[Effects of cortical bone thickness and jaw bone density on pain during implant surgery].

PURPOSE: To investigate the effects of different cortical bone thickness and jaw bone density at implant sites on intraoperative pain during implant surgery. METHODS: One hundred and eighty-seven patients(263 implant sites) who underwent implant placement surgery at the Fourth Affiliated Hospital of Nanchang University from August 2021 to August 2022 were selected to investigate the effects of different cortical bone thickness and jaw bone density HU values at implant sites on the anesthetic effect under local infiltration anesthesia with epinephrine in articaine. SPSS 26.0 software package was used for data analysis. RESULTS: The mean cortical bone thickness at the painful sites[(3.90±1.36) mm] was significantly greater than that at the non-painful sites [(2.24±0.66) mm], and the difference was statistically significant(P＜0.05). The differences in cortical bone thickness in the mandibular anterior, premolar, and molar regions were statistically significant in the comparison of pain and non-pain sites. The mean HU value of bone density was (764.46±239.75) for the painful sites and (612.23±235.31) for the non-painful sites, with significant difference(P＜0.05). The difference was not significant(P＞0.05) when comparing the HU values of painful sites with non-painful sites in the mandibular anterior teeth and anterior molar region, while the difference was significant(P＜0.05) when comparing the HU values of painful sites with non-painful sites in the mandibular molar region. CONCLUSIONS: Sites with large cortical bone thickness have a greater effect on blocking infiltrative anesthetic penetration and are more prone to intraoperative pain during implantation. In the mandibular anterior and premolar regions, the HU value of the implant sites had less effect on infiltrative anesthetic penetration, and the effect was greater in the mandibular molar region, and the implant sites with high HU values in the mandibular molar region were more likely to have intraoperative pain. When the cortical bone thickness in the planned implant site is greater than 3.9 mm and the mean bone density in the mandibular molar region is greater than 665 HU. If there is sufficient safe distance for hole operation, it is recommended to apply mandibular nerve block anesthesia combined with articaine infiltration anesthesia to avoid intraoperative pain and bad surgical experience for the patients.

[Analysis of clinical effects and risk factors of short implant followed up for 7-9 years].

PURPOSE: To evaluate the long-term clinical efficacy of short implants and analyze the influencing factors of the survival rate. METHODS: A total of 178 patients who received implant therapy in the Department of Stomatology, the Fourth Affiliated Hospital of Nanchang University from January 2010 to December 2014 were selected, including 334 short implants of Bicon (implant length ≤6 mm). The basic condition, restoration design, short implant survival rate and complications were observed and analyzed. SPSS 24.0 software package was used for data analysis. RESULTS: The average follow-up time of short implants was 96±17 months. During the observation period, 20 implants failed, 1 implant had mechanical complications and 6 implants had biological complications. Based on the analysis of implants and patients, the long-term cumulative survival rate of short implants was 94.0%(over 5 years survival rate was 96.4%) and 90.4% respectively. There was no significant difference between the survival rate of short implants and the patient's gender, age, whether to use special operation and the type of jaw teeth(P＜0.05). Smoking and periodontitis were risk factors for failure of short implants(P＜0.05).The difference of short implant survival rate between short implants restoration with combined crowns and single crowns was statistically significant(P＜0.05). The survival rate of short implant in mandible was higher than that in maxilla(P＜0.05). CONCLUSIONS: Under the standards clinical program and operation, short implant can be used to shorten the implant restoration cycle and avoid complicated bone augmentation which can achieve good long-term clinical effect. Short implant should be used to strictly control the risk factors that affect the survival of short implant.

Development of 107 SSR markers from whole genome shotgun sequences of Chinese bayberry (Myrica rubra) and their application in seedling identification.

