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Background
Mycobacterium smegmatis, a rapidly growing non-tuberculosis mycobacterium, is a good model for studying the pathogenesis of tuberculosis because of its genetic similarity to Mycobacterium tuberculosis (Mtb). Macrophages remove mycobacteria during an infection. Macrophage apoptosis is a host defense mechanism against intracellular bacteria. We have reported that endoplasmic reticulum (ER) stress is an important host defense mechanism against Mtb infection.Results
In this study, we found that M. smegmatis induced strong ER stress. M. smegmatis-induced reactive oxygen species (ROS) play a critical role in the induction of ER stress-mediated apoptosis. Pretreatment with an ROS scavenger suppressed M. smegmatis-induced ER stress. Elimination of ROS decreased the ER stress response and significantly increased the intracellular survival of M. smegmatis. Interestingly, inhibition of phagocytosis significantly decreased ROS synthesis, ER stress response induction, and cytokine production.Conclusions
Phagocytosis of M. smegmatis induces ROS production, leading to production of proinflammatory cytokines. Phagocytosis-induced ROS is associated with the M. smegmatis-mediated ER stress response in macrophages. Therefore, phagocytosis plays a critical role in the induction of ER stress-mediated apoptosis during mycobacterial infection.2.
This study examined the effects of 5-aminolevulinic acid (ALA) application on photosynthesis, activity and gene expression of key antioxidant enzymes, and on proline accumulation in tomato (Lycopersicon esculentum Mill. ‘Hezuo 903’) seedlings under NaCl stress. NaCl stress significantly decreased the net photosynthetic rates and inhibited the activity of photosystem II, whereas exogenous ALA application significantly restored the net photosynthetic rates, quantum yield of electron transport, and energy conversion efficiency of photosystem II of tomato under NaCl stress. Production of superoxide, hydrogen peroxide, and malondialdehyde strongly increased in response to NaCl stress, and these increases were significantly counteracted by ALA. ALA increased the activity of reactive oxygen species (ROS) scavenging antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, and upregulated the expression of SOD, APX, and POD, genes that encode these enzymes in NaCl-treated plants. ALA simultaneously increased proline accumulation in tomato seedlings under NaCl stress by regulating the expression of genes that encode ALA biosynthetic enzymes and that control proline biosynthesis and metabolism, for example, expression of GluRS and GluTR was downregulated, accompanied by a significant increase in the expression of P5CS and decline in the expression of ProDH. ALA provided protection against NaCl stress by increasing photosynthetic capacity, regulating antioxidant enzyme gene expression and proline accumulation, and decreasing ROS accumulation and lipid peroxidation in tomato. 相似文献
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S. Cao X.-H. Du L.-H. Li Y.-D. Liu L. Zhang X. Pan Y. Li H. Li H. Lu 《Russian Journal of Plant Physiology》2017,64(2):224-234
Reactive oxygen species (ROS) play key roles in plants and are regulated by several ROS-scavenging enzymes. Ascorbate peroxidase (APX), which catalyzes the reduction of hydrogen peroxide to water, a vital part of ROS formation, plays a significant role in higher plants. In this study, a cytosolic APX gene from Populus tomentosa, named PcAPX, was identified and characterized. Recombinant PcAPX had a calculated mass of 33.24 kD and showed high activity towards ascorbic acid (ASA) and hydrogen peroxide (H2O2). Real-time PCR analysis showed that APX mRNA expression levels were higher in leaves than roots or stems of P. tomentosa. Compared with wild-type, transgenic tobacco plants overexpressing PcAPX showed no significant difference in morphology under normal conditions. However, the transgenic plants were more resistant to drought, salt and oxidative stress conditions, as shown by decreased levels of malondialdehyde and increased levels of chlorophyll. Moreover, decreased H2O2 levels, increased ASA consumption, an increase in the NADP to NADPH ratio, and higher APX activity in the transgenic plants suggested an increased ability to eliminate ROS. These data suggest that PcAPX overexpression in transgenic tobacco plants can enhance tolerance to drought, salt and oxidative stress. Therefore, APX has a crucial role in abiotic stress tolerance in plants. 相似文献
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Anushka Moothoo-Padayachie Boby Varghese N. W. Pammenter Patrick Govender Sershen 《Acta Physiologiae Plantarum》2018,40(1):14
