A pair of specific primers was designed and used for detection of Xanthomonas oryzae pv.oryzicola(Xooc),the rice bacterial leaf streak pathogen.The results showed:all tested Xooc strains(31 isolates) were specific detected,15 strains of Xanthomonas oryzae pv.oryzae and other tested bacteria strains had not any amplification signal.The detection limit was 20 cells.Xooc was successfully detected from the seeds harvest from the natural infected and artificially inoculated rice plants.

Pathogenic type of Curvularia lunata from Heilongjiang,Jilin,Liaoning and Hebei provinces was analyzed.Twenty-six isolates of C.lunata were divided into four groups by differential hosts.High and moderate pathogenic types were distributed in Wafangdiang city in Liaoning province,Gongzhuling city in Jilin province and Baodin city in Hebei province.A significant diversity of C.lunata was found according to the difference of isozymes including esterase,peroxidase,polyphenol oxidase,superoxide dimutase and malate dehydrogenase.The obvious difference in numbers of bands of isozymes were dectcted.

Dichondra brown leaf spot is a new disease in the China.The percentage of the diseased leaves reached 90% in 2005 in Yaan city,Sichuan province,China,which caused decline and death of the grass.The symptom of the disease was described.Pyrenophora dichondrae sp.nov.was described based on morphologied character of asci and ascospores from the dichondra brown leaf spot.The new a species was cha-racterized by pseudothecia,asci and ascospores with sizes(278-374)μm×(105-144)μm,(152-189)μm×(43-54)μm and(36-52)μm×(10-23)μm and numbers of diaphragm 4-5 of horizontal diaphragm and 2-3 of vertical diaphragm.The type specimens is preserved in Department of Plant Protection,Sichuan Agricultural University(MLSAU).

A fungus was isolated from diseased rice in Guangxi,and the pathogenicity test indicated that its isolates could infect rice,corn and soybean under certain conditions.Based on microscopic morphology,other biological characteristics and ribosomal DNA-ITS sequence,the isolates obtained were identified as Sclerotium hydrophilum Sacc.,had an optimum temperature for hyphal growth at 30℃ and an optimal pH 6-9 in the culture media,and were prototrophic for thiamine.Its vegetative mycelia were similar to that of Rhizoctonia spp.The sclerotia,round and oval in shape,formed on the surface of PDA;the size of individual sclerotium was 386.4 μm×420.7 μm.Its sequence of ribosomal DNA-ITS was similar to that of S.hydrophilum(GenBank accession number:DQ875597) with 99.5% identity,and showed high homology with the strains of Rhizoctonia spp.,which was further demonstrated by the restriction analysis of an amplified fragment from 28S ribosomal DNA of these species.One specific primer pair,PS-1/PS-2,was designed from the sequence of ribosomal DNA-ITS of S.hydrophilum based on the conserved sequence determined by alignment with those of Rhizoctonia spp.By using this primer pair PS-1/PS-2,a band of 550 bp was amplified from S.hydrophilum but not from Rhizoctonia spp.

Two kinds of rapid reverse transcriptional polymerase chain reaction(RT-PCR) detection system were established in the study.The conventional RT-PCR system,in which a pair of specific primers cquctv9/cquctv10 were designed based on P20 gene of Citrus tristeza virus(CTV)and RNA polymeraseⅡgene of ci-trus was used as internal control.The other was TaqMan probe fluorescent quantitative RT-PCR system,in which a specific primer pair cquctv1/cquctv2 and TaqMan probe cquctvp1 were used and both the primers and probe were designed based on P20 gene of CTV.The detection limit for conventional RT-PCR system was 50 pg of total RNA extracted from the host infected by CTV,while that for florescent quantitative RT-PCR system was 2 fg of RNA target fragments of CTV.The sensitivity of real time florescence quantitative RT-PCR was 100-fold higher than that of conventional RT-PCR.Applying these two RT-PCR systems to detect field samples collected between March 2005 and July 2006,the results showed that both were specific and accurate.Among the 183 samples,the positive percentage of the samples detected by the fluorescence quantitative RT-PCR was higher(82.5%) than those detected by conventional RT-PCR(73.2%).

Using electron microscopy,DAS-ELISA and RT-PCR,a virus isolate(Tospo-Pha) was detected from Phalaenopsis amabilis showing yellow ringspot symptoms in Yunnan.Tospo-Pha had quasi-spherical,enveloped shape with diameters of 90 nm,reacted positively to compound antibody of Watermelon silver mosaic virus(WSMoV)/Groundnut bud necrosis virus(GBNV).The S RNA 5'-termini sequence of Tospo-Pha had highest identity(91.0%) with that of CaCV isolate Gloxinia(CaCV-Gloxinia).The Tospo-Pha clustered with other CaCV isolates in phylogenetic tree.These results indicated Tospo-Pha belonged to the genus Tospovirus.

