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1.
A weed survey conducted in 2004 and 2005 in Aydin province of Turkey showed that Solanum nigrum, Xanthium strumarium, Amaranthus retroflexus, Portulaca oleracea, Sonchus oleraceus and Datura stramonium were the most prevalent weeds in the cotton fields exhibiting Verticillium wilt. Verticillium dahliae Kleb. was recovered from A. retroflexus and X. strumarium in those cotton fields. This is the first report of V. dahliae occurring naturally in A. retroflexus in Turkey. Pathogenicity tests on cotton and weeds showed that the virulence of V. dahliae isolates from weeds was higher on cotton plants than on weeds, with the disease severity ranging from 31.7% to 98.0%. Disease
severity of V. dahliae isolates was 54.7–93.9% on eggplant, 23.7–51.6% on cucumber and 11.0–16.4% on tomato, whereas it did not cause any disease
symptoms, or only low levels, on pepper and bell pepper. Two vegetative compatibility groups (VCGs) were identified among
seven tested weed isolates: VCG2A (two isolates) and VCG2B (three isolates) using international reference strains. 相似文献
2.
Mehmet Erhan Göre 《Phytoparasitica》2009,37(1):87-94
A collection of 30 strains of Verticillium dahliae, recovered during 2004–2006 from 12 cultivars of chrysanthemum (Chrysanthemum morifolium) in five districts of İzmir province in Turkey, was assigned to vegetative compatibility groups (VCGs) based on pairings
of complementary nitrate-nonutilizing (nit) mutants induced on a chlorate-containing medium. Of these strains, nine were assigned to VCG1, seven to VCG2A, 11 toVCG2B
and one to VCG4B. The remaining two strains could not be tested for vegetative compatibility because of their inability to
yield nit mutants. Pathogenicity tests conducted by the root-dip method, demonstrated that wilt of chrysanthemum in Turkey is caused
by V. dahliae, and most strains in VCG1 were significantly more aggressive to chrysanthemum than those in VCGs 2 and 4B. This is the first
known study in the world of the VCGs of V. dahliae isolates from chrysanthemum. 相似文献
3.
Sibel Dervis Latife Erten Soner Soylu Fatih M. Tok Sener Kurt Mehmet Yıldız E. Mine Soylu 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):437-447
Verticillium wilt, caused by Verticillium dahliae, is the most serious disease in olive cultivation areas in western Turkey. Two hundred and eight isolates of V. dahliae from olive (Olea europea var. sativa) trees were taken for vegetative compatibility analysis using nitrate non-utilizing (nit) mutants. One isolate did not produce a nit mutant. Nit mutants of 207 isolates were tested against tester strains of internationally known vegetative compatibility groups (VCGs) 1A, 2A, 2B, 3, 4A and 4B, and also paired in many combinations among themselves. One hundred and eighty nine of the isolates (90.9%) were strongly compatible with T9, the tester strain of VCG1A, and thus were assigned to VCG1A. Eight isolates were assigned to VCG2A and four isolates to VCG4B. One isolate was heterokaryon self-incompatible (HSI) and five isolates could not be grouped to any of the VCGs tested. Pathogenicity assays were conducted on a susceptible olive cultivar (O. europea cv. Manzanilla) and a susceptible local cotton cultivar (Gossypium hirsutum cv. Çukurova 1518). Both cotton and olive inoculated with all VCG1A isolates showed defoliating symptoms in greenhouse tests. This is the first report on VCGs in V. dahliae from olive trees in Turkey which demonstrates that VCG1A of the cotton-defoliating type is the most commonly detected form from olive plants in the western part of Turkey. 相似文献
4.
Natural recovery from wilt disease symptoms was evaluated in young olive trees root dip inoculated with Verticillium dahliae in a growth chamber over a 12 week period and, later on, when the trees were transplanted in a V. dahliae-free soil in a lathhouse during a period of 127 weeks. Recovery in an individual tree was considered when a plant showed
symptom remission after having reached a maximum value of symptom severity. Recovery accounted for 53% of 464 trees that showed
wilt symptoms during observations in the two environments. The remaining trees died. Recurrent wilt symptoms were not observed
in recovered trees, and recovery was usually accompanied by the production of new green tissues. Recovery was clearly higher
in trees inoculated with a non-defoliating (ND) isolate (86.4%) of the pathogen than in those inoculated with a defoliating
(D) isolate (23.9%). The percentage of recovery and the level of resistance were significantly correlated. Recovery accounted
for 92.1% of the cases in resistant and moderately susceptible cultivars, reaching 100% in plants inoculated with the ND isolate
(Table 2); meanwhile it was three times lower (30.1% of the plants) in susceptible and extremely susceptible diseased trees.