Chinese bayberry (Myrica rubra Sieb. et Zucc.) is one of the important subtropical fruit crops native to the South of China and Asian countries. In this study, 107 novel simple sequence repeat (SSR) molecular markers, a powerful tool for genetic diversity studies, cultivar identification, and linkage map construction, were developed and characterized from whole genome shotgun sequences. M13 tailing for forward primers was applied as a simple method in different situations. In total, 828 alleles across 45 accessions were detected, with an average of 8 alleles per locus. The number of effective alleles ranged from 1.22 to 10.41 with an average of 4.08. The polymorphic information content (PIC) varied from 0.13 to 0.89, with an average of 0.63. Moreover, these markers could also be amplified in their related species Myrica cerifera (syn. Morella cerifera) and Myrica adenophora. Seventy-eight SSR markers can be used to produce a genetic map of a cross between 'Biqi' and 'Dongkui'. A neighbor-joining (NJ) tree was constructed to assess the genetic relationships among accessions, and the elite accessions 'Y2010-70', 'Y2012-140', and 'Y2012-145', were characterized as potential new genotypes for cultivation.

Determination of the genetic diversity of vegetable soybean [Glycine max (L.) Merr.] using EST-SSR markers.

The development of expressed sequence tag-derived simple sequence repeats (EST-SSRs) provided a useful tool for investigating plant genetic diversity. In the present study, 22 polymorphic EST-SSRs from grain soybean were identified and used to assess the genetic diversity in 48 vegetable soybean accessions. Among the 22 EST-SSR loci, tri-nucleotides were the most abundant repeats, accounting for 50.00% of the total motifs. GAA was the most common motif among tri-nucleotide repeats, with a frequency of 18.18%. Polymorphic analysis identified a total of 71 alleles, with an average of 3.23 per locus. The polymorphism information content (PIC) values ranged from 0.144 to 0.630, with a mean of 0.386. Observed heterozygosity (Ho) values varied from 0.0196 to 1.0000, with an average of 0.6092, while the expected heterozygosity (He) values ranged from 0.1502 to 0.6840, with a mean value of 0.4616. Principal coordinate analysis and phylogenetic tree analysis indicated that the accessions could be assigned to different groups based to a large extent on their geographic distribution, and most accessions from China were clustered into the same groups. These results suggest that Chinese vegetable soybean accessions have a narrow genetic base. The results of this study indicate that EST-SSRs from grain soybean have high transferability to vegetable soybean, and that these new markers would be helpful in taxonomy, molecular breeding, and comparative mapping studies of vegetable soybean in the future.

Plant-soil feedbacks and soil sickness: from mechanisms to application in agriculture.

Negative plant-soil feedbacks play an important role in soil sickness, which is one of the factors limiting the sustainable development of intensive agriculture. Various factors, such as the buildup of pests in the soil, disorder in physico-chemical soil properties, autotoxicity, and other unknown factors may contribute to soil sickness. A range of autotoxins have been identified, and these exhibit their allelopathic potential by influencing cell division, water and ion uptake, dark respiration, ATP synthesis, redox homeostasis, gene expression, and defense responses. Meanwhile, there are great interspecific and intraspecific differences in the uptake and accumulation of autotoxins, which contribute to the specific differences in growth in response to different autotoxins. Importantly, the autotoxins also influence soil microbes and vice versa, leading to an increased or decreased degree of soil sickness. In many cases, autotoxins may enhance soilborne diseases by predisposing the roots to infection by soilborne pathogens through a direct biochemical and physiological effect. Some approaches, such as screening for low autotoxic potential and disease-resistant genotypes, proper rotation and intercropping, proper soil and plant residue management, adoption of resistant plant species as rootstocks, introduction of beneficial microbes, physical removal of phytotoxins, and soil sterilization, are proposed. We discuss the challenges that we are facing and possible approaches to these.

Glutathione biosynthesis and regeneration play an important role in the metabolism of chlorothalonil in tomato.

