Annual surveys of barley and wheat diseases were conducted in Eritrea from 2000 to 2002. The surv... more Annual surveys of barley and wheat diseases were conducted in Eritrea from 2000 to 2002. The surveys covered six zones of the central highlands where barley and wheat are grown. The main diseases of barley were netform net blotch, spot-form net blotch, leaf rust and scald. Other, less important diseases were loose smut, covered smut, barley stripe and septoria leaf blotch. Wheat was mainly affected by yellow rust and leaf rust. Loose smut, septoria leaf spot and tan spot diseases were less prevalent. The average incidence of these diseases varied according to the zone. Among barley diseases, net blotch incidence was high in four of the six zones surveyed. Leaf rust occurred at medium incidence in five zones. Loose smut was more severe in the southern highland plains, while covered smut was more common in the south-eastern highland terraces. For wheat, yellow rust incidence was high in two zones. Areas with a high incidence of yellow rust were not necessarily those with a high incide...
Tan spot (TS), caused by Pyrenophora tritici-repentis (Ptr), has gained significant importance in... more Tan spot (TS), caused by Pyrenophora tritici-repentis (Ptr), has gained significant importance in Tunisia. In this study, a Mediterranean durum wheat collection of 113 accessions were evaluated under field conditions, during the 2018–2019 cropping season, for resistance to Ptr at Koudia experimental station in Bou Salem (Tunisia). The disease progress curve (AUDPC) was used to screen this collection, and the effect of days to heading (DH) and plant height (PH) were evaluated in relation to TS resistance. No significant correlation of PH with AUDPC was found, yet a significant correlation (r = 0.212, p ≤ 0.05) was established between DH and AUDPC scores, suggesting that DH may have an effect on TS development. Moreover, correlation between seedling and adult reactions was significant (r = 0.695, p ≤ 0.001). Although susceptible accessions clustered separately from resistant accessions, the clustering was independent of the country of origin and the status of improvement of the wheat ...
Rhynchosporium commune was recently introduced into the Middle East, presumably with the cultivat... more Rhynchosporium commune was recently introduced into the Middle East, presumably with the cultivated host barley (Hordeum vulgare). Middle Eastern populations of R. commune on cultivated barley and wild barley (H. spontaneum) were genetically undifferentiated and shared a high proportion of multilocus haplotypes. This suggests that there has been little selection for host specialization on H. spontaneum, a host population often
Phenotypic data collected in on-station field trials and genotypic data for breeding materials fr... more Phenotypic data collected in on-station field trials and genotypic data for breeding materials from the CIMMYT Durum Wheat breeding program are included in this study.
Tan spot, caused by Pyrenophora tritici-repentis (Ptr), is a widespread foliar disease of wheat, ... more Tan spot, caused by Pyrenophora tritici-repentis (Ptr), is a widespread foliar disease of wheat, which is becoming important in North Africa particularly in Tunisia. To assess the pathogenic variation of Ptr in Tunisia, characterized 84 single conidium isolates of Ptr were characterized from durum wheat cultivars, sampled during the 2017-2018 cropping season. The virulence of isolates were assessed, under controlled conditions, on a standard differential set of six wheat genotypes. Ptr races 2, 4, 5, 6, 7 and 8 were identified, the first such information available for Tunisia. Race 2, commonly found in North America, South America and Asia, was identified for the first time in North Africa, at a low frequency of 5%. Races 5 and 7 were the most frequent, representing, respectively, 39% and 43% of the isolates tested. Only 8% of the isolates were classified as race 8, while 4% were identified race 6. Race 6 was only detected at the experimental station in the North Western region of T...
1 Universite M’hamed Bougra, Boumerdes, Faculte des Sciences, Departement de Biologie, Laboratoir... more 1 Universite M’hamed Bougra, Boumerdes, Faculte des Sciences, Departement de Biologie, Laboratoire de Biologie Moleculaire, 16 Avenue Rue de l’independance, Boumerdes, Algerie. 2 International Center for Agricultural Research in Dry Areas, P.O. Box 5466, Aleppo Syria. 3 International Maize and Wheat Improvement Center, Apdo. Postal 6-641,06600, Mexico DF, Mexico. 4 Ecole Nationale Superieure d’Agronomie, Departement de Botanique, El-Harrach, Alger, Algerie.
