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.

In this study, we obtained a GmDRRP (glycine max disease resistance response protein) gene from soybean microarray data, and functionally characterized roles of its promoter during Phytophthora sojae infection. Phylogenetic and functional domain analysis showed that this gene encoded a soybean DRRP protein. qRT-PCR analysis indicated it was down-regulated by the tested hormones. Then, a promoter fragment harboring the -1,590 to +1 region (the transcription start site of GmDRRP is defined as +1 position) was isolated from soybean (cv. Williams). Its activity was determined by both transient expression assay in Nicotiana benthamiana and stable expression in transgenic soybean hairy roots. The results showed that GmDRRP promoter-derived Gus expression was rapidly induced at 0.5 hpi (hours post infection), and reached high levels at 2 hpi. We also identified a 222 bp fragment that was important for its full activities by deletion analysis. Thus, we provide a promoter that can confer Phytophthora-induced expression.

In recent years, Fusarium wilt of Dajiao has been becoming one of the most damaging diseases in Dongguan, Guangdong Province. In order to control the spread of this disease effectively, it is necessary to investigate the causal agent of Fusarium wilt of Dajiao. However, few of studies have focused on this new disease so far. In this study, a total of 31 Foc (Fusarium oxysporum f. sp. cubense)isolates from diseased tissues of banana plants were analyzed, including 12 Foc isolates from diseased Dajiao and 4 standard isolates from Australia which represent race 1, race 2, race 3 and subtropical race 4, respectively. What’s more, four non-pathogenic F. oxysporum isolates were also involved in the study for comparison. Pathogen of Dajiao was identified through pathogenicity tests, morphological studies, molecular specific detection for race 4 and tropical race 4, and phylogenetic analysis based on TEF-1α sequences. In addition, genetic relationship and pathogenic differentiation among the Foc strains were also investigated. The results showed that: (i) The wilt pathogen of Dajiao is Foc race 1 or a new lineage within Foc which is genetically close to race 1, and might be evolved from Foc race 1. (ii) The pathogen can seriously infect both Dajiao and Fenjiao, but can not infect Cavendish. Genetic differentiation was present among Chinese Foc race 1 isolates, and there were two subgroups in Chinese Foc race 1 isolates (one could only infect Fenjiao (Musa ABB Fenjiao), the other could infect both Dajiao and Fenjiao). (iii) The evolutionary relationship of Foc is complex. Both the pathogenicity tests and molecular phylogeny results showed that there may be some overlap and differentiation within the pathogens of Dajiao and Fenjiao.

In this study, the mechanism of p-hydroxybenzoic acid (pHBA) on induced resistance of flowering Chinese cabbage to anthracnose (Colletotrichum higginsianum Sac.) was investigated by inoculation of plants with C. higginsianum, along with pHBA treatment. The results showed that root system of flowering Chinese cabbage could secrete pHBA during the growth period. Exogenous pHBA exerted obvious effects on plant growth, yield formation and disease incidence of anthracnose. Appropriate concentration of pHBA could promote plant growth, enhance their resistance against anthracnose, and therefore significantly reduce disease index (DI) and improve the yield. However, autointoxication occurred in plants when the concentration of pHBA was higher, accompanied by the increased DI and reduced yield. C. higginsianum infection destroyed cell membrane, increased membrane permeability, and induced formation of pathogenesis-related proteins (PRs), such as chitinases and β-1,3-glucanases, and cell wall substances such as lignin and hydroxyproline-rich glycoproteins (HRGP). Appropriate concentration of pHBA was able to inhibit the deleterious effects of anthracnose on cell membrane permeability, induce high levels of chitinase and β-1,3-glucanase, and increase lignin and HRGP content. As a result, appropriate pHBA treatment strengthened the cell wall lignifications, increased the induced resistance of plants toward anthracnose, and prevented further invasion, spreading of the pathogen and related yield loss in flowering Chinese cabbage.

Xanthomonas campestris pathovar campestris (Xcc) causes serious black rot in all cruciferous plants worldwide. Gram-negative phytopathogenic bacteria including Xcc cause disease in host plants and trigger a HR (hypersensitive response) in non-hosts or resistant host plant through injecting type III secreted effectors (T3SEs) into host cells. T3SEs are a class of proteins secreted by the conserved type III secretion system (T3SS) which is encoded by hrp cluster. To investigate the functionality of hrp genes per se in hrp cluster, the deletion mutants for each hrp gene were constructed. The results showed that each mutation of the nine hrc genes abolished virulence in Chinese radish and lost HR induction in pepper ECW-10R. As for the nine hrp genes, only the knockout of hrpW triggered a tardy HR and decreased virulence, others lost virulence and HR induction completely. The virulence and the ability to trigger HR abolished in hpaA and hpaB mutants, while the deletion of hpa1 and hpaP reduced virulence and HR significantly. Furthermore, transcription analysis through RT-PCR demonstrated that all members of hrp cluster in Xcc 8004 were activated by hrpG and hrpX at different levels.

