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Majid R Foolad - One of the best experts on this subject based on the ideXlab platform.
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genetics genomics and breeding of late Blight and Early Blight resistance in tomato
Critical Reviews in Plant Sciences, 2008Co-Authors: Majid R Foolad, Heather L Merk, Hamid AshrafiAbstract:Late Blight (LB), caused by the oomycete Phytophthora infestans, and Early Blight (EB), caused by the fungi Alternaria solani and A. tomatophila, are two common and destructive foliar diseases of the cultivated tomato (Solanum lycopersicum) and potato (Solanum tuberosum) in the United States and elsewhere in the world. While LB can infect and devastate tomato plants at any developmental stages, EB infection is usually associated with plant physiological maturity and fruit load where older senescing plants exhibit greater susceptibility and a heavy fruit set enhances the disease. At present, cultural practices and heavy use of fungicides are the most common measures for controlling LB and EB. Genetic resources for resistance have been identified for both diseases, largely within the tomato wild species, in particular the red-fruited species S. pimpinellifolium and the green-fruited species S. habrochaites. A few race-specific major resistance genes (e.g., Ph-1, Ph-2 and Ph-3) and several race-nonspecific r...
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mapping qtls conferring Early Blight alternaria solani resistance in a lycopersicon esculentum l hirsutum cross by selective genotyping
Molecular Breeding, 2003Co-Authors: Liping Zhang, G Y Lin, D Ninoliu, Majid R FooladAbstract:Most commercial cultivars of tomato, Lycopersicon esculentum Mill., are susceptible to Early Blight (EB), a devastating fungal (Alternaria solani Sorauer) disease of tomato in the U.S. and elsewhere in the world. Currently, sanitation, long crop rotation, and routine application of fungicides are the most common disease control measures. Although no source of genetic resistance is known within the cultivated species of tomato, resistant resources have been identified within related wild species. The purpose of this study was to identify and validate quantitative trait loci (QTLs) conferring EB resistance in an accession (PI126445) of the tomato wild species L. hirsutum Humb. and Bonpl. by using a selective genotyping approach. A total of 820 BC1 plants of a cross between an EB susceptible tomato breeding line (NC84173; maternal and recurrent parent) and PI126445 were grown in a greenhouse. During late seedling stage, plants were inoculated with mixed isolates of A. solani and subsequently evaluated for EB symptoms. The most resistant (75 plants = 9.1%) and most susceptible (80 = 9.8%) plants were selected and subsequently transplanted into a field where natural infestation of EB was severe. Plants were grown to maturity and evaluated for final disease severity. From among the 75 resistant plants, 46 (5.6% of the total) that exhibited the highest resistance, and from among the 80 susceptible plants, 30 (3.7% of the total) that exhibited the highest susceptibility, were selected. The 76 selected plants, representing the two extreme tails of the response distribution, were genotyped for 145 restriction fragment length polymorphism (RFLP) markers and 34 resistance gene analogs (RGAs). A genetic linkage map, spanning approximately 1298 cM of the 12 tomato chromosomes with an average marker distance of 7.3 cM, was constructed. A trait-based marker analysis (TBA), which measures differences in marker allele frequencies between extreme tails of a population, detected seven QTLs for EB resistance, one on each of chromosomes 3, 4, 5, 6, 8, 10 and 11. Of these, all but the QTL on chromosome 3 were contributed from the resistant wild parent, PI126445. The standardized effects of the QTLs ranged from 0.45 to 0.81 phenotypic standard deviations. Four of the seven QTLs were previously identified in a study where different populations and mapping strategy were used. The high level of correspondence between the two studies indicated the reliability of the detected QTLs and their potential use for marker-assisted breeding for EB resistance. The location of several RGAs coincided with locations of EB QTLs or known tomato resistance genes (R genes), suggesting that these RGAs could be associated with disease resistance. Furthermore, similar to that for many R gene families, several RGA loci were identified in clusters, suggesting their potential evolutionary relationship with R genes.
