16% coded for transcription factors or factors potentially involved in regulating cold tolerance response effector genes; and 64% coded for protein chaperons or enzymes potentially serving as cold tolerance effector proteins. Most of the 25 genes were cold temperature regulated and had deleterious nucleotide variants in the cold-sensitive parent, which might contribute to its cold-sensitive phenotype.

3.
Int J Mol Sci ; 23(19)2022 Sep 30.
Article in English | MEDLINE | ID: mdl-36232853

ABSTRACT

Stress-associated protein (SAP) genes-encoding A20/AN1 zinc-finger domain-containing proteins-play pivotal roles in regulating stress responses, growth, and development in plants. They are considered suitable candidates to improve abiotic stress tolerance in plants. However, the SAP gene family in sweetpotato (Ipomoea batatas) and its relatives is yet to be investigated. In this study, 20 SAPs in sweetpotato, and 23 and 26 SAPs in its wild diploid relatives Ipomoea triloba and Ipomoea trifida were identified. The chromosome locations, gene structures, protein physiological properties, conserved domains, and phylogenetic relationships of these SAPs were analyzed systematically. Binding motif analysis of IbSAPs indicated that hormone and stress responsive cis-acting elements were distributed in their promoters. RT-qPCR or RNA-seq data revealed that the expression patterns of IbSAP, ItbSAP, and ItfSAP genes varied in different organs and responded to salinity, drought, or ABA (abscisic acid) treatments differently. Moreover, we found that IbSAP16 driven by the 35 S promoter conferred salinity tolerance in transgenic Arabidopsis. These results provided a genome-wide characterization of SAP genes in sweetpotato and its two relatives and suggested that IbSAP16 is involved in salinity stress responses. Our research laid the groundwork for studying SAP-mediated stress response mechanisms in sweetpotato.


Subject(s)
Arabidopsis , Ipomoea batatas , Ipomoea , Abscisic Acid/metabolism , Arabidopsis/genetics , Gene Expression Regulation, Plant , Heat-Shock Proteins/metabolism , Hormones/metabolism , Ipomoea/genetics , Ipomoea batatas/genetics , Ipomoea batatas/metabolism , Phylogeny , Plant Proteins/metabolism , Plants, Genetically Modified/genetics , Salt Tolerance/genetics , Stress, Physiological/genetics , Zinc/metabolism , Zinc Fingers/genetics
4.
Microbiol Spectr ; 10(4): e0278721, 2022 08 31.
Article in English | MEDLINE | ID: mdl-35862989

ABSTRACT

Asian rice is one of the most important crops because it is a staple food for almost half of the world's population. To have production of rice keep pace with a growing world population, it is anticipated that the use of fertilizers will also need to increase, which may cause environmental damage through runoff impacts. An alternative strategy to increase crop yield is the use of plant growth-promoting bacteria. Thousands of microbial species can exist in association with plant roots and shoots, and some are critical to the plant's survival. We isolated 140 bacteria from two distantly related rice accessions and investigated whether their impact on the growth of four different rice accessions. The bacterial isolates were screened for their ability to solubilize phosphate, a known plant growth-promoting characteristic, and 25 isolates were selected for further analysis. These 25 phosphate-solubilizing isolates were also able to produce other potentially growth-promoting factors. Five of the most promising bacterial isolates were chosen for whole-genome sequencing. Four of these bacteria, isolates related to Pseudomonas mosselii, a Microvirga sp., Paenibacillus rigui, and Paenibacillus graminis, improved root and shoot growth in a rice genotype-dependent manner. This indicates that while bacteria have several known plant growth-promoting functions, their effects on growth parameters are rice genotype dependent and suggest a close relationship between plants and their microbial partners. IMPORTANCE In this study, endophytic bacterial isolates from roots and shoots of two distantly related rice accessions were characterized phenotypically and genotypically. From the isolated bacterial species, five of the most promising plant growth-promoting bacteria were selected to test their abilities to enhance growth of the four rice accessions. Interestingly, plant growth enhancement was both bacterial isolate specific and plant genotype specific. However, the positive interactions between plant and bacteria could not easily be predicted because rice growth-promoting bacteria isolated from their host plants did not necessarily stimulate growth of their own host.