In order to observe the infection process of Fusarium oxysporum f. sp. cubense race 4 (FOC4) in banana root，the green fluorescent protein (GFP) was transformed into FOC4. The histopathological observation was carried out following the inoculation of banana root with GFP-FOC4. The results showed that the hyphae and a few germinated conidia（including macroconidia and microconidia）of GFP-FOC4 attached the banana root epidermis cells at one day after inoculation. The preferential colonization sites on the root surface were observed，which were the grooves along the junctions of adjacent epidermal cells. Further observation showed that hyphae，macroconidia and microconidia of GFP-FOC4 appeared in xylem vessels of the banana root at seven days after inoculation. The massive infectious hyphae of the fungal pathogen was observed extensively in the xylem vessels of banana root. This is the first report on histological observation of the infection process of FOC4 in banana root. The results obtained play an important role in exploring the pathogenic mechanism of this pathogen.

Proteomic approaches using twodimensional electrophoresis (2DE) were conducted to identify the differentially expressed proteins in rice leaves in response to methyl jasmonate (MeJA). Proteins were extracted from rice leaves at 8 h and 12 h after treatment with 0.1 mmol/L MeJA and then fractionated using PEG 4000mediated prefractionation technique before separation by 2DE. In total, twentyone proteins resolved in the 2DE gels were upregulated or downregulated in the inoculated rice leaves compared with the controls. At 8 h after treatment with MeJA, 5 and 8 differentially expressed proteins in CO39 and C101LAC were identified, respectively. Among them, U5 protein spot was specifically induced in both two rice cultivars. At 12 h, changes of 6 proteins and 5 proteins were detected in CO39 and in C101LAC, respectively. These differentially displayed proteins were successfully identified by ingel digestion, MALDITOF/TOF analysis and database searching. The protein spot U5 was identified as endo1,31,4betaDglucanase. According to protein annotations from GO database and UniProtKB database, the 21 MeJAresponsive proteins were classified into eight categories based on their putative function reported: 1) plant defense response, 2) aminoacid biosynthesis, 3) signal transduction, 4) photosynthesis, 5) photorespiratory, 6) carbohydrate metabolism, 7) protein biosynthesis and proteolysis and 8) metabolic process.

Lesion mimic mutants are characterized as the formation of necrotic lesions in the absence of pathogens, and such genetic defects often result in enhanced resistance to pathogen infection and constitutive expression of defense response genes. About 200 rice lesion mimics were found by different strategies, 52 of which had been identified by the end of May, 2009. Six genes had been cloned from these identified mutants and encoded distinct proteins including heat stress transcription factor, E3 ubiquitin ligase, acyltransferase, cytoplasmic protein kinase, zinc finger protein and ankyrin repeats protein. Although none of these proteins appeared to be directly involved in plant defense pathways, most of the 41 lesion mimics exhibited the resistance to <i>Xanthomonas campestris</i> pv. <i>oryzae </i>or<i> Magnaporthe grisea</i> and constitutive expression of typical defense-response marker genes such as callose, autofluorescence martials, phytoalexin, reactive oxygen specie, and pathogen-related genes. It was indicated that these lesion mimic mutations activated the defense system in plants, but they probably functioned in distinct signaling pathways.  Thus, extensive studies of rice lesion mi-mics will promote the better understanding  of molecular mechanisms on the crop resistance to pathogens and genetically improve resistance breeding in crops. 

To know the dominant pathogens of potato Fusarium dry pot in Gansu, tubers showing symptoms of dry rot were sampled at farmers爷storage caves in hangye city, Tianzhu, Yongdeng, Lintao, Weiyuan and Xihe county from Feb. 2006 to Mar. 2007. The pathogens were isolated by tissue isolation method, the Fusa-rium obtained were identified according to the taxonomic system of Nelson after being sub-cultured and single-spored. The results showed that the total 293 Fusarium isolates were obtained from the 12 storage caves in six sampling sites, and the dominant species were F. sambucinum and F. solani. The results also indicated that the dominant species were different in different ecological areas, for example, F. solani was the dominant pathogen in Zhangye, Tianzhu and Weiyuan, and where its isolation frequencies were 42. 6% , 42. 1% and 32. 4% respectively, and that of F. sambucinum were 14. 8% 、5. 3% and 26. 5% respectively. F. sambuci-num was the dominant pathogen in Yongdeng, Lintao and Xihe, and where its isolation frequencies were
52.1% 、50. 9% and 55. 2% , and that of F. solani were 23. 3% 、32. 7% and 20. 7% . The morphological characteristics of these two species on PDA and CLA were observed and described in details in this paper. Ac-cording to Koch爷s Postulate, the pathogenicity of the dominant pathogen were tested with mixed isolates on potato varieties Atlantic, Shepody and a local variety from Tongwei county. It was verified that both of the two dominant Fusarium species were pathogenic to potato tubers. Genomic DNA was isolated from pure cul-tures of GAUF-F12 strain of F. sambucinum and amplified with primer pairs EF-1α(EF-1H and EF-2T). The PCR product was then sequenced, and aligned in GenBank. It was indicated that there was a very close rela-tionship between GAUF-F12 and the 5 F. sambucinum isolates, and the max similarity of their sequences was 99% . DNASTAR was used to draw the phylogenetic tree of isolate GAUF-F12. It was showed that strain GAUF-F12 and the above 5 F. sambucinum isolates were in the same cluster, which was consistent with the
results of morphological identification.

