Abstract: Peanut virus diseases are economically important to peanut production. In recent10 years, great progress has been made in researches on molecular biology of Peanut stunt virus(PSV),Peanut stripe virus物(PStV) and 物Tospovirusesinfecting peanut, which made better understanding of the genomeㄛgenetic diversity, evolu tion and determination of species, subgroup and strain of the viruses. Following molecular characterization of two subgroups of PSV, a third subgroup was establ ished from PSV Chinese strains based on serology and sequence analysis of RNA3. It was demonstrated that PStV strains with symptom diversity were evolved indepe ndently in China and some Southeast Asian countries based on comparison of sequence homology of coat protein gene. The progress in molecular biology of 物Tospovirus物 has increased the viruses from 物Tomato spotted wilt virus物 (TSWV) alone to 13 species in past 10 years, among which 5 species infect peanut.
Key wordsㄩ viruses infecting peanut; 物Peanut stunt virus˙ Peanut stripe virus; Tospoviruses物; molecular biology
Identification of Watermelon mosaic virus 2 pumpkin isolate and its coat pro
tein gene sequence YANG Guo-hui1ㄛ2ㄛ ZHANG Zhong-kai1*ㄛ CUI Chong-shi2
(1Yunnan Key Lab of Agro-Biotechnology, Kunming 650223ㄛ China˙ 2Horticultural
College of North-East Agricultural University, Haerbin 150030ㄛ China)
Abstract: Watermelon mosaic virus物 2 (WMV-2) was detected in infected pumpkin
plant collected from Heilongjiang (HLJ) Province by electron microscopy and
enzyme-linked immunosorbent assay (ELISA). A specific fragment about 850 bp
in length covering coat protein(CP) gene region was amplified by reverse transcription
polymerase chain reaction (RT-PCR) and immuno capture PCR (IC-PCR). The PCR
product was cloned into pGEM-T vector. Sequences analysis showed that CP gene
of WMV-2 i solate HLJ had 852 nucleotides in length, encoding 284 amino acids
with molecula r weights of 31.8 kDa. Comparison showed it shared 92.2%-94.0%
nucleotide acid
identities and 94.5%-98.1% amino acid identities with the published sequencesㄛ
respectively. When compared with the two reported Chinese isolates,WMV-2-HLJ
CP shared 98.5% or 91.5% nucleotide sequence identity and 98.5% or 95.0% amino
aci d sequence identity with that of WMV-2 Shanxi isolate or Zhengzhou isolate.
Key wordsㄩ pumpkin; WMV-2; identification; CP gene
Rapid detection of citrus bacterial canker disease (Xanthomonas axonopodis pv. citri物) with polymerase chain reaction (PCR)WANG Zhong-kang1, SUN Xian-yun2, XIA Yu-xian1,ZHOU Chang-yong3, YIN You-ping1(1Research Center of Genetic Engineering, Key Lab for Biomechanics & Tissue Engineering under the State Ministry of Education, Chongqing University, Chongqing 400030, China; 2College of Plant Protection, Southwest Agricultural University, Chongqing 400716, China˙ 3Citrus Research Institute, ChineseAgriculture Science Academe, Chongqing 400712ㄛ China)
Abstract: Citrus bacterial canker disease (Xanthomonas axonopodis pv. citri) is now still on the list of quarantine pest of international and Chinese administra tion. One pair of specific primers (JYF5/JYR5) designed from published sequence based on encoding a conserved hypothetical protein gene in genome of Xac (Nature , 2002) was screened and developed for specifically detecting different pathovar s of Xac and citrus leaves and fruit with suspicious symptom of CBCD as well as healthy leaves of citrus spiked with pathogen of Xac. The specification of primer pair is better than the previous ones designed from plasmid DNA or from 16 S rDN Asequences of Xac. PCR amplification product of 413 bp target band was generated from target pathogen but not from non-pathogenic xanthomonads of citrus epiphy tes and several plant pathogenic bacteria as well as from soaking solution of hea lthy citrus tissue. Limit of detection was 10 cells or 1.56 pg per micro liter p er reaction. Stabilized results were obtained using different type of thermocycl ers with corresponding PCR profiles. The accurate and rapid molecular diagnosis technique was applied in the eradication program and for epidemiological purposes in maintenance and protection of non-quarantine area of citrus production was established. It is easy to use and will promote standardization of reaction proc ess based on detection kit of PCR with pre-coated solidly reagents and simplifi ed sample preparation procedure.
