بررسي كارآيي ژن‌هاي مقاومت نسبت به Puccinia graminis f.sp. tritici عامل بيماري زنگ سياه گندم در استان اردبيل

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

عامل بيماري زنگ سياه گندم (Puccinia graminis f.sp. tritici) يكي از بيماري‌هاي مهم گندم در ايران است كه خسارت سنگيني را در سال‌هاي شيوع بيماري مي‌­تواند وارد نمايد. در چند سال اخير نژادي از قارچ عامل بيماري به نام Ug99 و تغيير يافته‌­هاي آن ظهور يافته است كه روي گياهان حامل اغلب ژن‌هاي مقاومت موجود در ارقام تجاري گندم، بيماري‌زا مي‌باشند. با توجه به اين كه اين ژن‌ها در منابع مقاومت به Ug99به‌طور وسيع در مناطق گندم‌كاري ايران استفاده مي‌گردد، لازم است وضعيت تغييرات ژنتيكي اين قارچ به‌طور مداوم بررسي شود تا از ارقام مقاوم مناسب استفاده گردد. براي اين منظور 56 لاين افتراقي كه از كشور كانادا تهيه شده بود، در مزرعه و تحت شرايط طبيعي در استان اردبيل هر لاين در دو رديف يك متري در فصل پاييز كشت شدند و هر ده روز يك بار پاي بوته‌ها به طريق غرقابي آبياري شد تا شرايط بهينه براي توسعه بيماري مهيا گردد. مطابق با نتايج، در هر دو سال بيماري به خوبي در خزانه مستقر شد. گياهان حامل ژن SrMcN حساس‌ترين ژن نسبت به زنگ سياه گندم بود و بقيه گياهان حامل ژن‌هاي نيمه مقاوم تا حساس بودند. در سال دوم نيز بيماري بخوبي ظاهر شد. گياهان حامل ژن‌هاي SrMcN، Sr9h و Sr42 حساس‌ترين ژن‌ها بودند، اما گياهان حامل ژن‌­هاي Sr24 وSr47 مقاوم بودند كه براي ايجاد ارقام مقاوم به زنگ سياه در ايران توصيه مي­‌گردند. هم‌چنين از گياهان حامل ژن‌هاي Sr31،Sr26 ، Sr27 و Sr28 كه مقاومت نسبتاً خوبي نسبت به زنگ سياه داشتند مي­‌توان در تركيب با ژن‌هاي Sr24 وSr47 در توليد ارقام مقاوم به زنگ سياه استفاده نمود.

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 Methods Results of a recent study conducted during 2011-2013 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 Discussion In 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.