شناسایی نژادهای فیزیولوژیک عامل بیماری سفیدک کرکی آفتابگردان (Plasmopara halstedii) و واکنش ژنوتیپ‌های میزبان به آن نژادها در شرایط کنترل شده

نویسنده

مؤسسه تحقیقات اصلاح و تهیه نهال و بذر، کرج

چکیده

به منظور شناسایی نژادهای فیزیولوژیک عامل بیماری سفیدک کرکی آفتابگردان در ایران، نمونه‌های قارچ عامل بیماری جمع‌آوری و پس از احیا روی رقم حساس رکورد تکثیر شدند. به منظور تعیین نژادهای فیزیولوژیک قارچ عامل بیماری جدایه‌های نماینده مناطق روی ارقام افتراقی استاندارد مایه‌زنی شدند. با توجه به یکسان بودن بیماریزایی جدایه‌های آزمایش شده و شناسایی نژاد 100 برای آن‌ها، تعداد 77 ژنوتیپ آفتابگردان شامل هیبریدهای جدید، لاین‌های برگشت دهندۀ باروری و نرعقیم سیتوپلاسمی، تک بوته‌های انتخابی و جوامع انتخابی ارقام آزاد گرده‌افشان در مقابل نژاد شناسایی شده در شرایط آزمایشگاهی و گلخانه‌ای مورد ارزیابی قرار گرفتند. میزان آلودگی بوته‌ها پانزده روز پس از مایه‌زنی و بر اساس صفات ظاهری بیماری شامل مرگ گیاهچه، اسپورزایی روی کوتیلدون‌ها، اسپورزایی در کوتیلدون و برگ‌های اصلی، کوتولگی، موزائیک، رنگ پریدگی و بد شکلی ارزیابی شد. با توجه به اهمیت این علایم و نقش آن‌ها در شدت بیماری برای هر کدام امتیازی منظور و میانگین مجموع امتیازات هر ژنوتیپ به عنوان شاخص شدت بیماری (Disease Severity Index :DSI) برای تعیین واکنش لاین‌های آفتابگردان استفاده شد. بر اساس نتایج به دست آمده 64 ژنوتیپ به عنوان مقاوم (20>DSI>0)، و بقیه به عنوان نیمه مقاوم ، نیمه حساس، حساس و خیلی حساس ارزیابی شدند.

کلیدواژه‌ها


عنوان مقاله [English]

Identification of Sunflower Downy Mildew (Plasmopara halstedii) Physiological Races and Reaction of the Host Genotypes to the Races Under Controlled Conditions

نویسنده [English]

  • S. Rahmanpour
چکیده [English]

The soil samples containing the pathogen, Plasmopara halstedii, were collected, refreshed and mass-produced on susceptible cultivar Record, using whole seedling immersion method. The isolates were inoculated on standard differential lines to investigate the physiological races. Using the dominant race (race 100) of the pathogen in sunflower planting areas, 77 new Iranian sunflower genotypes including hybrids, restorer lines, CMS lines and individuals were evaluated against the disease under controlled conditions. Fifteen days post inoculation, the treated plants were evaluated based on six qualitative disease characteristics including damping-off, sporulation on cotyledons, sporulation on leaves and cotyledons, stunt, leaf mosaic or chlorosis and deformation. They were then converted to quantitative means based on their importance in disease development. Finally the average of the means as disease severity index (DSI) was used for evaluations. Based on the results, 64 genotypes were categorized as resistant and the rest were identified as moderately resistant, moderately susceptible, susceptible, and highly susceptible.

کلیدواژه‌ها [English]

  • Sunflower
  • Plasmopara halstedii
  • Disease severity index
  • resistance
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