The bacterial wilt caused by Ralstonia solanacearum is a disease widely distributed in tropical, subtropical, and warm temperate regions and is difficult to control. The host range of R.solanacearum is unusually wide as a plant pathogen. This article summarized the latest research progresses of R.solanacearum including phylogenic classification, pathogenesis mechanism, genome sequence, detection and control of bacterial wilt.

Common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans, is one of the major constraints to common bean production and causes heavy yield losses and reduces the commercial value of seeds. Contaminated seeds are the primary mean of disease dissemination. This study aimed to detect the pathogens of common bacterial blight on seeds of 60 common bean samples collected from five main production regions. The pathogen colonies of common bacterial blight were isolated from seed extracts of 36 samples on MT medium by dilution-plating method, and the bacteria populations were from 2.49×10² to 5.20×10⁷ CFU per seed. The 36 representative strains were pathogenic on bean cultivar “Yingguohong” by stem inoculation. Based on PCR detection with specific primer pairs, 20 isolates were identified as X. fuscans subsp. fuscans, while 16 were identified as X. axonopodis pv. phaseoli. The results of seed detection showed that common bean seeds used in commerce and research had been contaminated with pathogens of common bacterial blight, it suggests that it is necessary to establish pathogen-free seeds production base and strengthen seed regulation.

The total DNA was extracted from strawberry leaves infected with Strawberry vein banding virus (SVBV) by CTAB method. Specific primer pair was designed to amplify the gene ORF Ⅱ of SVBV-China isolate, and then the fragment was cloned and sequenced. The result showed that the full length of gene ORF Ⅱ of SVBV-China isolate was 486 nts, encoding 161 amino acids. Comparing the sequence of gene ORF Ⅱ of SVBV-China isolate with those of SVBV-USA isolate and other members of Caulimovirus, the result indicated that gene ORF Ⅱ of SVBV-China isolate shared the highest sequence similarity (91.2%) with that of SVBV-USA isolate. The SVBV gene ORF Ⅱ was inserted into the prokaryotic expression vector pET-32a(+), and the recombinant plasmid was transformed into E. coli BL21 (DE3). The fusion protein with an approximate molecular weight of 38 kDa was obtained with IPTG induction and Ni²⁺-NTA affinity column purification. The purified recombinant fusion protein was used to immunize rabbits and obtained the antiserum of a high titer. Western blot analysis indicated that the prepared antiserum could specifically bind to purified recombinant fusion protein. ELISA was conducted with antiserum, and the protein expressed by SVBV gene ORF Ⅱ could be detected in the sap of infected strawberry leaves.

Two hybridoma cell lines (3F1 and 5G1) secreting monoclonal antibody (MAb) against Southern rice black-streaked dwarf virus (SRBSDV) and Rice black-streaked dwarf virus (RBSDV) were produced by fusing mouse myeloma cells (SP2/0) with spleen cells from BALB/c mouse immunized by a polypeptide containing 12 amino acids from the C- terminus of SRBSDV coat protein coupled with bovine serum albumin (BSA). The indirect-ELISA titres of ascitic fluids of the two MAbs were 10^-6. Both the MAbs had IgG1 isotypes with κ light chain. Western blot analysis indicated that both the MAbs could specifically react with the coat protein of SRBSDV and RBSDV. Based on the produced MAb, a dot-ELISA was established for detection of SRBSDV and RBSDV in rice planthoppers and rice samples. The detection method based on the produced anti-SRBSDV and RBSDV MAb provided technology for diagnosis, forecast and control of rice black-streaked dwarf disease.

To study the impact of the pine wood nematode (PWN, Bursaphelenchus xylophilus) invasion on the micro-structures of Pinus massoniana and P. thunbergii ,slicing section technology was used. The results indicated that the structures showed lesion characteristics during the early period of invasion and become aggravated with the time passed. For P. massoniana, parenchyma cells became lignified and cell rupture. During the second period of invasion, periderm cells, parenchyma cells of cortex and phloem all became lignified and their contents even cambial cells also became lignified. In the later period, all cells became lignified and lots of cells rupture. However, for P. thunbergii, pathogenic characteristics were the same as that of P. massoniana, but occured later and the disease degree was lighter, which indicated the difference of resistance to PWN between two pine trees. Histopathological features at the same stage were also different, it was related to the location of invasion and the distribution of PWN in the pine trees.

In the previous study, 3 virulence mutants of wheat stripe rust pathogen, Puccinia striiformis, with GUS insertion were obtained. In this study, expression of GUS gene was analyzed by histochemical staining with X-Gluc, and confirmed by specific PCR and Southern blot. The results indicated that the alien gene GUS was integrated and could inherit stably in the stripe rust genome. The pathogenicity of the 3 mutants on 17 wheat stripe rust differentials and 37 extension cultivars was different from that of the wild isolate. The inserted alien fragment resulted in the pathogenic variation of the mutants. The insertion sites of foreign gene were relevant to the virulent gene of Puccinia striiformis. This study provides a basis for the cloning of the avirulent genes.

