Heterogeneous expression of stearoyl-acyl carrier protein desaturase genes SAD1 and SAD2 from Linum usitatissimum enhances seed oleic acid accumulation and seedling cold and drought tolerance in Brassica napus

Flax(Linum usitatissimum L.)is a versatile crop and its seeds are a major source of unsaturated fatty acids.Stearoyl-acyl carrier protein desaturase(SAD)is a dehydrogenase enzyme that plays a key role in oleic acid biosynthesis as well as responses to biotic and abiotic stresses.However,the function of SAD orthologs from L.usitatissimum has not been assessed.Here,we found that two LuSAD genes,LuSAD1 and LuSAD2,are present in the genome of L.usitatissimum cultivar‘Longya 10’.Heterogeneous expression of either LuSAD1 or LuSAD2 in Arabidopsis thaliana resulted in higher contents of total fatty acids and oleic acid in the seeds.Interestingly,ectopic expression of LuSAD2 in A.thaliana caused altered plant architecture.Similarly,the overexpression of either LuSAD1 or LuSAD2 in Brassica napus also resulted in increased contents of total fatty acids and oleic acid in the seeds.Furthermore,we demonstrated that either LuSAD1 or LuSAD2 enhances seedling resistance to cold and drought stresses by improving antioxidant enzyme activity and nonenzymatic antioxidant levels,as well as reducing membrane damage.These findings not only broaden our knowledge of the LuSAD functions in plants,but also offer promising targets for improving the quantity and quality of oil,and the abiotic stress tolerance of oil-producing crops,through molecular manipulation.

Protective effects of oleic acid and polyphenols in extra virgin olive oil on cardiovascular diseases

The Mediterranean diet has long been recognized as one of the most effective ways to prevent and improve cardiovascular disease.Extra virgin olive oil(EVOO)is the typical sources of fat in the Mediterranean diet which have been shown to have noteworthy nutritional value and positive impact on human health.It is worth noting that EVOO owes its superior nutritional value to its bioactive composition.The main component of EVOO is monounsaturated fatty acids(MUFAs)in the form of oleic acid.Oleic acid accounts for up to 70%-80%of EVOO.Secondly,EVOO contains approximately more than 30 phenolic compounds,of which HT is essential for the protection against cardiovascular diseases.In this review,we focused on the potential mechanisms of oleic acid and polyphenols combat cardiovascular diseases risk in terms of oxidative stress,inflammation,blood pressure,endothelial function and cholesterol.This review might provide a reference for the studies on cardiovascular protective effects of EVOO.

Pyramiding of multiple genes generates rapeseed introgression lines with clubroot and herbicide resistance, high oleic acid content, and early maturity

Clubroot and herbicide resistance,high oleic acid(OA)content,and early maturity are targets of rapeseed(Brassica napus L.)breeding.The objective of this study was to develop new male-fertility restorer lines by pyramiding favorable genes to improve these traits simultaneously.Seven elite alleles for the four traits were introduced into the restorer line 621R by speed breeding with marker-assisted and phenotypic selection.Six introgression lines(ILs)were developed with four-to seven-gene combinations and crossed with two elite parents to develop hybrids.All ILs and their corresponding hybrids displayed high resistance to both clubroot pathotype 4 and sulfonylurea herbicides.Three ILs and their hybrids showed large increases in OA contents and four showed earlier maturity.These new ILs may be useful in rapeseed hybrid breeding for the target traits.

The protective effect of oleic acid on Lactiplantibacillus plantarum during freeze-drying

Membrane characteristics are determined by the fatty acids composition,which affects survival rates after freeze-drying.However,it is unknown which composition provides the greatest effect.In this study,we found that the addition of Tween 80 and Tween 20 significantly increased survival rates of Lactiplantibacillus plantarum,which reached a maximum of 93.1%.Conversely,Tween 60 caused a significant decrease.We further found that the difference between the effects of adding Tween 80 and Tween 60 was the change in oleic acid contents.To verify the role of oleic acid,we used CRISPR-Cas9 to knock-out the key synthesis gene cla-er.The survival rates of L.plantarum AR113Δcla-er declined to 5.48%.The addition of oleic acid restored the rates to those of wild type strains.Moreover,the membrane integrity and fl uidity of knockout strains markedly decreased.This is the fi rst confi rmation that Tween 80 or Tween 20 increases the survival rate by increasing the content of oleic acid in the cell membrane.These fi ndings also indicated that oleic acid in cell membranes has a substantial protective effect on L.plantarum during freeze-drying.

