scholarly journals Genetic Diversity and Aggressiveness of Ophiosphaerella korrae, a Cause of Spring Dead Spot of Bermudagrass

Plant Disease ◽  
2004 ◽  
Vol 88 (12) ◽  
pp. 1341-1346 ◽  
Author(s):  
F. B. Iriarte ◽  
H. C. Wetzel ◽  
J. D. Fry ◽  
D. L. Martin ◽  
N. A. Tisserat
Keyword(s):  
Genetic Diversity ◽  
North Carolina ◽  
Fragment Length Polymorphism ◽  
Southeastern United States ◽  
Kentucky Bluegrass ◽  
Potato Dextrose Agar ◽  
Group Iii ◽  
Spring Dead Spot ◽  
Group I ◽  
Ophiosphaerella Korrae

The distribution of three Ophiosphaerella spp. that cause spring dead spot (SDS) of bermudagrass was studied by sampling at 24 locations in the southeastern United States. O. korrae was isolated from 73% of the 204 bermudagrass cores collected and was the only SDS pathogen recovered at most sites. O. herpotricha was isolated at three locations in Kentucky and one in North Carolina, and O. narmari was found at two locations in North Carolina. Most O. korrae isolates collected from Alabama, Kentucky, Mississippi, Tennessee, and Virginia clustered in an amplified fragment length polymorphism group (AFLP group II) that was distinct from Kentucky bluegrass isolates collected throughout North America and similar to bermudagrass isolates from Kansas and Oklahoma (AFLP group I). A third AFLP group (III) consisting of bermudagrass isolates from Mississippi and Virginia was identified. Isolates representing AFLP groups II and III grew more rapidly on potato dextrose agar at 25 and 30°C than those in group I. O. korrae isolates differed in their aggressiveness to two bermudagrass cultivars in greenhouse studies, but these differences were not associated with AFLP group, location, or host from which the isolate was collected.

scholarly journals Geographic Distribution and Genetic Diversity of Three Ophiosphaerella Species that Cause Spring Dead Spot of Bermudagrass

Plant Disease ◽  
1999 ◽  
Vol 83 (12) ◽  
pp. 1160-1166 ◽  
Author(s):  
Henry C. Wetzel ◽  
Daniel Z. Skinner ◽  
Ned A. Tisserat
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
North America ◽  
Fragment Length Polymorphism ◽  
Kentucky Bluegrass ◽  
Abundant Species ◽  
Golf Courses ◽  
Asexual Propagation ◽  
Spring Dead Spot ◽  
Sexual Recombination

The distribution of three Ophiosphaerella spp. that cause spring dead spot (SDS) of bermudagrass was studied by systematically sampling two golf courses in Oklahoma and one in Kansas. O. herpotricha was isolated from all three locations and was the most abundant species. It was the only SDS pathogen found at Jenks, Oklahoma. O. korrae was isolated from Afton, Oklahoma, and Independence, Kansas, whereas O. narmari was only detected in samples from Afton. This is the first report of all three Ophiosphaerella species on bermudagrass at the same location. Amplified fragment length polymorphism (AFLP) marker analysis was used to investigate inter- and intraspecific genetic diversity of Ophiosphaerella isolates from North America and Australia. A majority of the O. herpotricha and O. narmari isolates from Afton were distinct haplotypes, suggesting that sexual recombination was occurring within the population. Conversely, the presence of multiple isolates of O. herpotricha and O. narmari with the same haplotype also indicated that asexual propagation was occurring. The genetic diversity among O. herpotricha isolates from Afton was not distinctly different from that of isolates collected throughout the southern United States. In contrast, O. narmari isolates from Afton were distinct from those collected in Australia. The genetic diversity in O. korrae was markedly different than that in the other Ophiosphaerella spp. The population at Afton was dominated by just a few haplotypes, and these were nearly identical to isolates collected from bermudagrass and Kentucky bluegrass throughout western, central, and northern North America. However, O. korrae isolates collected in the southeastern United States were only distantly similar to other North American isolates.