The identification and evaluation of 24 tobacco varieties resistant to Tobacco mosaic virus (TMV) and Cucumber mosaic virus (CMV) were carried out by artificial inoculation in the field from 2010 to 2011. The results showed that 7 varieties, Coker86, Jiyan5, Coker176, CV87, Liaoyan8, CV91 and Zhongyan90, displayed resistance to TMV; 3 varieties, including Qinyan98, Shuangkang70 and C151 displayed moderate resistance to TMV; 7 varieties including Qinyan96, G80, Jinxing6007, Longjiang981, K326, Qinyan201 and NC89 displayed moderate susceptible to TMV, and 7 varieties, including G28, Yunyan97, Jingyehuang, Honghuadajinyuan, RG11, Yunyan85 and Yunyan87 susceptible to TMV. The 5 varieties resistant to CMV consisted of Coker86, Longjiang981, C151, Qinyan201 and Yunyan87; only Jinxing6007 was moderate resistance to CMV; 9 varieties including CV91, RG11, Coker176 , Zhongyan90, K326, Honghuadajinyuan, Jingyehuang , G80 and G28 displayed moderate susceptibility to CMV; 9 varieties, Qinyan98, Yunyan85, Qinyan96, NC89, Shuangkang70, Yunyan97, CV87, Liaoyan8 and Jiyan5, were susceptible to CMV. In this study, 2 varieties, Coker86 and C151, were resistant to both virus diseases. In addition, it was found that different resistant of tobacco varieties had different impacts on output and quality of tobacco. The study evalu-ated 24 tobacco varieties for resistance to the two viruses and the results could be utilized not only to provide the basis for variety selection and deployment, but also as parent materials in breeding for resistance.

Fusarium oxysporum f.sp. conglutinans (Foc) causes serious wilt disease of Brassica oleracea. The objective of this research was to investigate the mechanisms of pathogenicity variation under successive cultivation system frequently presented in China. After gaining a moderately infested field by inoculation of Foc, the cabbage was planted successively for five times and the soil samples were taken after each cultivation. Quantitative assay by soil dilution method on Komada’s medium plates indicated that the population was increased from 3.047×10⁴ cfu·g^-1 soil after the 2^nd cultivation to 1.608×10⁵ cfu·g^-1 soil after the 5^th cultivation. Comparison among the original Foc isolate and the isolates obtained after each cultivation indicated that the variation occurred in pigment production, growth rate and conidial quantity as the cultivation succeeded. Pathogenicity tests by root dipping in the 30 isolate cultures demonstrated that proportion of the Foc isolates with weak pathogenicity (DI=0-20) declined from 6.7% after the 1^st to 0 after 3^rd cultivation, in contrast with increment of proportion of highly pathogenic isolates (DI>50) from 6.7% to 16.7% after 4^th cultivation. Investigation on genetic structure of Foc populations after each cultivation using inter-simple sequence repeat (ISSR) with 11 pairs of primers indicated that population genetic differentiation was obvious after the 3^rd cultivation. Thirty isolates obtained after the 3^rd cultivation could be clustered into two distinct clades with two sub-clades under each by UPGMA analysis. However, there was no obvious corresponding relationship between the clades and pathogenicity of the tested Foc isolates.

To clarify the pathogens of potato early blight and their sensitivity to different fungicides, 180 samples of potato early blight were collected from 5 counties of Hebei Province during 2009-2011, and then isolated and purified by conventional method. Through morphological characteristics, pathogenicity test along with sequence analysis of the internal transcribed spacer region of the ribosomal DNA (ITS), two kinds of fungi were identified (A, B), with a ratio of 4:6. The sensitivity of the pathogens to different fungicides was also determined by mycelial growth rate test. Through further pathogenicity test it was demonstrated that A and B were the pathogen causing potato early blight. The preliminary morphological identification showed that A and B were Alternaria solani and Alternaria alternata, respectively. ITS sequences of A and B were amplified with universal primers of ITS1/ITS4, and compared with the GenBank database using BLAST analysis. The results showed that the nucleotide homogeneity between A and A. solani, B and A. alternata was 98% and 100%, respectively. Highly significant differences existed in the sensitivity of two pathogens to four fungicides, fludioxonil, boscalid, pyraclostrobin and difenoconazole, and no difference in the sensitivity to iprodione. Therefore, it confirmed that the pathogens of potato early blight in Hebei were A.solani and A.alternate, and their sensitivity to the same fungicide was different.

