Xiangbin Xu

Hangzhou Normal University, Hang-hsien, Zhejiang Sheng, China

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Publications (12)26.96 Total impact

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    ABSTRACT: Grain production of rice (Oryza sativa L.) is a top priority in ensuring food security for human beings. One of the approaches to increase yield is to delay leaf senescence and to extend the available time for photosynthesis. MicroRNAs (miRNAs) are key regulators of aging and cellular senescence in eukaryotes. Here, to help understand their biological role in rice leaf senescence, we report identification of miRNAs and their putative target genes by deep sequencing of six small RNA libraries, six RNA-seq libraries and two degradome libraries from the leaves of two super hybrid rice, Nei-2-You 6 (N2Y6, age-resistant rice) and Liang-You-Pei 9 (LYP9, age-sensitive rice). In total 372 known miRNAs, 162 miRNA candidates and 1145 targets were identified. Compared with the expression of miRNAs in the leaves of LYP9, the numbers of miRNAs up-regulated and down-regulated in the leaves of N2Y6 were 47 and 30 at early stage of grain-filling, 21 and 17 at the middle stage, and 11 and 37 at the late stage, respectively. Six miRNA families, osa-miR159, osa-miR160 osa-miR164, osa-miR167, osa-miR172 and osa-miR1848, targeting the genes encoding APETALA2 (AP2), zinc finger proteins, salicylic acid-induced protein 19 (SIP19), auxin response factors (ARF) and NAC transcription factors, respectively, were found to be involved in leaf senescence through phytohormone signaling pathways. These results provided valuable information for understanding the miRNA-mediated leaf senescence of rice, and offered an important foundation for rice breeding.
    PLoS ONE 01/2014; 9(12):e114313. · 3.53 Impact Factor
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    ABSTRACT: Rice is one of the most important staple crops. During the growth season, rice plants are inevitably subjected to numerous stresses, among which heavy metal stress represented by cadmium contamination not only hindering the yield of rice but also affecting the food safety by Cd accumulating in rice grains. The mechanism of Cd accumulation in rice grains has not been well elucidated. In this study, we compare the proteomic difference between two genotypes with different Cd accumulation ability in grains. Verification of differentially expressed protein-encoding genes was analyzing by quantitative PCR (QPCR) and reanalysis of microarray expression data. Forty-seven proteins in total were successfully identified through proteomic screening. GO and KEGG enrichment analysis showed Cd accumulation triggered stress-related pathways in the cells, and strongly affecting metabolic pathways. Many proteins associated with nutrient reservoir and starch-related enzyme were identified in this study suggesting that a considerably damage on grain quality was caused. The results also implied stress response was initiated by the abnormal cells and the transmission of signals may mediated by reactive oxygen species (ROS). Our research will provide new insights into Cd accumulation in rice grain under Cd stress.
    Journal of Hazardous Materials. 01/2014; 280:269–278.
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    ABSTRACT: Salvia miltiorrhiza is one of the most popular traditional medicinal herbs in Asian nations. Its dried root contains a number of tanshinones, protocatechuic aldehyde, salvianolic acid B and rosmarinic, and is used for the treatment of various diseases. The finding of microRNAs (miRNAs) and their target genes will help understand their biological role on the biosynthesis of tanshinones in S. miltiorrhiza. In the present study, a total of 452 known miRNAs corresponding to 589 precursor miRNAs (pre-miRNAs), and 40 novel miRNAs corresponding to 24 pre-miRNAs were identified in different tissues of S. miltiorrhiza by high-throughput sequencing, respectively. Among them, 62 miRNAs express only in root, 95 miRNAs express only in stem, 19 miRNAs express only in leaf, and 71 miRNAs express only in flower, respectively. By the degradome analysis, 69 targets potentially cleaved by 25 miRNAs were identified. Among them, acetyl-CoA C-acetyltransferase was cleaved by miR5072, and involved in the biosynthesis of tanshinones. This study provided valuable information for understanding the tissue-specific expression patterns of miRNAs in S. miltiorrhiza, and offered a foundation for future studies of the miRNA-mediated biosynthesis of tanshinones.
    PLoS ONE 01/2014; 9(11):e111679. · 3.53 Impact Factor
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    ABSTRACT: In non-climacteric fruits, the respiratory increase is absent and no phytohormone is appearing to be critical for their ripening process. They must remain on the parent plant to enable full ripening and be picked at or near the fully ripe stage to obtain the best eating quality. However, huge losses often occur for their quick post-harvest senescence. To understanding the complex mechanism of non-climacteric fruits post-harvest senescence, we constructed two small RNA libraries and one degradome from strawberry fruit stored at 20°C for 0 and 24 h. A total of 88 known and 1224 new candidatemiRNAs, and 103 targets cleaved by 19 known miRNAs families and 55 new candidatemiRNAs were obtained. These targets were associated with development, metabolism, defense response, signaling transduction and transcriptional regulation. Among them, 14 targets, including NAC transcription factor, Auxin response factors (ARF) and Myb transcription factors, cleaved by 6 known miRNA families and 6 predicted candidates, were found to be involved in regulating fruit senescence. The present study provided valuable information for understanding the quick senescence of strawberry fruit, and offered a foundation for studying the miRNA-mediated senescence of non-climacteric fruits.
