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1.
Rodrigues SP Ventura JA Aguilar C Nakayasu ES Choi H Sobreira TJ Nohara LL Wermelinger LS Almeida IC Zingali RB Fernandes PM 《Journal of Proteomics》2012,75(11):3191-3198
Papaya meleira virus (PMeV) is so far the only described laticifer-infecting virus, the causal agent of papaya (Carica papaya L.) sticky disease. The effects of PMeV on the laticifers' regulatory network were addressed here through the proteomic analysis of papaya latex. Using both 1-DE- and 1D-LC-ESI-MS/MS, 160 unique papaya latex proteins were identified, representing 122 new proteins in the latex of this plant. Quantitative analysis by normalized spectral counting revealed 10 down-regulated proteins in the latex of diseased plants, 9 cysteine proteases (chymopapain) and 1 latex serine proteinase inhibitor. A repression of papaya latex proteolytic activity during PMeV infection was hypothesized. This was further confirmed by enzymatic assays that showed a reduction of cysteine-protease-associated proteolytic activity in the diseased papaya latex. These findings are discussed in the context of plant responses against pathogens and may greatly contribute to understand the roles of laticifers in plant stress responses. 相似文献
2.
Paolla M. V. Abreu Clicia G. Gaspar David S. Buss José A. Ventura Paulo C. G. Ferreira Patricia M. B. Fernandes 《PloS one》2014,9(7)
MicroRNAs are implicated in the response to biotic stresses. Papaya meleira virus (PMeV) is the causal agent of sticky disease, a commercially important pathology in papaya for which there are currently no resistant varieties. PMeV has a number of unusual features, such as residence in the laticifers of infected plants, and the response of the papaya to PMeV infection is not well understood. The protein levels of 20S proteasome subunits increase during PMeV infection, suggesting that proteolysis could be an important aspect of the plant defense response mechanism. To date, 10,598 plant microRNAs have been identified in the Plant miRNAs Database, but only two, miR162 and miR403, are from papaya. In this study, known plant microRNA sequences were used to search for potential microRNAs in the papaya genome. A total of 462 microRNAs, representing 72 microRNA families, were identified. The expression of 11 microRNAs, whose targets are involved in 20S and 26S proteasomal degradation and in other stress response pathways, was compared by real-time PCR in healthy and infected papaya leaf tissue. We found that the expression of miRNAs involved in proteasomal degradation increased in response to very low levels of PMeV titre and decreased as the viral titre increased. In contrast, miRNAs implicated in the plant response to biotic stress decreased their expression at very low level of PMeV and increased at high PMeV levels. Corroborating with this results, analysed target genes for this miRNAs had their expression modulated in a dependent manner. This study represents a comprehensive identification of conserved miRNAs inpapaya. The data presented here might help to complement the available molecular and genomic tools for the study of papaya. The differential expression of some miRNAs and identifying their target genes will be helpful for understanding the regulation and interaction of PMeV and papaya. 相似文献
3.
Rodrigues SP Ventura JA Aguilar C Nakayasu ES Almeida IC Fernandes PM Zingali RB 《Proteomics》2011,11(13):2592-2602
Papaya (Carica papaya L.) hosts the only described laticifer-infecting virus (Papaya meleira virus, PMeV), which is the causal agent of papaya sticky disease. To understand the systemic effects of PMeV in papaya, we conducted a comprehensive proteomic analysis of leaf samples from healthy and diseased plants grown under field conditions. First, a reference 2-DE map was established for proteins from healthy samples. A total of 486 reproducible spots were identified, and MALDI-TOF-MS/MS data identified 275 proteins accounting for 159 distinct proteins from 231 spots that were annotated. Second, the differential expression of proteins from healthy and diseased leaves was determined through parallel experiments, using 2-DE and DIGE followed by MALDI-TOF-MS/MS and LC-IonTrap-MS/MS, respectively. Conventional 2-DE analysis revealed 75 differentially expressed proteins. Of those, 48 proteins were identified, with 26 being upregulated (U) and 22 downregulated (D). In general, metabolism-related proteins were downregulated, and stress-responsive proteins were upregulated. This expression pattern was corroborated by the results of the DIGE analysis, which identified 79 differentially expressed proteins, with 23 identified (17 U and 6 D). Calreticulin and the proteasome subunits 20S and RPT5a were shown to be upregulated during infection by both 2-DE and DIGE analyses. These data may help shed light on plant responses against stresses and viral infections. 相似文献
4.
