Protoplast fusion enhances antagonistic activity in Trichoderma spp

Abstract: Genus Trichoderma is one of the most important filamentous fungi used as a biocontrol agent. Because of the absence of sexual reproduction in this fungus, other methods of genetic improvement have been developed such as proptoplast fusion to enhance its bicontrol potential. Therefore the objectives of this study were; 1) protoplast fusion and regeneration of two fungicide tolerant mutants of Trichoderma viride and T. harzianum 2) using ISSR for fingerprinting of inter-specific protoplast fusants and 3) assessment of antagonistic ability of Trichoderma fusants against three soil born diseases. Protoplast was isolated from two fungicide tolerant mutants PTv-V and PTz-F of Trichoderma,. The frequency of fusion tolerant to both pesticides was about 0.3 % and eight fusants were selected for further studies. In fusant stability experiments, only five of these fusants were the result of nuclear fusion of parental cells. Molecular characterization of two stable fusants using ISSR indicated the presence of novel fragments which may be due to recombination events between parents. In dual culture biocontrol experiments, five selected fusants showed growth inhibition against three pathogens namely; Rhizoctonia solani, Fusarium oxysporum and Pythium ultimum.. However, Fus 7 indicated the best ability of inhibition the growth of the three pathogens. In greenhouse experiments Fus 7 demonstrated a great ability to reduce tomato damping off of the three pathogens in the presence of the two fungicides understudy. It was concluded that, the protoplast fusion is a powerful tool to enhance the biocontrol ability of Trichoderma sp. against diseases

دراسات وراثية على ذراري الإشريكية القولونية المعزولة من حالات التهاب الضرع في الأبقار

This study was carried out on 53 milk samples positive for California Mastitis Test taken from eight herds infected with clinical mastitis in Taif City. Mean Somatic cell Count (SCC) was 4, 482, 000 cells / ml. Forty-eight (51.06%) E .coli strains were isolated from bovine mastitic milk by bacteriological methods. From these E .coli strains, 27 were characterized with regard to their serotype and their DNA polymorphism pattern with REP and ERIC primers, special attention was given to recurrent E .coli mastitis in cows . For studying the epidemiology of clinical E . coli mastitis, the combination of serotype and DNA pattern detected , was used in this investigation .It was assured that the PCR reaction with the ERIC primers can be used in the field of E. coli strains identification. Based on the DNA polymorphisms patterns of E. coli isolates from clinical mastitic cows , it revealed that isolates have a great variations in regard to their genotypes. During the same lactation period, it was detected more than one clinical mastitis case associated with E . coli, but this clinical mastitic occurrence was irregularly. Whatever the occurrence, at this rate, E . coli strains isolated from the separate episodes of inflammation, were for the most part, of the same serotype and had the same DNA amplification pattern. Therefore, the PCR DNA amplification method can not replace serotyping in epidemiological studies .أجريت الدراسة على 53 عينة حليب كانت موجبة في اختبار كاليفورنيا، جمعت من ثمانية قطعان أبقار مخموجة بالتهاب الفرع الريوي في محافظة الطانف .كان متوسط تعداد الخلايا ( الكريات البيضاء ) 4,482,000 خلية في كل مل من الحليب عزلت 48 ذرية( 51,06 ٠/٠ ) من ذراري الإشريكية القولونية من حليب الأبقار المخموجة بالتهاب الضرع، وذلك باستخدام الطرائق الجرثومية من بين تلك الذراري؛ ميزت 27 ذرية إلى أنماطها المصلية وأنماطها الجينية ( طرز تغدد أشكال الـ دنا) ، وذلك عن طريق تكبير أو تضخيم الـ دنا بواسطة الحروف التكرارية الطردية العكسية القراءة( REP) ، والحروف التكرارية التوافقية (ERIC) هذا وقد عني البحث عناية خامة بالتهاب الضرع البقري المتسبب بالإشريكية القولونية المتكرر دوريا. ومن أجل دراسة وبيئات التهاب الضرع السريري الناتج عن خمج الاشريكية القولونية؛ استخدم ما يسمى بـ توافقية النمط المصلي وطراز الـ دنا للجرثومة السابقة المكتشفة في البحث. لقد أكد البحث أن تفاعل البوليميراز السلسلي (PCR) إضافة للحروف التكرارية التوافقية (ERIC) ، يمكن أن يستعمل من أجل التعرف على ذراري الإشريكية القولونية وتحديد هويتها .وبناء على طرز تمدد أشكال الـ دنا لعزولات الإشريكية القولونية المكتشفة في الأبقار المخموجة بالتهاب الضرع، تين ان للعزولات أشكال مختلفة أو متغيرة في ما يتعلق بأنماطها الجينية. وخلال فترة در اللبن ذاتها؛ اكتشفت أكثر من حالة التهاب ضرع مريري تسببت بوساطة الإشريكية القولونية؛ ولكن وقوع هذا الالتهاب لم يكن على نحو منتظم . وأيا كان الوقوع المرضي؛ والحالة هذه ؛ فان ذراري الإشريكية القولونية المعزولة من الحالات العارضة لالتهاب الضرع؛ كانت - في أغلب الأحوال - من النمط المصلي ذاته، كما كان لها طراز تفخم الـ دنا ذاته أيضأ

Mission archéologique de Madâ'in Sâlih (Arabie Saoudite) : Recherches menées de 2001 à 2003 dans l'ancienne Hijrâ des Nabatéens

84 pagesInternational audienceThis contribution presents the preliminary results of the Madâ'in Sâlih archaeological project, which started in 2001 and which, in December 2004, completed its fourth field season. The aims of this five-year project are a systematic recording of the archaeological remains at the site as well as an analysis of its agricultural potential. The former include not only the tombs, sanctuaries, wells, quarries, walls, buildings, etc., but also the inscriptions written in various scripts and languages. Parallel to this exploration of what is visible on the surface, an extensive geophysical survey was undertaken in the so-called residential area, in the central part of the site, in order to obtain an image of the sub-surface remains. This contribution begins with a presentation of the sources, followed by a brief history of the exploration of Madâ'in Sâlih. The focus is on the conditions which allowed this project to be established as well as the problematics which guided it. J.-B. Rigot then presents his analysis of the agricultural potential of the site, demonstrating the existence, in antiquity, of a large oasis. Finally, a preliminary description of the main components of the sites: the necropoleis, the sanctuaries and the residential area, is given