In the lathhouse, periodical tissue isolations for monitoring the progress of infections over a period of 127 weeks in recovered
trees, showed that the pathogen could only be isolated from trees 19 weeks after inoculation. Pathogen isolation was significantly
higher from susceptible and extremely susceptible cultivars (84.6%) than from resistant and moderately susceptible ones (33.3%).
Results showed that if a tree overcomes infection by pathogen from a single inoculation, and it is able to begin a recovery
process, it will not express wilt symptoms again in a pathogen-free environment. The pathogen remained inactive or dead over
time in recovered trees. Thus, new infections from rootlets would be necessary for new symptom expression. Recovery from Verticillium wilt is an important natural mechanism that occurs in a high percentage of infected olive trees, and can complement the resistance
of the cultivar, particularly in conditions of low inoculum densities of low virulence isolates of the pathogen in the soil. 相似文献
5.
Toshiyuki Usami Mizuho Itoh Yoshimiki Amemiya 《Journal of General Plant Pathology》2009,75(6):422-427
Verticillium dahliae, a soilborne plant pathogen, causes wilt disease in many important crops. We reported previously that the mating type gene
MAT1-2-1 is spread to isolates of this asexual fungus. However, we did not determine whether V. dahliae is homothallic or heterothallic because the opposite mating type gene, MAT1-1-1, had not been identified. In the present study, we identified the MAT1-1-1 gene from an isolate lacking MAT1-2-1 and the mating type idiomorphs of V. dahliae. Each isolate we tested contained either the MAT1-1 or MAT1-2 idiomorph, indicating that the asexual fungus V. dahliae is potentially heterothallic. 相似文献
6.
H. Alkher A. El Hadrami K. Y. Rashid L. R. Adam F. Daayf 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):505-519
This study examined cross-pathogenicity of the soilborne pathogen Verticillium dahliae between potato and sunflower. Four week-old potato and sunflower seedlings were inoculated with ten isolates from each of
the two host species. Potato cultivars (Kennebec, susceptible, and Ranger Russet, moderately resistant) and sunflower hybrids
(IS8048, susceptible, and 6946, moderately resistant) were assessed for disease severity and percent infection at 2 weeks,
3 weeks, 4 weeks, 5 weeks, and 6 weeks after inoculation (w.a.i), and for vascular discolouration at 6 w.a.i., using visual
scales developed for each host species. The experiments were conducted in 2006 and repeated in 2007. Based on percent infection
and disease severity, most V. dahliae isolates were highly aggressive on both host species. The tested isolates caused higher disease levels in the susceptible
than in the moderately resistant phenotypes. They also caused more vascular discolouration in their original than in the alternative
host. However, the isolates originating from sunflower caused less infection and disease severity on both hosts, compared
to their potato counterparts. Cluster analysis based on all of the criteria used to assess pathogenicity led to three groups
of isolates: (i) most V. dahliae potato isolates, which ranged with the highly aggressive control isolates, (ii) one V. dahliae sunflower isolate, which showed a similar pathogenicity level to the weakly-aggressive V. albo-atrum sub-group II control isolate, with no more symptoms than in the non-inoculated plants, and (iii) most V. dahliae sunflower isolates with mildly- to weakly-aggressive levels. Based on these results, V. dahliae cross-pathogenicity is very effective between potato and sunflower. Therefore, rotations involving these species should be
avoided, especially where sunflower follows potato. 相似文献
7.
The chromosome number and electrophoretic karyotype of Japanese isolates of Verticillium dahliae were investigated. In a genomic Southern blot analysis of seven isolates probed with a telomere consensus sequence (TTAGGG)5, 12 or 14 bands were observed. Furthermore, pulsed-field gel electrophoresis (PFGE) of these isolates revealed five or six
chromosomal bands. A band (approx. 3.5 Mbp) common to all isolates apparently contained more than two chromosomes. From these
results, we concluded that each isolate’s chromosome number is six (an eggplant pathotype isolate) or seven (all isolates
of tomato and sweet pepper pathotypes). Although the chromosome sizes differed among isolates, karyotypes were similar within
tomato and sweet pepper pathotypes. A small chromosome (approx. 1.8 Mbp) was observed only in the sweet pepper pathotype.
