scholarly journals Molecular Markers Dispute the Existence of the Afro-Andean Group of the Bean Angular Leaf Spot Pathogen, Phaeoisariopsis griseola

2002 ◽  
Vol 92 (6) ◽  
pp. 580-589 ◽  
Author(s):  
George S. Mahuku ◽  
María Antonia Henríquez ◽  
Jaime Munõz ◽  
Robin A. Buruchara
Keyword(s):  
Genetic Differentiation ◽  
Leaf Spot ◽  
Multiple Correspondence Analysis ◽  
Gene Diversity ◽  
Random Amplified Polymorphic Dna ◽  
Point Mutations ◽  
Angular Leaf Spot ◽  
Gene Pools ◽  
Phaeoisariopsis Griseola ◽  
Intergenic Spacer Region

Coevolution of the angular leaf spot pathogen, Phaeoisariopsis griseola, with its common bean host has been demonstrated, and P. griseola isolates have been divided into Andean and Mesoamerican groups that correspond to defined bean gene pools. Recent characterization of P. griseola isolates from Africa has identified a group of isolates classified as Andean using random amplified polymorphic DNA (RAPD), but which are able to infect some Mesoamerican differential varieties. These isolates, designated Afro-Andean, have been identified only in Africa. Random amplified microsatellites, RAPD, and restriction digestion of amplified ribosomal intergenic spacer region were used to elucidate the relationships among the Afro-Andean, Andean, and Mesoamerican groups of P. griseola. Cluster and multiple correspondence analysis of molecular data separated isolates into Andean and Meso-american groups, and the Afro-Andean isolates clustered with Andean isolates. Analysis of molecular variance ascribed 2.8% of the total genetic variation to differences between Afro-Andean and Andean isolates from Africa. Gene diversity analysis revealed no genetic differentiation (GST = 0.004) between Afro-Andean and Andean isolates from Africa. However, significant levels of genetic differentiation (GST = 0.39) were observed between Afro-Andean or Andean isolates from Africa and Andean isolates from Latin America, revealing significant geographical differentiation within the Andean lineage. Results from this study showed that Afro-Andean isolates do not constitute a new P. griseola group and do not represent long-term evolution of the pathogen genome, but rather are likely the consequents of point mutations in genes for virulence. This finding has significant implications in the deployment of resistant bean genotypes.

scholarly journals First Report of Angular Leaf Spot Caused by Phaeoisariopsis griseola on Phaseolus coccineus in Argentina

Plant Disease ◽  
2006 ◽  
Vol 90 (2) ◽  
pp. 248-248 ◽  
Author(s):  
S. A. Stenglein ◽  
P. A. Balatti ◽  
O. N. Vizgarra ◽  
L. D. Ploper
Keyword(s):  
Common Bean ◽  
Leaf Spot ◽  
Random Amplified Polymorphic Dna ◽  
Culture Collection ◽  
Angular Leaf Spot ◽  
Phaeoisariopsis Griseola ◽  
First Report ◽  
Runner Bean ◽  
Applied Microbiology

Angular leaf spot (ALS), caused by Phaeoisariopsis griseola (Sacc.) Ferraris, is one of the most destructive and widespread problems of common bean (Phaseolus vulgaris L.) in Tucumán and other northwestern provinces of Argentina (4). Symptoms similar to those of ALS were observed during April 2005 on most plants of runner bean (P. coccineus L.) in an 80-ha field in Tafí del Valle, Tucumán (2,000 m above sea level). Leaf lesions were brown to gray, irregular to angular to circular, and 0.5 to 1 cm in diameter. Lesions on pods were oval to circular with reddish brown centers surrounded by darker brown borders. Conidia in vivo were curved cylindrical to obclavate with one to five septa and measured 25 to 60 × 3.5 to 7 μm. The conidiophores were 100 to 250 μm high and clustered together to form synnemata measuring 20 to 50 μm in diameter. The pathogen was isolated by placing conidia from diseased leaves onto potato dextrose agar (PDA) at pH 6. Colonies measuring 2 to 3 mm in diameter composed of dense, dark olive mycelium developed after incubation in the dark at 24 ± 2°C for 3 to 4 days. Pathogenicity of the isolate was tested with conidia obtained from the second subculture of 14-day-old colonies on PDA. Conidial suspensions of 2 × 104 conidia per ml were sprayed onto the upper and lower surfaces of the first trifoliolate leaves of six runner bean plants, 18 days after planting. Inoculated and control plants (sprayed with distilled water) were placed in a growth chamber with a 12-h photoperiod at 24 ± 2°C and 95 to 100% relative humidity and 48 h later moved to the greenhouse. Disease symptoms were evaluated 18 days after inoculation. While control plants were healthy, all inoculated plants showed symptoms similar to those observed in the field. The fungus that was consistently reisolated from lesions in the inoculated plants was identified as Phaeoisariopsis griseola on the basis of fungal morphology (1), symptoms produced on leaves (3), and random amplified polymorphic DNA data with primer 5′-CAATCGCCGT-3′ (2). Runner bean is a new crop in Tafí del Valle, which is a geographically isolated area. In a period of only 2 years, the area cultivated with beans increased approximately five-fold. Because of this, the presence of a pathogen like Phaeoisariopsis griseola, which causes considerable reduction in yield in most common bean-producing areas of Argentina, is of concern. To our knowledge, this is the first report of ALS occurring on P. coccineus in Argentina. This report may prompt the inclusion of regular testing of seeds for ALS in P. coccineus-production areas. A voucher culture has been deposited in the LPSC (Culture collection of the La Plata Spegazzini Institute) No. 844. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) P. Guzmán et al. Plant Dis. 83:37, 1999. (3) A. W. Saettler. Pages 15–16 in: Compendium of Bean Diseases. R. Hall, ed, The American Phytopathological Society, St. Paul, 1991. (4) S. A. Stenglein et al. Pages 209–243 in: Advances in Applied Microbiology, Vol. 52. A. I. Laskin et al., eds, Academic Press, San Diego, 2003.