THE PREVALENCE OF INTRADERMAL SENSITIVITY TO VARIOUS MYCOBACTERIAL ANTIGENS IN A GROUP OF HEALTHY CHILDREN IN SOUTHEASTERN UNITED STATES

PEDIATRICS ◽  
1966 ◽  
Vol 38 (3) ◽  
pp. 381-387
Author(s):  
Henry G. Cramblett ◽  
C. M. F. Siewers ◽  
Elizabeth W. Edmond ◽  
Jeanette Crews
Keyword(s):  
North Carolina ◽  
Southeastern United States ◽  
Group Iv ◽  
School Age Children ◽  
Healthy Children ◽  
School Age ◽  
Group Iii ◽  
Children's Home ◽  
White School ◽  
Mycobacterial Antigens

Two hundred seventy-four healthy white school-age children residing in a children's home in northwestern North Carolina were tested intradermally with 5 tuberculin units of PPD-Watson (Group II), PPD-Battey (Group III), PPD-S (Mycobacterium tuberculosis), and PPD-Phlei (Group IV). Ninety per cent of the children had at least one positive reaction (2 mm or more of mean induration) at one or more of five readings (24 hr, 48 hr, 72 hr, 96 hr, and 168 hr). The most frequent reactions were to PPD-Watson. In 22 children, positive responses to PPD-S were probably cross-reactions as a result of infection with one or more atypical mycobacteria.

scholarly journals Rapid Identification and Differentiation of the Soft Rot Erwinias by 16S-23S Intergenic Transcribed Spacer-PCR and Restriction Fragment Length Polymorphism Analyses

2001 ◽  
Vol 67 (9) ◽  
pp. 4070-4076 ◽  
Author(s):  
I. K. Toth ◽  
A. O. Avrova ◽  
L. J. Hyman
Keyword(s):  
Restriction Fragment Length Polymorphism ◽  
Restriction Fragment ◽  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Soft Rot ◽  
Group Iii ◽  
Group I ◽  
Its Pcr ◽  
Restriction Fragment Length

ABSTRACT Current identification methods for the soft rot erwinias are both imprecise and time-consuming. We have used the 16S-23S rRNA intergenic transcribed spacer (ITS) to aid in their identification. Analysis by ITS-PCR and ITS-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. The ITS was amplified fromErwinia and other genera using universal PCR primers. After PCR, the banding patterns generated allowed the soft rot erwinias to be differentiated from all other Erwinia and non-Erwinia species and placed into one of three groups (I to III). Group I comprised all Erwinia carotovorasubsp. atroseptica and subsp.betavasculorum isolates. Group II comprised allE. carotovora subsp. carotovora,subsp. odorifera, and subsp. wasabiae andE. cacticida isolates, and group III comprised allE. chrysanthemi isolates. To increase the level of discrimination further, the ITS-PCR products were digested with one of two restriction enzymes. Digestion with CfoI identified E. carotovora subsp.atroseptica and subsp. betavasculorum(group I) and E. chrysanthemi (group III) isolates, while digestion with RsaI identified E. carotovora subsp. wasabiae, subsp. carotovora, and subsp.odorifera/carotovora and E. cacticida isolates (group II). In the latter case, it was necessary to distinguishE. carotovora subsp. odorifera and subsp. carotovora using the α-methyl glucoside test. Sixty suspected soft rot erwinia isolates from Australia were identified as E. carotovora subsp.atroseptica, E. chrysanthemi,E. carotovora subsp. carotovora, and non-soft rot species. Ten “atypical” E. carotovora subsp. atroseptica isolates were identified as E. carotovora subsp.atroseptica, subsp. carotovora, and subsp. betavasculorum and non-soft rot species, and two “atypical” E. carotovora subsp.carotovora isolates were identified as E. carotovora subsp. carotovora and subsp.atroseptica.

scholarly journals DIVERSITAS GENETIK TUJUH AKSESI PLASMA NUTFAH PINANG (Areca catechu L.) ASAL PULAU SUMATERA

2020 ◽  
Vol 12 (1) ◽  
pp. 27
Author(s):  
MIFTAHORRACHMAN MIFTAHORRACHMAN
Keyword(s):  
Genetic Diversity ◽  
Genetic Distance ◽  
Population Genetic ◽  
Group Iv ◽  
Group Iii ◽  
Know How ◽  
North Sulawesi ◽  
Group I ◽  
Areca Catechu ◽  
Experimental Garden