Subject(s)
Oryza , Genotype , Oryza/microbiology , Phosphates , Plant Roots/microbiology
5.
Genes (Basel) ; 12(11)2021 10 26.
Article in English | MEDLINE | ID: mdl-34828305

ABSTRACT

Boosting cold stress tolerance in crop plants can minimize stress-mediated yield losses. Asian rice (Oryza sativa L.), one of the most consumed cereal crops, originated from subtropical regions and is generally sensitive to low temperature environments. Within the two subspecies of rice, JAPONICA, and INDICA, the cold tolerance potential of its accessions is highly variable and depends on their genetic background. Yet, cold stress tolerance response mechanisms are complex and not well understood. This study utilized 370 accessions from the Rice Diversity Panel 1 (RDP1) to investigate and correlate four cold stress tolerance response phenotypes: membrane damage, seedling survivability, and catalase and anthocyanin antioxidative activity. Most JAPONICA accessions, and admixed accessions within JAPONICA, had lower membrane damage, higher antioxidative activity, and overall, higher seedling survivability compared to INDICA accessions. Genome-wide association study (GWAS) mapping was done using the four traits to find novel quantitative trait loci (QTL), and to validate and fine-map previously identified QTL. A total of 20 QTL associated to two or more traits were uncovered by our study. Gene Ontology (GO) term enrichment analyses satisfying four layers of filtering retrieved three potential pathways: signal transduction, maintenance of plasma membrane and cell wall integrity, and nucleic acids metabolism as general mechanisms of cold stress tolerance responses involving antioxidant activity.


Subject(s)
Adaptation, Biological/genetics , Antioxidants/metabolism , Cold-Shock Response/genetics , Oryza/genetics , Quantitative Trait Loci , Chromosome Mapping , Chromosomes, Plant , Cold Temperature , Genome-Wide Association Study , Oryza/metabolism , Oryza/physiology , Polymorphism, Single Nucleotide , Seedlings/genetics
6.
Rice (N Y) ; 13(1): 57, 2020 Aug 14.
Article in English | MEDLINE | ID: mdl-32797316

ABSTRACT

BACKGROUND: Developing chilling tolerant accessions of domesticated Asian rice is a potential source of significant crop improvement. The uniquely chilling sensitive nature of the tropically originating Oryza sativa make it the most important cereal crop that can gain significantly from improved tolerance to low temperatures. However, mechanisms underlying this complex trait are not fully understood. Oryza sativa has two subspecies with different levels of chilling tolerance, JAPONICA and INDICA, providing an ideal tool to investigate mechanistic differences in the chilling stress tolerance responses within this important crop species. RESULTS: The Rice Diversity Panel 1 (RDP1) was used to investigate a core set of Oryza sativa accessions. The tools available for this panel allowed for a comprehensive analysis of two chilling tolerance traits at multiple temperatures across a 354-cultivar subset of the RDP1. Chilling tolerance trait values were distributed as mostly subpopulation specific clusters of Tolerant, Intermediate, and Sensitive accessions. Genome-wide association study (GWAS) mapping approaches using all 354 accessions yielded a total of 245 quantitative trait loci (QTL), containing 178 unique QTL covering 25% of the rice genome, while 40 QTL were identified by multiple traits. QTL mappings using subsets of rice accession clusters yielded another 255 QTL, for a total of 500 QTL. The genes within these multiple trait QTL were analyzed for Gene Ontology (GO) term and potential pathway enrichments. Terms related to "carbohydrate biosynthesis", "carbohydrate transmembrane transport", "small molecule protein modification", and "plasma membrane" were enriched from this list. Filtering was done to identify more likely candidate pathways involved in conferring chilling tolerance, resulting in enrichment of terms related to "Golgi apparatus", "stress response", "transmembrane transport", and "signal transduction". CONCLUSIONS: Taken together, these GO term clusters revealed a likely involvement of Golgi-mediated subcellular and extracellular vesicle and intracellular carbohydrate transport as a general cold stress tolerance response mechanism to achieve cell and metabolic homeostasis under chilling stress.

