作者机构：
[Gao, Xiang; An, Jing] Shaanxi Univ Sci & Technol, Sch Food & Biol Engn, Xian 710021, Peoples R China.;[Xu, Haiyan; Zhu, Zhaoxia; Gao, Xiang; Liu, Litao] Cent China Normal Univ, Sch Life Sci, Wuhan 430079, Peoples R China.;[Ji, Boyang] Chalmers Univ Technol, Dept Biol & Biol Engn, S-41296 Gothenburg, Sweden.;[Ye, Shuifeng] Shanghai Agrobiol Gene Ctr, Shanghai 201106, Peoples R China.;[Ye, Shuifeng] Shangrao Normal Univ, Coll Life Sci, Shangrao 334001, Peoples R China.
通讯机构：
[Gao, Xiang; Ye, Shuifeng] S;[Gao, Xiang; Ji, Boyang] C;Shaanxi Univ Sci & Technol, Sch Food & Biol Engn, Xian 710021, Peoples R China.;Cent China Normal Univ, Sch Life Sci, Wuhan 430079, Peoples R China.;Chalmers Univ Technol, Dept Biol & Biol Engn, S-41296 Gothenburg, Sweden.
摘要：
<jats:title>Summary</jats:title><jats:p>Environmental stressors, especially low temperature, are very common on the earth's dryland systems. Terrestrial cyanobacteria have evolved with cold adaptability in addition to extreme dryness and high irradiation resistance. The dryland soil surface‐dwelling species, <jats:italic>Nostoc flagelliforme</jats:italic>, serves as a potential model organism to gain insights into cyanobacterial cold adaptation. In this study, we performed transcriptomic analysis of <jats:italic>N</jats:italic>. <jats:italic>flagelliforme</jats:italic> samples in response to low temperature. The results revealed that the biological processes, such as terpenoid biosynthetic process, oxidoreductase activity, carbohydrate metabolism, biosynthesis of secondary metabolites, lipid and nitrogen metabolism, were significantly and dynamically changed during the cold stress. It was noteworthy that the transcription of the denitrification pathway for ammonia accumulation was enhanced, implying an importance for nitrogen utilization in stress resistance. In addition, characterization of a cold‐responsive hypothetical gene <jats:italic>csrnf1</jats:italic> found that it could greatly improve the cold‐resistant performance of cells when it was heterologously expressed in transgenic <jats:italic>Nostoc</jats:italic> sp. PCC 7120. It was also found that <jats:italic>csrnf1</jats:italic> transgenic strain exhibited resistance to nitrogen‐deficient environmental stress. Considering that dryland cyanobacteria have to cope with low temperature on infertile soils, this study would enrich our understanding on the importance of multifunction of the genes for environmental cold adaptation in drylands.</jats:p>
摘要：
Soil surface-dwelling cyanobacteria constitute an important part of the dryland ecosystem. The exopolysaccharide (EPS) matrix they establish plays multiple roles in helping cells cope with harsh environments and also improves soil physicochemical properties. Anthropogenic atmospheric nitrogen or sulfur depositions have arisen as an important environmental change in drylands. The acid moisture derived from the depositions will be absorbed by cyanobacterial EPS matrix and thus may pose a threat to cells. In this communication, we evaluated this potential impact in a dryland cyanobacterium, Nostoc flagelliforme, which is a representative polysaccharide-rich species and shows remarkable resistance to desiccation stress. A strong and resilient pH buffering property was found for the EPS matrix, mainly of the polysaccharide's role, and this could protect the cells from acid damage of pH 4-6, a general acidity range of rainwater in the world. Unlike in acid aquatic environments, terrestrial xeric environments ensure N. flagelliforme unlikely to undertake lasting severe acidification. Thus, protection of the EPS matrix for dryland cyanobacteria would be conducive to sustain their growth and ecological roles in face of atmospheric acid pollution.
