مهار زیستی نماتد ریشه گرهی گوجه فرنگی (meloidogyne javanica) به وسیله برخی قارچ های آنتاگونیست

نماتد عامل ریشه گرهی meloidogyne javanica به عنوان یکی از مهم ترین نماتدهای مخرب گیاهی در سطح جهان محسوب می شود. به دلیل مضرات ناشی از مصرف سموم شیمیایی در سلامت انسان و محیط زیست، استفاده از روش های مهار زیستی خصوصاً قارچ های آنتاگونیست که توانایی تولید برخی از آنزیم های مخرب نماتدها را داشته باشند می تواند به عنوان روشی جایگزین و مناسب برای کنترل این بیماری در نظر گرفته شود. پژوهش حاضر با هدف ارزیابی اثر آنتاگونیستی برخی جدایه ‎های قارچی روی نماتد ریشه گرهی گوجه فرنگی در شرایط آزمایشگاهی و گلخانه‎ ای انجام گرفت. ارزیابی در شرایط آزمایشگاه به صورت توانایی تولید آنزیم لیپاز و محاسبه درصد تخم پارازیته شده در تقابل نماتد بیمارگر-قارچ آنتاگونیست و همچنین در شرایط گلخانه به صورت بررسی فاکتورهای رشدی گوجه فرنگی شامل: صفات ریخت‌شناسی (طول ریشه، وزن‎ تر و خشک ریشه، وزن‎ تر و خشک اندام‎های هوایی، تعداد انشعابات ساقه، ارتفاع بوته)، صفات عملکردی (تعداد میوه و وزن میوه در بوته) و صفات تکثیری نماتد (شاخص گال نماتد و تعداد تخم در کیسه تخم) تحت تاثیر جدایه های قارچی انجام شد. نتایج داده ها در شرایط آزمایشگاه نشان داد گونه ی قارچی trichoderma atroviride در پنج روز متوالی اندازه گیری فعالیت ویژه آنزیم، دارای بیشترین مقدار تولید آنزیم لیپاز و همچنین بیشترین تعداد تخم پارازیته شده و کمترین تولید آنزیم لیپاز و تعداد تخم پارازیته شده مربوط به جدایه های قارچی ulocladium dauci و alternaria alternata بود. در شرایط گلخانه نیز قارچ t. atroviride در قیاس با شاهد آلوده به ترتیب با افزایش 95، 61/3 و 99/4 درصدی در طول ریشه، وزن تر و وزن خشک ریشه، با افزایش دو برابری در ارتفاع بوته نسبت به شاهد، افزایش دو برابری در وزن تر و خشک اندام‌های هوایی بوته و 47/8 درصد افزایش در تعداد ساقه، افزایش 45/4 درصدی در وزن میوه و افزایش دو برابری در تعداد میوه گوجه‌فرنگی نسبت به شاهد و همچنین به ترتیب با کاهش 41/8 و 48/8 درصد در جمعیت گال نماتد و تعداد تخم نماتد در بوته، دارای بالاترین اثر آنتاگونیستی علیه نماتد عامل ریشه گرهی بود و به عنوان موفق‎ترین جدایه‎ ی قارچی و جدایه های u. dauci و a. alternata به عنوان کم اثرترین جدایه ها در کاهش خسارت ناشی از نماتد ریشه‎ گرهی گوجه فرنگی معرفی می گردند.