7.
J Exp Bot ; 71(9): 2723-2739, 2020 05 09.
Article in English | MEDLINE | ID: mdl-31974553

ABSTRACT

Due to its subtropical origins, rice (Oryza sativa) is sensitive to low-temperature stress. In this study, we identify LOC_Os04g24110, annotated to encode the UDP-glycosyltransferase enzyme UGT90A1, as a gene associated with the low-temperature seedling survivability (LTSS) quantitative trait locus qLTSS4-1. Differences between haplotypes in the control region of OsUGT90A1 correlate with chilling tolerance phenotypes, and reflect differential expression between tolerant and sensitive accessions rather than differences in protein sequences. Expression of OsUGT90A1 is initially enhanced by low temperature, and its overexpression helps to maintain membrane integrity during cold stress and promotes leaf growth during stress recovery, which are correlated with reduced levels of reactive oxygen species due to increased activities of antioxidant enzymes. In addition, overexpression of OsUGT90A1 in Arabidopsis improves freezing survival and tolerance to salt stress, again correlated with enhanced activities of antioxidant enzymes. Overexpression of OsUGT90A1 in rice decreases root lengths in 3-week-old seedlings while gene-knockout increases the length, indicating that its differential expression may affect phytohormone activities. We conclude that higher OsUGT90A1 expression in chilling-tolerant accessions helps to maintain cell membrane integrity as an abiotic stress-tolerance mechanism that prepares plants for the resumption of growth and development during subsequent stress recovery.


Subject(s)
Oryza , Cell Membrane , Cold Temperature , Cold-Shock Response , Gene Expression Regulation, Plant , Glycosyltransferases/genetics , Oryza/genetics , Seedlings/genetics
8.
Plant Biotechnol J ; 17(9): 1834-1849, 2019 09.
Article in English | MEDLINE | ID: mdl-30811812

ABSTRACT

Cold temperature during the reproductive stage often causes great yield loss of grain crops in subtropical and temperate regions. Previously we showed that the rice transcription factor bZIP73Jap plays an important role in cold adaptation at the seedling stage. Here we further demonstrate that bZIP73Jap also confers cold stress tolerance at the reproductive stage. bZIP73Jap was up-regulated under cold treatment and predominately expressed in panicles at the early binucleate and flowering stages. bZIP73Jap forms heterodimers with bZIP71, and co-expression of bZIP73Jap and bZIP71 transgenic lines significantly increased seed-setting rate and grain yield under natural cold stress conditions. bZIP73Jap :bZIP71 not only repressed ABA level in anthers, but also enhanced soluble sugar transport from anthers to pollens and improved pollen grain fertility, seed-setting rate, and grain yield. Interestingly, bZIP73Jap :bZIP71 also regulated the expression of qLTG3-1Nip , and qLTG3-1Nip overexpression lines greatly improved rice tolerance to cold stress during the reproductive stage. Therefore, our work establishes a framework for rice cold stress tolerance through the bZIP71-bZIP73Jap -qLTG3-1Nip -sugar transport pathway. Together with our previous work, our results provide a powerful tool for improving rice cold stress tolerance at both the seedling and the reproductive stages.


Subject(s)
Basic-Leucine Zipper Transcription Factors/genetics , Cold Temperature , Oryza/physiology , Plant Proteins/genetics , Gene Expression Regulation, Plant , Oryza/genetics , Stress, Physiological
9.
Nat Commun ; 9(1): 3302, 2018 08 17.
Article in English | MEDLINE | ID: mdl-30120236

ABSTRACT

Cold stress is a major factor limiting production and geographic distribution of rice (Oryza sativa). Although the growth range of japonica subspecies has expanded northward compared to modern wild rice (O. rufipogon), the molecular basis of the adaptation remains unclear. Here we report bZIP73, a bZIP transcription factor-coding gene with only one functional polymorphism (+511 G>A) between the two subspecies japonica and indica, may have facilitated japonica adaptation to cold climates. We show the japonica version of bZIP73 (bZIP73Jap) interacts with bZIP71 and modulates ABA levels and ROS homeostasis. Evolutionary and population genetic analyses suggest bZIP73 has undergone balancing selection; the bZIP73Jap allele has firstly selected from standing variations in wild rice and likely facilitated cold climate adaptation during initial japonica domestication, while the indica allele bZIP73Ind was subsequently selected for reasons that remain unclear. Our findings reveal early selection of bZIP73Jap may have facilitated climate adaptation of primitive rice germplasms.