Microsatellite markers were used to assess genetic diversity of Mycosphaerella graminicola at a m... more Microsatellite markers were used to assess genetic diversity of Mycosphaerella graminicola at a micro geographical scale in Tunisia. Forty five (45) isolates were sampled and assessed using seven pairs of single-locus microsatellite primers not previously tested on populations of M. graminicola in Tunisia. Genetic diversity of the field population ranged from 0.403 to 0.555 with an average of 0.484. A high level of genetic diversity was found at a sharp scale throughout the pathogen population tested. Among 45 isolates sampled, 39 different multi locus genotypes (MLG) were identified. Cluster analysis (UPGMA) showed that 86% of the isolates tested were distinct. The high degree of DNA polymorphism, the large number of different molecular genotypes and the pattern of cluster analysis suggest that sexual ascospores and/or asexual spores of a highly mutable local population could have contributed to the genetic diversity of M. graminicola in Tunisia. Keywords : Durum wheat, genetic div...
Durum wheat (Triticum turgidumL. subsp.durum) landraces represent a prominent genetic resource fo... more Durum wheat (Triticum turgidumL. subsp.durum) landraces represent a prominent genetic resource for Mediterranean farming systems and breeding programs. Fourteen landraces sampled in Tunisia were genotyped with 9 microsatellite markers and characterized with 15 morphological descriptors, including resistance to the fungal diseaseSeptoria triticiblotch (STB). The genetic diversity, nearly was as important within landraces populations (45%) than between populations (54%). It was structured in seven genetic groups and was only partly explained by the variety name or the locality of origin. Populations were also greatly diversified phenotypically (Shannon-Weaver H’=0.54) with traits related to spike and awn colours being the most diversified. Resistance to STB was either qualitative in two populations or with varying degrees of quantitative resistance in the others. A Pst-Fstcomparison indicate a local adaptation of the populations. Overall, the genetic structure of Tunisian durum wheat ...
Mixtures of cultivars with contrasting levels of disease resistance are capable of suppressing in... more Mixtures of cultivars with contrasting levels of disease resistance are capable of suppressing infectious diseases in wheat, as demonstrated in numerous field experiments. Most studies focused on airborne pathogens in bread wheat, while splash-dispersed pathogens have received less attention, and no studies have been conducted in durum wheat. We conducted a field experiment in Tunisia, a major durum wheat producer in the Mediterranean region, to evaluate the performance of cultivar mixtures in controlling the polycyclic, splash-dispersed disease Septoria tritici blotch (STB) in durum wheat. To measure STB severity, we used a novel, high-throughput method based on digital analysis of images captured from 1284 infected leaves collected from 42 experimental plots. This method allowed us to quantify pathogen reproduction on wheat leaves and to acquire a large dataset that exceeds previous studies with respect to accuracy and statistical power. Our analyses show that introducing only 25%...
Annual surveys of barley and wheat diseases were conducted in Eritrea from 2000 to 2002. The surv... more Annual surveys of barley and wheat diseases were conducted in Eritrea from 2000 to 2002. The surveys covered six zones of the central highlands where barley and wheat are grown. The main diseases of barley were netform net blotch, spot-form net blotch, leaf rust and scald. Other, less important diseases were loose smut, covered smut, barley stripe and septoria leaf blotch. Wheat was mainly affected by yellow rust and leaf rust. Loose smut, septoria leaf spot and tan spot diseases were less prevalent. The average incidence of these diseases varied according to the zone. Among barley diseases, net blotch incidence was high in four of the six zones surveyed. Leaf rust occurred at medium incidence in five zones. Loose smut was more severe in the southern highland plains, while covered smut was more common in the south-eastern highland terraces. For wheat, yellow rust incidence was high in two zones. Areas with a high incidence of yellow rust were not necessarily those with a high incide...
Tan spot (TS), caused by Pyrenophora tritici-repentis (Ptr), has gained significant importance in... more Tan spot (TS), caused by Pyrenophora tritici-repentis (Ptr), has gained significant importance in Tunisia. In this study, a Mediterranean durum wheat collection of 113 accessions were evaluated under field conditions, during the 2018–2019 cropping season, for resistance to Ptr at Koudia experimental station in Bou Salem (Tunisia). The disease progress curve (AUDPC) was used to screen this collection, and the effect of days to heading (DH) and plant height (PH) were evaluated in relation to TS resistance. No significant correlation of PH with AUDPC was found, yet a significant correlation (r = 0.212, p ≤ 0.05) was established between DH and AUDPC scores, suggesting that DH may have an effect on TS development. Moreover, correlation between seedling and adult reactions was significant (r = 0.695, p ≤ 0.001). Although susceptible accessions clustered separately from resistant accessions, the clustering was independent of the country of origin and the status of improvement of the wheat ...
Rhynchosporium commune was recently introduced into the Middle East, presumably with the cultivat... more Rhynchosporium commune was recently introduced into the Middle East, presumably with the cultivated host barley (Hordeum vulgare). Middle Eastern populations of R. commune on cultivated barley and wild barley (H. spontaneum) were genetically undifferentiated and shared a high proportion of multilocus haplotypes. This suggests that there has been little selection for host specialization on H. spontaneum, a host population often
Phenotypic data collected in on-station field trials and genotypic data for breeding materials fr... more Phenotypic data collected in on-station field trials and genotypic data for breeding materials from the CIMMYT Durum Wheat breeding program are included in this study.