biological control of tomato root knot nematode (meloidogyne javanica) by some antagonistic fungi

extended abstract 1.    introduction: the root-knot nematodes (meloidogyne spp.), are considered one of the most important plant-damaging nematodes in the world. in the last two decades, with the increasing prohibition of nematicides, the development of biological control agents has become one of the urgent needs to reduce the damage caused by these nematodes. considering the fresh consumption of tomato and the dangers caused by the residual chemical pesticides in this product and the adverse effects of toxins on human health and the environment, the use of biological control methods, especially nematode antagonist fungi, which can produce some destructive enzymes of nematodes can be considered as an alternative and suitable method to control this diseases. the present study was conducted to evaluate the antagonistic effect of some fungal isolates on the root-knot nematode in vitro and in greenhouse conditions. the evaluation was done in vitro as the ability to produce lipase enzyme and to calculate the percentage of parasitized eggs, also in greenhouse as the examination of tomato growth factors under the influence of fungal isolates on nematodes in pot the results in vitro conditions showed that trichoderma atroviride had the highest amount of lipase enzyme production and also the highest number of parasitized eggs. in greenhouse too, t. atroviride isolate had the highest antagonistic effect on tomato root-knot nematode and was introduced as the most successful fungal isolate in reducing damage caused by meloidogyne javanica.2.    materials and methods: to take samples of crops infected with nematodes, in may, june, and july 2019, plant and soil samples were taken from tomato farms and greenhouses in kermanshah city. this study has tried to examine the antagonistic ability of seven isolates of five fungal genera including fusarium solani, f. oxysporum, f. equiseti, paecilomyces sp. trichoderma atroviride, ulocladium dauci, and alternaria alternata on knot-producing nematode in vitro and in greenhouse conditions. the ability of the lipase enzyme production of fungal isolates was also evaluated. the lipase specific activity assay in seven isolates of various species of fungi obtained from infected knot-producing nematode over five days of fungal growth (24, 48, 72, 96, and 120 h) was measured. also, evaluation was performed in vitro by calculating the percentage of parasitized eggs in a water-agar and the greenhouse by examining the growth factors of tomato under the antagonistic effect of fungal isolates on nematodes. the ability of antagonistic activity of the fungi on the eggs was evaluated in water-agar medium with an evaluation of the interaction between fungi and eggs. the numbers of healthy and parasitized eggs were calculated after two weeks. the ability of the antagonistic fungi under greenhouse conditions was studied. to provide fungal inoculum, 20g of soaked wheat seed were cast in bags with autoclave capability. per every gram of casted seed, 2 ml distilled water were added and during 24 hours they autoclaved 3 times. then to every of bag number of 4 fungi disks with 5 mm diameter from selected isolates was added in 3 repetitions and was kept at 25 °c and dark conditions. to colonize all of the seeds and to avoid hanging them, every 48 hours interval the seeds in bags were mixed. after three weeks all of the seeds were infected with fungal isolates. the ability of the antagonistic fungi under greenhouse conditions was done by adding fungal inoculum and the numbers of 2000 eggs to each pot and evaluation of performance traits of tomato in pot after 50 days. in every two conditions, data analysis anova (analysis of variance) was conducted using of the sas software version 9.4 in a completely randomized design (crd) with three replicates.3.    results and discussion: analysis of variance of evaluation results in vitro and greenhouse conditions showed significant differences among isolates in 1% level. the results of the data in vitro conditions showed that t. atroviride had the highest amount of lipase enzyme production and the highest number of parasitized eggs in five consecutive days of measuring specific enzyme activity, while the lowest lipase enzyme production and number of parasitized eggs were related to u. dauci and a. alternata. in greenhouse conditions, t. atroviride had the highest antagonistic effect against root-knot nematode, with 95%, 61.3%, 99.4%, 47.8% and 45.4% increase root length, fresh weight root, dry weight root, number of stem bifurcations and number of fruit compared to the control, respectively. also the results showed a twofold increase in plant height, fresh weight shoot and dry weight shoot. there was 41.8% and 48.8% decrease in number of node and the number of eggs per plant, too. 4.    conclusions: results showed there is direct relationship between an increase in plant yield and the addition of fungal isolates to the pot. the results of the antagonistic ability of fungal isolates in vitro and in greenhouse showed there is good correlation between the two conditions. so the results showed a positive effect of the fungal isolates in reducing nematode damage. finally, based on all of the evaluations t. atroviride was reported as the most effective isolate ana a. alternata and u. dauci isolates as the least effective antagonist fungi.