This study compared the responses of Avicennia marina and Trichilia dregeana seeds, both of which are recalcitrant, to partial dehydration and storage. Seeds of A. marina exhibited a faster rate of water and viability loss (± 50% viability loss in 4 days) during partial dehydration, compared with T. dregeana (± 50% viability loss in 14 days). In A. marina embryonic axes, reactive oxygen species (ROS) production peaked on 4 days of dehydration and was accompanied by an increase in the GSH:GSSG ratio; it appears that the glutathione system alone could not overcome dehydration-induced oxidative stress in this species. In A. marina, ROS and axis water content levels increased during hydrated storage and were accompanied by a decline in the GSH:GSSG ratio and rapid viability loss. In T. dregeana embryonic axes, ROS production (particularly hydrogen peroxide) initially increased and thereafter decreased during both partial dehydration and hydrated storage. Unlike in A. marina embryonic axes, this reduced ROS production was accompanied by a decline in the GSH:GSSG ratio. While T. dregeana seeds may have incurred some oxidative stress during storage, a delay in and/or suppression of the ROS-based trigger for germination may account for their significantly longer storage longevity compared with A. marina. Mechanisms of desiccation-induced seed viability loss may differ across recalcitrant-seeded species based on the rate and extent to which they lose water during partial drying and storage. While recalcitrant seed desiccation sensitivity and, by implication, storage longevity are modulated by redox metabolism, the specific ROS and antioxidants that contribute to this control may differ across species. 相似文献
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Hongmei Lin Jianyu He Weiwei Lin Yingzhe Li Changxun Fang Wenxiong Lin 《Plant Growth Regulation》2018,86(2):149-157
Silicon (Si) is known for its role in regulating the response of plants to imposed abiotic stresses. Since the stresses generally hinder production of a crop, such as rice, the exploration of the biochemistry and plant physiology relating to the function is of interest. Indeed, recently, there were reports on the function of Lsi1 in regulating the tolerance of rice to cadmium (Cd) stress. This study compared the kinetics of the Cd uptakes in Lemont wild type rice and its transgenic lines exposed to Cd with or without exogenous Si supply. At the same time, changes on the endogenous phytohormones and growth of the rice seedlings were monitored. Genetically, Lsi1 overexpression was found to downregulate Km and Vmax of Cd uptake kinetics in the plants under Cd stress, especially in the presence of Si. On the other hand, Lsi1 RNAi upregulated Km and Vmax regardless whether Si was present or not. It implied that Lsi1 could be capable of regulating Si as well as Cd transports. Under Cd stress, addition of Si reduced the Cd uptake of the rice lines in the order of Lsi1-overexpression line?>?Lemont?>?Lsi1-RNAi line. In addition, it also affected the chlorophyll biosynthesis and dry mass accumulation of the rice plants under Cd stress. Analyses on phytohormones including IAA, GA3, JA, SA and ABA, as well as physiological functions, of the seedlings further verified the active involvement of Lsi1 in the complex defense system of the plants against Cd stress. 相似文献
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Gene expression and activity of antioxidant enzymes in rice plants,cv. BRS AG,under saline stress 总被引:1,自引:0,他引:1
Tatiana Rossatto Marcelo Nogueira do Amaral Letícia Carvalho Benitez Isabel Lopes Vighi Eugenia Jacira Bolacel Braga Ariano Martins de Magalhães Júnior Mara Andrade Colares Maia Luciano da Silva Pinto 《Physiology and Molecular Biology of Plants》2017,23(4):865-875
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Satish K. Verma Kathryn Kingsley Marshall Bergen Camille English Matthew Elmore Ravindra N. Kharwar James F. White 《Plant and Soil》2018,422(1-2):223-238
Background and Aims
Leersia oryzoides, a wild relative of rice (Oryza sativa), may carry potential seed-borne bacterial endophytes which could be used to enhance growth of rice. We hypothesized that seed-associated bacteria from L. oryzoides would be compatible with rice and promote seedling growth, development, and survival.Methods
We isolated bacteria from seed of L. oryzoides and checked compatibility with rice as well as Bermuda grass seeds for seedling growth promotion. Internal colonisation of bacteria into root cells was observed by ROS staining and microscopic observation. Growth promoting bacteria were evaluated for IAA production, phosphate solubilization and antifungal activities.Results
Overall, ten bacteria were found to be growth promoting in rice seedlings with effects including restoration of root gravitropic response, increased root and shoot growth, and stimulation of root hair formation. All bacteria were identified by 16S rDNA sequencing. Six bacteria were found to become intracellular in root parenchyma and root hairs in rice and in Bermuda grass seedlings. Six bacteria were able to produce IAA in LB broth with highest (47.06 ± 1.99 μg ml?1) by LTE3 (Pantoea hericii). Nine isolates solubilized phosphate and inhibited at least one soil borne fungal pathogen.Conclusions
Seed bacteria of L. oryzoides are compatible with rice. Many of these bacteria become intracellular, induce root gravitropic response, increase root and shoot growth, and stimulate root hair formation in both rice and Bermuda grass seedlings. Presence of bacteria protects seedlings from soil pathogens during seedling establishment. This research suggests that bioprospecting microbes on near relatives of rice and other crop plants may be a viable strategy to obtain microbes to improve cultivation of crops.10.