关键词：
antioxidant;carotenoid;catalase;chlorophyll;chlorophyll a;peroxidase;pigment;protein;proteome;superoxide dismutase;bacterial protein;proteome;antioxidant activity;Article;carbohydrate metabolism;gene expression;hydration;light harvesting system;liquid chromatography-mass spectrometry;nonhuman;Nostoc;Nostoc flagelliforme;photosynthesis;priority journal;proteomics;rehydration;reverse transcription polymerase chain reaction;signal transduction;upregulation;water absorption;biosynthesis;gene expression profiling;gene expression regulation;metabolism;Nostoc;photosystem I;photosystem II;phycobilisome;Bacterial Proteins;Gene Expression Profiling;Gene Expression Regulation, Bacterial;Nostoc;Photosystem I Protein Complex;Photosystem II Protein Complex;Phycobilisomes;Proteome;Proteomics
摘要：
To adapt to xeric environments, microorganisms have evolved with the capability of the superior desiccation tolerance and rapid resuscitation after rehydration. Nostoc flagelliforme, a representative terrestrial cyanobacterium that is distributed in west and west-northern parts of China, serves as an ideal model for gaining insight in the physiological recovery mechanism. In this study, LC-MS/MS combined with isobaric chemical labeling technique (iTRAQ) was used to quantify dynamic changes of proteins in N. flagelliforme during the rehydration processes. Approximately 113 proteins were identified to be differentially expressed, with function mainly related to photosynthesis, defense response, biosynthesis, antioxidant system, and energy and carbohydrate metabolism. Among them, protective proteins including high light inducible proteins and antioxidants showed a down regulation trend during the rehydration process, while proteins involved in photosynthesis, biosynthesis and signaling pathways and regulation of gene expression tend to be up-regulated. These results might shed light on molecular mechanism for the N.flagelliforme response to hydration. SIGNIFICANCE: In this work, iTRAQ-based proteome expression profiling provides a holistic proteomic insight for N. flagelliforme in response to rehydration processes. Proteins involved in defense system could help to limit the damage to a repairable level and maintain cellular physiological integrity in the dried state. In addition, results in this work suggest that changes in expression of light-harvesting complexes phycobilisome is closely related to the switch of photosynthesis apparatus, while only a few proteins in PSI and PSII present significant expression change, which may indicate the integrity of PSI and PSII photosynthetic system.
摘要：
Environmental abiotic stresses are limiting factors for less tolerant organisms, including soil plants. Abiotic stress tolerance-associated genes from prokaryotic organisms are supposed to have a bright prospect for transgenic application. The drought-adapted cyanobacterium Nostoc flagelliforme is arising as a valuable prokaryotic biotic resource for gene excavation. In this study, we evaluated the salt-tolerant function and application potential of a candidate gene drnf1 from N. flagelliforme, which contains a P-loop NTPase (nucleoside-triphosphatase) domain, through heterologous expression in two model organisms Synechocystis sp. PCC 6803 and Arabidopsis thaliana. It was found that DRNF1 could confer significant salt tolerance in both transgenic organisms. In salt-stressed transgenic Synechocystis, DRNF1 could enhance the respiration rate; slow-down the accumulation of exopolysaccharides; up-regulate the expression of salt tolerance-related genes at a higher level, such as those related to glucosylglycerol synthesis, Na+/H+ antiport, and sugar metabolism; and maintain a better K+/Na+ homeostasis, as compared to the wild-type strain. These results imply that DRNF1 could facilitate salt tolerance by affecting the respiration metabolism and indirectly regulating the expression of important salt-tolerant genes. Arabidopsis was employed to evaluate the salt tolerance-conferring potential of DRNF1 in plants. The results show that it could enhance the seed germination and shoot growth of transgenic plants under saline conditions. In general, a novel prokaryotic salt-tolerant gene from N. flagelliforme was identified and characterized in this study, enriching the candidate gene pool for genetic engineering in plants.
摘要：
The terrestrial cyanobacterium Nostoc flagelliforme, which contributes to carbon and nitrogen supplies in arid and semi-arid regions, adopts a filamentous colony form. Owing to its herbal and dietary values, this species has been overexploited. Largely due to the lack of understanding on its morphogenesis, artificial cultivation has not been achieved. Additionally, it may serve as a useful model for recognizing the morphological adaptation of colonial cyanobacteria in terrestrial niches. However, it shows very slow growth in native habitats and is easily disintegrated under laboratory conditions. Thus, a novel experimental system is necessary to explore its morphogenetic mechanism. Liquid-cultured N. flagelliforme has been well developed for exopolysaccharide (EPS) production, in which microscopic colonies (micro-colonies) are generally formed. In this study, we sought to gain some insight into the morphogenesis of N. flagelliforme by examining the effects of two external factors, the EPS and environmental stress-related growth rate, on the morphological shaping of micro-colonies. Our findings indicate that the EPS matrix could act as a basal barrier, leading to the bending of trichomes during their elongation, while very slow growth is conducive to their straight elongation. These findings will guide future cultivation and application of this cyanobacterium for ecological improvement.
