Studies on metalaxyl-resistance inheritance of Phytophthora boehmeriae causing cotton boll blight
CHEN Fang-xin1, GAO Zhi-mou1, QI Yong-xia1, WU Hong-xing2, WU Xiang-hui1(1 Department of Plant Protection of Anhui Agricultural University, Hefei 230036, China£» 2 Gaoshi Station of Agro-Technical Extension, Wangjiang 246260, China)
Abstract: The resistance inheritance of the metalaxyl-resistant mutants(Mtr) of P. boehmeriae Sawada obtained by metalaxyl-induction was studied in vitro. The results showed that the tested pathogen deve-loped the resistance to metalaxyl easily, and that the resistance level of Mtr mutants was over 5 161.ª±3 times higher than that of their sensitive parental isolates to metalaxyl. The resistance of some mutants to metalaxyl could steadily inherit in their asexual and sexual generations, but the resistance of some mutants to metalaxyl displayed obvious variation in the first and second single-zoospore progenies, even lost completely. It was suggested that metalaxyl-resistance of P. boehmeriae causing cotton boll blight might be controlled by cytoplasmic genes.
Key words£º Phytophthora boehmeriae; metalaxyl; fungicide-resistance; inheritance

Production of monoclonal antibodies to Rice stripe virus and application in virus detection
WANG Gui-zhen1, ZHOU Yi-jun2, CHEN Zheng-xian1, ZHOU Xue-ping1*(1Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China£» 2Institute of Plant Protection, Jiangsu Academy of Agricultural Science, Nanjing 210014, China)
Abstract: Four hybridoma cell lines secreting monoclonal antibodies (MAbs) against Rice stripe virus (RSV) were produced by fusing mouse myeloma cells (SP2/0) with spleen cells from BALB/c immunized by the RSV particles. The titres of ascitic fluids of four MAbs ranged from 1¡Ã80 000 to 1¡Ã5 120 000 tested by indirect ELISA. The result of Western blot showed that the four MAbs could react with the 35 kDa coat protein specifically. The four MAbs could detect RSV in plant sap with 1¡Ã2 560 dilution by indirect ELISA successfully. The MAbs didn't cross-react with other tested plant viruses. Indirect ELISA was then used for detection of RSV in Laodelphax striatellus Fallen collected in Jiangsu Province. The proportion of the viruliferous Laodelphax striatellus ranged from 12.5% to 41.5%.
Key words£º Rice stripe virus; monoclonal antibodies; ELISA; Laodelphax striatellus

Biological characteristics of Gliocladium catenulatum HL-1-1 mycoparasited on Sclerotinia sclerotiorum
MA Gui-zhen1£¬2£¬4, LI Shi-dong1£¬ ZHANG Yong-hua1£¬ XIE Bing-yan3, LU Guo-zhong4£¨1 Biological Control Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China; 2 Hebei Normal University of Technology & Teachers, Qinhuangdao 066004, China; 3 Institute of Vegetable and Flower, Chinese Academy of Agricultural Sciences, Beijing 100081, China; 4 Shenyang Agricultural University, Shenyang 100161, China£©
Abstract: Biological characteristics of G. catenulatum HL-1-1, a superior isolate for biological control of plant fungal diseases were studied. The results showed that medium made from powder of fungal sclerotia was optimum for the growth of this isolate, while PDA was optimum for its sporulation. Sucrose was optimum C source and KNO3 optimum N source for its growth. Soluble starch was optimum C source and beef extract optimum N source for its sporulation. Temperature ranged from 25 to 30¡æ was optimum for its hyphae growth and spore germination, while 25¡æ was optimum for sporulation. Spores could not germinate below 5¡æ or over 40¡æ. Lethal temperature of spores was 52¡æ. Optimum pH was 5.0 for hyphae growth and 6.0 for sporulation. Dark condition enhanced hyphae growth and light was good for sporulation. Extract of sclerotia promoted spore germination of the isolate£¬but D-glucose inhi-bited. The data provide basic information for further studies on fermentation, formulation and delivery techniques of the isolate.
Key words£º Gliocladium catenulatum; biology; Sclerotinia sclerotiorum; mycoparasitism