Calcineurin as a Ca²⁺ sensor relay plays an important role in modulation of biological processes regulated by Ca²⁺.A tomato full-length cDNA,which was homologous to the sequences encoding a catalytic subunit of calcineurin(Calcineurin A,CNA),was cloned in the study.The deduced product,composed of 315 amino acids,was significantly shorter than non-plant CNA.It contained motifs conserved in CNA and two potential calmodulin-binding sites,thus was temporally named as LeCAL1(Lycopersicon esculentum calcineurin A like 1).Analysis of CNA sequence data revealed that plant and non-plant CNA differed significantly,and formed two evolutionally distanced clades.Among the known plant CNA,LeCAL1 is most similar to Arabidopsis CNA,while less homologous to rice CNA.Result of expression assay for LeCAL1 in tomato showed that Cf/Avr-dependent hypersensitive response induced LeCAL1 expression,indicating possible involvement of LeCAL1 in regulation of Cf-dependent resistance to tomato leaf mould disease.

For determing the resistance of 13 wilt-resistant black pine(Pinus thunbergii) families to Bursaphe-lenchus xylophilusa introduced from Japan,3 isolates of B.xylophilus were inoculated into the stems of 18-months old pines with bark inoculation.The resistance and histopathological reaction to nematode infection of these families were investigated.The results showed that most of 13 families were resistant,but there were significant differences in terms of the resistance to different nematode isolates.No.3,4,5,6,9,11 and 12 of these pine families had better resistant effects.The histopathological observation of family No.12 indicated that immigrating rate of the pine wood nematodes in the pine seedlings was as fast as in the controls vertically,but slower than in the control pine seedlings horizontally.In addition,pathological changes in parenchyma radial cells and parenchymarous cells around resinosis cells in wilt-resistant pine seedlings occurred later than in the control.Sampling the same stem segment at the same time,it showed that the pathological changes occurred in wilt-resistant pine seedlings more gently than in the controls.

CMV-BG infected tobacco(Nicotiana tabacum var.Samsun NN) individuals were cultured under two different temperature conditions.The virus symptom,2b gene expression and 2b gene sequence were analysed.The results showed that the symptom was much more serious on the plants under low temperature than normal conditions.The CMV-BG 2b gene sequence changed obviously and intricately,and expressed more close relationship with other CMV isolate(SF/GF/SY).In addition,although no positive selection site was found from all the clones,CMV-BG 2b gene polymorphism was higher in the plants cultured at low-temperature,and the non-synonymous mutation was also more than synonymous mutation in this group.Thus,the low temperature could enhance the 2b gene polymorphism of CMV-BG.

RNA silencing is a conserved defense system of eukaryotic cells,which operates against molecular parasites including viruses and transgenes.Temperature dramatically affects plant-virus interactions.Outbreaks of virus diseases are frequently associated with normal temperature,while viral symptoms are often attenuated and plants recover rapidly from virus diseases at high temperature.However,the underlying mechanisms of these well-known observations are not yet understood.Here,we report that 30℃ is the turning point at which Nicotiana glutinosa can recover from virus disease such as Potato virus X(PVX) and Potato virus Y(PVY) by activating system RNA silencing.The result was obtained by observing symptom development and quantifying viral protein and virus-derived small interfering RNAs(siRNAs) in N.glutinosa at different temperature.In room temperature,plants became more susceptible to viruses and virus-mediated RNA silencing was inhibited.Consistently,the levels of virus-derived siRNAs were low or never existed.In contrast,RNA silencing was activated and the amount of virus-derived siRNAs dramatically increased in lower leaves which remained symptom with rising temperature up to 30℃ or even higher,while in upper leaves which were symptomless,no siRNAs existed.All these suggested that high temperature activated RNA silencing-mediated antiviral defense in tobacco plants which resulted in symptom ease or even disappear.

