Short Communication
Reaction of Five Durum Wheat Tunisian Varieties Toward Some Populations of Pyrenophora tritici-repentis Collected From Different Geographical Origins Salma Tissaoui, LR14AGR02 LR/Bioagresseurs et Protection Intégrée en Agriculture, INAT, Université de Carthage, Tunis, Tunisia, Sana Kamel, Département d’Agronomie et Biotechnologies Végétales, INAT, Université de Carthage, Tunis, Tunisia, Amira Mougou-Hamdane, LR14AGR02 LR/Bioagresseurs et Protection Intégrée en Agriculture, INAT, Université de Carthage, Tunis, Tunisia, Mejda Chérif, Département d’Agronomie et Biotechnologies Végétales, INAT, Université de Carthage, Tunis, Tunisia, and Bouzid Nasraoui, LR14AGR02 LR/Bioagresseurs et Protection Intégrée en Agriculture, INAT, Université de Carthage, Tunis, Tunisia __________________________________________________________________________ ABSTRACT Tissaoui, S., Kamel, S., Mougou-Hamdane, A., Chérif, M., and Nasraoui, B. 2016. Reaction of five durum wheat Tunisian varieties toward some populations of Pyrenophora tritici-repentis collected from different geographical origins. Tunisian Journal of Plant Protection 11: 239-243. This preliminary study aimed to evaluate reaction of fiveTunisian commercial varieties of durum wheat against six populations of Pyrenophora tritici-repentis (Ptr), the causal agent of tan spot, collected from different Tunisian northern regions. Seedlings were sown in growth chamber and inoculated by foliar spray of Ptr suspension. The reactions of durum wheat varieties were evaluated 10 days postinoculation based on necrosis and/or chlorosis severity on leaves. This assessment revealed symptoms of variable intensity on wheat seedlings, with populationsP1 and P6 three times more aggressive than population P5. The variety behavior was quite similar, however Salim followed by Maali were found be the most susceptible ones and Nasr was the most relatively resistant. Keywords: Durum wheat, population, Pyrenophora tritici-repentis, reaction, variety
_________________________________________________________________________ Tan spot disease of durum wheat (Triticum durum) is a fungal disease caused by Pyrenophora tritici-repentis (Ptr). It causes also the same disease in common wheat (Triticum aestivum) and
other grasses hosts (5, 6). This disease can spread seriously under favorable climatic conditions where wheat crops were grown as monoculture associated to minimum soil cultivation (1). This disease can lead to decreased production (5, 6, 7, 11) and its impact on durum wheat is variable depending on cropping seasons. Unlike some Maghreb countries (3, 4) and many other countries in the world (3, 4, 5, 6, 9), tan spot could be considered as an emerging wheat disease
Corresponding author: Bouzid Nasraoui Email:
[email protected] Accepted for publication 17 November 2016 Tunisian Journal of Plant Protection
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in Tunisia and no interest had been given to this disease. This preliminary assay aims to evaluate the reactions of Tunisian durum wheat varieties currently commercialized (6, 7) against six Tunisian populations of Ptr. Seeds of five varieties of durum wheat (Karim, Razzek, Nasr, Maali, and
Salim) were used in this assay. Populations of Ptr have been isolated from symptomatic plants collected from different northern regions of Tunisia (Wad Mliz, Boussalem, Beja, Gboullat, Missaadine, and Borj ElAamri) as indicated on the map (Fig. 1).
Fig. 1. Tunisian geographical origin of durum wheat samples showing tan spot symptoms.