Cloning and prokaryotic expression of a viral binding protein gene (groEL) from endosymbionts in Bemisia tabaci
TAN Zhou-jin1£¬2, XIE Bing-yan1*, XIAO Qi-ming2, YANG Yu-hong1, FENG Lan-xiang1 (1Institute of Vegetable and Flower, China Academy of Agricultural Sciences, Beijing 100081, China£» 2College of Plant Protection, Hunan Agricultural University, Changsha 410128, China)
Abstract: GroEL, a 63 kD viral binding protein encoded by groEL gene from endosymbionts in Bemisia tabaci, plays an important role in transmission of plant viruses. A groEL gene from endosymbionts in B. tabaci on cucumber was amplified by PCR method and sequenced. The nucleotide sequence indicated that groEL had 1 668 bp nucleotides and encoded 555 amino acids. This gene had 99.58% similarity on nucleotides level and 99.28% similarity on amino acid level to AF130421, a groEL gene from endosymbionts in B. tabaci in GenBank. There were only 7 variation sites in nucleotides and 4 variation sites in amino acids. SDS-P AGE showed a clear 76 kD fusion protein when the groEL gene was inserted into PinpointTM Xa-1 T vector and expressed in E.coli JM109.
Key words£º endosymbiont; Bemisia tabaci; viral binding protein; prokaryotic expression

The Change of Maize Plant Proteome Affected by Trichoderma harzianum and Pythium ultimum (I)CHEN Jie1,2,Gary G. HARMAN2,Alfio COMIS3,CHENG Gen-wu4,LIU Hai-nan4(1 School of Agriculture & Biology, Shanghai Jiaotong University£¬ Shanghai 201101, China£»2 Department of Horticultural Science, Cornell University, NYSAES, Geneva NY 14456, USA£»
3 Department of Crop & Soil Science, Cornell University, Ithaca NY 14853, USA£»4 College of Plant Protection, Shenyang Agricultural University, Shenyang 110161, China)
Abstract: Trichoderma harzianum strain T22 controls various diseases of maize and other crops, inclu-ding seedling and root rots caused by Pythium ultimum. Seedlings of inbred line Mo17 were grown from T22-treated or untreated seeds in field soil or in field soil intested with the pathogen. Five days after planting, seedlings of Mo17 (5-day-old) were smaller in the presence of P. ultimum and larger in the presence of T22 relative to the control. The combination of T22 with P. ultimum (T22+P. ultimum) resulted in plants as large as T22 alone. Methods for protein extraction and 2-D gel electrophoresis were developed. Proteins in seedlings roots from the various treatments were separated on 2-Dgels and analyzed using PDQuestTM 2-D software. With seedlings produced from T22-treated seeds, there were 104 up-regulated proteins and 164 down-regulated proteins relative to the control, and 97 and 150 from the treatment withT22+P. ultimum, respectively, however, with P. ultimum alone the numbers were much lower than above two treatments. Comparatively, there was very lower similarity of proteome patterns of seedling roots with T22 or P. ultimum or both to control seedlings, the correlative coefficient values were 0.72, 0.51 and 0.49 for the comparisons among control with T22, P. ultimum and T22+P. ultimum, respectively. Moreover, correlative coefficient of proteome patterns between T22 with P. ultimum was only 0.65, and T22 fungal proteome were also not same as any one of seedling roots with various treatments. Taken together, the components in seedling root proteome seemed to be mostly coming from Mo17plants themselves and affected strongly by either microbes, but the effects appeared to be stronger by P. ultimum than by T22. MALDI-TOF analysis of differentially expressed proteins will publish on another paper.
Key words: proteome; corn inbred; Trichoderma harzianum; Pythium ultimum