To provide a theoretical basis for the use of cultivar diversity on wheat powdery mildew control, the effects of cultivar diversity on wheat powdery mildew, the yield and the protein content of wheat were studied. The genetic relationship of five wheat cultivars was studied by SSR. Mixtures of two, three, four or five winter wheat cultivars and their pure stands were exposed to mixed powdery mildew races in 2007-2008 and 2008-2009. The changes of AUDPC value, yield and protein content were investigated. The results showed that relative relation of the tested five wheat cultivars was close, which might decreased the effect of the diversity. R-S mixtures were affected significantly in combinations of two winter wheat cultivars. Efficiency was strengthened along with proportion of resistance cultivar increased. The number of cultivars had no relations with disease control effect. The effect of mixture was influenced by genetic background.The effect of cultivar mixture was decreased when there are exotic pathogen. Therefore, if the mixtures were proper, cultivar mixtures have some effect on wheat powdery mildew and no effect on yield and grain protein content. So cultivar mixtures can be a measurement for powdery mildew control.

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.

Contamination of Fusarium deoxynivalenol (DON) mycotoxin in wheat grains is toxic to human and animals. To find out the content of DON accumulation in wheat grains and its relationship with Fusarium isolate, wheat cultivar, inoculating concentration of conidia and severity of wheat scab, nine isolates of
F． graminearum clade from different areas were inoculated on five wheat cultivars at the early flowering stage. A method of single flower drip inoculation was applied for each isolate with three concentrations of 106 , 105 and 104 conidia / mL, respectively. DON contents in wheat grains were measured using ELISA test. The results showed that the differences in DON content were mainly originated from the capability of producing mycotoxins by different isolates of F. graminearum. Under the same conditions, the DON content was much higher in wheat grains inoculated with the isolates 8003 and 4020 than that with the other seven isolates. While inoculated with the F. graminearum isolates that could produce higher DON mycotoxin, the resistant wheat cultivars displayed a certain extent to reduce the capacity of DON accumulation. The concentration of inoculated conidia had impact on the disease severity of wheat scab in the field and DON content in the grains and showed a positive correlation with either disease severity or DON content.

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.

Populus alba is widely planted in northeast China and seriously infected with a rust fungus. In this study, the causal rust fungus of Populus alba was identified as Melampsora laricis based on its morphological characteristics and life cycle. Its spermogonial and aecial stages on Larix kaempferi and L.olgensis were confirmed by inoculations with basidiospores produced on P. alba.

ABC transporters play an important role in pathogenicity of fungi. In this study, 47 ABC transporter genes were retrieved from the genome of Magnaporthe grisea. The component and distribution of simple sequence repeats (SSR) within the extron, intron, 5′-UTR and 3′-UTR regions of these genes were analyzed respectively. Furthermore, effects of SSR expansion and contraction on protein structure in the gene coding regions was predicted. The results showed that component and distribution of the SSRs in these regions were different and the SSRs also distributed unevenly in regulation and function regions of these genes. Compared with other regions, the tri-nucleotide and hexa-nucleotide appeared more frequently in coding region. In addition, the G+C component was more abundant and the frequency of hydrophilic amino acids was relatively higher than that of hydrophobic amino acids in the SSRs. Depending on the variation among field isolates of M.grisea, the expansion or contraction of amino acids encoding SSR sequence were potentially affected on protein secondary structure and gene function. These data implicated that the mutation of SSR might play an important role in variation of pathogenicity-related genes.