Two isolates of Cucurbit aphid-borne yellows virus(CABYV) were obtained from naturally infected cushaws with yellowing symptom from fields in Kunming city of Yunnan and Wuhan city of Hubei.A pair of primers were designed based on a published CABYV sequence,and the expected fragments of about 1375 nt were amplified by RT-PCR and cloned into pMD19-T in DH5α,respectively.The recombinant clones were identified by PCR reaction and subsequently sequenced(GenBank accession number are EF488996 and EF488997).The obtained sequences started within a single open reading frame which was expected to encode a part of the RdRp of 191 amino acids by 576 nucleotides,an intergenic non-coding region(NCR) of 199 nucleotides and followed by complete capsid protein(CP) of 199 amino acids encoded by 600 nucleotides.The identities of nucleotide and deduced amino acid sequences of CP gene among CABYV-HB,CABYV-YN and other nine previously reported isolates from France,Italy,Spain,Beijing,Shanghai ranged from 93.1% to 98.5% and 91.4% to 98.5%,respectively.

The progeny population,developed by crossing V9128-1 translocation lines(Triticum aestivum-Haynaldia villosa) with susceptible cultivar MingXian169,was investigated with yellow rust race CY30.A single dominant gene was confirmed by a 3:1 segregation ratio for F₂ population.The parents and the resistant and susceptible bulks were used for screening 121 SSR primer combinations.The markers,Xgwm566 and Xgwm376,were tightly linked to YrV1(temporarily designated).YrV1 was 3.6 cM from Xgwm566,and 5.5 cM from Xgwm376.Therefore,YrV1 was located in the short arm of chromosome 3B.Two markers were tested both the genomic DNA of V9128-1 and H.villosa(one of the original parents of V9128-1).By pedigree and molecular marker analysis of YrV1,the results indicated that YrV1 derived from H.villosa was likely a novel Yr gene.

Phytophthora root rot is a destructive disease of soybean.Growing resistant cultivars is the most effective way to control the disease.Up to now,15 Phytophthora resistance genes(Rps gene) have been found,and most of them have been tagged and mapped by using molecular markers.In this study,26 soybean cultivars or lines formerly postulated to carry alleles of Rps1 locus or(and) gene Rps4 were selected to detect Rps genes by using SSR markers linked tightly to Rps1a or Rps4.By comparison of SSR markers linked to known Rps alleles in control cultivars and in combination with the former results of gene postulation,the Rps genes in selected soybean cultivars or lines were proposed.Of 26 cultivars or lines,Changnong14 was likely to possess Rps1a,Zhoudou13 and Tie95068-5 possibly possessed gene combination of Rps1a and Rps4,line 50794,Ke8924-3 and Hedou1 could carry Rps4.Rps1a was detected in 11 cultivars or lines,and line 50052 likely contained a gene combination of Rps1c and Rps3b,but it was not ruled out that these cultivars or lines possibly contained a new allele at the Rps1 locus.In addition,Rps genes in 8 cultivars or lines could not be determined and possibly contain some novel Rps genes.

Apple scab,caused by Venturia inaequalis(Cooke) Wint.,is regarded as one of the most serious diseases of apple all over the world.It is a new disease of apple on arid plateau of Weibei,Shaanxi province.The current investigation was conducted over a period of 5 years.Results showed that the number of conidia per square centimeter of apple scab lesion on fallen leaves was decreased greatly with time elapsing.The conidia in fallen leaves were colorless,transparent,with thin flake,and lost the viability before bud sprout.The average number of conidia in each bud collected from cultivars of Fuji and Gala in orchard on April 2nd 2003 was very few,but there were no viable conidia detected.The airborne ascospores and conidia of V.inaequalis were trapped with spore trapper and the results indicated that ascospores appeared before conidia.There were more than 15 days between ascospore and conidium appearance.At the same time,the date of conidia appearance was after that of symptom of apple scab.No diseased twigs were found in investigation of apple scab in Luochuan,Baishui,Changwu,Yongshou,Jingchuan,and Pingliang in arid plateau of Weibei.So,mycelium overwintered in twigs had very low probability.According to these results,the inoculum of primary infection of V.inaequalis is ascospore and conidia can not overwinter on arid plateau of Weibei.

Wheat sharp eye-spot,caused by Rhizoctonia cerealis,is an important soil-borne wheat disease in the middle and lower valley of Yangtze River.It is important to determine the category of wheat rhizosphere bacteria,characterize their biological control mechanism and effects on wheat sharp eye-spot.Bacterial strains A6,A12,B37,B40,B41 and B42 were isolated from wheat rhizosphere in Jiangyan city of Jiangsu province.These strains were determined as Pseudomonas fluorescens by analysis of their 16S rDNA sequences,physiological and chemical characters.In greenhouse,all the 6 bacterial strains decreased wheat sharp eye-spot disease index,the control efficiency of strain B42 reached to 71.67%.The analysis of secondary metabolite indicated that all the 6 strains produced neither 2,4-diacetylphloroglucinol nor phenazine.Pyrrolnitrin production related gene PrnD was found in the strain A12,B37 and B42.In strain B37,another Pyrrolnitrin production related gene PrnC was also detected.A12,B37and B42 produced siderophore,A12,B40,B41 and B42 produced proteinase,and none of the strains produced chitinase.