Glutathione is one of the major endogenous antioxidants produced by cells. In plants, glutathione is crucial for both abiotic and biotic stress resistance, and also involved in the detoxification of xenobiotics in many organisms. However, as in vivo evidences of glutathione function are still lacking so far, its roles in plants are still poorly understood. In this study, we investigated the changes of thiols, glutathione homeostasis and transcripts of genes potentially involved in chlorothalonil (CHT) metabolism in tomato (Solanum lycopersicum L.). Two genes (GSH1, GSH2) encoding γ-glutamylcysteine synthetase and glutathione synthetase, respectively, and a gene for glutathione reductase (GR1) involved in glutathione regeneration were silenced by virus induced gene silencing (VIGS) approach. Silencing of GSH1, GSH2 and GR1 decreased glutathione contents and the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), but increased CHT residues in plant tissues. The GSH1 and GR1 silenced plants showed the lowest GSH level and ratio of GSH/GSSG, respectively. Transcripts of P450, GST and ABC transporter genes as well as glutathione S-transferase (GST) activity were induced after CHT treatment. However, the increases of these transcripts were compromised in GSH1, GSH2 and GR1 silenced plants. This study indicates that glutathione not only serves as a substrate for CHT conjugation, but is also involved in regulation of transcripts of gene in pesticide metabolism via controlling redox homeostasis.

Brassinosteroids accelerate recovery of photosynthetic apparatus from cold stress by balancing the electron partitioning, carboxylation and redox homeostasis in cucumber.

The aim of this study was to examine the role of brassinosteroids (BRs) in protecting the photosynthetic apparatus from cold-induced damage in cucumber (Cucumis sativus) plants. Recovery at both high light (HL) and low light (LL) after a cooling at 10/7°C induced irreversible inhibition of CO2 assimilation, photoinhibition at photosystem I (PSI) and inhibition of enzyme activities of Calvin cycle and ascorbate (AsA)-reduced glutathione (GSH) cycle, followed by accumulation of H2 O2 and malondialdehyde. However, cold-induced photoinhibition at PSII was fully recovered at LL but not at HL. Meanwhile, recovery at HL increased electron flux to O2 -dependent alternative pathway [Ja(O2 -dependent)]. Foliar application of 24-epibrassinolide (EBR) accelerated recovery from photoinhibition of PSII but not of PSI. EBR also significantly increased CO2 assimilation, activity of Calvin cycle enzymes and electron flux to carbon reduction [Je(PCR)], with a concomitant decrease in Ja(O2 -dependent); meanwhile EBR increased the activity of enzymes in AsA-GSH cycle and cellular redox states. However, the positive effect of EBR on plant recovery was observed only at HL, but not LL. These results indicate that BR accelerates the recovery of photosynthetic apparatus at HL by activation of enzymes in Calvin cycle and increasing the antioxidant capacity, which in turn mitigate the photooxidative stress and the inhibition of plant growth during the recovery.

Hydrogen peroxide functions as a secondary messenger for brassinosteroids-induced CO2 assimilation and carbohydrate metabolism in Cucumis sativus.

Brassinosteroids (BRs) are potent regulators of photosynthesis and crop yield in agricultural crops; however, the mechanism by which BRs increase photosynthesis is not fully understood. Here, we show that foliar application of 24-epibrassinolide (EBR) resulted in increases in CO(2) assimilation, hydrogen peroxide (H(2)O(2)) accumulation, and leaf area in cucumber. H(2)O(2) treatment induced increases in CO(2) assimilation whilst inhibition of the H(2)O(2) accumulation by its generation inhibitor or scavenger completely abolished EBR-induced CO(2) assimilation. Increases of light harvesting due to larger leaf areas in EBR- and H(2)O(2)-treated plants were accompanied by increases in the photochemical efficiency of photosystem II (Φ(PSII)) and photochemical quenching coefficient (q(P)). EBR and H(2)O(2) both activated carboxylation efficiency of ribulose-1,5-bisphosphate oxygenase/carboxylase (Rubisco) from analysis of CO(2) response curve and in vitro measurement of Rubisco activities. Moreover, EBR and H(2)O(2) increased contents of total soluble sugar, sucrose, hexose, and starch, followed by enhanced activities of sugar metabolism such as sucrose phosphate synthase, sucrose synthase, and invertase. Interestingly, expression of transcripts of enzymes involved in starch and sugar utilization were inhibited by EBR and H(2)O(2). However, the effects of EBR on carbohydrate metabolisms were reversed by the H(2)O(2) generation inhibitor diphenyleneodonium (DPI) or scavenger dimethylthiourea (DMTU) pretreatment. All of these results indicate that H(2)O(2) functions as a secondary messenger for EBR-induced CO(2) assimilation and carbohydrate metabolism in cucumber plants. Our study confirms that H(2)O(2) mediates the regulation of photosynthesis by BRs and suggests that EBR and H(2)O(2) regulate Calvin cycle and sugar metabolism via redox signaling and thus increase the photosynthetic potential and yield of crops.