Key wordsㄩ Xanthomonas axonopodis物pv. citri; citrus bacterial canker disease; PCR˙quarantine
Cytopathological changes of maize leaf tissue infected by Curvularia lunata物 (Wakker) Boed. HUANG Li-li, WANG Lan, KANG Zhen-sheng*ㄛ ZHAO Jieㄛ ZHANG Guan-qu (1College of Plant Protection, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi 712100, China˙ 2Plant Sci-Tech College, Tarim Reclamation University of Agriculture, Alar, Xinjiang 843300, China)
Abstract: The transmission electron microscope and cytochemical technique were
employed toexamine the alteration of ultrastructure and cell wall components
of maize leaf tissue, uninfected and infected by Curvularia lunata物(Wakker)
Boed. After invading into the maize leaf tissue, the pathogen spread intercellula
rly and then formed intracellular hyphae in the necrotic host cells. As the
extension of the hyphae, a series of cytopathological changes occurred in the
host tissue, including plasmolysis, necrosis of protoplasm, degeneration of
organelles such as chloroplasts and vacuoles, and collapse of host cells. The
cytochemical label ing of main cell wall components in 物C. lunata物-infected
leaf tissue showed that the labeling densities for cellulose, xylan, pectin
were significantly reduced as compared with that in unino-culated healthy tissue.
These results indicatethat cell wall-degrading enzymes such as cellulases, xylanases,
pectinases se creted byC. lunata物 are closely related to the penetration and
extension of pat hogen.
Key wordsㄩ maize; Curvularia lunata; ultrastructure; cytochemistry; cell wall-degrading enzymes
The dynamic effects of Colletotrichum capsici f. nicotianae物toxin on MDA content and some protective enzymes in tobacco FANG Bao-hai, ZHANG Guang-min, CHI Chang-feng, LIU Ping(College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China)
Abstract: The dynamic changes of malondialdehyde (MDA) content and superoxide dismutase (SOD),peroxidase ㄗPODㄘ and polyphenol oxidase ㄗPPOㄘ activities induced by Colletotrichum capsici物 f. 物nicotianae物 toxin on tobacco were studied.The activities of SOD,POD and PPO in both resistant cultivarㄗBurley21ㄘ and suscep tible cultivarㄗNC82ㄘincreased in the early stage after treatment,and decreased in the late period.However,the resistant cultivar Burley21 showed a higher leve l of SOD, POD and PPO activities and a lower changing rate of MDA content than t hose in the susceptible cultivar NC82.Moreover,the activities of three tested enz ymes in Burley21 also declined more slowly in the late time after inoculation.It demonstrated that Burley21 possessed stronger protective potential and was mor e resistant to membrane lipid peroxidation.
Key wordsㄩ Tobacco black death disease; Colletotrichum capsici f. nicotianae物; toxin; MDA; SOD; POD˙ PPO
Effects of 物Potato virus Y物 infection on chloroplast ultrastructure, photosynt
hesis and chlorophyll fluorescence quenching in potato leavesPENG Yan-huiㄛ LEI
Juan-li, HUANG Li-fengㄛ YU Jing-quan(College of Agriculture and Biotechnology,
Zhejiang University, Hangzhou 310029, China)
Abstract: The effects of 物Potato virus Y物 (PVY) infection on chloroplast ultrastructure and photosynthesis were investigated in potato. Electron microscopy showed that PVY infection disrupted the development of chloroplast and cell structure, resulted in the decreased size and irregular shape of chloroplast and starch particles. As the disease progressed, chlorophyll content, electron transfer rate and net photosynthetic rate significantly decreased. The maximal photochemical efficiency, however, was not influenced by viral infection. It seems likely that the disrupted chloroplast together with the inactivation of enzymes in Calvin cycle are responsible for the suppressed photosynthesis by PVY.
Key wordsㄩ Potato virus Y物; potato˙ ultrastructure; net photosynthesis rate; stereology; chlorophyll fluorescence
Study on seed transmission of 物Sugarcane mosaic virus物 in maize LI Liㄛ WANG
Xi-fengㄛ HAO Hong-jingㄛ ZHOU Guang-he (Institute of Plant Protection, Chinese
Academy of Agricultural Sciences, Beijing 100094, China)
Abstract: Sugarcane mosaic virus物 (SCMV) is an important seed-borne virus in
maize. This paper is report on the detection of SCMV in maize seed (inbred Mo17)
by ELISA, electron microscopy, biological assay and tissue culture technology.