    PLoS ONE 01/2013; 8(8):e70959. · 3.53 Impact Factor
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    ABSTRACT: The effects of low temperature on endogenous nitric oxide (NO) generation and the role of endogenous NO in chilling tolerance of loquat fruit during cold storage were investigated. Low temperature at 1°C triggered a marked increase in endogenous NO levels in loquat fruit during postharvest storage. Pretreatment of fruit with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) not only abolished endogenous NO accumulation but also aggravated chilling injury symptoms in the fruit stored at 1°C and 95% RH. Moreover, the cold-stored fruit in which NO accumulation is abolished by cPTIO exhibited significantly higher membrane permeability, lipid peroxidation, superoxide anion (O2−) production rates and hydrogen peroxide (H2O2) contents than the control fruit. Furthermore, the results show that abolition of endogenous NO accumulation significantly reduced activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) in the fruit during cold storage. Together, our results suggest that cold-induced endogenous NO generation in loquat fruit during postharvest storage plays a critical role in alleviating chilling injury symptoms by affecting the antioxidative defense systems in the fruit.
    Postharvest Biology and Technology - POSTHARVEST BIOL TECHNOL. 01/2012;
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    ABSTRACT: Exposure to ozone induced a rapid increase in the levels of the phytohormone abscisic acid (ABA) and sequentially followed by the enhancement of Taxol production in suspension cell cultures of Taxus chinensis. The observed increases in ABA and Taxol were dependent on the concentration of ozone applied to T. chinensis cell cultures. To examine the role of ABA in ozone-induced Taxol production, we pretreated the cells with ABA biosynthesis inhibitor fluridone to abolish ozone-triggered ABA generation and assayed the effect of fluridone on ozone-induced Taxol production. The results showed that pretreatment of the cells with fluridone not only suppressed the ozone-triggered ABA generation but also blocked the ozone-induced Taxol production. Moreover, our data indicate that the effect of ABA on Taxol production of T. chinensis cell cultures is dose-dependent. Interestingly, the suppression of fluridone on ozone-induced Taxol production was reversed by exogenous application of low dose of ABA, although treatment of low dose ABA alone had no effect on Taxol production of the cells. Together, the data indicated that ozone was an efficient elicitor for improving Taxol production of plant cell cultures. Furthermore, we demonstrated that ABA played critical roles in ozone-induced Taxol production of T. chinensis suspension cell cultures.
    Biotechnology Progress 06/2011; 27(5):1415-20. · 1.85 Impact Factor
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    ABSTRACT: Accumulation of secondary metabolites is one of the common reactions of plants to ozone exposure in nature. To investigate the effect of ozone on the production of desired compounds of plant cell cultures, we assayed hypericin production of Hypericum perforatum suspension cell cultures treated with different doses of ozone at different culture phases. The results show that hypericin contents of the cells treated with 60 to 180 nL L(-1) ozone are significantly higher than those of the control, showing that ozone exposure may stimulate hypericin synthesis. Hypericin production of the cells treated with ozone at exponential phase is higher than that of lag and stationary phase, which suggests that exponential phase cell cultures are more responsive to ozone exposure than lag and stationary phase cells. The highest hypericin production is obtained by the cells exposed to 90 nL L(-1) ozone at late exponential phase for 3 h, being about fourfold of the control. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011.
    Biotechnology Progress 03/2011; · 1.85 Impact Factor
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    ABSTRACT: Secondary metabolite accumulation and nitric oxide (NO) generation are two common responses of plant cells to fungal elicitors, and NO has been reported to play important roles in elicitor-induced secondary metabolite production. However, the source of elicitor-triggered NO generation in plant cells remains largely unknown. To investigate the origin of elicitor-triggered NO, we examined nitrate reductase (NR) activities and the expression levels of NIA1 and NIA2 genes of Camptotheca acuminata cells treated with PB90, a protein elicitor from Phytophthora boehmeriae. The data show that PB90 treatment stimulates NR activity and induces upregulation of NIA1 but does not affect NIA2 expression in the cells. Pretreatment of the cells with NR inhibitors tungstate and Gln abolishes not only the fungal elicitor-triggered NR activities but also the PB90-induced NO generation. Treatment of PB90 enhances camptothecin contents of the cells, suggesting that the fungal elicitor might stimulate camptothecin biosynthesis. Furthermore, application of tungstate and Gln suppresses the fungal elicitor-induced camptothecin accumulation of the cells and the suppression of NR inhibitors on PB90-induced camptothecin production can be reversed by NO via its donor sodium nitroprusside. Together, the results suggest that NIA1 is sensitive to PB90 and the fungal elicitor-induced upregulation of NIA1 may lead to higher NR activity. Furthermore, our data demonstrate that NR is involved in the fungal elicitor-triggered NO generation and the fungal elicitor induces camptothecin production of C. acuminata cells dependently on NR-mediated NO generation.