Bioinformatics and Functional Analysis of High Oleic Acid-Related Gene GmSAM22 in Soybean [Glycine max (L.) Merr.]

High yield,high quality,stable yield,adaptability to growth period,and modern mechanization are the basic requirements for crops in the 21st century.Soybean oleic acid is a natural unsaturated fatty acid with strong antioxidant properties and stability.Known as a safe fatty acid,it has the ability to successfully prevent cardiovascular and cerebrovascular disorders.Improving the fatty acid composition of soybean seeds,can not only speed up the breeding process of high-quality high-oil and high-oleic soybeans,but also have important significance in human health,and provide the possibility for the development of soybean oil as a new energy source.Hence,the aim of this study was to analyze the high oleic acid elated gene GmSAM22 in soybean.In this research the soybean oleic acid-related gene GmSAM22 was screened out by Genome-wide association analysis,a 662 bp fragment was acquired by specific PCR amplification,and the pMD18T cloning vector was linked by the use of a seamless cloning technique.Bioinformatics analysis of the signal peptide prediction,subcellular localization,protein hydrophobicity,transmembrane region analysis,a phosphorylation site,protein secondary and tertiary structure and protein interaction analysis of the protein encoded by the SAM22 gene was carried out.The plasmid of the gene editing vector is pBK041.The overexpression vector was transformed from pCAMBIA3301 as the base vector,and overexpression vector were designed.Positive plants were obtained by genetic transformation by the pollen tube channel method.Fluorescence quantitative PCR was performed on the T2 generation plants to detect the relative expression levels in different tissues.Southern Blot was used to detect the presence of hybridization signal.Screening genes BAR,35S,and NOS in plants were identified by conventional PCR.10 seeds with high and low oleic acid content were chosen for quantitative PCR identification,and finally,the concentration and morphology of soybean fatty acids were identified by nearfar infrared spectroscopy.On 10 seeds with an upper and lower oleic acid content,a quantitative fluorescence analysis was done.In Southern blot hybridization,the SAM22 gene was integrated into the recipient soybean plant in hands of a sole copy.Fluorescence quantitative PCR appeared that the average relative expression of the SAM22 gene in roots,stems,leaves,and seeds was 1.70,1.67,3.83,and 4.41,respectively.Positive expression seeds had a 4.77%increase in oleic acid content.The level of oleic acid in the altered seeds was reduced by 4.13%when compared to CK,and it was discovered that the GmSAM22 gene could be a regulatory and secondary gene that promotes the conversion of stearic acid to oleic acid in soybean.There has not been a discussion of gene cloning or functional verification.The cloning and genetic transformation of the soybean SAM22 gene can effectively increase the content of oleic acid,which lays a foundation for the study of soybean with high oleic acid.

Comparison of the Δ^(12) fatty acid desaturase gene between high-oleic and normal-oleic peanut genotypes

△^12 fatty acid desaturase gene has been targeted as a logical candidate controlling the high oleate trait in peanut seeds. By RT-PCR method, the full-length cDNAs of △^12 fatty acid desaturase gene were isolated from peanut （Arachis hypogaea L.） genotypes with normal and high ratio of oleic to linoleic acid, which were designated AhFAD2B and AhFAD2B＇, respectively. Sequence alignment of their coding regions revealed that an extra A was inserted at the position ＋442 bp of AhFAD2B＇ sequence of high oleic acid genotypes, which resulted in the shift of open reading frame and a truncated protein AhFAD2B＇, with the loss of one histidine box involved in metal ion complex required for the reduction of oxygen. Analysis of transcript level showed that the expression of △^12 fatty acid desaturase gene in high oleic acid genotype was slightly lower than that in normal genotype. The enzyme activity experiment of yeast （Saccharomyces cerevisiae） cell transformed with AhFAD2B or AhFAD2B＇ proved that only AhFAD2B gene product showed significant △^12 fatty acid desaturase activity, but AhFAD2B＇ gene product did not. These results suggested that the change of AhFAD2B＇ gene sequence resulted in lower activity or deactivation of △^12 fatty acid desaturase in high oleic acid genotype.