Subject(s)
Adaptation, Physiological/genetics , Cold Climate , Genes, Plant , Oryza/genetics , Oryza/physiology , Plant Proteins/genetics , Selection, Genetic , Abscisic Acid/metabolism , Genetic Association Studies , Geography , Models, Genetic , Phylogeny , Plants, Genetically Modified , Polymorphism, Single Nucleotide/genetics , Protein Binding , Reactive Oxygen Species/metabolism , Stress, Physiological/genetics
10.
Front Plant Sci ; 8: 957, 2017.
Article in English | MEDLINE | ID: mdl-28642772

ABSTRACT

Rice (Oryza sativa L.) is often exposed to cool temperatures during spring planting in temperate climates. A better understanding of genetic pathways regulating chilling tolerance will enable breeders to develop varieties with improved tolerance during germination and young seedling stages. To dissect chilling tolerance, five assays were developed; one assay for the germination stage, one assay for the germination and seedling stage, and three for the seedling stage. Based on these assays, five chilling tolerance indices were calculated and assessed using 202 O. sativa accessions from the Rice Mini-Core (RMC) collection. Significant differences between RMC accessions made the five indices suitable for genome-wide association study (GWAS) based quantitative trait loci (QTL) mapping. For young seedling stage indices, japonica and indica subspecies clustered into chilling tolerant and chilling sensitive accessions, respectively, while both subspecies had similar low temperature germinability distributions. Indica subspecies were shown to have chilling acclimation potential. GWAS mapping uncovered 48 QTL at 39 chromosome regions distributed across all 12 rice chromosomes. Interestingly, there was no overlap between the germination and seedling stage QTL. Also, 18 QTL and 32 QTL were in regions discovered in previously reported bi-parental and GWAS based QTL mapping studies, respectively. Two novel low temperature seedling survivability (LTSS)-QTL, qLTSS3-4 and qLTSS4-1, were not in a previously reported QTL region. QTL with strong effect alleles identified in this study will be useful for marker assisted breeding efforts to improve chilling tolerance in rice cultivars and enhance gene discovery for chilling tolerance.

11.
Nat Commun ; 6: 7658, 2015 Jul 23.
Article in English | MEDLINE | ID: mdl-26203923

ABSTRACT

Priming is a major mechanism behind the immunological 'memory' observed during two key plant systemic defences: systemic acquired resistance (SAR) and induced systemic resistance (ISR). Lipid-derived azelaic acid (AZA) is a mobile priming signal. Here, we show that the lipid transfer protein (LTP)-like AZI1 and its closest paralog EARLI1 are necessary for SAR, ISR and the systemic movement and uptake of AZA in Arabidopsis. Imaging and fractionation studies indicate that AZI1 and EARLI1 localize to expected places for lipid exchange/movement to occur. These are the ER/plasmodesmata, chloroplast outer envelopes and membrane contact sites between them. Furthermore, these LTP-like proteins form complexes and act at the site of SAR establishment. The plastid targeting of AZI1 and AZI1 paralogs occurs through a mechanism that may enable/facilitate their roles in signal mobilization.


Subject(s)
Arabidopsis Proteins/metabolism , Arabidopsis/metabolism , Chloroplasts/metabolism , Amino Acid Sequence , Arabidopsis/immunology , Molecular Sequence Data , Proline-Rich Protein Domains
12.
J Genet Genomics ; 41(6): 327-38, 2014 Jun 20.
Article in English | MEDLINE | ID: mdl-24976122

ABSTRACT

Seed dormancy is an important agronomic trait in cereals. Using deep dormant (N22), medium dormant (ZH11), and non-dormant (G46B) rice cultivars, we correlated seed dormancy phenotypes with abscisic acid (ABA) and gibberellin (GA) metabolism gene expression profiles and phytohormone levels during seed development and imbibition. A time course analysis of ABA and GA content during seed development showed that N22 had a high ABA level at early and middle seed developmental stages, while at late developmental stage it declined to the level of ZH11; however, its ABA/GA ratio maintained at a high level throughout seed development. By contrast, G46B had the lowest ABA content during seed development though at early developmental stage its ABA level was close to that of ZH11, and its ABA/GA ratio peaked at late developmental stage that was at the same level of ZH11. Compared with N22 and G46B, ZH11 had an even and medium ABA level during seed development and its ABA/GA ratio peaked at the middle developmental stage. Moreover, the seed development time-point having high ABA/GA ratio also had relatively high transcript levels for key genes in ABA and GA metabolism pathways across three cultivars. These indicated that the embryo-imposed dormancy has been induced before the late developmental stage and is determined by ABA/GA ratio. A similar analysis during seed imbibition showed that ABA was synthesized in different degrees for the three cultivars. In addition, water uptake assay for intact mature seeds suggested that water could permeate through husk barrier into seed embryo for all three cultivars; however, all three cultivars showed distinct colors by vanillin-staining indicative of the existence of flavans in their husks, which are dormancy inhibition compounds responsible for the husk-imposed dormancy.