作者机构：
[Haiyan Xu] School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China;Authors to whom correspondence should be addressed.;School of Life Sciences, Ningxia University, Yinchuan 750021, China;[Shuifeng Ye] Shanghai Agrobiological Gene Center, Shanghai 201106, China;[Xiang Gao] School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China<&wdkj&>Authors to whom correspondence should be addressed.
通讯机构：
[Xiang Gao; Wenyu Liang] S;School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>School of Life Sciences, Ningxia University, Yinchuan 750021, China<&wdkj&>Authors to whom correspondence should be addressed.
摘要：
Nostoc flagelliforme, a filamentous nitrogen-fixing cyanobacterium, is widely distributed in arid steppes of the west and northwestern parts of China. However, as a food delicacy this species has been overexploited from 1970 to 2000. Moreover, overgrazing, land reclamation and the removal of medicinal herbs have caused severely reduced vegetation coverage there. In this communication, a badly damaged but slowly rehabilitating N. flagelliforme-inhibiting steppe is described, and the rehabilitation of desertified steppes by the renewed growth of N. flagelliforme is proposed. The restoration of this dominant nitrogen supplier would be an ecologically sustainable solution for supplementing current measures already taken in the desertified regions. In addition, a goal of 50%–60% vegetation coverage is proposed by the N. flagelliforme restoration.
作者机构：
[Qiu, Bao-Sheng; Gao, Xiang; Gong, Huan; Chen, Bo-Xia; Luo, Hong-Yi; Cui, Li-Juan; Zhang, Zhong-Chun; Ai, Wen-Li] Cent China Normal Univ, Sch Life Sci, Wuhan, Peoples R China.;[Qiu, Bao-Sheng; Gao, Xiang; Gong, Huan; Chen, Bo-Xia; Luo, Hong-Yi; Cui, Li-Juan; Zhang, Zhong-Chun; Ai, Wen-Li] Cent China Normal Univ, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan, Peoples R China.
通讯机构：
[Qiu, Bao-Sheng] C;Cent China Normal Univ, Sch Life Sci, Wuhan, Peoples R China.;Cent China Normal Univ, Hubei Key Lab Genet Regulat & Integrat Biol, Wuhan, Peoples R China.
关键词：
Abiotic stress;Gene transfer;Heavy metal hyperaccumulator;ROS signaling;Sedum alfredii;Superoxide dismutase
摘要：
Transgenic research was preformed by transferring a cyanobacterial (Nostoc flagelliforme) iron superoxide dismutase gene (NfFeSOD) into heavy metal hyperaccumulator Sedum alfredii via Agrobacterium-mediated method. Beyond expectation, NfFeSOD-overexpressing S. alfredii plants exhibited profound impairments, including plant growth retardation, abnormal root architecture, and reduced leaf greenness, photosynthetic efficiency and metal accumulation efficiency. Although transgenic plants appeared physiologically sensitive to high temperature, a higher relative biomass growth was still observed under long-term high temperature and osmotic stresses. Further investigation found that reactive oxygen species (ROS) homeostasis of transgenic plants was significantly affected, being similar to 50 % reduction of H2O2 level relative to wild-type plants. Gene transcription including ROS responsive genes was overall attenuated in transgenic plants, being more significant at normal temperature than at high temperature. In addition, ascorbate peroxidase (APX) activity was increased nearly twofolds in transgenic plants as compared to wild-type control. It may be inferred that ectopic NfFeSOD overexpression gives rise to a substantial increase of APX activity and leads to a sharp reduction of H2O2 level, thus impairing basal ROS signaling and plant growth. Specific genetic background of S. alfredii may be responsible for this sharp reduction of H2O2 level induced by NfFeSOD overexpression. S. alfredii plant has acclimated to elevated levels of ROS induced by heavy metals in native habitats and should require high ROS levels for basal signaling. We thus suppose that a sustained disturbance of high basal ROS signaling in metal hyperaccumulators may instead incur very sensitive response and thus result in profound growth impairments.