Yanxiao Tan Xiaoyu Wei Ping Wang Xun Sun Mingjun Li Fengwang Ma 《Plant Molecular Biology Reporter》2016,34(1):62-75
Cystatins, or phytocystatins (PhyCys), comprise a family of plant-specific inhibitors of cysteine proteinases. They are thought to help regulate endogenous processes and protect plants against biotic or abiotic stresses, such as heat, salinity, cold, water deficit, chilling, and abscisic acid (ABA) treatment. We isolated and identified a novel cystatin gene from Malus prunifolia, MpCYS5. Its expression was typically induced by salt stress treatment; ectopic expression in Arabidopsis enhanced salt tolerance. Physiological parameters confirmed this phenotype, with the transgenics having remarkably lower electrolyte leakage (EL) values, higher chlorophyll concentrations, and lower levels of malondialdehyde (MDA) upon salt treatment. In addition, the accumulation of reactive oxygen species was markedly regulated by MpCYS5 under stress conditions, as shown by fluctuations in the concentrations of hydrogen peroxide and superoxide radicals and the activities of antioxidant enzymes. We also noted that this gene modulated tunicamycin (TM)-induced endoplasmic reticulum (ER) stress tolerance and functioned in the unfolded protein response (UPR)-signaling pathway in Arabidopsis. This was confirmed by the expression of eight ER stress-responsive genes. All marker genes examined were strongly induced in the wild type, while most of them maintained relatively stable over time in the transgenics. These results demonstrated that ectopic expression of a cystatin gene is associated with salt-tolerant and TM-tolerant phenotypes. Therefore, the discovery of MpCYS5 from M. prunifolia might establish a molecular link between the ER stress response and salt tolerance in plants. 相似文献
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Asiye Sezgin Cansu Altuntaş Aykut Sağlam Rabiye Terzi Mehmet Demiralay Asim Kadıoğlu 《Acta Physiologiae Plantarum》2018,40(8):141
Leaf rolling observed in some crops such as maize, rice, wheat and sorghum is an indicator of decreased water status. Moderate leaf rolling not tightly or early increases the photosynthesis and grain yield of crop cultivars under environmental stresses. Moreover, the effects of exogenous abscisic acid (ABA) on stomatal conductance, water status and synthesis of osmotic compounds are a well-known issue in plants subjected to water deficit. However, it is not clear how the cross-talk of ABA with H2O2 and osmolyte compounds affects the leaf rolling mechanism. Regulation mechanism of leaf rolling by ABA has been first studied in maize seedlings under drought stress induced by polyethylene glycol 6000 (PEG 6000) in this study. ABA treatment under drought stress reduced hydrogen peroxide (H2O2) content and the degree of leaf rolling (%) while the treatment-induced ABA synthesis, osmolyte levels (proline, polyamine and total soluble sugars) and some antioxidant enzyme activities in comparison to the plants that were not treated with ABA. Furthermore, exogenous ABA up-regulated the expression levels of arginine decarboxylase (ADC) and pyrroline-5-carboxylate synthase (P5CS) genes and down-regulated polyamine oxidase (PAO), diamine oxidase (DAO) and proline dehydrogenase (ProDH) gene expressions. When endogenous ABA content was decreased by the treatment of fluoridone (FLU) that is an ABA inhibitor, leaf rolling degree (%), H2O2 content and antioxidant enzyme activities increased, but osmolyte levels, ADC and P5CS gene expressions decreased. Finally, the treatment of ABA to maize seedlings exposed to drought stress resulted in the stimulation of the antioxidant system, osmotic adjustment and reduction of leaf rolling. We concluded that ABA can be a signal compound cross-talking H2O2, proline and polyamines and thus involved in the leaf rolling mechanism by providing osmotic adjustment. The results of this study can be used to provide data for the molecular breeding of maize hybrids with high grain yield by means of moderately rolled leaves. 相似文献
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Jiahui Wang Yunxia Fang Bin Tian Xiaoqin Zhang Dali Zeng Longbiao Guo Jiang Hu Dawei Xue 《Plant Growth Regulation》2018,85(2):329-335
