بررسی کارآیی ژن‌های مقاومت نسبت به puccinia graminis f.sp. tritici عامل بیماری زنگ سیاه گندم در استان اردبیل

عامل بیماری زنگ سیاه گندم (puccinia graminis f.sp. tritici) یکی از بیماری‌های مهم گندم در ایران است که خسارت سنگینی را در سال‌های شیوع بیماری می‌ تواند وارد نماید. در چند سال اخیر نژادی از قارچ عامل بیماری به نام ug99 و تغییر یافته‌ های آن ظهور یافته است که روی گیاهان حامل اغلب ژن‌های مقاومت موجود در ارقام تجاری گندم، بیماری‌زا می‌باشند. با توجه به این که این ژن‌ها در منابع مقاومت به  ug99به‌طور وسیع در مناطق گندم‌کاری ایران استفاده می‌گردد، لازم است وضعیت تغییرات ژنتیکی این قارچ به‌طور مداوم بررسی شود تا از ارقام مقاوم مناسب استفاده گردد. برای این منظور 56 لاین افتراقی که از کشور کانادا تهیه شده بود، در مزرعه و تحت شرایط طبیعی در استان اردبیل هر لاین در دو ردیف یک متری در فصل پاییز کشت شدند و هر ده روز یک بار پای بوته‌ها به طریق غرقابی آبیاری شد تا شرایط بهینه برای توسعه بیماری مهیا گردد. مطابق با نتایج، در هر دو سال بیماری به خوبی در خزانه مستقر شد. گیاهان حامل ژن srmcn حساس‌ترین ژن نسبت به زنگ سیاه گندم بود و بقیه گیاهان حامل ژن‌های نیمه مقاوم تا حساس بودند. در سال دوم نیز بیماری بخوبی ظاهر شد. گیاهان حامل ژن‌های srmcn، sr9h و sr42 حساس‌ترین ژن‌ها بودند، اما گیاهان حامل ژن‌ های sr24 وsr47  مقاوم بودند که برای ایجاد ارقام مقاوم به زنگ سیاه در ایران توصیه می ‌گردند. هم‌چنین از گیاهان حامل ژن‌های sr31،sr26  ، sr27 و sr28 که مقاومت نسبتاً خوبی نسبت به زنگ سیاه داشتند می ‌توان در ترکیب با ژن‌های sr24 وsr47  در تولید ارقام مقاوم به زنگ سیاه استفاده نمود.

Evaluating efficacy of resistance genes to Puccinia Graminis f.sp. Tritici, as the cause of wheat stem rust disease in Ardabil province (Northwestern Iran)

Background and Objectives The stem rust of wheat (Puccinia graminis f.sp. tritici) is one of the most important diseases of wheat in Iran causing severe yield loss in some years in the case of favourable condition for disease epidemic. In the recent years, a new race of stem rust (Ug99) and its new variants have been emerged, which are virulent on most resistance genes, such as Sr31, Sr38, etc., and have potential to spread rapidly and cause severe yield loss. The Ug99 race was first reported in 2009 from Lorestan and Hamadan provinces of Iran.Materials and MethodsResults of a recent study conducted during 20112013 in Iran showed virulence on Sr36, Sr38, SrMcN and SrTmp genes and since, these genes have been used widely in genotypes resistant to Ug 99, there is a possibility of breakdown of these genes in Iran. Therefore, genetic variability of pathogen should be continuously investigated and resistance sources should be developed based on this information. For achieving this aim, 56 stem rust differential cultivars/lines obtained from the Cereal Research Center, Manitoba State, in Canada were planted in Ardabil Province, northwestern Iran under natural field conditions. The seeds of each cultivar/line were planted in two rows with 1 m of length and were irrigated every 10 days to promote disease development. Disease severity and type of infection of each cultivar/line were recorded based on the standard protocol at late flowering stage.Results and DiscussionIn the first year, the disease was developed only in Ardabil region. The SrMcN gene was the most susceptible gene, however, there was no virulence on Sr5, Sr21, Sr9e, Sr7b, Sr11, Sr6, Sr36, Sr9b, Sr30, Sr9a, Sr9d, Sr24, Sr31, Sr38, Sr8b, Sr9h, Sr12, Sr16, Sr19, Sr20, Sr22, Sr26, Sr27, Sr28, Sr32, Sr37, Sr39, Sr40, Sr41, Sr42, Sr43, Sr44, Sr45, Sr47, Sr50 ,and Sr53 genes. Other genes were moderately susceptible to virulence. In the second year, the disease was also developed.  SrMcN, Sr9h, and Sr42 genes were the most susceptible genes. However, no virulence was observed on Sr24 and Sr47 genes. The genes of Sr31 and Sr36 were resistant and susceptible, respectively. It seems that Sr36 and Sr38 genes have no potential to be used in breeding for achieving resistance against stem rust disease in Iran. However, Sr24 and Sr47 genes, which were resistant in the study area, are recommended to be incorporated in breeding wheat for obtaining resistance against stem rust disease. In addition, Sr31, Sr26, Sr27, and Sr28 genes, which were relatively resistant in most areas, were found to have potential to be combined with Sr24 and Sr47 genes in wheat breeding programs.