    Applied Microbiology and Biotechnology 02/2011; 90(3):1073-81. · 3.81 Impact Factor
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    ABSTRACT: The PROMOTION OF CELL SURVIVAL 1 (PCS1) gene, encoding an aspartic protease, has an important role in determining the fate of cells in embryonic development and reproduction processes in Arabidopsis. To explore the potential function of the PCS1 gene in generating reproductive sterility, we placed the PCS1 gene under the control of an 1,869-bp nucleotide sequence from the 3′ end of the second intron (AG-I) of Arabidopsis AGAMOUS and CaMV 35S (–60) minimal promoter [AG-I-35S (–60)::PCS1], and introduced it into tobacco. RT–PCR results demonstrated that the PCS1 gene driven by AG-I-35S (–60) chimeric promoter was expressed only in anthers and carpels in the reproductive tissues of transgenic tobacco. Compared to wild-type plants, all AG-I-35S (–60) and AG-I-35S (–60)::PCS1 transgenic lines showed a normal phenotype throughout the vegetative growth phase. However, during the reproductive stage, most AG-I-35S (–60)::PCS1 transgenic plant anthers displayed delayed dehiscence, failed dehiscence, petalody and hypoplasia, and the pollen grains had different shapes and sizes with a distorted, shrunken, or collapsed morphology. Moreover, three transgenic lines, PCS1-1, PCS1-3 and PCS1-4, showed higher sterility than wild-type and AG-I-35S (–60) transgenic plants, respectively. These results showed that the construct of AG-I-35S (–60)::PCS1 was partially effective at preventing seed set and provided a novel sterility strategy. Keywords AG second intron– Arabidopsis thaliana – PCS1 –Sterility–Tobacco
    Molecular Breeding 01/2011; 27(3):337-346. · 3.25 Impact Factor
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    ABSTRACT: Proton (H(+)) and aluminium (Al(3+)) toxicities are major factors limiting crop production on acid soils, while gamma-aminobutyric acid (GABA) is a non-protein amino acid involved in various stress tolerances in plants. In this study, to determine whether exogenous GABA is functional in alleviating oxidative stress induced by H(+) and Al(3+) toxicities, the antioxidant defence response regulated by GABA was investigated in barley (Hordeum vulgare L.). After 24 h treatments of seedlings under H(+), Al(3+) and combined stresses with and without GABA, morphological and biochemical assays were conducted. It was observed that the inhibition of seedling root elongation caused by Al(3+) and H(+) toxicities was significantly mitigated by GABA. The amount of carbonylated proteins with molecular masses of 14.4-97 kDa was decreased. The activities of antioxidant enzymes were enhanced, the content of malondialdehyde was reduced and the accumulation of reactive oxygen species (ROS), as shown by staining roots with nitroblue tetrazolium, declined in GABA-treated seedlings. GABA can alleviate oxidative damage caused by H(+) and Al(3+) toxicities in barley seedlings by activating antioxidant defence responses and reducing the elevated levels of carbonylated proteins caused by ROS.
    Journal of the Science of Food and Agriculture 07/2010; 90(9):1410-6. · 1.88 Impact Factor
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    ABSTRACT: A 1681 bp PsPR10 promoter was isolated from Pinus strobus and a series of 5'-deletions were fused to the β-glucuronidase (GUS) reporter gene and introduced into tobacco. GUS activity in P796 (-796 to +69) construct transgenic plant roots was similar with that of P1681 and higher than those of the P513 (-513 to +69) and P323 (-323 to +69) transgenic plants. Moreover, the abiotic stresses of NaCl, PEG 6000 and mannitol, and salicylic acid (SA), abscisic acid (ABA) and jasmonic acid (JA) induced higher GUS activity in the roots of P796 transgenic tobacco. This study provides a potential inducible root-specific promoter for transgenic plants.
    Biotechnology Letters 05/2010; 32(10):1533-9. · 1.85 Impact Factor
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    ABSTRACT: The function of cytosolic AtHsp90.3 was characterized by complementing the Saccharomyces cerevisiae endogenous Hsp90 genes and overexpressing it in Arabidopsis thaliana. Though AtHsp90.3 supported the yeast growth under heat stress, in Arabidopsis, compared to the wild type, the transgenic plants overexpressing cytosolic AtHsp90.3 were more sensitive to heat stress with a lower germination rate and higher mortality but and more tolerant to high Ca(2+). Transcriptional expression of heat stress transcription factors, AtHsfA1d, AtHsfA7a and AtHsfB1, and two Hsps, AtHsp101 and AtHsp17, was delayed by constitutive overexpression of cytosolic AtHsp90.3 under heat stress. These results indicate that overexpressing AtHsp90.3 impaired plant tolerance to heat stress and proper homeostasis of Hsp90 was critical for cellular stress response and/or tolerance in plants.
    Biotechnology Letters 03/2010; 32(7):979-87. · 1.85 Impact Factor