Subsequent PFGE-Southern hybridization analyses revealed that the three DNA fragments specific to tomato pathotype are located
on the same chromosome. These results suggest that the tomato-pathotype-specific DNA sequences might coexist on one chromosome. 相似文献
8.
Fusarium wilt is an economically important fungal disease of common eggplant (Solanum melongena) cultivated in the eastern Mediterranean region of Turkey. Seventy-four isolates of Fusarium oxysporum isolated from diseased eggplant displaying typical Fusarium wilt symptoms were screened for pathogenicity on the highly susceptible
cv. ‘Pala’. All the isolates tested were pathogenic to eggplant and designated as Fusarium oxysporum f. sp. melongenae (Fomg). Genetic diversity among a core set of 20 Fomg isolates that were selected based upon geographic locations, were characterized by using pathogenicity, vegetative compatibility
grouping (VCG), and random amplified polymorphic DNA (RAPD) analysis. The area under the disease progress curve (AUDPC) was
calculated for each Fomg isolate until 21 days after inoculation (DAI). The most virulent isolate was identified as Fomg10 based on AUDPC, disease severity and vascular discoloration measurements at 21 DAI. At this date, a good correlation was
observed between disease severity and AUDPC values for all isolates (r = 0.73). UPGMA (unweighted pair group method with arithmetic average) cluster analysis of RAPD data using Dice’s coefficient
of similarity differentiated all the Fomg isolates tested, and indicated considerable genetic variation among Fomg isolates, but isolates from the same geographic region were grouped together. There was no direct correlation between clustering
in the RAPD dendrogram and pathogenicity testing of Fomg isolates. Twenty isolates of Fomg were assigned to VCG 0320. 相似文献
9.
Shinpei Banno Hidenari Saito Hiroshi Sakai Toshihiko Urushibara Kentaro Ikeda Takeshi Kabe Isao Kemmochi Makoto Fujimura 《Journal of General Plant Pathology》2011,77(5):282-291
Verticillium longisporum and V. dahliae, causal agents of Verticillium wilt, are spreading through the cabbage fields of Gunma Prefecture. Using the V. longisporum-specific intron within the 18S rDNA and differences between ITS 5.8S rDNA sequences in Japanese isolates of V. longisporum and V. dahliae, we developed three quantitative nested real-time (QNRT) PCR assays. The QNRT-PCR quantification of V. longisporum or V. dahliae in cabbage field soil was consistent with the severity of Verticillium wilt disease in those fields. In field trials of resistant
cultivar YR Ranpo grown for three seasons in soil infested with the pathogen, disease severity and pathogen density in the
soil were significantly reduced in a field moderately contaminated by V. dahliae, but only slightly reduced in a highly contaminated field. These results suggest that continuous cultivation of a resistant
cultivar is an effective way to reduce the pathogen population. QNRT-PCR assays provide a powerful analytical tool to evaluate
the soil population dynamics of V. longisporum and V. dahliae for disease management. 相似文献
10.
Guillermo A. Galván Carole F. S. Koning-Boucoiran Wim J. M. Koopman Karin Burger-Meijer Pablo H. González Cees Waalwijk Chris Kik Olga E. Scholten 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(4):499-512
The aim of this research was to study levels of resistance to Fusarium basal rot in onion cultivars and related Allium species, by using genetically different Fusarium isolates. In order to select genetically different isolates for disease testing, a collection of 61 Fusarium isolates, 43 of them from onion (Allium cepa), was analysed using amplified fragment length polymorphism (AFLP) markers. Onion isolates were collected in The Netherlands
(15 isolates) and Uruguay (9 isolates), and received from other countries and fungal collections (19 isolates). From these
isolates, 29 were identified as F. oxysporum, 10 as F. proliferatum, whereas the remaining four isolates belonged to F. avenaceum and F. culmorum. The taxonomic status of the species was confirmed by morphological examination, by DNA sequencing of the elongation factor
1-α gene, and by the use of species-specific primers for Fusarium oxysporum, F. proliferatum, and F. culmorum. Within F. oxysporum, isolates clustered in two clades suggesting different origins of F. oxysporum forms pathogenic to onion. These clades were present in each sampled region. Onion and six related Allium species were screened for resistance to Fusarium basal rot using one F. oxysporum isolate from each clade, and one F. proliferatum isolate. High levels of resistance to each isolate were found in Allium fistulosum and A. schoenoprasum accessions, whereas A. pskemense, A. roylei and A. galanthum showed intermediate levels of resistance. Among five A. cepa cultivars, ‘Rossa Savonese’ was also intermediately resistant. Regarding the current feasibility for introgression, A. fistulosum, A. roylei and A. galanthum were identified as potential sources for the transfer of resistance to Fusarium into onion. 相似文献
11.