By using the crossing and haemocytometer method, the growth, spore production and other biological characteristics of Colletotrichum gloeosporioides were determined. In order to identify effective fungicides to control Colletotrichum gloeosporioides, toxicity of eight fungicides was tested by mycelial growth rate method. The results showed that the optimum temperature was 25-30℃ and the optimum pH was 5-6. The effective concentrations of the eight fungicides were obviously different. The inhibitory activities of flusilazole and tebuconazole were the highest with EC₅₀ of 0.025 7 and 0.183 μg·mL^-1, which were 1 395.55 and 195.99 times of Kresoxim-methyl, respectively. The inhibitory activities of difenoconazole and iprodione were the second with EC₅₀ of 0.187 9 and 0.434 9 μg·mL^-1. The inhibitory activities of kresoxim-methyl were the lowest.

GFP (Green fluorescent protein) is described as one of the important methods to study the interaction between target microbe and host. The shuttle vector pGFP4412, carrying gfpmut3a gene, was transformed into Bacillus subtilis B579 strain and expressed successfully. B579-gfp colonization on the surface of cucumber roots was conducted by combining antibiotics plate recovery and Laser Scanning Confocal Microscope (LSCM). The results showed that GFP-expressing B579-gfp was observed under 488 nm wavelength on the surface of cucumber roots, root bifurcated place and the pileorhiza. The B579-gfp could be recovered by antibiotics plate from three different inoculation ways (seeds soaking dipping roots and pouring roots), the numbers recovered were 4.0?10³ , 1.0?10⁴ and 2.0?10² cfu/g, respectively.

The temperature-sensitivity of 126 isolates of Puccinia striiformis Westend. (Pst) sampled from different regions and periods was tested. The results showed that there existed a great ET₅₀ (median effect temperature, which represents the temperature that is required to obtain 50％ of the maximum effect ) difference in Pst population tested, the average ET₅₀ was 24.01℃ with the highest of 27.01℃ and the lowest of 18.46℃. On the whole, the Pst population sampled from warmer,lower elevation or latitude regions showed significant adaptation to warmer temperature.

By biological identification and RT-PCR method it was found that Northern cereal mosaic virus (NCMV) was the pathogen of wheat rosette stunt disease. It was showed that 91.3% of the samples were positive in 367 symptomatic wheat plants collected from Hebei, Henan, Shandong and Shanxi Provinces of China in 2010. The NCMV N, P, M, G and L gene sequences were amplified and obtained by RT-PCR with the primers designed according to the target gene. BLAST analysis revealed that the identity of nucleotide sequences derived from Hebei, Henan, Shandong and Shanxi isolates was 98.9%-99.3% and greater than 99% of deduced amino acid sequences. The identity of nucleotide and deduced amino acid sequences between these Chinese and Japanese NCMV isolates was 92.2%-94% and 98.6%-99.4%, respectively. Sequence analysis showed a high level of sequence conservation among NCMV isolates. However, there was a small variation between China and Japan isolates.

A species-specific PCR assay was established for rapid and accurate detection of the oomycete pathogen Phytophthora tentaculata in diseased plant tissues and infected soil. A pair of species-specific primers Pt1/Pt2 were designed on the basis of Ras-related protein (Ypt1) gene sequences of the Phytophthora species. PCR amplification with the Pt primers resulted in a 386 bp product only from isolates of P. tentaculata. The detection threshold with Pt primers was 100 pg of genomic DNA. A nested PCR procedure was developed using Ypt1F/Ypt1R as the first-round amplification primers and Pt1/Pt2 as the second-round primers, which increased the detection sensitivity 100-fold to 1 pg. PCR using these Pt primers can also be used to detect P. tentaculata in naturally infected plant tissues and soil. The PCR-based method developed in this study provides a rapid and sensitive tool for detection of P. tentaculata.

The total 73 different tobacco virus disease samples collected from different regions in Yunnan were detected with electron microscopy, DAS-ELISA, immunostrip test and multiplex RT-PCR. The results showed that the tobacco virus diseases were serious in Yunnan Province. 10 kinds of viruses were detected in the experiments. The viruses were more at the northeast and central part, such as Chuxiong and Wenshan, than the north part of Yunnan. The results showed that main viruses were Tobacco mosaic virus(TMV), Cucumber mosaic virus (CMV), Potato virus Y(PVY), Tobacco etch virus (TEV) and Tobacco vein banding mosaic virus(TVBMV). The detection results showed there were nine types complex infections. The complex infection sample was 31.50% among the total testing samples. The main type of complex infection was that TEV and TVBMV, occupied 34.78% among the all combination.

