Exploring Resistance of Pea Pure Lines to Bacterial Leaf Blight (Pseudomonas Syringae Pv. Pisi): Insights for Breeding and Disease Management

Pea (Pisum sativum L.) is an important legume crop cultivated worldwide, and its productivity is significantly limited by bacterial blight caused by Pseudomonas syringae pv. pisi (Psp), a seed-borne pathogen responsible for severe yield losses. Despite its significance, resistant cultivars remain unavailable, necessitating systematic screening of pea germplasm to identify resistance sources for breeding. This study evaluated 22 pea lines (12 pure lines and 10 registered cultivars) under controlled greenhouse conditions for their response to Psp. The result showed that Melrose exhibited extreme susceptibility (score 5.0, 100% severity), while PS16002, PS16011, PS4(1), PS6(2), and Jofs were highly susceptible. Besides, correlation analysis revealed strong negative relationships between disease severity and grain yield (r = −0.82), pods per plant (r = −0.78), and seeds per plant (r = −0.80), while yield components were positively correlated (pods per plant × seeds per plant, r = 0.85). PCA distinctly separated the lines into three clusters: moderately tolerant (e.g., Utrillo, PS16011, PS16018), susceptible, and highly susceptible, accounting for 80.98% of the variance. The identification of moderately tolerant lines, such as Utrillo, PS16011, and PS16018, provides valuable sources of resistance for pea breeding.