Mining European winter wheat for leaf rust resistance in North India

Leaf rust caused by Puccinia triticina (Pt) is one of the most dangerous diseases of wheat and has led to significant yield losses worldwide. Due to the constant evolution of pathogen population, the resistance often breaksdown. Therefore, to match the pathogen evolution, extensive research is needed to widen the gene pool and for gene pyramiding. In this context, the present study was aimed to identify and characterize leaf rust resistance genes from the European winter wheat collection using the two most prevalent Pt pathotypes (77-5 and 77-9). Race-specific seedling assays and field evaluation were carried out at two different hot spot locations (Ludhiana and Langroya) in Punjab, India. Based on seedling response against each pathotype the germplasm was categorized into resistant (Infection type (IT)<3) and susceptible (IT >3). Out of 374 lines, 14 and 7 lines were resistant against pathotypes 77-9 and 77-5, respectively and 6 lines viz. Grisby, Hamac, Mandub, Timber, Tulsa and Winnetou showed resistance reactions against both the pathotypes. Under field conditions, 6 lines (Grisby, Hamac, Mandub, Timber, Tulsa, and Winnetou) showed highly resistant responses (AUDPC=0) at both the test locations, i.e. has showed all-stage resistance. Some of the lines showed adult plant resistance (AUDPC=1-200) as these were susceptible at the seedling stage. The identification of Lr genes present in these lines was done by using differentials and molecular markers tagged with effective Lr genes under North-Indian conditions. A total of eight Lr genes tagged markers (Lr9, Lr19, Lr24, Lr28, Lr37, Lr42, Lr58 and Lr76) were used. The presence of Lr19, Lr24, Lr28, Lr58 and Lr76 was confirmed. The resistant germplasm identified can be deployed in leaf rust resistance breeding programs to broaden the genetic basis of leaf rust resistance.