Components of resistance to rust disease in lentil: Implications for breeding

Abstract

Lentil ( Lens culinaris Medik.) is an important pulse crop worldwide, but its productivity is severely threatened by rust caused by Uromyces viciae‐fabae , making the identification and deployment of resistant genotypes essential for sustainable production. In the present study, a diverse set of lentil lines was screened under natural epiphytotic conditions at Gurdaspur, India, during the 2023–2024 and 2024–2025 winter seasons to evaluate disease reaction and infection type. A subset of 43 lines exhibiting diverse resistance responses in 2023–2024 was further assessed under artificial conditions to analyze resistance components, including latent period (LP50), pustule density, uredial and aecial pustule size, rust severity, infection efficiency (IE), and apparent infection rate. Six lines, namely, DKL 37‐7, DKL 13‐2‐2, EC 1–7, DKL 13‐4‐7, LL 1698, and Vipasha, exhibited immune reactions with no visible symptoms, whereas IC‐241249, DKL 13‐4‐9, DKL 13‐4‐5, EC 1–2, and EC 1–3 showed near‐immune resistance characterized by necrotic flecks. In addition, 36 lines displayed non‐hypersensitive reactions to rust. Significant genotypic variation was observed for all resistance components. LP50 showed strong negative correlations with IE ( r  = −0.84), uredial pustule size ( r  = −0.74), and spore count per pustule ( r  = −0.83), indicating its critical role in slowing disease development. This study not only identifies a novel set of immune and near‐immune lentil lines but also quantitatively dissects the components of partial resistance, highlighting LP50 as the most critical component of field resistance. The identified donors with known resistance types and knowledge of critical components of resistance are important for precision breeding.