Effects of crop rotation between rice paddy fields and strawberry nurseries on the control of Verticillium wilt of strawberry
were studied. For detecting Verticillium dahliae, the causal agent of Verticillium wilt, in soil, eggplant was used as an indicator plant. We were thus able to detect as
low as 1 microsclerotium/g dry soil. In field surveys of Chiba and Hokkaido from 2000 to 2003, V. dahliae was detected in 9 of 10 upland fields but in none of 21 paddy-upland fields. In Hokkaido during 2000–2007, strawberry mother
plants were planted, and plantlets were produced in upland and paddy-upland fields to assess V. dahliae infestation. Verticillium wilt of strawberry had never occurred in 72 tested paddy-upland fields, compared to 13.2–73.9%
of plantlets infected with V. dahliae in upland fields. In a pot experiment in a greenhouse, two flooding treatments or two paddy rice cultivations suppressed
Verticillium wilt symptoms on eggplant. In field experiments, one paddy rice cultivation in Chiba and two in Hokkaido prevented
development of Verticillium wilt symptoms on eggplant. Verticillium wilt of strawberry was controlled completely with one
paddy rice cultivation in infested fields in Chiba. In these field experiments, the number of microsclerotia of V. dahliae decreased under the flooding conditions for paddy rice cultivation. Based on the reduction in microsclerotia, a crop rotation
system with paddy rice for 3 years (three times), green manure for 1 year, and strawberry nursery for 1 year was designed
for Hokkaido. 相似文献
12.
Alireza Akhavan T. Kelly Turkington Berisso Kebede Kequan Xi Krishan Kumar Andy Tekauz H. Randy Kutcher James R. Tucker Stephen E. Strelkov 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(2):325-336
Infection by Pyrenophora teres f. teres (Ptt) or P. teres f. maculata (Ptm), the causal agents of the net and spot forms of net blotch of barley, respectively, can result in significant yield losses. The genetic structure of a collection of 128 Ptt and 92 Ptm isolates from the western Canadian provinces of Alberta (55 Ptt, 27 Ptm), Saskatchewan (58 Ptt, 46 Ptm) and Manitoba (15 Ptt, 19 Ptm) were analyzed by simple sequence repeat (SSR) marker analysis. Thirteen SSR loci were examined and found to be polymorphic within both Ptt and Ptm populations. In total, 110 distinct alleles were identified, with 19 of these shared between Ptt and Ptm, 75 specific to Ptt, and 16 specific to Ptm. Genotypic diversity was relatively high, with a clonal fraction of approximately 10 % within Ptt and Ptm populations. Significant genetic differentiation (PhiPT = 0.230, P = 0.001) was found among all populations; 77 % of genetic variation occurred within populations and 23 % between populations. Lower, but still significant genetic differentiation (PhiPT = 0.038, P = 0.001) was detected in Ptt, with 96 % of genetic variation occurring within populations. No significant genetic differentiation (PhiPT = 0.010, P = 0.177) was observed among Ptm populations. Isolates clustered in two distinct groups conforming to Ptt or Ptm, with no intermediate cluster. The high number of haplotypes observed, combined with an equal mating type ratio for both forms of the fungus, suggests that P. teres goes through regular cycles of sexual recombination in western Canada. 相似文献
13.
Serap Mutun 《Phytoparasitica》2009,37(1):65-66
An invasive Tingidae, the platanus lace bug Corythucha ciliata (Say, 1832) (Hemiptera: Tingidae), which specializes on Platanus spp., was found for the first time in Turkey in 2007; it was recorded from a 120 km2 area in the northwestern part of the country. Infestations occurred in an area between Taşkesti and Abant in Bolu Province,
which is located near major cities and two main motorways. The pest species is newly spreading in Turkey, causing noticeable
damage to Platanus orientalis trees. 相似文献
14.
