Identification of QoI fungicide-resistant genotypes of the wheat pathogen Zymoseptoria tritici in Algeria

Septoria tritici blotch caused by Zymoseptoria tritici is currently one of the most damaging diseases on bread and durum wheat crops worldwide. A total of 120 monoconidial isolates of this fungus were sampled in 2012 from five distinct geographical locations of Algeria (Guelma, Annaba, Constantine, Skikda and Oran) and assessed for resistance to Quinone outside Inhibitors (QoI), a widely used class of fungicides for the control of fungal diseases of wheat. Resistance was screened using a mismatch PCR assay that identified the G143A mitochondrial cytochrome b substitution associated with QoI resistance. The isolates were QoI-sensitive, since all possessed the G143 wild-type allele, except for three isolates (two from Guelma and one from Annaba), which had fungicide resistance and possessed the A143 resistant allele. QoI resistance was confirmed phenotypically using a microplate bioassay in which the resistant isolates displayed high levels of half-maximal inhibitory azoxystrobin concentrations (IC50s) when compared to sensitive reference isolates. Genetic fingerprinting of all isolates with microsatellite markers revealed that the three resistant isolates were distinct haplotypes, and were are not genetically distinguishable from the sensitive isolates. This study highlights QoI-resistant genotypes of Z. tritici in Algeria for the first time, and proposes a management strategy for QoI fungicide application to prevent further spread of resistance across the country or to other areas of Northern Africa

A survey of the combined effects of waterlogging and salinity on fruit yield in the date palm groves of the Wargla basin, Algeria

Introduction. While researchers have paid considerable attention to the effect of soil salinity on crop yield, methodological impediments remain when salinity is combined with other growth factors, especially in farmers' fields. A specific methodology was adapted to assess the effect of waterlogging and salinity on date palm yield ( Phoenix dactylifera L. cv. Deglet Noor). Materials and methods. Date palm yield, water table depth, irrigation water, groundwater and soil salinity were measured in 167 field plots located in five irrigation sectors of the Wargla basin (Algeria). Variance analysis and a boundary line approach were combined to analyze actual and potential yields according to environmental stresses. Results and discussion. High soil salinity resulted from saline irrigation water and a shallow water table. Actual yield decreased with the increase in soil salinity, the decrease in water table depth, and the presence of a gypsum-cemented horizon within the soil profile. The significant effect of the interaction between water table depth and soil salinity showed that the crop responded to the most severe stress rather than to combinations of the individual effects. Potential yield was assessed according to classes of water table depth, soil salinity and the occurrence of a gypsum-cemented horizon. The relationship between soil salinity and potential yield was calibrated according to two models. The limiting factors in order of decreasing importance were shallow water table, high soil salinity and occurrence of a gypsum-cemented horizon for 38.3%, 16.8% and 2.4% of the field plots, respectively; there was no limiting factor for 42.5% of the field plots. In certain sectors, actual yields remained far below potential yields and the additional effect of irrigation water salinity could thus be considered. (Résumé d'auteur

Etude de quelques expressions morpho- physiologiques chez trois génotypes de blé dur pour la sélection à la tolérance au déficit hydrique

La présente contribution est une exploration des aptitudes germinatives de semences de trois génotypes de blé dur, permettant d’apprécier le niveau de vigueur de celles-ci. Le pourcentage de germination, la cinétique de croissance à un stade juvénile, le test d’absorption d’eau en sont quelques paramètres effectués. Un autre paramètre physique, à savoir la taille des semences, a aussi été pris en considération ; pour apprécier l’effet intra et inter variétés. Les résultats auxquels nous avons abouti montrent que le pourcentage de germination, expriméaprès 5 jours et 10jours ne semble pas discriminant à ce point et les résultats, malgré de légères variations restent quelque peu similaires. La cinétique de croissance, quant à elle, présente des différences entre les génotypes étudiés. Le test d’absorption d’eau a montré que les génotypes présentent une bonne vigueur. Au champ, il est à remarquer le caractère distinctif de présence de cire (composé donnant une texture lisse des feuilles) chez lavariété Ammar6, ce qui lui confère en principe des qualités adaptatives de tolérance au stress hydrique. Cette étude nous aura permis une exploration préliminaire simple, rapide mais fiable tout autant, des semences, avant leur utilisation dans des essais en plein champ.Mots clés : blé dur-stress hydrique- physiologie- adaptation-vigueur. Study of some morpho- physiological expressions in three durum wheatgenotypes for drought tolerance selectionThe present contribution is an exploration of germinative abilities of seeds from three durum wheat genotypes, allowing us to appreciate level of this vigor. Germination percentage, kinetic growth at seedling stage, water absorption were performed. Another physical parameter, seed size, was also chosen in order to appreciate its effect between and within varieties. Results that have been obtained show that germination percentages, expressed after 5 days and 10 days, does not seem to be discriminating at that point even though some light differences. Kinetic growth shows differences among genotypes. Water absorption showed varieties had higher vigor. Simeto that had the highest thousand kernel weight, seems to be correlated to water absorption test. In the field, waxiness was found in cv Ammar6. This study would have allowed us to perform simple, rapid and reliable tests for early screening before field planting.Keys words: durum wheat-water stress- physiology- adaptation-vigor