Synergistic mechanism between SDBS and oleic acid in anionic flotation of rhodochrosite

Pure mineral flotation experiments, zeta potential testing, and infrared spectroscopy were employed to investigate the interracial reactions of oleic acid （collector）, sodium dodecyl benzene sulfonate （SDBS, synergist）, and rhodochrosite in an anionic system. The pure mineral test shows that oleic acid has a strong ability to collect products on rhodochrosite. Under neutral to moderately alkaline conditions, low temperature （e.g., 10℃） adversely affects the flotation performance of oleic acid; the addition of SDBS significantly improves the dis- persion and solubility of oleic acid, enhancing its collecting ability and flotation recovery. The zeta potential test shows that rhodochrosite interacts with oleic acid and SDBS, resulting in a more negative zeta potential and the co-adsorption of the collector and synergist at the mineral surface. Infrared spectroscopy demonstrated that when oleic acid and SDBS are used as a mixed collector, oleates along with -COO- and --COOH functional groups are formed on the mineral surface, indicating chemical adsorption on rhodochrosite. The results demonstrate that oleic acid and SDBS co-adsorb chemically on the surface ofrhodochrosite, thereby improving the flotation performance of the collector.

Oleic Acid (OA), A Potential Dual Contrast Agent for Postmortem MR Angiography (PMMRA): A Pilot Study

Summary:Choosing proper perfusates as contrast agents is an important aspect for postmortem magnetic resonance angiography(PMMRA).However,in this emerging field,the number of suitable kinds of liquid is still very limited.The objective of this research is to compare MR images of oleic acid(OA)with paraffin oil(PO)in vitro and in ex situ animal hearts,in order to evaluate the feasibility to use OA as a novel contrast agent for PMMRA.In vitro,OA,PO and water(control)were introduced into three tubes separately and T,weighted-spin echo(Tw SE)and T2w-SE images were acquired on a 1.5T MR scanner.In the second experiment,0A and PO were injected into left coronary artery(LCA)and left ventricle(LV)of ex situ bovine hearts and their Tw-SE,Tzw-SE,Tw-multipoint Dixon(Tjw-mDixon)and 3DT2w-mDixon images were acquired.The overall results indicate that OA may have a potential to be used as a dual(T and T2 based)contrast agent for PMMRA when proper sequence parameters are utilized.However,as the pilot study was based on limited number of animal hearts,more researches using OA in cadavers are needed to validate our findings.

Oleic acid reduces steroidogenesis by changing the lipid type stored in lipid droplets of ovarian granulosa cells

Background:Oleic acid is an abundant free fatty acid present in livestock that are in a negative energy-balance state,and it may have detrimental effects on female reproduction and fertility.Oleic acid induces lipid accumulation in bovine granulosa cells,which leads to a foam cell-like morphology and reduced steroidogenesis.However,why oleic acid increases lipid accumulation but decreases steroidogenesis remains unclear.This study focused on oleic acid’s effects on lipid type and steroidogenesis.Results:Oleic acid increased the lipid accumulation in a concentration-dependent manner and mainly increased the triglyceride level and decreased the cholesterol ester level.Oleic acid also led to a decline in estradiol and progesterone production in porcine granulosa cells in vitro.In addition,oleic acid up-regulated the expression of CD36 and diacylglycerol acyltransferase 2,but down-regulated the expression of 3-hydroxy-3-methylglutarylcoenzyme A reductase,scavenger receptor class B member 1 and acetyl-Coenzyme A acetyltransferase 2,as well as steroidogenesis-related genes,including cytochrome P450 family 11 subfamily A member 1,cytochrome P450family 19 subfamily A member 1 and 3 as well as steroidogenic acute regulatory protein at the mRNA and protein levels.An oleic acid-rich diet also enhanced the triglyceride levels and reduced the cholesterol levels in ovarian tissues of female mice,which resulted in lower estradiol levels than in control-fed mice.Compared with the control,decreases in estrus days and the numbers of antral follicles and corpora lutea,as well as an increase in the numbers of the atretic follicles,were found in the oleic acid-fed female mice.Conclusions:Oleic acid changed the lipid type stored in lipid droplets of ovarian granulosa cells,and led to a decrease in steroidogenesis.These results improve our understanding of fertility decline in livestock that are in a negative energy-balance state.

The Influence of Oleic Acid on the Hydration and Mechanical Properties of Portland Cement

To investigate the effects of OA on the portland cement using oleic acid （OA） as grinding aid and the effects of OA on the portland cement, we characterized the different perfermances of the cement, discussed the characteristics of properties. The results reveal that the OA can reduce the water requirement of normal consistency. With the content of OA added, setting time was extended. The OA can significantly improve the rheological properties of cement-based materials, while the compressive strength decreases.