Three to five months old Fuji apple branches were inoculated with conidia or mycelium of Botryosphaeria dothidea. Barks were sampled around lenticels or tumors from the inoculated and naturally diseased branches. The samples were cut with freezing microtomy and microanatomy conformations of tumors were examined with the microtome-sections. Observation results showed that newly formed tumors could be found just under lenticels from the branches 30 days after inoculation. The mycelia grew and expanded radially from the lenticels and the hyphae in tumors were thick and strong with circular or truncated end. All hyphae in deve-loped tumors were surround with several layers suberized host cells. The suberized cells stretched out, arranged in rings and enclosed the hyphae. A suberous layer, constructed of several layers of suberized host cells and expanded from epidermal cells, could be found just around the tumor in later stage of tumor development. The results suggested that B. dothidea infection stimulated the production of new host phloem cells and the cell suberization. The new produced cells together with the mycelia formed the tumors. The suberous layer separated the tumor tissue from health host cell and resulted in necrosis of tumor and surrounded tissues. The edge of the necrotic tumor was then lift, like saddle next year and finally peeled off. The observation suggested that tumor forming and peeling were the results of host defending reaction to the pathogen.

对湖南省百合生长期鳞茎腐烂病的病原至今未见报道。受隆回县科技局委托，我们对该县鳞茎腐烂病病原进行了形态学和分子生物学鉴定。研究结果为该病害的防治奠定了基础。

Rotylenchulus reniformis is one of the most important vegetable nematodes, and has widely host range and distribution. Based on the morphological and molecular characters, a Rotylenchulus population from Hangzhou, Zhejiang, China, in vegetable crops was identified as R. reniformis. Most morphometrics of Hang-zhou population of R. reniformis were identical with type specimens and some variations were detected. PCR Amplification and sequencing of ITS and D2D3 region of 28S RNA gene found that the two sequence lengths were 808 bp and 786 bp, respectively. Sequence alignment of ITS region of Hangzhou population and other inter-populations of R. reniformis, showed that Hangzhou population had 99.5% to 100% similarity with the three amphimitic populations, whereas 92.4% with that of one parthenogenic populations. The D2D3 region sequence of 28S RNA gene of Hangzhou population had the similarity of 99.4% to that of a R. reniformis populaiton in GenBank. The host range of Hangzhou population of R. reniformis included fruit and vegetable crops in 16 genera of 11 families. This is the first report of the R. reniformis in Zhejiang Province.

A suspected new disease of sweetpotato was observed at a number of sweetpotato production areas in Guangdong Province since 2006. The disease symptoms often appear as yellow leaves and black water-soaked rot  extending from the bottom to the top of stems  resulting in collapse and death of the entire plant. Bacterial strains were isolated from the diseased seedling stems of sweetpotato. Inoculation of sweetpotato seedlings with the isolates caused the same symptoms as naturally infected plants. The isolate H12 was identified as <i>Erwinia chrysanthemi</i> based on pathogenicity, morphological characteristics, culture patterns, physiological and biochemical reactions, and 16S rDNA gene sequences. There was no resistance on eight sweetpotato varieties inoculated with the pathogen. This is the first report of bacterial stem and root rot of sweetpoato in China.

The fungicide resistance of anthracnose in Camellia oleifera nurseries was investigated in Liuyang, Changning, and other regions in Hunan Province. The Colletotrichum gloeosporioides strains from the former two regions were highly resistant to carbendazim. After subcultured for 10 generations on fungicidefree medium, the resistant strains grew well on the medium containing carbendazim 450 μg/mL and suggesting that its resistance was stable. The βtubulin genes from the resistant and susceptible strains were cloned and sequenced.  The coding region was 1 344 bp nucleotides and predicted to encode a protein with 447 amino acids. Comparison of the βtubulin amino acid sequences between resistant and susceptible strains of Colletotrichum gloeosporioides revealed that a mutation leading to an amino acid substitution at the position 198 from glutamic acid in the susceptible strain to alanine in the resistant strain. Finally, the main morphological characteristics of C.gloeosporioides were descripted，but it could not be used to determine the resistance to carbendazim.

Rice blast, caused by Magnaporthe oryzae, is one of the most devastating fungal diseases of rice worldwide. In eukaryotes, there are two kinds of GTP binding proteins, one is heterotrimeric G protein, and the other is small GTPase protein. Small GTPase proteins have GTPase hydrolysis activity with a molecular weight of 20~30 KD, and play as a molecular switch in multiple cellular responses. Small GTPase proteins are active when bound to GTP and can thus activate the downstream proteins. When GTP hydrolyzes to GDP, small GTPase protein returns to its inactivated status. There are many proteins such as GEF and GAP, controlling the activity of small GTPase proteins in the organisms. In this study, we identified and characterized a GAP protein in M. oryzae, named MoGcs1. Targeted gene deletion of MoGCS1 showed that MoGCS1 plays crucial roles in asexual development, conidial morphology, appressorium formation and stress responses, but the gene showed no roles in growth and pathogenicity. The results indicated that MoGcs1 is a key GAP protein of the rice blast fungus.

