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81.
82.
Takako Ishiga Yasuhiro Ishiga Shigeyuki Betsuyaku Nobuhiko Nomura 《Journal of General Plant Pathology》2018,84(3):189-201
Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), which causes bacterial speck disease of tomato, has been used as a model pathogen to investigate the molecular basis of plant–pathogen interactions. The function of many potential virulence factors encoded in the Pst DC3000 genome and their modes of action are not fully understood. P. syringae is known to produce the exopolysaccharide alginate. Although AlgU, a sigma factor, is known to regulate the expression of genes such as algD related to alginate biosynthesis, the molecular mechanisms of AlgU in the virulence of Pst DC3000 is still unclear. To investigate the function of AlgU and alginate in plant–bacterial pathogen interactions, we generated ΔalgU and ΔalgD mutants. After inoculation with ΔalgU but not ΔalgD, host plants of Pst DC3000 including tomato and Arabidopsis had milder disease symptoms and reduced bacterial populations. Expression profiles of Pst DC3000 genes revealed that AlgU can regulate not only the expression of genes encoding alginate biosynthesis, but also the expression of genes related to type III effectors and the phytotoxin coronatine (COR). We also demonstrated that the ΔalgU mutant showed full virulence in the Arabidopsis fls2 efr1 double mutant, which is compromised in the recognition of PAMPs. Further, the application of COR was able to restore the phenotype of the ΔalgU mutant in the stomatal response. These results suggest that AlgU has an important role in the virulence of Pst DC3000 by regulating COR production. 相似文献
83.
Metarhizium guizhouense PSUM02 treated males of Bactrocera latifrons were investigated for the mating competition among males and mating choice by female flies to develop an auto-dissemination for the control of B. latifrons. In the present study, on day 1–4 of experiment, M. guizhouense–treated male flies were equally competitive with the normal male flies as we did not observe any differences in mating by treated and normal male flies of B. latifrons. Further, mating competitiveness were found low in treated adult male B. latifrons than normal male B. latifrons from 5th days of treatment until death. Kaplan-Meier survival analysis of treated male flies gave average survival times (AST) of 4.3?±?0.1 days, while the healthy female and male flies in the same cage showed AST of 9.3?±?0.3 and 8.3?±?0.4 days, respectively. The AST of untreated flies in control experiment ranged from 14.2–14.5 days. In mating preference experiment, M. guizhouense–treated male flies were chosen by virgin female than gravid female flies for mating. The treated male flies caused mortality in both virgin and gravid female flies in the same cage with AST of 4.4?±?0.1, 5.6?±?0.1 and 7.4?±?0.2 days, respectively, while untreated flies showed AST ranged from 13.9–14.3 days in control. The treated male flies could transmit the fungus infection to both untreated female and male flies as well as in virgin and gravid female flies by mating and contact. Our experiments showed the potentiality of M. guizhouense PSUM02 in management of B. latifrons by auto-dissemination with treated male flies, which transmit the fungus to a healthy population to reduce insect pest infestations. 相似文献
84.
Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an exotic species native to the USA, damaging cotton and other plant families. The
feeding potential of different development stages of Cryptolaemus montrouzieri Mulsant, a biological control agent against mealybugs, was investigated on different development stages of P. solenopsis. Fourth instar grubs and adults of C. montrouzieri were the most voracious feeders on different instars of mealybug. The number of 1st instar nymphs of mealybug consumed by 1st, 2nd, 3rd and 4th instar larvae and adult beetles of C. montrouzieri was 15.56, 41.01, 125.38, 162.69 and 1613.81, respectively. The respective numbers of 2nd and 3rd instar nymphs of mealybug consumed were 11.15 and 1.80, 26.35 and 6.36, 73.66 and 13.32, 76.04 and 21.16, 787.95 and 114.66.
The corresponding figures for adult female mealybugs were 0.94, 3.23, 8.47, 12.71 and 73.40, respectively. The results indicate
that C. montrouzieri has the potential to be exploited as a biocontrol agent in North India; inoculative releases of 4th instar larvae and adults may provide instant control of P. solenopsis. Field experiments should be conducted to determine the efficiency of the ladybird on this mealybug. 相似文献
85.