Effects of exogenous H2O2 application on vinblastine (VBL) and its precursors, vindoline (VIN), catharanthine (CAT) and α-3′,4′-anhydrovinblastine
(AVBL), were measured in Catharanthus roseus seedlings in order to explore possible correlation of VBL formation with oxidative stress. VBL accumulation has previously
been shown to be regulated by an in vitro H2O2-dependent peroxidase (POD)-like synthase. Experimental exposure of plants to different concentrations of H2O2 showed that endogenous H2O2 and alkaloid concentrations in leaves were positively elevated. The time-course variations of alkaloid concentrations and
redox state, reflected by the concentrations of H2O2, ascorbic acid (AA), oxidative product of glutathione (GSSG) and POD activity, were significantly altered due to H2O2 application. The further correlation analysis between alkaloids and redox status indicated that VBL production was tightly
correlated with redox status. These results provide a new link between VBL metabolisms and redox state in C. roseus. 相似文献
5.
Frick S Chitty JA Kramell R Schmidt J Allen RS Larkin PJ Kutchan TM 《Transgenic research》2004,13(6):607-613
The berberine bridge enzyme cDNA bbe from Papaver somniferumL. was transformed in antisense orientation into seedling explants of the industrial elite line C048-6-14-64. In this way, 84 phenotypically normal T0 plants derived from embryogenic callus cultures were produced. The selfed progeny of these 84 plants yielded several T1 plants with an altered alkaloid profile. One of these plants T1-47, and its siblings T2-1.2 and T2-1.5 are the subject of the present work. The transformation of these plants was evaluated by PCR, and northern and Southern hybridisation. The transgenic plants contained one additional copy of the transgene. The alkaloid content in latex and roots was determined with HPLC and LC-MS. We observed an increased concentration of several pathway intermediates from all biosynthetic branches, e.g., reticuline, laudanine, laudanosine, dehydroreticuline, salutaridine and (S)-scoulerine. The transformation altered the ratio of morphinan and tetrahydrobenzylisoquinoline alkaloids in latex but not the benzophenanthridine alkaloids in roots. The altered alkaloid profile is heritable at least to the T2 generation. These results are the first example of metabolic engineering of the alkaloid pathways in opium poppy and, to our knowledge, the first time that an alkaloid biosynthetic gene has been transformed into the native species, followed by regeneration into a mature plant to enable analyses of the effect of the transgene on metabolism over several generations. 相似文献
6.
A.C. Carib dos Santos J.A.L. Sena S.C. Santos C.V. Dias C.P. Pirovani C. Pungartnik R.R. Valle J.C.M. Cascardo M. Vincentz 《Fungal genetics and biology : FG & B》2009,46(11):825-836
The genome sequence of the hemibiotrophic fungus Moniliophthora perniciosa revealed genes possibly participating in the RNAi machinery. Therefore, studies were performed in order to investigate the efficiency of gene silencing by dsRNA. We showed that the reporter gfp gene stably introduced into the fungus genome can be silenced by transfection of in vitro synthesized gfpdsRNA. In addition, successful dsRNA-induced silencing of endogenous genes coding for hydrophobins and a peroxiredoxin were also achieved. All genes showed a silencing efficiency ranging from 18% to 98% when compared to controls even 28 d after dsRNA treatment, suggesting systemic silencing. Reduction of GFP fluorescence, peroxidase activity levels and survival responses to H2O2 were consistent with the reduction of GFP and peroxidase mRNA levels, respectively. dsRNA transformation of M. perniciosa is shown here to efficiently promote genetic knockdown and can thus be used to assess gene function in this pathogen. 相似文献
7.