Brassinosteroid-induced CO(2) assimilation is associated with increased stability of redox-sensitive photosynthetic enzymes in the chloroplasts in cucumber plants.

Brassinosteroids (BRs) play important roles in plant growth, development, photosynthesis and stress tolerance; however, the mechanism underlying BR-enhanced photosynthesis is currently unclear. Here, we provide evidence that an increase in the BR level increased the quantum yield of PSII, activities of Rubisco activase (RCA) and fructose-1,6-bisphosphatase (FBPase), and CO(2) assimilation. BRs upregulated the transcript levels of genes and activity of enzymes involved in the ascorbate-glutathione cycle in the chloroplasts, leading to an increased ratio of reduced (GSH) to oxidized (GSSG) glutathione in the chloroplasts. An increased GSH/GSSG ratio protected RCA from proteolytic digestion and increased the stability of redox-sensitive enzymes in the chloroplasts. These results strongly suggest that BRs are capable of regulating the glutathione redox state in the chloroplasts through the activation of the ascorbate-glutathione cycle. The resulting increase in the chloroplast thiol reduction state promotes CO(2) assimilation, at least in part, by enhancing the stability and activity of redox-sensitive photosynthetic enzymes through post-translational modifications.

Development and characterization of 41 novel EST-SSR markers for Pisum sativum (Leguminosae).

PREMISE OF THE STUDY: Expressed sequence tag (EST)-derived simple sequence repeat (SSR) markers were developed in Pisum sativum for further use in genetic studies and breeding programs. METHODS AND RESULTS: Forty-one novel EST-SSR primers were developed and characterized for size polymorphism in 32 Pisum sativum individuals from four populations from China. In each population, the number of alleles per locus ranged from one to seven, with observed heterozygosity and expected heterozygosity ranging from 0 to 0.8889 and 0 to 0.8400, respectively. Furthermore, 53.7% of these markers could be transferred to the related species, Vicia faba. CONCLUSIONS: The developed markers have potential for application in the study of genetic diversity, germplasm appraisal, and marker-assisted breeding in pea and other legume species.

Cellular glutathione redox homeostasis plays an important role in the brassinosteroid-induced increase in CO2 assimilation in Cucumis sativus.

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(2)O(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(2)O(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(2)O(2) scavenger or inhibition of H(2)O(2) generation, GSH biosynthesis and the NADPH-generating pentose phosphate pathway. BR-, H(2)O(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(2)O(2) -mediated increase in the GSH:GSSG ratio, which may positively regulate the synthesis and activation of redox-sensitive enzymes in carbon fixation.

The growth, photosynthesis and antioxidant defense responses of five vegetable crops to phenanthrene stress.

Polycyclic aromatic hydrocarbons (PAHs) are global environmental problem. To better understand the growth and physiological responses to atmospheric PAHs, we investigated biomass, photosynthetic machinery and antioxidant system in pakchoi, cucumber, flowering chinese cabbage, tomato and lettuce under various levels of phenanthrene (PHE) stress. Foliar exposure to PHE for 14d resulted in a dose dependent decrease in growth, photosynthesis and chlorophyll contents. With few exceptions, antioxidant enzymes (superoxide dismutase, guaicol peroxidase, catalase, ascorbate peroxidase and glutathione reductase) were upregulated following exposure to PHE. Dose dependent increase in malondialdehyde contents together with H(2)O(2) accumulation suggested an occurrence of oxidative stress following PHE exposure. However, to some extent, growth and antioxidant defense responses differ from species to species. Difference in defense capacity might result in different tolerance and phytotoxicity among the studied vegetables. Taken together, phytotoxicity of PHE to five vegetables could be sequenced in the following order: pakchoi>cucumber>lettuce>tomato>flowering chinese cabbage.

