Impact Of Host Plant Xylem Fluid On Xylella Fastidiosa Multiplication ...

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(previtellogenic) females peaked in June 2004. The proportion of postvitellogenic females was highest in January 2004, followed by peaks in May and September. The patterns in percentage of previtellogenic, vitellogenic, and postvitellogenic females are similar to those observed in 2002 and 2003. These data suggest that GWSS may have two distinct generations per year. Our observations also indicate that although vitellogenic activity decreases in December, there is not a clear reproductive diapause in the population of GWSS in Riverside, California. The majority of the female GWSS that overwinter are postvitellogenic, suggesting that they have matured and oviposited before entering a reproductive rest period. Histological studies of female oögenesis are being analyzed to verify the data collected from dissections. Morphological observations of the ovarioles are near completion, and the observations reveal that the ovarioles of the ovaries are the telotrophic type with asynchronous ovarioles. Effect of Location on Number of Generations Per Year We initiated sampling of GWSS populations in Tulare and Ventura Counties (California), but were unable to complete this objective due to strong eradication efforts which eliminated populations from our sampling sites. Host Plant Study The preliminary data of our host plant study in the summer of 2002 suggested that there is a potential difference in the female fecundity when caged on different plant species. For this study, adult female and male GWSS were caged on citrus, grape, or oleander, and allowed to mate and oviposit on the plants. We were successful in promoting GWSS oviposition and in rearing GWSS from egg to adult stage on all three host plant types. This experiment is currently being repeated with the late summer, overwintering generation of GWSS in citrus. Although the analysis is not yet complete, it appears that female fecundity patterns are different than those observed in the spring (early-summer) generation of 2002. Scanning Electron Microscopy Studies SEM study of the ovipositor has been carried out since September 2003. The SEM sessions have revealed sensory structures associated with the first, second, and third valvulae of the ovipositor. Many sensory hairs are also found to be located on the pygofer of the female. TEM studies are necessary to determine the exact type of sensillae present on the ovipositor. The external morphology revealed by SEM micrographs suggests that these structures include various types of mechanoreceptors and chemoreceptors. CONCLUSIONS It is too early this season to make any conclusions about host influences on female fecundity, but our prior data have indicated that female fecundity is influenced by host plant type. The observations suggest that it is feasible to target controls towards reproductive hosts (e.g. citrus) of GWSS in order to attempt to control future populations of GWSS. Although it appears that female fecundity varies between host plants, the fecundity may also depend on the generation (e.g. winter, spring, or early summer) being studied. Thus, it is important to avoid limiting year-long GWSS eradication efforts to those populations present on a single host plant type (e.g. citrus). In another experiment, we have successfully reared GWSS on a single host for two successive generations, under greenhouse rearing conditions. These greenhouse data suggest that multiple hosts are not necessary for the survival of GWSS. Thus, GWSS may not need to move between hosts in order to develop and reproduce. However, the pattern may change when GWSS are under field conditions where nutrients may be seasonally limiting. More research on female host selection for oviposition is needed. Now that we have located sensilla that may function as chemoreceptors, it appears likely that there is a chemical basis for GWSS host selection. These sensilla may only function at close range, thus this knowledge may not be useful for trap development. However, the finding of chemosensilla on the ovipositor could be useful for future development of artificial media for GWSS oviposition in colonies maintained for parasitoid rearing. Our study of the oögenesis cycle is defining the timing and number of generations of GWSS in California. This knowledge, combined with an understanding of female host selection, fecundity and offspring sex ratio, will result in a detailed understanding of host plant influences on female development and reproductive success. As indicated by somewhat conflicting results, based on the generation being studied, it is clear that the GWSS has complex reproductive patterns, and may have seasonally changing host preferences. Thus, it is important to modify eradication efforts based on the generation being controlled. We are also beginning to understand the way in which GWSS may sense the environment and may be able to manipulate this system for monitoring trap development. - 161 -