The 3′-terminal genome of 25 Apple chlorotic leaf spot virus (ACLSV) isolates from sand pear (Pyrus pyrifolia) in Wuhan and Hangzhou, and 2 isolates from peach in Wuhan and Xian were amplified by RT-PCR. The sizes of cloned fragments were 674, 679, 680 and 686 bp, respectively, including partial coat protein (CP) gene and 3′-terminal untranslated region (3′-UTR). Phylogenetic analysis on nucleotide (nt) sequences indicated that ACLSV isolates obtained were clustered into two branches or sub-branches in the sub-group I-1 of the group I. The ACLSV isolate hz-48 from sand pear in Hangzhou showed low identities with the other isolates from China, ranging from 83.5% to 87.5% (nt) and 82.6% to 86.2% (amino acid, aa), and was grouped into a separate sub-branch of sub-group I-1 in the phylogenetic tree. The aa multiple alignment of sequenced partial CP revealed that ACLSV isolates showed high variability at the N-terminal part of CP region overlapped with the MP region and relatively conserved at the C-terminal part, whereas the variation positions were also presented in C-terminal part of CP region from the isolate hz-48 analyzed in this study.

Tomato yellow leaf curl virus (TYLCV) induces severe disease on tomato and was found in Beijing in 2009.In 2010 and 2011,53 tomato samples from 5 counties were collected and detected using a pair of primers PA/PB designed according to the specific sequence of the whitefly-transmitted geminiviruses. The results showed that target fragment (about 500 bp) could be detected in 30 samples with typical yellow leaf curl symptom. Sequence analysis of the fragments of seven typical samples confirmed that those samples were infected by TYLCV. Complete genomic sequences of 4 TYLCV isolates（BJDXXY,BJFS02,BJFS03 and BJMY2231）were obtained with two pairs of TYLCV-specific primers,TJ-F/TJ-R and TY-F/TY-R.Their genomes all contained 2 781 bp nucleotides encoding six potential proteins and was most closely related to TYLCV-Israel strain (higher than 98% sequence identity).Phylogenetic analysis based on the DNA genome sequence showed that BJDXXY,BJFS02 and BJFS03 were more related to reported isolates of TYLCV-Israel in Hebei Province (TYLCV-HBLF4) and Shandong Province (TYLCV-SDSG）in China,and BJMY2231 is more closely related to the isolates in Shanghai and Jiangsu Province (TYLCV-JSNJ1).

Malvaiscus arboreus leaf curl disease in Guangdong is a new disease. The diseased plants exhibits leaf curling upwards, vein swelling and vein dark green. The results of PCR detection indicated that the diseased plants were infected by a begomovirus. Virus isolate GD11 was obtained from M. arboreus leaf curl disease in Guangzhou, Guangdong Province. The complete nucleotide sequence of DNA-A was determined to be 2 737 nucleotides, encoding six potential ORFs. It was typical characteristics of Begomovirus. Comparisons showed that the DNA-A of GD11 had more than 89.0% sequence identity with all other isolates of Cotton leaf curl Multan virus (CLCuMV), and more than 99.0% sequence identity with isolates G6, Okra06 and GX1. The virus was also associated with satellite DNA β molecular,which contained 1 348 nucleotides. Pairwise comparison indicated that the DNA β of GD11 had more than 85.0% sequence identity with CLCuMV DNA β, and more than 99.0% sequence identify with isolates G6, Okra06 and GX1. These suggested that isolate GD11 infecting M. arboreus in Guangdong belonged to CLCuMV. Moreover it was most closely related to the isolate G6 infecting Hibiscus rosa-sinensis, the isolate Okra06 infecting Hibiscus esculentus in Guangdong and the isolate GX1 infecting Gossypium hirsutum in Guangxi. The paper is the first report on CLCuMV and its DNA β complex infecting M. arboreus.

The venom allergen-like protein gene of Bursaphelenchus xylophilus (Bxvap2) was optimized using the overlap extension PCR technique for expression in Escherichia coli. It was subsequently cloned into pET-29b (+) vector and the fusion protein was highly expressed in E. coli BL21 (DE3) in soluble form which covered 33.5% of total cellular proteins. After purification through affinity Ni-NTA column, the fusion protein was further identified as BXVAP2 by mass spectrometry (MS). White rabbits were immunized with BXVAP2 protein. The sensitivity of polyclonal antibody was 5.4 ng穖L^-1 (the titer was 1:1 360 000) tested by indirect ELISA. This result will be an important basis for tissue localization and functional study of BXVAP2 protein of B. xylophilus.

