Key Laboratory of Horticultural Plants Growth

Hangzhou, China

Key Laboratory of Horticultural Plants Growth

Hangzhou, China
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Xia X.-J.,Zhejiang University | Xia X.-J.,Key Laboratory of Horticultural Plants Growth | Zhou Y.-H.,Zhejiang University | Shi K.,Zhejiang University | And 4 more authors.
Journal of Experimental Botany | Year: 2015

As a consequence of a sessile lifestyle, plants are continuously exposed to changing environmental conditions and often life-threatening stresses caused by exposure to excessive light, extremes of temperature, limiting nutrient or water availability, and pathogen/insect attack. The flexible coordination of plant growth and development is necessary to optimize vigour and fitness in a changing environment through rapid and appropriate responses to such stresses. The concept that reactive oxygen species (ROS) are versatile signalling molecules in plants that contribute to stress acclimation is well established. This review provides an overview of our current knowledge of how ROS production and signalling are integrated with the action of auxin, brassinosteroids, gibberellins, abscisic acid, ethylene, strigolactones, salicylic acid, and jasmonic acid in the coordinate regulation of plant growth and stress tolerance. We consider the local and systemic crosstalk between ROS and hormonal signalling pathways and identify multiple points of reciprocal control, as well as providing insights into the integration nodes that involve Ca2+-dependent processes and mitogen-activated protein kinase phosphorylation cascades. © The Author 2015.

Zhou J.,Zhejiang University | Xia X.-J.,Zhejiang University | Zhou Y.-H.,Zhejiang University | Shi K.,Zhejiang University | And 4 more authors.
Journal of Experimental Botany | Year: 2014

H2O2 and mitogen-activated protein kinase (MAPK) cascades play important functions in plant stress responses, but their roles in acclimation response remain unclear. This study examined the functions of H 2O2 and MPK1/2 in acclimation-induced cross-tolerance in tomato plants. Mild cold, paraquat, and drought as acclimation stimuli enhanced tolerance to more severe subsequent chilling, photooxidative, and drought stresses. Acclimation-induced cross-tolerance was associated with increased transcript levels of RBOH1 and stress- and defence-related genes, elevated apoplastic H2O2 accumulation, increased activity of NADPH oxidase and antioxidant enzymes, reduced glutathione redox state, and activation of MPK1/2 in tomato. Virus-induced gene silencing of RBOH1, MPK1, and MPK2 or MPK1/2 all compromised acclimation-induced cross-tolerance and associated stress responses. Taken together, these results strongly suggest that acclimation-induced cross-tolerance is largely attributed to RBOH1-dependent H2O2 production at the apoplast, which may subsequently activate MPK1/2 to induce stress responses. © © The Author 2013. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Jiang Y.-P.,Zhejiang University | Cheng F.,Zhejiang University | Zhou Y.-H.,Zhejiang University | Xia X.-J.,Zhejiang University | And 6 more authors.
New Phytologist | Year: 2012

• Brassinosteroids (BRs) play a vital role in plant growth, stress tolerance and productivity. Here, the involvement of BRs in the regulation of CO 2 assimilation and cellular redox homeostasis was studied. • The effects of BRs on CO 2 assimilation were studied in cucumber (Cucumis sativus) through the analysis of the accumulation of H 2O 2 and glutathione and photosynthesis-related enzyme activities using histochemical and cytochemical detection or a spectrophotometric assay, and Rubisco activase (RCA) using western blot analysis and immunogold labeling. • Exogenous BR increased apoplastic H 2O 2 accumulation, the ratio of reduced to oxidized glutathione (GSH:GSSG) and CO 2 assimilation, whereas a BR biosynthetic inhibitor had the opposite effects. BR-induced CO 2 assimilation was decreased by a H 2O 2 scavenger or inhibition of H 2O 2 generation, GSH biosynthesis and the NADPH-generating pentose phosphate pathway. BR-, H 2O 2- or GSH-induced CO 2 assimilation was associated with increased activity of enzymes in the Benson-Calvin cycle. Immunogold labeling and western blotting showed that BR increased the content of RCA and this effect was blocked by inhibitors of redox homeostasis. • These results strongly suggest that BR-induced photosynthesis involves an H 2O 2-mediated increase in the GSH:GSSG ratio, which may positively regulate the synthesis and activation of redox-sensitive enzymes in carbon fixation. © 2012 The Authors New Phytologist. © 2012 New Phytologist Trust.