作者机构：
[Shuifeng Ye] a Shanghai Agrobiological Gene Center;[Shuifeng Ye] Shanghai , China;[Xiang Gao] b School of Life Sciences;[Xiang Gao] Central China Normal University;[Xiang Gao] Wuhan , China
通讯机构：
[Shuifeng Ye; Xiang Gao] S;Shanghai Agrobiological Gene Center<&wdkj&>Shanghai, China<&wdkj&>School of Life Sciences<&wdkj&>Central China Normal University<&wdkj&>Wuhan, China
摘要：
Genetically engineered (GE) crops with resistance to environmental stresses are one of the most important solutions for future food security. Numerous genes associated to plant stress resistance have been identified and characterized. However, the current reality is that only a few transgenic crops expressing prokaryotic genes are successfully applied in field conditions. These few prokaryotic genes include Agrobacterium strain CP4 EPSPS gene, Bacillus thuringiensis Cry1Ab gene and a bacterial chaperonin gene. Thus, the excavation of potentially critical genes still remains an arduous task for crop engineering. Terrestrial macroscopic cyanobacteria, Nostoc commune and Nostoc flagelliforme, which exhibit extreme resistance to desiccation stress, may serve as new prokaryotic bioresources for excavating critical genes. Recently, their marker gene wspA was heterologously expressed in Arabidopsis plant and the transgenics exhibited more flourishing root systems than wild-type plants under osmotic stress condition. In addition, some new genes associated with drought response and adaptation in N. flagelliforme are being uncovered by our ongoing RNA-seq analysis. Although the relevant work about the terrestrial macroscopic cyanobacteria is still underway, we believe that the prospect of excavating their critical genes for application in GE crops is quite optimistic.
摘要：
<jats:title>Summary</jats:title><jats:p><jats:styled-content style="fixed-case"><jats:italic>N</jats:italic></jats:styled-content><jats:italic>ostoc flagelliforme</jats:italic> is a terrestrial edible cyanobacterium that grows in arid and semi‐arid steppes. The continued over‐exploitation in the last century has led to a sharp decline of this resource and a severe deterioration of the steppe ecology. Liquid‐cultured <jats:styled-content style="fixed-case"><jats:italic>N</jats:italic></jats:styled-content><jats:italic>. flagelliforme</jats:italic> serves as promising algal ‘seeds’ for resource restoration. In this study, macroscopic (or visible) aquatic‐living colonies (<jats:styled-content style="fixed-case">MaACs</jats:styled-content>) of <jats:styled-content style="fixed-case"><jats:italic>N</jats:italic></jats:styled-content><jats:italic>. flagelliforme</jats:italic> were developed under weak light and high nitrogen conditions. In a 24 day shake‐flask culture, <jats:styled-content style="fixed-case">MaACs</jats:styled-content> were propagated by about 4.5‐fold in biomass without loss of their macro‐morphology; at the same time, the addition of weak <jats:styled-content style="fixed-case">UV</jats:styled-content>‐<jats:styled-content style="fixed-case">B</jats:styled-content> treatment resulted in slightly bigger <jats:styled-content style="fixed-case">MaACs</jats:styled-content>. Polyvinylpyrrolidone (<jats:styled-content style="fixed-case">PVP</jats:styled-content>) k30, a water‐soluble polymer, was used to generate the coating around <jats:styled-content style="fixed-case">MaACs</jats:styled-content>, and after full desiccation, the coated <jats:styled-content style="fixed-case">MaACs</jats:styled-content> could recover their photosynthetic physiological activity when rehydrated, with 4% <jats:styled-content style="fixed-case">PVP</jats:styled-content> k30 for coating being most effective. In contrast, <jats:styled-content style="fixed-case">PVP</jats:styled-content> k30‐coated microscopic aquatic‐living colonies of <jats:styled-content style="fixed-case"><jats:italic>N</jats:italic></jats:styled-content><jats:italic>. flagelliforme</jats:italic> and non‐coated <jats:styled-content style="fixed-case">MaACs</jats:styled-content> showed no resistance to full desiccation. The macroscopic morphology or structure of <jats:styled-content style="fixed-case">MaACs</jats:styled-content> should be crucial for the formation of protection by <jats:styled-content style="fixed-case">PVP</jats:styled-content> k30 coating. <jats:styled-content style="fixed-case">PVP</jats:styled-content> k30‐coated <jats:styled-content style="fixed-case">MaACs</jats:styled-content> were more approaching to actual application for resource restoration.</jats:p>