REFERENCES Blua, M. J., Phillips, P. A. and Redak, R. A. 1999. A new sharpshooter threatens both crops and ornamentals. California Agriculture. 53: 22-25. Frazier, N. W. 1965. Proceedings of the International Conference on Virus and Vector on Perennial Hosts, with Special Reference to Vitis. Division of Agricultural Science, University of California, Davis. pp. 91-99. Hopkins, D. L. 1989. Xylella fastidiosa: xylem-limited bacterial pathogen of plants. Annual Review of Phytopathology 27: 271-90. Meadows, R. 2001. Scientists, state aggressively pursue Pierce’s Disease. California Agriculture. 55(4): 8-11. Nielson, M. W. 1968. The leafhopper vectors of phytopathogenic viruses (Homoptera, Cicadellidae) taxonomy, biology, and virus transmission. USDA Technical Bulletin 1382. Purcell, A. H. 1979. Leafhopper vectors of xylem-borne plant pathogens. In. (K.E. Harris and K. Maramorosch, Eds.) Leafhopper Vectors and Plant Disease Agents. Academic Press, New York. pp. 603-625. Purcell, A. H. and Hopkins, D. L. 1996. Fastidious xylem-limiting bacterial plant pathogens. Annual Review of Phytopathology. 34:131-151. Severin, H. P. 1949. Transmission of the virus of Pierce’s Disease of grapevines by leafhoppers. Hilgardia 19: 190. Turner, W. F. and Pollard, H. N. 1959. Life histories and behavior of five insect vectors of phony peach disease. USDA Technical Bulletin 1188. 100 % Previtellogenic % Vitellogenic % Postvitellogenic 90 80 70 Percentage 60 50 40 30 20 10 0 Oct-01 Dec-01 Feb-02 Apr-02 Jun-02 Aug-02 Oct-02 Dec-02 Feb-03 Apr-03 Jun-03 Aug-03 Oct-03 Dec-03 Feb-04 Apr-04 Jun-04 Aug-04 Collection Date Figure 1: Percentage of previtellogenic, vitellogenic, and postvitellogenic adult female H. coagulata per month, according to dissections (October 2001 to September 2004), collected from citrus plants located at the University of California, Riverside, Agricultural Operations. FUNDING AGENCIES Funding for this project was provided by the University of California Pierce’s Disease Grant Program, and by F.G. Zalom and C.Y.S. Peng, Principal Investigators. - 162 -
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IMPACT OF HOST PLANT XYLEM FLUID ON
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0.18 600 Optical density 0.16 0.14
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OPTIMIZING MARKER-ASSISTED SELECTIO
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esistant and susceptible genotypes
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MAP BASED IDENTIFICATION AND POSITI
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esistant genotypes are in process a
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BREEDING PIERCE’S DISEASE RESISTA
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Progeny from crosses of field resis
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a = (1=low, 4= high); b = (1=green,
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v.8) for differences due to the pla
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SHARPSHOOTER FEEDING BEHAVIOR IN RE
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correlated with all other findings
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EFFECTS OF FEEDING SUBSTRATE ON RET
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REFERENCES Bextine, B. and T. Mille
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will also provide insights into the
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OBJECTIVES 1. Determine glassy-wing
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GWSS per 30 s sweep (seasonal avera
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ELISA for the presence of GWSS egg
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Project Leader: Thomas P. Freeman E
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Freeman, T. P., R. A. Leopold, D. R
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pathogen, when they move into viney
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A NOVEL IMMUNOLOGICAL APPROACH FOR
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1.6 GWSS Adults That Fed on Protein
Page 51 and 52: Hagler, J.R. & S.E. Naranjo. 2004.
Page 53 and 54: RESULTS: Oviposition Survey Wild gr
Page 55 and 56: Host specificity testing: No-choice
Page 57 and 58: currently employed morphological ch
Page 59 and 60: increase our present understanding
Page 61 and 62: BIOLOGY AND MORPHOMETRIC ANALYSIS O
Page 63 and 64: Table 1. Mean a developmental durat
Page 65 and 66: EFFECTS OF USING CONSTANT AND CYCLI
Page 67 and 68: REFERENCES Gautam, R. D. 1986. Effe
Page 69 and 70: PARASITISM OF THE GLASSY-WINGED SHA
Page 71 and 72: Table 1. Parasitism by G.ashmeadi o
Page 73 and 74: Project Leader: Robert F. Luck Dept
Page 75 and 76: A more interesting analysis using t
Page 77 and 78: MYCOPATHOGENS AND THEIR EXOTOXINS I
Page 79 and 80: POPULATION DYNAMICS AND INTERACTION
Page 81 and 82: No egg masses were recorded on olea
Page 83 and 84: EXPLORATION FOR FACULTATIVE ENDOSYM
Page 85 and 86: Although Baumannia and Wolbachia we
Page 87 and 88: EFFECTS OF SUBLETHAL DOSES OF IMIDA
Page 89 and 90: Table 2. Mortality and flight perfo
Page 91 and 92: A NOVEL METHOD TO INDUCE OVIPOSITIO
Page 93 and 94: REFERENCES Brodbeck, B. V., P. C. A
Page 95 and 96: Cohorts H. coagulata neonates were
Page 97 and 98: REFERENCES Blua, M. J. and D. J. W.
Page 99 and 100: Figure 2 shows the average numbers
Page 101: REPRODUCTIVE BIOLOGY AND PHYSIOLOGY
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Page 109 and 110: RESULTS Some plant families had no
Page 111 and 112: Table 5. Winter, spring and summer
Page 113 and 114: 16S rDNA is by far the most sequenc
Page 115 and 116: DNA MICROARRAY AND MUTATIONAL ANALY
Page 117 and 118: Inhibition of biofilm is BSA concen
Page 119 and 120: CULTURE-INDEPENDENT ANALYSIS OF END
Page 121 and 122: Borneman, J., M. Chrobak, G. Della
Page 123 and 124: P (CFU P OBJECTIVE 1. Determine the
Page 125 and 126: Purcell, AH and SR Saunders. 1999a.
