Differentials and nomenclature of races of ª«Puccinia striiformisª« West. f.sp
.triticiª«ErikssonWAN An-min(Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, China)

Abstract: China is one of the largest counties where epidemics of wheat stripe rust (Puc cinia striiformis West.f.sp.tritici Eriksson) causes a big problem in wheat production. The disease is a great threat in many wheat-growing areas, e spe-cially when conditions are favorable to the disease epidemics. Studying the p hysiological specialization and monitoring dynamics of races of P. striiformis West. f.sp.ª«triticiª« Eriksson is important to understand the variation of the path ogen and its virulence, effectiveness of resistance genes in disease control , pr ediction of stripe rust epidemics, as well as disease management. Due to the var iation of geographic and regional characteristics, diversity of population struc tures of the pathogen, and so forth, different countries use differential host d ifferentials and nomenclature system of races of ª«P. striiformisª«. China, Unit ed State of America and India have their own differential hosts and nomenclature systems of races respectively. In China, 32 races and more than 30 pathotypes w ere identified by using relatively stable Chinese differentials during 1957-2002 , while in the US 80 races were identified by using US differentials until now. Anot her system of nomenclature of races was put forwarded by Johnson in 1972. In thi s system both world and European differentials were included as integrate differ entials. This system is widely accepted and employed in Europe, Middle Ea st, Asi a, Africa, South Ameri-ca countries, Australia and New Zealand etc. I n considerin g the variability in different countries and regions, additional differentials w ere added into this system by various rust researchers around the world. In addi tion to the long-distance di-spersal of the pathogen spores and disease sp read, t he possible future developments in this area including differential composition, methods of race nomenclature, as well as the international communications among scientists in this research area are also discussed.

Geminiviruses¡ª¡ªan emerging threat for crop produc tion
ZHOU Xue-ping, CUI Xiao-feng,TAO Xiao-rong£¨Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China£©

Abstract: Geminiviruses are a group of plant DNA viruses that occurred worldwide and causesevere diseases in many crop plants. Recombination plays an important role in
viral variation and disease epidemic. In recent years, a novel satellite DNA
mole cule, DNA ¦Â, was found to be associated with monopartite geminiviruses. DNA ¦Â
is required for causing typical symptoms in host plants. In this paper, damage of
geminivirus diseases, viral recombination, discovery of DNA ¦Â and its role in
p at hogenicity, disease complexes composed by geminiviruses and associated small DNA
molecules, and evolutionary relationships among these molecules are discussed
i n detail.

Using uniform design to screen media ingredients for conidia production of barny
ardgrass pathogenic fungi HUANG Shi-wen1, YU Liu-qing1, TANG Qi-yi2, A. K. WATSON3(1 State Key Laboratory of Rice Biology£¬ China National Rice Research In s titute, Hangzhou 310006£¬ China; 2 Zhejiang University, Hangzhou 310029£¬ China; 3 International Rice Research Institute, Manila£¬ Philippines)

Abstract:
Screening media ingredients and corresponding dosage for spore production of fun gi is a basic implementation for biocontrol of weeds. In this study, the optimal
media ingredients and dosage of barnyardgrass (Echinochloa spp.) pathogenic
fungi ª«Curvularia lunataª« and ª«Alternaria alternataª« had been determined by
using uniform design combined with regression analysis. A regression model was
developed. The optimal media ingredients were carrot, celery, parsley, cress,
le ttuce, sucrose and vitamin C for C. lunata, and were carrot, celery, cress,
lettuce and sucrose for ª«A. alternataª«. The regression model was tested with t
he observations of sporulation of ª«C. lunataª« and ª«A. alternataª«. The observ
ed sporulations fi tted well with those calculated with the model. The results confirmed the applic ability of the uniform design for screening media ingredients for spore producti on of fungi.