Brassinosteroids induce plant tolerance against phenanthrene by enhancing degradation and detoxification in Solanum lycopersicum L.

Polycyclic aromatic hydrocarbons (PAHs) are toxic to both plants and animals. The enhancement of plant tolerance and detoxification capacity is important for the plant-based remediation of PAHs. Therefore, we investigated the effects of 24-epibrassinolide (EBR) on the metabolism of a three-ringed PAH (phenanthrene-PHE) and subsequent stress tolerance in tomato (Solanum lycopersicum L.) plants. Exposure to PHE (300 µM) for 21 d significantly decreased biomass and net CO(2) assimilation (P(n)) but induced photoinhibition, malondialdehyde (MDA), H(2)O(2) and antioxidant enzymes. Obvious ultrastructural alterations were observed in the PHE-treated root tip cells. Importantly, the foliar application of EBR (0.1 µM) significantly increased biomass, P(n) and antioxidant enzyme activities but decreased MDA and H(2)O(2) compared with PHE alone and saved the root cells from severe damage. The expression of detoxification genes (CYP90b3, GSH1, GST1), reduced glutathione (GSH) content and glutathione S-transferase activity in the EBR+PHE-treated plants were higher than those of PHE alone. Additionally, lower levels of PHE residues in the roots were observed as a result of EBR+PHE treatment. Taken together, our results strongly suggest an enhanced and coordinated detoxification and degradation of PHE by EBR.

Brassinosteroid alleviates phenanthrene and pyrene phytotoxicity by increasing detoxification activity and photosynthesis in tomato.

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.

Developing new SSR markers from ESTs of pea (Pisum sativum L.).

The development of expressed sequence tags (ESTs) from pea has provided a useful source for mining novel simple sequence repeat (SSR) markers. In the present research, in order to find EST-derived SSR markers, 18 552 pea ESTs from the National Center for Biotechnology Information (NCBI) database were downloaded and assembled into 10 086 unigenes. A total of 586 microsatellites in 530 unigenes were identified, indicating that merely 5.25% of sequences contained SSRs. The most abundant SSRs within pea were tri-nucleotide repeat motifs, and among all the tri-nucleotide repeats, the motif GAA was the most abundant type. In total, 49 SSRs were used for primer design. EST-SSR loci were subsequently screened on 10 widely adapted varieties in China. Of these, nine loci showed polymorphic profiles that revealed two to three alleles per locus. The polymorphism information content value ranged from 0.18 to 0.58 with an average of 0.41. Furthermore, transferable analysis revealed that some of these loci showed transferability to faba bean. Because of their polymorphism and transferability, these nine novel EST-SSRs will be valuable tools for marker-assisted breeding and comparative mapping of pea in the future.

Generation and characterization of 11 novel est derived microsatellites from Vicia faba (Fabaceae).

PREMISE OF THE STUDY: Simple sequence repeat (SSR) markers were developed for faba bean using expressed sequence tags (ESTs) from the NCBI database to study for genetic diversity. • METHODS AND RESULTS: A total of 11 novel EST-SSR loci were generated and characterized when tested on four populations of 29 faba bean individuals from China and Europe. The number of alleles (A) ranged from 1 to 3 in each population, and observed heterozygosity (H(O)) and expected heterozygosity (H(E)) ranged from 0 to 0.5000 and 0.6400, respectively. Furthermore, transferable analysis revealed that eight of these loci (72.73%) amplified in Pisum sativum L., six of which (75.00%) detected polymorphism. • CONCLUSIONS: The developed markers in this study will provide valuable tools for genetic diversity, resource conservation, genetic mapping, and marker-assisted breeding of faba bean in the future.

Brassinosteroids promote photosynthesis and growth by enhancing activation of Rubisco and expression of photosynthetic genes in Cucumis sativus.