Akira Kawaguchi 《Journal of General Plant Pathology》2011,77(5):299-303
Forty-one strains of Rhizobium vitis, either tumorigenic (Ti) or nonpathogenic, were characterized using multilocus sequence analysis (MLSA) of the partial nucleotide
sequences of pyrG, recA, and rpoD. The strains separated into seven clades. Rhizobium vitis (Ti) strains isolated from Japan were divided into five genetic groups (A to E), and nonpathogenic R. vitis strains were divided into two genetic groups (F and G). This result suggests that there are new genetic groups of R. vitis in Japan. Among these groups, members of A and B groups are widely distributed throughout Japan. 相似文献
15.
From the genome of a Japanese field isolate of the rice blast fungus, Magnaporthe oryzae, we newly identified Inago1 and Inago2 LTR retrotransposons. Both elements were found to be Ty3/gypsy-like elements whose copies were dispersed within the genome of Magnaporthe spp. isolates infecting rice and other monocot plants. Southern hybridization patterns of nine re-isolates derived from conidia
of the strain Ina168 produced after a methyl viologen treatment were not changed, indicating that the insertion pattern of
Inago elements is relatively stable. 相似文献
16.
Masamichi Isogai Koji Ishii Seisaku Umemoto Manabu Watanabe Nobuyuki Yoshikawa 《Journal of General Plant Pathology》2009,75(2):140-143
Virus-like symptoms—red ringspots on stems and leaves, circular blotches or pale spots on fruit—were found on commercial highbush
blueberry (Vaccinium
corymbosum) cultivars Blueray, Weymouth, Duke and Sierra in Japan. In PCR testing, single DNA fragments were amplified from total nucleic
acid samples of the diseased blueberry bushes using primers specific to Blueberry red ringspot virus (BRRV). Sequencing analysis of the amplified products revealed 95.7–97.7% nucleotide sequence identity with the BRRV genome.
This paper is the first report of blueberry red ringspot disease caused by BRRV in Japan.
The nucleotide sequence data reported in this paper are available in the GenBank/EMBL/DDBJ database as accessions AB469884
to AB469893 for BRRV isolates from Japan. 相似文献
17.
Hüseyin Basım Esin Basım Derya Baki Muntala Abdulai Nurhan Öztürk Recep Balkic 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(1):73-90
A new dagger nematode, Xiphinema tica n. sp., is described and illustrated from several populations extracted from soil associated with several crops and wild plants in Costa Rica. The new dagger nematode is characterised by a moderate body size (3276–4240 μm), a rounded lip region, ca 13.5 μm wide, separated from body contour by a shallow depression, amphidial fovea large, stirrup-shaped, a moderately long odontostyle ca 135 μm long, stylet guiding ring located at ca 122 μm from anterior end, vulva almost equatorial (50–54%), well-developed Z-organ, with heavy muscularised wall containing in the most of specimens observed two moderately refractive inclusions variable in shape (from round to star-shaped), with uterine spines and crystalloid bodies; female tail short, dorsally convex-conoid, with rounded end and a small peg, with a c’ ratio ca 0.8, bearing two or three pairs of caudal pores and male absent. The unique and novel uterine differentiation based on the coexistence of a well-developed Z-organ mixed with uterine spines and crystalloid bodies in Xiphinema prompted us to update and include this combination of characters in the polytomous key of Loof and Luc (1990). Integrative diagnosis was completed with molecular data obtained, using D2-D3 expansion segments of 28S rDNA, ITS1-rDNA, partial 18S–rDNA and the partial mitochondrial gene cytochrome c oxidase subunit 1 (coxI). The phylogenetic relationships of this species with other Xiphinema spp. indicated that X. tica n. sp. was monophyletic to the other species from the morphospecies Group 4, Xiphinema oleae. 相似文献
18.