Nie W.-F.,Zhejiang University | Wang M.-M.,Zhejiang University | Xia X.-J.,Zhejiang University | Zhou Y.-H.,Zhejiang University | And 5 more authors.
Plant, Cell and Environment | Year: 2013

Brassinosteroids (BRs) are involved in the regulation of plant growth, development and stress responses. While the signalling pathways for BR-regulated plant growth and development are well studied, the mechanisms by which BRs regulate plant stress tolerance remain largely unclear. Here we showed that 24-epibrassinolide (EBR), which induced tolerance to oxidative and heat stress in tomato, was also capable of elevating the transcript levels of RBOH1, MPK1 and MPK2, increasing apoplastic H2O2 accumulation, and enhancing activation of MPK1/2. Virus-induced gene silencing of RBOH1, MPK1, MPK2 and MPK1/2 resulted in reduced stress tolerance. Silencing of RBOH1 had no effect on the transcripts of MPK1 and MPK2 but inhibited MPK1/2 activation and H2O2 accumulation. Silencing of either MPK1 or MPK2, on the other hand, reduced RBOH1 transcript, H2O2 accumulation and MPK1/2 activity. BR-induced tolerance and MPK1/2 activation were compromised in RBOH1-, MPK2- and MPK1/2-silenced plants but not in MPK1-silenced plants. These results suggested that MPK2 played a more critical role than MPK1 in EBR-induced apoplastic H2O2 accumulation. RBOH1, MPK1 and MPK2 were involved in the stress tolerance and BR-induced stress tolerance likely involved a positive feedback loop among RBOH1, H2O2and MPK2, leading to sustained apoplastic accumulation of H2O2and related signalling processes. BRs are involved in the regulation of stress responses and the mechanisms remain largely unclear. BRs upregulated transcript of RBOH1, MPK1 and MPK2, apoplastic H2O2 accumulation and activation of MPK1/2. MPK2 played a more critical role than MPK1 in BR-induced apoplastic H2O2 accumulation. BR-induced tolerance and MPK1/2 activation were compromised in RBOH1-, MPK2- and MPK1/2-silenced plants but not in MPK1-silenced plants. BR-induced stress tolerance likely involved a positive feedback loop among RBOH1, H2O2and MPK2, leading to sustained apoplastic accumulation of H2O2and related signaling processes. © 2012 Blackwell Publishing Ltd.

Xu J.-Y.,Zhejiang University | Wu L.-Y.,Zhejiang University | Zheng X.-Q.,Key Laboratory of Horticultural Plants Growth | Lu J.-L.,Zhejiang University | And 2 more authors.
Investigative Ophthalmology and Visual Science | Year: 2010

PURPOSE. To examine the protective effect of green tea polyphenols against ultraviolet B (UVB)-induced damage to retinal pigment epithelial (RPE) cells. METHODS. Green tea polyphenols (GTP) was used to treat RPE cells before or after exposure to UVB. Viability of RPE cells was tested by 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Survivin gene expression was examined by real-time PCR analysis. Ultrastructure of RPE cells was examined by transmission electron microscopy. RESULTS. GTP effectively suppressed the decrease in viability of the UVB stressed RPE cells and the UVB suppression of surviving gene expression level. GTP alleviated mitochondria dysfunction and DNA fragmentation induced by UVB. CONCLUSIONS. GTP protected RPE cells from UVB damage through its increase in the survivin gene expression and its attenuation of mitochondria dysfunction and DNA fragmentation. GTP is a potential candidate for further development as a chemoprotective factor for the primary prevention of agerelated eye diseases such as age-related macular degeneration. © Association for Research in Vision and Ophthalmology.