The 930 bp segment in 3' terminal region of Strawberry mild yellow edge virus(SMYEV) genome was amplified by 3' rapid amplification of cDNA ends(RACE).Ten Chinese isolates were sequenced,and 7 of them were the same.Nucleotide and amino acid identities and phylogenesis were analyzed between Chinese isolates and 24 isolates from other regions of the world.Sequence analysis of the 878 nt stretch within 3' terminal region of SMYEV genome showed that nucleotide acid identities ranged from 79.5% to 100%,deduced amino acid sequences of coat protein gene identity were 86.4% to 100%.Phylogenetic analysis showed that all isolates of SMYEV fell into four clades.To a certain extent,the clades were related with the geological distribution of SMYEV.Chinese isolates SY01 and SY04 lay in the same clade with European and American isolates,but formed a small separate branch.Isolates SY03 and SY02,derived from Fragaria×ananassa cv.Changhong-2 and F.pentaphylla respectively,had a far relationship with other isolates and fell into one clade.They were likely to be the special isolates that existed only in China.

Comparison of histopathological response and quantitative measurement of giant cell(GC) induced by Meloidogyne javanica in tomato root were studied under potassium-deficient(0.2 mmol/L K⁺) and replete conditions(control,6.0 mmol/L K⁺).K⁺-deficient stress did not impede the formation and maintenance of GC.The mean number of GC per feeding site as well as the mean diameter of GC did not differ between the treatments.However,the thickness of cell wall including components resulted from the accumulated polysaccharide and the length of cell-wall ingrowth increased 5-25 d after inoculation in K⁺-deficient as compared with K⁺-replete conditions.An increase of cell-wall ingrowth suggested a kind of compensational response to the potassium stress.

It have proved that wheat translocation line H9020-1-6-8-3 derived from Psathyrostachys huashanica Keng is an important resistant resource to stripe rust.To confirm the existence of resistant genes,it was crossed with susceptible cultivar MingXian 169 as male and female parent,respectively.Seedlings of parents and F₂ progeny were tested for resistance to selected CY29 of races of Puccinia striiformis f.sp.tritici from China.H9020-1-6-8-3 had one dominant resistant gene which temporarily named YrHs,whatever it was male or female parent.By using BSA method,two markers,Xgwm261 and Xgwm455 located on 2DL were found.The distance to YrHs were 4.3 and 5.8 cM respectively.The result could be used in molecular-assisted breeding.

Hyphal cell wall crude elicitor(CWE) of rice blast pathogen could induce hypersensitive response in tobacco and induce other nonhost plants to be resistant to other fungal pathogens.When corn was treated with CWE,they inhibited the infection of Exserohilum turcicum and Curvularia lunata,and when plants of capsicum and cucumber were treated with CWE,they inhibited the infection of Colletotrichum gloeospori-oides.CWE solution showed no bioactivity on spore germination and hyphal growth of the experiment fungi in vitro.Nonhost resistance induced by CWE to other fungal pathogens was not complete resistance.The induced resistant effect(IRE) increased as CWE concentration increased,however,IRE had somehow satura-ted concentration of CWE.Induced nonhost resistance by incompatible pathogen was quantitative to other compatible pathogens.The induced resistance was best at 2 or 3 d after CWE treatment,and then decreased.IRE was about 20 percent in 10 d after CWE treatment.

Colletotrichum gloeosporioides caused anthracnose in Anthurium andraeanum.Based on differences in internal transcribed space(ITS) sequences of Colletotrichum genus,a pair of species-specific primers,E1 and E2,was synthesized.The primers amplified a single PCR band of 329 bp with DNA extracted from C.gloeosporioides isolated from A.andraeanum,while other relative strains had no corresponding band.The detection sensitivity was 10 pg of genomic DNA.Using ITS1/ITS4 as the first round primers and E1/E2 as the second round primers,the detection sensitivity increased 10 000-fold to 10 fg.The detection sensitivity for the soil pathogens was 200 conidia/g soil.The PCR-based method developed here could stably and quickly detect the pathogen from water samples and diseased plant.