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identification of qtls for Early Blight alternaria solani resistance in tomato using backcross populations of a lycopersicon esculentum x l hirsutum cross
Theoretical and Applied Genetics, 2002Co-Authors: Majid R Foolad, Liping Zhang, D Ninoliu, A Khan, G Y LinAbstract:Most commercial cultivars of tomato, Lycopersicon esculentum Mill., are susceptible to Early Blight (EB), a devastating fungal (Alternaria solani Sorauer) disease of tomato in the northern and eastern parts of the U.S. and elsewhere in the world. The disease causes plant defoliation, which reduces yield and fruit quality, and contributes to significant crop loss. Sources of resistance have been identified within related wild species of tomato. The purpose of this study was to identify and validate quantitative trait loci (QTLs) for EB resistance in backcross populations of a cross between a susceptible tomato breeding line (NC84173; maternal and recurrent parent) and a resistant Lycopersicon hirsutum Humb. and Bonpl. accession (PI126445). Sixteen hundred BC1 plants were grown to maturity in a field in 1998. Plants that were self-incompatible, indeterminant in growth habit, and/or extremely late in maturity, were discarded in order to eliminate confounding effects of these factors on disease evaluation, QTL mapping, and future breeding research. The remaining 145 plants (referred to as the BC1 population) were genotyped for 141 restriction fragment length polymorphism (RFLP) markers and 23 resistance gene analogs (RGAs), and a genetic linkage map was constructed. BC1 plants were evaluated for disease symptoms throughout the season, and the area under the disease progress curve (AUDPC) and the final percent defoliation (disease severity) were determined for each plant. BC1 plants were self-pollinated and produced BC1S1 seed. The BC1S1 population, consisting of 145 BC1S1 families, was grown and evaluated for disease symptoms in replicated field trials in two subsequent years (1999 and 2000) and AUDPC and/or final percent defoliation were determined for each family in each year. Two QTL mapping approaches, simple interval mapping (SIM) and composite interval mapping (CIM), were used to identify QTLs for EB resistance in the BC1 and BC1S1 populations. QTL results were highly consistent across generations, years and mapping approaches. Approximately ten significant QTLs (LOD ≥ 2.4, P ≤ 0.001) were identified (and validated) for EB resistance, with individual effects ranging from 8.4% to 25.9% and with combined effects of >57% of the total phenotypic variation. All QTLs had the positive alleles from the disease-resistant parent. The good agreement between results of the BC1 and 2 years of the BC1S1 generations indicated the stability of the identified QTLs and their potential usefulness for improving tomato EB resistance using marker-assisted selection (MAS). Further inspections using SIM and CIM indicated that six of the ten QTLs had independent additive effects and together could account for up to 56.4% of the total phenotypic variation. These complementary QTLs, which were identified in two generations and 3 years, should be the most useful QTLs for MAS and improvement of tomato EB resistance using PI126445 as a gene resource. Furthermore, the chromosomal locations of 10 of the 23 RGAs coincided with the locations of three QTLs, suggesting possible involvement of these RGAs with EB resistance and a potential for identifying and cloning genes which confer EB resistance in tomato.
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parent offspring correlation estimate of heritability for Early Blight resistance in tomato lycopersicon esculentum mill
Euphytica, 2002Co-Authors: Majid R Foolad, P Subbiah, G S GhangasAbstract:This study estimated the heritability (h2) of Early Blight (EB) resistance in filial progeny of a cross between a susceptible (`NC84173';mid-season maturity) and a resistant (`NC39E'; late-season maturity)tomato breeding lines. It addition, it examined the potential of identifying progeny with mid-season maturity and EB resistance. A total of 162F2 plants were grown under field conditions in 1998 and evaluated for disease symptoms three times during the season, and the area under the disease progress curve (AUDPC) and final percent defoliation (disease severity) were determined. The F2 plants were self-pollinated and F3 seeds produced. The 162 F3 progeny families, consisting of 20 plants per family, were grown in a replicated field trial in 1999 and evaluated for EB resistance (final percent defoliation) and plant maturity(days to 50% ripe fruit). The distributions of the final percent defoliation values in the F2 and F3 generations indicated that resistance from `NC39E' was quantitative in nature. Estimates of h2 for EB resistance, computed as the correlation coefficients between F3progeny family means and F2 individual plant values, ranged from0.65 to 0.71, indicating that EB resistance of `NC39E' was heritable. Across F3 families, a negative correlation (r = –0.46, p< 0.01) was observed between disease severity and earliness in maturity, indicating that plant maturity affected disease severity. However, several F3 families were identified with considerable EB resistance and mid-season maturity, indicating that resistance from `NC39E' might be useful for the development of commercially acceptable EB resistant tomato cultivars.