ABSTRAK<br />Analisis jarak genetik dilakukan terhadap tujuh populasi pinang<br />(Areca catechu L.), yaitu Sumut-1, Sumut-2, Sumbar-1, Sumbar-2,<br />Sumbar-3, Bengkulu-1 dan Bengkulu-2 hasil eksplorasi pada tahun 1994<br />dan telah dikoleksi di kebun koleksi plasma nutfah palma Kayuwatu,<br />Sulawesi Utara. Tujuan analisis adalah untuk mengetahui seberapa besar<br />jarak  genetik  antara  ke  tujuh  aksesi  pinang  sekaligus  untuk<br />mengelompokkan ketujuh aksesi tersebut. Analisis menggunakan Uji<br />Statistik D 2 dari Mahalanobis, sedangkan untuk pengelompokan populasi<br />menggunakan metode Tocher yang dikemukakan oleh RAO dalam SINGH<br />dan CHAUDARY. Hasil analisis menunjukkan bahwa ketujuh aksesi<br />pinang membentuk 4 kelompok yaitu, kelompok I terdiri dari aksesi<br />Sumbar-1 dan Sumut-1; kelompok II terdiri dari 3 aksesi yaitu Sumbar-3,<br />Sumut-2 dan Bengkulu-1; kelompok III dan kelompok IV masing-masing<br />hanya terdapat satu aksesi yaitu Sumbar-2 dan Bengkulu-2. Jarak genetik<br />paling jauh adalah antara kelompok I dan II dengan nilai D 2 = 1263.137.<br />Sementara jarak genetik antar kelompok terdekat adalah antara kelompok I<br />dan III dengan nilai D 2 = 108.587. Penyumbang terbesar terjadinya<br />pengelompokan tersebut adalah karakter jumlah bekas daun.<br />Kata kunci : Pinang, Areca catechu L., populasi, jarak genetik, Sulawesi<br />Utara<br />ABSTRACT<br />Genetic diversity of seven arecanut (Areca catechu L.)<br />accessions from Sumatera Island<br />Genetic divergence analysis has been done on seven arecanut<br />(Areca catechu L.) populations, i.e, Sumut-1, Sumut-2, Sumbar-1,<br />Sumbar-2, Sumbar-3, Bengkulu-1, and Bengkulu-2 explorated in 1994 and<br />had been collected in Kayuwatu Experimental Garden, North Sulawesi.<br />The purpose of the analysis was to know how far the genetic distance<br />among the seven accessions of the arecanut. The analysis used D 2 statistics<br />of Mahalanobis, while to cluster the population used Tocher Method by<br />Rao. The result showed that there are four groups among the seven<br />accessions of arecanut. Group I consisted of Sumbar-1 and Sumut-1, group<br />II consisted of Sumbar-3, Sumut-2, and Bengkulu-1, and both of group III<br />and group IV consisted of one accession, namely Sumbar-2 and Bengkulu-<br />2 respectively. The largest genetic distance occurred between group I and<br />group II (D 2 = 1263.137) while the smallest genetic distance occurred<br />between group I and group III (D 2 = 108.587). Number of leaf scars was<br />the largest contribution of the grouping.<br />Key words : Arecanut, Areca catehcu L., population, genetic distance,<br />North Sulawesi

Genotypic characteristics of therrnoperon and genome of indigenous soybeanBradyrhizobiain cropping zones of China

2006 ◽  
Vol 52 (10) ◽  
pp. 968-976 ◽  
Author(s):  
Jiang Ke Yang ◽  
Wei Tao Zhang ◽  
Tian Ying Yuan ◽  
Jun Chu Zhou
Keyword(s):  
16S Rrna ◽  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
23S Rrna ◽  
Group Iii ◽  
The North ◽  
Group I ◽  
Genotypic Characteristics ◽  
Reference Strains

Four genetic assays, 16S rRNA restriction fragment length polymorphism (RFLP), 16S rRNA sequencing, 16S–23S rRNA intergenetic spacer (IGS) RFLP, and amplified fragment length polymorphism (AFLP), were conducted to determine the genotypic characteristics of 44 indigenous strains of Bradyrhizobium from soybean (Glycine max L.) cropping zones of China. The results generated from different assays showed that soybean bradyrhizobial isolates comprised four genomic groups. Group I was composed of strains mainly isolated from the North and Northeast plains of China. All four assays confirmed this group as phylogenetically divergent from all the reference strains. Strains of the group may represent a new species. Strains in Group II isolated from a variety of geographic regions were ascribed to B. liaoningense. Strains in Group III, mainly isolated from Central and East China, were closely related to the reference strains of B. japonicum. Strains in Group IV belonged to B. elkanii.Key words: soybean bradyrhizobia, 16S rRNA RFLP, 16S–23S IGS RFLP, AFLP.

