The rusts of wheat, caused by three species of Puccinia, are very devastating diseases and are major biotic constraints in efforts to sustain wheat production worldwide. Their capacity to spread aerially over long distances, rapid production of infectious uredospores, and abilities to evolve new pathotypes, makes the management of wheat pathogens a very challenging task. The development and deployment of resistant wheat varieties has proven to be the most economic, effective and efficient means of managing rust diseases. Rust resistance used in wheat improvement has included sources from the primary gene pool as well as from species distantly related to wheat. The 1BL/1RS translocation from cereal rye was used widely in wheat breeding, and for some time provided resistance to the wheat leaf rust, stripe rust, and stem rust pathogens conferred by genes Lr26, Yr9, and Sr31, respectively. However, the emergence of virulence for all three genes, and stripe rust resistance gene Yr27, has posed major threats to the cultivation of wheat globally. To overcome this threat, efforts are going on worldwide to monitor rust diseases, identify rust pathotypes, and to evaluate wheat germplasm for rust resistance. Anticipatory breeding and the responsible deployment of rust resistant cultivars have proven to be effective strategies to manage wheat rusts. Efforts are still however being made to decipher the recurrence of wheat rusts, their epidemiologies, and new genomic approaches are being used to break the yield barriers and manage biotic stresses such as the rusts. Efficient monitoring of pathotypes of Puccinia species on wheat, identification of resistance sources, pre-emptive breeding, and strategic deployment of rust resistant wheat cultivars have been the key factors to effective management of wheat rusts in India. The success in containing wheat rusts in India can be gauged by the fact that we had no wheat rust epiphytotic for nearly last five decades. This publication provides a comprehensive overview of the wheat rust research conducted in India.

Wheat is the second most cultivated cereal crop in the world and is an important crop in India. Leaf (brown) rust, caused by Puccinia triticina, was the most prevalent among the three rusts found in all the wheat-growing areas of India, Bhutan, and Nepal during 2016 to 2019. Leaf rust samples from wheat crops in these countries were pathotyped using the wheat differential genotypes and binomial Indian system of nomenclature. To facilitate international communication, each pathotype identified was also tested using the North American differentials. A total of 33 pathotypes were identified from 1,086 samples, including three new pathotypes: 61R47 (162-5 = KHTPM) and 93R49 (49 = NHKTN) from India and 93R57 (20-1 = NHKTN) from Nepal. Two pathotypes, 121R60-1 (77-9/52 = MHTKL) and 121R63-1 (77-5 = THTTM), accounted for 79.46% of the population. Virulence on Lr19 was identified in 0.27% of the samples from Nepal only. The proportion of pathotype 121R60-1 (77-9 = MHTKL) increased to 57.55% during these years. Virulence was not observed on Lr9, Lr24, Lr25, Lr28, Lr32, Lr39, Lr45, and Lr47 in the population of the Indian subcontinent. Eighteen polymorphic simple sequence repeat (SSR) primer pairs tested on the isolates amplified 48 alleles with an average of 2.66 alleles per primer pair. Based on SSR genotyping, these pathotypes could be grouped into two clades with another two subclades each. Many of the Lr genes present in Indian wheat germplasm (Lr1, Lr3a, Lr10, Lr11, Lr14a, Lr15, Lr16, Lr17, Lr20, Lr23, and Lr26) were ineffective for a majority of pathotypes. Most of these varieties possessed a high degree of leaf rust resistance. The field resistance of wheat varieties could be attributed to the interaction of genes, unknown resistance, or adult plant resistance.