Effects of accelerated ageing on germination and establishment of vigorous young seedlings from macrobiotic seeds: case of durum wheat

treatment of accelerated ageing of Algerian durum wheat was used in order to predict the ability to storage of six varieties widely cultivated in Algeria, Bousellam, Setefis, Megress, Ofanto, Chen’s et Saoura The results that have been obtained show that seed that have undergone ageing treatment for two days have high abilities of germination as compared to that have undergone treatment for four days, decrease of rate of  germination was more important except for two varieties, Bousellam et Setefis Difference was as fact very highly significant. A decrease highly significant of the mean number of roots was noticed for durum varieties as compared to the check, Bousselem after four days of treatment, showed the best result. Concerning the mean of shoot length, and mean root length, a decrease not significant of growth as compared to the check was observed ; the ability to grow this better for Bousselem. This last one seem show ever to be some how different to the other varieties, in this sense that germination power is more easy and translate an ability higher to conservation and to storage. Growths higher of shoots and roots and mean roots number demonstrate that.Key words: seed- physiology- storage- accelerated ageing- Algeri

Effet du stockage sur la vigueur et la viabilité des semences de deux variétés de blé dur (Triticum durum, Desf)

Les effets du stockage ont été étudiés sur des semences de blé dur (Triticum  durum). L’objectif repose sur l’évaluation de différentes altérations observées au cours du stockage. Celles-ci portent sur l’indice de viabilité et de vigueur des  semences de deux variétés, conservées durant 6 mois, 1 an et 2 ans dans des conditions ambiantes ; température avec des minima de 10°C et des maxima de  39°C et une humidité relative qui oscille entre 48 à 83%. Les détériorations  provoquées par la durée du stockage se manifestent, par une diminution de la vitesse et du taux de germination, un ralentissement de la croissance des plantules et l’apparition de plantules anormales. Par contre nous observons une augmentation de fuite d’électrolytes, du taux des protéines totales et de proline pour les semences âgées de 2 ans.Mots clés: blé dur – stockage–viabilité-germination- proline.Effect of storage on the vigor and viability of two varieties of durum wheat(Triticum durum, Desf)The effects of storage were studied in wheat seeds (Triticum durum). The objective is based on the evaluation of different alterations observed during storage. These relate to the viability index and seed vigor of two varieties stored for 6 months, 1 year and 2 years at ambient conditions; with temperatures of 10 ° C and maximum 39 ° C and a relative humidity that ranges between 48-83%. The damage caused by the storage time manifested by a reduction in the speed and rate of germination; slower seedling growth and the appearance of abnormal seedlings. Otherwise we observe an increase in electrolyte leakage, the rate of total protein and proline for 2 years older seeds.Keywords: durum wheat - storage –viability-germination -proline

Etude de lignées de blé tendre utilisées dans un programme d’amélioration génétique pour la résistance à la rouille jaune en Algérie

Trois cultivars, Hiddab 1220, Yr18/3* Avocet 'S' et Ciano 79, ont été étudiés. HD est considérée comme une base génétique d’adaptation aux conditions locales. Les variétés Yr18/3* Avocet 'S' et Ciano 79, sont des lignées avec des gènes majeurs de résistance Yr18 et Yr27, choisies dans du matériel du CIMMYT. Sur la base de cette étude, Ciano 79 portant le gène Yr27, a montré une meilleure résistance à la rouille jaune dans les conditions locales et une meilleure qualité technologique, vu la présence de sous-unités de gluténines à HMW 5+10 du locus Glu-D1. De ce fait il peut être utilisé dans la production de nouvelles variétés de blé tendre résistantes et de bonne qualité technologique. Le gène Yr18 a montré un niveau de résistance modéré ; ce gène pouvant être utilisé avec d’autre gène par pyramidage, qui consiste à l’incorporation des gènes de résistance spécifiques majeurs pour produire des variétés présentant une résistance plus durable aux rouilles. Les résultats de cette étude, seront approfondis par la caractérisation par marqueurs moléculaires et analyse de la composition des sous-unités de gluténines à haut poids moléculaire (HMW), des descendances obtenues, afin d’identifier des pré-lignées qui seront utilisées dans un programme d’amélioration de résistance à la rouille jaune.Mots clé : Blé tendre-gènes de résistance rouille jaune-sévérité de la maladie- gluténine à HWM