In order to reveal the participation of microtubules in the interaction of nonhost pepper cultivar “A11” and Colletotrichum orbiculare, the defense reactions (papilla formation, oxidative burst and hypersensitive response) and the penetration process were investigated histochemically after microtubule depolymerization of the pepper leaves. The results indicated that the depolymerization of microtubules significantly weakened the production of the papilla formation and H₂O₂ burst on pepper leaves, and allowed successful penetration of the non-adapted C. orbiculare. It was concluded that microtubules participated in the nonhost resistance and the polymerization of microtubules was significant in nonhost resistance of pepper.

V2 gene of Tomato yellow leaf curl virus (TYLCV) was amplified by PCR from the diseased samples collecting from Jiangsu Province and cloned into pMD18-T vector. The sequencing result showed that V2 gene had 351nt and encoded 115 amino acids with a Mr of 13 kD. Sequence comparison showed that the V2 gene shared 100% sequence identities with XH2, an isolate of TYLCV reported in Jiangsu in 2007. V2 gene was inserted into prokaryotic expression vector pET32a to produce recombinant plasmid pET32a-V2, and the recombinant plasmid was introduced into Escherichia coli strain BL21 (DE3). SDS-PAGE analysis confirmed that V2 fusion protein was expressed after induction by IPTG. The recombinant V2 protein was purified with Ni⁺ NTA affinity column and used to immunize rabbits for production of polyclonal antibodies. Finally polyclonal antibody, anti-V2, was obtained with titer above 1:655 360. The V2 protein was successfully detected by western blot in prokaryotic expression products and in infected tomato by dot immunobinding assay with anti-V2. Based on the antibody, further researches on the function of V2 protein could be carried out.

Bacterial strain CAB-1 was isolated according to its chitinolytic activity and antifungal activities against plant pathogens including Botrytis cinerea in virto. Strain CAB-1 was identified as Bacillus atrophaeus based on the biochemical characters, sequences analysis of 16S rDNA and gyrB. Through sequence analysis and function predicting based on it whole genome, two chitinase genes were located and cloned from strain CAB-1. These two cloned chitinase genes were ligated into the prokaryotic expression vector and fusion proteins were induced. Chitinase activities of the induced protein Chit1 and Chit2 were testified by plate transparent circle method. In the meantime, only Chit1 protein showed antifungal activity against B. cinerea. The expression condition of Chit1 protein was optimized. The results showed that incubating at 30℃ for 24 hours in shaker and induced by IPTG of 0.2 mmol/L to 1.0 mmol/L was recognized as the optimized condition for Chit1 protein production.

The lec-s gene encoding soybean lectin was inserted into transgenic vector pBI121. The leaf discs from tobacco were transfected by Agrobacterium tumefaciens strain EHA105/ pBI121:: lec-s. Kanamycin-resistant transformed plants were obtained. PCR and RT-PCR analyses confirmed successful integration of the foreign gene into the genome of the T₁ generation tobacco plants. Bioassays revealed that the resistance of transgenic plants to Tobacco mosaic virus (TMV) was increased; lesion numbers on leaves caused by TMV were markedly reduced in transgenic plants comparing with the controls. Quantitative RT-PCR analysis indicated that four defense-related genes, PR-1a, GST1, Pal, and hsr515, were up-regulated in transgenic lines inoculated with TMV. The up-regulations of these defense-relate genes were not observed in leaves of control plant after inoculation. The results suggested that lec-s gene might play a role in the regulation of plant defense responses through the induction of downstream defense-related genes after the recognition of microbial pathogens, thus the transformed tobacco plants with lec-s gene could enhance the resistance to TMV.

Stripe rust,caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases of wheat throughout the world.M852-1, a translocation line derived from hybridization and cross between Triticum aestivum and Leymus mollis,is resistant to the current prevalent Pst races in China.To identify and map the gene(s) conferring resistance to stripe rust,Pst races (CYR29, CYR32, CYR33 and Su11-7) were selected to test the F₁, F₂, F₃ and BC₁ generations derived from the cross M852-1/Mingxian 169 at the seedling stage. The gene conferring resistance to CYR32 in M852-1 was mapped by linked SSR (simple sequence repeat) markers. The genetic analysis showed that one dominant resistance gene to CYR29 and one recessive resistance gene to CYR32, CYR33 and Su11-7 respectively were estimated for M852-1. By using SSR to analyze the 144 individuals in the F₂ segregating population, three markers on chromosome 2BS (Xbarc124, Xbarc200 and Xgwm429) were identified and linked with the resistance gene YrM852 (temporarily designated) at the distance of 6.3, 5.6, 9.7 cM, respectively. Furthermore, based on the source of the gene YrM852, molecular detection and chromosome location, YrM852 might be a novel stripe rust resistance gene.