Xiuli Hu Wei Wang Chunqi Li Jianhua Zhang Fan Lin Aying Zhang Mingyi Jiang 《Plant Growth Regulation》2008,55(3):183-198
Here we examined whether Ca2+/Calmodulin (CaM) is involved in abscisic acid (ABA)-induced antioxidant defense and the possible relationship between CaM
and H2O2 in ABA signaling in leaves of maize (Zea mays L.) plants exposed to water stress. An ABA-deficient mutant vp5 and its wild type were used for the experimentation. We found that water stress enhanced significantly the contents of CaM
and H2O2, and the activities of chloroplastic and cytosolic superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione
reductase (GR), and the gene expressions of the CaM1, cAPX, GR1 and SOD4 in leaves of wild-type maize. However, the increases mentioned above were almost arrested in vp5 plants and in the wild-type plants pretreated with ABA biosynthesis inhibitor tungstate (T), suggesting that ABA is required
for water stress-induced H2O2 production, the enhancement of CaM content and antioxidant defense. Besides, we showed that the up-regulation of water stress-induced
antioxidant defense was almost completely blocked by pretreatment with Ca2+ inhibitors, CaM antagonists and reactive oxygen (ROS) manipulators. Moreover, the analysis of time course of CaM and H2O2 production under water stress showed that the increase in CaM content preceded that of H2O2. These results suggested that Ca2+/CaM and H2O2 were involved in the ABA-induced antioxidant defense under water stress, and the increases of Ca2+/CaM contents triggered H2O2 production, which inversely affected the contents of CaM. Thus, a cross-talk between Ca2+/CaM and H2O2 may play a pivotal role in the ABA signaling. 相似文献
8.
Starch biosynthesis and degradation was studied in seedlings and mature plants of Euphorbia heterophylla L. and E. myrsinites L. Mature embryos, which lack starch grains in the non-articulated laticifers, develop into seedlings that accumulate starch rapidly when grown either in the light or the dark. Starch accumulation in laticifers of dark-grown seedlings was ca. 47 and 43% of total starch in light-grown controls in E. heterophylla and E. myrsinites, respectively. In light-grown seedlings, starch was present in laticifers as well as parenchyma of stems and leaves, whereas in dark-grown seedlings starch synthesis was almost exclusively limited to laticifers. In 7-month-old plants placed into total darkness, the starch in chyma was depleted within 6 d, whereas starch in laticifers was not mobilized. The starch content of latex in plants during development of floral primordia, flowering, and subsequent fruit formation remained rather constant. The results indicate that laticifers in seedlings divert embryonal storage reserves to synthesize starch even under stress conditions (darkness) in contrast to other cells, and that starch accumulated in laticifers does not serve as a metabolic reserve. The laticifer in Euphorbia functions in the accumulation and storage of secondary metabolites yet retains the capacity to produce, but not utilize starch, a primary metabolite. 相似文献
9.
Opium poppy, Papaver somniferum, is cultivated for its alkaloid-rich latex. Tyrosine decarboxylase (TyDC) is the first enzyme in poppy alkaloid biosynthesis and is encoded by a small gene family. A 2,060-bp promoter fragment of TyDC5 was translationally fused to the #-glucuronidase (GUS) reporter gene and introduced into poppy and tobacco (Nicotiana tabacum). Transgenic seedlings were stained for GUS activity which localized to the xylem parenchyma in the shoots of poppy and tobacco. Roots of both species had similar expression patterns with staining in the vascular cylinder surrounding the xylem. No staining was observed in poppy laticifers suggesting that other TyDC genes may be expressed in latex or that alkaloid precursors are supplied to laticifers by adjacent cells. 相似文献
10.
Tze Soo Lim Thiruvetipuram Rajam Chitra Boon Hui Tay Eng Chong Pua Hao Yu 《Journal of Plant Growth Regulation》2008,27(2):99-109
Superoxide dismutases (SODs) are ubiquitous metalloenzymes that catalyze the dismutation of superoxide radicals (O2-) to molecular oxygen (O2) and hydrogen peroxide (H2O2). In this study we characterized an Arabidopsis thaliana CuZnSOD (CSD1), a close ortholog of a previously identified Brassica juncea CuZnSOD (MSOD1). CSD1 and other two homologs CSD2 and CSD3 were spatially regulated in Arabidopsis, and CSD1 exhibited distinct expression patterns in response to different stress treatments. To investigate the in vivo function of SOD, transgenic Arabidopsis plants, expressing sense and antisense MSOD1 RNAs, were generated and those with altered SOD activity were selected for further characterization. Although SOD transgenic
plants exhibited normal phenotypes, the shoot regeneration response in transgenic explants was significantly affected by the
modulated SOD activity and the corresponding H2O2 levels. Transgenic explants with downregulated SOD activity were poorly regenerative, whereas those with upregulated SOD
activity were highly regenerative. These results suggest that shoot regeneration in vitro is regulated by the SOD activity. 相似文献
11.
