Characterization of five new pathotypes of Puccinia triticina identified from Northeast India, Nepal, and Bangladesh

Northeast India, Nepal, Bhutan, and Bangladesh form a continuum of 11.55 million hectare wheat growing area with similar production situations. Additionally, wheat cultivation in some of the traditional rice growing areas of far Northeast India has started only few years ago. To explore the virulence structure of Puccinia triticina , these areas were surveyed for the first time. Virulence analyses of P. triticina populations have revealed the occurrence of five new pathotypes in these areas. Pathotypes 20 − 1 (93R57 = NHKTL), 49 (93R49 = NHKTN), 52 − 3 (121R60 = MHKTN) were identified from Northeast India, 143 (61R47 = KHTPM) from Nepal and 10 − 1 (56R27 = SGJPN) from Bangladesh. These pathotypes are quite diverse in their virulence on leaf rust resistance genes. For identifying rust resistance sources, a set of 600 wheat lines containing predominant cultivars, pipeline material and Near Isogenic Lines (NILs), was evaluated at the seedling stage against the new and closely related previously documented pathotypes under greenhouse conditions. Seventy one wheat lines were resistant to all new pathotypes. Leaf rust resistance genes Lr1 , Lr3a , Lr10 , Lr11 , Lr14a, Lr15, Lr16 , Lr17 , Lr20, Lr23 , and Lr26 occurring in Indian wheat cultivars were ineffective to most of the new pathotypes. In contrast Lr9 , Lr19 , Lr24 , Lr25 , Lr28, Lr32 , Lr39, Lr45 , and Lr47 were effective against these pathotypes. Based on the 25 pairs of SSR primers, these pathotypes were found distinct and broadly categorized into two groups.