N. Mohammadi H. Puralibaba E. Mohammadi Goltapeh A. Babaie Ahari B. Pakdaman Sardrood 《Phytoparasitica》2012,40(1):69-76
Fusarium oxysporum f. sp. lentis is the most important pathogen of lentil plants, and most areas under lentil cultivation are reported to have a fusarium
wilt disease background. The plants are infected in the seedling stage and later stages of their development. Fusarium wilt
disease, which has appeared at high incidence rates during recent years, has caused sharp drops in the yield, especially in
Moghan, in the northwest of Iran. Forty-five isolates of the pathogen were collected from different regions of the country
with two isolates from ICARDA in the summer of 2008 and identified using Nelson’s key. The pathogenicity of the collected
isolates was studied on a sensitive line (ILL 4605) under greenhouse conditions and significant differences in pathogenicity
were found among them. The most pathogenic isolates from three provinces, East Azerbaijan (EA 30), Ardebil (Ar 3) and Khorasan
(Kh 45), were selected and used in screening of 55 developed lines under greenhouse and field conditions. In the greenhouse,
test plants were inoculated by immersing root tips in spore suspension and sowing seeds in pre-infested pot soil. Field tests
were carried out in a naturally highly infested farm. At all stages, the plant response to the disease was based on the percentage
of dead plants. Cluster analyses of the greenhouse and field data led to the selection of three lines (81S15, FLIP2007-42 L
and FLIP2009-18 L) that were resistant under greenhouse and field conditions. 相似文献
86.
S. Stankovic J. Levic T. Petrovic A. Logrieco A. Moretti 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(2):165-172
Fusarium proliferatum can occur on a wide range of economically important vegetable plants but its role in disease is not always well established.
In 2000 and 2001, from forty-one field samples of wilting onion and garlic plants in Serbia, F. proliferatum as the predominant fungal species was isolated from root and bulbs. Seventy isolates were firstly characterized for their
sexual fertility and were shown to be mostly members of Gibberella intermedia (sixty-seven of seventy isolates, the remaining three isolates were unfertile), the sexual stage of F. proliferatum (syn. mating population D of G. fujikuroi complex). A selected set of eleven F. proliferatum isolates from both hosts were also tested for their pathogenicity and toxigenicity. Although onion and garlic plants were
susceptible to all isolates, onion plants showed a significantly higher disease severity index. Six of the eleven isolates
of F. proliferatum produced fumonisin B1 from 25 to 3000 μg g−1, and beauvericin from 400 to 550 μg g−1; ten isolates produced fusaric acid from 80 to 950 μg g−1 and moniliformin from 50 to 520 μg g−1. Finally, all isolates produced fusaproliferin up to 400 μg g−1. These results confirm F. proliferatum as an important pathogen of garlic and onion in Europe and that there is a potential mycotoxin accumulation risk in contaminated
plants of both garlic and onion. 相似文献
87.
Hsiu-Lin Liu Ching-Chung Chen Chan-Pin Lin 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(3):281-291
Pear decline (PD) is an important phytoplasmal disease that occurs mainly in Europe and North America. In 1994, pear trees
exhibiting symptoms typical of PD disease were observed in orchards of central Taiwan. The sequence of 16S rDNA and 16S–23S
rDNA intergenic spacer region (ISR) of the causative agent of pear decline in Taiwan (PDTW) were amplified with polymerase
chain reaction (PCR) using a DNA template prepared from the diseased leaves. Sequence analysis of 16S rDNA revealed that the
PDTW agent was closely related to the phytoplasmas of the apple proliferation group that cause diseases in stone fruits, pear
and apple. Consistent with the result of 16S rDNA sequence analysis, sequence analysis of the 16S–23S rDNA ISR and putative
restriction site analyses of 16S rDNA and 16S–23S rDNA ISR sequences provided further support for the view that the PDTW phytoplasma
causing pear decline in Taiwan may represent a new subgroup of the apple proliferation group. According to the rDNA sequence
of PDTW phytoplasma, two specific PCR primer pairs, APf2/L1n and fPD1/rPDS1, were designed in this study for the detection
of the etiological agent in pear trees and insect vectors. Based on the sequence analyses of the PCR-amplified fragments,
two species of pear psyllas, Cacopsylla qianli and Cacopsylla chinensis, were found to carry PDTW phytoplasma. 相似文献
88.