Cytology of infection process of Fusarium graminearum on wheat spikes
KANG Zhen-sheng1, HUANG Li-li1, H. BUCHENAUER2, HAN Qin-mei1, JIANG Xuan-li1 (1College of Plant Protection£¬ Biotechnology Center, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi 712100, China; 2Institute of Phytomedicine, University of Hohenheim, 70593, Stuttgart, Germany)
Abstract: The infection process of Fusarium graminearum on wheat spikes was examined by scanning and transmission electron microscopy. Macroconidia of the pathogen germinated 6-12 h after inoculation on all parts of spike, and produced one or several germ tubes, which did not infect host tissues immediately, but continued to extend and branch on host surfaces. Hyphal networks were usually formed on inner surfaces of glume, lemma, palea and on ovary 36-48 h after inoculation. However, hyphae grew slowly and no hyphal network was formed on outer surfaces of glume, lemma and rachis. The hyphae on outer surfaces of glume could extend over edges to inner surfaces. Penetration of host tissues occurred on inner surfaces of glume, lemma, palea and on the upper part of ovary by infection hyphae 36 h after inoculation. The hyphae in these infected tissues then spread downward to rachis by inter- and intracellular growth. When the hyphae arrived at rachis 4-5d after inoculation, they extended upward and downward to adjacent florets inter- and intracellularly in vascular bundles and cortical tissue of the rachis. Extension of the pathogen in wheat spike resulted in a series of pathogenic changes in host tissues, such as necrosis and degeneration of host cells, and decolourization and death of whole wheat spike.
Key words£º Triticum aestivum; Wheat head blight; infection process; ultrastructure

Compare of biological activity of kinds of gluco-oligosaccharides and their derivants
QIU Chi1,3, LI Bao-ju1, FAN Hai-yan1,3, SHI Yan-xia1,
NING Jun2 (1 Institute of Vegetable and Flower, CAAS, Beijing 100081, China; 2 Institute of Environment and Ecology, CAS, Beijing 100085, China;3Shenyang Agricultural University, Shenyang 100161, China)
Abstract: Several synthetic glucosyl-oligosaccharides were tested for their biological activities to trigger the defense reactions on soybean cotyledons. The results
indicated that glucohexaose and its derivants had the higher values of EC50 on phytoalexin induction compared to glucoheptaoside and its derivants. Alkylation on the reducing end of these inducers could not eliminate their activities.Dimer of the glucosyl-oligosaccharide showed higher activity than that of its monomer and the activity of salicyl glucoheptaoside was higher than glucoheptaoside.
Key words£º glucosyl-oligosaccharides£» elicitor£» activity£» compare

The change in hydrogen peroxide content and enzyme activity related to adult plant resistance to Rice bacterial blight
SHA Ai-hua, HUANG Jun-bin, LIN Xing-hua, ZHANG Duan-pin
(National Key Laboratory of Crop Genetic Improvement, National Center of Crop Molecular Breeding, Huazhong Agricultural University, Wuhan 430070, China)
Abstract: The concentration of hydrogen peroxide (H2O2)and the activities of peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD) and catalase (CAT) were measured in rice leaves inoculated with Xanthomonas oryzae pv. oryzae T7133 or water at seedling and adult plant stage, respectively. Inoculationwith T7133 on leaves of both seedlings and adult plants resulted in an increase in the concentration of H2O2 and the activities of POD, PPO, and SOD. The concentration of H2O2 and the activities of PPO and SOD were higher in adult plants than in seedlings, whereas the POD activity was lower. The activity of CAT in leaves of both seedlings and adult plants inoculated with T7133 was lower than that in water-treated control, and the adult plants showed much lower activity compared to the seedlings. The results suggest the involvement of H2O2, PPO, SOD, and CAT£¬ but not of POD, in adult plant resistance against rice bacterial blight.
Key words£º Rice (Oryzae sativa); bacterial blight; adult plant resistance; H2O2; enzyme activity