G Y Lin - One of the best experts on this subject based on the ideXlab platform.
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mapping qtls conferring Early Blight alternaria solani resistance in a lycopersicon esculentum l hirsutum cross by selective genotyping
Molecular Breeding, 2003Co-Authors: Liping Zhang, G Y Lin, D Ninoliu, Majid R FooladAbstract:Most commercial cultivars of tomato, Lycopersicon esculentum Mill., are susceptible to Early Blight (EB), a devastating fungal (Alternaria solani Sorauer) disease of tomato in the U.S. and elsewhere in the world. Currently, sanitation, long crop rotation, and routine application of fungicides are the most common disease control measures. Although no source of genetic resistance is known within the cultivated species of tomato, resistant resources have been identified within related wild species. The purpose of this study was to identify and validate quantitative trait loci (QTLs) conferring EB resistance in an accession (PI126445) of the tomato wild species L. hirsutum Humb. and Bonpl. by using a selective genotyping approach. A total of 820 BC1 plants of a cross between an EB susceptible tomato breeding line (NC84173; maternal and recurrent parent) and PI126445 were grown in a greenhouse. During late seedling stage, plants were inoculated with mixed isolates of A. solani and subsequently evaluated for EB symptoms. The most resistant (75 plants = 9.1%) and most susceptible (80 = 9.8%) plants were selected and subsequently transplanted into a field where natural infestation of EB was severe. Plants were grown to maturity and evaluated for final disease severity. From among the 75 resistant plants, 46 (5.6% of the total) that exhibited the highest resistance, and from among the 80 susceptible plants, 30 (3.7% of the total) that exhibited the highest susceptibility, were selected. The 76 selected plants, representing the two extreme tails of the response distribution, were genotyped for 145 restriction fragment length polymorphism (RFLP) markers and 34 resistance gene analogs (RGAs). A genetic linkage map, spanning approximately 1298 cM of the 12 tomato chromosomes with an average marker distance of 7.3 cM, was constructed. A trait-based marker analysis (TBA), which measures differences in marker allele frequencies between extreme tails of a population, detected seven QTLs for EB resistance, one on each of chromosomes 3, 4, 5, 6, 8, 10 and 11. Of these, all but the QTL on chromosome 3 were contributed from the resistant wild parent, PI126445. The standardized effects of the QTLs ranged from 0.45 to 0.81 phenotypic standard deviations. Four of the seven QTLs were previously identified in a study where different populations and mapping strategy were used. The high level of correspondence between the two studies indicated the reliability of the detected QTLs and their potential use for marker-assisted breeding for EB resistance. The location of several RGAs coincided with locations of EB QTLs or known tomato resistance genes (R genes), suggesting that these RGAs could be associated with disease resistance. Furthermore, similar to that for many R gene families, several RGA loci were identified in clusters, suggesting their potential evolutionary relationship with R genes.