The bacterial wilt of Ipomoea aquatica is a new disease in Guangdong province in recent years.The incidences of diseased plants were 5%-20% in the fields,even more than 50%.Initially,one or two upper leaves of the diseased plants wilted and became gray-green.Along with the disease developing,the diseased leaves of the plants increased.And finally,the whole plants completely wilted,even collapsed.By using bacteriological identification,pathogenicity tests,16S rDNA sequence comparison and phylogenetic relationships analysis,the bacterial wilt of I.aquatica was caused by Ralstonia solanacearum.The results of pathogenicity and carbohydrate utilized test demonstrated that the tested strains of the pathogen belonged to race 1 and biovar 4 of R.solanacearum.

The pathogenicity of 22 Rice stripe tenuivirus(RSV) isolates derived from Jiangsu,Yunnan,Hebei and Shandong provinces of China were tested on 36 japonica rice varieties.According to the average infection rates of each isolate to 36 varieties,the 22 isolates were divided into 5 pathotypes:HV,SH,MV,SL and LV,and the pathogenicity order was HV > SH > MV > SL > LV.MV and SL types being 77% in the total isolates indicated that the pathogenicity of RSV to japonica rice was moderate to low.Random distribution of RSV pathotypes in different areas and years or in the same area and year implied that RSV was a mixed pathotypes naturally.The tested varieties were classified into immune(I),resistant(R),moderate resistant(MR),moderate susceptible(MS),susceptible(S) and high susceptible(HS) types,in which MS and S types being 70% but no I and HS types in the total varieties confirmed that japonica rice was susceptible to RSV but had some tolerance.Eleven japonica varieties were chosen as differential varieties for RSV pathotype identification.Some resistant varieties,which showed moderately resistant or moderately susceptible to some isolates,could easily changed to susceptible when the inoculated amounts of the small brown planthopper(Laodelphax striatellus Fallén,SBPH),the vector of RSV transmission,were increased.It was suggested to choose high resistant varieties to the given isolates on preventing the rice stripe disease,to control SBPH with chemical pesticide in time when the outbreak of SBPH populations happened and to monitor the variation of RSV pathotype at any time so as to avoid the resistance losing of rice variety.

Sequences of rDNA-ITS1 region of sweet potato stem nematode were obtained by PCR.The result of sequence analyse showed that the sequences of the nematode populations isolated from Hebei,Shandong and Anhui,had two types of genes,type "Short"(S) and type "Long"(L).The rDNA-ITS1 sequences of type "S" was 288 bp and type "L" was 466 bp.Type "L" were the populations from Shaoyao,Fexiang,Shandong province;type "S" were the nematode populations from Hebei province,Anhui province and Xinzhuang,Fexiang,Shandong province.The rDNA-ITS1 sequences homology were 82.0%-85.4% between sweet potato stem nematode and Ditylenchus destructor(AF363110),and 52.0%-52.5% between sweet potato stem nematode and D.dipsaci(AF363110).The rDNA-ITS1 sequences homology were 96.6%-100.0% among the geographic populations of sweet potato stem nematode in China.

A nationwide survey for Aphelenchida from pine wood infected with Bursaphelenchus xylophilus(Steiner & Bubrer 1934) Nickle 1970 was conducted in China.The results showed that ten species were found from 300 samples and belonged to four genera of three families based on morphological identification.Which were B.xylophilus, B.mucronatus Mamiya & Enda 1979,B.hofmanni Braasch 1998,Aphelenchoides menthae Lisetzkaya 1971,A.macronucleatus Baranovskaya 1963,Seinura tritica Bajaj & Bhatti 1982,S.elmiraensis(van de Linde,1938) J.B.Goodey,1960,S.lii Huang & Ye 2006,S.wuae Huang & Ye 2006 and Ektaphelenchidae sp.,respectively.Among which S.tritica and S.elmiraensis were new records from China.Descriptions and illustrations were provided in the paper.Population variations of these ten species suggested that the pine wood nematode was the dominate species and its occurrence would lead to a significant weakness in diversities of nematodes within pine wood.The results also indicated that further study on biological control potential of Seinura spp.to pine wood nematode was needed in China.

43 Rhizoctonia solani isolates were isolated from the infected turf-grasses of 6 species,Lolium perenne,Poa pratensis,Festuca arundinacea,Agrostis palustris,Cynodon dactylon,and Zoysia japonica,in transition zone of warm season turf to cool season turf,including Shanghai city,Zhejiang province,Shandong province,Henan province and Shaanxi province,during 2003 to 2005.Anastomosis group testing of R.solani were conducted by Parmeter's methods.The results showed that AG1-1A,AG1-1B,AG2-1,AG2-2ⅢB,AG2-2Ⅳ,AG-4 and AG-5 were confirmed in the R.solani isolates of turf-grasses from 5 provinces in China.The dominant anastomosis groups were a bit of difference among the different provinces and turf-grasses,however,AG-1 and AG-2 were the main type.AG1-1B and AG2-1 are the first reported anastomosis sub-groups of R.solani infecting turf-grasses.

