Gene-specific marker and trait-based evaluation of powdery mildew resistance in garden pea (Pisum sativum var Hortense L.)

Powdery mildew (PM), caused by Erysiphe pisi DC ex. Saint-Amans, poses a major constraint in pea cultivation, underscoring the identification of resistant genotypes for effective disease management. The current study employed in-vitro, in-vivo, and molecular screening methods to assess the PM reaction behaviour of 11 pea genotypes aiming to identify reliable resistance source. Field assessments during two crop growth phases were carried out at two locations namely Hawalbagh (Almora) and Mukteshwar (Nainital). Among the genotypes tested VP-2020-101 and VP- 2024-55 were categorised as resistant and showed the lowest disease severity at both locations, with significantly limited Disease Incidence (DI) and Percent Disease Index (PDI). These results were corroborated by detached leaf method assay conducted under polyhouse (spore proof chamber) and incubator conditions, where VP-2020-101 and VP- 2024-55 consistently showed minimal sporulation macroscopically and sparse mycelial development microscopically. Molecular validation with gene-specific SCAR markers revealed the presence of resistance genes viz. er1, er2, and Er3 in VP-2020-101, while VP- 2024-55 carried only er1. Marker ScOPE-161600 relaibly tracked er1, while ScOPX-171400 and ScW4637 confirmed the presence of er2 and Er3, respectively. Integrating phen-c and geno-typic data strongly supports VP-2020-101 as a promising donor genotype for pyramiding powdery mildew resistance in the popular garden pea cultivars/genotypes. These findings demonstrate the importance of integrated disease screening approaches to precisely identify robust sources of durable resistance facilitating their effective deployment in future pea breeding programs.