Cloning and sequence analysis of the coat protein gene of ª«Zucchini yellow mosa
ic virusª«from China GU Qin-sheng1,3, FAN Zai-feng1, Piero Roggero2, CHEN Hong-yun1, Y U Zheng-wang3, LI Huai-fang1* (1Department of Plant Pathology, China Agricultural University, Beijing 1 00094, China; 2Istituto di Fitovirologia Applicata, CNR, Str. delle Cacce 73, 10135 Torino, Italy;3Zhengzhou Institute of Pomology, CAAS, Zhengzhou 450009, China)

Abstract: The coat protein gene of a Chinese isolate (CH-87) of ª«Zucchini yellow
mosaic virusª« was amplified by RT-PCR from total RNA of infected zucchini
leav es and cloned into pUCm-T vector. The coat protein gene of the Chinese isolate con s isted of 837 nucleotides encoding 279 amino acids. Comparison of the nucleotide
sequence of the Chinese isolate with those of 16 isolates from outside the mainl
and of China showed that the coat protein gene of the Chinese isolate formed a n
ew genotype: genotype V as proposed in this paper.

RAPD analysis and group division of ª«Ralstonia solanacearumª« strains in China
CHEN Yong-fang£¬ HE Li-yuan£¬ XU Jin(The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Instit ute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, China)

Abstract: Forty-three representitive strains of ª«R. solanacearumª« collected from 11 Provinces or regions on 6 different plant hosts in China and 4 strains
obtained from other countries were detected by PCR using 15 random primers. Simi
lar DNA fingerprints were obtained by using primers OPB11, OPA15, OPE1 and O PZ10. P otato strains showed identical profiles when primers OPB7, OPA30 and OPF1 were u
sed. High level diversity was found among different strains in the case of usi ng primers OPA14, OPG6, OPG14, OPF5, OPK14, OPK20 and OPK17. Two groups (A, B ) we
re clustered from RAPD data. Group A could be divided into 7 subgroup (A1, A2, A
3, A4, A5, A6, A7), and furthermore A1 involved 2 types (A1-1, A1-2). Group B
co uld be divided into two subgroups (B1, B2) which contained three types (B1-1,
B 1-2, B1-3; B2-1, B2-2, B2-3) respectively. RAPD group A included 27 potato
isola tes from different locations, and they were mainly belonging to race 3 (biovar 2 ). Group B consisted of 20 isolates belonging to races 1 and 5 from different locat
ions and plant hosts. RAPD groups in this study are not relate d to location sources but closely related to hosts.
The geographical origin of R. solanacearum strains in China was preliminaril y an alyzed by PCR. Isolates of potato race 3 were belonging to American division ¡°Americanum¡±ª«, whereas other isolates were belonging to Asian division 2 ¡° Asia-ticum¡±. These results are coincided to RAPD grouping.

Key words£º Ralstonia solanacearumª«; diversity; RAPD; group division; PCR

Effect of ª«Cephalotaxus fortuneiª« on the development of the root-knot
Nematode£¬ Meloidogyne arenariaª« WEN Yan-hua£¬ FENG Zhi-xin(Laboratory of Plant Nematology£¬ South China Agricultural University£¬ Guangz hou 510642£¬ China)

Abstract: Effect of Cephalotaxus fortuneion the development of root-knot nematode£¬ Meloidogyne arenaria was studied in vitro in laboratory and in greenhous e. T he results showed that extraction of twig of ª«C. fortuneiª« could significantly inhibit embryonic development and larva hatching. The pot experiments revealed that powder of dried twig of ª«C. fortuneiª« could prolong the post-embryonic d evelopment and significantly reduce the amount of eggs of female.
Key words£ºCephalotaxus fortunei£»Meloidogyne arenaria£»embryonic development£»
p ost-embryonic development

Detection of whitefly-transmitted geminivirus in ª«Ageratum conyzoidesª« and ª«
Stachytarpheta jamaicensisª« in Hainan, China FAN San-wei, ZHOU Xue -ping
(Institute of Biotechnology, Zhejiang University, Hangzhou 310029£¬ China)

Abstract: Five virus samples collected from ª«Ageratum conyzoidesª« and ª«Stachytarpheta j amaicensisª« in Hainan were detected with triple antibody sandwich ELISA (TA S- ELISA) and PCR, and the results showed that all the virus samples were infec- ted by whitefly-transmitted geminiviruses. Sequence analyses showed two types of vi r uses existed among those samples, and sample Hn2 was mix-infected by two types
o f viruses. This is the first report of whitefly-transmitted geminiviruses in Ha
inan Province.

