Documentation of multi-pathotype durable resistance in exotic wheat genotypes to deadly stripe and leaf rust diseases

Leaf and yellow rusts are considered as one of the most serious biotic constraints of wheat inflicting massive economic losses globally. Host resistance is the only efficient, economical, ecofriendly way of controlling the rust diseases. Characterization of diverse wheat materials is always of a paramount importance for identifying potential varietal material to effectively control rusts and insignificant yield losses. With this background, the present experiments were designed and carried out at Wheat Rusts Multiplication and Phenotyping Facility, Wheat Pathology Experiment Farm and National Phytotron Facility of ICAR-IARI, New Delhi, and ICAR-IIWBR, Regional Station, Flowerdale, Shimla, for two consecutive years 2018-2019 and 2019-2020. Multi-environment phenotyping and characterization of stripe and leaf rust resistance were performed at both seedling stage in temperature-controlled growth chamber/greenhouse and adult plant stage in field conditions. By applying the gene-matching technique using multi-pathotypes data, five Yr (YrA, Yr2, Yr9, Yr18 and Yr27) and eight Lr (Lr1, Lr3, Lr10, Lr13, Lr19, Lr23, Lr26 and Lr34) genes in 98 exotic wheat genotypes (PG-Parent genetic pool, GS-Genomic selection genotype of CIMMYT-BISA, CIMCOG-CIMMYT Mexico core germplasm panel) were characterized singly or combinations with other vital genes. Adult plant slow rusting resistance was assessed through host response and different epidemiological parameters. All these promising rust-resistant genotypes at adult plant stage were susceptible at seedling stage to one or more pathotype(s), which indicated the presence of non-race-specific resistance gene(s). The lines identified could play pivotal role in the hybridization programs to enhance the resistance.