Cadmium (Cd) is a non-essential toxic metal that is primarily released into the environment from artificial sources in recent decades. To investigate the genetics of Cd toxicity tolerance at the seedling stage in rice, a QTL analysis was carried out under cadmium stress conditions with two toxicity-linked traits—leaf rolling (LR) and the green leaf ratio (GLR). Using 127 rice lines of doubled haploid (DH) population derived from a cross between a japonica JX17 and indica ZYQ8, two QTLs for LR (qLR-1 and qLR-9) and one QTL for GLR (qGLR-3) were detected. Among them, the phenotypic variation of qLR-1 and qGLR-3 were 19.27 and 16.09, values which are useful for marker-assistant selection in breeding elite rice cultivars that have the capacity to tolerate Cd. The results further demonstrate that visual measurements of both LR and GLR in seedlings are effective methods for screening tolerant rice germplasm in cadmium stress scenarios. 相似文献
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Background and aims
Nitrogen (N) deficiency and drought are two key limiting factors for rice production worldwide, but the relationship of drought stress with N homeostasis in rice is rarely advanced. The aim of this study was to dissect the physiological effects of drought stress on rice growth that coupled unbalanced N metabolism.Results
Water-deficient stress (WD) limited stomatal aperture function and activity of Rubisco carboxylase to photosynthesis. The rate of total electron transport (Jt) and the electron to carboxylation (Jc) were considerably decreased, whereas the proportion of e? flow to photorespiration was stimulated by WD, especially at 1600 μmol m?2 s?1 PPFD. Concurrently, the expressions of glycolate oxidase genes (GOX1, GOX5) and glycine decarboxylase complex (GDCH, GDCP and GDCT) were significantly induced in leaves of WD treatment, which led to the accumulation of reactive oxygen species in leaves. With the photosynthetic change, nitrate uptake and reduction were suppressed. Moreover, the enhanced photorespiration generated excess NH3 accumulation in leaves and stimulated the expressions of GS1;1, GS1;2 and GS2, which were tightly coupled with the expressions of PEPC1 and PEPC2 under WD stress.Conclusions
Our results suggest that the inhibited nitrate reduction associated with diminished electron transport rate, and the photorespiration-associated accumulation of hydrogen peroxide and NH3 were critical in the drought-induced rice growth inhibition.15.
Yuxia Zhang Xiaoling Guo Yuchao Cui Chiming Guo Liang Chen 《Journal of Plant Biology》2017,60(5):523-532
In this paper, we characterized a differentially expressed receptor-like cytoplasmic kinase XCRK, which confers resistance to bacterial leaf streak (BLS). We analyzed the tissue expression of XCRK and showed that XCRK was widely expressed in multiple rice (Oryza sativa) organs, including internodes, roots, leaves and flowers. In addition, the expression of XCRK was significantly induced by ABA, salt and H2O2 treatments, suggesting its function in these pathways. The XCRK-overexpressing transgenic seedlings exhibited higher tolerance to Xanthomonas oryzae pv.oryzicola (Xoc) compared with the wild-type seedlings. Furthermore, XCRK-overexpressing seedlings showed stronger antioxidant capacity with reduced MDA and H2O2 content and higher antioxidant enzyme activities. It has been hypothesized that the enhanced Xoc tolerance was attributed to the improved expression of resistance-responsive factors positively regulated by XCRK. In accordance with this, the expression of resistance and oxidation-related genes Wrky77, Wrky13, PAL1, PR5, Fe-SOD and SodCc2 were up-regulated by the overexpression of XCRK, which might contribute collectively to the increased Xoc tolerance. Overall, overexpression of XCRK could enhance the antioxidant capacity and Xoc tolerance in rice. 相似文献
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Molecular characterization and subcellular localization of salt-inducible lipid transfer proteins in rice 总被引:1,自引:0,他引:1
Rice (Oryza sativa L.) is a salt-sensitive species. Salt stress can cause injury to the plant cellular membrane. Plant lipid transfer proteins (LTPs) are abundant lipid binding proteins that are important in membrane vesicle biogenesis and trafficking, however, the biological importance of LTPs on salt-stress response in rice remains unclear. Therefore, salt-responsive rice LTPs were identified and characterized in this study. Microarray analysis showed seven genes positively regulated by salinity, including five Ltp genes (LtpII.3, LtpII.5, LtpII.6, LtpV.1, and LtpV.2) and two Ltp-like (LtpL; LtpL1, and LtpL2) genes. Amino acid alignment revealed that all these Ltp and LtpL genes contained the N-terminal signal peptide. Apart from LtpL1, all salt-inducible Ltp genes had the conserved eight cysteine residue motifs