Mating type distribution provides evidence for sexual reproduction of Mycosphaerella graminicola in Algeria

International audienceSeptoria tritici blotch caused by Mycosphaerella graminicola is currently the most frequently occurring and economically damaging disease on wheat crops worldwide. A total of 120 single-conidial isolates of this fungus (60 from bread wheat and 60 from durum wheat) were sampled in 2012 from five distinct geographical locations of Algeria and analyzed for mating type distribution to provide insight into the potential of sexual reproduction. The mating type of each isolate was identified using a multiplex PCR that amplifies either a MAT1-1 or a MAT1-2 fragment from mating type loci. Both idiomorphs were scored at equal frequencies according to the χ2 test at different scales. They were found to occur at equal proportions at the whole country level (46 % MAT1-1 vs. 54 % MAT1-2) and at the level of each sampled location. The two mating types were also found at equal frequencies on both host species at the country scale (47 % MAT1-1 vs. 53 % MAT1-2 on bread wheat and 45 % MAT1-1 vs. 55 % MAT1-2 on durum wheat) and irrespective of the sampled locations. This equal mating type distribution at both geographic and host species levels suggests a large potential for sexual reproduction of M. graminicola in Algeria and indicates a lack of specificity between mating types and host species in the case of the wheat-M. graminicola pathosystem

Effects of hydro-edaphic environment on the rooting of date palm (Phoenix dactylifera L.) Deglet Noor in the Ouargla Basin (south-east algeria)

During the last decade, the Ouargla basin went through a problem of groundwater rise that had prejudicial consequences on the oasis environment. We studied the impact of hydroedaphic environment on root systems of the Deglet Noor date palm in the date-producing areas of Ouargla basin. The results indicated that 53.9% of date-producing farms showed a water table depth between 29 and 119.4 cm. Root distribution of date palms 80 cm far from the trunk showed that 56.9% of the palm plantations exhibit a rooting depth between 27 and 119 cm, including 3% of which is caused by the gypseous and gypseous-calcareous crusts alone, 10.8% of which is caused by the water table combined with the gypseous and gypseous-calcareous crusts and finally 43.1% of which caused by the water table. Electric conductivity of groundwater varied from 10 to 39.7 dS. m-1. The correlation analysis confirmed that lower water table depths and, gypseous and gypseous-calcareous crusts caused a decrease in the root system depth. Roots avoided both water saturation zone and mechanical resistance in the crusts, causing them to develop in the side direction. Salinity of groundwater proved to be less important to rooting of the date palm compared to level of the ground water.La cuvette d’Ouargla a connu durant cette dernière décennie un problème de remontée de la nappe phréatique. Cela a eu des conséquences préjudiciables sur l’environnement oasien. Nous avons étudié l’impact de l’environnement hydro-édaphique sur l’enracinement du palmier dattier Déglet Nour dans les périmètres phoenicicoles de la cuvette d’Ouargla. Les résultats obtenus montrent que 53,9% des exploitations phoenicicoles présentent une nappe phréatique ayant une profondeur comprise entre 29 et 119,4 cm. L’étude de l’enracinement du palmier dattier, à 80 cm du tronc, a montré que 56,9% des palmeraies présentent un enracinement compris entre 27 et 119 cm de profondeur, dont 3% à cause des croûtes gypseuses et gypso-calcaires, 10,8% à cause de la nappe et des croûtes gypseuses et gypso-calcaires et enfin 43,1% à cause de la nappe phréatique. La conductivité électrique des eaux phréatiques varie de 10 à 39,7 dS. m-1. L’étude des corrélations montre que la faible profondeur de la nappe phréatique ainsi que des croûtes gypseuses et calcaires diminuent la profondeur d’enracinement. Les racines fuient la zone de saturation en eau et la résistance mécanique des croûtes pour se développer dans le sens latéral. La salinité des eaux phréatiques présente moins d’effet sur l’enracinement du palmier dattier comparée au niveau de la nappe phréatique.Daddi-Bouhoun Mustapha, Brinis Louhichi, Saker Mohamed-Lakhdar, Côte Marc, Rabier Jacques. Effects of hydro-edaphic environment on the rooting of date palm (Phoenix dactylifera L.) Deglet Noor in the Ouargla Basin (south-east algeria). In: Ecologia mediterranea, tome 35,2009. pp. 41-48