Leaves exhibiting visible lesions of tan spot were cut and sterilized in hypochlorite solution during 3 min and in alcohol 70° for 10 s. They were rinsed in sterile distilled water three times. These fragments were dried and placed in Petri dishes on a V8-Potato Dextrose Agar (20%:80%) culture medium (2, 8).They were incubated at 20°C for 10 days (6) by alternating light and darkness with a 12 h photoperiod (6). The essay was conducted in growth chamber (10) according to a completely randomized design with five replicates per individual treatment. The sowing was performed in pots with five Tunisian Journal of Plant Protection
seeds per pot. Seedlings were inoculated at the 2- to 3-true-leaf stage. Inoculum was obtained by scratching the mycelium with spores and suspending all in 200 ml of sterile distilled water. Then, wheat seedlings were sprayed with inoculum and were covered by transparent plastic film for 24 h to keep high humidity required for infection. The tan spot disease was evaluated after 10 days postinoculation based on 0 to 5 rating scale (0 =Absence of lesions on leaves;1 = Small dark brown to black spots without any surrounding chlorosis or tan necrosis (resistant); 2 = Small dark brown to black spots with very little chlorosis or tan 240
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necrosis (moderately resistant); 3 = Small dark brown to black spots completely surrounded by a distinct chlorotic or tan necrotic ring, lesions generally not coalescing (moderately resistant to moderately susceptible); 4 = Small dark brown or black spots completely surrounded with chlorotic or tan necrotic zones; some of the lesions coalescing (moderately susceptible); 5 = The dark brown or black centres may or may not be distinguishable; most lesions consist of coalescing chlorotic or tan necrotic zones (Susceptible) (8). The results were analyzed statistically using SAS software (10) and means were compared using the least significant difference (LSD) test at P = 0.05. After 10 days of inoculation, symptoms of tan spot on wheat leaves
were observed and were registered based on the rating scale mentioned above. Fig. 2 showed that tan spot ratings recorded ranged from 1 to 4 indicating variable degrees of disease severity on wheat leaves. Reactions of wheat varieties to tan spot were quite similar with a slight difference for Nasr variety on which smallest lesions were observed for the majority of the cases (severity degree 1-2 over the 0-5 scale). More severe symptoms were recorded on the variety Salim (severity degrees 1-3) followed by Maali, Karim, and Razzak (Fig. 2). The populations P1 and P6 were the most aggressive (severity degree3 over the 0-5 scale). The less aggressive population was P5 (severity degree 1), while P2, P3 and P4 populations showed intermediate aggressiveness (Fig. 2).
Fig. 2. Reactions of wheat varieties to inoculation with Pyrenophora tritici-repentis populations
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__________________________________________________________________________ RESUME Tissaoui S., Kamel S., Mougou-Hamdane A., Chérif M. et Nasraoui B. 2016. Réaction de cinq variétés tunisiennes de blé dur vis-à-vis de quelques populations de Pyrenophora tritici-repentis collectées de différentes origines géographiques. Tunisian Journal of Plant Protection 11: 239-243. Cette étude préliminaire vise à évaluer la réaction de cinq variétés tunisiennes de blé dur vis-à-vis de six populations de Pyrenophora tritici-repentis, agent causal de l’helminthosporiose ou taches bronzées, collectés de différentes régions du nord tunisien. Des plantules de blé dur cultivées en chambre de culture ont été inoculées par pulvérisation foliaire d’une suspension de Ptr. La réaction des variétés de blé a été évaluée 10 jours après l’inoculation sur la base de la sévérité des nécroses et/ou chloroses sur les feuilles. Cette évaluation a révélé des symptômes d’intensité variable selon les plants de blé, avec les populations 1 et 6 trois fois plus agressives que la population 5. Le comportement des variétés était assez similaire, cependant Salim suivi de Maali étaient les variétés les plus sensibles et Nasr relativement le plus résistant. Mots clés: Blé dur, population, Pyrenophora tritici-repentis, réaction, variété