Mathias De Backer Hossein Alaei Erik Van Bockstaele Isabel Roldan-Ruiz Theo van der Lee Martine Maes Kurt Heungens 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(3):325-338
Puccinia horiana is the causal agent of chrysanthemum white rust or Japanese rust. This microcyclic autoecious rust has a quarantine status
and can cause major damage in the commercial production of Chrysanthemum x morifolium. Given the international and often trans-continental production of planting material and cut flowers of chrysanthemum and
the decreasing availability of registered fungicides in specific regions, breeding for resistance against P. horiana will gain importance and will need to involve the appropriate resistance genes for the pathotypes that may be present. As
pathotypes have not been well characterized in this system, the main objective was to build an international collection of
isolates and screen these on a large collection of cultivars to identify different pathotypes. Using a robust and high throughput
bioassay, we tested 36 selected cultivars with 22 individual single-pustule isolates of P. horiana. The isolates originated from three different continents over 4 different collection years and included some isolates from
cultivars previously reported as resistant. In most cases the bioassays resulted in a clear scoring of interaction phenotypes
as susceptible or resistant, while in several cases consistent intermediate phenotypes were found, often on specific cultivars.
Twenty-four of the cultivars gave a differential interaction phenotype profile. All isolates produced a unique profile, infecting
a minimum of 4 and a maximum of 19 differential cultivars. Based on the Person analysis of these profiles, this pathosystem
contains at least seven resistance genes (and seven avirulence genes), demonstrating the highly complex race structure in
this pathosystem. 相似文献
19.
Khalid A. Hussein Mohamed A. A. Abdel-Rahman Ahmed Y. Abdel-Mallek Saad S. El-Maraghy Jin Ho Joo 《Phytoparasitica》2012,40(2):117-126
The greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) is occasionally found in beehives and is a major pest of stored wax. Entomopathogenic fungi have
recently received attention as possible biocontrol elements for certain insect pests. In this study, 90 isolates of Beauveria bassiana and 15 isolates of Metarhizium anisopliae were screened for proteases and lipases production. The results showed significant variations in the enzymatic action between
the isolates. In the bioassay, the selected isolates evinced high virulence against the 4th instar of the G. mellonella larvae. The isolates BbaAUMC3076, BbaAUMC3263 and ManAUMC3085 realized 100% mortality at concentrations of 5.5 × 106 conidia ml−1, 5.86 × 105 conidia ml−1, and 4.8 × 106 conidia ml−1, respectively. Strong enzymatic activities in vitro did not necessarily indicate high virulence against the tested insect pest. The cuticle of the infected larvae became dark
and black-spotted, indicating direct attack of fungus on the defense system of the insects. The LC50 values were 1.43 × 103, 1.04 × 105 and 5.06 × 104 for Bba3263AUMC, Bba3076AUMC and Man3085AUMC, respectively, and their slopes were determined by computerized probit analysis
program as 0.738 ± 0.008, 0.635 ± 0.007 and 1.120 ± 0.024, respectively. 相似文献
20.
Bruna B. Brumer Valéria S. Lopes-Caitar Aline S. Chicowski Jessica D. Beloti Fernanda M. Castanho Danielle C. Gregório da Silva Sandremir de Carvalho Ivani O. N. Lopes Rafael M. Soares Claudine D. S. Seixas Ricardo V. Abdelnoor Francismar C. Marcelino-Guimarães 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(4):1009-1025
The complex of Diaporthe (asexual morph) species occurring on soybean constitutes an important pathogenic group associated with diseases such as pod and stem blight, seed decay and stem canker. Stem canker, caused by Diaporthe aspalathi, has been reported as the most aggressive form of canker and its occurrence has limited soybean crop productivity in the southern United States. The main form of pathogen control is the use of stem canker resistant soybean varieties. In this study, strains of Diaporthe and Phomopsis were isolated from stem and seeds of soybean in different locations in South America during the years 1989–2014. Genomic DNA from 26 isolates were analyzed by PCR-restriction fragment length polymorphism (RFLP) and Amplified Fragment Length Polymorphism (AFLP) techniques, and sequencing of internal transcribed spacer (ITS) regions of ribosomal DNA. The molecular analysis of ITS sequences by alignment with those of ex-type strains deposited in GenBank and morphological characteristics allowed the identification of Phomopsis longicolla, D. phaseolorum var. sojae, D. caulivora and D. aspalathi. An analysis of the pathogenicity of 13 isolates of D. aspalathi inoculated in soybean genotypes carrying different resistance genes to stem canker (Rdm1, Rdm2, Rdm3, Rdm4, Rdm5 and Rdm?) enabled us to identify the occurrence of at least three races of D. aspalathi occurring in Brazil. Among the isolates identified as D. aspalathi, both molecular and phenotypic analyses showed clustering depending on the date of collection and pathogenicity, which revealed the existence of variability of the pathogen. 相似文献