Subject(s)
Abscisic Acid/metabolism , Gibberellins/metabolism , Hormones/metabolism , Oryza/genetics , Plant Proteins/metabolism , Seeds/genetics , Oryza/growth & development , Plant Dormancy , Plant Proteins/genetics , Seeds/growth & development , Transcriptome
13.
Int J Mol Med ; 33(3): 736-42, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24366308

ABSTRACT

There are statistical data indicating that diabetes is a risk factor for Parkinson's disease (PD). Methylglyoxal (MG), a biologically reactive byproduct of glucose metabolism, the levels of which have been shown to be increase in diabetes, reacts with dopamine to form 1-acetyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (ADTIQ); this formation may provide further insight into the connection between PD and diabetes. In this study, we investigated the role of ADTIQ in these two diseases to determine in an aim to enhance our understanding of the link between PD and diabetes. To this end, a cell model of hyperglycemia and a rat model of diabetes were established. In the cell model of hyperglycemia, compared with the control group, the elevated glucose levels promoted free hydroxyl radical formation (p<0.01). An ADTIQ assay was successfully developed and ADTIQ levels were detected and quantified. The levels of its precursors, MG and dopamine (DA), were determined in both the cell model of hyperglycemia and the rat model of diabetes. The proteins related to glucose metabolism were also assayed. Compared with the control group, ADTIQ and MG levels were significantly elevated not only in the cell model of hyperglycemia, but also in the brains of rats with diabetes (p<0.01). Seven key enzymes from the glycolytic pathway were found to be significantly more abundant in the brains of rats with diabetes. Moreover, it was found that adenosine triphosphate (ATP) synthase and superoxide dismutase (SOD) expression levels were markedly decreased in the rats with diabetes compared with the control group. Therefore, ADTIQ expression levels were found to be elevated under hyperglycemic conditions. The results reported herein demonstrate that ADTIQ, which is derived from MG, the levels of which are increased in diabetes, may serve as a neurotoxin to dopaminergic neurons, eventually leading to PD.


Subject(s)
Diabetes Complications/genetics , Isoquinolines/metabolism , Neurotoxins/metabolism , Parkinson Disease/genetics , Tetrahydroisoquinolines/metabolism , Animals , Diabetes Complications/metabolism , Diabetes Complications/pathology , Diabetes Mellitus, Experimental/genetics , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Experimental/pathology , Disease Models, Animal , Dopaminergic Neurons/metabolism , Dopaminergic Neurons/pathology , Glucose/metabolism , Hydroxyl Radical/metabolism , Hyperglycemia/genetics , Hyperglycemia/pathology , Isoquinolines/chemistry , Neurotoxins/chemistry , Parkinson Disease/etiology , Parkinson Disease/metabolism , Rats
14.
Gene ; 506(1): 50-61, 2012 Sep 10.
Article in English | MEDLINE | ID: mdl-22759515

ABSTRACT

EARLI1 is an Arabidopsis gene with pleiotropic effects previously shown to have auxiliary functions in protecting plants against freezing-induced cellular damage and promoting germinability under low-temperature and salinity stresses. Here we determined whether recombinant EARLI1 protein has anti-fungal activity. Recombinant EARLI1 protein lacking its signal peptide was produced in Escherichia coli BL21(DE3) using isopropyl ß-d-1-thiogalactopyranoside (IPTG) induction and the prokaryotic expression vector pET28a. Expression of EARLI1 was analyzed by Western blotting and the protein was purified using affinity chromatography. Recombinant EARLI1 protein was applied to fungal cultures of Saccharomyces cerevisiae, Botrytis cinerea and Fusarium oxysporum, and membrane permeability was determined using SYTOX green. Full-length EARLI1 was expressed in S. cerevisiae from the GAL1 promoter using 2% galactose and yeast cell viability was compared to control cells. Our results indicated that application of recombinant EARLI1 protein to B. cinerea and F. oxysporum could inhibit the growth of the necrotrophic fungi. Besides, addition of the recombinant protein to liquid cultures of S. cerevisiae significantly suppressed yeast growth and cell viability by increasing membrane permeability, and in vivo expression of the secreted form of EARLI1 in S. cerevisiae also had a remarkable inhibition effect on the growth of yeast cells.