Page 127 and 128: Figure 1: Southern blot of tolC::ap
Page 129 and 130: Project Leader: David Gilchrist Dep
Page 131 and 132: III. Production of transgenic plant
Page 133 and 134: RESULTS Construction of cDNA Librar
Page 135 and 136: CONCLUSIONS Genetic resistance and
Page 137 and 138: Mutagenesis of Xylella The EZ::TN T
Page 139 and 140: ISOLATION OF BACTERIOPHAGES SPECIFI
Page 141 and 142: Project Leader: Michele M. Igo Sect
Page 143 and 144: outer membrane fractions using two-
Page 145 and 146: 1995; Purcell and Saunders, 1999).
Page 147 and 148: DEVELOPMENT OF SSR MARKERS FOR GENO
Page 149 and 150: Strain Name Host of Origin County o
Page 151 and 152: ROLE OF ATTACHMENT OF XYLELLA FASTI
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wild-type cells was not conclusive
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DETERMINATION OF GENES CONFERRING H
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S1 S2 S3 S4 Nb123456789bb123456789b
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MULTILOCUS SEQUENCE TYPING TO IDENT
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GENOME-WIDE IDENTIFICATION OF RAPID
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Americas and since most of the plan
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EFFECTS OF CHEMICAL MILIEU ON ATTAC
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CONCLUSIONS Our overall objective i
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RESULTS Objective 1. We conducted t
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Redak, R. A., Purcell, A. H., Lopes
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In parallel, an “activating trans
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PATTERNS OF XYLELLA FASTIDIOSA INFE
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% of vessels 100 80 60 40 20 Mugwor
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DOCUMENTATION AND CHARACTERIZATION
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Magnolia002 showed more identity (9
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PLASMID ADDICTION AS A NOVEL APPROA
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GENETIC VARIABILITY OF XYLELLA FAST
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probing activities). In preliminary
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the slow release valve was opened a
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12. Hopkins DL (1977) Diseases caus
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The almost complete absence of info
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QUANTIFYING LANDSCAPE-SCALE MOVEMEN
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Table 1. The mean (±SD) ELISA read
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EPIDEMIOLOGICAL ASSESSMENTS OF PIER
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multiply to relatively high (easily
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SPATIAL DATABASE CREATION AND MAINT
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Project Leader: Thomas M. Perring D
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Figure 2. Individual leaves from a
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The state variables, process functi
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DEVELOPMENT OF A FIELD SAMPLING PLA
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Figure 1. Three main dispersion pat
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OBJECTIVES 1. Track the movement of
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REFERENCES 1. Beard, C.B., Cordon-R
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cases, positive phloem samples were
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EXPLOITING XYLELLA FASTIDIOSA PROTE
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Figure 2. Polymer disk accumulation
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CHARACTERIZATION OF NEONICOTINOIDS
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EVALUATION OF RESISTANCE POTENTIAL
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Project Leader: Doug Cook Dept. of
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Based on the in silico analysis, de
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CONTROL OF PIERCE’S DISEASE THROU
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Figure 1. Oleander ‘White’ afte
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RESULTS During the reporting period
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DEVELOPMENT OF AN ARTIFICIAL DIET A
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DESIGN OF CHIMERIC ANTI-MICROBIAL P
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Neutrophil elastase Cecropin B Chim
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and WTXb is very low (0.00-0.40%) a
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100 100 0.056 North America 100 0.0
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GENETIC DIFFERENTIATION AMONG GEOGR
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Table 1. Single-populations descrip
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MOLECULAR DISTINCTION BETWEEN POPUL
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These novel observations strongly s
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SEQUENCE DIVERGENCE IN TWO MITOCHON
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Table 3. Pairwise sequence distance
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DEVELOPMENT OF MOLECULAR DIAGNOSTIC
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A. B. Relative Density of SCAR Band
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THE ALIMENTARY TRACK OF GLASSY-WING
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We have dissected and identified al
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REALIZED LIFETIME PARASITISM AND TH
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REPRODUCTIVE AND DEVELOPMENTAL BIOL
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Mean adult longevity (days) 25 20 1
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the proposed exploratory work; thes
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SEARCHING FOR AND COLLECTING EGG PA
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REFERENCES Hoddle, M. S. and S. V.
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some Gram(+) bacteria, but are inac
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7. Hultmark, D., et al., Insect Imm
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Isolation of Fungal Pathogens Soil
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IDENTIFICATION OF MECHANISMS MEDIAT
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concentrations of 1.5 x 10 7 bacter
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anchor it in the outer membrane (sh
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SYMBIOTIC CONTROL OF PIERCE’S DIS
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MANAGEMENT OF PIERCE’S DISEASE OF
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pfF mutants are taken up by insects
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Simpson, A. J. G., F. C. Reinach, P
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Al-Wahaibi, A.K., Owen, and J. G. M
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patterns differed among the lines,
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Punja, Z.K. 2001. Genetic engineeri
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mind, we conducted an additional st
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REFERENCES Toscano, N., Byrne, F.,
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RESULTS AND CONCLUSIONS The program
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COMPATIBILITY OF INSECTICIDES WITH
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More tests are in progress to addre
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Impact Of Host Plant Xylem Fluid On Xylella Fastidiosa Multiplication ...

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