Colonization study of GFP-tagged Bacillus strains on wheat surface
TIAN Tao, QI Xue-chen, WANG Qi, MEI Ru-hong(College of Agronomy and Biotechnology, China Agricultural University, Beijing 100094, China)
Abstract: The green fluorescent protein (GFP) acts as a vital dye upon the absorption of blue light in the living bacterial cell. A gfp gene was inserted into an E.coli-Bacillus shuttle vector to obtain a new vector pGFP4412, in which the gfp gene was expressed under the control of 4412 promoter. Plasmid pGFP4412 was introduced into several Bacillus strains by electroporation and the transformants appeared bright green under blue light. The gfp-labeled Bacillus cereus A-47 was used in the colonization study. The results indicated that the gfp-tagged A-47-gfp could colonize on the surface of wheat and it adhered more tightly to the rhizoplane than to the phylloplane. In the direction from root base to tip, the bacterial distribution showed a clear decreasing tendency in wheat root.
Key words£º Bacillus; green fluorescent protein (GFP); vector; colonization

Expression of Barley yellow dwarf virus-GPV ORF4 in E.coli and preparation of its specific antiserum
LI Yong-li1,2, WU Mao-sen1*, WANG Zhen-yue2, ZHANG Wen-wei1,CHENG Zhuo-min1 (1 Institute of Plant Protection, CAAS, State Key Lab for Biology of Plant Disease and Insect Pests, Beijing 100094£¬ China; 2 College of Plant Protection, Henan Agricultural University, Zhengzhou 450002£¬ China)
Abstract: According to published nucleotide sequence, ORF4 gene of Barley yellow dwarf virus GPV (BYDV-GPV) was synthesized by reverse transcription-polymerase chain reaction (RT-PCR) and inserted into expression vector pET-5a for overexpression in prokaryotic cells. The result of SDS-PAGE showed that specific expression of a 17 kDa protein was achieved after IPTG induction. The expressed protein was purified from SDS-PAGE gel and the antiserum against BYDV-GPV 17 kDa protein was raised in rabbit. The antiserum could be used for specific detection of the 17 kDa protein in oats infected by BYDV-GPV.
Key words£º Barley yellow dwarf virus GPV£» prokaryotic expression£» antiserum

Study on the method of breeding cotton for resistance to Verticillium dahliae JIAN Gui-liang, LU Mei-guang£¨Institute of Plant Protection, CAAS, Beijing 100094, China£©
Abstract: A method that is often used in breeding cotton for resistance to V. dahliae is to select indivi-dual plants under the condition of disease nursery or seriously infected fields.We evaluated the effectiveness of this method in Beijing during 1998-2002.Selection for both resistant and susceptible individuals was conducted in four types of population: (1) F2 plants from resistant ¡Á resistant crosses, (2) F2 plants from resistant ¡Á susceptible crosses, (3) plants from resistant ¡Á tolerant crosses£¬ and (4) plants from resistant variety. The results showed that selection was effective only in the population of type (1) at middle-late growth stages of cotton plants. In resistant or tolerant varieties, no difference was found in resistance between resistant and susceptible plant progeny in later time.
Key words£º cotton; Verticillium wilt; resistant breeding; method

Differentiation ability of monogenic lines to Magnaporthe grisea in indica rice ZHU Xiao-yuan1£¬ YANG Qi-yun1£¬ YANG Jian-yuan1£¬ LEI Cai-lin2£¬ WANG Jiu-lin2, Ling Zhong-zhuan2 £¨1The Plant Protection Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China£» 2Institute of Crop Breeding and Cultivation, China Academy of Agricultural Sciences£¬ Beijing 100081, China£©
Abstract: Pathogenicity of 146 Magnaporthe grisea single spore isolates from indica rice in Guangdong was analyzed against 30 rice blast monogenic lines. Seventeen lines were selected to be the candidates for further construction of differentials. Factor analysis with principal component method of the variance matrix based on the interaction between 17 monogenic lines and 146 blast isolates had been conducted. Nine monogenic lines explaining 80.437% of the total variance were abstracted. According to their contribution to the percentage of variance, they were
listed as follows: IRBLkp-K60(Pi-kp), IRBLi-F5(Pi-i), F128-1(Pi-ta2), IRBL9-W(Pi-9(t)), IRBLsh-S(Pi-sh(1)), IRBLz-Fu(Pi-z), IRBLkh-K3(Pi-kh), IRBL1-CL(Pi-1) and IRBLz5-CA(Pi-z5).Those lines were recommended to be blast monogenic dif-ferentials with which 83 races were identified among the 146 Guangdong isolates and 26 races among 54 isolates from indica rice cultivars in other six provinces. The results showed that 9 selected monogenic lines had good abilities for differentiating the pathogenicity of indica rice blast in South China. Based on the monogenic differentials, cluster and variance analysis method might be applied for the representative isolates selection in the blast resistance evaluation.
Key words£º Magnaporthe grisea Bar.; race; pathogenicity; monogenic lines; near isogenic lines; differentials