Subject(s)
Antifungal Agents/metabolism , Antifungal Agents/pharmacology , Arabidopsis Proteins/genetics , Arabidopsis Proteins/pharmacology , Amino Acid Sequence , Antifungal Agents/chemistry , Antigens, Plant/chemistry , Antigens, Plant/genetics , Antigens, Plant/pharmacology , Arabidopsis/genetics , Arabidopsis/physiology , Arabidopsis Proteins/chemistry , Base Sequence , Botrytis/drug effects , Botrytis/growth & development , Botrytis/pathogenicity , Carrier Proteins/chemistry , Carrier Proteins/genetics , Carrier Proteins/pharmacology , Cell Membrane Permeability/drug effects , DNA, Plant/genetics , Escherichia coli/genetics , Escherichia coli/metabolism , Fusarium/drug effects , Fusarium/growth & development , Fusarium/pathogenicity , Gene Expression , Genes, Plant , Genetic Vectors , Models, Molecular , Molecular Sequence Data , Plant Proteins/chemistry , Plant Proteins/genetics , Plant Proteins/pharmacology , Protein Conformation , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/pharmacology , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/growth & development , Sequence Homology, Amino Acid
15.
Radiat Res ; 178(1): 75-85, 2012 Jul.
Article in English | MEDLINE | ID: mdl-22686864

ABSTRACT

Dragon's blood is a bright red resin obtained from Dracaena cochinchinensis. It is a traditional medicinal that is used for wound healing and to stop bleeding. Its main biological activity appears to be from phenolic compounds found in Dragon's blood. In this study, the radioprotective effects of Dragon's blood were examined after whole brain irradiation of rats with either 100 MeV/u Carbon (12)C(6+) heavy ions or (60)Co γ-rays. The amounts of radiation-induced oxidative stress, inflammatory cytokines and apoptosis in irradiated rat brains were compared with and without Dragon's blood treatment. Compared to the "irradiation only" control group, the Dragon's blood treatment group significantly decreased malondialdehyde and hydrogen peroxide levels, and increased superoxide dismutase activity and glutathione levels induced by oxidative stress in radiation exposed rats (P < 0.05). Dragon's blood also significantly reduced radiation-induced inflammatory cytokines of tumor necrosis factor-α, interferon-γ and interleukin-6 levels (P < 0.05) and inhibited hippocampal neuronal apoptosis in (60)Co γ-ray irradiated rats. Furthermore, Dragon's blood significantly increased expression of brain-derived neurophic factor and inhibited the expression of pro-apoptotic caspase 3 (P < 0.05-0.01). Finally, Dragon's blood significantly inhibited expression of the AP-1 transcription factor family members c-fos and c-jun proteins (P < 0.05-0.01). The results obtained here suggest that Dragon's blood has radioprotective properties in rat brains after both heavy ions and (60)Co γ-ray exposure.


Subject(s)
Brain/radiation effects , Plant Extracts/pharmacology , Radiation Injuries, Experimental/prevention & control , Radiation-Protective Agents/pharmacology , Animals , Apoptosis/radiation effects , Brain/metabolism , Brain-Derived Neurotrophic Factor/analysis , Gamma Rays , Male , Oxidative Stress , Rats , Rats, Wistar
16.
PLoS Genet ; 7(7): e1002196, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21829379

ABSTRACT

Photosynthesis is the final determinator for crop yield. To gain insight into genes controlling photosynthetic capacity, we selected from our large T-DNA mutant population a rice stunted growth mutant with decreased carbon assimilate and yield production named photoassimilate defective1 (phd1). Molecular and biochemical analyses revealed that PHD1 encodes a novel chloroplast-localized UDP-glucose epimerase (UGE), which is conserved in the plant kingdom. The chloroplast localization of PHD1 was confirmed by immunoblots, immunocytochemistry, and UGE activity in isolated chloroplasts, which was approximately 50% lower in the phd1-1 mutant than in the wild type. In addition, the amounts of UDP-glucose and UDP-galactose substrates in chloroplasts were significantly higher and lower, respectively, indicating that PHD1 was responsible for a major part of UGE activity in plastids. The relative amount of monogalactosyldiacylglycerol (MGDG), a major chloroplast membrane galactolipid, was decreased in the mutant, while the digalactosyldiacylglycerol (DGDG) amount was not significantly altered, suggesting that PHD1 participates mainly in UDP-galactose supply for MGDG biosynthesis in chloroplasts. The phd1 mutant showed decreased chlorophyll content, photosynthetic activity, and altered chloroplast ultrastructure, suggesting that a correct amount of galactoglycerolipids and the ratio of glycolipids versus phospholipids are necessary for proper chloroplast function. Downregulated expression of starch biosynthesis genes and upregulated expression of sucrose cleavage genes might be a result of reduced photosynthetic activity and account for the decreased starch and sucrose levels seen in phd1 leaves. PHD1 overexpression increased photosynthetic efficiency, biomass, and grain production, suggesting that PHD1 plays an important role in supplying sufficient galactolipids to thylakoid membranes for proper chloroplast biogenesis and photosynthetic activity. These findings will be useful for improving crop yields and for bioenergy crop engineering.