Ahammed G.J.,Zhejiang University | Yuan H.-L.,Zhejiang University | Ogweno J.O.,Zhejiang University | Zhou Y.-H.,Zhejiang University | And 5 more authors.
Chemosphere | Year: 2012

The present study was carried out to investigate the effects of exogenously applied 24-epibrassinolide (BR) on growth, gas exchange, chlorophyll fluorescence characteristics, lipid peroxidation and antioxidant systems of tomato seedlings grown under different levels (0, 10, 30, 100 and 300μM) of phenanthrene (PHE) and pyrene (PYR) in hydroponics. A concentration-dependent decrease in growth, photosynthetic pigment contents, net photosynthetic rate (Pn), stomatal conductance (Gs), maximal quantum yield of PSII (Fv/Fm), effective quantum yield of PSII (Φ PSII), photochemical quenching coefficient (qP) has been observed following PHE and PYR exposure. By contrast, non-photochemical quenching coefficient (NPQ) was increased. PHE was found to induce higher stress than PYR. However, foliar or root application of BR (50nM and 5nM, respectively) alleviated all those depressions with a sharp improvement in the activity of photosynthetic machinery. The activities of guaicol peroxidase (GPOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) as well as content of malondialdehyde (MDA) were increased in a dose-dependent manner under PHE or PYR treatments. Compared with control the highest increments of GPOD, CAT, APX, GR and MDA by PHE/PYR alone treatments were observed following 300μM concentration, which were 67%, 87%, 53%, 95% and 74% by PHE and 42%, 53%, 30%, 86% and 62% by PYR, respectively. In addition, both reduced glutathione (GSH) and oxidized glutathione (GSSG) were induced by PHE or PYR. Interestingly, BR application in either form further increased enzymatic and non enzymatic antioxidants in tomato roots treated with PHE or PYR. Our results suggest that BR has an anti-stress effect on tomato seedlings contaminated with PHE or PYR and this effect is mainly attributed by increased detoxification activity. © 2011 Elsevier Ltd.

Ahammed G.J.,Zhejiang University | Choudhary S.P.,Zhejiang University | Chen S.,Zhejiang University | Xia X.,Zhejiang University | And 4 more authors.
Journal of Experimental Botany | Year: 2013

Heavy metal pollution often occurs together with organic contaminants. Brassinosteroids (BRs) induce plant tolerance to several abiotic stresses, including phenanthrene (PHE) and cadmium (Cd) stress. However, the role of BRs in PHE+Cd co-contamination-induced stress amelioration is unknown. Here, the interactive effects of PHE, Cd, and 24-epibrassinolide (EBR; a biologically active BR) were investigated in tomato plants. The application of Cd (100 μM) alone was more phytotoxic than PHE applied alone (100 μM); however, their combined application resulted in slightly improved photosynthetic activity and pigment content compared with Cd alone after a 40 d exposure. Accumulation of reactive oxygen species and membrane lipid peroxidation were induced by PHE and/or Cd; however, the differences in effect were insignificant between Cd and PHE+Cd. The foliar application of EBR (0.1 μM) to PHE- and/or Cd-stressed plants alleviated photosynthetic inhibition and oxidative stress by causing enhancement of the activity of the enzymes and related transcript levels of the antioxidant system, secondary metabolism, and the xenobiotic detoxification system. Additionally, PHE and/or Cd residues were significantly decreased in both the leaves and roots after application of EBR, more specifically in PHE+Cd-stressed plants when treated with EBR, indicating a possible improvement in detoxification of these pollutants. The findings thus suggest a potential interaction of EBR and PHE for Cd stress alleviation. These results advocate a positive role for EBR in reducing pollutant residues for food safety and also strengthening phytoremediation. © 2012 The Author. Published by Oxford University Press [on behalf of the Society for Experimental Biology]. All rights reserved.

Xia X.-J.,Zhejiang University | Zhou Y.-H.,Zhejiang University | Ding J.,Zhejiang University | Shi K.,Zhejiang University | And 4 more authors.
New Phytologist | Year: 2011

Brassinosteroids (BRs) are a new class of plant hormones that are essential for plant growth and development. Here, the involvement of BRs in plant systemic tolerance to biotic and abiotic stresses was studied. The effects of 24-epibrassinolide (EBR) on plant stress tolerance were studied through the assessment of symptoms of photooxidative stress by chlorophyll fluorescence imaging pulse amplitude modulation, the analysis of gene expression using quantitative real-time PCR and the measurement of hydrogen peroxide (H2O2) production using a spectrophotometric assay or confocal laser scanning microscopy. Treatment of primary leaves with EBR induced systemic tolerance to photooxidative stress in untreated upper and lower leaves. This was accompanied by the systemic accumulation of H2O2 and the systemic induction of genes associated with stress responses. Foliar treatment of EBR also enhanced root resistance to Fusarium wilt pathogen. Pharmacological study showed that EBR-induced systemic tolerance was dependent on local and systemic H2O2 accumulation. The expression of BR biosynthetic genes was repressed in EBR-treated leaves, but elevated significantly in untreated systemic leaves. Further analysis indicated that EBR-induced systemic induction of BR biosynthetic genes was mediated by systemically elevated H2O2. These results strongly argue that local EBR treatment can activate the continuous production of H2O2, and the autopropagative nature of the reactive oxygen species signal, in turn, mediates EBR-induced systemic tolerance. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Jiang Y.-P.,Zhejiang University | Cheng F.,Zhejiang University | Zhou Y.-H.,Zhejiang University | Xia X.-J.,Zhejiang University | And 3 more authors.
Environmental and Experimental Botany | Year: 2012