The
SCMV particles or inclusions were found in testa, aleuronic layer of endosperm
a
nd embryo tissue, but not in starch layer of endosperm. The virus particles
in a
leuronic layer and embryo have been shown to invade the growing maize seedling.
Key wordsㄩ Sugarcane mosaic virus物; embryo carrying virus; seed-borne; infected
Purification and characteristics of a harpin-like protein from 物Xanthomonas
or
yzae物 pv. 物oryzicola物LU Xu-zhongㄛ SHAO Minㄛ WEN Wei-gangㄛ WANG Jin-sheng
(The Key Laboratory of Mo-nitoring and Management of Plant Diseases and Insects
of Chinese Ministry of Agriculture, Department of Plant Protection, Nanjing
Agri
cultural University, Nanjing 210095, China)
Abstract: A proteinaceous elicitor which could induce hypersensitive response
(HR) reaction on tobacco was purified by (NH4)2SO4 precipitation, ultra speed
centrif
ugation, preparative IEF and ion exchange techniques from cells of strain M51,
an hrp- mutant of the wild type RS105 (物Xanthomonas oryzae物 pv. 物oryzicolaㄛ
Xoo
c物). The molecular weight of this protein was 25.5 kDa determined by 15% SDS-PAG
E. It possessed many similarities with HarpinEa (from 物Erwinia amylovora
) and HarpinXoo (from 物Xanthomonas oryzae物 pv. 物oryzaeㄛ Xo物) in physical and
biological properties. This protein was heat-stable and sensitive to protease
K. It also could elicit a typical HR reaction on tobacco leaves, which was dispelled
by eukaryotic metabolic inhibitors: actinomycin D, cycloheximide and LaCl3.
We also found that the protein had the ability to induce disease-resistance
to TMV when sprayed on tobacco. Thus, the protein is de-signated as HLPXooc
(Harpin-like protein).
Key wordsㄩ Xanthomonas oryzae物 pv. 物oryzicola (Xooc)˙物 hypersensitive response (HR)˙proteinaceous elicitor˙ Harpin induced resistance
Effects of 物Meloidogyne incognita物 on the growth and intrinsic hormones of
gin
gerGUO Yan-yin, WANG Xiu-feng, XU Kun, ZHU Yan-hong, ZHENG Yong-qiang(College
of Horticulture, Shandong Agricultural University, Taian 271018, China)
Abstract: When ginger plant was infected by 物M.incognita物, the root was damaged
first, and the height, fresh weight of above-ground part, fresh weight of root
and rhizome weight were decreased significant, yield was decreased 47.96%. Results
also indicated that content of GA, IAA and ZR in ginger leaves infected by 物M.i
ncognita物 all were decreased significantly, while that of ABA was decreased
in
early growth stage and was increased in later growth stage. The ratio of GA
and ABA
was decrease dramatically, growth of ginger was influenced seriously, more
yellow leaves and early plant decrepit. Content of GA, IAA, ZR and ABA in rhizome
were changed like that in ginger leaves, but content of ZR and IAA were increased
dramatically in September, this was related to the development of giant cell
afte
r root-knot nematode infected rhizome and set up infected base because giant
ce
ll could cause rhizome split. At later growth stage, 物M.incognita物 increased
GA
/ABA and content of GA, so promoted transportation of nutrients to root part
and led to the compensation growth of roots; but decrease of IAA and ZR were
unfavo
rable for 物M.incognita物 setting up infected site, so too much root knot couldn
't be developed in roots.
Key wordsㄩ ginger; 物Meloidogyne incognita物; intrinsic hormones; growth
Effect of Toxin Extract from Alternaria alternata(Fr.) Keissler on Leaf Photosynthesis
ofEupatorium adenophorum物 SprengDAI Xin-bin2,CHEN Shi-guo2,QIANG Sheng1*,AN
Chuan-fu1,ZHANG Rong-xian2(1 Weed Research Laboratory, Nanjing Agricultural
University, Nanjing 210095, China;2 Photosynthetic Research Laboratory, Nanjing
Agricultural University, Nanjing 210095, China)
Abstract: The relationship between the pathogenicity of a new toxin extract
from Alternaria alternata物 (Fr.) Keissler infecting crofton weed (物Eupatorium
adenophorum Spreng) that is one of the most troublesome invasive weeds and its
inhibitionon photosynthesis was studied. The results showed that the toxin extract
greatly inhibited oxygen evolution rate and appearance quanta efficiency declined
evidently before any distinct change in leaf appearance was observed. The main
action
site of toxin in chloroplast was on thylakoid membrane. It inhibited electron
t
ransfer reaction of two photosystems. The toxin did not affect prominently photo
synthetic pigment content and RuBP carboxylase level and activity.