Development of a stochastic model simulating spatio-temporal dynamics of plant disease epidemics
LI Bao-hua1, XU Xiang-ming2(1Plant Protection Department, Laiyang Agricultural College, Laiyang, Shandong 265200, China; 2Horticulture Research International, East Malling, West Malling, Kent ME19 6BJ, UK)
Abstract: A two-dimensional stochastic spatial contact model was developed to simulate spatio-temporal dynamics of plant disease epidemics in a pure or mixed cultivation. The model focuses on the interaction of hosts with pathogens and integrates several key underlying processes governing epidemic development, including sporulation, spore dispersal, deposition, infection, incubation, plant growth and di-sease management. The model was programmed with an object-oriented design and coded in C++. Si-mulation results can be outputted either as disease progress curves, a spatial map of disease distributions or as a tabular data list. The model can be used either as a research tool to investigate many aspects of disease epidemics or as a teaching aid to help students to understand the effects of key underlying processes on spatio-temporal dynamics of plant disease epidemics.
Key words£º epidemic£» simulation model£» computer aiding teaching£» simulation study

Effects of Paecilomyces lilacinus M-14 fermentation filtrate on the affinity between soybean cyst nematode and soybean root SUN Man-hong£¬ LIU Xing-zhong(Systematic Mycology & Licheno-logy Laboratory, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China)
Abstract: Effect of fermentation filtrate of Paecilomyces lilacinus M-14 on the attraction of second stage juveniles (J2) of soybean cyst nematode (SCN) to soybean root was tested on agar plate. The filter paper strips soaking up with soybean roots extract or the fermentation filtrate were place on one side of water agar plate and the SCN J2 suspension was inoculated on another side of plate at a 3
cm distance. The results showed that SCN J2 were attracted toward to the soybean root extract and repelled by fermentative filtrate of P. lilacinus M-14 according the distribution rates of SCN J2 on 0-1 cm area nearby filter paper strips. The second stage juveniles were significantly higher in the area treated by the root extract than that by fungal filtrate or mixture of root extract and fungal filtrate (P£¼0.01). The same result was obtained by using soybean roots or the roots dipped with M-14 filtrate (P£¼0.05). There was no significantly difference by placing the treated paper strips or roots at the same time or 24 h before J2 inoculation. It is deduced that P. lilacinus filtrate can obviously reduce the affinity between soybean cyst nematode and soybean roots, and inhibits SCN J2 invasion to soybean root intensively.
Key words£º Paecilomyces lilacinus; fermentation filtrate; soybean cyst nematode; affinity

Identification of AFLP markers linked to Lr38 resistant to Wheat leaf rust JIA Xuan, YAN Wen-xiang, LIU Da-qun* (Department of Plant Pathology£¬ Agricultural University of Hebei, Biological Control Centre of Plant Pathogens and Plant Pests of Hebei Province£¬ Baoding 071001, China)

Sensitive base-line of Blumeria graminis f. sp. tritici to SYP-Z071 and its cross-resistance between triadimefon and SYP-Z071 XIA Ye1,2, ZHOU Yi-lin1, DUAN Xia-yu1, LIU Xue-min2 (1Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, China; 2Northeast Agricultural University, Harbin 150030, China)