Histology and ultrastructure of resistant mechanism of a new wheat material-Yilipu to Puccinia striiformis was examined by means of fluorescence microscopy,differential interference contrast microscopy and electron microscopy.The striking resistant characteristics in histology and ultrastructure were detected in the infected leaves of Yilipu as compared with susceptible wheat cultivar Mingxian 169.The main histological manifestation of the pathogen development in Yilipu wheat included inhibition of hyphal growth,delay of hyphal branching and colony formation,decrease of formation of haustorial mother cells and haustoria,at the same time,occurrence of host cell necrosis in different degrees.The observation by scanning electron microscopy demonstrated that the pathogen could enter stomatal openings by developed appressorium or germ tube both in Yilipu and susceptible wheat cultivar.Later,a series of abnormal changes occurred in intercellular hyphae,haustorial mother cells and haustoria during pathogen development in Yilipu.The cytoplasm became more electron-dense and vacuoles increased in number and in size which digested the protoplasm.The cell wall of intercellular hypha and haustorial mother cells were thickened irregularly.The mitochondria became swollen and increased in number,then hypha disintegrated gradually.The cytoplasm were degraded into central va-cuole gradually and haustorial mother cells lost their physiological function.The extrahaustorial membrane was wrinkled,the extrahaustorial matrix was widened and great amount of fibril or granular deposits accumulated there.The cell walls of hostorial body degraded gradually and perforated,and at the end,the haustorial body were malformed and necrosised.At the same time,the structural defense reactions such as formation of cell wall apposition,papilla,encasement of haustorium and necrosis of host cell were essentially more pronounced in the infected wheat leaves of Yilipu than in the susceptible one.

To demonstrate the susceptible response of soybean to Fusarium oxysporum(Fo) at the transcriptional level,gene expression profile in soybean roots during Fo infection was tested using cDNA-AFLP approach.Among approximately 1 000 transcript-derived fragments(TDFs) screened,16 were differentially regulated(9 TDFs induced and 7 repressed) in soybean roots during fungal challenge.Cloning and sequencing of the differentially-expressed TDFs indicated that 6 fragments showed homology to genes with known or putative functions,while 10 others did not show any homology to sequences with known functions.The data from this study confirms the effectiveness of cDNA-AFLP technique in detecting differentially-expressed genes during pathogenesis of soybean.

Gene chip hybridization combined with bulked segregating analysis(BSA) was used to identify ESTs involved in powdery mildew resistance or linked to the resistance gene in wheat(Triticum aestivum L.) line ‘Lankao 90(6)’.A new jacalin gene(GenBank accession number:EU035635) highly similar to Ta-JA1 was isolated from ‘Chinese Spring’,and was designated Ta-JA2.cDNA sequences of Ta-JA1 and Ta-JA2 showed 99% identity.Ta-JA2 encoded a 304 amino acid constituted peptide.Ta-JA2 protein had a typical domain for plant disease response dirigent-like proteins and a typical domain for jacalin-like lectins.Ta-JA2 expressed in leaves and stems,but almost not in roots and young spikes.The expression level of Ta-JA2 was increased in turn of young leaves,strong leaves and flag leaves.The transcribing was enhanced in seedling leaves of ‘Chinese Spring’ and a Triticum dicoccoides line by Blumeria graminis f.sp.tritici.The expression level of Ta-JA2 in ‘Lankao 90(6) 21-12’ seedling leaves was stable and relatively higher.A rectangle tree of Ta-JA2 and the similar proteins was constructed based on sequence similarity.The study provided some evolution information of the jacalin-like proteins in plants.

A population of Chinese cabbage F₂ generation including 255 individual plants was derived from the cross between resistance lines A52-2 and susceptible lines GCⅣ.A molecular genetic map of Chinese cabbage was constructed with Mapmaker/EXP 3.0 b software.A total of 124 markers(118 AFLP markers and 6 EST-PCR-RFLP markers) were mapped to 12 linkage groups,covering 683.9 cM with an average distance of 5.52 cM between loci.4 QTLs controlling TuMV-C₃ resistance at artificial inoculation were identified with Windows QTL CartographerV 2.0 software and Interval Mapping method.