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identification of qtls for Early Blight alternaria solani resistance in tomato using backcross populations of a lycopersicon esculentum x l hirsutum cross
Theoretical and Applied Genetics, 2002Co-Authors: Majid R Foolad, Liping Zhang, D Ninoliu, A Khan, G Y LinAbstract:Most commercial cultivars of tomato, Lycopersicon esculentum Mill., are susceptible to Early Blight (EB), a devastating fungal (Alternaria solani Sorauer) disease of tomato in the northern and eastern parts of the U.S. and elsewhere in the world. The disease causes plant defoliation, which reduces yield and fruit quality, and contributes to significant crop loss. Sources of resistance have been identified within related wild species of tomato. The purpose of this study was to identify and validate quantitative trait loci (QTLs) for EB resistance in backcross populations of a cross between a susceptible tomato breeding line (NC84173; maternal and recurrent parent) and a resistant Lycopersicon hirsutum Humb. and Bonpl. accession (PI126445). Sixteen hundred BC1 plants were grown to maturity in a field in 1998. Plants that were self-incompatible, indeterminant in growth habit, and/or extremely late in maturity, were discarded in order to eliminate confounding effects of these factors on disease evaluation, QTL mapping, and future breeding research. The remaining 145 plants (referred to as the BC1 population) were genotyped for 141 restriction fragment length polymorphism (RFLP) markers and 23 resistance gene analogs (RGAs), and a genetic linkage map was constructed. BC1 plants were evaluated for disease symptoms throughout the season, and the area under the disease progress curve (AUDPC) and the final percent defoliation (disease severity) were determined for each plant. BC1 plants were self-pollinated and produced BC1S1 seed. The BC1S1 population, consisting of 145 BC1S1 families, was grown and evaluated for disease symptoms in replicated field trials in two subsequent years (1999 and 2000) and AUDPC and/or final percent defoliation were determined for each family in each year. Two QTL mapping approaches, simple interval mapping (SIM) and composite interval mapping (CIM), were used to identify QTLs for EB resistance in the BC1 and BC1S1 populations. QTL results were highly consistent across generations, years and mapping approaches. Approximately ten significant QTLs (LOD ≥ 2.4, P ≤ 0.001) were identified (and validated) for EB resistance, with individual effects ranging from 8.4% to 25.9% and with combined effects of >57% of the total phenotypic variation. All QTLs had the positive alleles from the disease-resistant parent. The good agreement between results of the BC1 and 2 years of the BC1S1 generations indicated the stability of the identified QTLs and their potential usefulness for improving tomato EB resistance using marker-assisted selection (MAS). Further inspections using SIM and CIM indicated that six of the ten QTLs had independent additive effects and together could account for up to 56.4% of the total phenotypic variation. These complementary QTLs, which were identified in two generations and 3 years, should be the most useful QTLs for MAS and improvement of tomato EB resistance using PI126445 as a gene resource. Furthermore, the chromosomal locations of 10 of the 23 RGAs coincided with the locations of three QTLs, suggesting possible involvement of these RGAs with EB resistance and a potential for identifying and cloning genes which confer EB resistance in tomato.
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comparison of field greenhouse and detached leaflet evaluations of tomato germ plasm for Early Blight resistance
Plant Disease, 2000Co-Authors: M R Foolad, N Ntahimpera, B J Christ, G Y LinAbstract:ABSTRACT Twenty-nine tomato genotypes (cultivars, breeding lines, and plant introductions), representing three Lycopersicon species, were evaluated for resistance to Early Blight (EB) caused by the fungus Alternaria solani. Evaluations were conducted in replicated trials in multiple years under field and greenhouse conditions (with whole plants) and in growth chamber (with detached leaflets). In the field experiments, plants were evaluated for disease symptoms, and area under the disease progress curve (AUDPC) and final percent defoliation were determined. In the greenhouse experiments, plants were evaluated for percent defoliation following spray-inoculation with isolates of A. solani. In the growth chamber experiments, lesion radius, rate of lesion expansion, and final disease severity were determined for individual detached leaflets inoculated with isolates of A. solani. There were significant differences among genotypes in their response to A. solani infection in the field, greenhouse, and growth cham...
Roeland E. Voorrips - One of the best experts on this subject based on the ideXlab platform.
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VARIATION IN AGGRESSIVENESS AND AFLP AMONG Alternaria solani ISOLATES FROM INDONESIA
Indonesian Center for Agricultural Library and Technology Dissemination, 2018Co-Authors: Chaerani Chaerani, Kosim M. Kardin, Suhardi Suhardi, Eri Sofiari, Ria V. Van Ginkel, Remmelt Groenwolt, Roeland E. VoorripsAbstract:Alternaria solani is a necrotroph fungus that causes three-phased diseases in tomato. Management of the pathogen by using resistant cultivars requires knowledge on the aggressiveness and genetic diversity of the fungus. The aims of this study were to isolate A. solani from major tomato and potato producing areas in Indonesia and to study their aggressiveness and genetic variability. Twenty two A. solani isolates were recovered from Early Blighted tomato and potato in Central and West Java. A. alternata was also isolated from tomato leaves in West Java and North Sumatra, indicating that Early Blight in Indonesia may be caused by more than one Alternaria species. Resistance tests of four tomato genotypes to selected A. solani isolates revealed that local isolates were more aggressive in inciting Early Blight and stem lesion than an imported isolate from USA. This implies that introduced breeding materials must be tested to local isolates to obtain effective resistance genes. Cluster analysis based on amplified fragment length polymorphism (AFLP) obtained from EcoRI+AG and MseI+C primer amplification separated 28 local and Taiwan isolates from the US isolate, which was coincided with aggressiveness separation between the local isolates and the US isolate. Three clusters of AFLP genotypes which did not associate with geographic origin were observed among tropical isolates. The low genetic diversity among the Indonesian isolates suggests clonal population structure with wide distribution. Successful local tomato breeding requires the availability of local A. solani collection with well-characterized aggressiveness level and molecular diversity to obtain effective resistance genes.