A broad survey was conducted and infected heads of wheat were collected from 33 counties in Si-chuan, Chongqin, Hubei, Anhui, Jiangsu and Henan Provinces in 2008. Totally 433 Fusarium single spore isolates were obtained and the population and mycotoxin chemotypes had been studied through PCR assay.Four Fusarium species, F. asiaticum, F. graminearum, F. avenaceum and F. meridionale,were detected in Sichuan , while two species F. asiaticum and F. graminearum were detected in Chongqing, Hubei, Anhui and Jiangsu. In Henan Province, only F. graminearum was found. Chemotype detection results showed that Nivalenol was the main chemotype in Sichuan and Chongqing, while Deoxynivalenol was the major chemotype in Hubei, Henan, Anhui and Jiangsu. After further divided the DON chemotype strains into 3-AcDON and 15-AcDON, the results showed that 3-AcDON isolates mainly lied in Sichuan, Hubei and Jiangsu, both 3-Ac-DON and 15-AcDON isolates mixed in Anhui, and all the isolates in Henan belonged to 15-AcDON. The results indicated that F. asiaticum was the dominant specie in Sichan, Chongqing, Hubei and Jiangsu Prov-ince. It also showed that there was a clear geographical distribution of DON and NIV produced by Fusarium species. NIV was the dominant chemotype in wheat producing region belonged to the upper reaches of Yangtze River while DON was the dominant chemotype in the lower reaches. There were some relationship between DON chemotype and Fusarium species.

越橘为杜鹃花科 (Ericaceae) 越橘属 (Vaccinium) 小浆果类果树，其中的蓝果类型俗称“蓝莓”。自21 世纪以来，蓝莓这一新兴果树在中国开始了大面积的产业化生产栽培，据统计，到2008年，全国超过10个省份开始了商业化栽培，总栽培面积由2000年的24 hm2快速发展到2 000 hm2，预计未来10年内将超过10万 hm2。随着生产面积的不断扩大，各种病虫害的危害以及如何进行有效防治的问题显得越来越突出。然而，我国对蓝莓病虫害的研究很少，病虫害对于蓝莓产业发展的潜在威胁随着栽培面积的迅速增加而增大［1］。蓝莓枝干溃疡病是近年来在我国辽宁地区发生的一种为害严重的新病害。国外许多学者曾对蓝莓枝干溃疡病进行过研究报道，明确Botryosphaeria属真菌为该病病原，并对其病原学、致病性及发生流行规律进行了大量研究［2，3］，而我国尚未见相关研究报道。据此，作者采集病害枝干样品，分离获得病原菌，通过致病性测定、病原菌培养特性观察并结合分子生物学研究，旨在明确该病害的症状、病原菌种类，为其防治提供理论依据。

Rice samples showing symptoms similar to the disease caused by Southern rice black streaked dwarf virus (SRBSDV, Genus Fijivirus, Family Reoviridae) collected from three municipalities of southern Yunnan were detected by electron microscopy and RT-PCR. Electron microscopy observation of crude infected leaf extracts after negative staining revealed spherical particles of 70-75 nm, and about 411 bp fragment of RT-PCR shared 97.6%-100% nucleotide identities with reported capsid protein gene of SRBSDV isolates. The phylogenetic tree based on the partial capsid protein gene sequences indicated that the virus causing rice dwarf in Yunnan should be identified as SRBSDV.

According to the nonprotein toxin isolated by silica gel column chromatography, bioassay was testedby impregnation method in hybrid bamboo. Moreover, effects of different concentrations of toxin on the relative permeability of cell membrane, the contents of soluble protein, soluble sugar, malondialdehyde (MDA), free proline (Pro) and the activities of superoxide dismutase (SOD), peroxidase (POD), pheny-lalanineamonnialyase (PAL) were analyzed by the leaf disk method. The results showed that the typical symptoms were indicated in the toxin treatments. The relative permeability of cell membrane and the content of MDA were significantly increased. When treated with the low concentrations of toxin, there was a positive correlation betweenthe content of free Pro, the activities of enzymes and toxin. The correlation between the content of soluble sugar and the concentration of toxin was negative. However, when treated with the high concentrations of toxin, there was a negative correlation between the content of free Pro, the activities of enzymesand toxin. This demonstrated that high concentrations of toxin could destroy the tissues of hybrid bamboo and toxin played an important role in pathogenicity of A. phaeospermun.

Bacillus cereus strain B3-7 isolated from wheat roots is an endophytic bacteria, and has biological control activity against take-all of wheat incited by Gaeumannomyces graminis var. tritici. To elucidate coloni-zation mechanism of B3-7 within wheat roots, transposon TnYLB-1 was introduced into genome of B3-7 and a transposon insertion mutant library was constructed. Mutants with altered colonization numbers within wheat roots were then screened and one mutant designated as B3-7-458 with low root colonization ability was ac-quired. The flanking sequence around transposon insertion site was analyzed with reverse PCR and the results showed mota gene which involved in movement of flagella in B3-7 was disrupted by transposon insertion. The 驻mota mutant B3-7-458 showed a reduction in root colonization ability and also a reduction in biological con-trol activities against wheat take-all. Gene complementation of mota was conducted, the results showed that the colonization ability of the complemented strains and their biological control activities against wheat take-all were all restored to wild-type levels, which indicated mota gene was involved in both endophytic colonization of wheat roots and biological control of wheat take-all.