Key words: Alternaria alternata; Eupatorium adenophorum;phytotoxin; photosynthesis
Life and reproductivity tables of 物Magnaporthe grisea物 in CO39 near-isogenic
rice linesZHANG Wei-min1, WANG Zhen-zhong1, CAI Yin-jie2, JIA Xian-lu1 (1College
of Natural Resources and Environment, South China Agricultural University, Guangzhou
510642; 2Nantong Agriculture Vocation Technical College, Nantong, Jiangsu 226007)
Abstract: The near-isogenic lines (NILs) of rice with CO39 genetic background
and three major physiological races (ZC13, ZB1 and ZB5) of rice blast fungus,
物M
agnaporthe grisea物, occurring in Guangdong Province were used to establish the
cohort life and reproductivity tables on twelve race℅line combinations showing
compatible and incompatible reactions. Survival and reproduction of the pathogen,
aswell as their effects on disease development were studied for the compatible
co
mbinations. The function of resistant genes against pathogen infection was also
studied for the incompatible combinations. The result indicated that in compatib
le and incompatible combinations, each step from pathogen vegetative growth
to r
eproduction may more or less involve susceptibility/resistance expressions of
th
e host. In CO39 NILs, no difference in spore germination and hyphae growth rate
among the tested spores of the same races was found. However, those among spores
between the races were significantly different. The critical time points of
exp
ression of compatible or incompatible reaction were at the beginning of coloniza
tion and reproduction of the pathogen. Lower colonization rate and slower lesion
formation related to expression of more resistance of the host. Among those
in
reproductivity table relating to population dyna-mics, four parameters, av
erage sporulation per lesion per generation (F'), net reproduction rate (R0),
maximu
m relative growth rate (rmax) and index of population trend (I), were more
applicable to reflect the relationship between the reproductive status of 物M.
grisea 物and expression of susceptibility/resistance of the host.
Key wordsㄩ Magnaporthe grisea物˙ near-isogenic rice lines˙ life table˙ reproductivity table
Induced resistance to 物Cladosporium cucumerinum物 in cucumber by pectinases
ext
ract of 物Penicillium oxalicum物PENG Xia-wei, ZHANG Hong-xunㄛ BAI Zhi-huiㄗResearch
Center for Eco-Environmental Sciences, Chinese Academy of Sciences,
Beijing 100085, Chinaㄘ
Abstract: The induced resistance to 物C. cucumerinum物 in etiolated cucumber
see
dlings was elicited by crude pectinases extract (PE) from the solid-state ferme
ntation with 物P. oxalicum物 BZ-2002. Etiolated cucumber seedlings of 4 susceptible
cultivars inoculated with 物C. cucumerinum物 at 48 h after sprayin
g treatment with PE exhibited different degrees of increased resistance to the
d
isease. Cucumber seedlings of cv. Zhongnong No.5 expressed the highest resistanc
e with inducing efficiency of 62.51%. Different concentrations ranging from
20
to 300 U/mL of crude PE were tested for their effect on induced resistance to
cuc
umber scab. The results indicated that the plants treated with PE at the concent
ration of 20 U/mL resulted in a little higher disease index than control plants,
induced resistance of the plants was enhanced at the PE concentrations between
40 U/mL and 200 U/mL. Spraying cucumber seedlings with PE 12-72 h before inocul
tion provided significant control of the disease compared with control and the
reduction rates of disease index were 29.64%-60.02 %. No protection was observe
d in seedlings treated with PE 0-6 h before inoculation or 0-48 h after inocul
ation. With the increase of inoculum, the efficiency of induced resistance cause
d by PE was reduced. No inhibitory activity was observed on conidial germination
and germ-tube growth of 物C. cucumerinum物 at various concentrations of PE (20
-200 U/mL). On the contrary, they had stimulative effect on conidial germinatio
n and germ-tube growth.