Bacillus subtilis strain G3 is an active component of the biofungicide being registered to control tomato leaf mold disease caused by Cladosporium fulvum.For improvement of antifungal activity of the bacterium,acridine orange was used to produce mutants.Among the 20 mutants obtained,Ga1,Ga8,Ga12,Ga13 and Ga19 produced the mucous-type colonies on nutrient broth and PDA agar plates which were different from the colony of original strain.Inhibition tests against Cladosporium fulvum and Botrytis cinerea on PDA plates indicated that the mutants produced bigger and clear inhibition zones than the wild type G3.The Inhibition zone of Ga1 was 1.71 and 1.69 times wider than that of G3 to C.fulvum and B.cinerea respectively.MIC and EC₅₀ of the five mutants against C.fulvum were lower than that of G3 whether cultured in solid substrate or liquid.The order of the antifungal activity was Ga1 > Ga8 > Ga19 > Ga12 > Ga13 > G3.There was no correlation between the antifungal activity and cfu of the mutants,but a positive correlation between the antifungal activity and the amount of metabolites extracted with methanol,specially the amount of iturin A was observed.Mutant Ga1 showed the highest antifungal activity as about 3 times than original strain G3.Time course of iturin A production in shake flask cultures showed that Ga1 was an improved mutant with enhanced capacity to synthesize iturin A.

Bacillus subtilis 916 is an important biocontrol bacterium in controlling rice diseases.In order to further improve the growth rate and antagonistic ability of the strain and obtain high-efficiency strains,N+ of different doses were implanted into Bs-916.Antagonistic ability of the screened four mutant strains increased 15% compared with the host Bs-916 strain.The results of TLC and HPLC analysis indicated that the lipopeptides produced by Bs-916 and the mutant strains were belonged to the surfactin family.The four mutant strains produced more surfactin compared with that of the parental strain.The surfactin inhibited mycelial growth and caused the vesicle structures in the tips of hyphae,then the cell wall broken and the protoplasm leaked out on the screening plate.The enzymes of POD、PPO and SOD as indicators of resistance to plant disease were selected and compared.The activities of three enzymes were various after the rice inoculated with Bs-916 and high-yield mutant strains.The results showed that the efficacy to three enzymes by inoculating antistrains and Rhizoctonia solani simutanously was higher than that of inoculating single R.solani or antistrains.The effects of enzyme activities by four high effective mutant strains were higher than that of Bs-916.

27 Rhizoctonia solani isolates from carnation with damping-off symptoms were identified as anastomosis group AG-4 based on cultural characteristics and anastomosis in Yunnan.Sequence analysis of 5.8S rDNA-ITS of yx and tx presented 99% sequence similarity with AG-4 HGⅠtester isolate.Pathogenicity tests showed that isolates of AG-4 HG Ⅰ were pathogenic to carnation.This is the first record of damping-off of carnation caused by AG-4 HG Ⅰ in China.

Reinoculation and two-dimensional electrophoresis were performed to analyze the pathogenicity differentiation of Curvularia lunata.Resistant host inbred lines Shen135,Mo17,and 78599-1 were reinoculated(six generations) with low virulent isolate WS18.Results showed that the disease index had no significant change for the first 2 generations of inoculation.At the third generation,the incidence of disease was increased and the number of differential expressed proteins of mycelia were more than that in the first 2 generations.More than 100 differential expressed proteins were found in the mycelia of fifth generation when compared with the original one.In the experiment,10 differentially expressed proteins were identified by MALDI-TOF-MS analysis.Three proteins were related directly to the differentiation of virulence,2 were related to allergen,4 were related to the metabolism of carbon or signaling pathway and 1 was unkonwn to Curvularia lunata.

Plasma treatment is a new physical sterilization technology.In this study the teliospores of Tilletia controversa Kühn(TCK) were treated with plasma,and then observed by Scanning Electron Microscope(SEM).The results showed that the teliospores were broken into pieces.It set up some bases for research on plasma treatment of masses of wheat seeds containing teliospores of TCK.

Wheat powdery mildew(Blumeria graminis f.sp.tritici) is the one of main wheat diseases in China.Based on the internal transcribed spacer(ITS) sequences of ribosome of B.graminis f.sp.tritici,three molecular primer pairs(F1/R,F2/R and F3/R) were designed to detect the fungal pathogen of wheat powdery mildew.The species specificity of these primers was confirmed.F1/R was demonstrated a higher sensitivity than the other two primer pairs,and could detect as low as 1 pg DNA of B.graminis f.sp.tritici.Furthermore,F1/R primer pair was used to detect the pathogen DNA extracted from wheat leaves showing chlorosis and typical symptoms of powdery mildew caused by artificial inoculation with B.graminis f.sp.tritici.The preliminary results demonstrated the usefulness of this primer pair and its potential applications in efficient detection of wheat powdery mildew pathogen from leaves with latent infections at early growth stages of wheat.