Ros Barceló A 《Planta》2005,220(5):747-756
Lignification in Zinnia elegans L. stems is characterized by a burst in the production of H2O2, the apparent fate of which is to be used by xylem peroxidases for the polymerization of p-hydroxycinnamyl alcohols into lignins. A search for the sites of H2O2 production in the differentiating xylem of Z. elegans stems by the simultaneous use of optical (bright field, polarized light and epi-polarization) and electron-microscope tools revealed that H2O2 is produced on the outer-face of the plasma membrane of both differentiating (living) thin-walled xylem cells and particular (non-lignifying) xylem parenchyma cells. From the production sites it diffuses to the differentiating (secondary cell wall-forming) and differentiated lignifying xylem vessels. H2O2 diffusion occurs mainly through the continuous cell wall space. Both the experimental data and the theoretical calculations suggest that H2O2 diffusion from the sites of production might not limit the rate of xylem cell wall lignification. It can be concluded that H2O2 is produced at the plasma membrane in differentiating (living) thin-walled xylem cells and xylem parenchyma cells associated to xylem vessels, and that it diffuses to adjacent secondary lignifying xylem vessels. The results strongly indicate that non-lignifying xylem parenchyma cells are the source of the H2O2 necessary for the polymerization of cinnamyl alcohols in the secondary cell wall of lignifying xylem vessels. 相似文献
12.
Unicellular green algae have the ability to operate in two distinctly different environments (aerobic and anaerobic), and
to photosynthetically generate molecular hydrogen (H2). A recently developed metabolic protocol in the green alga Chlamydomonas reinhardtii permitted separation of photosynthetic O2-evolution and carbon accumulation from anaerobic consumption of cellular metabolites and concomitant photosynthetic H2-evolution. The H2 evolution process was induced upon sulfate nutrient deprivation of the cells, which reversibly inhibits photosystem-II and
O2-evolution in their chloroplast. In the absence of O2, and in order to generate ATP, green algae resorted to anaerobic photosynthetic metabolism, evolved H2 in the light and consumed endogenous substrate. This study summarizes recent advances on green algal hydrogen metabolism
and discusses avenues of research for the further development of this method. Included is the mechanism of a substantial tenfold
starch accumulation in the cells, observed promptly upon S-deprivation, and the regulated starch and protein catabolism during
the subsequent H2-evolution. Also discussed is the function of a chloroplast envelope-localized sulfate permease, and the photosynthesis–respiration
relationship in green algae as potential tools by which to stabilize and enhance H2 metabolism. In addition to potential practical applications of H2, approaches discussed in this work are beginning to address the biochemistry of anaerobic H2 photoproduction, its genes, proteins, regulation, and communication with other metabolic pathways in microalgae. Photosynthetic
H2 production by green algae may hold the promise of generating a renewable fuel from nature’s most plentiful resources, sunlight
and water. The process potentially concerns global warming and the question of energy supply and demand. 相似文献
13.
The histochemical and cytochemical localization of abscisic acid (ABA)-induced H2O2 production in leaves of maize (Zea mays L.) plants were examined, using 3,3-diaminobenzidine (DAB) and CeCl3 staining, respectively, and the relationship between ABA-induced H2O2 production and ABA-induced subcellular activities of antioxidant enzymes was studied. H2O2 generated in response to ABA treatment was detected within 0.5 h in major veins of the leaves and maximized at about 2–4 h. In mesophyll and bundle sheath cells, ABA-induced H2O2 accumulation was observed only in apoplast, and the greatest accumulation occurred in the walls of mesophyll cells facing large intercellular spaces. Meanwhile, ABA treatment led to a significant increase in the activities of the leaf chloroplastic and cytosolic antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), and pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI), the O
2
−
scavenger Tiron and the H2O2 scavenger dimethylthiourea (DMTU) almost completely arrested the increase in the activities of these antioxidant enzymes. Our results indicate that the accumulation of apoplastic H2O2 is involved in the induction of the chloroplastic and cytosolic antioxidant enzymes. Moreover, an oxidative stress induced by paraquat (PQ), which generates O
2
−
and then H2O2 in chloroplasts, also up-regulated the activities of the chloroplastic and cytosolic antioxidant enzymes, and the up-regulation was blocked by the pretreatment with Tiron and DMTU. These data suggest that H2O2 produced at a specific cellular site could coordinate the activities of antioxidant enzymes in different subcellular compartments. 相似文献
14.
