A century of fighting wheat rusts in India- lessons learnt and future perspectives

Rusts also called as moving targets, are very devastating diseases of wheat. Epidemics of wheat rusts have been recorded since times immemorial. The landmark contribution of Dr. E. C. Stakman at Cereal Rust Laboratory, Minnesota, USA opened a new area that races occur in Puccinia graminis tritici. In India wheat rust research started in 1923 under the leadership of Dr. K. C. Mehta. His basic work on the identification of races in three wheat rust pathogens and epidemiology of wheat rusts have led to the foundation of a strong rust research programme in India. He proved it beyond doubt that alternate hosts are not functional under Indian situation. Dr. K. C. Mehta was working at the Agra College, Agra, Dr. R. Prasada provided a sound background support. Since then a number of Scientists have led the programme and made significant contributions. Now we identify the pathotypes on Near Isogenic Lines (NILs) using a binomial system of nomenclature and have a collection of more than 150 pathotypes of different rust pathogens. Information on the rust resistance of Indian wheat and barley material till today is available. Based on the gene matching technique and molecular markers, we are able to characterize rust resistance genes in all the wheat materials. To achieve durable rust resistance, we deploy a mosaic of wheat varieties carrying all time, adult and slow rusting resistance. The recommendation of wheat varieties is made based on the multi-location testing for field resistance to the region-specific rust diseases and pathotype distribution. There is a narrow diversity for stripe rust resistance in wheat and efforts are on to build it. Pyramiding of rust resistance genes has led to the registration of 63 genetic stocks of wheat and barley with NBPGR, New Delhi. The genomes of 21 pathotypes of three rust pathogens have been sequenced. Two new rust resistance genes in wheat; Lr80 and Sr65 (two of the eleven rust resistance genes designated by Indian researchers among the 235 designated internationally in the last 88 years), were designated from Flowerdale centre. Studies on doubled haploid production, epidemiology in changed situation, effectors, and molecular basis of pathogenesis were conducted. For the last 52 years, we had no rust epidemic on wheat. The system is now in place to combat any threat of wheat and barley rusts in India.