Jeroen Peters Wojciech Sledz Jan H. W. Bergervoet Jan M. van der Wolf 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(2):97-107
An enrichment microsphere immunoassay (MIA) was developed, based on the Luminex xMAP® technology, for the simultaneous (duplex) detection of Pectobacterium atrosepticum (former name Erwinia carotovora subsp. atroseptica) (Pca) and Dickeya dianthicola (former name Erwinia chrysanthemi) (Dcd) in potato plant extracts. Target bacteria in the extracts were enriched for 48 h in a semi-selective broth containing polypectate under low oxygen conditions. Samples were subsequently incubated with antibody-coated colour-coded microspheres (beads) and with secondary antibodies conjugated with Alexa Fluor® 532, a reporter dye. Samples were analyzed with the Luminex analyzer, in which one laser identified each microsphere and another laser the reporter dye conjugated to the secondary antibodies. The assay required minimal sample preparation, could be completed in 1 h, was performed in 96 wells microtitreplates and required no wash steps. The limit of detection for the duplex enrichment MIA was 100–1000 cfu ml?1, which was a hundred times lower than of an enrichment-ELISA. Without enrichment, the sensitivity of MIA and ELISA was largely similar and ranged between 106 and 107 cells ml?1. No difference in sensitivity was found between a MIA in a single or duplex format. In a comparative test with non-infected potato plant extracts and extracts from plants infected with Pca or Dcd, results of the enrichment MIA correlated well with those of the enrichment ELISA and enrichment PCR. These results indicate that MIA can be reliably used for multiplex detection of soft rot Enterbacteriaceae in crude potato plant extracts. The technology is an attractive and cost-effective alternative to other detection methods, including ELISA. 相似文献
89.
Domenico Rongai Claudio Cerato Luca Lazzeri 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(4):613-619
This study examines the effects of a vegetable fungicide on sugar beet powdery mildew (Erysiphe betae) and cucumber powdery mildew (Erysiphe cichoracearum). The formulations consisting of a dispersion of Brassicaceae meal in vegetable or mineral oils on infected leaves of sugar beet, reared in the greenhouse, and of musk melons cultivated
under plastic tunnels, were tested in comparison to each oil taken separately. Both formulations containing Brassicaceae meals, caused 94% of conidia to be distorted while for the untreated group only 2% were distorted. Furthermore, the leaf
area infected by E. betae was 56% for untreated plants and 2.7 and 9.9% respectively, for plants treated with meal containing mineral and vegetable
oil. Vegetable oil considered separately or with Brassicaceae meals showed no phytotoxicity, while the formulations based on mineral oil showed a significantly lower fresh and dry weight
on tomato plants. The low level or absence of phytotoxicity of plants treated with vegetable oil formulations suggests that
to improve the efficacy of powdery mildew control, they could be used mixed with sulphur. The efficiency of the vegetable
formulations in the powdery mildew control observed during these trials encourages further investigation on other parasitic
fungi and foliar pathogens. 相似文献
90.
Erich Seemüller Eckard Moll Bernd Schneider 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(2):217-223
Progenies of 39 open-pollinated genotypes belonging to 26 Pyrus taxa were examined for pear decline resistance and pomological traits when used as rootstocks. Following graft inoculation
and observation over 18 years, considerable differences in pear decline resistance between and within the progenies were observed.
Not affected or little affected and moderately to severely affected trees were observed in all progenies. However, great quantitative
differences among them were observed. In the progenies of about one third of the pollinated trees most of the individuals
showed a high level of resistance to grafted trees. Significantly different from this group was another third of the progenies
that mostly showed high susceptibility in grafted trees. Between these two groups there were progenies that statistically
neither differed from the resistant nor from the susceptible group. These progenies were defined as moderately resistant.
Significant differences in resistance were also observed between progenies of genotypes of the same species that originated
from different locations. These data indicate segregation of the resistance trait and show that seedling progenies are unsuitable
as rootstocks in commercial pear growing. Instead, careful selection of suitable genotypes for propagation is required. Great
differences between and within the progenies examined were also observed in vigour and yield efficiency. 相似文献