Improvement of three popular Indian groundnut varieties for foliar disease resistance and high oleic acid using SSR markers and SNP array in marker-assisted backcrossing

Foliar fungal diseases(rust and late leaf spot)incur large yield losses,in addition to the deterioration of fodder quality in groundnut worldwide.High oleic acid has emerged as a key market trait in groundnut,as it increases the shelf life of the produce/products in addition to providing health benefits to consumers.Marker-assisted backcrossing(MABC)is the most successful approach to introgressing or pyramiding one or more traits using traitlinked markers.We used MABC to improve three popular Indian cultivars(GJG 9,GG 20,and GJGHPS 1)for foliar disease resistance(FDR)and high oleic acid content.A total of 22 BC3F4 and 30 BC2F4 introgression lines(ILs)for FDR and 46 BC3F4 and 41 BC2F4 ILs for high oleic acid were developed.Recurrent parent genome analysis using the 58 K Axiom_Arachis array identified several lines showing upto 94%of genome recovery among second and third backcross progenies.Phenotyping of these ILs revealed FDR scores comparable to the resistant parent,GPBD 4,and ILs with high(~80%)oleic acid in addition to high genome recovery.These ILs provide further opportunities for pyramiding FDR and high oleic acid in all three genetic backgrounds as well as for conducting multi-location yield trials for further evaluation and release for cultivation in target regions of India.

Inheritance of Erucic Acid,Glucosinolate,and Oleic Acid Contents in Rapeseed (Brassica napus L.)

This study was conducted to verify the inheritance of certain characters of rapeseed including erucic acid, glucosinolate and oleic acid contents by using generation mean analysis. The cross of lines Ⅲ174×Zi20 （F1）, F2, BC1 （F1×P1）, BC2 （F1×P2）, and parents （P1 and P2） were evaluated in the field. Data were measured on individual plants for oleic acid, erucic acid, and glucosinolate contents. Transgressive variations in F2 population were observed for oleic acid content, indicating that dominance and recessive genes distributed in both parents. Scaling test indicated that the effects of genes controlling these characters did not follow the additivedominance model. The data for three characters were analyzed using six parameter models and found that one or more types of epistatic gene effects were important for glucosinolate content. High broad sense heritabilities were obtained for erucic acid, oleic acid, and glucosinolate contents with the values of 98.97%, 93.68%, and 86.17%, respectively. Two major gene pairs were found to control the expression of erucic acid and oleic acid contents, while three major gene pairs were detected to control glucosinolate content.

Oleic acid Stimulates the Formation of Adipocyte-Like Cells from Bovine Satellite Cells via <i>G-Protein Coupled Receptor 43</i>and <i>CCAAT/Enhancer-Binding Protein Beta</i>

Numerous physiological and pathological processes are controlled by free fatty acids, which act as signaling molecules in mammals. We hypothesized that oleic acid (Ole) might stimulate the formation of satellite-cell-derived intramuscular adipose tissue. The role of Ole as a ligand of G-protein-coupled receptor 43 (GPR43) was previously identified. Thus, the objective of the current study was to determine the effect of Ole on GPR43 and factors related to the adipogenic differentiation of bovine satellite cells (BSC). Treatments of 100 μM and 500 μM Ole tended to induce greater (P < 0.10) mRNA expression of CCAAT/enhancer-binding protein β (C/EBPβ) compared to all other doses. The mRNA abundance of peroxisome proliferator-activated receptor γ (PPARγ) was not altered (P > 0.10) by treatment. The addition of 100 μM and 500 μM of Ole upregulated (P < 0.05) GPR43 mRNA expression. Protein level of GPR43 was increased (P < 0.05) by 100 μM of Ole treatments. Addition of Ole to BSC cultures induced transformation of myogenic cells into adipocyte-like cells that formed cytoplasmic lipid droplets. Increased expression of C/EBPβ in response to Ole might suppress myogenic differentiation. After the treatment of cells with Ole, increased expression of GPR43 could lead to phosphorylation of 5’ AMP-activated protein kinase α (AMPKα). Altogether, the results indicated that increased Ole might stimulate adipose tissue accumulation within the skeletal muscle of cattle by promoting adipogenic differentiation and activation of GPR43 in satellite cells.

