Genetics of Partial Resistance to Leaf Rust (Puccinia triticina) in Bread Wheat (Triticum aestivum)

Abstract

The genetics of partial resistance to leaf rust (Puccinia triticina Erikss. & Henn.) in bread wheat (Triticum aestivum L. em Thell) was investigated in a nine-parent diallel (excluding reciprocals) using area under disease progress curve (AUDPC) and final disease severity (FDS) in the F1 and F2 generations. Test material consisted of slow rusting and susceptible lines. The Vr–Wr graphs exhibited partial dominance for FDS and complete dominance for AUDPC (F1 and F2 generations). Parents CPAN1796, HD2329, NW1014 and MACS2496 had preponderance of minor genes for partial resistance, whereas susceptible parents SONALIKA and HS1138-6-4 showed the absence of minor genes for both AUDPC and FDS (F1 and F2 generations). Variations due to additive and dominance genetic variances were significant for both AUDPC and FDS (F1 and F2 generations). The estimate of 1–3 minor gene(s) in the slow rusting parents may be responsible for race non-specific adult plant resistance. Since narrow-sense heritability for both AUDPC and FDS was moderate in both F1 and F2, success in selecting desirable lines with partial resistance to leaf rust in early segregating generations can easily be achieved. The parents CPAN1796, NW1014, HD2329, PBW373 and RAJ3077 with low AUDPC and FDS having partial resistance either due to Lr34 and/or minor genes were identified as good general combiners. The parents identified in the study can be used in breeding program for developing high-yielding cultivars with durable leaf rust resistance.