Tan spot, caused by Pyrenophora tritici-repentis (Ptr), is a widespread foliar disease of wheat, ... more Tan spot, caused by Pyrenophora tritici-repentis (Ptr), is a widespread foliar disease of wheat, which is becoming important in North Africa particularly in Tunisia. To assess the pathogenic variation of Ptr in Tunisia, characterized 84 single conidium isolates of Ptr were characterized from durum wheat cultivars, sampled during the 2017-2018 cropping season. The virulence of isolates were assessed, under controlled conditions, on a standard differential set of six wheat genotypes. Ptr races 2, 4, 5, 6, 7 and 8 were identified, the first such information available for Tunisia. Race 2, commonly found in North America, South America and Asia, was identified for the first time in North Africa, at a low frequency of 5%. Races 5 and 7 were the most frequent, representing, respectively, 39% and 43% of the isolates tested. Only 8% of the isolates were classified as race 8, while 4% were identified race 6. Race 6 was only detected at the experimental station in the North Western region of T...
1 Universite M’hamed Bougra, Boumerdes, Faculte des Sciences, Departement de Biologie, Laboratoir... more 1 Universite M’hamed Bougra, Boumerdes, Faculte des Sciences, Departement de Biologie, Laboratoire de Biologie Moleculaire, 16 Avenue Rue de l’independance, Boumerdes, Algerie. 2 International Center for Agricultural Research in Dry Areas, P.O. Box 5466, Aleppo Syria. 3 International Maize and Wheat Improvement Center, Apdo. Postal 6-641,06600, Mexico DF, Mexico. 4 Ecole Nationale Superieure d’Agronomie, Departement de Botanique, El-Harrach, Alger, Algerie.
Microsatellite markers were used to assess genetic diversity of Mycosphaerella graminicola at a m... more Microsatellite markers were used to assess genetic diversity of Mycosphaerella graminicola at a micro geographical scale in Tunisia. Forty five (45) isolates were sampled and assessed using seven pairs of single-locus microsatellite primers not previously tested on populations of M. graminicola in Tunisia. Genetic diversity of the field population ranged from 0.403 to 0.555 with an average of 0.484. A high level of genetic diversity was found at a sharp scale throughout the pathogen population tested. Among 45 isolates sampled, 39 different multi locus genotypes (MLG) were identified. Cluster analysis (UPGMA) showed that 86% of the isolates tested were distinct. The high degree of DNA polymorphism, the large number of different molecular genotypes and the pattern of cluster analysis suggest that sexual ascospores and/or asexual spores of a highly mutable local population could have contributed to the genetic diversity of M. graminicola in Tunisia. Keywords : Durum wheat, genetic div...
Durum wheat (Triticum turgidumL. subsp.durum) landraces represent a prominent genetic resource fo... more Durum wheat (Triticum turgidumL. subsp.durum) landraces represent a prominent genetic resource for Mediterranean farming systems and breeding programs. Fourteen landraces sampled in Tunisia were genotyped with 9 microsatellite markers and characterized with 15 morphological descriptors, including resistance to the fungal diseaseSeptoria triticiblotch (STB). The genetic diversity, nearly was as important within landraces populations (45%) than between populations (54%). It was structured in seven genetic groups and was only partly explained by the variety name or the locality of origin. Populations were also greatly diversified phenotypically (Shannon-Weaver H’=0.54) with traits related to spike and awn colours being the most diversified. Resistance to STB was either qualitative in two populations or with varying degrees of quantitative resistance in the others. A Pst-Fstcomparison indicate a local adaptation of the populations. Overall, the genetic structure of Tunisian durum wheat ...
Mixtures of cultivars with contrasting levels of disease resistance are capable of suppressing in... more Mixtures of cultivars with contrasting levels of disease resistance are capable of suppressing infectious diseases in wheat, as demonstrated in numerous field experiments. Most studies focused on airborne pathogens in bread wheat, while splash-dispersed pathogens have received less attention, and no studies have been conducted in durum wheat. We conducted a field experiment in Tunisia, a major durum wheat producer in the Mediterranean region, to evaluate the performance of cultivar mixtures in controlling the polycyclic, splash-dispersed disease Septoria tritici blotch (STB) in durum wheat. To measure STB severity, we used a novel, high-throughput method based on digital analysis of images captured from 1284 infected leaves collected from 42 experimental plots. This method allowed us to quantify pathogen reproduction on wheat leaves and to acquire a large dataset that exceeds previous studies with respect to accuracy and statistical power. Our analyses show that introducing only 25%...
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