摘要：
The terrestrial macroscopic cyanobacterium Nostoc commune exhibits remarkable resistance to desiccation stress. This species synthesizes abundant acidic water stress protein (WSPA) in cells upon desiccation and secretes it into the extracellular polysaccharide sheath upon rehydration. However, our knowledge about its cellular role in stress resistance is still rather limited. In this paper, we first revealed that WSPA also occurred in two other macroscopic cyanobacteria Nostoc flagelliforme and Nostoc sphaeroides, but it is more abundant in N. commune. The N. commune wspa1 gene was then heterologously expressed in Arabidopsis thaliana. Phenotypic observation found that WSPA1 conferred increased tolerance to osmotic stress in transgenic plants. The physiological indexes such as relative electrolyte leakage, malondialdehyde, proline accumulation and the maximal quantum efficiency of Photosystem II, were also improved in transgenic plants upon osmotic stress, compared to wild types. In addition, GFP fluorescence analysis of eGFP::wspa1 transgenic plant showed that WSPA1 was localized in the cytoplasm. Therefore, the role of WSPA revealed by this study mainly represented its intracellular function. In general, our research suggested that WSPA may act as a stress protein and involve cellular osmotic stress resistance.
摘要：
Nostoc flagelliforme is a terrestrial drought-resistant cyanobacterium whose potential genetic resources remain poorly explored. In this study, we evaluated the potential stress regulation-associated functions of three candidate genes, drnf3, 5, and 9. Transcriptional analysis showed that these three genes were stress responsive. Their functions were evaluated by introducing them into the expression vector pET28a and Escherichia coli strain BL21. Each of the three transformed strains exhibited enhanced cell growth in osmotic and salt stress conditions when compared to a control strain transformed with the empty vector. Three transformed strains also showed enhanced cell growth under normal condition. These results imply that increased abiotic stress resistance may be related to the basal functions of these three genes in promoting cell growth. Their actual molecular mechanisms of stress regulation remain to be explored. However, from an applied point of view, they would serve as important candidate genes in the development of transgenic industrial strains that need to be resistant to osmotic or salt stress.
作者机构：
[AI; GAO; QIU; CHEN; GONG] Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Sciences, Central China Normal University, Wuhan, 430079, China
通讯机构：
[Xiang Gao] H;Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Sciences, Central China Normal University, Wuhan, China
关键词：
heavy metals;hyperaccummulator;lake water;phytoremediation;Sedum alfredii
摘要：
Sedum alfredii Hance is a terrestrial zinc/cadmium (Zn/Cd)-hyperaccumulating and lead (Pb)-accumulating plant. Previous studies on S. alfredii were mostly focused on its physiological mechanism of heavy metal uptake and the application in phytoextraction of metals from contaminated soils. In this study, we evaluated the application potential of S. alfredii in the cleanup of heavy metals from contaminated lake water. Our research revealed that changing pH in lake water would not make particular difference on the final accumulation amount of heavy metals, because the acidic water environment negatively affected plant growth compared with the neutral and alkaline environments, but was more conducive for heavy metal absorption and accumulation. In addition, S. alfredii showed an increase of approximately 2.2-fold in dry weight (DW) when cultured with lake water for 25 d. At the same time, it accumulated approximately 5.0 mg/kg DWof Cd and 41.4 mg/kg DWof Pb. The absorption of heavy metals was highly effective during the first 10 d of culture. Also, the quality of lake water was greatly improved after only 2-d cleanup by S. alfredii. In general, this hyperaccumulator exhibits great potential for application in the cleanup of heavy metals-polluted waters.
作者机构：
[朱德锐; 龙启福; 刘建; 沈国平; 高翔] Medical College, Qinghai University, Xining 810016, China;[刘建] College of Life Sciences, Central China Normal University, Wuhan 430079, China;[刘德立] Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Wuhan 430079, China
通讯机构：
[Zhu, D.] M;Medical College, Qinghai University, China