backbone. Verification of gene expression to different stimuli in rice seedlings revealed that salt-regulated Ltp genes differentially responded to drought, cold, H2O2, abscisic acid (ABA) and CaCl2. Furthermore, the expression of Ltp and LtpL genes was tissue-specifically regulated by ABA-dependent and independent pathway. In silico analysis of a 1.5-kb 5’-upstream region of these genes showed regulatory cis-elements associated with ABA, calcium, and cold/drought responses. Three LtpII subfamily genes, including LtpII.3, LtpII.5, and LtpII.6, were strictly expressed in flowers and seeds, and LtpIII.1 mRNA strongly accumulated in stem tissue. Subcellular localization analysis of LTP-DsRed fusion proteins revealed that the five LTPs and two LTPLs localized at the endoplasmic reticulum. The results provide new clues to further understanding the biological functions of Ltp genes. 相似文献
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Ranjeet Kaur Anirban Chakraborty Rupam Kumar Bhunia Jagannath Bhattacharyya Asitava Basu Soumitra Kumar Sen Ananta Kumar Ghosh 《Journal of plant biochemistry and biotechnology.》2017,26(1):14-26
Identification and characterization of plant promoters from wild rice genotypes showing inducible expression under soil water stress (SWS) is desirable for transgene expression to generate stress tolerant rice cultivars. A comparative expression profiling of Wsi18, a group 3 LEA gene, revealed differential response under SWS conditions between modern cultivated rice (IR20) and its wild progenitor (Oryza nivara). Wsi18 promoter from O. nivara showed enhanced inducible expression of the reporter gusA gene, encoding β-glucuronidase, in transgenic rice plants in comparison to similar promoter from IR20. Deletion analysis unravelled the cis-acting regulatory elements minimally required for optimal expression of Wsi18 promoter from O. nivara under SWS condition. This is the first report of characterization of an inducible promoter from a wild rice genotype to drive the gene expression under water stress conditions. The Wsi18 promoter element from the wild rice genotype can be used in future genetic manipulation strategies for the generation of SWS tolerant rice cultivars with improved yield characteristics. 相似文献
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Late embryogenesis abundant (LEA) proteins are closely related to abiotic stress tolerance of plants. In the present study, we identified a novel Em-like gene from lettuce, termed LsEm1, which could be classified into group 1 LEA proteins, and shared high homology with Cynara cardunculus Em protein. The LsEm1 protein contained three different 20-mer conserved elements (C-element, N-element, and M-element) in the C-termini, N-termini, and middle-region, respectively. The LsEm1 mRNAs were accumulated in all examined tissues during the flowering and mature stages, with a little accumulation in the roots and leaves during the seedling stage. Furthermore, the LsEm1 gene was also expressed in response to salt, dehydration, abscisic acid (ABA), and cold stresses in young seedlings. The LsEm1 protein could effectively reduce damage to the lactate dehydrogenase (LDH) and protect LDH activity under desiccation and salt treatments. The Escherichia coli cells overexpressing the LsEm1 gene showed a growth advantage over the control under drought and salt stresses. Moreover, LsEm1-overexpressing rice seeds were relatively sensitive to exogenously applied ABA, suggesting that the LsEm1 gene might depend on an ABA signaling pathway in response to environmental stresses. The transgenic rice plants overexpressing the LsEm1 gene showed higher tolerance to drought and salt stresses than did wild-type (WT) plants on the basis of the germination performances, higher survival rates, higher chlorophyll content, more accumulation of soluble sugar, lower relative electrolyte leakage, and higher superoxide dismutase activity under stress conditions. The LsEm1-overexpressing rice lines also showed less yield loss compared with WT rice under stress conditions. Furthermore, the LsEm1 gene had a positive effect on the expression of the OsCDPK9, OsCDPK13, OsCDPK15, OsCDPK25, and rab21 (rab16a) genes in transgenic rice under drought and salt stress conditions, implying that overexpression of these genes may be involved in the enhanced drought and salt tolerance of transgenic rice. Thus, this work paves the way for improvement in tolerance of crops by genetic engineering breeding. 相似文献
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