Subject(s)
Galactolipids/biosynthesis , Oryza/enzymology , Photosynthesis/genetics , UDPglucose 4-Epimerase/genetics , UDPglucose 4-Epimerase/metabolism , Carbon/metabolism , Chloroplasts/genetics , Chloroplasts/metabolism , Gene Expression/genetics , Gene Expression Regulation, Plant , Homeostasis/genetics , Intracellular Space/metabolism , Mutation/genetics , Oryza/classification , Oryza/genetics , Phenotype , Phylogeny , Plant Leaves/genetics , Plant Leaves/metabolism , Plants, Genetically Modified , Protein Transport/genetics
17.
Planta ; 234(3): 565-77, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21556912

ABSTRACT

The effect of the hybrid proline-rich protein (HyPRP) gene EARLI1 on the rate of germination (germinability) of Arabidopsis seeds and seedling growth under low temperature and salt stress conditions was investigated. EARLI1 was induced during germination in embryonic tissues, and was strongly expressed in certain parts of young seedlings. Comparisons of control, overexpressing (OX), and knockout (KO) lines indicated that higher than wild type levels of EARLI1 improved germinability, root elongation, and reduction of sodium accumulation in leaves under salt stress, as well as germinability under low-temperature stress. Abscisic acid (ABA) contents were relatively low after prolonged salt stress, suggesting that EARLI1 has an ABA-independent effect on germinability under these conditions. Overexpression of EARLI1 during germination enhanced the sensitivity of seeds to exogenously applied ABA, suggesting that EARLI1 has an ABA-dependent negative effect on seed germinability under high ABA stress conditions. Well-known stress response marker genes such as COR15a, KIN1, P5SC1, and RD29 were unaffected whereas P5SC2, RD22, or RAB18 were only slightly affected in OX and KO plants. The pleiotropic effects of EARLI1 during stress and an absence of strong regulatory effects on stress marker genes suggest that this HyPRP gene has an auxiliary role for various stress protection responses in Arabidopsis.


Subject(s)
Arabidopsis/growth & development , Arabidopsis/genetics , Germination/genetics , Abscisic Acid/metabolism , Arabidopsis/metabolism , Cold Temperature , Cotyledon/genetics , Cotyledon/growth & development , Gene Expression Regulation, Plant , Gene Knockdown Techniques , Genes, Plant , Germination/drug effects , Plant Growth Regulators , Plant Leaves/chemistry , Plant Proteins/metabolism , Plant Roots/growth & development , Plants, Genetically Modified/metabolism , Salt Tolerance/physiology , Seedlings/genetics , Seedlings/growth & development , Seeds/genetics , Seeds/growth & development , Seeds/metabolism , Sodium Chloride/pharmacology
18.
J Plant Physiol ; 168(13): 1576-87, 2011 Sep 01.
Article in English | MEDLINE | ID: mdl-21492954

ABSTRACT

AZI1 (AZELAIC ACID INDUCED 1) of Arabidopsis thaliana could be induced by azelaic acid and was involved in priming of systemic plant immunity. In the present work, expression of AZI1 in response to low temperature was investigated via RNA gel blot analysis. AZI1 could be induced slowly by cold stress and more than 6h treatment at 4°C was required to detect an increase in mRNA abundance. However, the high expression state could not be maintained stably and would decline to basal level when the plants were transferred to room temperature. In order to clarify the function of AZI1 in resistance to abiotic stresses, overexpressing, RNA interference and T-DNA knockout lines of this gene were used in electrolyte leakage assays. Overexpression of AZI1 resulted in reduced electrolyte leakage during freezing damage. In contrast, AZI1 knockdown and knockout lines showed increased tendencies in cellular damage after freezing treatment. To further validate the potential resistance of AZI1 to low-temperature stress, Saccharomyces cerevisiae cells were transformed with pESC-AZI1 in which AZI1 was under the control of GAL1 promoter. Compared to yeast cells containing empty pESC-URA, the survival rate of yeast cells harboring AZI1 increased obviously after freezing treatment. All these results suggested that AZI1 might be multifunctional and associated with cold tolerance of Arabidopsis.