Key words: whitefly-transmitted geminiviruses£» TAS-ELISA£» PCR

Study on morphology of ª«Ustilaginoidea virensª«
ZHANG Jun-cheng1, CHEN Zhi-yi1, ZHANG Bing-xin2, LIU Yong-feng1, LU Fan1£¨1 Plant Protection Institute, Jiangsu Academy of Agricultural Science, N anjing 210014, China; 2 Department of Plant Protection, Zhejiang Universit y , Hangzhou 310029, China£©

Abstract: Morphology of sexual stroma and different types of propagules of ª«Ustilaginoide a virensª« (Cooke) Takahashi were observed using optical and electronic microsco pes. Perithecia annulosly and monlayer embedded in the rind of stroma. The apex of perithecia grew out of surface of stroma and papillae structure was formed on the surface of stroma. When asci fully developed, the apical wall of perithecia disappeared, and asci emerged from the perithecia. Ascospore was hyaline, unice llular, filiform. Chlamydospore was spherical or elliptical, yellowish-brown to black-brown, with thick and compacted wall. The surface of chlamydospore had m
any verrucae. Both ascospore and chlamydospore formed secondary conidia when the
y germinated. The secondary conidia with similar morphological characteristics as
the submerged conidia obtained from liquid culture, perhaps were thin-wall con
idia. The thin-wall conidia were oval or oblong, 2.6¡«8 ¦Ìm¡Á2¡«5 ¦Ìm, hyaline,
with smooth surface, directly produced next generation of the thin-wall conidi
a
when they germinated. This type of reproduction process could repeat successive ly.

Key words£ºUstilaginoidea virensª«; chlamydospore; ascospore; conidium; stroma; morphological characteristic

The biological characteristics of strain QZ-200 of ª«curvulariaª« sp. for contr
olling ª«Digitaria sanguinalisª«ZHU Yun-zhi£¬ QIANG Sheng(Weed Research Laboratory, Nanjing Agricultural University, Nanjing 210095£¬ Chi na)

Abstract: Factors influencing vegetative growth, conidial germination and sporulation of s train QZ-200 of ª«Curvulariaª« sp., a biological control agent for crabgrass ( Digitaria sanguinalis), had been primarily studied. SCS (soyflour-cornmeal -su-crose) was the best medium for vegetative growth tested so far. The ra nges of temperature and pH for mycelial growth were 10-40¡æ and 2-11, the optimum were 28¡æ and pH 6 respectively; the fungus grew better in Czapek medium with glucos e as carbon source and (NH4)2HPO4 as nitrogen source. The ranges of temperat ure and pH for conidial germination of strain QZ-200 were 10-45¡æ and 2-11, t he optimum were 25-30¡æ and pH 5-8; under RH 100% or in free water, the percen t age of conidial germination was the highest and the germination was stimulated b y adding of peptone, beef extract, TW-80, crabgrass extract or rapeseed oil to the media. The range of temperature for sporulation was 15-35¡æ, the optimum wa s 28¡æ; the continuous illumination gave better result than an alternating o f light and darkness for 12 hours, and the black fluorescent light was the best illumin ation for sporulation.

Key words£º strain QZ-200; bioherbicide; Digitaria sanguinalis; biological
characterist ics

DNA polymorphism of root-knot nematodes in South China revealed by RAPD
JIANG Han1£¬ LIAO Jin-ling1£¬ HU Xian-qi2, WANG Xin-rong1, FENG Z hi-xin1
(1Laboratory of Plant Nematology,South China Agricultural University, Guan
gzhou 510642, China; 2Key Laboratory of Plant Pathology, Yunnan Agricultur
al University, Kunming 650201, China)

Abstract: Among 48 random primers selected for detecting the genetic polymorphism of genom ic DNA of 30 populations, 12 arbitrarily primers were suitable for RAPD analysis . With the 12 primers,179 polymorphic bands were obtained. There were no RAPD band s sharing by all the 30 populations, which revealed the abundant diversity among
the tested species.The diversity level among the species was greater than that
within the species. All these results indicated that the 12 primers are suitable
for detecting the genetic diversity and relationship among these populations.
ª«Meloidogyne haplaª« appeared in a most distant group from the other three (M
. arenaria, M.javanica and M.incognita). Among the three major ª«Meloidogy neª«species, ª«M.javanica and M.incognitaª«was seen to be the more closely related.The cluster analysis based on the RAPD bands showed that different spec ies clustered in low D value,but different populations in the same species in hi gher D value. The result was almost consistant with what revealed by the morphol ogical studies and other DNA analysis. It indicated that RAPD analysis is ration al and feasible for identificating and genetic diversity analysising of root-kn o t nematodes. The possibility for the identification ª«M.incognitaª« races by RAP D was discussed.