A cross between Verticillium wilt resistant tomato variety 05046 and susceptible variety 051355 was made for mapping Verticillium wilt resistance gene(s). Through inoculation test on its F1 and F2 progeny, it was proved that Verticillium wilt resistance gene was a single recessive gene.With 545 AFLP primer combinations and 101 SSR primer combinations, AFLP and SSR analysis was performed on two parents,their F2 resis-tant and susceptible bulks and F2 progeny. Three new AFLP markers and one new SSR marker linked to the Verticillium wilt resistance gene-Ve gene were identified in the study. Three AFLP markers E66M84-A,E78M84-D and E66M40-A were mapped at 10.3 cM,14.2 cM and 30.5 cM genetic distance from the Ve gene respectively. The marker SSR599 was 12.5 cM away from the Ve gene.

Sweet potato virus disease(SPVD), the most important viral disease of sweet potato, is caused by the synergistic interaction between Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV). During 2009 and 2010, vine cuttings with typical SPVD symptoms were collected from Jiangsu, Anhui, Guangdong and Sichuan Provinces to be tested for the presence of SPCSV and SPFMV. NCM-ELISA testing indicated that three samples reacted positively with SPFMV and SPCSV antiserum simultaneously. Reverse-transcription (RT)-PCR and nucleotide sequencing showed that total 10 samples were infected by both SPFMV and SPCSV. Graft transmission experiments were done by side graft. Transmissions of SPVD by grafting to virus-free sweet potato plants was achieved easily, and developed typical symptoms 30 days after graft inoculation. SPCSV and SPFMV can be detected from the diseased sweet potato plants by grafts. To our knowledge, this is the first report of SPVD in China.

An unknown disease has been breaking out and causing a great loss on Hongjv (Citrus reticulata Blanco, CV. Hongjv) since 2007 in Wanzhou, Zhongqing, China. The disease was characterized as the brown spot on affected tissues and named “brown spot disease冶temporarily. The disease occurs around a
growing season and the severe affected leaves and fruits drop quickly. To determine the causing agent, the in-fected leaves, fruits and shoots were collected from different orchards. Typical conidiospores and cultures of Alternaria and Colletotrichum were always observed and isolated from infected tissues. However, pathogenicity test showed that only the isolates of Alternaria were pathogenic to the leaves and fruits of tangerine (Ci. reticulata CV. Ponkan). Based on the study of morphology, cultural feature and partial sequence of an endopolygalacturonase gene (endoPG), the pathogenic Alternaria was identified as A. alternate (Fr. ) Keissler. The clarification of pathogen would benefit to the study on epidemiology and control of this disease.

One of main reasons for rejection of manuscript written by Chinese scientists by international journals is the inadequate or incorrect statistical data analysis. Over the last two decades, there have been significant developments in statistical methodology and implementation of statistics as computer software. However, most plant pathologists in China are still using conventional ANOVA or ordinary analysis for types of data that should be analyzed by more appropriate methods. In this short paper, we briefly introduce some statistical methods that are most likely to be appropriate for common data types encountered in plant pathology. We hope this would enable researchers to read more in a particular topic and to collaborate with applied statisticians.

An one-step dual RT-PCR method was developed for Southern rice black-streaked dwarf virus(SRBSDV) detection from host plants and insect vector white-backed planthopper (Sogatella furcifera Horvath,Hemiptera: Delphacidae), from which two cDNA fragments of the viral genome S5 and S10 were amplified
simultaneously. Two primer pairs, S5-F1 / S5-R2 (5′-ttacaactggagaagcattaacacg-3′ / 5′-atgaggtattgcgtaactgagcc-3′) and S10-oF / S10-oR (5′cgcgtcatctcaaactacag -3′ / 5′-tttgtcagcatctaaagcgc -3′), were selected from 40 primer pairs based on SRBSDV genome sequences, and amplified viral S5 ORF1 fragment (819 bp) and cp gene fragment ( 682 bp), respectively. Using total RNA extracts from infected plant leaf tissue or individual planthopper adult as templates, one step RT-PCR reaction in the conditions of annealing temperature of 53℃ with the final concentrations of 240 nmol / L S5-F1 / S5-R2 and 120 nmol / L S10-oF / S10-oR generated a similar yield of two amplicons in argrose electrophoresis analysis. Sequence analysis confirmed the correct
result of the amplification. Additionally, several commercal RNA extraction kits was proven to be fit for the template preparation, and the protocol for total RNA extraction from plant leaf tissue and individual planthopper was simplified by sample grinding direct in eppendorf tube. This method can be used for SRBSDV detection of dried or 70% alcochol soaked planthopper samples stored over one month in room temprature. Key words: Southern rice black-streaked dwarf virus; Sogatella furcifera Horvath

