تنوع فنوتيپي جدايه‌هايMacrophomina phaseolina و ارتباط آن با بيماري‌زايي

PHENOTYPIC DIVERSITY AMONG ISOLATES OF Macrophomina phaseolina AND ITS RELATION TO PATHOGENICITY

شصت جدايه Macrophomina phaseolina عامل پوسيدگي زغالي از مناطق مختلف ايران جدا شده از گياهان طالبي، خربزه، سويا، خيار، رزماري و كنجد مورد استفاده قرار گرفت. خصوصيات فنوتيپي آنها روي PDA در دماي 35 درجه سلسيوس مقايسه شد. ظاهر پرگنه، رشد، ميزان توليد سختينه و همچنين ارتباط بين رشد در دماي 35 درجه سلسيوس و اندازه سختينه تعيين گرديد و در مطالعات گلخانه‌اي سختينه فنوتيپ‌هاي مختلف توليد و با خاك مخلوط گرديد و با استفاده از گياهچه‌هاي سويا و طالبي بيماري‌زايي جدايه‌ها تعيين شد. ميزان كلونيزاسيون ريشه‌ها پس از هشت هفته با كشت قطعات ريشه روي PDA محاسبه گرديد. تمام تيمارها در يك طرح بلوك‌هاي تصادفي در گلخانه با دماي 28-35 درجه سلسيوس انجام گرديد و با استفاده ازنرم افزار SPSS آناليز صورت گرفت. جدايه‌ها در چهار گروه شامل پنبه‌اي با سختينه زياد، پنبه‌اي با سختينه كم، تقريباً و كاملاً تخت تقسيم گرديد.جدايه‌هاي پنبه‌اي با سختينه كم قادر به كلونيزه كردن ريشه‌هاي سويا و طالبي نبودند ولي اختلاف معني‌داري بين ساير فنوتيپ‌ها در كلونيزه كردن گياهان فوق ديده نشد.

Sixty isolates of Macrophomina phaseolina, the cause of charcoal rot, were isolated from different parts of Iran on various plants including cantaloupe, long melon, soybean, cucumber, apricot, rosemary and sesame. Phenotypic characteristics of the isolates were compared by growing on PDA at 35°C. Colony appearance, growth rate, production and amount of sclerotia and also the relationship between growth rate at 35°C and size of sclerotia were determined. In a greenhouse study, sclerotia of different phenotypes were mixed with the soil and soybean and cantaloupe plants were used for pathogenicity tests. After eight weeks root colonization was assessed. All treatments were arranged in a randomized complete block design with three replications. The data were analyzed using SPSS software. Isolates were grouped in four phenotypes: fluffy with abundant sclerotia, fluffy with few sclerotia, partially fluffy, and appressed growth. There was a significant difference between fluffy with few sclerotia and other phenotypes. Fluffy isolates with few sclerotia could not colonize soybean and cantaloupe roots. No significant differences were observed among other phenotypes on colonizing cantaloupe and soybean roots.