Brassinosteroids (BRs) are a new group of plant growth substances that promote plant growth and productivity. We showed in this study that improved growth of cucumber (Cucumis sativus) plants after treatment with 24-epibrassinolide (EBR), an active BR, was associated with increased CO(2) assimilation and quantum yield of PSII (Phi(PSII)). Treatment of brassinazole (Brz), a specific inhibitor for BR biosynthesis, reduced plant growth and at the same time decreased CO(2) assimilation and Phi(PSII). Thus, the growth-promoting activity of BRs can be, at least partly, attributed to enhanced plant photosynthesis. To understand how BRs enhance photosynthesis, we have analyzed the effects of EBR and Brz on a number of photosynthetic parameters and their affecting factors, including the contents and activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Northern and Western blotting demonstrated that EBR upregulated, while Brz downregulated, the expressions of rbcL, rbcS and other photosynthetic genes. In addition, EBR had a positive effect on the activation of Rubisco based on increased maximum Rubisco carboxylation rates (V (c,max)), total Rubisco activity and, to a greater extent, initial Rubisco activity. The accumulation patterns of Rubisco activase (RCA) based on immunogold-labeling experiments suggested a role of RCA in BR-regulated activation state of Rubisco. Enhanced expression of genes encoding other Calvin cycle genes after EBR treatment may also play a positive role in RuBP regeneration (J (max)), thereby increasing maximum carboxylation rate of Rubisco (V (c,max)). Thus, BRs promote photosynthesis and growth by positively regulating synthesis and activation of a variety of photosynthetic enzymes including Rubisco in cucumber.

Reactive oxygen species are involved in brassinosteroid-induced stress tolerance in cucumber.

Brassinosteroids (BRs) induce plant tolerance to a wide spectrum of stresses. To study how BR induces stress tolerance, we manipulated the BR levels in cucumber (Cucumis sativus) through a chemical genetics approach and found that BR levels were positively correlated with the tolerance to photo-oxidative and cold stresses and resistance to Cucumber mosaic virus. We also showed that BR treatment enhanced NADPH oxidase activity and elevated H(2)O(2) levels in apoplast. H(2)O(2) levels were elevated as early as 3 h and returned to basal levels 3 d after BR treatment. BR-induced H(2)O(2) accumulation was accompanied by increased tolerance to oxidative stress. Inhibition of NADPH oxidase and chemical scavenging of H(2)O(2) reduced BR-induced oxidative and cold tolerance and defense gene expression. BR treatment induced expression of both regulatory genes, such as RBOH, MAPK1, and MAPK3, and genes involved in defense and antioxidant responses. These results strongly suggest that elevated H(2)O(2) levels resulting from enhanced NADPH oxidase activity are involved in the BR-induced stress tolerance.

Effects of cucumber mosaic virus infection on electron transport and antioxidant system in chloroplasts and mitochondria of cucumber and tomato leaves.

We examined the responses of the photosynthetic and respiratory electron transport and antioxidant systems in cell organelles of cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) leaves to infection of cucumber mosaic virus (CMV) by comparing the gas exchange, Chl fluorescence, respiratory electron transport, superoxide dismutase (SOD, EC 1.15.1.1) and ascorbate-glutathione (AsA-GSH) cycle enzymes and the production of H(2)O(2) in chloroplasts, mitochondria and soluble fraction in virus-infected and non-infected leaves. Long-term CMV infection resulted in decreased photosynthesis and respiration rates. Photosynthetic electron flux to carbon reduction, respiratory electron transport via both complex I and complex II and also the Cyt respiration rate all significantly decreased, while photosynthetic alternative electron flux and alternative respiration significantly increased. These changes in electron transport were accompanied by a general increase in the activities of SOD/AsA-GSH cycle enzymes followed by an increased H(2)O(2) accumulation in chloroplasts and mitochondria. These results demonstrated that disturbance of photosynthetic and respiratory electron transport by CMV also affected the antioxidative systems, thereby leading to oxidative stress in various organelles.