Evidence for the participation of reactive oxygen species (ROS) and antioxidant systems in ectomycorrhizal (ECM) establishment
is lacking. In this paper, we evaluated ROS production and the activities of superoxide dismutase (SOD) and catalase (CAT)
during the early contact of the ECM fungus Pisolithus tinctorius with the roots of Castanea sativa (chestnut tree). Roots were placed in contact with P. tinctorius mycelia, and ROS production was evaluated by determining the levels of H2O2 and O2
·− during the early stages of fungal contact. Three peaks of H2O2 production were detected, the first two coinciding with O2
·− bursts. The first H2O2 production peak coincided with an increase in SOD activity, whereas CAT activity seemed to be implicated in H2O2 scavenging. P. tinctorius growth was evaluated in the presence of P. tinctorius-elicited C. sativa crude extracts prepared during the early stages of fungal contact. Differential hyphal growth that matched the H2O2 production profile with a delay was detected. The result suggests that during the early stages of ECM establishment, H2O2 results from an inhibition of ROS-scavenging enzymes and plays a role in signalling during symbiotic establishment. 相似文献
15.
The presence of 2 mM bicarbonate in the incubation medium induced stomatal closure in abaxial epidermis of Arabidopsis. Exposure to 2 mM bicarbonate elevated the levels of H2O2 in guard cells within 5 min, as indicated by the fluorescent probe, dichlorofluorescein diacetate (H2DCF-DA). Bicarbonate-induced stomatal closure as well as H2O2 production were restricted by exogenous catalase or diphenylene iodonium (DPI, an inhibitor of NAD(P)H oxidase). The reduced
sensitivity of stomata to bicarbonate and H2O2 production in homozygous atrbohD/F double mutant of Arabidopsis confirmed that NADP(H) oxidase is involved during bicarbonate induced ROS production in guard cells. The production of H2O2 was quicker and greater with ABA than that with bicarbonate. Such pattern of H2O2 production may be one of the reasons for ABA being more effective than bicarbonate, in promoting stomatal closure. Our results
demonstrate that H2O2 is an essential secondary messenger during bicarbonate induced stomatal closure in Arabidopsis. 相似文献
16.
Tomoki Sando Tatsushi Hayashi Tsuyoshi Takeda Yasunori Akiyama Yoshihisa Nakazawa Eiichiro Fukusaki Akio Kobayashi 《Planta》2009,230(1):215-225
In Hevea brasiliensis, laticifers produce and accumulate rubber particles. Despite observation using histochemical methods, development stage structure
and structures with ceasing functions have rarely been described. Spectral confocal laser scanning microscopy with Nile red
staining simplifies laticifer structure observation in tangential sections while enhancing the resolution. Laticifer and ray
images were extracted from unmixed images and used to monitor changes during growth. A laticifer network structure developed
from increased anastomoses between adjoining laticifers outside of the conducting phloem, but because of increased radial
division and growth of rays, the network structure ruptured and disintegrated. We also investigated immunohistochemical localization
of two rubber particle-associated proteins in the laticifers: small rubber particle protein (SRPP) and rubber elongation factor
(REF). Mature bark test results show that SRPP is localized only in the laticifer layers in the conducting phloem; REF is
localized in all laticifer layers. Because SRPP plays a positive role in rubber biosynthesis, results show that the rubber
biosynthesis capability of laticifers is concentrated where rays and the sieve tube actively transport metabolites. 相似文献
17.
In this study we have investigated whether naturally occurring flavonoid-deficient mutant Red Star of Petunia hybrida is capable of metabolizing H2O2 by invoking other antioxidant enzyme system. We demonstrated that reduced flower pigmentation due to a reduction in the chalcone synthase mRNA expression results in strong H2O2 accumulation accompanied by the induction of a specific set of anionic peroxidase (PRX), serologically-related to main cucumber srPRX. We found correlation between rate of H2O2 accumulation and qualitative, as well as quantitative changes in the srPRX expression which seems to be determined by flower phenotype. In detached flower buds cultured in vitro both abscisic acid and anther extirpation prevented anthocyanin pigmentation, and thus flavonoid biosynthesis, resulting in a marked accumulation of immunoprecipitable srPRX. In contrast, pigmented flowers cultivated under the same conditions did not accumulate corresponding srPRX. The results suggest that a specific set of anionic PRX can substitute for the absence of flavonoid antioxidants. 相似文献
18.