The mycelium growth rate method was used to test the sensitivity of 87strains of Pyricularia grisea to isoprothiolane from different distracts in Liaoning Province from 2009 to 2010. The results showed that the EC₅₀ of the strains to isoprothiolane ranged from 0.35-7.01 μg/mL with a difference of more than 20 times. The sensitivity of strains isolated in 2009 to isoprothiolane was higher than that in 2010. According to gaussian distribution theory of wildly sensitive strains from field, the sensitive base-line of Pyricularia gresea isolates to isoprothiolane was (1.77±0.80) μg/mL in Liaoning. Except one moderately resistant isolate existed in rice producing areas of Tieling, most of the isolates were low resistant to isoprothiolane. The sensitivity of strains belonging to different physiologic race groups to isoprothiolane had no significant difference.

The PopW, a new harpin protein, was isolated from the bacterium Ralstonia solanacearum ZJ3721and showed induced resistance to various plant diseases. In this study, the biocontrol efficacy of PopW against cucumber downy mildew caused by Pseudoperonospora cubensis was investigated and evaluated. The PopW at the concentration of 250 mg/L obtained the best biocontrol efficacy of 42.85% than the other concentration at the 15^th day after pathogen inoculation under the greenhouse experiment. Meanwhile, PopW（250 mg/L）promoted the growth of cucumber and increased the content of chlorophyll in leaves of the plant. In the field experiments, the PopW with the same concentration was applied every 15 days and used three times in 2010. The biocontrol efficacy reached 41.87%, 48.36%, 53.21% and 50.85% at the 8, 25, 35 and 48 d after the first treatment of PopW, respectively. In 2011, the same treatment was applied every 10 days and the biocontrol efficacy reached 47.07%, 48.17%, 50.59% and 54.48% at the day of 8, 15, 22 and 27 d after the first application of PopW, respectively. The results indicated that the PopW had the potential to be an effective biocontrol agent against Pseudoperonospora cubensis and the resistance induced could keep 10-15 days, even more. Furthermore, PopW increased the yield with 33.01% per individual plant and significantly improved the quality of cucumber fruit with increased content of soluble sugar, soluble protein, free amino acids and vitamin C with 18.07 mg/g, 6.80 mg/g, 60.20 mg/100 g, 68.27 μg/g, in PopW treatment and 10.21 mg/g, 5.30 mg/g, 59.06 mg/100 g and 49.55 μg/g in control respectively.

To produce the antiserum of ratoon stunting disease (RSD) of sugarcane, RSD bacteria were isolated from the cane juice of infected sugarcane plants using the improved SC medium, and then identified according to PCR detection results. ELISA was used for the titer determination, and Tissue Blot Immunoassay (TBIA) detection was done to compare the detection capacity between homedade RSD antiserums and the imported one from USA. The results showed that the isolated pathogen is similar to the reported Leifsonia xyli subsp. xyli (Lxx) in morphology. A specific PCR product with the molecular size of 438 bp was also amplified from both bacteria. The ELISA titer of antiserum against Lxx was greater than 1:256 000. The TBIA detection results using homemade RSD antiserum were consistent with those detected by RSD antiserum from USA.

The effects of six kinds of fertilizer on maize stalk rot were studied in field condition. The results showed that potassium fertilizer greatly strengthened maize resistance to stalk rot, and the control effect was correlated positively with dosage. KH₂PO₄ and ZnSO₄ also showed obvious effects, which were 61.2% and 65.5%, respectively. The control effects of calcium magnesium phosphate fertilizer and farmyard manure were 25.2% and 34.5%, respectively. There was no difference between urea with normal dosage and no-fertilizer control. Furthermore, ICP-AES was employed to detect the mineral elements variation between healthy and diseased maize. The results showed that eight of ten tested elements displayed lower content in diseased maize stem than that in healthy control and six elements in root were found lower than that of healthy maize.

Mating types of 108 Phytophthora capsici isolates collected from Jiangxi Province were tested. The results showed that no oospore was produced while the isolates were cultured with A₂ isolate, but oospores were observed while the isolates were cultured with A₁ isolate. It indicated that P.capsici population from Jiangxi was composed of A₂ mating type. The sensitivity to cymoxanil of 108 Phytophthora capsici isolates collected from different areas of Jiangxi were determined by mycelia growth inhibition method. The result showed that EC₅₀ values ranged from 1.227 6 to 33.260 8 μg/mL, with an overall mean of 12.991 0±0.691 4 μg/mL, and EC₅₀ of the most insensitive isolate was 27.09 times of that of the most sensitive isolate. There existed great sensitivity differenc to cymoxanil between isolates from different regions.The isolates from Jian county had the lowest ave-rage EC₅₀ value 17.873 2 μg/mL, and the highest average EC₅₀ value 6.693 4 μg/mL was from Jiujiang. There also existed great sensitivity differenc to cymoxanil between isolates in the same regions. EC₅₀ of the most insensitive isolate was 8.46 times of that of the most sensitive isolate from Gaoan.