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Assessment of Early Blight (Alternaria solani) resistance in tomato using a droplet inoculation method
Journal of General Plant Pathology, 2007Co-Authors: Reni Chaerani, Remmelt Groenwold, Piet Stam, Roeland E. VoorripsAbstract:A droplet inoculation method was used for evaluation of tomato resistance to Early Blight, a destructive foliar disease of tomato caused by Alternaria solani (Ellis and Martin) Sorauer. In this test method, leaflets are inoculated with small droplets of a spore suspension in either water or a 0.1% agar solution. Early Blight resistance was evaluated based on lesion size. The droplet method better discriminated the level of resistance (P < 0.001) for a range of spore densities in comparison with the more commonly used spray inoculation method. Lesions generated by droplet inoculation at 7 days after inoculation ranged from small flecks to almost complete Blight with an exponential-like distribution of lesion sizes. Significant correlations (r = 0.52, 0.58, and 0.63, P < 0.001) were observed across three glasshouse tests of 54 accessions including wild species using the droplet method. The most resistant accessions included wild species: one accession of Solanum arcanum, three accessions of Solanum peruvianum, one accession of Solanum neorickii, and one of Solanum chilense. Solanum pennellii and Solanum pimpinellifolium accessions were susceptible, whereas Solanum habrochaites and Solanum lycopersicum accessions ranged from susceptible to moderately resistant. The droplet test method is simple to apply, offers a fine discrimination of Early Blight resistance levels, and allows objective evaluation.
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qtl identification for Early Blight resistance alternaria solani in a solanum lycopersicum s arcanum cross
Theoretical and Applied Genetics, 2007Co-Authors: Reni Chaerani, M J M Smulders, C G Van Der Linden, B Vosman, P Stam, Roeland E. VoorripsAbstract:Alternaria solani (Ellis and Martin) Sorauer, the causal agent of Early Blight (EB) disease, infects aerial parts of tomato at both seedling and adult plant stages. Resistant cultivars would facilitate a sustainable EB management. EB resistance is a quantitatively expressed character, a fact that has hampered effective breeding. In order to identify and estimate the effect of genes conditioning resistance to EB, a quantitative trait loci (QTL) mapping study was performed in F2 and F3 populations derived from the cross between the susceptible Solanum lycopersicum (syn. Lycopersicon esculentum) cv. ‘Solentos’ and the resistant Solanum arcanum (syn. Lycopersicon peruvianum) LA2157 and genotyped with AFLP, microsatellite and SNP markers. Two evaluation criteria of resistance were used: measurements of EB lesion growth on the F2 plants in glasshouse tests and visual ratings of EB severity on foliage of the F3 lines in a field test. A total of six QTL regions were mapped on chromosomes 1, 2, 5–7, and 9 with LOD scores ranging from 3.4 to 17.5. Three EB QTL also confer resistance to stem lesions in the field, which has not been reported before. All QTL displayed significant additive gene action; in some cases a dominance effect was found. Additive × additive epistatic interactions were detected between one pair of QTL. For two QTL, the susceptible parent contributed resistance alleles to both EB and stem lesion resistance. Three of the QTL showed an effect in all tests despite methodological and environmental differences.