Preparation and UV-light Absorption Property of Oleic Acid Surface Modified ZnO Nanoparticles

Syntheses of zince oxide（ZnO） nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry（XRD）, transmission electron microscopy（TEM）, infrared spectroscopy（IR） and UV-Vis spectroscopy. The prepared ZnO nanoparticles were nearly spherical and highly crystalline with an average size of 29 nm. In addition, high UV-light absorption properties of oleic acid surface modified ZnO nanoparticles were successfully obtained for a dispersion of ZnO nanoparticles in ethanol.

Esterification of Glycerol by Oleic Acid and Selective Hydrogenation of Oieic Acid Methylester Over Acid and Ru-Sn-B Supported Mesoporous AIMCM-41

The AlMCM-41 molecular sieves with two different pore sizes are hydrothermally synthesized in the presence of surfactants with two different chain lengths. H-AlMCM-41 and Ru-Sn-B/H-AlMCM-41 which are prepared by the conventional ion-exchange and incipient wetness techniques of the AlMCM-41 show fair catalytic activity for esterification of glycerol by oleic acid and selective hydrogenation of oleic acid methylester, respectively.

Variation and Correlation of Erucic Acid,Oleic Acid and Glucosinolate Contents in Brassica rapa Seeds

In order to screen and identify excellent breeding resources and provide basic materials for Brassica rapa breeding,the contents of erucic acid,oleic acid and glucosinolate in 84 kinds of B. rapa were determined by near-infrared spectroscopy,and the correlations among them were also analyzed. The results showed that the content of erucic acid and oleic acid were significantly negatively correlated,the contents of erucic acid and glucosinolate were significantly positively correlated,while the contents of oleic acid and glucosinolate were significantly negatively correlated; principal component analysis( PCA) were performed on the population materials,factors 1 and 2 were extracted for plotting,factor 1 and factor 2 could explain 73. 7% and 23. 2% of the phenotypic variation,respectively; through cluster analysis,79 materials aggregated to form group I,and five special variants deviated from the population. The variation of erucic acid,oleic acid and glucosinolates in B. rapa populations was rich and there was significant correlation. Through cluster analysis,five excellent B. rapa breeding materials( No. 32,No. 45,No. 46,No. 50,and No. 59) were screened.

Kinetics of Reaction of Bromo-epoxy Resin with Oleic Acid catalyzed by Dimethyl benzyl amine

The kinetics of reaction of bromo-epoxy resin with oleic acid in the presence of dimethylbenzylamine catalyst was studied. The reaction is a zero order reaction with respect to oleic acid, first order with respect to epoxy group and 0. 74 order with respect to dimethylbenzylamine. The reaction rate constants at various temperatures and activation energy were determined. The mechanism of this reaction was discussed. Keywords Tetrabromobisphenol-A, Bromo-epoxy resin, Oleic acid kinetics, Reaction mechanism

BnGLO4 gene cloning and bioinformatics analysis in Brassica napus L

High oleic acid rapeseed oil offers superior nutritional and health benefits,but its mass production is limited due to poor resistance and slightly lower yield.Photosynthesis serves as the foundation of biological survival and closely correlates with crop resistance to stresses,yield,and quality.To identify photosynthesis-related genes,transcriptome sequencing was conducted on high oleic acid rapeseed Gaoyousuan No.1 and low oleic acid rapeseed Xiangyou 15 resulting in the identification of a total of 9396 differentially expressed genes(4669 upregulated and 4727 down-regulated).From these genes nine candidate genes were screened using GO and KEGG analysis with BnGLO4 being selected for cloning purposes.The BnGLO4 gene fragment has a length of 1161 bp with an ORF sequence of 1092 bp encoding a theoretical isoelectric point of pI 7.60;it encodes an unstable lipid-soluble protein localized in peroxisomes without transmembrane structural domains or signal peptides.Its amino acid sequence homology was highest with that of BnaA01G0355200ZS,BnaA01G0355600ZS,BnaA05G0410400ZS,BnaC01G0441800ZS,and Brassica rapa(XP_009117145.1),Brassica napus(CDY39100.1),Brassica cretica(KAF3533604.1)and Brassica oleracea var.oleracea(XP_013610644.1)belonging to the same cruciferous family.The BnGLO4 gene may be associated with responses to abiotic stresses such as salt,drought,and temperature extremes along with photosynthesis and growth in rapeseed plants.The expression levels of the GLO4 gene(BnaA01G0355200 ZS)were highest in filaments while being higher at each stage in seeds and siliques with the highest expression level at day 14 in seeds.Expression was significantly upregulated after 3 h of salt stress treatment,reaching a maximum at 12 h before slightly decreasing at 24 h.The findings of this study lay a foundation for further investigation on photosynthesis and stress response in high oleic rapeseed.

