Multi-environment phenotyping to identify broad-based, stable resistance in wheat germplasms against leaf and stripe rust diseases

Globally, leaf and yellow rusts are considered one of the most serious biotic constraints of wheat inflicting huge economic losses in India. Host resistance is the only efficient, economical, eco-friendly way of controlling rust diseases. With this scenario, experiments were carried out to characterize the seedling and adult plant resistance in diverse wheat genotypes. By applying the gene-matching technique using multi-pathotype data, four Yr ( Yr A, Yr 2 , Yr 9 , Yr 18) and seven Lr ( Lr 2, Lr 10, Lr 13 , Lr 23 , Lr 24 , Lr 26 , Lr 34) genes in Indian wheat germplasm accessions and five Yr ( Yr A, Yr 2, Yr 9, Yr 18, Yr 27) and nine Lr ( Lr 1, Lr 3, Lr 10, Lr 13, Lr 19, Lr 23, Lr 24, Lr 26, Lr 34) genes in Indian wheat cultivars were characterized singly or combinations with other vital genes. Adult plant slow rusting resistance was assessed through host response and different epidemiological parameters. Promising adult plant slow rusting resistance against stripe and leaf rust was observed in different wheat genotypes consistently during the rabi seasons of 2018–19 and 2019–20. All these promising rust-resistant genotypes at the adult plant stage were susceptible at the seedling stage to one or more pathotype(s) including the most prevalent and virulent of both rusts, which indicated the presence of APR gene(s). All the epidemiological parameters were strongly and positively correlated in the study, for which we can strongly conclude that final disease severity, coefficient of infection, and relative area under the disease progress curve followed by infection rate are the most appropriate parameters to assess adult plant slow rusting resistance. The lines identified in this study are useful in the hybridization programs to enhance the levels of resistance.