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Tomato Early Blight (Alternaria solani): the pathogen, genetics, and breeding for resistance
Journal of General Plant Pathology, 2006Co-Authors: Reni Chaerani, Roeland E. VoorripsAbstract:Alternaria solani causes diseases on foliage (Early Blight), basal stems of seedlings (collar rot), stems of adult plants (stem lesions), and fruits (fruit rot) of tomato. Early Blight is the most destructive of these diseases and hence receives considerable attention in breeding. For over 60 years, breeding for Early Blight resistance has been practiced, but the development of cultivars with high levels of resistance has been hampered by the lack of sources of strong resistance in the cultivated tomato and by the quantitative expression and polygenic inheritance of the resistance. In some accessions of wild species, high levels of Early Blight resistance have been found, but breeding lines still have unfavorable horticultural traits from the donor parent. Recently, the first linkage maps with loci controlling Early Blight resistance have been developed based on interspecific crosses. These maps may facilitate marker-assisted selection. This overview presents the current knowledge about the A. solani –tomato complex with respect to its biology, genetics, and breeding.
P. Simoneau - One of the best experts on this subject based on the ideXlab platform.
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Distribution of large-spored Alternaria species associated with potato and tomato Early Blight according to hosts and bioclimatic regions of Algeria
Firenze University Press, 2019Co-Authors: D. Ayad, B. Hamon, A. Kedad, Z. Bouznad, D. Aribi, P. SimoneauAbstract:Potato and tomato are important crops in Algerian agriculture, and both are threatened by abiotic and biotic stresses, and Early Blight is a major disease affecting both crops. Surveys carried out from 2012 to 2015 in 12 major growing regions for these crops yielded a total of 247 Alternaria isolates having morphological and cultural characteristics of sections Alternaria and Porri. Since Early Blight symptoms and morphological characteristics of the isolates did not allow sharp distinction between the different large-spored species of Alternaria, the isolates in section Porri, often considered primary causes of the diseases, were selected for molecular characterization by diagnostic PCR using specific primers. This allowed species identification of 147 Alternaria isolates as A. solani, A. protenta, A. grandis or A. linariae. These species were present on potato and tomato crops at varying frequencies, depending on the hosts and on bioclimatic locations. Pathogenicity tests for the four species, on detached leaflets and whole seedlings, showed that all were pathogenic to potato and tomato, with varying virulence. These results suggest that parasitic specialization of these Alternaria species on solanaceous plants should be reconsidered
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First report of Early Blight caused by Alternaria linariae on potato in Algeria
'Scientific Societies', 2018Co-Authors: D. Ayad, B. Hamon, A. Kedad, Z. Bouznad, P. SimoneauAbstract:Potato (Solanum tuberosum L.) occupies a leading place in Algerian agriculture where it is grown over an area of approximatively 160,000 ha and can be planted and harvested in virtually any month of the year. However, this production remains threatened by Early Blight disease caused by Alternaria species including A. solani, A. grandis and A. protenta (Bessadat et al., 2017; Ayad et al., 2017). High incidences of Early Blight (up to 80 %) have previously been observed in north-western parts of Algeria on potato as well as tomato (Bessadat et al., 2017). Potato disease surveys were carried out between 2012 and 2015 with sampling performed in twelve potato growing regions of Algeria. One hundred and sixty-four leaf samples exhibiting typical Early Blight symptoms (dark, elongated or circular lesions with concentric rings surrounded by a yellow halo) were collected. Small pieces (3-4 mm2) were cut off from the lesion edges, surface disinfested and plated on potato dextrose agar medium at 22°C. From the isolates obtained, eighty-two exhibited morphological characteristics associated with species of Alternaria belonging to the section Porri. Twenty-two pure cultures were induced to sporulate by plating on V8 medium and incubating for two weeks under alternating 12 h darkness and 12 h near-UV light. Although most of the isolates had typical morphological and sporulation characteristics of A. solani and A. grandis, five isolates, originating from north Algeria, produced conidia whose body and beak length (up to 108 µm and 225 µm, respectively) were in the range of those described for A. linariae (Gannibal et al., 2014). For confirmation of the identity of these isolates at the species level, partial region of the calmodulin (cal) gene was amplified using published primer set (Gannibal et al., 2014) and sequenced. Maximum-likelihood cluster analysis of the resulting nucleotide sequences (GenBank accession Nos. MH243795, MH243769, MH243793, MH243789, MH243794) and additional reference sequences of species within the section Porri confirmed that the five isolates (DA01, DA02, DA03 from the wilaya Tipaza and DA06, DA07 from the wilaya Alger) could be assigned to A. linariae with 100% sequence similarity to a reference strain (CBS 109161; GenBank accession No. JQ646254) (Woudenberg et al., 2014). To confirm pathogenicity of the five A. linariae isolates, 3-week-old leaves of susceptible varieties of tomato (Marmande and St Pierre) and potato (Spunta and Sarpomira), cultivated in pot under greenhouse at 28°C with 16h/day light, were inoculated by depositing 20 µl drops of a 104 conidia/ml suspension. Irrespective of the tested plant species and variety, all inoculated leaves showed extending lesions that may reach up 60% of the leaf area at 21 days post-inoculation. No symptom was observed on control plants treated with distilled water. Together with A. solani, A. linariae is considered as the main causal agent of tomato Early Blight (Gannibal et al., 2014) but it has never been described on potato. To our knowledge, this is the first report for the occurrence of A. linariae on potato. The fact that potato and tomato fields often co-exist in close proximity in northwestern Algeria with farmers even using tomato in rotation with potato may favor the development of A. linariae on the latter plant specie
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Alternaria species associated with Early Blight epidemics on tomato and other Solanaceae crops in northwestern Algeria
'Springer Science and Business Media LLC', 2017Co-Authors: N. Bessadat, B. Hamon, R. Berruyer, N. Bataille-simoneau, S. Benichou, M. Kihal, D.e. Henni, P. SimoneauAbstract:Early Blight is a common disease of Solanaceae crops worldwide. The occurrence of Alternaria spp. was studied during three epidemics on tomato in northwestern Algeria. Alternaria was detected in more than 80 % of the diseased plant samples and accounted for more than 50 % of the total fungal isolates recovered from these samples. Morphological and molecular investigations revealed that small-spored isolates producing beaked conidia, i.e. belonging to the section alternaria, were prominent in most of the surveyed locations representing more than 80 % of the total Alternaria isolates in three locations (Mascara, Ain Témouchent and Sidi Belabbèsse). Based on their sporulation patterns they were recognized as A. alternata and A. tenuissima. Small-spored isolates producing conidia without beak and assigned to A. consortialis were also found at a low frequency (< 1 %). Large-spored isolates producing conidia ended by typical long beaks and identified as A. linariae (syn. A. tomatophila), A. solani and A. grandis were also recovered from all the sampled areas and represented 33.8 %, 6.3 % and 1.3 % of the total Alternaria isolates, respectively. Pathogenicity tests on tomato with a selection of 85 strains representative of the isolates collection revealed that all the tested isolates were able to produce extending lesions on inoculated leaves albeit with variable intensity. Large-spored species included the most aggressive isolates. Small-spored Alternaria, although less aggressive than large-spored Alternaria, had the ability to provoke brown necrotic spots and circumstantially developed synergistic interactions in mixed infections with moderately aggressive isolates of A. linariae
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First report of tomato Early Blight caused by Alternaria grandis in Algeria
Plant Disease, 2016Co-Authors: N. Bessadat, B. Hamon, D.e. Henni, P. SimoneauAbstract:Tomatoes (Solanum lycopersicum) are widely cultivated in Algeria throughout the year. In northwestern growing areas, characterized by temperate humid climates, severe Early Blight symptoms (i.e., black lesions surrounded by a yellow halo) on tomato leaves are regularly observed. In 2013, diseased samples were collected from various cultivars in five farms of the Mostaganem region where average disease incidence reached 50%. Plant material was cut into ∼2-mm pieces, surface sterilized in 0.1% (v/v) Na hypochlorite for 2 min, transferred into potato agar medium, and incubated for 48 h at 25°C. Fungal mycelium developing from the lesion margins was transferred to potato carrot agar medium and further incubated for 7 days alternating darkness and cool-white fluorescent light to induce sporulation. Both small- and large-spored Alternaria isolates were obtained. While most of the large-spored isolates had morphological characteristics of A. linariae (syn. A. tomatophila) (Woudenberg et al. 2014), large-spored isolates from one location (Mamache) produced ovoid conidia whose length