广东口岸从美国华盛顿输华苹果（Malus domestica）中截获可疑腐烂病果, 症状表现为果梗凹腐或萼凹腐，病部果皮暗褐色至黑色，病健交界处纹带褐色，分生孢子器黑色、颗粒状，直径0.3~0.8 mm，部分埋生或近表生, 显微镜检可见无色单胞的分生孢子。分离物生长温度-3~25℃, 最适为20℃, 经柯赫氏法则验证确认为截获病果的病原菌。Blast分析表明从分离物基因组中扩增到的ITS基因与GenBank中已知的Phacidiopycnis washingtonensis菌株ITS序列同源性达100%。经形态特征、培养性状及ITS系统发育分析, 将病原菌鉴定为苹果星裂壳孢果腐病菌（Ph. washingtonensis Xiao& J.D.Ro-gers，2005），在分类上隶属于半知菌亚门球壳孢目星裂壳孢属(Phacidiopycnis)，此截获鉴定属我国首次。迄今为止我国尚未有该病菌发生为害的报道，本文就此病菌对我国苹果和梨产业的潜在风险进行了评估分析。

Two dimensional electrophoresis (2-DE) and MOLDI-TOF-TOF MS were used to analyse the proteomic changes in leaves of the susceptible cultivar WuYu3 and resistant cultivar KT95-418 rices infected with Rice strip virus (RSV). The results showed that disease specific protein (SP) of RSV accumulated more in susceptible cultivar WuYu3 than that in resistant cultivar KT95-418. The other 25 proteins were identified successfully by MS, including RSV NS2, host proteins related to photosynthesis, dynamic balance of cellular redox state or ions and protein translation/translocation or modification. The possible functions of these host proteins in the susceptible and resistant cultivars were discussed.

The effects of benzothiadiazole (BTH) spraying on cauliflower resistance to Sclerotinia sclerotiorum were evaluated. The disease indices were investigated in susceptible and resistant varieties inoculated with mycelium agar disks to seedling leaves. The results showed that BTH significantly reduced the size of rot tissue compared with controls, and the control efficacies of BTH treatment were 81.5% and 63.8% in susceptible- and resistant- varieties respectively. The activities of defensive enzymes such as POD, SOD, CAT, PAL, and PPO were increased in BTH-treated seedlings after inoculation with S. sclerotiorum. The activities of chitinase and β-1,3-glucanase in cauliflower also increased in BTH-treated seedlings. The expression patterns of two marker genes in defense signaling pathways and four pathogenesis-related protein genes were detected using semi-quantified RT-PCR. The results indicated that BTH-induced resistance to S. sclerotiorum in cauliflower mainly through SA-dependent signaling pathway, and the up-regulated expression of  PDF1.2 showed JA/ET signaling pathway may also influenced by BTH-induced resistance in cauliflower.

Two pathovars, Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc), cause bacterial blight (BB) and bacterial leaf streak (BLS) of rice (Oryza sativa), respectively. In order to realize mutation in interesting genes of two pathovars accurately and efficiently, an insertion mutagenesis system was successfully established here with pK18mobGⅡ vector. The hrcV and hrpF mutants both of Xoo and Xoc were generated by allelic exchange between homologous fragments of the hrcV and hrpF genes, respectively. The pK18mobGⅡ, harboring different homologous fragments of hrcV or hrpF, was integrated into hrcV and hrpF gene loci. These events were verified by PCR amplification and Southern blot. 200 400 bp homologous fragments for targeted genes by pK18mobGⅡ would lead to the higher mutation efficiency. Moreover, transformation efficiency of the recombined DNA plasmids to the recipient strain by conjugation was five to hundred times of that by electroporation. Virulence assay demonstrated that the insertion mutagenesis in hrcV gene led the complete loss of pathogenecity in host rice. Therefore, this mutagenesis system would facilitate the understanding of pathogenicityassociated genes when Xanthomonas oryzae interact with rice.

In September of 2009, watermelons stored in low temperature conditions for 7 days were rotted and caused above 90% losses in Kaifeng. The fungus was isolated from diseased tissues and the morphological characteristics, pathogenicity and DNA sequence of 5. 8S rDNA-ITS were studied. The fungus was identified as Colletotrichum orbiculare based on the morphological characteristics. DNA sequence of 5. 8S rDNA-ITS of the isolate was 100% homologous with the other 5. 8S rDNA-ITS sequences of C. orbiculare in GenBank. In-oculated watermelon with this isolate could produce the same symptoms as naturally infected plants. Reisola-tion of the fungus from lesions on inoculated fruit confirmed that the causal agent was C. orbiculare which caused watermelon rot during the storage period.