scholarly journals Genetic Diversity and Population Structure of Dendrobium Nobile in Southwest of China Based On Genotyping-by-Sequencing

2021 ◽  
Author(s):  
Tao He ◽  
Changrong Ye ◽  
Qin Zeng ◽  
Xiaoli Fan ◽  
Tianfang Huang
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Population Variation ◽  
Quality Data ◽  
Group Method ◽  
Dendrobium Nobile ◽  
Group Iii ◽  
Group I ◽  
Quality Value

Abstract Dendrobium nobile Lindl. is one of the most important Orchid plants worldwide. The genotype-by-sequencing (GBS) method has now been widely used to access genetic diversity because of its high-throughput and cost-effective in molecular markers. The goal of this study was to employ the GBS technique for diversity evaluation of D. nobile and determine genetic differences between populations. A total of 129 accessions of D. nobile collected originally between 2019 and 2020 from 10 imitation-wild cultivated populations growing in Sichuan, Guizhou and Yunnan of southwestern China were sequenced, a total of 135G clean reads and a total of 836,786 SNPs of high quality data was yielded and were used for final analysis of genetic diversity and population structure. The quality value 20(Q20) ≥ 92.61%, the quality value 30(Q30) ≥ 82.38%. The GC contents distributed between 37.58% and 38.82%. It was also found that more transitions than transversions, and the ratio of transition/transversion varied from 1.804 to 1.911. By the methods of STRUCTURE, the most appropriate number was found to be k=3, all accessions of D. nobile were classified into three groups, excepts for 14 accessions belonging to admixed group. Phylogenetic tree and principal component analysis (PCA) were consistent with the result. The first two principal components explained a total of 23.25% of the variation by PCA. The genetic diversity of ML population showed the lower genetic diversity as indicated by the effective number of alleles (Ne) = 1.287, polymorphism information content (PIC) = 0.141, and Shannon's information index (I) = 0.205, while WT population showed slightly higher genetic diversity by the Ne =1.512, PIC =0.256, and I =0.360. ML population and other nine populations (FB, FM, FX, LJ, SJ, SP, WL, WT and XM) were the most divergent between them respectively owing to all pairwise Fst values above 0.25, while FM population and FX population were considered identical because the pairwise Fst value was 0.0 between the two populations. Correlation analysis showed that highly significant correlation was observed between genetic distance and actual geographical distance (r = 0.854, P < 0.0001), indicating that the genetic differentiation of the 10 D.nobile populations conformed to the geographical isolation model. Analysis of molecular variance (AMOVA) revealed that the genetic variation was greater within populations (87.8%) than among populations (12.2%). This confirmed that intra-population variation was the main source of genetic variation in 10 D. nobile populations. The results also showed that Nm = 1.799 > 1, indicating that there was gene exchange between different populations. Analysis of unweighted pair-group method with arithmetic mean (UPGMA) suggested that the 10 populations were classified into three groups (Group I, Group II and Group III), Group III could be further divided into two subgroups (Group IIIa and Group IIIb). The results will not only provide valuable information for the level of genetic diversity of D.nobile growing in southwestern of China but also help for formulation of strategies for resource protection and utilization. Moreover, GBS appears as an efficient tool to detect intra-population variation.

Controls on groundwater nitrogen contributions from on-site wastewater systems in coastal North Carolina

2010 ◽  
Vol 62 (6) ◽  
pp. 1448-1455 ◽  
Author(s):  
C. P. Humphrey ◽  
M. A. O'Driscoll ◽  
M. A. Zarate
Keyword(s):  
North Carolina ◽  
Inorganic Nitrogen ◽  
Separation Distance ◽  
Dissolved Inorganic Nitrogen ◽  
Group Iii ◽  
Soil Group ◽  
Group I ◽  
Wastewater Systems ◽  
Groundwater Nitrogen ◽  
Soil Groups