Hydrogen peroxide-induced astaxanthin biosynthesis and catalase activity in Xanthophyllomyces dendrorhous 总被引:1,自引:0,他引:1
Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma) in shake-flask cultures was exposed to 10–20 mmol/L H2O2 at various culture stages, and the astaxanthin production was significantly increased by H2O2 fed at 0 or 24 h (exponential phase), but only slightly at 48 h (near stationary phase). The astaxanthin production was enhanced most significantly with double feeding of 10 mmol/L H2O2 at 0 and 24 h, reaching a cellular content of 1.30 mg/g cell and a volumetric yield of 10.4 mg/L, which were 83 and 65% higher, respectively, than those of the control (0.71 mg/g cell and 6.3 mg/L). The intracellular catalase (CAT) activity was also increased after H2O2 treatment. The increases in CAT and astaxanthin of cells could be detected within 4 h of H2O2 treatment. The increase in the astaxanthin content of cells was concomitant with a notable decrease in the β-carotene content. The older yeast cells at late culture stage (120 h), due perhaps in part to their higher astaxanthin contents, were more tolerant to H2O2 toxicity than the younger cells (24 h). No enhancement of the astaxanthin biosynthesis was attained when H2O2 was added to the yeast culture together with a sufficient amount of exogenous CAT. The results suggest that astaxanthin biosynthesis in X. dendrorhous can be stimulated by H2O2 as an antioxidative response. 相似文献
19.
Chloroplastic LOXs are implicated in the biosynthesis of oxylipins like jasmonic acid and C6 volatiles among others. In this study, we isolated the cDNA of a novel chloroplast-targeted Phaseolus vulgaris LOX, (PvLOX6). This gene is highly induced after wounding, non-host pathogen infection, and by signaling molecules as H2O2, SA, ethylene and MeJA. The phylogenetic analysis of PvLOX6 showed that it is closely related to chloroplast-targeted LOX
from potato (H1) and tomato (TomLOXC); both of them are implicated in the biosynthesis of C6 volatiles. Induction of PvLOX6 mRNA by wounding ethylene and jasmonic acid on the one side, and non-host pathogen, salicylic acid on the other indicates
that common bean uses the same LOX to synthesize oxylipins in response to different stresses.
PvLOX6 accession number: EF196866. 相似文献
20.
Ishibashi Y Yamaguchi H Yuasa T Iwaya-Inoue M Arima S Zheng SH 《Journal of plant physiology》2011,168(13):1562-1567
To ascertain the effect of exogenously applied hydrogen peroxide (H2O2) on drought stress, we examined whether the spraying of soybean leaves with H2O2 would alleviate the symptoms of drought stress. Pre-treatment by spraying leaves with H2O2 delayed foliar wilting caused by drought stress compared to leaves sprayed with distilled water (DW). Additionally, the relative water content of drought-stressed leaves pre-treated with H2O2 was higher than that of leaves pre-treated with DW. Therefore, we analyzed the effect of H2O2 spraying on photosynthetic parameters and on the biosynthesis of oligosaccharides related to water retention in leaves during drought stress. Under conditions of drought stress, the net photosynthetic rate and stomatal conductance of leaves pre-treated with H2O2 were higher than those of leaves pre-treated with DW. In contrast to DW spraying, H2O2 spraying immediately caused an increase in the mRNA levels of d-myo-inositol 3-phosphate synthase 2 (GmMIPS2) and galactinol synthase (GolS), which encode key enzymes for the biosynthesis of oligosaccharides known to help plants tolerate drought stress. In addition, the levels of myo-inositol and galactinol were higher in H2O2-treated leaves than in DW-treated leaves. These results indicated that H2O2 spraying enabled the soybean plant to avoid drought stress through the maintenance of leaf water content, and that this water retention was caused by the promotion of oligosaccharide biosynthesis rather than by rapid stomatal closure. 相似文献