and width were 149.8 ± 8.9 µm and 16.4 ± 1.3 µm, respectively, ended by a single beak measuring up to 120 µm. Based on these morphological characteristics and host origin, these isolates were initially described as A. solani (Simmons 2000). To confirm the identification at the species level, DNA was extracted from mycelium of four representative isolates. As polymorphism in the ITS regions of rDNA is too low to delineate species within the Alternaria section Porri (Woudenberg et al. 2014), partial regions of the glyceraldehyde-3-phosphate dehydrogenase (gpd) and of the calmodulin (cal) genes were amplified using published primer sets (Gannibal et al. 2014; Woudenberg et al. 2014). For two isolates (NB250 and NB252), the sequences of the amplified products (GenBank Accession Nos. KR911747, KR911752 KR911765, and KR911767) were 100% identical to corresponding sequences of A. solani isolate CBS 109157 (GQ180080 and KJ397981). The gpd and cal sequences of the remaining isolates (NB248 and NB249, GenBank Accession Nos. KR911748, KR911754, KR911763, and KR911764) shared 100% sequence homology to A. grandis isolate CBS109158 (JQ646341 and JQ646249) and they were therefore assigned to this species. To confirm pathogenicity on tomato, the four isolates were spray inoculated (104 conidia/ml) on leaves of 3-week-old tomato plants (cv. Saint Pierre) in the greenhouse. Three replicates were performed for each test. Plants were rated for disease symptoms up to 21 days post inoculation (dpi). No symptom was observed on control plants treated with distilled water. All plants inoculated with A. solani and A. grandis isolates produced extending lesions on leaves albeit with variable virulence (affected leaf area from 50 to 80% at 21 dpi for NB249 and NB250, respectively). To our knowledge, this is the first report of A. grandis infecting tomato in Algeria and in Africa. Moreover, A. grandis has been reported on potato crops in North and South America (Simmons 2000; Rodrigues et al. 2010), but never on tomato. The fact that potato and tomato fields often coexist in close proximity in northwestern Algeria even with farmers using potato in rotation with tomato may favor the development of A. grandis on the latter plant species.
N Rosenzweig - One of the best experts on this subject based on the ideXlab platform.
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first report of boscalid and penthiopyrad resistant isolates of alternaria solani causing Early Blight of potato in michigan
Plant Disease, 2013Co-Authors: Timothy D Miles, N Rosenzweig, K L Fairchild, A Merlington, W W Kirk, P S WhartonAbstract:Early Blight of potato (Solanum tuberosum) is caused by Alternaria solani and occurs annually in Michigan. If left uncontrolled, it can result in yield losses exceeding 20% and impact stored potatoes. The disease is commonly managed using succinate dehydrogenase inhibitor (SDHI) fungicides (1). Unfortunately, recent studies have shown that SDHI resistance has increased dramatically over the past 2 years in A. solani populations (1,2). To investigate the occurrence of SDHI resistance in Michigan, potato leaves with Early Blight symptoms were collected from fields in Montcalm and Ionia counties, MI, in 2012. To obtain A. solani isolates from leaves, small pieces of leaf tissue (5 × 5 mm) were excised from the center of lesions and transferred on to water agar. Plates were incubated at 25°C overnight to allow conidia to germinate. Single germinated A. solani conidia were transferred to potato dextrose agar (PDA) and incubated at 25°C for 7 days. The identity of cultures was confirmed by colony and conidial m...
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evaluation of qoi fungicide application strategies for managing fungicide resistance and potato Early Blight epidemics in wisconsin
Plant Disease, 2008Co-Authors: N Rosenzweig, Zahi K Atallah, Gilberto Olaya, W R StevensonAbstract:ABSTRACT Potato Early Blight (Alternaria solani) is a yield-limiting disease and control depends primarily on multiple fungicide applications. Azoxystrobin, registered in the United States in 1999, initially provided outstanding Early Blight control. Within 3 years, approximately 80% of the total potato acreage was being treated with azoxystrobin and other quinone outside inhibitor (QoI), fungicides registered subsequently. Alternaria solani isolates with decreased in vitro sensitivity to azoxystrobin were detected in Wisconsin during 2001. Field experiments were conducted in 2001 to 2003 to evaluate season-long fungicide programs and test fungicide resistance management strategies. The fungicide program recommended to growers at that time, which consisted of three applications of azoxystrobin for weeks 1, 3, and 5 alternated with applications of chlorothalonil at label recommended rates, was effective in controlling Early Blight when conditions were conducive to disease development. Mean sensitivity in v...