The objective of this study was to identify the roles of miR156 family in different abiotic surroundings in wheat ( Triticum aestivum L), reveal the cross-talk of members of miR156 family in abiotic regulatory networks and better understand the mechanisms responsible for abiotic stress tolerance. Five members of miR156 family were found in wheat through Solexa high-throughput sequencing. The Northern blot results showed that the expressions of miR156a and miR156d^* were up-regulated in UV-B stress, but the expression pattern of miR156c^* and miR156b^* were significantly down-induced after 24 hours with cold and UV-B treatment. Furthermore, the qRT-PCR analyses showed the expressions of miR156 family were different after treated by every abiotic stress. These results indicated that some members of miR156 family may play different roles in response to abiotic stress.

The objective of this study was to detect the effect of high temperature stress on the expression of HSP70 gene in Blumeria graminis f. sp. tritici. The cDNA sequence of HSP70 gene was cloned using RT-PCR and RACE. The obtained cDNA sequence contained a 1 947 bp open reading frame (ORF) and encoded a sequence of 648 amino acids residues. The molecular mass was estimated as 70.5 kDa and isoelectric point (pI) 4.84. The gene contained the signature sequences of HSP70 family. Real-time quantitative PCR was used to analyze the expression of HSP70 gene of B. graminis f. sp. tritici after the treatments of heat shock (28℃) in different time. The results showed that the mRNA expression of HSP70 gene of B. graminis f. sp. tritici was significantly up-regulated after heat shock at 28℃. The expression level of HSP70 gene reached the maximum (11.6 times of the control) after 60 minutes, and then decreased. It was inferred that HSP70 gene might play an important role in B. graminis f. sp. tritici to high temperature.

A new disease was found in roots and rhizomes of Rosmarinus officinalis L.. Based on the morpho-logy, pathogenicity and the sequences of ribosome rDNA-ITS, the pathogen causing R. officinalis L. root rot disease was identified as Rhizoctonia solani K黨n. According to the test results of hyphal fusion with international standard isolates of Rhizoctonia, it belonged to anastomosis group AG-4.

Fifty-eight isolates of Rhizoctonia solani were isolated from tobacco target spot disease samples collected from tobacco growing areas in Liaoning Province. The test results of anastomosis groups (AGs) by glass slide fix position mating method showed that all isolates of R. solani belonged to AG-3. The rDNA ITS sequence of the R. solani strain YC-9 was amplified and sequenced by using the universal primers ITS1and ITS4, and compared by nucleotide BLAST with other nucleotides in GenBank. It was showed that the ITS sequence of YC-9 (653 bp) was completely identical to that of the R. solani AG-3 isolate from tomato foliar blight. The results provide important basis for further investigation of tobacco target spot disease.

Five leaf samples from watermelon plants with mosaic symptom in Shaoyang County were proved to be CGMMV-positive by RT-PCR detection using one pair of specific primers. The sequence of RT-PCR product (CGMMV-SY) was submitted to GenBank and showed identical to those of CGMMV coat protein genes in nucleotide databases after BLAST. The seeds of a rootstock variety widely used from Beijing were also detected CGMMV-positive and the RT-PCR product (CGMMV-JX) was of the same sequence as CGMMV-SY. They shared 100% nucleotide identities with some CGMMV isolates of Liaoning and Korea. It suggested that CGMMV occurred in watermelon crop in Hunan, might be originally transmitted by grafting with rootstock infected with CGMMV.

The sulfur-containing amino acid, methionine, is not only a key component of protein, but also displays many essential functions in cellular metabolism through its main derivative S-adenosylmethionine (SAM). According to the researches on methionine biosynthesis in Saccharomyces cerevisiae, Neurospora crassa and Aspergillus nidulans, we sketched the methionine biosynthesis pathway in fungi, and summarized biological functions of key enzymes and regulation mechanism of the pathway. Information from this review may make a contribution to further research of methionine biosynthesis in plant pathogenic fungi and to the development of new fungicides.