Arabis mosaic virus(ArMV) had been found in the Gladiolus hybridus imported from the Netherlands by DAS-ELISA.Two pairs of primers were designed according to the conserved region of the coat protein(CP) gene sequence of Arabis mosaic virus(ArMV),and two amplified bands with expected sizes of 750 bp and 250 bp were obtained by reverse transcription polymerase chain reaction(RT-PCR).The sensitivity of nested PCR was higher than that of single RT-PCR.Analysis of the partial sequenced CP gene showed that the isolate was closed to ArMV with similarity of 99.0%-100%.All the results demonstrated that the isolated virus was ArMV.

A bioassay procedure was developed to assess the toxicity of Bacillus thuringiensis crystal protein against Meloidogyne hapla,a root-knot nematode,under laboratory conditions.Reproducibility and precision of the bioassay results were optimal when forty 2nd stage juveniles were incubated in the dissolved crystal protein solution at 25℃,pH9.0 for 7 days.The juveniles were stained with 1% KMnO₄ for 2 hours or methylene blue solution for 1 hour to distinguish living and dead ones.By the bioassay procedure,the LC₅₀ value of strain YBT-1532 crystal protein against M.hapla was determined as 0.304±0.086 mg/mL(LC₅₀±1.96SE).Moreover,the strain YBT-1532 showed toxicity to Caenorhabditis elegans,a free-living nematode.All results indicated that YBT-1532 is a toxic strain to plant-parasitic nematode,and has the potential to control plant-parasitic nematode.

The objective of the study was to develop an interaction system of soybean (Glycine max) and Phytophthora sojae in order to dissect the molecular events involved in response of the host plant to P. sojae contact and attack. Calli of 15 genotypes with differential resistance (Rps) genes were induced and sub-cultured. The virulence of 7 P. sojae isolates and their single-zoospore progenies on different soybean resistance genotypes were also tested. Finally, a soybean and P. sojae co-culture system was developed in vitro. The vigor and the defense gene expression of soybean cells at different time point after inoculation with P. sojae were analyzed. The results showed that the dynamic states of soybean cells inoculated with zoospores of compatible or incompatible P. sojae isolates were similar. Changes of expression of defense genes in soybean cells were also found in host and incompatible isolate co-culture system. The co-culture system is a good model to dissect the complex host defense response.

The diseases caused by Phytophthora hibernalis were risky and quarantinable, Here a species-specific PCR assay for rapid and accurate detection of the pathogenic oomycete P. hibernalis in diseased plant tissues was developed in the study. Based on differences in internal transcribed spacer (ITS) sequences of P. hibernalis and other Phytophthora spp., a pair of species-specific primers, 751F/752R, was synthesized. More than 19 species of Phytophthora and 6 other species of pathogens were used to test the specificity of the primers. 751F/752R amplified only a unique 616 bp band from P. hibernalis. The detection sensitivity with 751F/752R was 10 fg of genomic DNA in 25 μL recation solution. A nested PCR procedure using ITS1/ITS4 as the first-round primers and followed with 751F/752R increased detection sensitivity 1 000-fold to 10 ag. The detection sensitivity for the zoospores in distilled water was 0.5 zoospore. To detect the pathogen from the diseased plant tissues by PCR could be completed within 24 h. The results suggested that the assay detected the pathogen more rapidly and accurately than the standard isolation methods. The PCR-based methods developed here could simplify both plant disease diagnosis and pathogen monitoring, as well as guiding plant disease management.

Bacteria were isolated from diseased velveteen, cotton seed and legumen of cotton bolls, collected in a field in Kuitun and Shihezi of Xinjiang from 2006 to 2007 and tested for the ability to cause comparable boll rot symptoms in cotton fruit growth in a greenhouse. Some disease symptoms were reproduced with isolated bacteria suspension of 10⁸ cfu/mL when cotton were inoculated one week. Pathogenic isolates were identified as Pantoea agglomerans based on later morphological characterizations, physiological and biochemical reactions and 16S ribosomal DNA sequence analysis (100% nucleotide identity). This is the first report that P. agglomerans is the pathogen of cotton roll rot in China.