__________________________________________________________________________ ملخص تقييم لردة فعل خمسة.2016 ،حمدان وماجدة الشريف وبوزيد نصراوي- سلمى وسناء كمال وأميرة موقو،تيساوي مجمعةPyrenophora tritici-repentis القاسي تجاه بعض مجتمعات من فطر/أصناف تونسية من القمح الصلب Tunisian Journal of Plant Protection 11: 239-243. .من مناطق جغرافية مختلفة Pyrenophora اهتمت هذه الدراسة األولية بتقييم ردة فعل خمسة أصناف من القمح الصلب تجاه ستة مجتمعات للفطر تم إمراض بادرات. تم تجميعها من مناطق مختلفة بالشمال التونسي، المسبب لمرض التبقع البرنزيtritici-repentis أيام من عملية10 تم تقييم ردة فعل بادرات القمح بعد.قمح مزروعة داخل بيت مكيف برش أوراقها بمعلّق الفطر أظهر هذا التقييم أعراضا مختلفة الحدة على بادرات القمح كان.أو اصفرار األوراق/اإلمراض باالعتماد عل شدة نخر و ولكن كان، وكان سلوك أصناف القمح متشابه تقريبا.5 ثالث مرات أكثر عدوانية من المجتمع6 و1 فيها المجتمعان .الصنف "سليم" متبوعا بالصنف "معالي" األكثر حساسية والصنف "نصر" نسبيا األكثر مقاومة Pyrenophora tritici-repentis ، مجتمع،قاسي/ قمح صلب، صنف، ردة فعل:كلمات مفتاحية __________________________________________________________________________ LITERATURE CITED 1. Andonova, R. and Todorova, M. 2007. In vitro Characteristics of different Pyrenophora triticirepentisisolates.Bulg. J. Agric. Sci. 13: 673678. 2. Andrie, R.M., Pandelova, I., and Ciuffetti, L.M. 2007. A combination of phenotypic and genotypic characterization strengthens Pyrenophora tritici-repentis race identification. Phytopathology 97:694-701. 3. Benslimane,H., Lamari, L., Benbelkacem, A.,Sayoud, R., and Bouznad, Z., 2011. Distribution of races of Pyrenophora triticirepentisin Algeria and identification of a new virulence type. Phytopathol. Medit. 50: 2032011. 4. Benslimane, H., Labidi, S., Yahyaoui A., Ogbonnaya, F., Bouznad, Z., and Baum, M. Tunisian Journal of Plant Protection
2013. Genetic diversity of Pyrenophora triticirepentis in Algeria as revealed by amplified fragment length polymorphism (AFLP) analysis. Afr. J. Biotechnol. 12: 4082-4093. 5. Ciuffetti, L.M. and Tuori, R.P. 1999. Advances in the characterization of the Pyrenophora triticirepentis-wheat interaction. Phytopathology 89: 444-449. 6. Gilchrist, S.L., Fuentes, F., and Isla de Bauer, M.L. 1984. Determinacion de Fuentes de Resistencia contra Helminthosporiumtriticirepentisbajoconditiones de campo e inernadero. Agrocienca56: 95-105. 7. Krupinsky, J.M. 1992. Aggressiveness of Pyrenophora tritici-repentis isolated from grass and barley hosts. Plant Dis. 76: 783-789. 242
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8. Lamari, L. and Bernier, C.C. 1989. Evaluation of wheat lines and cultivars to tan spot [Pyrenophora tritici-repentis] based on lesion type. Can. J. Plant Pathol.11: 49-56. 9. Moreno, M.V., Stenglein, S.A., Balatti, P.A., and Perelló, A.E. 2008. Pathogenic and molecular variability among isolates of Pyrenophora tritici-repentis, causal agent of tan spot of wheat in Argentina. Eur. J. Plant Pathol. 122: 239-252.
10. Raymond, P.J., Bockus, W.W., and Norman, B.L. 1985. Tan Spot of winter wheat: Procedures to determine host response. Phytopathology 75: 686-690. 11. Singh, S., Bockus, W.W., Sharma, I., and Bowden, R.L. 2008. A novel source of resistance in wheat to Pyrenophora triticirepentisrace 1. Plant Dis. 92: 91-95.
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