scholarly journals Identification of Phaeoisariopsis griseola pathotypes from five States in Brazil

2002 ◽  
Vol 27 (1) ◽  
pp. 78-81 ◽  
Author(s):  
ALOISIO SARTORATO
Keyword(s):  
Phaseolus Vulgaris ◽  
Common Bean ◽  
Resistance Genes ◽  
Leaf Spot ◽  
Angular Leaf Spot ◽  
Phaeoisariopsis Griseola ◽  
Moist Chamber ◽  
Differential Cultivars ◽  
Pathogenic Variability ◽  
Resistant Genotypes

Due to the increased importance of angular leaf spot of common bean (Phaseolus vulgaris) in Brazil, monitoring the pathogenic variability of its causal agent (Phaeoisariopsis griseola) is the best strategy for a breeding program aimed at developing resistant genotypes. Fifty one isolates of P. griseola collected in five Brazilian States were tested on a set of 12 international differential cultivars in the greenhouse. When inoculated plants showed symptoms but no sporulation was observed, they were transferred to a moist chamber for approximately 20-24 h. After this period of time, if no sporulation was observed, the plants were considered resistant; otherwise, they were considered susceptible. From the fifty-one tested isolates, seven different pathotypes were identified. No Andean pathotypes were identified; consequently, all isolates were classified as Middle American pathotypes. Pathotype 63-31 was the most widespread. Pathotype 63-63 overcame resistance genes present in all differential cultivars and also the resistance gene(s) present in the cultivar AND 277. This fact has important implications for breeding angular leaf spot resistance in beans, and suggests that searching for new resistance genes to angular leaf spot must be pursued.

scholarly journals Development of microsatellite markers for the  characterisation of Phaeoisariopsis griseola (bean angular leaf spot agent) populations in Central  America

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. S35-S37
Author(s):  
J.P. Busogoro ◽  
O. Duterme ◽  
P. Lepoivre
Keyword(s):  
Leaf Spot ◽  
Large Scale ◽  
Genomic Library ◽  
Angular Leaf Spot ◽  
Size Analysis ◽  
Phaeoisariopsis Griseola ◽  
Apparent Contradiction ◽  
Large Scale Analysis ◽  
Sexual Recombination ◽  
Pathogen Populations

Although several researches revealed an important diversity within Phaeoisariopsis griseola, the bean angular leaf spot (ALS) agent, no sexual recombination was already detected for this fungus. That apparent contradiction gave rise to the interest to develop codominant markers in order of a more precise analysis of the pathogen populations. Microsatellites were expected to allow characterising P. griseola populations in terms of allele frequencies. A genomic library was constructed by ligating DNA fragments, previously prepared by enzymatic restriction of total DNA of two pathogen strains, into a pZERO plasmid. After transformation of TOP 10F’ strains of E. coli with the recombinant plasmid, a total of 448 colonies were selected for zeocin resistance. The probe mixture [(GT)<sub>15</sub>, (GA)<sub>15</sub>, (GATA)<sub>8</sub>, (GTG)<sub>10</sub>], previously labelled with <sup>32</sup>P, was used to screen the genomic library for the presence of microsatellite sequences. The vector DNA was then extracted from the positive colonies and sequenced. Based on the sequences, a first group of 10 microsatellite loci was identified and the corresponding primers designed. A size analysis using an ALF express system exhibited 3 polymophic microsatellites among a total of 4 loci already considered. The identification of other polymorphic microsatellites is continuing before a large scale analysis of our pathogen collection by using this new molecular tool developed for P. griseola.

scholarly journals Genetic Structure of Cronartium ribicola Populations in Eastern Canada

1999 ◽  
Vol 89 (10) ◽  
pp. 915-919 ◽  
Author(s):  
K. Et-touil ◽  
L. Bernier ◽  
J. Beaulieu ◽  
J. A. Bérubé ◽  
A. Hopkin ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Genetic Differentiation ◽  
Distribution Systems ◽  
Gene Diversity ◽  
Isolation By Distance ◽  
Random Amplified Polymorphic Dna ◽  
Cronartium Ribicola ◽  
Eastern Canada ◽  
Long Distance ◽  
Evolutionary Forces