Key wordsㄩ Penicillium oxalicum物˙ pectinase˙ 物Cladosporium cucumerinum物˙ cucumber˙induced resistance
Digoxigenin-labelled cDNA probes for the detection of 物Tobacco mosaic virus,
Cucumber mosaic virus物 and 物Potato virus Y物DU Guo-yingㄛ WANG Xi-fengㄛ ZHOU Guang-he(State
Key Laboratory for the Biology of Plant Diseases and Pests, Institu te of Plant
Protection, Chinese Academy of Agricultural Sciences, Beijing 100094,
China)
Abstract:The coat protein genes of 物Tobacco mosaic virus, Cucumber mosaic virus
and 物Potato virus Y物 were amplified from the extracted RNA of infected tobacco
leaves by RT-PCR, using the specific primers designed according to the nucleotide
sequences of the coat protein gene of the three viruses. These three fragments
wer
e cloned into pGEM-T easy vectors respectively, and then the nucleotide sequen
ces were determined, their lengths were 442狐776 and 808 bases respectively.
Usi
ng these clones, digoxigenin-labelled cDNA probes were synthesized by PCR, and
applied in dot-blot hybridization to detect TMV, CMV and PVY. The sensitivity
f
or detection of the total RNA of infected tobacco leaves by TMV, CMV and PVY
was
1￣1 000, 1￣10 000, 1￣320 respectively; while that using simple extraction of
infected leaves was 1￣100, 1￣100 and 1￣10 respectively. The result showed t
hat the three probes were stable, sensitive and specific.
Key wordsㄩ TMV; CMV; PVY; digoxigenin-labelled cDNA probe; dot-blot hybridization
Identification and characterization of biocontrol bacterial strain 2P24 and
CPF-10
WEI Hai-lei, WANG Ye, ZHANG Li-qun*, TANG Wen-hua(Department of Plant Pathology,
China Agricultural University, Beijing 100094, China)
Abstract:Bacterial strains 2P24 and CPF-10 are two biocontrol agents isolated from wheat rhizosphere in Shandong Province. These two strains were classified into the genus of 物Pseudomonas物 by analyzing the 16S rDNA sequence. Further detection of physiological and biochemical characteristics revealed that both strains belonged to 物P. fluorescens物. The strain 2P24 fell into biovar ｉ and CPF-10 fell into biovar V. Both 2P24 and CPF-10 produced several antifungal compounds, such as antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG), hydrogen cyanide (HCN), siderophore(s) and extracellular proteinase, and showed inhibitory to 物Rastonia solanacearum, Fusarium oxysporum and Rhizoctonia solani in the dual-culture test in plates. In greenhouse, strain 2P24and CPF-10 showed 63.0% and 62.4 % efficiency to control tomato bacterial wilt, respectively.
Key wordsㄩ biocontrol; 16S rDNA; 物Pseudomonas fluorescens物; biocontrol factors; Tomato bacterial wilt
The comparative biology of pathogens of root rust rot of ginseng and American
ginseng YAN Xue-rui, FU Jun-fan (College of Plant Protection, Shenyang Agricultural
University, Shenyangㄛ Liaoning 110161, China)
Investigation on the over-summering of 物Puccinia striiformis物 f.sp. 物tritici
in the north-western mountain area of Hubei Province of ChinaWAN An-min1, ZHANG
Zhong-jun2*, JIN She-lin3, YU Da-zhao4, ZHAO Zhong-hua5, SHI Shang-bai6
(1 Plant Protection Institute, Chinese Academy of Agricultural Sciences, Beijing
100094, China; 2 Plant Pathology Department, China Agricultural University,
Beijing 100094, China; 3 Plant Protection Institute, Gansu Academy of Agricultural
Sciences, Lanzhou 730070, China;4 Plant Protection and Soil Science Institute,
Hubei Academy of Agricultural Sciences, Wuhan 430064, China; 5 National Agro-Technical
Extension and Service Center, Ministry of Agriculture of P. R. China, Beijing
100026; 6 Plant Protection Station of Hubei Province, Wuhan 430070, China)
New record of Ceratocystis wilt on pomegranate in Yunnan HUANG Qiong1ㄛ LU Wen-jie1ㄛ
FAN Jin-xiang2ㄛ LU Jin3ㄛ ZHU Wen-di3ㄛ GAO Xiang-yun4ㄛ CHEN Hai-ru1ㄛ ZHU You-yong1
ㄗ1 Key Laboratory of Plant Pathology, Yunnan Agricultural University, Kunming
650201, China˙ 2 Plant Protection and Quarantine Station of Honghe Prefecture,
Mengzi 654300, China˙ 3 Plant Protection and Quarantine Station of Mengzi County,
Mengzi 654300, China˙ 4 Science and Technology Office of Mengzi County, Mengzi
654300, Chinaㄘ