Subject(s)
Acclimatization/physiology , Arabidopsis Proteins/metabolism , Arabidopsis/physiology , Gene Expression Regulation, Plant/physiology , Saccharomyces cerevisiae/physiology , Amino Acid Sequence , Arabidopsis/genetics , Arabidopsis/metabolism , Arabidopsis Proteins/genetics , Base Sequence , Electrolytes , Freezing/adverse effects , Molecular Sequence Data , Mutation , Plant Immunity , Plant Leaves/genetics , Plant Leaves/metabolism , Plants, Genetically Modified/genetics , Plants, Genetically Modified/metabolism , Plants, Genetically Modified/physiology , RNA, Messenger/genetics , RNA, Plant/genetics , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Sequence Alignment , Sequence Analysis, DNA , Stress, Physiological
19.
J Ethnopharmacol ; 135(2): 510-4, 2011 May 17.
Article in English | MEDLINE | ID: mdl-21463670

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Dragon's Blood from Dracaena cochinchinensis (Lour.) S.C. Chen (Yunnan, China), as a traditional Chinese medicinal herb, was shown to have certain antithrombotic effects. A new preparation process was used to extract effective components from Dragon's Blood. A 95% ethanol extract A (EA) and a precipitate B (PB) fraction were obtained and compared. Reliability of the preparation process was validated by pharmacodynamic experiments. MATERIALS AND METHODS: A rat/mouse thrombosis and blood stasis model was developed for this study, and EA and PB effects on thrombosis, platelet functions and blood coagulation activities were analyzed. RESULTS: It was observed that the EA fraction had significantly better inhibitory effects than the PB fraction on thrombosis (p<0.05), platelet aggregation function (p<0.01) and anticoagulation activity (p<0.05-0.01). CONCLUSIONS: The results obtained here showed that EA fraction from Dragon's Blood contained pharmacologically effective compounds with antithrombotic effects, partially improving platelet function and anticoagulation activity.


Subject(s)
Anticoagulants/pharmacology , Antithrombins/pharmacology , Plant Extracts/pharmacology , Platelet Aggregation Inhibitors/pharmacology , Animals , Mice , Plant Extracts/chemistry , Rats , Rats, Wistar
20.
Planta Med ; 75(15): 1618-24, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19548190

ABSTRACT

IN VITRO plant regeneration of Gentiana macrophylla Pall. and determination of gentiopicroside content during somatic embryogenesis are described in the present work. The highest percentage of embryogenic callus formation was observed in Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.0 mg/L 6-benzylaminopurine (BA). Calli were subcultured on MS medium containing 1.0 mg/L 2,4-D, 1.0 mg/L BA and 500 mg/L lactalbumin hydrolysate (LH) at intervals of 25 days. A higher frequency of somatic embryo maturation was achieved on MS medium containing B5 vitamins (MB) supplemented with different concentrations of 1-naphthaleneacetic acid (NAA) and BA than with a combination of NAA and kinetin (KT). Addition of AgNO(3) improved maturation of somatic embryos while thidiazuron (TDZ) promoted vitrification. The gentiopicroside contents of embryogenic calli and globular-, heart-, torpedo-, and cotyledon-shaped embryoids were determined by high-performance liquid chromatography (HPLC). Gentiopicroside was not detectable in embryogenic calli, but in all types of somatic embryos. The highest gentiopicroside content was observed in cotyledon-shaped embryoids, reaching more than 12 mg/g dry weight.


Subject(s)
Gentiana/metabolism , Glucosides/biosynthesis , Seeds/metabolism , Chromatography, High Pressure Liquid , Culture Media , Gentiana/embryology , Gentiana/growth & development , Iridoid Glucosides , Iridoids , Phenylurea Compounds , Silver Nitrate , Thiadiazoles , Tissue Culture Techniques
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