Key words£º Meloidogyneª«£» polymorphism; RAPD£» DNA

Induced-resistance of cucumber by nitrogen containing heterocycles to powdery m
ildew (ª«Spaerotheca fuligineaª«)CHEN Xi-wen1, HAO You-jin1, CHEN De-fu1, ZHANG Wen-qin2(1College of Life Sciences, Nankai University, Tianjin 300071, China£»
2Department of Chemistry, Tianjin University, Tianjin 300072, China)

Abstract: The induced-resistance of cucumber to powdery mildew (ª«Spaerotheca fuligineaª« ) by eleven nitrogen containing he-terocycle compounds was investigated. Bi oassay in the greenhouse revealed that the tested compounds had different induction ac tivities, among which (E)-4-£Û2-(4-biphenyl) ethenyl£Ý pyridine (BEPy) and O
, O'-1,4-butanediyl-4,4'-bis £Û(E)-2-(4-oxyphenyl) ethenyl£Ý pyridine (DPyE
POB) had s ignificant activities to tiger resistance. The disease index of cucumbers treate d with BEPy and DPyEPOB were 31.4 and 40.4 on the sixth day, i.e. 40.1% and 23.1 % of the control, respe-ctively, and their disease index on the tenth day w
ere 34.8 and 42.2, i.e. 38.7% and 25.7% of the control, respectively. The resist
ance- inducing activity of BEPy decreased 60 h after treatment, whereas that of DPyEPO
B could keep in a high level during the whole test period. Compared with salicyl
ic acid (SA), a well-known systemic acquired resistance inducer, BEPy showed a
similar resistance-inducing activity, while DPyEPOB was weaker. The activities
of peroxidase (POD), phenylalanine ammonialyase (PAL) and polyphenoloxidase (PPO
), which were involved in plant resistance, were also assayed. The results showe
d that BEPy enhanced the activities of POD£¬PAL, and PPO by 2.55, 1.45 and 8.83
times 60 hours after treatment, respectively, followed by a decline of the activ
ities of POD and PAL to the control level 144 hours after treatment. The PPO act
ivity kept high than the control during the whole test period. The activity curv es of these enzymes were similar to that obtained with SA-treatment, but varied in the hoisting range and lasting period. The relationship between three enzymes
and the induced resistance of cucumber to powdery mildew is also discussed.

Key words£º nitrogen containing heterocycles£» induced-resistance£» cucumber£» ª«Spaerothec a fuliginea£»enzyme activities

Isolation and purification of Pf-toxin from ª«Pestalotia funereaª«
ZHU Tian-hui1£¬ YE Hua-zhi2£¬ LUO Meng-jun2 (1College of Forestry and Horticulture£¬Sichuan Agricultural University, Y aan 625014, China£» 2Provincial Key Laboratory of Forest Protection, Sichu an Agricultural University,Yaan 625014, China)

Abstract: Culture filter of ª«Pestalotia funereaª« was primarily fractioned by enth
anol precipitation. High molecular weight substances, such as the proteins, were
shown to be nonpathogenic to the cut-root seedling of ª«Pinus massonianaª« and
P. e lliottiª«by soaking method, whereas the non-protein part was pathogenic. Nine
fractions separated by gel H60 column chromatography using n-butanol¡Ãmethanol¡Ã
w at er (4¡Ã1¡Ã2) as mobile phase were assayed. Among them, three fractions with Rf v alues of 0.83£¬ 0.79£¬ 0.80 were found to be pathogenic to the leaves of ª«P. m
assonianaª« and ª«P. elliottiª«.
Key words: ª«Pestalotia funereaª«; pine; bio-determination; toxin; purification

Influence of cucumber powdery mildew (ª«Sphaerotheca fuligineaª«) infection on p
hotosynthetic electron transport and protein D1 expression of cucumber (ª«Cucumi
s sativusª« L.) leafSHEN Xi£¬ LI Hong-yu*, WEN Ya, MENG Xue-qin, ZHOU Gong-ke, ZHANG Li-xin, LIANG Hou-guo(Department of Biochemistry and Molecular Biology, School of Life Science, Lanzh ou University, Lanzhou, Gansu 730000, China)