The gene for resistance to powdery mildew, Pm21, derived from Dasypyrum viltosum and located on translocation chromosome 6VS. 6AL, was widely used in Chinese wheat programs. In recent years it was found that some wheat cultivars (lines) with the 6VS. 6AL translocation were susceptible to powdery mildew. In present study, a wheat 6VS. 6AL line R55 containing Pm21 was crossed with the wheat cultivars (line) Chuan-Nong 12 and R14. A complex segregation mode was observed in offspring of this cross. Three F7 families originated from the susceptible plants of the F6 lines of the cross, in which the 6VS. 6BL translocation chromosome was detected by using the molecular markers CINAU17-1086 and CINAU18-723 , was selected to
examine the different resistance expression of gene Pm21 to powdery mildew in wheat genetic background. A segregation ratio of 13 susceptible: 3 resistant was observed in the three families. In the F8 families derived from the F7 susceptible plants, 7 / 13 families exhibited susceptible and 6 / 13 families showed segregation, in which 2 / 13and 4 / 13 families fitted the ratios of 3 susceptible : 1 resistant and 13 susceptible : 3 resistant, respectively.
The results indicated that Pm21 was not expressed in some wheat lines, due to the presence of a dominant suppressor gene in the wheat cultivar (line) Chuan-Nong 12 or R14, which was designated as SuPm21. The interaction of alien genes with the genetic background of wheat genome is discussed in relation to wheat breeding program.

Guinong22, a common wheat cultivar originated from the derivative of Haynaldia villosa and Triti-cum durum, is highly resistant to all the known Chinese races and pathotypes of Puccinia striformis f. sp. triti-ci(Pst). To study genetics and develop molecular markers for stripe rust resistance gene(s), F2 , BC1 F1 and BC1 F2 progenies derived from crosses Guinong 22 / Huixianhong or Ginong 22 / Mingxian 169 were inoculated with Chinese Pst races CYR29, CYR30, CYR32, CYR33 and Su11-11 at the seedling stage under controlled greenhouse conditions. One of BC1 F2 generation was selected to screen the polymorphic marker linked to the gene conferring resistance to Su11-11. The results indicated that Guinong 22 had at least three stripe rust resis-tance genes. Two polymorphic SSR markers, Xwmc44 and Xcfa2147 were linked to the recessive gene confer-ring resistance to Su11-11 with genetic distance 5. 1 and 7. 3 cM, repectively. Based on SSR loci, the gene was located on wheat chromosome 1BL and temporarily designated as YrGn22. Gene origination, resistance and molelcular tests suggested that YrGn22 was different from the known stripe rust resistance genes Yr3, Yr9,Yr21 and Yr29 located on chromosome 1BL, and might be a new gene.

One serious disease happened on the fruit of Chinese Dwarf Cherry in Liaoning Province recently. The typical symptom was brown spot formed on the fruit surface. The spot spread quickly through the whole fruits, then the fruits were rotten. There were tomentum round shaped mildew formed on the surface of sym-ptomaticfruits. The pathogen was isolated from infected fruits. After pathogenicity tests in lab and field and re-isolation, the isolate H1 was determined to be responsible for the disease. H1 colony on PDA was 70-75 mm in diameter, with concentric rings in grayish or light brown color after 7 days incubation at 22℃ with illumination of 12 h near-UV/12 h dark. The conidia were one-celled, hyaline, lemon-shaped, （10-27） μm×（7-17） μm on PDA, produced in branched monilioid chains. The rDNA ITS sequence of islolates H1 and G1 had 100% similarity with those of Monilinia fructicola in GenBank. The amplification results with three Monilinia specific primer pairs showed that only primer pair ITS1Mfcl and ITS4Mfcl could amplify a 356 bp fragment. Based on the morphological characteristics and rDNA molecular analysis, the pathogen was finally identified as M. fructicola.

The Magnaporthe oryzae avirulence gene AvrPiz-t encodes a small predicted secreted protein (108 amino acids) without known function and mediates resistance in a gene-for-gene fashion to Piz-t in rice. Sequence analysis of AvrPiz-t revealed that its predicted mature form AvrPiz-t₉₀ consists of 4 cysteine residues, which is predicted to be involved in intra- and intermolecular interactions. To further investigate the significance of these 4 cysteine residues in the function of AvrPiz-t, a site-mutagenesis approach was utilized to ge-nerate 4 constructs encompassing mutations at each cysteine residue. Complementation tests revealed that these 4 derived AvrPiz-t mutants lost avirulence function to Piz-t, which indicated that these 4 cysteine residues were critical for the avirulence function of AvrPiz-t.