CO2 enrichment and brassinosteroids (BR) both have positive impacts on photosynthesis and plant growth. To examine the interactive effect of CO2 enrichment and BR on photosynthesis and plant growth, CO2 assimilation, chlorophyll fluorescence quenching, carbohydrate metabolism, photosynthetic gene transcript and enzyme activity were analyzed in leaves of young plants of cucumber (Cucumis sativus L.) in response to a doubling of growth CO2 level, foliar BR application alone or in combination. Both CO2 elevation and application of BR increased shoot biomass, leaf area, CO2 assimilation, total soluble sugar and starch contents, transcript for photosynthetic gene and activity for enzymes involved in Benson-Calvin cycle but a combination of the two treatments resulted in a more significant effect. Although an elevation of CO2 level had little effects on quantum efficiency of PSII (F{cyrillic}PSII), it significantly increased the electron flux for photosynthetic carbon reduction [Je(PCR)] but decreased electron flux for photorespiratory carbon oxidation [Je(PCO)]. In contrast, BR treatment increased F{cyrillic}PSII and this increase in F{cyrillic}PSII was associated with increased Je(PCR) and Je(PCO). Furthermore, a combined treatment of CO2 elevation and BR resulted in an additive effect on PSII electron flux. However, alternative electron flux was almost unaltered after CO2 enrichment and BR treatment. Thus, short term CO2 elevation did not induce a down-regulation of photosynthesis and there was an additive effect between BR and CO2 on the enhancement of CO2 assimilation in leaves of young cucumber plants. © 2011 Elsevier B.V.

Dong Z.-B.,Zhejiang University | Liang Y.-R.,Zhejiang University | Fan F.-Y.,Zhejiang University | Ye J.-H.,Zhejiang University | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2011

Adsorbent is one of the most important factors for separation efficiency in fixed-bed purification techniques. The adsorption behavior of catechins and caffeine onto polyvinylpolypyrrolidone (PVPP) was investigated by static adsorption tests. The results showed that catechins rather than caffeine were preferred to adsorb onto PVPP since the adsorption selectivity coefficient of total catechins vs caffeine was around 22.5, and that adsorption of catechins could be described by the pseudo-second-order model. Adsorption amount of caffeine onto PVPP in green tea extracts solution was much higher than that in purified caffeine solution although the initial concentration of caffeine was similar in the two solutions, indicating the caffeine might be attached with catechins which were adsorbed by PVPP instead of being adsorbed by PVPP directly. The results also showed that the adsorption capacity of catechins and caffeine decreased with an increase in temperature, and that Freundlich and Langmuir models were both suitable for describing the isothermal adsorption of catechins, but not suitable for caffeine. The predicted maximum monolayer adsorption capacity of total catechins by PVPP was 671.77 mg g-1 at 20 °C, which was significantly higher than that by other reported adsorbents. The thermodynamics analyses indicated that the adsorption of catechins onto PVPP was a spontaneous and exothermic physisorption process, revealing lower temperature was favorable for the adsorption of catechins. Elution tests showed that the desorption rates of catechins and caffeine were higher than 91% and 99% after two elution stages; in detail, almost all of the caffeine could be washed down at the water eluting stage, while catechins could be recovered at the dimethyl sulfoxide/ethanol solution eluting stage. Thus, the PVPP could be used as an excellent alternative adsorbent candidate for separating catechins from crude tea extracts, although some investigations, such as exploring the new eluants with low boiling point and high desorption efficiency, should be conducted furthermore. © 2011 American Chemical Society.

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