Abstract: The changes in chlorophyll contents, photosynthetic electron transport rate and expression level of photosynthetic center protein D1 were studied in thylakoid o f cucumber leaves after the infection of powdery mildew. Chlorophyll contents,es pecially Chl b,significantly decreased than Chl a after the infection. The elect ron transport rate of photosynthetic chain was greatly inhibited by the pathogen , the inhibition, however, was mainly attributed to the inhibition of PS
II. The D1 protein expression showed similar trend to that of PS II electron transport rates, indicating that suppression of D1 protein i s a possible cause for the inhibition of PS II electron transport
.
Key words£º cucumber£» powdery mildew£» thylakoid membrane£» protein D1

A 30 successive years' observation on the performance of several wheat culti
Vars in resistance to stripe rust£¨ª«Puccinia striiformisª« West.£© in the southern
region of Gansu Province of ChinaZHOU Xiang-chun1£¬ DU Jiu-yuan2£¬ YANG Jun-hai1
(1 Lanzou Agricultural School, Lanzhou, Gansu 730020£¬ China£» 2 Tia nshui Agricultural School, Qingshui, Gansu 741400, China)

Abstract: Observation was conducted on the performance in resistance to stripe rust of sev en wheat cultivars during the period 1973-2002 in the southern region of Gansu
P rovince, where the environment is conducive to the disease and new races of the
fungus were detected very frequently. These wheat cultivars were and/or are stil
l being grown commercially, with the acreage of more than 6 000 hm2 per year,
i n the southern region of Gansu Province. The cultivars were assessed on their re
sponse to the disease in field plots by artificial inoculation with the stripe r
ust fungus race which were predominant in the year when the test was conducted.
The general finding is that the resistance remains effective for a period much
longer in some cultivars than that in the others. The two wheat cultivars Libell
ula and N.Strampelli showed the longest duration in effectiveness of resistance
to the disease, with disease indexes not higher than 5%, from 1974 to 2002 when
the commercially planting acreage of Libellula was more than 6 000 hm2 per yea
r at the early years and it reached 34 000 hm2 per year later. The cultivar La
ntian 12 h as showed stable performance in resistance with disease indexes not higher than 4% since 1991. The other four cultivars were highly resistance to the disease in the first several years when they were commercially used and they became suscep
tible later. The paper discussed some characteristics of these cultivars in rela
tion to their resistance to the disease. Particularly, the resistance of L
ibellula expresses in a quantitative manner.

Key words£º wheat£» stripe rust£» cultivars£» durable resistance

Isolation of HT-toxin from ª«Exserohilum turcicumª« with HPLC and activity moni
toring of its seven purified fractions
LIU Yun-hui1, ZHANG Li-hui2, DONG Jin-gao1, WU Guo-jiang 1(1 College of Life Science£¬ Hebei Agricultural University, Baoding 071001 , China; 2 College of Plant Protection, Hebei Agricultural University, Bao ding 071001, China)

Effect of two bacteria strains on the survival and reproduction of ª«Bursaphelen
chus xylophilusª«TAN Jia-jin1, FENG Zhi-xin2 (1College of Forest Resources and
Environment, Nanjing Forestry University, Nanjing 210037, China; 2 Lab of
Plant Nematology, South China Agricultural University, Guangzhou 510642, China

Cloning and sequence analysis of elicitin genes from ª«Phytophthora boehmeriae
SHEN Gui£¬ WANG Yuan-chao£¬ ZHENG Xiao-bo (Key Lab of Monitoring and Management of Plant Diseases and Insects of Chinese Ministry of Agriculture, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China)

The cloning and sequences analysis of CP gene of Yunnan isolates of ª«Lily sympt
omless virusª«WANG Ji-hua1, DING Yan-ming2, WANG Li-hua1
(1 Yunnan Academy of Agricultural Sciences, Supervision and Testing Centre
for Flower, China Ministry of Agriculture, Kunming 650205, China; 2 Y
unnan Entry-Exit Inspection & Quarantine Bureau, Kunming 650228£¬ China)