شناسايي پاتوتيپ هاي قارچ عامل زنگ قهوه اي گندم در استان هاي مازندران و گلستان

Identification of wheat leaf rust (Puccinia recondita f. sp. tritica)pathotypes in Mazandaran and Golestan provinces

Leaf rust is a potentially devastating disease of wheat that is basically controlled by use of resistant varieties. The fungus of wheat leaf rust Puccinia recondita Rob. ex Desm. f. sp. tritici Eriks. contains a variety of virulent races and errode resistant genes. To provide varieties resistant to leaf rust, it is essential to know which resistant genes will be effective against leaf rust pathotypes that occur where their varieties will be grown and then employ them in present wheat varieties. To identify pathotypes present in leaf rust population, twenty wheat leaf rust samples infected with Puccinia recondita f. sp. tritici were collected from different areas of Mazandaran and Golestan provinces and transfered to laboratory in 2003. After purification and spore multiplication, avirulence & virulence of cultures on 12 Thatcher near isogenic lines were determined by low & high infection types, respectively and eight different pathotypes were identified using system of designation of pathotypes of plant pathogens. Pathotype 5.5.0.7 collected from Sari- Mahdasht, carrying virulence on seven different Lr genes were found to he the most virulent pathotypes, while the pathotypes 5.0.0.5 and 4.1.4.4 collected from Ghaemshahr and Sari area with virulence on only four Lr genes were the weakest pathotype. Pathotype 4.1.4.5 carrying virulence on five different Lr genes and moderate virulence, with 40% of frequency were the most prevalent pathotype and was present in different areas of two provinces. In this study no virulence was found on Lr9, 24, 26 and Lr2a resistance genes but all isolates were virulent on Lr30 gene.