The goal of this study was to evaluate the influence of soil type and separation distance to water table on dissolved inorganic nitrogen concentrations in groundwater adjacent to on-site wastewater systems. Groundwater nitrogen species (NO3−-N and NH4+-N) and groundwater levels adjacent to 16 on-site systems in three different soil groups (group I- sand, group II- coarse loams and group III -sandy clay loams) were monitored for 15 months (January 2007–March 2008) in coastal North Carolina. On-site systems in soil group I had the highest concentrations of dissolved inorganic nitrogen (median of 18.9 mg/L) in groundwater, and most frequently (mean 61%) exceeded 10 mg/L, followed by systems in soil group II (11.0 mg/L, 50%) and soil group III (2.6 mg/L, 9%), respectively. Groundwater NH4+-N concentrations near on-site systems in soil groups I and II that maintained a 60 + cm separation to the seasonal high water table were 4 mg/L lower in relation to systems that had &lt;60 cm separation, but median NO3−-N concentrations were 6.5 mg/L higher. On-site systems in group I and II soils are prone to groundwater nitrogen loading with separation distance often controlling the nitrogen speciation in groundwater near on-site systems.

Presence of Classical Enterotoxin Genes, agr Typing, Antimicrobial Resistance, and Genetic Diversity of Staphylococcus aureus from Milk of Cows with Mastitis in Southern Brazil

2018 ◽  
Vol 81 (5) ◽  
pp. 738-742 ◽  
Author(s):  
ISABELA S. KRONING ◽  
MARIANA A. IGLESIAS ◽  
KARLA S. MENDONÇA ◽  
GRACIELA V. LOPES ◽  
WLADIMIR P. SILVA
Keyword(s):  
Genetic Diversity ◽  
Antimicrobial Resistance ◽  
Antimicrobial Agents ◽  
Bovine Mastitis ◽  
Disease Outbreaks ◽  
Southern Brazil ◽  
Group Iii ◽  
Distinct Area ◽  
Group I ◽  
Enterotoxin Genes

ABSTRACTStaphylococcus aureusis a common causative agent of bovine mastitis in dairy cows and commonly associated with foodborne disease outbreaks. The aim of this study was to evaluate the presence of enterotoxin genes, agr typing, antimicrobial resistance, and genetic diversity of S. aureus isolated from milk of cows with mastitis in dairy farms from southern Brazil. Results showed that 7 (22.6%) of 31 S. aureus isolates were positive for enterotoxin genes. Specifically, the genes encoding for enterotoxins A (n = 4), C (n = 2), and B (n = 1) were detected. Isolates belonging to the agr group III (10 of 31, 32.2%) and agr group I (7 of 31, 22.5%) were the most common. To our knowledge, this is the first report of both agr I and III in the same S. aureus isolate from milk of cows with bovine mastitis. The antimicrobial resistance test showed that 54% of the isolates were multiresistant to antimicrobial agents. The macrorestriction analysis produced 16 different major SmaI pulsed-field gel electrophoresis patterns, with up to two subpatterns. Moreover, the presence of some S. aureus clones in a distinct area was observed. Although this study characterized a limited number of S. aureus isolates, the presence of classical enterotoxin genes and resistance to multiple antimicrobial agents reinforces the importance of this microorganism to animal and human health. In addition, similar genetic profiles have been identified in distinct geographic areas, suggesting clonal dissemination of S. aureus in dairy herds from southern Brazil.

Virulence of a soil inhabiting fungus, Ophiosphaerella korrae, to rice

2020 ◽  
Author(s):  
Keisuke Tomioka ◽  
Kenji Nagata ◽  
Masahiro Chiba ◽  
Kobayashi Hidekazu ◽  
Naoyuki Ishikawa ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Annual Meeting ◽  
Bread Wheat ◽  
Kentucky Bluegrass ◽  
Rice Cultivar ◽  
Growth Delay ◽  
Fungal Strains ◽  
Spring Dead Spot ◽  
Seed Growth ◽  
Ophiosphaerella Korrae