Palm oil protectsα-linolenic acid from rumen biohydrogenation and muscle oxidation in cashmere goat kids

Background:In ruminants,dietary C18:3n-3 can be lost through biohydrogenation in the rumen;and C18:3n-3 that by-passes the rumen still can be lost through oxidation in muscle,theoretically reducing the deposition of C18:3n-3,the substrate for synthesis of poly-unsaturated fatty acids(n-3 LCPUFA)in muscle.In vitro studies have shown that rumen hydrogenation of C18:3n-3 is reduced by supplementation with palm oil(rich in cis-9 C18:1).In addition,in hepatocytes,studies with neonatal rats have shown that cis-9 C18:1 inhibits the oxidation of C18:3n-3.It therefore seems likely that palm oil could reduce both rumen biohydrogenation of C18:3n-3 and muscle oxidation of C18:3n-3.The present experiment tested whether the addition of palm oil to a linseed oil supplement for goat kids would prevent the losses of C18:3n-3 and thus improve the FA composition in two muscles,Longissimus dorsi and Biceps femoris.To investigate the processes involved,we studied the rumen bacterial communities and measured the mRNA expression of genes related to lipid metabolism in Longissimus dorsi.Sixty 4-month-old castrated male Albas white cashmere kids were randomly allocated among three dietary treatments.All three diets contained the same ingredients in the same proportions,but differed in their fat additives:palm oil(PMO),linseed oil(LSO)or mixed oil(MIX;2 parts linseed oil plus 1 part palm oil on a weight basis).Results:Compared with the LSO diet,the MIX diet decreased the relative abuandance of Pseudobutyrivibrio,a bacterial species that is positively related to the proportional loss rate of dietary C18:3n-3 and that has been reported to generate the ATP required for biohydrogenation(reflecting a decrease in the abundance of rumen bacteria that hydrogenate C18:3n-3 in MIX kids).In muscle,the MIX diet increased concentrations of C18:3n-3,C20:5n-3,C22:6n-3,and n-3 LCPUFA,and thus decreased the n-6/n-3 ratio;decreased the mRNA expression of CPT1β(a gene associated with fatty acid oxidation)and increased the mRNA expression of FADS1 and FADS2(genes associated with n-3 LCPUFA synthesis),compared with the LSO diet.Interestingly,compared to Longissimus dorsi,Biceps femoris had greater concentrations of PUFA,greater ratios of unsaturated fatty acids/saturated fatty acids(U/S),and poly-unsaturated fatty acids/saturated fatty acids(P/S),but a lesser concentration of saturated fatty acids(SFA).Conclusions:In cashmere goat kids,a combination of linseed and palm oils in the diet increases the muscle concentration of n-3 LCPUFA,apparently by decreasing the relative abundance of rumen bacteria that are positively related to the proportional loss rate of dietary C18:3n-3,by inhibiting mRNA expression of genes related to C18:3n-3 oxidation in muscle,and by up-regulating mRNA expression of genes related to n-3 LCPUFA synthesis in muscle,especially in Longissimus dorsi.

CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLYPROPYLENE FILLED WITH SiO_2 NANOPARTICLES

Oleic acid （OA）-modified SiO2 （OA-m-SiO2） nanoparticles were prepared using surface modification method. Infrared spectroscopy （IR） was used to investigate the structure of the OA-m-SiO2 nanoparticles, and the result showed that OA attached onto the surface of SiO2 nanoparticles through esterification. Effect of OA concentration on the dispersion stability of OA-m-SiO2 in heptane was also studied, and the result indicated that OA-m-SiO2 nanoparticles were dispersed in heptane more stably than the unmodified ones. OA-m-SiO2 nanoparticles can also be dispersed in polypropylene （PP） matrix in nano-scale. The effect of OA-m-SiO2 on crystallization of PP was studied by means of DSC. It was found that the introduction of OA-m-SiO2 resulted in significant increase in the crystallization temperature, crystallization degree and crystallization rate of PP, and OA-m-SiO2 could effectively induce the formation of β-crystal PP. Effect of OA-m-SiO2 content on mechanical properties of PP/OA-m-SiO2 nanocomposites was also studied. The results show that OA-m-SiO2 can significantly improve the mechanical properties of PP.