The genetic structure of populations of Cronartium ribicola was studied by sampling nine populations from five provinces in eastern Canada and generating DNA profiles using nine random amplified polymorphic DNA markers. Most of the total gene diversity (Ht = 0.386) was present within populations (Hw = 0.370), resulting in a low level of genetic differentiation among populations in northeastern North America (Fst = 0.062). A hierarchical analysis of genetic structure using an analysis of molecular variance (AMOVA) revealed no statistically significant genetic differentiation among provinces or among regions. Yet, genetic differentiation among populations within regions or provinces was small (AMOVA φst = 0.078) but statistically significant (P < 0.001) and was several orders of magnitude larger than differentiation among provinces. This is consistent with a scenario of subpopulations within a metapopulation, in which random drift following migration and new colonization are major evolutionary forces. A phenetic analysis using genetic distances revealed no apparent correlation between genetic distance and the province of origin of the populations. The hypothesis of isolation-by-distance in the eastern populations of C. ribicola was rejected by computing Mantel correlation coefficients between genetic and geographic distance matrices (P > 0.05). These results show that eastern Canadian provinces are part of the same white pine blister rust epidemiological unit. Nursery distribution systems are controlled provincially, with virtually no seedling movement among provinces; therefore, infected nursery material may not play an important role in the dissemination of this disease. Long-distance spore dispersal across provincial boundaries appears to be an epidemiologically important factor for this pathogen.

Integrated Management of Angular Leaf Spot (Phaeoisariopsis griseola (Sacc.) Ferr.) on Snap Beans in Ontario

2005 ◽  
Vol 6 (1) ◽  
pp. 2 ◽  
Author(s):  
Michael J. Celetti ◽  
Melody S. Melzer ◽  
Greg J. Boland
Keyword(s):  
Disease Management ◽  
Leaf Spot ◽  
Management Strategy ◽  
Gold Rush ◽  
Angular Leaf Spot ◽  
Phaeoisariopsis Griseola ◽  
Snap Bean ◽  
Snap Beans ◽  
Disease Management Strategy ◽  
Growth Room

Angular leaf spot (ALS) caused by the fungus Phaeoisariopsis griseola (Sacc.) Ferr. was first observed and confirmed on snap beans growing in three commercial fields in southern Ontario during the 2000 growing season. The potential impact of this disease on the bean industry in Ontario is not known but this disease is severe in many other regions. The objective of this study was to develop a disease management strategy for ALS in Ontario by investigating the survival of P. griseola in Ontario, and assessing the influence of bean varieties and fungicides on disease development. P. griseola survived at least one winter on crop debris in Ontario and survived better on the soil surface in comparison to burial in soil at depths of 5 or 25 cm. Fifteen snap bean varieties were compared for susceptibility to ALS in a growth room, and nine varieties were compared in a naturally-infested field from 2001-2003. Most varieties reacted similarly to P. griseola in both environments. For example, the varieties Carlo, Storm, and Bush Blue Lake 47 were least susceptible whereas Gold Rush was most susceptible in field and growth room experiments. Boscalid, pyraclostrobin, pyramethanil, vinclozolin, and thiophanate-methyl were tested for effectiveness in managing ALS under field conditions. Overall, pyraclostrobin was most effective. Results indicate that an effective disease management strategy for ALS in snap bean in Ontario should include burying infested plant debris through deep plowing, crop rotation for two years, growing the least susceptible varieties, and applying a registered effective fungicide. Accepted for publication 13 October 2005. Published 29 November 2005.

An analysis of genetic differentiation and geographical variation of spinach germplasm using SSR markers

2013 ◽  
Vol 12 (2) ◽  
pp. 185-190 ◽  
Author(s):  
Kouhei Kuwahara ◽  
Reimi Suzuki ◽  
Yusuke Ito ◽  
Tetsuo Mikami ◽  
Yasuyuki Onodera
Keyword(s):  
Genetic Differentiation ◽  
Ssr Markers ◽  
Gene Diversity ◽  
East Asian ◽  
Gene Pools ◽  
Hierarchical Analysis ◽  
A Value ◽  
Geographical Regions ◽  
The Usa ◽  
Simple Sequence

To assess the genetic diversity of spinach germplasm, 250 individuals of 50 accessions collected from geographically diverse regions (West Asia, East Asia, Japan, Europe and the USA) were analysed using simple sequence repeat (SSR) markers. A total of 39 polymorphic alleles were identified, with an average of 6.5 alleles per locus for six loci. The overall gene diversity (0.62) in the entire set of individuals suggests that the germplasm has high genetic variability. The West Asian accessions showed the highest gene diversity, with a value of 0.57, followed by the East Asian accessions. These results help confirm the notion that spinach originated from West Asia. Hierarchical analysis of molecular variance revealed significant genetic differentiation among the geographical regions, which accounts for 26% of the total variation detected. Furthermore, pairwise Φst values indicate low genetic differentiation between the East Asian and Japanese germplasm accessions, both of which showed high genetic differentiation from the European accessions. The differentiation between the East Asian and European gene pools may be attributed to the founder effect associated with crop dissemination, as well as to the selection and genetic drift that occurred during the breeding process.

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