&lt;p&gt;A soil inhabiting fungus, &lt;em&gt;Ophiosphaerella korrae&lt;/em&gt; (J. Walker &amp; A.M. Sm. bis) Shoemaker &amp; C.E. Babc. has been confirmed to be pathogenic to barley, durum wheat and bread wheat of the major crops (Hong et al., 2018; Tomioka et al., 2019ab). Foliage and spikes of the affected plants early blight with root rot and ripening disorder. In this study, we revealed virulence of the fungus to rice, which is also one of the major crops. When a rice cultivar (cv. Norin No. 22) was grown in pots in artificial climate chambers after being sowed with culture discs (6 mm in diameter) of the fungus (strains MAFF150117 and MAFF150118 from bread wheat and durum wheat, respectively) on synthetic nutrient agar (SNA) (1 disc per seed), growth delay and early foliage blight (including ripening disorder) with rotting of roots and stem bases occurred. Defect rates were 22% and 84% for the plants inoculated with strains MAFF150117 and MAFF150118, respectively. Control plants simultaneously treated with aseptic SNA discs had no symptom. The fungal strains were consistently isolated from all the inoculated plants, but not from healthy controls, demonstrating that the fungal strains were virulent to rice. Additionally, a decrease tendency of grain yield without symptom on foliage and roots was detected on a rice cultivar (cv. Koshihikari that is cv. Norin No. 1 &amp;#215; cv. Norin No. 22) inoculated with strain MAFF150117 in another pot experiment. &lt;em&gt;Ophiosphaerella korrae&lt;/em&gt; is also known as a pathogen causing spring dead spot or necrotic ring spot of Bermudagrass (Wetzel et al., 1999ab; Camara et al., 2000; Iriarte et al., 2004; Gullino et al., 2007; Perry et al., 2010; Sasaki et al., 2010), Kentucky bluegrass (Wetzel et al., 1999a; Camara et al., 2000, 2001; Hayakawa et al., 2004; Wong et al., 2015), Louisiana grass (Wetzel et al., 1999a; Camara et al., 2000) and Zoysiagrass (Hayakawa et al., 2004; Tredway and Butler, 2007). We will investigate varietal difference against &lt;em&gt;O. korrae&lt;/em&gt; as well as the fungal emergent ecology in the future.&lt;/p&gt;&lt;p&gt;[References] Camara et al. (2000) Mycologia 92:317-325 Camara et al. (2001) Mycol Res 105:41-56 Gullino et al. (2007) Pl Dis 91:1200 Hayakawa et al. (2004) J Jpn Soc Turf Sci 33 (Supplement 1):24-25 Hong et al. (2018) Pl Dis 103(1):158 Iriarte et al. (2004) Pl Dis 88:1341-1346 Perry et al. (2010) Mycopathologia 169:395-402 Sasaki et al. (2010) Jpn J Phytopathol 76(3):158 Tomioka et al. (2019a) Abstracts of papers presented at the 44th annual meeting of the pesticide science society of Japan, p 82 Tomioka et al. (2019b) Abstracts of papers presented at the 63th annual meeting of the mycological society of Japan, p 64 Tredway and Butler (2007) Pl Dis 91:1684 Wetzel et al. (1999a) Mycol Res 103:981-989 Wetzel et al. (1999b) Pl Dis 83:1160-1166 Wong et al. (2015) Pl Pathol 44:545-555&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals AFLP Analysis of Phytophthora cactorum Isolates from Strawberry and Other Hosts: Implications for Identifying the Primary Source of Inoculum

Plant Disease ◽  
2004 ◽  
Vol 88 (7) ◽  
pp. 714-720 ◽  
Author(s):  
H. Huang ◽  
S. N. Jeffers ◽  
D. R. Layne ◽  
G. Schnabel
Keyword(s):  
Genetic Diversity ◽  
North Carolina ◽  
South Carolina ◽  
Fragment Length Polymorphism ◽  
Primary Source ◽  
Crown Rot ◽  
Aflp Analysis ◽  
Phytophthora Cactorum ◽  
Pair Group ◽  
Geographical Populations

Forty-seven isolates of Phytophthora cactorum from North America and Germany were subjected to amplified fragment length polymorphism (AFLP) analysis to investigate genetic diversity among isolates and geographical populations; 42 isolates were recovered from cultivated strawberry plants (Fragaria × ananassa), and five isolates had been recovered from plants in four other genera (Syringa, Abies, Malus, and Panax). From all isolates evaluated, 226 out of 264 markers (85.6%) were polymorphic and provided 42 unique AFLP profiles. The genetic diversity among isolates of P. cactorum from strawberry was greater than that among isolates from the other hosts. Isolates collected during recent crown rot epidemics in strawberry fields in South Carolina were genetically diverse and scattered among isolates from other geographical areas in an unweighted pair-group mean analysis (UPGMA) dendrogram. Isolates collected during recent crown rot epidemics in North Carolina also were genetically diverse, but most isolates clustered with isolates collected in 1997 from Florida strawberry fields. These data suggest that recent outbreaks of Phytophthora crown rot in the southeastern United States resulted from use of transplants already infected or infested with P. cactorum rather than from endemic populations of this pathogen, which would affect recommendations for disease management.

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