Plant aquaporin proteins basically mediate water transport through cell membranes, and also affect plant-microbe interactions and plant defense responses. Molecular mechanisms that underlie the dual function are unclear. Recently, the rice and Arabidopsis aquaporins OsPIP1; 2 and AtPIP1; 4 interact with Hpa1, a protein secreted by type Ⅲ pathway in Xanthomonas oryzae pathovars oryzae and oryzicola, which cause bacterial blight disaese and bacterial leaf streak disease of rice, respectively have been determined. When applied to plants or produced in transgenic plants, Hpa1 localizes to the apoplast and induces hydrogen peroxide generation in the same cellular location. The generation of hydrogen peroxide is dependent on the NADPH oxidase located at the plasma membrane. In response to Hpa1, moreover, the apoplastic hydrogen peroxide translocates to the cytoplasm with subcequent effects of enhancing plant defense responses to bacterial pathogens. According to established models in regard to the topological structure of aquaporins, the performance of bacterial type Ⅲ secretion, and subcellular trafficking of hydrogen peroxide in plants, it is necessary to identify the functional domain for OsPIP1; 2 interacting with Hpa1, and elucidate molecular features and structural basis of the OsPIP1; 2-Hpa1 interaction. Signal transduction triggered by the molecular interaction may be linked with the role of OsPIP1; 2-Hpa1 interaction in modulating translocation of apoplastic hydrogen peroxide to the cytoplasm, thus connecting the signal translocation with defense responses in rice. The OsPIP1; 2-Hpa1 interaction may also play a role in facilitating the translocation of X. oryzae type Ⅲ effector proteins from the bacterial cell to the plant cell because Hpa1 has been suggested as a candidate of tyep-Ⅲ effector translocators. With this hypothesis, studies are to further reveal regulatory mechanisms of plant-pathogen interactions, offerring a significant extension of aquaporins’ functions over what we have known up to date.

The viable but non-culturable (VBNC) state is a survival strategy in response to harsh environmental conditions. The VBNC state of five species of plant pathogenic bacteria has been reported. The specific physiological state of bacteria has leaded to some changes of methodology and will influence the traditional research based on culture in bacteriology. This review describes the VBNC state of plant pathogenic bacteria, including the inducing factors, the detection methods, the resuscitation of VBNC bacteria and its pathogenicity. Some prospects of the VBNC state are provided.

To analyze the development trend in the research of rice blast objectively in the world, and provide the reference for the researchers and the strategy makers, a bibliometrics study on the top ten countries, research institutes, journals and high-cited authors in the field of blast indexed was carried out by the Web of science during 1910-2011 using regular searching way. The results indicated that among the all nations, the top 10 ones were the U.S., Japan, China, Philippines, South Korea, Germany, France, Britain, India and the Netherlands. Philippine Scholars and the International Rice Research Institute (IRRI) had the clear advantage on the research of blast. The rank of the journals, research institutions and authors were overwhelmingly dominated by the U.S., Zhejiang University and Chinese Academy of Sciences were in the top 10 publishing institutions. The advantage of blast research in china was the high quantity but quality, so the lack of high-level research papers on blast in china should be given high concern. The hot area of the blast research was the resistance of the gene and QTLs etc. Above evidence further indicate that Web of Science,as the high-level data base of rice disease research, prefers top quality and English articles. Therefore, other databases should be supplemented if we want to learn the development of the research articles from Non-English countries.

The morphology and germination of uredospores, as well as infecting structure of Melampsora pruinosae in Populus euphratica and P. pruinosa were studied by means of dry examination, microscopy, and ultra-structure observation. Results showed that the uredia and uredospores of M. pruinosae on P. euphratica and P. pruinosa appeared to be similar in morphology and structure. The uredia revealed hemispherical or half ellipsoidal masses with orange yellow or golden yellow color on both sides of diseased leaves. Uredospores were unicellular and thick-walled spherical or ovoidal shape, transparent and orange yellow, scattering on both sides of diseased leaves. There were no significant differences in four parameters of uredospores shape, including length, width, height of projection, and intervals of projections. The hyphae, formed by germ tubes from germinated uredospores, infected the leaves through stomata, and expanded in the leaves in both P. euphratica and P. pruinosa.

The fungal genus Verticillium contains two well-studied species of widespread and common soilborne plant pathogens, V. dahliae and V. albo-atrum. Those two species are also listed as the quarantine pests of imported plants in China. Diverse isolates of the plant pathogenic Verticillium spp, including V. albo-atrum, V. dahliae, V. dahliae var. longisporum, V. tricorpus, V. nigrescens and V. nubilum collected from China and CBS, were studied by biology and rDNA-ITS analysis to differentiate the quarantine Verticillium spp. from others. Results showed that although there are distinct resting structures among different Verticillium spp., some isolates have lost the ability to produce the resting structure. In the temperature test, all the V. albo-atrum did not grow at 30℃, while others Verticillium spp. grew well under 30℃. The rDNA-ITS fragments were sequenced from isolates of the five species of Verticillium. The sequences ranged from 539 to 559 bp in length. Analysis of these sequences with the related sequences deposited in the NCBI database showed the six investigated Verticillium species clustered into nine clades. V. albo-atrum, V. dahliae and V. dahliae var. longisporum were phylogenetically close. This study suggests that combination of the biological characteristics and the rDNA-ITS sequence analysis can be used to differentiate the quarantine Verticillium spp. from others species of Verticillium.